the centre for materials science catalogue of ......shekhter, and göran wahnström emphasizes work...

CHALMERS UNIVERSITY OF TECHNOLOGY AND UNIVERSITY OF GÖTEBORG

THE CENTRE FOR MATERIALS SCIENCE

Catalogue ofResearch Projects

Publication No 1:1993

MC-

The Centre for Materials Science

Catalogueof Research ProjectsPublication No 1:1993

Göteborg, Sweden1993

Catalogue of Research ProjectsPublication No 1:1993ISSN 1104-3539ISRN CTH-MC-PBS -1 -SE

Editor: Associate professor Kent Skarp

Published by The Centre for Materials ScienceChalmers University of Technology and University of Göteborg

Address:The Centre for Materials ScienceChalmers University of TechnologyS-412 96 GöteborgSwedenPhone:+ 46 31 772 3384Fax:+ 46 31 77? 3584

Cover illustration: Eric WernerGraphic design: Information Office,Chalmers University of Technology

Printed by Svenskt TryckSuite 1993

Preface

Materials technology isof vital importance in every area of modern life. Basic

scientific research and technological applications go hand in hand and provide

mutual stimulation. Economical manufacturing technology, superior device

performance, minimized use of raw materials and energy, and diminished

environmental impact are key factors constantly providing new challenges for

materials research and development. The materials arena is of highly inter-

disciplinary character, and many of the most exciting developments lie at the

boundaries between traditional disciplines. This was realized at Chalmers

University of Technology and University of Gothenburg more than two

decades ago and led to the founding of a Centre for Materials Science. The

Centre serves as an umbrella for organizations involved in materials research

at the two Universities and at certain branch institutes in the Gothenburg

region. The general goal of the Centre is to promote materials research among

the member organizations as well as to provide a link to industry and to the

society at large.

Members of the Centre for Materials Science work on most aspects of

modern materials research, ranging from single-atom manipulation and

theoretical simulations to biomaterials and production engineering. In order

to give a presentation of the members and their research, the Centre produces

an inventory of materials research projects approximately every four years.

The 1993 issue is somewhat more extensive than previous editions, detailing

e.g. also scientific equipment and listing work published during the past four

years. The aim has been to keep a constant format for the 30 contributions.

However, since the Centre has among its members both academic groups and

external research institutes, with a different structure and scope than academic

groups, there are in some cases slight variations in the organization of the

material. As is evident from the list of contents, several members are active

in studies of many different classes of materials. The classification of

members presented thus gives only an indication of where their major

involvement within materials research is found.

This booklet, which has a wide distribution among industry, university

departments, and local research and governmental organizations, constitutes

the first issue of The Centre for Materials Science Publication Se. :es. It is

hoped that it will provide ample information on materials research in and

around Gothenburg. For more specific information on areas of particular

interest to you, please contact the coordinator or the individual researchers

named in the text.

Claes-Göran Granqvist Thomas Hjertberg Kent SkarpChairman (-1993) Chairman (1993-) Coordinator

The Centre for Materials ScienceOrganization and Members

ChairmanCoordinator

Secretary

Chalmers University of Technology and University of Göteborg

School of Physicsand Engineering PhysicsApplied Solid State PhysicsCondensed Matter TheoryElectronic Structure of Condensed MatterExperimental PhysicsInterdisciplinary MaterialsLiquid CrystalsIon and Semiconductor PhysicsMaterials and Surface PhysicsMaterials PhysicsMicroscopy and MicroanalysisMolecular PhysicsSemiconductor Physics and HeterostructuresSurface Physics

School of Mechanicaland Vehicular EngineeringEngineering MetalsPolymeric MaterialsProduction Engineering

School of Chemical EngineeringEngineering ChemistryInorganic ChemistryPolymer TechnologyPhysical Chemistry

School of Electricaland Computer EngineeringSolid State Electronics

School of Civil EngineeringBuilding materials

The Swedish Institute of Fibreand Polymer Technology- IFP-PGI- IFP-TEFO

IVF, The Swedish Instituteof Production Engineering F isearch

Swedish Ceramic Institute, SCI

Swedish National Testingand Research Institute, SP- Building technology- Chemical Analysis- Mechanics- Polymer Technology and

Surface Protection/Corrosion

IV

ContentsDepartments and members sorted according to main subject

General materials and surface scienceMaterials and Surface Physics 2Electronic Structure of Condensed Matter 13Thermal Transport Properties of Materials 22Interdisciplinary Materials 26Experimental Physics 32See also Surface Physics

Materials chemistryInorganic Chemistry 46Reaction Dynamics 58Chemical Analysis - Swedish National

Testing and Research Institute, SP 63

Polymers and fibresMaterials Physics 70Polymer Technology 78Polymeric Materials 87Polymer Technology and Surface

Protection/Corrosion - Swedish NationalTesting and Research Institute, SP 95

The Swedish Institute of Fibreand Polymer Technology, IFP-TEFO 102

The Swedish Institute of Fibreand Polymer Technology, IFP-PGI 106

BiomaterialsSurface Physics 114

Clusters and fine particlesMolecular Physics 126Engineering Chemistry 139

Electronic and optoelectronic materialsSolid State Electronics 148Semiconductor Physics and Heterostructures. 157Liquid Crystals 164

Superconductors and nanometerstructuresApplied Solid State Physics 174Condensed Matter Theory 196See also Materials PhysicsSee also Inorganic Chemistry

CeramicsSwedish Ceramic Institute, SCI 202See also Microscopy and Microanalysis

MetalsEngineering Metals 216Microscopy and Microanalysis 228Mechanics - Swedish National Testing

and Research Institute, SP 240

Building materialsBuilding materials 246Building technology - Swedish National


Production and materials processingProduction Engineering 262IVF, The Swedish Institute

of Production Engineering Research 264

Keywords 268

Alphabetical order, see next page.

ContentsIn alphabetical order

Applied Solid State Physics 174

Building materials 246Building technology - Swedish National


Chemical Analysis - Swedish NationalTesting and Research Institute, SP 63

Condensed Matter Theory 196

Electronic Structure of Condensed Matter 13Engineering Chemistry 139Engineering Metals 216Experimental Physics 32

Inorganic Chemistry 46Interdisciplinary Materials 26IVF, The Swedish Institute


Keywords 268

Liquid Crystals 164

Materials and Surface Physics 2

Materials Physics 70Mechanics - Swedish National Testing

and Research Institute, SP 240Microscopy and Microanalysis 228Molecular Physics 126

Polymer Technology 78Polymer Technology and Surface


Polymeric Materials 87Production Engineering 262

Reaction Dynamics 58

Semiconductor Physics and Heterostructures. 157Solid State Electronics 148Surface Physics 114Swedish Ceramic Institute, SCI 202

The Swedish Institute of Fibreand Polymer Technology, 1FP-PGI 106


Thermal Transport Properties of Materials 22

VI

General materialsand surface scienceMaterials and Surface Physics 2Electronic Structure of Condensed Matter 13Thermal Transport Properties of Materials 22Interdisciplinary Materials 26Experimental Physics 32

MATERIALS SCIENCE, 199.1

Materials and Surface Physics

Research Summary- Theory of condensed matter physics- Processes and phenomena at surfaces- Theory of materials

The materials- and surface-physics group aroundMats Jonson, Bengt Lundqvist, Mats Persson, RobertShekhter, and Göran Wahnström emphasizes workon fundamental surface physics, with an eye open tofor applications, theoretical and computational ma-terials physics, and mesoscopic physics.

The surface work is, in particular, focussed on thetheoretical description of the molecule-surface inter-action, encompassing all aspects on this interaction.As a prerequisite is a careful characterization of thesurface under study, and the interests also includeanalysis of experimental probes and spectra, andother surface phenomena. Complete descriptions ofadsorption, desorption, diffusion, crystal and thin-film growth, and surface reactions are aimed at. Theresults may find applications in heterogeneous ca-talysis, energy conversion, and intentionally struc-turing of materials.

The surface and materials studies share an inter-est in various potential-energy surfaces and thecorresponding electron structures, as well as indissipative processes for atomic and molecular mo-tion in extended media.

The computational physics uses Monte-Carlo,molecular-dynamics and electron-structure meth-ods.

Jonsons, Shekhter's and their collaborator's cur-rent interests are in the areas of nanometer structuresand mesoscopic systems. The novel nano-techniquehas created a new research field including a strongeffort at the submicron laboratory at CTH, and thereis a close experimental-theoretical collaboration,including joint seminars and projects. The activityon mesoscopic systems covers nanostructures, ultra-small tunnel junctions, and Coulomb blockade inone-electron tunneling.

AddressDepartment of Applied PhysicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 3199Fax+4631 77231 34

StaffSenior Membeis:Bengt LundqvistMats JonsonMats PerssonRobert ShekhterGöran WahnströmDavid Langreth

Research associates:Shiwu GaoBo Hellsing

Li ZhongwenDavorin LovricAlexander ZagoskinAndré Zwartkruis

Graduate StudentsYlva AnderssonJan-Olof BrånanderUrban EngbergChrister EngdahlTony FondenMagnus GisselfältAnna GrincwajgPeter HesslingTomas HolmquistThomas MattsonStella PapadiaJohan StrömqvistThomas SwahnBjörn von SydowUno Yxklinten

Secretary:Erica Värna

1

professor, tekn. dr.professor, tekn..dr.assoc. prof., docent, tekn.dr.assoc. prof., PhDassoc. prof., docent, tekn.dr.guest professor

»research associate, PhDresearch associate,docent,tekn.dr.post doc., PhDpost doc., PhDpost doc., PhDpost doc.,PhD

civ.ingfil.kand.civ.ing.tekn. lie.tekn. lie.civ.ing.civ.ingciv.ingciv.ingtekn. lie.tekn. lie.civ.ingciv.ingciv.ingtekn. lie.

THE CENTRE FOR

MATERIALS AND SURFACE PHYSICS

Major Instrumentation• Computer facilities: More than twenty modem

workstations.

Major Fields off ResearchA: Theoretical Surface and

Computational Materials Physicsparticipants: Bengt Ltindqvist, Mats Persson, GöranWahnström, David Langreth, Shiwu Gao, BoHellsing, Li Zhongwen, Davorin Lovric, AndréZwartkruis, Jan-Olof Brånander, Urban Engberg,Christer Engdahl, Tony Fondén.Thomas Mansson,Stella Papadia, Johan Strömqvist, Björn von Sydow,and Uno Yxklinten.

B: Mesoscopic Physicsparticipants: Mats Jonson, Robert Shekhter, Alexan-der Zagoskin, Magnus Gisselfält, Anna Grincwajg,Peter Hessling, and Thomas Swahn.

Research ProjectsA: Theoretical Surface and

Computational Materials PhysicsAl: Electrons at surfacesS. Yang, R.A. Bartynski, G. P. Kochanski, StellaPapadia, Tony Ponden and Mats Persson have dem-onstrated the existence of a surface resonance on asimple metal surface like Al(lll) in an energyregion far from any bulk band gap. In measuredscanning-tunneling spectra (STS) a peak is identi-fied. Theoretical modelling shows that it derivesfrom an electron resonance at the Al surface causedby scattering from the bulk lattice. The observedcorrelation between this peak in the STS and asimilarfeature in inelastic photoemission (IPE) spec-tra shows that the latter feature is also attributed tothis resonance, rather than a matrix element effect.

Shiwu Gao and Bengt Lundqvist have studied theconditions for having a sustained two-dimensionalelectron gas in surface Rydberg states. The surfacedensity and lifetime limited by the intra-band Augertransition are evaluated in a surface band modelcalculation.

For temperature effects in the electronic spectraof adsorbates Davorin Lovric has developed a modelfor calculating the substrate screening effects in the

electronic spectra of adsorbates. The model has beenapplied to CO weakly chemisorbed on Cu, where agood agreement with the experimental XPS spectrahas been found. The aim is to calculate the tempera-ture dependence of the XPS spectra of CO on Cu.

Lovric and Lundqvist have started a study ofnanometer-size metal clusters. Recent experimentshave revealed that the quantum electronic energystates of the nanometer-size metal (gold) clusterspersist upon the deposition of these clusters onto ametallic substrate (tungsten) and that tungsten sin-gle-atom tips exhibit a localized band structure of thetopmost tip atom. Work in progress deals withunderstanding of these features in the light of themodels developed for weakly bound adsorbates.References: publications 17,29,55-56,67.

A2: Vlxations at surfacesK. Burke, David Langreth, Persson and Z. Y. Zhanghave made a theoretical study of the vibrationalcontributions to the lineshape of a top bonded ad-sorbate. Dephasingof the adsorbate-substrate stretchmodes occurs via anharmonic coupling to lowerfrequency modes. Surprisingly, central forces, whichare often much larger than bond-bending forces, arefound not to contribute to the linewidth. This is dueto a cancellation between cubic and quartic terms inthe effective coupling to the dephasing modes. Thiscancellation is complete, whenever the probed modehas a frequency far above all others in the system, asfor, e.g., H/Si(lll) or the C O stretch in CO onmetals. For the C-metal stretch in CO on metals thecubic term introduces Fermi -resonance effects whichgreatly broaden the linewidth and also give rise toextra peaks in the absorption spectrum. However,the internal motion of the molecule causes a dramaticreduction in the magnitude of these effects. Onemust look to anharmonic terms in the non-central(bending) interatomic forces to explain the magni-tude of the experimental dephasing linewidth.

Using molecular dynamics with embedded-atompotentials, Y. Beaudet, L. Lewis and Persson haveinvestigated the role of anharmonicities at the (100)surface of Ni. In accord with recent LEED measure-ments, an anomalously large thermal expansion ofthe surface is observed, with a concomitant rapidincrease of the mean-square amplitudes of vibration,and an extraordinary attenuation of the LEEDintensities. These anomalies appear at a temperatureof about 900 K, well below the onset of disordering.

MATERIALS SCIENCE, 1993


There is no evidence of anomalous softening of thesurface phonons. The results suggest that the ob-served anharmonic behaviour results solely fromenhanced vibrational motion.References: publications 25-27.

A3: Primary surface processesAndré Zwartkruis and Fonden study Auger electrontransfer at simple metal surfaces by means of twodifferent models. In one model Auger rates andspectra are calculated using metal orbitals from aplanar ieilium surface, and in the other one metalcrbiials are calculated in a self-consistent potentialfor a simplified geometry. In the first-mentionedmodel results for the total neutralization rate for ahelium ion outside a surface have been calculated tolarge distances outside the surface. Energy spectrafor the resulting Auger electrons as well as for thecreated holes in the metal conduction band have beencomputed. The results show that the neutralizationprocess occurs qualitatively differently in two dis-tance regimes outside the surface. At a distance closeto the surface (up to about 10 bohr) electron-electroninteractions over long distances seem to be unimpor-tant. For larger ion-surface separations, long rangeinteractions become gradually more important. Ex-tensions of the model to other types of atomicorbitals including dynamical surface screening arein progress.

Gao has also studied hot electron scattering at aGaAs(l 10) surface, using a model calculation. Hefinds that the bulk-surface scattering is mediated bythe LO phonon emission in the hot electron gas.References: publications 50-52,75.

A4: Dynamics of molecule-surface interactionsFor atom-surface scattering on a rare-gas overlayeron a metal surface multi-phonon effects are particu-larly evident, due to the presence of low-energyEinstein modes. Charlotta Hedenäs and Perssonhave analyzed the sticking coefficient observed byStig Andersson, using both a simple forced-oscilla-tor model and a more elaborate single site multi-phonon approximation that is able to handle both thestrong corrugation and phonon inelasticity of theseoverlayers. The calculation suggests that the effectsfrom the strong surface corrugation for these layersdominate over the effects from the phonon inelastic-ity, in qualitative agreement with experimental ob-servations.

A puzzling observation by S. Andersson is theanomalous isotope dependence for sticking of H2and D2 molecules on Cu surfaces. In a multi-phonontheory for sticking Persson and Lovric arc piesentlyinvesrJgajng if this anomalous isotope effect ispresent already for the energy transfer to a singleoscillator.

ByD2 nozzle beamexperimentson coldCu(l 11),Cu(100) and Cu(110) surfaces S. Andersson andPersson have demonstrated that the substrate surfacestructure profoundly influences the sticking andtrapping of particles in the physisorption well.Comparision between theoretical calculations andmeasured data reveal that this is caused by structurespecific differences in the particle phonon couplingand the collision processes that control the lateralprogagation of particles trapped in quasibound states.Persson and S. Andersson are presently investigat-ing the crystal face anisotropy of the physisorptionwelldepthsforH2 and D2 interacting withthe(l 11),(100) and (110) surfaces of Cu. The effect seemsrelated to the work function differences.

Gao, Lundqvist and Persson have investigatedthe importance of electron-hole pairs in processes onmetal surfaces and proposed a mechanism for therecently developed atomic switch. This is an atomic-scale electronic device, whose operation is control-led by the displacement of an Xe atom between aNi( 110) surface and a W tip of a scanning-tunnelingmicroscope. The key ingredient is that the electronsparticipating in the current through the switch excitethe Xe atom vibrationaily in a double well, sustainedby the attraction to both surface and tip, and transferit to the other well. This theory accounts for theobserved facts and provides additional, easily test-able, predictions. For instance, Gao , Persson andLundqvist explain the power-law dependence of theXe transfer rate. The atomic switch thus gives anexperimental proof of the electron-hole pair mecha-nism for the energy transfer in dynamical processesat metal surfaces.

Carl Johan Setterlind has made a quantum-me-chanical calculation of electron-stimulated desorption(DIET) of positive ions. He finds that DIET de-scribed by the Menzel-Gomer-Redhead process isinfluenced by the attractive part of the potential.References: publications 20-21,24,28,68.

THE CENTRE FOR


A5: Surface reactions

Persson and Bret Jackson are extending their previ-ous modeling in an restricted geometry of an Eley-Rideal surface reaction for hydrogen, using time-dependent wavepacket calculations by keeping alldegrees of freedom of the molecule, but with a flatsurface potential. An important byproduct is thedevelopment of a technique for doing wave-packetpropagation in curvilinear coordinates. This task isperformed in close collaboration with theexperimentalist C. Rettner and B. Kay.

Bo Hellsing's research activity includes the stud-ies of the photochemistry of O2 chemisorbed onPt(l 11). He has investigated the direct mechanismfor photo-induced desorption and dissociation of t>>on Pt(l 11). Information about the local density-of-states is obtained from an embedded cluster calcula-tion. From an experimental point of view, differentaspects of the cross section has been studied, byvarying (i) photon frequency, (ii) polarization of thelight, and (iii) angle of incidence of the light. Incomparision with experiments it is shown (i) that the

Figure 1. The time evolution of the trajectories with acertain initial condition for an oxygen atom on anA l ( l l l ) surface. The figure shows the lateral positionsof the oxygen atom for all 64 trajectories at consecu-tive times with a time step of 9 fs. The projection onthe surface of the oxygen atom positions are markedwith crosses and the equilibrium surface atom posi-tions are marked with dots. The total time intervalrecorded is 0.45 ps and the length scale is given inÅngströms.

calculated cross sections are several orders ofmagnitudes too small, and (ii) that the polarizationexperiments show qualitatively different results incomparison with the calculations. It is concludedthat the substrate mediated mechanism must be ofimportance.

Hellsing collaborates with Vladimir P. Zhdanovon a project considering the substrate mediatedmechanism ("hotelectrons") forphoto-induced proc-esses at surfaces.

The possibility of "hot precursors" at surfaces, i.e.ballisticly moving hyperthermal adatoms, are im-portant for crystal growth and surface reactions.Recent STM data on dissociative adsorption of O2on Al( l l l ) has been interpreted in terms of hotprecursors. By performing stochastic trajectory cal-culations with realistic atom-surface potentials,Christer Engdahl and Göran Wahnström have deep-ened the analysis and found the "hot-precusor" con-cept to have limited applicability for the O atoms onthe Al surface.

Engdahl has also continued the stochastic-trajec-tory calculations of (i) dissociative adsorption of Hion Cu surfaces, further illustrating the importance oftaking all degrees of freedom into account, and (ii) ofthe surface-temper; ture and angular dependence ofthe sticking coefficient of N2 on Ag surfaces, in orderto reveal the orientational anisotropy of thephysisorption interaction.References: publications 14,22-23,48-49,58-59,77.

A6: Energetics of materials

Kenneth Holmluiid and Uno Yxklinten have appliedthe effective-medium theory to the lattice dynamicsof the high-Tc material YBaCuO, aiming at com-parisons with Raman-scatteringdata. Yxklinten stud-ies the energetics of various materials with theeffective-medium theory (EMT) and other methods.The studied systems include adsorbates interactingwith surfaces, e.g., H on Mg and Cl on K, metal-metal interfaces, and ceramic superconductors(YBaCuO,...). The so-called one-electron-energycorrection has been included in the EMT code, anduser friendly interfaces to the computer programshave been developed.

Recent studies of chemisorbed (metastable) oxy-gen on surfaces of noble and transition metalsdo notagree on the role of the d-electrons in molecular

MATERIALS SCIENCF., 1993


(2100)

CA B CC

Figure 2. (a) Potentiatenergy contours perpendicularto the surface (energy step 0.1 eV) for a single hydro-gen atom on a rigid Mg(0001) surface, (b) Potential-energy contours (energy step 0.1 eV) for a singlehydrogen atom in subsurface positions in a planeperpendicular to the Mg(000l) surface.

adsorption. Hellsing, P. Nordlander, and Zwartkruisplan to resolve these and other questions by using theCASTEP computer package in a thin-slab calcula-tion. As a first step Zwartkruis has visited a summe rschool entirely devoted to introducing this wellwritten package.

In order to calculate binding properties of sys-tems with strongly varying electron densities, e.g., inchemisorption, Zwartkruis is improving and mod-ernizing a Green's function code for cylindricalsymmetric problems. One of the objectives for this isto analyse the effective-medium theory by making adetailed comparison with self-consistent computa-tions.

interface and superlattice effects for layered me-tallic materials are being examined by Papadia intwo studies. In particular, it was proposed in theliterature in a simplified model (with unrealisticparameters) that Friedel oscillations would give riseto oscillations in interface excess energy with layerthickness. Papadia and Zwankruis have performedself-consistent jellium calculations in a sandwichgeometry with varying sandwich thickness and den-sity which reveal oscillating interface excess ener-gies of significant magnitude in these, more realistic,potentials. In a microscopic calculation employingthefull-potential linearmuffin-tin orbital (FP-LMTO)scheme, Papadia, K. Karlsson, P.O. Nilsson and T.Jarlborg has studied the change in elastic constantswith superlattice period for Mo/V layers. The trendsare compared to continuum-model predictions anddiscussed in the context of the so called supermoduluseffect in metallic superlattices.References: publications 46-47,66,69,96.

A7: Computational materials theory

During 1992 Thomas Mattsson has, together withWahnström, continued the work on quantum diffu-sion with application to hydrogen diffusion on anickel surface. The numerical method is based on theFeynman path-integral formulation. At low tem-peratures this path integral is dominated by the so-called instanton solution. This occurs, when there isa transition from an essentially classical diffusion toa quantum-mechanical one.

Wahnström has performed extensive molecular-dynamics calculations on the dynamics of a two-component atomic system. Two components areused to avoid crystal formation. The aim has been to

THE CENTRE FOR


test theoretical predictions and to make clear themicroscopic mechanism for relaxation processes onthe timescale of nanoseconds.

Together with L. Lewis, Montreal, Wahnströmhas studied a more complicated molecular systemaimed to describe o-terphenyl, one of the moststudied glasses. The molecule is treated as a solidbody, and the equations of motion arc solved byusinggeneralizedEuler angles, so-calledquatemions.Their model gives a surprisingly good agreementwith neutron-scattering data, and a secondary, slowrelaxation process is obtained. Studies of time-de-pendent quantities have revealed that this secondaryprocess derives from strongly anharmonic motionsof molecules that are trapped temporarily by thesurrounding molecules.

Wahnström and Yinggang Li have studied hy-drogen diffusion in Pd at temperatures significantlyabove room temperature, where a classical descrip-tion is expected to apply. To make clear the impor-tance of including the coupling to electronicexcitations molecular dynamics has been combinedwith stochastic simulation. Studies of hydrogen dif-fusion in Nb are now performed in collaborationwith Herbert Dosch, Miinchen.

Wahnström has been supervising diploma workson the corresponding questions for hydrogen in bulkmetal (Björn von Sydow), on solving the three-dimensional Schrödingerequation in an anharmonicpotential that has to be determined self-cons stently(Lennart Bengtsson), on hydrogen-induced recon-structions of a tungsten surface (Anders Nilsson andZhdanov), and on the sintering problem, i.e., on thegrowth of particleson surfaces (Per-Erik Skogholm).

Urban Engberg, in collaboration with Wahnströmand Yinggang Li, has used the Monte Carlosimulations of hydrogen diffusion in palladium toverify some basic assumptions of Transition StateTheory.References: publications 4-5,7-13,15,93-94.

A8: Interaction between large moleculesJan-Olov Brånander has studied optical properties ofphotosyntetic pigment system: "specially couplingand edge effects.References: publications 71-74.

B: Mesoscoplc Physics

B l : Uttrasrnall tunnel junctionsNew lithographic techniques and other technologi-cal progress have made possible the study of electrontunneling into ultrasmall conductors, into small clus-ters of atoms, and through very small Josephsonjunctions. The capacitance of these structures, beingproportional to the area of the tunnel junction, can bemade sufficiently small that the Coulomb energycorresponding to a single tunneling electron givesmeasurable effects. Wellknown charging effects inultrasmall tunnel junctions are the Coulomb block-ade and so called "single electron transistors". MatsJonson has recently studied the effect of the electro-magnetic environment on the Coulomb blockadeand charging effects injunctions driven by a micro-wave field. In the linear transport regime Jonson andRobert Shekhter have for some time been active.Results include Coulomb blockade effects in tunnelmicrotransport, the fundamental resistancequantization in point contacts and adiabaticmicrotransport in a magnetic field.

Magnus Gisselfalt is performing Monte-Carlosimulations of ultrasmall tunnel junctions coupled totransmission lines. A first aim is to study how theconductance of the junction is affected by the mag-nitude of the junction resistance and the impedanceof the electromagnetic environment A phase transi-tion from a Coulomb blockade-state to a conductingstate is expected. He is also studying parity-inducedsuppression of the Coulomb blockade of Josephsontunneling. Software development for the computertool Materialia is also an important activity of his.References: publications 37,39-40,78.

B2: Transport In constrained systems

Jonson and coworkers have studied the influence ofa magnetic field on the ballistic electron transportthrough single and multiple microconstrictions andthe eventual breakdown of quantized conductanceand the corresponding crossover to the mesoscopicregime as the length of a 10 channel is made longer.

Anna Grincwajg is working on problems relatedto the crossover from ballistic to diffusive transportin laterally constrained two-dimensional electronsystems.

Peter Hessling is inverstigaing the transport prop-erties of quantum contacts together with AlexanderZagoskin and Shekhter. The objectives are to derive



the quantum kinetic equation for the carriers insidethe contact and to apply it to the problem of itsresponse to external electro-magnetic field, finitebias, the phonon and impurity scattering etc.

Thomas Swahn studies ballistic transport in later-ally constrained low-dimensional systems. He hasbeen investigating non-ideal point contacts andboundary scattering effectsin high mobility AlGaAsstructures. Most recently he has been working onnarrow ballistic wires and non-equilibrium proper-ties of quantum dots. Recent results show fluctua-tions of the current on a new scale corresponding toa small fraction of the quantum unit of magnetic flux$ 0 = h/c.

Zagoskin has performed research in several ar-eas: The conductance of topologically nontrivial(doubly-connected) two-dimensional quantum con-tacts in the magnetic field of a thin solenoid has beendiscussed. It is shown that ther? are two typesof thesecontacts, planar and cylindrical ones, with qualita-tively different conductance dependence on themagnetic flux. In the second case the magnitude ofthe conductance oscil'.ations equals 2e2/h and isindependent of the details of the system's geometry.References: publications 30-33. 38, 82,87-88,95.

B3: Persistent current in a mesoscopic ringDror Lubin has studied the persistent current in anormal mesoscopic ring or cylinder, induced by atime-dependent Aharonov-Bohm magnetic flux. Thecharacteristic behaviour of the current is explainedas a manifestation of localization in energy space.References: publication 76.

B4: Heavy fermiortsThe non-linear temperature dependence of the Hallconstant in heavy-fermion compounds has beenexplained by Zagoskin on the basis of the self-consistent temperature shift of the chemical poten-tial, within the two-band hybridization model, with-out explicit reference to any magnetic (Kondo)interaction.

For certain heavy-fermion compounds Zagoskinhas analyzed the dependence of therresistivity on thepressure and magnetic field over a wide temperaturerange. The experimental data are well explained bya free-electron two-band- hybridization model, pro-vided that a self-consistent calculation of the chemi-cal potential is made.References: publications 89-92.

B5: Noise in hlgh-Tc superconductorsShekhter, Zagoskin, and G. Wendin have studiedoxygen diffusion and dynamical disorder in high-Tcsuperconductors, in particular low-frequency noisein superconducting tunnel junctions. They show thatthe noise is "diffusion-like" and proportional to thesquare of the contact current-vol tageratio. The noisemagnitude is sharply peaked near the maximal criti-cal temperature achievable for a given type of high-temperature superconductor by an optimal oxygendoping.

The screen-oriented computer program"NoiseScreen" is being constructed by Zagoskin tocalculate and plot the characteristics of the noise indifferent superconducting structures and to comparethem with the experimental data. The first part,describing low-frequency noise in a tunnel junctionmade of a high-temperature superconductor, basedon the predictions of the theory developed byShekhter, Zagoskin and G. Wendin, is in operation.The second part of "NoiseScreen" is being made toinclude Voss-Clarke theory of the low-frequencynoise superconductors.References: publication 81.

Publications

Ph.D. DissertationsGunnar Russbcrg, May 31,1989. Thesis: CATs, SETs and

Maps. Modelling and Dynamics of Selected NonlinearSystems.

Aarc Mällo, September 28,1990. Thesis: Modelling ofinteractions in metals.

Björn Rudbcrg, February 1,1991. Thesis: Electrontunneling in semiconductor structures - Scattering andpolarization effects.

Charlotta Hcdcnäs, May 10,1991. Thesis: Wavcpackctcalculations of scattering from surfaces.

Licentiate DissertationsBjörn Rudbcrg, May 31,1989. Thesis: Scattering Mecha-

nisms in Resonant Tunneling.

Charlotta Hcdcnäs, June 9 1989. Thesis: Panicle ScatteringAgainst Rigid and Vibrating Surfaces - QuantumMechanical Wavcpackct Propagation with Fast FourierTransforms.

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Uno Yxklinlen, November 30,1990. Thesis: Total-energycalculations with the effective-medium theory.

Stella Papadia, May 15,1991. Thesis: Electronic effects atmetallic surfaces and interfaces: image slate formationand charge redistribution.

Christer Engdahl, May 15,1991. Thesis: Studies ofdynamics of molecules on metal surfaces - trappingand dissociative adsorption.

Kenneth Holmlund, March 24,1992. Thesis: High Tem-perature Superconductors - Structure and LatticeDynamics of YBa2Cu3O7.

Carl Johan Setterlind, June 9,1992. Thesis: DesorptionInduced by Electronic Transitions - A Study withQuantum Mechanical Wavepackct Propagation.

Jan-Olov Brånander, June 10,1992. Thesis: Absorptionand Adsorption Aspects in Photosynthesis andBiocompatibility.

Thomas Mattsson, March 19,1993. Thesis: Transition statetheory from path-integrals, applications to hydrogendiffusion on Ni{100)

Diploma WorkBjörn von Sydow, November, 1992. Thesis: Numerical

calculations for hydrogen in metals using quantum-mechanical methods.

Reports and articles1. "Rate Equations, Rate Constants and Surface Diffu-

sion", G. Wahnstrom, in Interaction of Atoms andMolecules with Solid Surfaces, Eds. V. Bortolani,N.H. March, and M.P. Tosi, (Plenum, New York,1990).

2. "Hydrogen motion on a rigid Cu surface: The calcula-tion of the site to site hopping rate by using flux-fluxcorrelation functions", K. Haug, G. Wahnstrom, and H.Mctiu.J.Chcm.Phys. 92,2083(1990).

3. "Hydrogen Diffusion on Metal Surfaces - NonadiabaticEffects", G. Wahnstrom, in Many-Atom Interactions inSolids , eds. R.M. Nicmincn, M.J. Puska, and M.J.Mannincn (Springer-Vcrlag, Berlin, 1990).

4. "Dynamic anomalies in a supercooled liquid: Amolecular dynamics study", G. Wahnstrom, PhysicaScripta 44,166,1991.

5. "Dynamic susceptibility in a supercooled liquid: Amolecular dynamics study", G. Wahnslröm, J. Non-Crystalline Solids , 131-133,109,1991.

6. "Dynamics and statistics of surface diffusion at finitecoverages", G. Wahnstrom, and V.P. Zhdanov, Surf.Sci. 247,74,1991.

7. "A molecular dynamics study of a supercooled two-component Lcnnard-Jones system", G. Wahnstrom,Phys. Rev. A 44,3752,1991.

8. "Nonadiabauc effects in hydrogen diffusion in metals",Y. Li, and G. Wahnstrom, Phys. Rev. Lett. 68,3444,1992.

9. "Relaxation of molecular glass at intermediate times",L J. Lewis, and G. Wahnstrom, Institute Report 92-25.

10. "Molecular dynamics simulation of hydrogen diffusionin palladium", Y. Li, and G. Wahnstrom, Phys. Rev. B, in press.

11. "H motion in Pd and Nb: a molecular-dynamics study",Y. Li, and G. Wahnstrom, in Materials Theory andModeling, eds. P. Bristowc, J. Broughton, and J. M.Ncwsam, in press.

12. "Numerical calculations for hydrogen in metals usingquantum mechanical methods", B. von Sydow,Applied Physics Report 92-12.

13. "Some tests of basic assumptions in transition statetheory for hydrogen diffusion in metals", U. Engbcrg,Y. Li, and G. Wahnstrom, J. Phys.: Condens. Matter,to be submitted.

14. "The question about transient mobility in dissociativechemisorption of O2 on Al(l 11)", C. Engdahl, and G.Wahnstrom, Surf. Sci., to be submitted.

15. "Diffusion of hydrogen in palladium and niobium", G.Wahnstrom, and Y. Li, invited review to Mod. Phys.Lett. B , in preparation.

16. "Mean Free Path of Trapped Physisorbcd HydrogenMolecule", M. Persson, L. Wilzén.and S. Andersson,Phys, Rev. B 41,5331,1990.

17. "Electron Rcsonaccs on Free-electron like Metals", S.Papadia, M. Persson, and L.-A. Salmi, Phys. Rev. B41,10237,1990.

18. "Vibrational Lineshapcs at Surfaces", D. Langrcth, andM. Persson, Phys. Rev. B 43,1353,1991.

19. "Anisotropy of the Physisorption Interaction betweenH2 and Metal Surfaces", S. Andersson, L. Wilzén, andM. Persson, Phys. Rev B 43,7003,1991.

20. "Possible electronic mechanism behind nanotribologyof rare-gas monolaycr", M. Persson, Solid StateCommun. 80,917, 1991.

21. "Inelastic scattering and sticking of hydrogen mol-ecules at adsorbed rare gas overlaycrs", CM. Hcdcnäs,and M. Persson, Phys. Rev B 45,11273, 1992.



22. "A quantum mechanical study of recombinativedesorption of atomic hydrogen on a metal surface", B.Jackson, and M. Persson, J. Chem. Phys. 96,2378,1992.

23. "Vibrational excitation in recombinative desorption ofhydrogen on metal surfaces: Eley-Rideal mechanism",B. Jackson, and M. Persson, Surf. Sci. 269/270,195,1992.

24. "Atomic Switch proves importance of electron-holepare in processes on metal surfaces?", S. Gao, M.Persson, and B.I. Lundqvist, Solid State Commun. 84,271.1992.

25. "Vibrational dephasing at surfaces: the role of cubicanharmonicity and Fermi resonances", K. Burke, D.Langketh, M. Persson, and Z.Y. Zhang, Phys. Rev. B ,submitted (1992).

26. "Anharmonic effects at the Ni(100) surface", Y.Beaitfet, L. Lewis, and M. Persson, Phys. Rev. B,accepted (1992).

27. "Anharmonic effects at the (100) and (110) surfaces ofNi", Y. Beaudet, L. Lewis, and M. Persson, in Materi-als Theory and Modeling,, eds. P Brisiowc, J.Broughton, and J. M. Newsam, in press.

28. "Sticking in the physisorplion well: Influence ofsurface structure", S. Andersson, and M. Persson, Phys.Rev. Lett., accepted (1992).

29. "Surface barrier resonances on a simple metal", S.Yang, R.A. Bartynski, G. Kochanski, S. Papadia, T.Fonden, and M. Persson, Phys. Rev. Lett. 70,849(1993).

30. "Field-induced adiabalic transport in 2D ballisticsystems", L.I. Glazman, and M. Jonson, Phys. Rev.Lett. 64,1186,1990.

31. "Globally adiabatic regime in quantum ballistictransport", L.I. Glazman, and M. Jonson, Phys. Rev. B41,10686,1990.

32. "Quantum fluctuations and the single-junction Cou-lomb blockade", S.M. Girvin, L.I. Glazman, M.Jonson, D.R. Penn, and M.D. Stiles,Phys. Rev Lett.64,3183,1990.

33. "Tunneling times in quantum mechanical tunneling",M. Jonson, in Quantum Transport in Semiconductors,eds. D. Ferry, and C. Jacoboni, Plenum Press, NewYork, (1990).

34. "Electron-phonon contribution to the thcrmopowcr ofmetals", M. Jonson, G.D. Mahan, Phys. Rev. B 42,9350,1990.

35. "Interface roughness and asymmetry current-vottagccharacteristics in resonant tunneling", B.G.R. Rudbcrg,Semicond. Sci. Technol. 5,600,1990.

36. "Optical phonons in resonant tunneling", B.G.R.Rudberg, Semicond. Sci. Technol. 5,328,1990.

37. "Quantum fluctuations and charging effects in smalltunnel junctions", K. Flensberg. and M. Jonson, Phys.Rev. B 43,7586,1991.

38. "Breakdown of conductance quantization andmesoscopic fluctuations in the quasi-ballistic regime",L.I. Glazman, and M. Jonson, Phys. Rev B 44,3810,1991.

39. "Tunneling in a self-consistent dynamic image poten-tial", B.G.R. Rudberg, and M. Jonson, Inst. Rep. 90-36.

40. "Dynamic image potential and traversal time for atunneling electron", B.G.R. Rudbcrg, and M. Jonson,Phys. Rev B 43,9358,1991.

41. "Towards a spin polarized effective medium theory",U. Engbcrg, Inst. Rep. 90-58, (Diploma work).

42. "Quantum mechanical wavepackct calculation ofinelastic scattering of neon against Cu(100)", CM.Hedenäs, Inst. Rep. 9049.

43. "Electron tunneling through a double barrier withelectron-phonon interaction in the mean field approxi-mation - wavepacket simulation", CM. Hedenäs, andB.G.R. Rudberg, Inst. Rep. 90-50.

44. "Theoretical aspects of adsorption", B.I. Lundqvist, inPhysics of solids and liquids: Interactions of atoms andmolecules with solid surfaces, eds. V. Bortolani, N.H.March, and M.P. Tosi, Plenum Press (1990), pp.213-254.

45. "Direct determination of transformation coefficients inGram-Schmidt, orthonormalization", Z.J. Tian, Inst.Rep. 90-57.

46. "Hydrogen-Magnesium Interaction Energies", U.Yxklinten, Z.J. Tian, A. Mällo, C Engdahl, and B.I.Lundqvistjnst. Rep. 90-33.

47. "Total-Energy Calculations with the Effective-MediumTheory", U. Yxklintcn, Licentiate thesis, 1990.

48. "Hydrogen dissociation on copper: importance ofdimensionality in calculations of the sticking coeffi-cient", C. Engdahl, and U. Nielsen, J. Chcm. Phys., inprint.

10 THE CENTRE FOR


49. "Multidimensional effects in dissociativechemisorption: H2 on Cu and Ni surfaces", C. Engdahl,B.I. Lundqvist, U. Nielsen, and J.K. Norskov, Phys.Rev. B , in press.

50. "Computation of the Auger rate for a He+ ion ap-proaching a simple metal surface", T. Fonden, and A.Zwartkruis,Surf. Sci. 269/270,601,1992.

51. "Auger rates and spectra for simple models of He+ infront of a metal surface", A. Zwartkruis, and T.Fonden, Surf. Sci., submitted.

52. "Analysis of Auger spectra from a Hc+-ion in front of asimple metal surface", T. Fonden, and A. Zwartkruis,Applied Physics Report 92-14.

53. "Coulomb blockade in single tum.el-juncuons: quan-tum mechanical effects of the electromagnetic environ-ment", K. Flcnsberg, S.M. Girvin, M. Jonson, M.D.Stiles, and D.R. Penn, Z. Phys. B 85,395,1991.

54. "Quantum mechanics of the electromagnetic environ-ment in the single-junction Coulomb blockade", K.Flensberg, S.M. Girvin, M. Jonson, D.R. Penn, andM.D. Stiles, Physica Scripla T42,189,1992.

55. "Auger decay of Surface Rydberg State", S. Gao, andB.I. Lundqvist, Prog. Theor. Phys. Suppl., 106,405,1991.

56. "Two-dimensional Fermi Liquid in Surface RydbergStale; Limits set by Auger Decay", S. Gao, and B.I.Lundqvist, Solid State Commun. 84,147,1992.

57. "Wavepacket Calculations of Scattering from Sur-faces", CM. Hedenäs, PhD thesis, 1991.

58. "Molecular Oxygen on Metals", B. Hellsing, and S.Gao, Chem. Phys. Lett. 187,137-142,1991.

59. "Chemisorbed molecular oxygen on metals; interactionand charge transfer", B. Hellsing, and S. Gao, Inst.Rep. 91-45.

60. "Effect of intra-atomic Coulomb repulsion on chargetransfer in atom-metal surface scattering", B. Hcllsing,and V.P. Zhdanov, Surf. Sci., submitted (1992).

61. "Kondenserad materias fysik - oväntade upptäckteroch nya vägar", M. Jonson, B.I. Lundqvist, and S.Lundqvist, Kosmos 1991, p. 109.

62. "Aspects of Molecule-Surface Interactions", B.I.Lundqvist, Surf. Sci. 242,365,1991.

63. "Calculation of the Force-Dipole Tensor for Hydrogenin Palladium and Platinum", A. Mällo, and U.Yxklinten,Z.Phys.B 83,213-216,1991.

64. ""Up-hill" Diffusion and Hydrogen-Hydrogen Interac-tion in Palladium-Platinum Alloys . A. Mällo, and A.Krozer, J. Less Common Metals 167,305-317,1991.

65. "FEM Calculation of the Elastic H-H InteractionEnergy for Hydrogen in Metals", A. Mällo, 168, J.Less Common Mcials 168,361-375,1991.

66. "Electronic structure of metallic supcrlattices: Mo/V",S. Papadia, K. Karlsson, P.O. N .son, and T. Jarlborg,Phys. Rev. B , 45,1857 (1992).

67. "Electronic effects at metallic surfaces and interfaces:image state formation and charge redistribution", S.Papadia, Licentiate thesis, 1991.

68. "Desorpuon induced by electronic transitions studiedwith a timcdcpcndcnt quantum mechanical method",CJ. Scttcrlind, Surf. Sci. 269/270,175-179,1992.

69. "Calculated chemisorption properties of Magnesium ,Z.J. Tian, U. Yxklinten, B.I. Lundqvist, and K.W.Jacobsen, Surf. Sci. 258,427-438,1991.

70. "Studies of dynamics of molecules on metal surfaces -trapping, and dissociative adsorption", C. Engdahl,Licentiate thesis, 1991.

71. "Optical absorption in pigment aggregates", J.-O.Brånander, P. Apell, and T. Gillbro, J. Biophysics,(1993), accepted.

72. "Adsorption of Brownian particles on a solid-liquidinterface", J.-O. Brånander, last. Rep. 92-26.

73. "Optical absorption of one- and two-dimensionalpigment aggregates", J. Hartford, and J.-O. Frånandcr,in preparation.

74. "Absorption and Adsorption Aspects in Photosynthesisand Biocompatibilily", J.-O. Brånanccr, Licentiatethesis, 1992.

75. "Inelastic Hot Electron Scattering at GaAs(l 10)surface", S. Gao, Solid State Commun., in print.

76. "Persistent currents as an indication of localization inenergy space", D. Lubin, ITP 92-10.

77. "The direct mechanism for photoinduccd desorptionand dissociation of O2 on Pl(l 11)", B. Hcllsing, Surf.Sci. 282,216,1993.

78. "Parity-induced Suppression of the Coulomb Blockadeof Josephson Tunneling", K.A. Matveev, L.I. Glazman,M. Jonson, and R. Shekhtcr, Applied Physics Report92-5.

MATERIALS SCIENCE, 1993 11


79. "Point-contact spectroscopy of the elcctrcn-phononinteraction near metal surface and a planar defect",Yu.A. Kolesnichcnko, and R.I. Shckhter, Proc. Int.Conf. on Point-Contact Spectroscopy (PCS "91), Fiz.Nizk. Temp. ,18,478,1992.

80. "Nonlinear effects in the case of transverse electronfocusing in metals", Yu.A. Kolcsnichenko, and R.I.Shckhtcr, Proc. Int Conf. on Point-ContactSpectroscopy (PCS '91), Fiz. Nizk. Temp., 18,520,1992.

81. "Oxygen diffusion and dynamical disorder in high-Tcsuperconductors: low frequency noise in superconduct-ing tunnel junctions", R.I. Shekhtcr, A.M. Zagoskin,and G.Wendin, To appear in: Proc. World Congresson Superconductivity, Munich, 1992.

82. "Nonlinear electrical conductivity of ballistic quantumcontacts", A.M. Zagoskin, JETPLett., 52,436,1990.

83. "On the possibility of the direct observation of thedifference between cyclic and zero boundary condi-tions", A.M. Zagoskin, and I.O. Kulik, J. Phys. Cond.Matt. 2,5271,1990.

84. "Transport of local pairs in metallic oxides: calculationof frequency and temperature dependence of conduc-tivity", R.I. Shckhtcr, G. Wcndin, and I.O. Kulik, Phys.Rev. B 44,10215,1991.

85. "Optical spectroscopy of localized states in metallicoxides", R.I. Shekhtcr, Z. Crljcn, and G. Wcndin,Physica Scripta, submitted (1992).

86. "Single-electron tunneling into randomly distributeddouble-electron states: linear voltage and temperaturedependence of the conductance of high-Tc tunneljunction", M. Hurd, R.I. Shckhtcr, and G. Wendin,Phys. Rev. B , submitted (1992).

87. "Quantum interference in double-connected ballisticcontacts", A.M. Zagoskin, Proc. Int. Conf. on Point-Contact Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18,637,1992.

88. "1/f noise and clectron-phonon interaction in pointcontacts", A.M. Zagoskin, I.O. Kulik, and A.N.Omelyanchouk, Proc. Int. Conf. on Point-ContactSpectroscopy (PCS '91), Fiz. Nizk. Temp., 18,665,1992.

89. "A non-Kondo maximum in electric resistivity of someheavy-fermion compounds and its dependence onpressure and magnetic fields", A.S. Rozhavsky, I.G.Tuluzov, and A.M. Zagoskin, Proc. Int. Conf. on Point-Contact Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18,529,1992.

90. "On the temperature dependence of the Hall constant insome heavy-fermion compounds: a qualitative theory",A.M. Zagoskin, and A.S. Rozhavsky, J. Phys. Cond.Matt. 4,7115,1992.

91. "Influence of pressure and magnetic field on thetemperature-dependent resistivity of hcavy-fcrmionsystems", A.S. Rozhavsky, A.M. Zagoskin, Yu.G.Naidyuk, and I.G. Tuluzov, Phys. Rev. B , submitted(1992).

92. "Magnetic field dependence of cyclotron masses inheavy fcrmion conductors in a two-band hybridizationmodel", A.S. Rozhavsky, A.A. Zvyagin, and A.M.Zagoskin, Physica B, submitted (1992).

93. "H diffusion on Ni (100), a quantum Monte Carlosimulation", T.R. Mattson, Applied Physics Report 93-8.

94. "Transition state theory from path-integrals, applicationto hydrogen diffusion on Ni (100)", T. Mattson,Licentiate thesis, 1993.

95. "Magnetic flux-induced conductance steps inmicrowires", E.N. Bogacheck, M. Jonson, R.I.Shckhtcr, and T. Swahn, Applied Physics Report 92-9.

96. "High Temperature Superconductors - Structure andLattice Dynamics of YBa2Cu3C>7", Kenneth Holmlund,licentiate thesis, 1992.

12 THE CENTRE FOR

Electronic Structureof Condensed Matter

Research SummaryPhotoemission, inverse photoemission and othertechniques are used to study the electronic structureof solid materials, including their surfaces and in-terfaces. The main tool is angle-resolved photoelec-tron spectroscopy in the UV range, ARUPS. De-tailed information is obtained with this method aboutvalence states in the volume, surface states andresonances, chemical shifts of core levels and more.Some surfaces are prepared by cleaving, while oth-ers are obtained by epitaxial evaporation. For thelatter purpose an MBE-system has been connectedto a surface physics analytical chamber. RHEED andLEED can be applied. The whole complex is at-tached to the storage ring for synchrotron light at theMAX-facility in Lund. We should also mention thatduring the period a complete scanning Auger systemhas been installed, enabling us to do mapping anddepth profiling on e.g. the MBE samples.

A central theme in the research activity concernssurfaces and interfaces of semiconducting systems.By means of dispersion of valence states and corelevel shifts detailed geometric and electronic infor-mation is obtained. Examples of interest are surfacereconstructions, surface states and band offsets forelemental, III-V and II-VI compounds. Anotherexample is the effect on the band structure of inter-calation in layered materials.

The experimental research is supported by com-putational physics. Recently a method for calcula-tion of partial, local density of states for realisticsemiconductor surfaces was developed.

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31 7723312Fax+46 31 165176

StaffSenior MembersLars liverJanusz KanskiPer-Olof NilssonHans Starnberg

Graduate StudentsHans BrauerYousefKhazmiÖrjan Olsson

SecretaryAnn-Marie Frykestig

civ.ing.docentprofessordocent

fil.kand.M.Sc.civ.ing.

Major Instrumentation• Angle-Resolved Photoelectron Spectroscopy.

The photoelectron spectroscopy facilities includefour units. One is an ADES 400 (Vacuum Gen-erators) system, where the radiation is generatedby either a discharge lamp (21 -41 e V) or an X-raytube (1256 and 1487 eV). A spherical sectoranalyser is movable in the horizontal plane. Thesystem is further equipped with a band passphoton detector and electron gun for inversephotoemission, LEED, sputtering ion gun, sam-ple manipulator with heating, sample introduc-tion chamber and gas inlet system. Another sys-tem (in-house design) is equipped in much thesame way, except that the X-ray source is re-placed with a cylindrical mirror energy analyserfor Auger spectroscopy. A third system is con-nected to a McPherson monochromator (7-11eV) and equipped with facilities for epitaxialgrowth of binary alloys. The fourth system forangle-resolved studies is used at MAX-lab inLund (beamline 41). It is equipped with LEEDand an MBE system (see below).

• Scanning Auger MicroprobeA UHV scanning Auger microscope (PHI model590) is used for secondary electron or Auger


ELECTRONIC STRUCTURE OF CONDENSED MATTER

electron imaging, as well a« point analysis. Anargon sputter gun is available for depth profilemeasurements. The instrument is operated with aprimary electron energy up to 10 KeV and has aspatial resolution of = 0.3 pm in the lateralimaging. A sample handling system enable fastloading of specimens into the instrument, butgives no options for sample treatment except ionbombardment.

Molecular Beam EpitaxyAt the storage ring for synchrotron light at MAX-lab, Lund an MBE-system and sample transfersystem has been connected to the photoemissionchamber at beamline 41. The liquid nitrogencooled system contains 5 effusion cells withcomputer controlled shutters and RHEED. Aspecial UHV system has been constructed forsample analysis (e.g. Auger Spectroscopy) andused when the MBE system is not on-line theMAX-ring.

High Resolution X-ray Diffraction.The Philips HRD instrument is a five crystaldiffractometer intended for characterisation ofsemiconductor crystals. Ka-radian'on from a 2000W Cu tube is collimated by a four crystal mono-chromator before reaching the sample. Using theGe(440) reflection of the monochromator theangular divergence in the beam is 0.0015°. Thesample is mounted in a computer controlled threeaxis goniometer, with option for x-y translation.A slit collimated detector is scanned togetherwith the goniometer to obtain rocking curveswith extremely high angular resolution. Informa-tion is obtained about lattice constant, compo-sition and lattice strain in heteroepitaxialoverlayers

Major Fields of ResearchA: Electronic structure of Semiconductor

SurfacesParticipants: L. liver, J. Kanski, Y. Khazmi, P.O.Nilsson, and Ö. OlssonCollaborators: C. Håkansson, Lund University andU.O. Karlsson, KTH, Stockholm

B: Electronic structure of Interfaces andOverlayers on Semiconductors

Participants: L. liver, J. Kanski, Y. Khazmi, and P.O.NilssonCollaborators: C. Håkansson, Lund University, U.O.Karlsson, KTH, Stockholm, G. LeLay, CRMC2-CRNS, Marseille, France, S.P. Svensson, MariettaLaboratories, Baltimore, USA,

C: Layered Materials and intercalationParticipants: H. E. Brauer and H. StambergCollaborators: L. J. Holleboom, Lund University,H.P. Hughes, University of Cambridge, U.K.,

D: Catalytic Oxidation of SemiconductorSurfaces

Participants: H. StambergCollaborators: K. M. Choudhary, University of Notre-Dame, USA, Z. Hurych, Northern Illinois Univer-sity, USA, P. Soukiassian, CEA, Saclay, France

E: Implantation DamagedSemiconductors

Participant: J. KanskiCollaborators: G. Petö, Central Research Institutefo: Physics, Budapest, Hungary

F: Studies of UnoccupiedElectronic States

Participants: L. liver, J. Kanski, P.O. Nilsson, and H.StambergCollaborators: V. N. Strocov, International Instituteof Interface Interactions

G: Many-body Effects in Solid StateSpectroscopies

Participants: P.O. Nilsson and H. StarnbergCollaborators: H.P. Hughes, University of Cam-bridge, U.K. and S.P. Svensson, Marietta Laborato-ries, Baltimore, USA

H: Computational Physics - ElectronicStructure of Materials

Participants: K. Karlsson, Y. Khazmi, and P.O.NilssonCollaborators: O. Gunnarsson and O. Jepsen, Max-Planck-Institute, Stuttgart, Germany, R.J. Needs, A.Qteish, and R.W. Godby, Cambridge, U.K., E.Sobczak, Institute of Physics, Warsaw, and T.Jarlborg, University of Geneva

14 THE CENTRE FOR


Research Projects

A: Electronic structureof Semiconductor Surfaces

Our work within this project has been focused on twosubjects: investigations of surface core level shiftsand mapping of bulk and surface valence states.

Core level photoemission has become a veryuseful technique for surface characterisation due toits ability to give direct information about the num-ber of inequivalent surface sites and thereby provideuseful test of current models of the surface geometry.We have employed this method to studies of com-pound as well as elemental semiconductors. As anexample we have investigated the reversible phasetransitions on the Ge(100) surface, reflected bydifferent reconstructions in electron diffraction. Ourresults show that the 2x1 surface reconstruction isconnected with formation of asymmetric surfacedimers, and that this local dimer configuration is alsopresent at the bw temperature c(4x2) as well as thehigh temperature lxl phases.

Studies of surface and bulk valence band stateshas largely been motivated by the need of reliablereference data for current and future investigationsof heterojunctions and superlattices. The work hastherefore been concentrated on the [ 100] surfaces ofdifferent semiconductors, e.g. Ge, InP, InAs andAlAs.References: 26,42,57,58

B: Electronic structure of Interfacesand Overlayers on Semiconductors

Bl: Metal-Semiconductor InterfacesCore level photoemission has been widely appliedfor studies of metal-semiconductor junctions duringthe last decade and much of the present knowledgeabout the microscopic development of Schottkybarriers is based on such data. We have pointed outthat this approach may introduce errors to the esti-mated barrier heights of ~ 0.1 - 0.2 eV, due tosignificant changes in the non-local electrostaticscreening. To test these ideas we have performedexperiments, in which the metal-semiconductor junc-tion is made on a layered semiconductor system. Byvarying the thickness of a spaces layer, we havefound that effects of non-local screening are indeed

hv (eV) 20

Figure 1(a). The band structure of CdTe derived fromphotoemission measurements at normal emissionfor a range of photon energies hv. An empiricalLCAO band structure has been fitted to the experi-mental data.

(b). Surface states and resonances deduced fromthe angular dependence of photoemission data.The surface projected LCAO band structure isshown as a shadowed region.For more details consult references 2 and 28.

of the predicted magnitude. This means thatphotoemission derived Schottky barrier heights onn-type semiconductors are systematically overesti-mated by - 0.1 eV, while barriers on p-type semi-conductors are correspondingly underestimated.

An independent test of the dielectric screeningmodel has been made by applying it to photoemissionfrom noble gas adsorbates on semiconductors and onmetals. Good agreement has been found betweenexperimentally observed and model predicted corelevel shifts, giving further support to the conclusionson Schottky barriers.References: 27,35,38,47,48.



3MLInAs:InP(100)As(3d)

8 = 6 0 °hv=105eV

' ' ' ' I ' ' ' ' IAs:InP<100)As(3d)

22 23 24

Kinetic energy (eV)

Figure 2The As 3d core level in InAs overlayers as obser-ved in photoemission. The lower panel refers toan lnP(110) substrate covered with one monolayerof InAs. Two inequivalent As surface positions areobserved demonstrating the formation of asym-metric dimers. The upper panel shows the samefor three monolayers InAs. Here an As signal from"the bulk" is also observed. Further informationcan be found in reference 34.

B2: HeterojunctlonsDue to the inherently limited probing depth in photo-electron spectroscopy it is in principle not possible touse this method for studies of an interface betweentwo semi-infinite media. Still, since the interfaceelectron structure is believed to be established forvery thin overlayers, photoemission has become avery common tool. To test the validity cf this as-sumption we have undertaken systematic studies ofthedevelopment of the three-dimensional band struc-ture with increasing semiconductor overlayer thick-ness. From studies of InAs overlayers on InP wehave concluded that even for 3 monolayers thickfilm the overlayer does not exhibit bulk characteris-tics.

In an attempt to get around the mentioned inher-ent limitations we have performed photoemissionexperiments on a GaAs/Al As superlattice grown ona stepped GaAs substrate. As an effect of the steppedstructure and fractional layer MBE deposition, thegrowth results in a so called tilted superlattice, withthe interfaces between the component materialsreaching the physical surface. Assuming that theinterface pinningmechanismsissignificantlystrongerthan surface state induced band bending, this confi-guration should be well suited for studies of interfacecharacteristics, e.g. the valence band offset. Fromour experiments an offset of 0.4 eV was deducedbetween the valence band maxima of AlAs andGaAs.References: 34,39

C: Layered Materials and Intercalation

The collaboration with Dr. H. P. Hughes, Universityof Cambridge, UK has continued. Ti 3d electronicstates of TiS2, induced by intercalated excess Ti, hasbeen studied by angle-resolved phptoemissionspectroscopy. The character of such states could beconclusively established by evaluation of their dif-ferent behaviour as the temperature was changed.An extensive study of the layered material VSe2,including thermal effects, led to the successful sepa-ration of direct transitions from the indirect spectralcomponent. By applying inverse photoemissionspectroscopy (IPES), together with secondary elec-tron emission spectroscopy (SEES) and total currentspectroscopy (TCS), we also obtained detailed in-formation about the unoccupied bands of VSe2, andstudied the enhancement of the secondary electronyield induced by surface adsorbates. At MAX-labthe intercalation of VSe2 by Cs was studied usingsynchrotron radiation. A drastic transition from three-dimensional to two-dimensional behaviour was ob-served, and this is presently being analysed andcompared to band calculation^ by Dr. L. J. Hilleboomat the University of Lund.References: 36,40,41,53,56

16 THE CENTRE FOR


D: Catalytic Oxidationof Semiconductor Surfaces

The studies of alkali-metal promoted oxidation ofsemiconductor surfaces, in collaboration with North-em Dlinois University, USA has continued. Thelinearrelationship between oxide thickness and loga-rithmic oxygen exposure was found to be a generalfeature of alkali-metal covered surfaces of elemen-tary semiconductors, while a different behaviourwas observed for III-V semiconductors. The cata-lytic nitridation of III-V semiconductors was alsodemonstrated, and the bonding of alkali metals at theInP( 110} surface was studied by photoemission ex-tended x-ray absorption fine-structure (PEX AFS) ina collaboration with Dr. K. M. Choudhary, Univer-sity of Nctre-Dame, USA.References: 4-11,21-24,52,54,55

plement to inverse photoemission spectroscopy(IPES) and is highly sensitive to structures normallynot seen in IPES. By using a method developed byDr. V. N. Strocov, International Institute of InterfaceInteractions, St. Petersburg, Russia it is possible todetermine the band structure without the uncertaintyabout perpendicular wavevectors inherent in mostother techniques. In an initial study of VSe2 the TCSmethod was compared to IPES and secondary elec-tron emission spectroscopy (SEES). The Cu(100)surface has been extensively studied, and these dataare being analysed.

The theoretical and experimental projects utilis-ing IPES have continued. Cd(OOOi) was studiedboth experimentally and theoretically and interbandtransitions, density of state effects and excitations ofsurface states and resonances were identified.References: 16,17,36,4,50

E: Implantation DamagedSemiconductors

The earlier reported anomalous amorphous state ofimplantation damaged Ge has been subject to con-tinued investigations. Gear similarities were foundbetween electron diffraction patterns from transmis-sion electron microscopy on the implanted Ge withX-ray diffraction patterns on liquid Ge, supportingthe idea that the implantation damaged material issignificantly more disordered that obtained by eva-poration. The question of possible contaminationstabilisation of the amorphous state has been ad-dressed via self-implantation in UHV conditions. Itwas then found that the photoemission spectra ofsuch samples were essentially identical to thoseobtained on Sb implanted ones.References: 18,19

F: Studies of Unoccupied States

A project involving studies of unoccupied bands ofmetals and semiconductors - using Total CurrentSpectroscopy (TCS) - has been initiated. Thesestudies can provide information which is crucial tothe correct interpretation of photoemission data, andoffers possibilities to test theoretical models of theelectronic structure of solids. The method is a com-

6: Many-body Effectsin Solid State Spectroscopies

6 1 : Temperature Dependence in PhotoemissionWe have performed systematic investigations ofthermal effects as seen in photoemission spectra,using UV-light. These effects, which may be crucialin the interpretation of photoemission spectra, in-clude changes in positions, widths and heights ofspectral peaks, as well as appearance of new spectralfeatures. Of these the height changes usually domi-nate, but they show irregular variations, which areinconsistent with conventional Debye-Waller theory.A more recent theory suggests that valence-bandspectra are a complicated mixture of direct andindirect contributions, of which the former are redu-ced by Debye-Waller factors, while the latter in-crease in intensity as the temperature is raised, andfurthermore are strongly angle-dependent due to k-space weighting. Our measurements on Cu andVSe2 surfaces essentially confirm this. In addition tothis we have developed a procedure by which directand indirect contributions successfully can be sepa-rated. Our main conclusions so far are:

- It is possible to enhance direct and indirect con-tributions by making linear combinations ofEDC's measured at different temperatures.



- The indirect contributions are already at roomtemperaturecomparable in size to the direct ones,and they are characterised by strong angulardependence. In general the indirect componentsare quite similar to the direct ones, but signifi-cantly broader than typical direct transitions.

- The success of the decomposition procedureindicates that the temperature dependencies ofthe direct and indirect components, respectively,are fairly uniform.

We have also exploited thermal effects in photo-emission in studies of impurity states in "self-inter-calated" titanium disuJphide, Ti 1+XS2.References: 3,40,53,56

62: Vale Auger Spectra fn nteonductcThe L.WVV Auger spectrum of InP(l 10) has beeninvestigated using synchrotron radiation as the exci-tation source. All observed features could be iden-tified using a one-body theory involving convolu-tions of partial, local density of states functionsobtained from a band calculation and atomic transi-tion probabilities. A quantitatively good agreementwith experiment was obtained using an effectiveCoulomb repulsion Ucff = 0.8 eV, which simulatesthe hole-hole interactions in the valence band. Fur-ther investigations (also considering surface effects)should show whether our results are typical for III-V and II-VI semiconductor compounds.Reference: 33

H: Computational Physics -Electronic Structure of Materials

Artificial structures, such as semiconductor hetero-junctions and short-period superlattices, have beenwith investigated with respect to the band offset attheir interfaces. A method for tuning the offset wasproposed, whereby (n,m) was varied for the inter-face GaAs/(AlAs)n(GaAs)m . The metallicsuperlattice Mo/V was studied with emphasis onhydrogen storage.

The effect of final state screening on the Schottkybarrier height, as deduced from core level shifts, wasinvestigated by model calculations using dielectricfunctions e(q). It was found that such effects could beoftheorderofO.leV.

Chemical shifts in copper oxides with differentformal valences were calculated. The results couldbe used to get insight into the electronic structure ofthe high Tc-material YBa2Cu306_5.

The one-step model for inverse photoemissionwas further developed to include the possibility ofimage state excitation by secondary beams.

Photoemission spectra of Cd(OOOl) have beencalculated using a multiple scattering theory, whichamong other thongs identifies surface states andresonances.

A computer program has been developed tocalculate the partial and local surface electronicstructure of realistic semiconductorsurfaces, includ-ing reconstructions and overlayers.References: 20,43-46,49,50.

PublicationsPh.D. DissertationsH. Qu, "Studies of the Electronic Structure of Some Clean a-dAs-covcrcd Semiconductor Surfaces using Angle-ResolvedSpectroscopy", 1991

K. Karlsson, "Electronic Structure Calculations: Materialswith Weak and Strong Correlations", 1992

Diploma WorkF. Prässlcrand U. Heydcnrcich, "Electron Energy Loss FineStructure", 1992

Ö. Olsson, "Anglc-rcsolvcd Photoclcctron Spectroscopy ofInSb(100)", 1992

H. Braucr, "Fermi Surface Studies with Angle-ResolvedUltraviolet Photoclcctron Spcctoscopy"

Reports and articles1. J.F. Morar, U.O. Karlsson, R.I.G. Uhrbcrg, J.Kanski,

P.O. Nilsson, and H. Qu, Angle-resolved photocmissionstudy of the As/Gc(100) interface Journal of AppliedSurface Sciencc,41/42 (1989) 312

2. H. Qu, P.O. Nilsson, J. Kanski and L. Ilvcr, The Elec-tronic structure of CdTc(llO) as studied by anglc-rc-solvcd photocmissionJ'hys.Rcv. B39,5276 (1989)

3. P.O. Nilsson, L. Ilvcr, H.I. Stamberg, and D. S.-L. Law,Anomalous Temperature Dependence in Pholocmissionfrom Cu(l 11), JPhys.: Condcns. Matter 1,6159 (1989)

4. K M Choudhary, P S Mangat, H1 Stamberg, Z Hurych,DKildayandPSoukiassian, Low-coverage alkali-mctal-induccd surface structural changes in III-V semiconduc-tors: Pholocmission extended x-ray absorption finc-struc-lurc study of the Na/InP(l 10) interface, Phys. Rev. B 39,759 (1989)

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5. ZDHurych, HI Stamberg and PSoukiassian, Photon-stimulated desorpiion (PSD) study of H+ ions from cleanand oxygen-covered Cs/Si(100)2xl surfaces, Europhys.Lett. 8. 567(1989)

6. KMChoudhary,PSMangai,DKilday,GMargaritondo,P Soukiassian, HI Stamberg and Z Hurych, Low-cover-age metal-induced structural changes in the substrate atmetal/InP(i 10) interfaces determined by phoioemissionextended. X-ray absorption fine structure, J. Vac. Sci.Technol.A7,2024(1989)

7. HIStarnberg,PSoukiassianandZHurych,Alkali-meta!-promoted oxidation of the Si(100)2xl surface: coveragedependence and nonlocalityJPhys. Rev. B 39, 1277S(1989)

8. PSoukiassian, HI Stamberg and T Kcndclcwicz, Insula-tor-semiconductor interface formation by electronic pro-motion using alkali metal and removal of the catalyst,Appl. Surf. Sci. 41/42,395 (1989)

9. P Soukiassian and H I Stamberg, Alkali metals andsemiconductor surfaces: Electronic, structural and cata-lytic properties in Alkali adsorption on metals and semi-conductors .Ed.H.P. Bon/.cl, A. M. BradshawandG. Ertl(Elsevier 1989).

10. HI Starnberg, P Soukiassian, M H Bakshi and Z Hurych,New aspects in the oxidation kinetics of alkali-metalpromoted group IV and III-V semi-conductor surfaces.Surf. Sci. 224,13 (1989)

11. PSoukiassian and HI Stamberg, Chemisorption of alkalimetals on semiconductor surfaces, Vuoto 19,151 (1989)

12. H.Qu,J.Kanski,P.O.Nilsson,andU.Karlsson,Valencebands and surface states of CdTc( 110), J. Elcctr. SpectrRelated Phenomena 51,149 (1990)

13. J. Kanski, H. Qu, P.O. Nilsson, and U. Karlsson,PhcHoemission studies of the GaAs(100)-4xl surface, J.Electr. Spectr. Related Phenomena 52,133 (1990)

14. H. Qu, J. Kanski, P.O. Nilsson, V.O. Karlsson, and J.F.Morar, Angle-resolved phoiocmission from CdTc(MO)andCdo.65Mno.35Tc(110),PhysicaScripta,41,164(1990).

15. H. Qu, J. Kanski, P.O. Nilsson and U.O. Karlsson, Va-lence bands and surface state of CdTc(llO): A newsurface resonance in the GX azimuth, Vacuum 41,610(1990)

16. H.S.Chauhan,L.Ilvcr, P.O. Nilsson, J. Kanski and U.O.Karlsson, The electronic structure of Cd(0001) as studiedby phoiocmission, inverse phoiocmission and computa-tions, Vacuum 41,531 (1990)

17. P.O. Nilsson, Direct and Inverse Phoioemission fromMetals and Semiconductor Surfaces, Proc. Int. School onSurface Physics. Beijing 20-30 March, 1990, Editors: D-S Wang and D-H Shen. World Scientific, Singapore,1990

18. G. Peiö, G. Kotai and J. Kanski, Surface regrowth ofimplantation damaged Ge(l 11), Vacuum 41,618 (1990)

19. G. Peiö, L. Rosta, J. Kanski, A. Ban», E. Menelle and R.Balissent, Indication ofan anomalous amorphous state ofGe induced by heavy ion implantation, J. Non-crysl Sol.125,258(1990)

20. K. Karlsson, RJ. Needs, A. Qtcish and R.W. Godby,Tailoring materials for quantum wells: band offsets at(001)-oricntcdGaAs/(AlAs)n(GaAs)minterfaccs,J.Phys.:Condensed Matter 2,5265 (1990)

21. Z D Hurych, P Soukiassian and HI Stamberg, "Photonstimulateddcsorption(PSD)of positive ions from cesiatedsemiconductor surfaces using synchrotron radiation",Phys.Scr. 41 (1990)935.

22. P Soukiassian, T Kcndelewicz, H I Siamberg, M HBakshi and Z Hurych, Catalytic nitridation of a III-Vsemiconductor using alkali metal, Europhys. Lett. 12,87(1990)

23. HIStambcrgandPSoukiassian,"Alkali metalpromotedoxidalionof semiconductors: Oxidation kinetics",Vacuum41(1990)678.

24. P Soukiassian, H I Stamberg, T Kendelewicz and ZHurych.Room-tcmperatureniLidau'onof gallium arsenideusing alkali metal and molecular nitrogen, Phys. Rev. B42(1990)3769.

25. J.Kanski,P.ONilsson,U.O.Karlsson,andS.P.Svensson,Electron Structure Studies of the InP(100):As Surface,Proc. of 20th Int. Conf. on the Physics of Semiconductors,World Scientific 1990, Editors: E. M. Anastassakis andJ.D. Joannopoulos

26. J. Kanski, P.O. Nilsson, U.O. Karlsson.andS.P. Svensson,Band mapping of MBE-grown AlAs(100), Solid StateCommun. 77,617 (1991)

27. K. Karlsson, O.Nyqvist and J. Kanski, Final-state effectsin phoiocmission from metal-semiconductor interfaces,Phys. Rev. Lett. 67,236 (1991)

28. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson,Anglc-rcsolvcd pholocmission studies of the CdTe( 110)surface, Phys. Rev. B43,14 589 (1991).

29. Surface band structure of ZnTc(llO) studied byphoiocmission, H. Qu, J. K2->ski, P.O. Nilsson, and U.O.Karlsson, Surface Science 251/252,233 (1991)



30. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson,Angle-resolved photoclcctron spectroscopy study of thesurface electronic structure of ZnTc(l 10), Phys. Rev.B43,9843 (1991)

31. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson, Bulkand surface electronic structure of ZnSe(l 10), Phys. Rev.B44,1762(1991)

32. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson,Surface electronic structure of InP(llO) studied withangle-resolved photoelectron spectroscopy. Surface Sci-ence 225,237 (1991)

33. P.O. Nilsson and S.P. Svensson, The Phosphorus AugerL2.3V V Spectrum of InP( 110), Solid State Commun. 79,191(1991)

34. J.Kanski,P.O.Nilsson,U.O.Karlsson,andS.P.Svensson,Photoemission study of a thin epitaxial InAs layer onInP(001), Applied Surface Science 56-58,604 (1992)

35. G. Le Lay, J. Kanski, P.O. Nilsson, and U.O. Karlsson,Core-level spectroscopy study of the initial formation oftin-germanium interfaces, Applied Surface Science 56-58,178 (1992)

36. H.I. Starnberg, P.O. Nilsson, and H.P. Hughes, Conduc-tion band structure of VSc2 studied by inversephotocmission, secondary emission and total current, J.Phys.: Condens. Matter 4,4075 (1992)

37. Y. Khazmi, J. Kanski, P.O. Nilsson, Z. Lin, M.C.Håkansson,and U.O. Karlsson, Identification of surfacestates at the CdTc(l 10) surface by means of Cs adsorp-tion, Surface Science 269/270,844 (1992)

38. J. Kanski, K. Karlsson, P.O. Nilsson, S.P. Svensson,M.C.Häkansson, and U.O. Karlsson, MetaJ-scmiconduc-lor interfaces: Final-State Effects in Photo-emission, Pro-ceedings from the21st International Conference on Phys-ics of Semiconductors, Beijing, 1992

39. Y.Khazmi,L.Ilver,J.Kanski,P.O.Nilsson,U.O.Karlsson,and S. P. Svensson, Photocmission studies of tilted GaAs/AIAs superlattices, Proceedings from the 6th Interna-tional Conference on Supcrlatlices, Microstructurcs andMicrodevices, Xian. 1992

40. H.I. Stamberg and P.O. Nilsson, Thermal effects in angle-resolved photoemission: is it possible to separate directand indirect transitions? Surface Science 1992

41. H.I.Slamberg,P.O.Nilsson.andH.P.Hughes, Adsorbatcinduced enhancement of secondary electron emissionfrom the layered compound VSc2 Surface Science 1992

42. G. Le Lay, V. Yu. Aristov, J. Kanski, P.O. Nilsson, U.OKarlsson, K. Hricovini, and J.E. Bonnet, Electronic prop-erties of cleaved (110) and MBE-grown (100) InAssurfaces, clean and covered with an ultra-thin Ag ad-layer, Hague conf. -92

43. K. Karlsson, O. Gunnarsson and O. Jepsen, Shape of theCu 2p core level photocmission spectrum for monova-lent, divalent and trivalcnt Cu compounds, J. Phys.:Condens. Matter 4,2801 (1992)

44. K. Karlsson, O. Gunnarsson and O. Jepsen, Chemicalshifts for monovalent, divalent and trivalcnt Cu com-pounds, LPhys.: Condensed Matter 4,895 (1992)

45. O. Gunnarsson, K. Karlsson and O. Jepsen, Chemicalshifts and core level line shapes for monovalent, divalentand trivalcnt Cu compounds, Particles and Held series 49;Synchrotron Radiation and Dynamic Phenomena, editedby A. Bcswick (AIP new York, 1992) p. 550

46. K. Karlsson, O. Gunnarsson, and O. Jepsen, Cu 2pchemical shifts for YBa2Cu3Oö.5: Valence of the Cuatoms, Phys. Rev. B45,7559 (1992)

47. J. Kanski, K. Karlsson, O. Nyqvist, P.O. Nilsson, U.O.Karlsson, M.C. Håkansson, and S.P. Svensson, Final-stateeffects in photocmission from metal-semiconductorintcrfaces.Proceedings from the Tenth International Con-ference on Vacuum Ultraviolet Radiation Physics (VUV10), Paris (1992)

48. K. Karlsson, O. Nyqvist, and J. Kanski, Differences infinal state effects for adsorbatcs on metal and semicon-ductor surfaces, J. Vac. Sci. Technol. B10,1335 (1992)

49. S. Papadia, K. Karlsson, P.O. Nilsson, and T. Jarlborg,Electronic Struc tureof metallic supcrlatu'ces:Mo/V,Phys.Rev. B45,1857(1992)

50. P.O. Nilsson, K. Karlsson, and J. Rundgren, Prediction ofimage state excitation by secondary beams in inversephotocmission spectroscopy, Phys.Rcv B15 (1992)

51. L. liver and P.O. Nilsson, Angle-Resolved UVPhotocmission from Single Crystals of AgPd Alloys,Acta Physica Polonica A 82,723 (1992)

52. P Soukiassian, T Kcndclcwicz, H I Stamberg and ZHurych, Rb- and K-promotcd nitridalion of cleaved GaAsand InP surfaces at room temperature, Appl. Surf. Sci. 56-58,772(1992)

53. HIStambcrg.PONilssonandHPHughcs.Photocmissionstudy of the Ti 3d electron pockets in self-intercalatedTiS2, Mat. Sci. Forum 91-93,727 (1992)

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54. HI Starnberg, P Soukiassian and T Kcndclewicz, GaP,GaAs, and InP nitridation at room temperature by N2

adsorption on (110) surfaces modified by alkali metals,Surf. Sci. 269/270,915 (1992)

55. HI Stamberg, P Soukiassian, S T Kim, A Papageorgo-poulos and S Kapoor, Logarithmic exposure dependencein alkali-metal promotedoxidation of elemental semicon-ductors. Surf. Sci. 269/270,934 (1992)

56. H I Stamberg, L liver, P O Nilsson and H P Hughes,Thermal effects in photoemission from VSc2: Separationof direct and indirect contributions, Phys. Rev. B (1992)

57. G. LeLay,J. Kanski, P.O. Nilsson, U.O. Karlsson, and K.Hricovini, Surface core level shifts on Gc( 100): c(4x2) to2x1 and lxl phase transitions, Phys. Rev. B45, 6692(1992)

58. S.Wiklund,U.O. Karlsson,J.Kanski.andH.Qu,Surfaceshifts of the Se 3d and the Te 4d core levels of ZnSe( 110)and ZnTe(l 10), Phys. Rev. B, 1992

59. M.C. Håkansson.U.O.Karlsson,J.Kanski.P.O.Nilsson,Y. Khazmi, and K. Hricovini, Dimer formation andelectronic structure on the Ge(IOO) (2xl):Sb surface,Surface Science Letters 278, L2131 (1992)

60. E.Sobczak,P.O.Nilsson,andK.Karlsson,Photoemissionof Cd(0001) using Synchrotron Radiation, Acta PhysicaPolonicaA82,337(1992)

61. P.O. Nilsson, Photoelectron Spectroscopy by Synchro-tron Radiation, Acta Physica Polonica A 82,201 (1992)

62. P.O. Nilsson, Ultraviolet Photoelectron and InversePhotoemission Spectroscopy, Proceedings 2nd Interna-tional Seminar on X-ray and Electron Spectroscopy,Madralin, Poland, Sept. 4-7,1989, p. 48 Printed by PolishAcademy of Sciences 1990. Editors: J. Auleytner andK.Lawniczak-Jablonska.


Thermal Transport Propertiesof Materials

Research SummaryThe transport properties that are being studied by theresearch group include Thermal Conductivity, Ther-mal Diffusivity and Electrical Resistivity. Frominformation about the thermal properties it is alsopossible toestimate the Specific Heat of the material.

A wide range of materials have been studiedmany at the requests from outside research anddevelopment laboratories. However, recently ourinterest has been focused on High Tc materials andparticularly the behaviour of the Thermal Conduc-tivity at and around the transition temperature.

As a complement to the previously developedtransient methods (Transient Hot Strip and PulseTransient Hot Strip) the TPS-(Transient PlaneSource)- method has been introduced. It is presentlybeing used for Thermal Conductivity and ThermalDiffusivity measurements from cryogenic tempera-tures up to about 1000 K. It is a convenient tool forroutine measurements, which makes it possible forus also to perform measurements at requests fromoutside research laboratories. The reason for con-tacting our group for assistance with measurementsis because there are hardly any laboratories in thecountry where measurements can be routinely per-formed over a Thermal Conductivity range from0.02W/mKtolOOW/mK.

Recently studies with the Pulse Transient HotStrip (PTHS) method were initiated. The mi:—,strips used in this technique make it possible to studyinsulating layers of thicknesses down to and belowone micrometer. The reason for the growing interestin thin layers is that certain classes of materials areonly used in or can only be produced in the form ofthin layers. Earlier measurements made in our re-search group indicate that the thermal properties ofinsulating layers produced for instance by vacuumevaporation have thermal properties that are quitedifferent from those of the corresponding bulk ma-terial.

AddressDepartment of PhysicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 3176Fax +46 31 3177

StaffSenior MembersSilas GustafssonEmest Karawacki

docentdocent

Graduate StudentsBashir Suleiman M.Sc.Tomas Hultgren fil.kand.

Technical StaffKerstin Gustafsson Ing.

Major Instrumentation• Low Temperature Cryostat (Oxford Instruments)• Evaporation Unit (Edward's 306)• TPS-Measuring Units• Specially designed furnace for Thermal Con-

ductivity measurements up to 1000 K.• (One of the TPS-Measuring Units and the

furnace are frequently used for measurementsof thermal conductivity of new materials at therequests of outside R & D laboratories)

Major Reids of Research

A: Thermal Conductivity (Bulk material)Participants: Silas Gustafsson, Ernest Karawacki,Bashir Suleiman, Tomas Hultgren and KerstinGustafsson

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Collaborators: Asghari Maqsood (Associate Profes-sor) and Izhar-ul-Haq (Graduate Student) Depart-ment of Physics, Quaid-i-Azam University Islama-bad, Pakistan, N S Saxena (Associate Professor)Department of Physics University of Rajasthan,Jaipur, India.

B: Transient Methods for MeasuringThermal Conductivity

Participants: Silas Gustafsson, Ernest Karawacki,Bashir Suleiman and Kerstin Gustafsson

C. Thermal Conductivityof Micrometer Layers

Participants: Silas Gustafsson and Ernest Karawacki

Research Projects

A: Thermal Conductivity (Bulk material)

A l : Thermal Conductivity of Hlgh-Tc MaterialsOne Yttrium- and one Erbium-based 1,2,3 High Tcmaterial have been studied within a temperaturerange around the transition temperature. Both ther-mal conductivity and electrical resistivity have beenmeasured.

Studies of these materials have been performedearlier but only with steady state methods. Thereason for taking up these studies was the possibilityto work with much smaller temperature differencesthan in the steady state methods and then see if themeasured properties would be influenced by thetemperature differences that appear in the sampleduring the different measuring procedures.

The results from the two different methods ofmeasuring the thermal properties agree well. How-ever, there is one rather striking difference. Frommeasurements with steady state methods there arereports on a an increase of the Thermal Conductivityjust below the transition temperature of about ten percent. However, with the Transient Plane Sourcemethod we have reported increases between 50 and100 per cent, which means that we see a verydramatic increase in the transport properties justbelow Tc. This high thermal conductivity falls offrather quickly as the temperature is further loweredbecause of boundary scattering or the Casimir effect.

THERMAL TRANSPORT PROPERTIES OF MATERIALS

A2: Thermal Conductivity of CompositesOver the last ten years we have had a rather closecollaboration with the research groups at the PhysicsDepartments in Islamabad, Pakistan and Jaipur,India, with the support from International ScienceProgram in Uppsala. As part of this collaboration agraduate student Izhar-ul-Haq has recently spenttwo years in our research group as part of a Ph Dsandwich program. In addition longer and shorterexchange visits have been arranged.

The measurements on composites in our grouphas been in support of studies performed for manyyears at these other laboratories. The specific interestin these systems is due to the interest in arrangingmaterials with low Thermal Conductivity particu-larly if the material if kept in panels at reducedpressure.

B: Transient Methods for MeasuringThermal Conductivity

B l : Transient Plane Source MethodIn a paper from 1979 we outlined the Transient HotStrip method; and in 1984 we published the firstpaper on the Pulse Transient Hot Strip method,which in contrast to the THS-method was designedfor the study of insulating micrometer thick layers.

In continuation of this work the Transient PlaneSource (TPS) method was developed and publishedin 1991. This method uses plane TPS-elementsplaced between the flat surfaces of two pieces of thesample material under investigation. The transient

"Hot dish".



recording of a TPS-experiment is limited in time sothat there is no influence on the temperature increaseof the TPS-element from the outside boundaries ofthe sample pieces. With such an experimental proce-dure it is obvious that the shape of the outsideboundaries have no effect on the measurement.

This method uses a thin metal foil (incorporatedin the TPS-element) both as heat source and tem-perature sensor in the same way as in the THS-method. However, the conducting pattern is not inthe form of a straight strip but can be given a ratherarbitrary shape. The pattern design of the conductingmaterial in the TPS-element used by us is mainly thatof a double spiral, which effectively reduces the heatflow inside the sensor during a transient recording.The sensors are, for room temperature and cryogenicwork, made of a 0.01 mm thick metal foil sand-wiched between two sheets (thickness 0.025 mm) ofKapton. The sensors for temperatures above 500 Kare insulated by sheets of a mica material. Thesensors are produced in collaboration with CalescoFoil AB.

Since the TPS-elements are electrically insulatedit is possible to make measurements on both insula-tors and electrically conducting materials.

The experimental techniques described aboveare presently used at twelve different research labo-ratories throughout the world.

B2: Dynamic Plane Source MethodsThe TPS-elements described above have also beenused as plane heat sources and temperature sensorsin the recently published Dynamic Plane SourceMethod, which in contrast to the TPS-method uses aone dimensional heat flow.

These methods are very convenient whenever theheat losses from the sample boundaries can beneglected. By using different parts of the voltageversus time recordings it is possible to estimateConductivity, Diffusivity and Specific Heat inde-pendently.

B3: Studies of Building MaterialsIn collaboration with groups at "Statens Prov-ningsanstalt" studiesofbuildingmaterialshavebeeninitiated. Since a TPS-element can be placed at adistance from the recording instrumentation (Volt-meter, Power Supply, Bridge and PC) used for theexperiments, the TPS-method can in principle beused for field experiments. It would for instance be

possible to place sensors anywhere inside a building,building construction or insulating material withelectrical leads attached and then connected to acentrally located measuring panel and from thereperform measurements and follow variations in theThermal Conductivities at the various locations ofthe sensors. Because of limited resources this kind ofexperiment has so far not been possible to arrange.

B4: Round Robin Measurementsand Requests from R & D Laboratories.

The research group has participated in two RoundRobin measurements. One series of measurementswas initiated by Cabannes (France) and Minges(USA) and involved the study of Cecorite 130P, acordierite-based ceramic material provided byLafarge Company, France, and used for a COD ATAmeasurement program. The results of these meas-urements have been summarised in a paper pre-sented at arecent Thermal Conductivity conference.

The other study involved measurements onCorning 9606, a Pyroceram material. This study hasnot been summarised yet.

At the requests of both Swedish and foreign R &D laboratories measurements of Thermal Conduc-tivity have been performed over temperature rangesup to about 1000 K on a large number of differentmaterials.

C. Thermal Conductivityof Micrometer Layers

Cl: Development of the Pulse TransientHot Strip Method

In 1987 Aslam Chohan was awarded his Ph D degreefrom our group and the subject of his thesis was thePulse Transient Hot Strip method. This method usesevaporated micro-strips for studies of layers withthicknesses down to and below one micrometer. Theapproximate dimensions of a typical micro-strip are:Length 0.5 mm, Width 0.01 mm and Thickness 50nm.

Thermal Conductivity measurements have beenperformed on fused quartz and compared withvacuum evaporated Silicon Dioxide. Studies havealso been made on Gallium Arsenide and LiquidCrystals.

Measurements with this method is just beinginitiated after a recent development of the experi-mental procedure, which will result in a significant

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simplification of the theory, which in the generalcase is rather complex. 1:. J measurements will alsoinclude a renewed study of Liquid Crystals at therequest by the Liquid Crystal group at the PhysicsDepartment.

The micro-strips will be produced with assistancefrom the Nano-Meter Facility within the PhysicsDepartment. This very important facility will makeit possible to produce micro-strips with a precision,which will greatly improve the reliability of theThermal Conductivity measurements.

Publications

Diploma WorkTomas Hullgren: "Konstruktion av instrument för bestäm-ning av värmekonduktivitet hos fasta anisotropa material.(Fall semester 1991).

Reports and artides"Temperature Dependence of Thermal Conductivities andThermal Diffusivities of Composites using Transient Hot-Strip Method", N S Saxena, S E Gustafsson, M A Chohanand A Maqsood. Int. Journal of Energy Research 13 (1989)411.

"Anordning för mätning av tcrmiska egenskaper hos enprovsubstai.s", Silas E Gustafsson, Swedish Patent No 461177. American Patent No 5 044 767, Japanese and PCTApplication No PCT-SE89-OO137.

"Transient Plane Source Techniques for Thermal Conducti-vity and Thermal Diflusivity Measurements of Solid Mate-rials". Silas E Gustafsson. Rev Sci Instrum 62 (1991) 797.

"Simultaneous Measurement of Thermal Conductivity andThermal Diffusivity of Rock - Marbles Using TransientPlane Source (TPS) Technique", Izhar-ul-Haq, N S Saxena,S E Gustafsson and A Maqsood, Heat Recovery Systems &CHP11 (1991)249.

"Thermal Transport in Building Materials", Silas EGustafsson and Ernest Karawacki, Swedish Council forBuilding Research. Document D11:1991.

"Thermal Conductivity and its Temperature Dependence inSelected Steel Samples", N S Saxena, S E Gustafsson andIzhar-ul-Haq, (manuscript).

"Dynamic Plane Source Technique for SimultaneousDetermination of Specific Heat, Thermal Conductivity andThermal Diffusivity of Metallic Samples", E Karawackiand B M Suleiman, Meas Sci Technol 2 (1991) 744.

"Dynamic Plane-Source Technique for Study of theThermal Transport Properties of Solids", E Karawacki andB M Suleiman, High Temp - High Pres 23 (1991) 215.

"An Extension to the Dynamic Plane Source Technique forMeasuring Thermal Conductivity, Thermal Diffusivity, andSpecific Heat of Dielectric Solids", E Karawacki, B MSuleiman, I ul-Haq, and Bui-Thi-Nhi, Rev Sci Instrum 63(1992)43901.

"Thermal Conductivity of the Ceramic Cecorite 130Pbetween 88 and 280 K Measured Using the Transient PlaneSource Technique", Bashir M Suleiman, Izhar-ul-Haq,Ernest Karawacki and Silas E Gustafsson, J Phys D: ApplPhys25(1992)813.

"Thermal Conductivity and Electrical Resistivity of the Y-and Er-substituted 1-2-3 Superconducting Compounds inthe Vicinity of the Transition Temperature", B M Suleiman,I Ul-Haq, E Karawacki, A Maqsood and S E Gustafsson.(Submitted for publication).

"The Transient Plane Source Technique: ExperimentalDesign Criteria". Silas E Gustafsson, Bashir Suleiman,Narendra S Saxena and Izhar-ul-Haq, High Temperature-High Pressure 23 (1991) 289.

"Recent Work with and Developments of the PTHS-(PulseTransient Hot Strip) Technique", Silas E Gustafsson andErnest Karawacki, (manuscript).

"Simultaneous Measurements of Thermal Conductivity andThermal Diffusivity of Insulators, Fluids and ConductorsUsing Transient Plane Source (TPS) Technique", AMaqsood, N Amin, M Maqsood, G Shabbir, A Mahmoodand Silas E Gustafsson, Int J Energy Research (in press).

"Thermal Conductivity and Diffusivity of KH2PO4 andNH4H2PO4 Polycrystallin Samples in the Neighbourhoodof their Transition Temperatures", B M Suleiman, (manu-script).

"Thermal Conductivity and Thermal Diffusivity of aCordierite-Based Ceramic. Results of a COD ATA mea-surement program", F Cabannes and M L Minges, HighTemp - High Press 21 (1989) 69.

Communication at the Conference on Phonon Scattering,Silas E Gustafsson, Cornell University, August 1992.


Interdisciplinary Materials

Research Summary

Mlcrostructure, Defects, Impurities,Atomic TransportThe research may be roughly classified as appliedsolid and liquid state physics; however with widecontact areas and numerous overlaps to other areasof materials science. Particular accent is placed on:atomic binding and mobility in condensed matter,point defects and extended defects; kinetics anddistributions of impurities; surfaces and interfaces.Research is pursued on different classes of materials(solid and liquid metals; semiconductors; ceramics;glasses; minerals; biological tissues) and aims toexplain electrical, thermal and mechanical proper-ties of matter in relation to microstructure andmicroanalysis. Applications extend into numerousdisciplines, ranging from basic solid state physics,physical metallurgy and semiconductor microelec-tronics, over chemical physics, analytical chemistryand nuclear engineering, into biomaterials, clinicalodontology, geo-cosmology and archaeometry.

A significant part of the activities is devoted todevelopment of advanced methodology in materialscharacterization, especially as based on interactionsbetween energetic ions and matter. The interdiscipli-nary rcsearchgroupisresponsiblefortheGothenburgSIMS-Laboratory, with Scandinavia's major heavyinstrumentation in multidisciplinarilyemployed sec-ondary ions mass spectrometry, used as a "nationalresource" in materials research. Consequently veryintensive interaction and collaboration exists withother laboratories, at universities and industries inSweden and abroad.

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31772 3430Fax 446 31 772 3436

StaffSenior MembersP.M. FischerM. FrieselA. LoadingH. OdeliusU. Södervall

Graduate StudentsJ.H. Wang.L.G. Persson

Technical StaffE.U. EngströmR. Sotkovszki

SecretaryH. Hast

docenttekn.drprofessorPh.Dtekn.dr

dipl. engineerodontlit.

research engineertechnician (part-time)

(part-time)

Major Instrumentation• Interdisciplinary SIMS, Cameca-Geologie

IMS-6F(1992).• SIMS ion probe-microscope, Cameca IMS-3F/

4F(1983).• Talysurf Profilometer.• Edwards Evaporator.• High pressure experimental plant, 15 kbar -

1500 K,Unipress (1991).• Metallurgic anneal furnace equipment.• Specimen preparation equipment: lapping,

polishing, microtome.• Several PC computers (HP)

Major Fields of ResearchA: Microstructure, element kinetics,

corrosion of metals, ceramics, glassesParticipants: U.Engström, A.Lodding, H.Odelius,O.Odawara, U.SödervallCollaborators: Max Planck Institut fur Metall-forschung, Stuttgart, Germany; Inst. f. Metall-forschung, Univ. Miinster, Germany, Inst. fiirMetallphysik, Techn. Universität Berlin, Germany;

26 THE CENTRE FOR

INTERDISCIPLINARY MATERIALS

Dept. of Materials Sci. & Eng., Univ. of Florida;Savannah River Laboratory, Aiken, SC: EnricoFermi Institute, Univ. of Chicago; Cameca SA,Courbevoie, France; Laboratory for Superconduc-tors, Physics Dept.,ChalmersUniv. Tech.; Sv. Kärn-bränslehantering AB, Stockholm.

B: Semiconductors; dopants & defects,Identification & kinetics

Participants: M. Friesel, A. Loading, H. Odelius, U.Södervall.Collaborators: Dept. of Solid State Electronics,Chalmers Univ. Tech.; Dept. of Physics & Measure-ment Technology, Univ. Linköping; Dept. of SolidState Physics, Univ. Lund; Max Planck Inst., Stutt-gart, Germany; SiTek AB, Mölndal, Sweden.

C: Geo-cosmology, Isotope geologyParticipants: U. Engström, A. Loading, H. Odelius,U. SödervallCollaborators: Dept of Geology, Chalmers Univ.Tech.; Dept. of Marine Geology, Univ. of Göteborg;Section of Mineralogy, Museum of Natural History,Stockholm.

D: Biomineralizations andbiocompatlble materials

Participants: P.M Fischer, A.Lodding, H.OdeliusCollaborators: Biomaterials Group, Dept. of Han-dicap Research, Univ. of Göteborg; Dept of Pedo-and Orthodontics, Univ. of Göteborg; Enrico FermiInstitute, Univ. of Chicago; Dept. of MaterialTechnica, Univ. of Groningen, Netherlands; Medi-cal & Dental Center, County Hospital, Halmstad,Sweden; Inst. for Post-Graduate Dental Education,Jönköping, Sweden.

E: Archaeometry, cultural environment;materials characterization

Participants: P.M. Fischer, M.Friesel, A.Lodding,H.OdeliusCollaborators: Scandinavian Archaeometry Center,Göteborg; Dept. of Musicology, Univ. of Göteborg;Dept of Pedo- and Orthodontics, Univ. of Göteborg.

F: Secondary Ion Mass Spectrometry(SIMS); mechanisms andmethodology

Participants: U.Engström, A.Lodding, H.Odelius,U.Södervall.Collaborators: Cameca SA, Courbevoie (France);Dept. of Analytical Chemistry, Univ. of Antwerp,Belgium; Dept. of Electronic Chemistry, TokyoInst. of Technology; Dept. of Materials Sci. & Eng.Univ. of Florida, Gainesville, FL; Enrico Fermi Inst.,Univ. of Chicago; AEA Industrial Technology,Harwell, UK.

Research ProjectsA: Microstructue, element kinetics,

corrosion

Al: Metals & alloysIn a continuing project, tracer diffusion and pointdefect studies have been performed on hep a-phasesof Group IV metals in wide temperature ranges.Secondary ion mass spectrometry is used for evalu-ation. Particular attention is given to isotope effects.Significant conclusions are drawn concerning in-trinsic as well as short-circuit type diffusion mecha-nisms.

Pilot microstructural and microanalytical investi-gations have been made on phase kinetics, grainboundary phenomena and impurity effects in refrac-tive metal composites, incl. tungsten heavy metals.

Continuing investigations are focused on atomictransport properties of liquid metals. Experimentsare conducted under gravity-free conditions(Spacelab), producing convection-free diffusion dataof unprecedented accuracy. Measurements in widetemperature intervals are indicative of a cooperativetransport mechanism. The energetics of elementaryatom displacements are further illuminated by thefirst ever obtained data on the isotope effect ofdiffusion in liquid metal.

A2: Ceramics & glassesIn systematic microstructural-microanalytic studiesof high-Tc superconductors and related mixed ox-ides, careful quantitation has been performed forSIMS characterization of numerous oxide phases.Applications have been performed on thin supercon-ducting layers in interaction with production envi-



p\.ment and substrate material under different con-ditions of heat treatment. Pilot studies have also beenmade of oxygen diffusion and environmental corro-sion in oxide superconductors.

Extensive studies have been made (and are con-tinued) of oxidic glasses, corroded in aqueous envi-ronment. SIMS in-depth profiling of the concentra-tion of up to 40 elements provides the tool to assessthe teachability of glasses of nuclear waste interest,and yields important information on the mechanismof corrosion in dependence of glass composition andleachant environment. Numerous such studies havebeen conducted for extended periods of time inlaboratory as well as in geological burial environ-ment.

B: Semiconductors; dopants & defects,identification & kinetics

The structures and mobilities of dopants and impu-rities have been investigated in silicon and germa-nium. Diffusivities have been measured (by SIMS ofstable isotopes) in very wide ranges of temperature(yielding activation energies), hydrostatic pressure(activation volumes) and diffusant mass (isotopeeffects). The concerted approach has yielded exten-sive information on the point defect configurationsand energetics, indicating several differential trans-port mechanisms. While vacancies appear to domi-nate diffusion in Ge, several impurities in Si are seento diffuse interstitially and/or by the participation ofself-interstitials.

Pilot studies are also being conducted on bondedSi layer structures and on stability in very highlydoped Si layers.

The focus of interest is gradually moving tolayered ni-V type semiconductor systems, incl dif-fusion effects at delta-layers and the mechanisms ofohmic contacts.

C: Gee-cosmology, isotope geologyPilot studies have been performed to chart the capa-bilities of SIMS in mineral dating by Pb isotopestudy of zircons. With new and particularly qualifiedSIMS equipment (acquired in 1992), main interesthas been placed on geological effects as manifestedin relatively light elements and isotopes (H, C, O,lanthanides). Present research is focused on a) iso-tope ratios of O and H in silicate minerals; b)

lanthanide ratios in minerals & rocks; c) isotoperatios of C and O in marine microfossils; and d) highresolution element distribution mappingof phases inminerals, incl meteorites. The collaborative projectof several laboratories, centered onSIMS methodol-ogy, is of interest in petrogenesis, geothermometry,hydrothermal transformations, ocean climatology,marine paleology, and cosmochemistry.

D: Biomineralizations andMocompatible materials

Collaborative research with medical, surgical andodontological groups in Sweden and Holland hasdirectly resulted in, or strongly contributed to, 4doctoral dissertations during the three most recentyears. By means of advanced SIMS, about 40 ele-ments in tooth and bone are charted 3-dimensionallyin concentrations down to 10 ppm or less. The workis directed on mineralization problems, with someaccent on the clinical role and kinetics of fluorine indental material, as well as the kinetics and toxiceffect of leakage elements from contact withbiomaterials, such as surgical implants and dentalfillings.

Pilot studies have been made on interface mor-phology, recovery phases and elemental interactionsat prosthetic implants in bone. Significant resultshave been obtained particularly on the leakage of Aland Ti from implant screws and on the topography ofthe restoring tissues.

Pilot studies have been performed on polymer-base fluoridized filling composites in interactionwith enamel and dentin; systematic investigaitons,in-vivo as well as in-vitro, are in progress.

E: Archaeometry, cultural environment;materials characterization

The archaeological interest has been strongly stimu-lated by the unique potentialities of SIMS in sensi-tive elemental and structural characterization ofinterdisciplinary materials. Within the program frameof the Scandinavian Archaeometry Centre, the tech-nique has been successfully exploited fordating andprovenance studies of materials from excavations inSweden, Greece, Cyprus and Jordan.

In acontinuing collaborative project, aimed at theconstruction of organ pipes closely reproductive of

28 THE CENTRE FOR


the tonal quality of famous baroque organs of NorthGermany and Holland, the chemical, microstructuraland mechanical properties of Pb-Sn alloys are beinginvestigated. The studies include ancient organ ma-terial from numerous churches as well as modemalloys, as-produced and aged. Particular accent isplaced on grain structures, distributions of impuri-ties, and surface effects. Collaboration takes placewith expertise in acoustics and musicology.

reproducible use of SIMS. The dependence of sec-ondary ion yield, from different matrices, on ionenergy, mass and other operational parameters hasbeen charted. Considerable instrumental improve-ments have been effectuated on existing instrumen-tation and subsequently also implemented on thelatest acquisition; particular progress was reached insuppressing the effects of charge build-up in quanti-tative SIMS profiling of insulating materials.

F: Secondary Ion Mass Spectrometry(SIMS)

Fl : National resource In materialscharacterization

The SIMS-Laboratory of the Chalmers Univ. ofTechnology has for more than a decade been estab-lished as a major facility in materials research con-ducted at universities and industries in Sweden andabroad. Applications take place both in collaborativeventures and in commercial contract work. Thenumber of laboratories/industries involved on aregu-lar basis during 1989-92 was about 40. The interna-tional status of the laboratory has brought involve-ment in multinational collaboration and standardisa-tion. The laboratory is presently coordinating aprogram on characterization of elements in softbiological tissues (particularly Al in brain tissues, inconnection with senile pathology). The CEC-BCRsupported project involves the participation of labo-ratories in Sweden, UK, Netherlands and Finland.

In 1992 the laboratory has entered a stage ofconsiderably expansive development, qualitativelyas well as quantitatively, due to the acquisition of asecond SIMS instrumentation, of a hitherto uniquedesign and with renderings radically superior tothose of earlier types of SIMS. The equipment(C meca-GéologieIMS-6F with "tailor-rmade" fea-tures) was financed by a grant (ca 8 million SwCr)from FRN and the Wallenberg foundation. It is runand organized by the interdisciplinary materialsresearch group under the administrative auspices ofa CTH-GU Supervising Committee and a NationalReference Group.

F2: Mechanisms of SIMS; methodologySystematic studies have revealed several mecha-nisms inherent in ionization by sputtering, and thushave significantly contributed to quantitative and

PublicationsDissertationsUlf Södervall, "Quantitative Applications of Secondary IonMass Spccttomctry", December 1991.

Reports and articles1. "Accelerated Leach Tests of SRL-165 HLW Glass in

Deionizcd Water", H.Kamizono, D.E.Clark,ALodding, J.NucI.Sci. & Tech. 26,1989, pp 441-448

2. 'Correlation of Laboratory and Stripa Leaching Studies".B.KZoitos, D.E.Clark, A.Lodding, G./G.Wicks, "TheScientific Basis for Nuclear Waste Management XII",(Lutzc <& Ewing, Eds.), Mat.Rcs.Soc. 127,1989, pp247-256

3. Effect of Topical F Solutions on Caries-Like Lesions atRoot Surfaces, T.Dérand, L.G.Pctcrsson, A.Lodding,Caries Res. 23,1989, pp 135-140

4. Fluorine Profiles in Human Enamel after In-VitroTreatment with Dentifrices of Different Compositionsand Acidities, L.G.Pctcrsson, A.Lodding, M.Hakcbcrg,G.Koch, Swed.DentJ. 13,1989, pp 177-183

5. Analysis of GaP-GaAsP Layered Structures,U.Södcrvall, M.R.Lcys, A.Lodding, L.Samuclsson,Surf.Interf.Analysis 12,1989, pp 555-558

6. Secondary Ion Mass Spectrometry of Cape York,E.U.Engström, Meteorilics 24,1989, pp 100-101

7. SIMS Studies of Teeth; a New Dating Technique?,P.M.Fischcr, A.Lodding "High Middle or LowChronology?" Stud. Mcditerr.Archaeol. & Litt. 80,1989, pp 142-149

8. Diffusion in Liquid Metals under Microgravity,G.Frohbcrg, K.H.Kraatz, H.Wcvcr, A.Lodding,H.Odclius, Defect & Diffusion Forum 66,1989, pp295-300



9. Activation Volumes of Impurity Diffusion in Silicon,U.Sodervall, A.Lodding, W.Gust, Defect & DiffusionForum 66,1989, pp 415-420

10. Marker Study of Surface Layer Formation and PartialDissolution, BJCZoitos, R.L.Schultz, D.E.Clark,ALodding, "Nuclear Waste Management" (Mellinger,Ed.), CeramTrans. 9,1990, pp 297-306

11. Quantitative Concentration Profiling and ElementBalance in SRL Glass after 2 Years in W1PP,ALodding, E.U.Engström, D.E.Clark, G.G.Wicks,Nuclear Waste Management" (Mellinger, Ed.),Ceram.Trans. 9,1990, pp 317-334

12. Atomic Transport of Trivalent Impurities in Silicon;Diffusion, Isotope Effects, Activation Volumes,U.Södcrvall, M.Fricscl, A.Lodding J.Chem.SocFaraday Trans. 86(8), 1990, pp 1293-1298

13. Quantitative SIMS of Superconducting Oxide Systems,E.U.Engsttom, ALodding, O.Odawara "SIMS VII"(Benninghoven & at. Eds.), Wileys, NY, 1990, pp7O5-708

14. MIIT International In-Situ Testing of Simulated HLWForms; Analyses of SRL165/TDS Waste Glass andMetal Systems G.G.Wicks, A.Lodding, P.B.Macedo,D.E.Clark, M.A.Molecke "High Level RadioactiveWaste Management I", Las Vegas, 1990, pp 443-450

15. Secondary Ion Mass Spectromctry in the Study ofBiomineralizations and Biomaterials, A.Lodding,P.M.Fischer, H.Odelius, J.G .Norén, L.Synnerby,C.B Johansson, J.M.Chabala, R.Levi-ScitiAnalyt.Chim.Acta 241(2), 1990, pp 299-314

16. International Round Robin Experiment for SIMSQuantification, F.G.Riidcnaucr, A.Lodding,USödervall & al. Pcriod.Polyiech. (Budapest) 34(1-3),1990, pp 73-80

17. SIMS Applications on Nuclear Waste Form,ALodding, D£.CIark, E.U.Engstrom, H.OdeliusM.Schumacher, G.G.Wicks. B.K. Zoitos, "CeramicsToday - Tomorrow's Ceramics" (Vincenzini, Ed.),Elsevier, Amsterdam, 1991, pp 3121-3129

18. High Quality YBCO Thin Films, Laser Deposition,Co-Evaporation, Device Fabrication, J. A. Alarco,G.Brorson, T.C.CIaeson, M.Danerud, E.U.Engström,Z.G.Ivanov, P.A.NiIsson, H.OIin, D.WinklerPhys.Scripta44,1991, pp 95-101

19. Elemental Concentration Profiles in an OxidizedSilicon Nitride Material, BL.K.L.Falk, E.U.EngströmJ.Amer.Cer.Soc. 74,1991, pp 2286-2292

20. Effect of High Pressure on Grain Boundary Diffusionduring Dis-Conlinuous Precipitation in Cu-In,M.Friesel, W.Lpjkowski, W.Gust, B.Prcdcl Dcf. &Diff. Forum 75,1991, pp 229-237

21. "Quantitative Applications of Secondary Ion MassSpectrometry; Solid State Diffusion and Mass Fractio-nation Study", U.Södervall Tekn.dr. Thesis, CTH, 1991

22. SIMS Studies of Archaeological Materials,P.M.Fischer, H.Odelius, A.Lodding Laborativ Arkeol.5,1991, pp 209-214

23. Surface Analysis of SRS Waste Glass Buried for up toTwo Years in Limestone in the UK, G.CNamboodri,SL.Mamboodn, G.G.Wicks, A.Lodding, L.L.Hench,DECIark, R.G.Newton, 'Ceramics in Nuclear &Hazardous Waste Management", US Ccr.Soc.,Cincinnau, 1991

24. Analysis of SRS Glass Buried in Granite in Swedenand Salt in the United Slates, J.P.Williams, G.G.Wicks,D.E.Clark, A.Lodding "Ceramics in Nuclear &Hazardous Waste Management", US Ccr.Soc.,Cincinnati, 1991

25. Surface Modification of Sodium AluminosilicaicGlasses Using Microwave Energy, D.Fathi, I.Ahmed,J.H.Simmons, D.E.Clark, A.Lodding "Microwaves;Theory & Application in Materials Processing"Ceram.Trans. 21,1991, pp 623-629

26. Characterization of Corroded Ceramics by SIMS,ALodding Ch. 4 in "Corrosion of Glasses, Ceramicsand Ceramic Superconductors" (Clark & Zoitos, Eds.),Noyes Publ., Park Ridge NJ, 1992, pp 103-121

27. Tissue Reactions in Ti-Al-V-AHoy, C.B Johansson,T.Albrektsson, P.Thomsen, L.Sennerby, A.Lodding,ROdelius, EurJ.MuscoIoskel.Rcs. 5,1992, pp 135-236

28. Isotope Effects of Atomic Transport in Metals,ALodding, J.NucI.Sci & Eng., 1992, pp 472-477

29. In-Situ Testing of Simulated HLW Forms in Saltduring 5 Year Burial, G.G.Wicks, A.Lodding,P.B.Macedo, D.E.Clark,, "Scientific Basis for NuclearWaste Management XV", 1992

30. Long Term Field Leaching Studies of Nuclear WasteGlass in Granite and Salt, R.L.Schukz, D.E.Clark,A.Lodding, G.G.Wicks,, "Scientific Basis for NuclearWaste Management XV", 1992

30 THE CENTRE FOR


31. Measurements of Isotopic Ratios; Influence of Instru-mental Variables, U.Sodcrvall, A.M.Adrcaens,AIxdding, E.U.Engström, H.Odelius, F.Adams, SIMSVIII" (Benninghoven & Al, Eds.), J.Wiley & Sons,NY, 1992, pp 81-84

32. Elemental Depth Profiling of Nuclear Waste Glassesafter Two Years Burial in a Salt Geology, A.Lodding,E.U.Engström, B.ICZoitos, D£.Ciark,JAmer.Cer.Soc. 75,1992, pp 1238-1249

33. Volume Diffusion of Titanium in a-Hafnium SingleCrystals., M.Köppers, Chr.Herzig, U.Sodervall,ALodding, DIMENTA, Japan, 1993, in press

34. A Swedish Nuclear Waste Glass after Eight Years ofLeaching in the Stripa Mine, L.O.Werme, H.Odelius,A lidding, "In-Situ Testing of Radioactive WasteForms and Engineered Barriers" (McMenamin, Ed.),CEC-EUR, 1993, in press

35. Leachabilities of International Waste Glasses in WIPP,ALodding, DJa.Clark, G.G.Wicks "In-Situ Testing ofRadioactive Waste Forms and Engineered Barriers",(McMenamin, Ed.), CEC-EUR, 1993, in press


Experimental Physics

Research SummaryResearch is conducted on a wide range of materialswith interesting optical, electrical and structural prop-erties. The work iseitheroffundamental character ororiented towards technical applications.

The research is focused on solid state physics andalso includes components of materials science withemphasis on thin film coating technology. Certainprojects embrace (electrochemistry, meteorologyand technology in a broad sense. Many of the projectsare chosen so that they elucidate salient issues relatedto energy efficiency and energy production and, atleast in some cases, have led to the establishment ofnew important materials, and new concepts, forenergy efficient architecture. Industrial aspects andThird World issues are relevant for some of theresearch.

Coatings with selective optical properties, ob-tained through microstructural control, have been infocus for much of the research during the past severalyears. Thus we have studied heavily doped oxidesemiconductors with spectrally selective transmit-tance and established quantitative models for theirproperties. Coatings with angular-selective trans-mittance have been developed by exploiting specialthin film techniques with oblique incidence of theevaporated flux.

Much attention has been devoted to electro-chromic materials and electrochromics-based de-vices. The latter work embraces electrochromic ox-ide coatings with mixed conduction for ions andelectrons, purely ion conducting materials includingnovel transparent adhesive polymer electrolytes,and ion-storage coatings with some electronic con-ductivity. New materials with temperature-depend-ent semiconductor-metal transition have beeninvestigated with the goal of obtaining coatings withthermochromic switchingaroundroom temperature.

Considerable effort has been devoted to basicstudies of disordered materials, with emphasis ontheir dielectric response (ac conductivity). A powerlaw behaviour of the ac conductivity of amorphoussemiconductors and insulators as well as ionic con-

32

ductors has been interpreted in terms of conductionon fractal structures and fractal time processes. Theexperimental studies encompass a broad range ofmaterials. Recently our dielectric studies have beenextended to water saturated porous materials as well.

Dielectric coatings, pigments, and other materi-als are studied with the aim of developing materialsfor passive radiative cooling applications.

The ion transport has been studied in a number ofmaterials; inorganic salts, polymer electrolytes andhigh-temperature superconductors. New high-tem-perature protonic conductors have been developedand fuel cells for the medium temperature range havebeen constructed.

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31 772 3345Fax +46 31 3367

S t a f f (January 1993)

Senior MembersClaes G Granqvist professorBengt-Erik Mellander docentGunnar A Niklasson docentAnne A Andersson tekn drAndris Azens PhD (Latvia)Bertil Stjerna fil dr

Graduate StudentsIngvar AlbinssonZhu BinRafi GåttAbel GutarraJan IsidorssonGodfrey MbiseBo NettelbladTorbjörn NilssonSteve Palmer

civ.ing.M.Sc. (China)B.Sc. (Israel)M.Sc. (Peru)civ.ing.M.Sc. (Tanzania)civ.ing.civ.ing.M.Sc. (UK)

THE CENTRE FOR

EXPERIMENTAL PHYSICS

Technics StaffSören Nasenius

SecretariesMarita AhlkvistIngrid Riedl

(50%)civ.ing.

(20%)(50%)

Major Instrumentation• Magnetron sputtering unit for thin film deposi-

tion. (Substrates up to 5 x 5 cm2; rf and/or dcsputtering from up to four sources simultane-ously; non-reactive or reactive deposition withup to three individually regulated g?ses; ar-rangements for work with fluorine-containinggases; rotatable substrate fixturing; substrateheating up to 800°C; UHV-compatibility;load-lock for easy and rapid access).

• Magnetron sputtering unit for thin film deposi-tion. (Substrates up to 50 x 50 cm2; rf and/or dcsputtering from up to two sources simultane-ously; non-reactive or reactive deposition withup to three individually regulated gases; ar-rangements for work with fluorine-containinggases; rotatable or linearly moving substratefixturing; substrate heating up to 800°C forsmall stationary substrates).

• E-beam evaporation unit for thin film deposi-tion (up to 2 individually controlled sources;facility for ion bombardment during deposi-tion; shared facility).

• Film thickness monitor (Alfa-step R&D 200).• Spectrophotometers for 0.2-2.5 |im wave-

length with integrating sphere, specular reflect-ance attachments, polarizers.

• Spectrophotometer for 2.5 - 50 )im wave-length with specular reflectance attachments,polarizers.

• Dielectric spectrometer for 104 - 104 Hzfrequency range.

• Electrochemical interface.• Dry-lab (glove box).• Spectroradiometer (array detector).• Thermal analysis equipment; differential

thermal analysis, differential scanningcalorimetry, dilatometer

• High temperature X-ray diffractometer

• Complex impedance analysers, electrometer• High pressure equipment (gaseous pressures

up to 1 GPa) for electrical and thermal analysismeasurements.

The equipment can be made available to externalusers by commercial agreement with CoAT AB,Datavägen 21B, 436 32 Askitn.Contact person: CG. Granqvist, 031-772 33 55.

Major Fields of ResearchA: Optical Properties of Strongly Doped Semi-

conductors: Spectrally Selective Thin Films.Participants: CG. Granqvist, B. Stjerna.

B: Chromogenics.Participants: CG. Granqvist, G.A. Niklasson,A.M. Andersson, A. Azens, A. Gutarra,J. Isidorsson, S. Palmer.Collaborators: CoAT AB, Askim (Sweden), U.Guelph (Canada), U. Rome (Italy), U.Campinas (Brazil), UNI, Lima (Peru), U.Rajshahi (Bangladesh) Tsinghua U. (China).

C: Electromagnetic Properties of Granular Matterand Fractal Structures.Participants: G.A. Niklasson, CG. Granqvist,R. Gått, B. Nettelblad.Collaborators: ABB Research and Develop-ment, Dept. of Building Materials (CTH),Dept. of Theoretical Physics (CTH), Dept. ofGeology (CTH).

D: Ion Conductors and Materials for Fuel Cells.Participants: B.-E. Mellander, I. Albinsson,Z.BinCollaborators: U.Guelph (Canada), U. Pera-deniya (Sri Lanka), U. del Valle (Colombia),Dept. of Phys. and Chem. U. of Uppsala, DSIR(New Zealand), Oslo U. (Norway), Odense U.(Denmark).

E: Materials and Devices for Radiative Coolingand Condensation Irrigation.Participants: CG. Granqvist, G.A. Niklasson,T. Nilsson.



Research Projects

A: Optical Properties of StronglyDoped Semiconductors:Spectrally Selective Thin Rims.

Thin films of wide-bandgap semiconductors wereproduced by reactive evaporation and reactive sput-ter technology. Doping, up to several percent, wasobtained by codeposition. Extensive studies werecarriedoutforIn2O3:Sn,Zn0:Al,Sn0xandSn02(Sb,F), most recently with a focus on the Sn-based films.The materials were characterized by spectro-photometry in 0.2-50 nm wave-length range, elec-trical measurements, Hall effect determinations,Mössbauer spectrometry, electron microscopy andX-ray diffraction. A consistent theoretical modelwas formulated. It allowed quantitative calculationsof the optical properties.

With regard to applications, some of th • materialsin this project give an unsurpassed combination ofhigh short-wavelength transmittance and high long-wavelength reflectance (and concomitant low ther-mal emittance and electrical resistivity). Hence theyare useful as transparent electrodes - for example inelectrochromic devices - as well as for windowcoatings that transmit solar energy with little emis-sion of thermal radiation.

B: Chromogenics

Bl: Electrochromic Materials and SystemsThe systems studied in this project include anelectrochromic layer in contact with an "electrolyte"and an "ion storage" layer. The electrolyte shouldhave purely ionic conduction, whereas the other twolayers should have mixed conduction for ions andelectrons. The basic similarity to thin film batteriesshould be noted. The configuration is placed be-tween transparent and electrically conducting layerssuchasIn2O3:Sn(see project A). Among the electro-chromic materials, extensive work has been carriedout for the oxides of tungsten, nickel, vanadium andniobium. Work has been begun for oxides of tita-nium and tin. These materials are characterized byspectrophotometry, cyclic voltammetry, impedancespectrometry, electron microscopy, X-ray diffrac-tion, Rutherford backscattering and nuclear reactionanalysis. Detailed theoretical models of the optical

ELECTROCHROMICDEVICE

Mi'

Electrochromic device

properties have been formulated. A unique solvent-free Li+-conducting non-hygroscopic adhesive poly-mer electrolyte was developed through cooperationwith the University of Guelph, Canad;1: v!ic materialis based on acopolymerof polymethyl m^iiacrylateand polypropylene glycol and is made ion conduct-ing by the addition of lithium triflate. An ion conduc-tivity as high as ~ 10"4 S/cm was recorded at roomtemperature.

B2: Thermochromlc MaterialsThermochromic thin films were studied with a focuson vanadium oxide-based materials. Pure VO2 un-dergoes a reversible metal-insulator transition, withan associated abrupt change of the optical properties,at 68°C. This material, as well as WyV^C^ andVOxFy with depressed transition temperature, wereprepared by reactive sputtering. Optical and electri-cal properties were determined. The materials werecharacterized by electron microscopy and Rutherfordbackscattering. Fundamental issues connected withmetal-insulator transitions, as well as potential win-dow-related applications, have been investigated.

34 THE CENTRE FOR


C: Electromagnetic Properties ofGranular Matter and FractalStructures

C l : Optical Properties of MetaHnsulatorComposites and InhomogeneousMetal Films

The dielectric permeability of a composite, withinhomogeneities much less than the wavelength ofelectromagnetic radiation, can be described by ef-fective medium theories. We have extended effec-tive medium theories to include information on thepair and three-point correlation functions of theinhomogeneities. Calculations of the optical proper-ties of fractal clusters have been performed. A theo-retical framework for optically anisotropic absorb-ing composites has also been developed.

Experiments on metal-insulator composites, gasevaporated metal particles and thin metal films witha columnar structure are well described by thesetheoretical models. Analyses based on effectivemedium theories also has enabled us to shed light onthe degradation of the absorption in solar collectorsurfaces, and lifetime predictions have become fea-sible as a result of this work. Retarded oxidationkinetics in cermet materials with ultrafine metalparticles has been discovered.

Thin metal films with a columnar microstructureshow angular selectivity of the optical properties andare of potential interest for applications on solarcontrol windows. Thin films of silver, aluminiumand chromium have been produced by evaporation

at an oblique angle of incidence. The columnarmicrostructure has been characterized by high reso-lution electron microscopy. The optical propertiesare qualitatively described by the theory foranisotropic composites referred to above. Anotherstudy has concerned the optical properties of thinmetal network films close to the metal-insulatortransition.

C2: Optical Properties of Materialswith Large Inhomogeneities

The optical properties of materials with inhomo-geneities comparable to or larger than the wave-length of light can be described by multiple scatter-ing theory. We have shown that the four-flux theoryis a useful and accurate approximation in manypractical situations. An experimental programme onthe optical properties of strongly scattering materialsis in progress. The specular and diffuse reflectance aswell as the direct and diffuse transmittance are beingmeasured. We have studied quartz fibres immersedin CCI4, pigmented polymers, water saturated po-rous glasses and inhomogeneous biological materi-als. Polymer foils containing inorganic pigments areof interest for radiative cooling applications (Seeproject E).

C3: Electrical Properties of dielectric Materials

The electrical properties of ir ..ulating coatings werestudied both from the basic physics point of view andbecause of applications in the field of electricalinsulation. We have measured the ac dielectric re-

ta) PAr» 0.25 Torr (b) PAf« 3 Torr (c) PAr«1O Torr

Gas-evaporated nickel particles. Note the different states of aggregation.



sponse in the frequency range KH-107 Hz as well ascurrent-voltage characteristics and, in some cases,electroluminescence of visible light for a wide rangeof materials. They include CO-AI2O3 composites,amorphous AI2O3, SiO2 and SiOxNy coatings, anAgl-based composite ionic conductor, and pyroly zedpolyimide. The commonly observed power lawbehaviour of the dielectric permittivity has beeninterpreted in terms of conduction on fractal struc-tures and fractal time processes. For cases wheredifferent dielectric response functions can be distin-guished, the Davidson-Cole expression appears togive the best fit to our measurements. The dielectricspectroscopy technqiue has also been applied to thestudy of electrochromic hydrated nickel oxide filmsas well as of ZnO based varistor materials, which areof interest for protection of electrical equipmentagainst transient overvoltages.

C4: Electrical Properties of Porous MatelraisA study of the ac electrical properties in the fre-quency range l(H-107 Hz of various cement mor-tars was carried out in collaboration with the Depart-ment of Building Materials, CTH. Measurementswere repeated periodically after the preparation ofthe samples. The dependence on water content wasfurther studied by subjecting the samples to heattreatments. Our measurements gave evidence for apercolation threshold at very low water contents.The frequency dependence of the dielectric responsewas consistent with the assumption of a fractal poresurface. Structural parameters were extracted fromadsorption isoterms.

Presently the electrical properties of porous sam-ples of glass beads and sand glued together withepoxy are being studied in collaboration with theDepartment jf Geology. The conductivity has beendetermined as a function of the conductivity of thesalt solution introduced into the pores.

C5: Characterization of Fractal StructuresWe have developed a method for determining thefractal dimension by measurements of the pair cor-relation function of aggregated particles seen inelectron micrographs. The influence of projectioneffects has been modeled in collaboration with theInstitute of Theoretical Physics at CTH. Furtherwork on multifractal characterization is under way.These methods have been applied to study aggrega-

tion of gas evaporated metal particles. It was foundthat aggregates of nonmagnetic particles had a fractaldimension of 1.9-2, while aggregates of ferromagneticCo particles showed fractal dimensions in the range1.35-1.6. These results are in qualitative agreementwith simulations using cluster-cluster aggregation.

D. Ion Conductors and Materialsfor Fuel Cells

We have studied ion transport in inorganic com-pounds and polymer systems. A large number ofmaterials with high ionic conductivity have beenstudied. It has e.g. been shown that the increasedionic conductivity in two-phase materials can berelated to the grain growth during the phase transi-tion in eutectic or eutectoid systems. Computersimulations as well as experimental determination ofphase diagrams have also been performed. Thetransport-structure relation for ion conducting poly-mers has been investigated by several techniquesand it has been shown that the ion association is animportant factor for the ionic conductivity in lowpermittivity polymers. We have also determined the

(A)CH3 CH3 CH3 CH3I I I I

H3C-Si-O-(-Si-O-)x-(-Si-O-)y-Si-CH3

I ICH3 CH3

x = 6, y = 8, N = 7.5

CH3

(B)

One of the ion conducting polymers that have beenproduced is based on the polymer PECVPDMS(A)doped with Li CF3SO3; the anion is shown in (B).

36 THE CENTRE FOR


electrical relaxation of the ion pair and discussed thepercolation effects on the ionic conductivity. Theoxygen self-diffusion coefficient in RBa2Cu3(>7-5(R=Y, La, Nd,...) high-temperature superconductorshas been determined using mechanical relaxationmeasurements of the oxygen hopping in the basalchain layer. The results offers a practical solution tothe problem of slow oxygen diffusion in singlecrystal and bulk materials such as wires and melt-textured monolithic bodies. Completely new typesof proton conducting solid electrolytes have beendeveloped and fuel cells using these electrolyteshave been constructed for use in the temperaturerange 500 to 800°G

E. Materials and Devices for RadiativeCooling and Condensation Irrigation

Passive radiative cooling is possible by infraredemission towards the clear sky. In earlier work westudied silicon oxynitride coatings, as well as certaingas layers, for this applica.ion. Presently, solar-reflecting infrared-transparent foil materials are be-ing developed by exploiting multiple scatteringtheory. In a more applied project, we investigatecooling devices for condensation irrigation in aridregions. This project is performed in collaborationwith groups in Africa. So far, up to -0.4 litres ofwater has been obtained per night, which is sufficientfor establishing growing plants.

Publications

Ph.D. DissertationsA.M. Andersson, "Elcctrochromic Materials: Optical,

Electrophysical and Structural Properties", 1992.

W. Estrada, "Electrochromic dc Sputtered Nickel-oxide-based films: Optical Structural, and ElectrochemicalCharacterization" (Lima, Peru, 1990; sandwichprogram).

K. Khan, "Electrical and Optical Properties of VanadiumDioxide and Vanadium Oxyfluondc ThermochromicThin Films, and Their Applications to Energy EfficientSmart Windows" (U. Rajshahi, Bangladesh, 1989;sandwich program).

B. Stjema, "Electrical and Optical Properties of Doped TinOxide Films", 1992.

A. TaJIedo, "Vanadium Pcntoxide-bascd Thin Films:Optical, Structural, and Electrophysical Characteri-zation" (Lima, Peru, 1992; sandwich program).

Licentiate DissertationsA.M. Andersson, "Optical, Electrochemical and Structural

Characterization of Elcctrochromic Thin Film SystemsBased on Oxides of Nickel, Tungsten and Vanadium",1990.

G. Mbise, "Angular-selective Window Coatings: SomeTheoretical and Experimental Studies" (M.Sc, U. Dares Salaam, Tanzania, 1989; sandwich program).

T. Nilsson, "Optical and Electrical Properties of SomeInhomogeneous Materials Used for Energy EfficientApplications", 1990.

B. Stjema, "Electrical and Optical Properties of Non-stoichiometric Tin Oxide Films", 1990.

Diploma WorkA. Berg, "Diclcktriska egenskaper hos betong", 1989.

C. Edgrcn, "Värmcblockcrandc glas: Kupéklimaictspåverkan av spcktralselcktiva glas", 1991.

A. Lamm, "Tunna tellurfilmcr på polyeten somkonvektionssköld för strålningskylning", 1991.

A. Books, compendia andproceedings volumes

1. CG. Granqvist, Spectrally Selective Surfaces forHeating and Cooling Applications (SPIE Opt. Engr.Press, Bcllingham, 1989), Vol. TT1,120 pages.



2. C.G.Granqvist and CM. Lampert, editors, OpticalMaterials Technology for Energy Efficiency and SolarEnergy Conversion VIII (SPIE Opt. Engr. Press,Bellingham, USA, 1989), 208 pages.

3. CG. Granqvist and CM. Lampert, editors. OpticalMaterials Technology for Energy Efficiency and SolarEnergy Conversion IX (SPIE Opt. Engr. Press,Bellingham, USA, 1990). 318 pages.

4. C.G.Granqvist and G.A. Niklasson, Thin FilmTechnology: Compendium for a Course given atChalmers University of Technolgy (1990), 307 pages.

5. CM. Lampert and C.G.Granqvist, editors, Large-areaChromogenics: Materials and Devices for Transmit-tance Control (SPIE Opt Engr. Press, Bcllingham,USA, 1990), 606 pages.

6. CG. Granqvist, editor, Materials Science for SolarEnergy Conversion Systems (Pergamon, Oxford, UK,1991), 203 pages.

7. CM. Lampert and C.G.Granqvist, editors, OpticalMaterials Technology for Energy Efficiency and SolarEnergy Conversion X (SPIE Opt. Engr. Press,Bellingham, USA, 1991), 298 pages.

8. A. Sobhan and CG. Granqvist, guest editors, SolarEnergy Materials and Solar Cells, Vol. 28, No. 2(1992), pp. 103-193.

9. CG. Granqvist, Electrochromic Oxides: Thin Filmsand Devices (Elsevier, Amsterdam, The Netherlands)(to be published).

10. CG. Granqvist, A. Hugot-LcGoff and CM. Lampcrt,editors, Optical Materials Technology for EnergyEfficiency and Solar Energy Conversion XI: SelectiveMaterials, Reflectors, Concentrators, TransparentInsulation and Super Windows, Proc. SPIE 1727 (to bepublished).

11. CG. Granqvist, A. Hugot-LeGoff and CM. Lampert,editors, Optical Materials Technology for EnergyEfficiency and Solar Energy Conversion XI:Chromogenics for Smart Windows, Proc. SPIE 1728(to be published).

11 CG. Granqvist, A. Hugot LeGoff and CM. Lampcrt,editors, Optical Materials Technology for EnergyEfficiency and Soiai Er.?nsy Conversion XI: Photovol-taics, Photochemistry and Photoclectrochemistry, Proc.SPIE 1729 (to be published).

B. Reviews1. CG. Granqvist, Materials for Energy Efficiency andSolar Energy Conversion: Some Examples, in Work-shop on Materials Science and the Physics of Non-conventional Energy Sources, eds. G. Furian, D.Nobili, A.M. Sayigh and B.O. Scraphin (WorldScientific, Singapore, 1989), pp. 1-44.

2. CG. Granqvist, Energy-Efficient Windows: Optionswith Present and Forthcoming Technology, in Electric-ity: Efficient End Use and new Generation Technol-ogy, and Their Implications for Electric Utility Plan-ning and Policy, eds. T.B. Johansson, B. Bodlund andR.H Williams (Lund University Press, Lund, Sweden,1989), pp. 89-123.

3. CG. Granqvist, Kromogena Material i Smarta Fönster:Möjligheter och Utmaningar (Chromogenic Materialsin Smart Windows: Possibilities and Challenges),Byggforskning, November 1989, pp. 30-32; also inByggvarunylt 1/1990, pp. 16-18; excerpt in Mckanisten1990:1, p. 60.

4. B.-E. Mcllander, Polymer solid electrolytes, in SolidState Physics-1, eds. M.A.K.L. Dissanayake, R. Attelcand K. Tcnnakone (Nova Science Publishcrs.Inc, NewYork, 1989), p. 193-200.

5. CG. Granqvist, Optical Properties of Granular Materi-als: How to Model Coatings for Energy-efficientWindows, in Physical Phenomena in Granular Materi-als, edited by G.D. Cody, T.H. Gcballc and P. Sheng,MRS Symp. Proc. 195,37-52 (1990).

6. CG. Granqvist, Window Coatings for the Future, ThinSolid Films 193/194,730-741 (1990).

7. CG. Granqvist, Solar Energy Materials: The Role ofResearch and Development, in Energy and the Envi-ronment into the 1990s, cd. A.A.M. Sayigh (Pergamon,Oxford, 1990), Vol. 3, pp. 1465-1475; also in Proc.Conf. on Energy and Environment, Riga, Latvia, 13-17May 1991, pp. 352-362.

8. CG. Granqvist, Chromogenic Materials for Transmit-tance Control of Large-area Windows, Crit. Rev. SolidState Phys. Mater. Sci. 16,291-308 (1990); also inProc. Workshop on Materials Science arid Physics ofNon-conventional Energy Sources (World Scientific,Singapore, 1991), pp. 143-199.

9. CM. Lampert and CG. Granqvist, Introduction toChromogenics, in Large-area Chromogenics: Materialsand Devices for Transinittancc Control, eds. C.M.Lampert and CG. Granqvist (SPIE Opt. Engr. Press,Bcllingham, 1990), pp. 2-19.

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10. CG. Granqvist, Introduction to Materials Science forSolar Energy Conversion Systems, in MaterialsScience for Solar Energy Conversion Systems, ed.CG. Granqvist (Pergamon, Oxford, 1991), pp. 1-6.

11. CG. Granqvist, Energy-efficient Windows: Optionswith Present and Forthcoming Technology, in Materi-als Science for Solar Energy Conversion Systems, ed.CG. Granqvist (Pergamon, Oxford, 1991), pp. 106-167.

12. C.G.Granqvist and T.S.Eriksson, Materials forRadiative Cooling to Low Temperatures, in MaterialsScience for Solar Energy Conversion Systems, ed.CG. Granqvist (Pergamon, Oxford, 1991), pp. 168-203.

13. CG. Granqvist, Materials for Energy-Efficient Win-dows: New Coatings with Spectral and AngularSelectivity, Proc. Workshop on Materials Science andPhysics of Non-conventional Energy Sources (WorldScientific, Singapore, 1991), pp. 87-141.

14. CG. Granqvist, Semiconductor-based Coatings forEnergy Efficiency and Solar Energy Applications, inSemiconductors and Rare Earth Based Materials, eds.CAJ. Ammcrlaan, F.F. Becker, JJ.M. Frånse, NguyenVan Hieu and Than Due Hien (World Scientific,Singapore, 1991), pp. 122-138.

15. G.A. Niklasson, Optical Properties of InhomogeneousTwo-phase Materials, in Materials Science for SolarEnergy Conversion Systems, edited by CG. Granqvist(Pergamon, Oxford, 1991), pp. 7-43.

16. G.A. Niklasson and CG. Granqvist, Selectively Solar-absorbing Surface Coatings: Optical Properties andDegradation, in Materials Science for Solar EnergyConversion Systems, ed. CG. Granqvist(Pergamon, Oxford, 1991), pp. 70-105.

17. B.-E. Mellander, I. Albinsson and J.R. Stevens, Iontransport mechanisms in polymer electrolytes at normaland high pressure, in: Frontiers of High-PressureResearch, Eds. H.D. Hochhcimer and R.D. Etters(Plenum Press, New York, 1991), p. 17-23.

18. CG. Granqvist, Elcctrochromic IR Coatings: Proper-ties, Prospects and Problems, Proc. SPIE Vol. CR 39,156-178(1992).

19. CG. Granqvist, Elcctrochromism and Smart WindowDesign, Solid State Ionics 53-56,479-489 (1992).

20. CG. Granqvist, Solar Energy Materials: Survey andSome Examples, in Surface Science: Lectures on BasicConcepts and Applications, Springer Proc. Phys., eds.F.A. Ponce and M. Cardona (Springer, Berlin,Heidelberg, 1992), Vol. 62, pp. 237-248.

21. CG. Granqvist, Electrochromic Coatings for SmartWindows: A Status Report, in Renewable Energy:Technology and the Environment, edited by A.A.M.Sayigh (Pergamon, Oxford, 1992), pp. 114-123.

22. CG. Granqvist, Electrochromic Thin Films, in OpticalInterference Coatings, Optical Society of AmericaTechnical Digest Series, Vol. 15, p. OMA 3-1/5(1992).

23. CG. Granqvist, Electrochromics and Smart Windows,Solid State Ionics, to be published.

24. CG. Granqvist, Principles of Electrochromic Devices,Proc. Ini School of Materials Sci. Tcchnol., to bepublished.

25. CG. Granqvist, Transparent Conductive Electrodes forElcctrochromic Devices, Proc. Int. School of MaterialsSci. Tcchnol., to be published; also in Appl. Phys., tobe published.

26. CG. Granqvist, Eleclrochromic Tungsten-oxide-basedThin Films: Physics, Chemistry and Technology, inPhysics of Thin Films, cd. J. Vossen (Academic, SanDiego, 1993), to be published.

27. G.A. Niklasson, Elektricitet och fraktaler, KOSMOS1992: pp. 103-118.

C. Original Scientific Papers1. A.M. Andersson, CG. Granqvist and J.R. Stevens, An

Electrochromic LixWO3/polymer electrolyte/Li^OsDevice: Towards an All-solid-state Smart Window,Appl. Opt. 28,3295-3302 (1989).

2. T. Farestam and G.A. Niklasson, Projection Effects inElectron Micrographs of Three-dimensional FractalAggregates: Theory and Application to Gas Evapo-rated Speciments, J. Phys. Cond. Matter. 1,2451-2463(1989).

3. T. Farestam, G.A. Niklasson, A. Torebring, C. Larssonand CG. Granqvist, Fractal Structure of Gas Evapo-rated Metal Aggregates, Physica A 157,49-52 (1989).

4. K.A. Khan and CG. Granqvist, ThermochromicSputter-deposited Vanadium Oxy fluoride Coatingswith Low Luminous Absorptancc, Appl. Phys. Lett.55,4-6(1989).

5. G. Mbise, G.B. Smith and CG. Granqvist, HighResolution Studies of Columnar Growth in ObliquelyDeposited Metal Films on Glass, Thin Solid Films 174,L123-L127(1989).



6. G. Mbise, G.B. Smith, G.A. Niklasson and CG.Granqvist, Angular-Selective Optical Properties of CrFilms Made by Oblique-angle Evaporation, Appl.Phys. Utt. 54,987-989 (1989).

7. G.A. Niklasson, Applications of InhomogencousMaterials: Optical and Electrical Properties, Physica A157,482-488(1989).

8. G.A. Niklason, Comparison of Dielectric ResponseFunctions for Conducting Materials, J. Appl. Phys. 66,43504359(1989).

9. G A. Niklasson, Effective Medium Theories with Pairand Three-Point Correlation Effects, Physica A 157,364-367(1989).

10. G.A. Niklasson, Fractals and the ac Conductivity ofDisordered Materials, Physica D 38,260-265 (1989).

11. G.A. Niklasson, K. Brantervik and T.S. Eriksson,Dielectric Properties of Disordered Insulators, PhysicaA 157,520-523 (1989).

12. G.A. Niklasson, T.S. Eriksson and K. Brantcrvik,Dielectric Properties of Silicon Oxynitride Films, Appl.Phys. Lett. 54,965-967 (1989).

13. S. Passerini, B. Scrosati, A. Gorenstein, A.M.Andersson and CG. Granqvist, An ElcctrochromicWindow Based on NiO/(PEO)g LiCIO4/WO3.J. Electrochem. Soc. 136,3394-3395 (1989).

14. P.A. Svantesson, I. Albinsson and B.-E. Mellandcr, Ionconducting phases in the poly(propylcnc glycol) -poly(methyl methacrylaie) - L1CF3SO3 systems, Z.Naturforsch.44a, 1231-1233 (1989).

15. P.W.S.K. Bandaranayake and B.-E. Mcllandcr, Phasetransitions and ionic conductivity of the Na2SO4-MgSO4 system, Solid State Ionics 40/41,31-33 (1990).

16. K. Brantervik, A. Berg, G.A. Niklasson, B. Hedbergand L.O. Nilsson, Percolation Effects in the ElectricalConductivity of Porous Cement Mortar, Europhys.Lett. 13,549-554(1990).

17. A. Gorenstein, F. Decker, W. Estrada, S. Passerini, S.Pantaloni and B. Scrosati, Electrochromic NiO,Hy

Hydrated Films: Cyclic Voltammctry and ac Imped-ance Spectroscopy in Aqueous Electrolyte, J. Electro-anal. Chem. 277,277-290 (1990).

18. U. Kreibig, K. Fauth, CG. Granqvist and G. Schmid,6s-Electrons in Stabilized Au55-Clusters, Z. Phys.Chem.N.F. 169,11-28(1990).

19. B.-E. Mcllander and C.-A. Sjöblom, Computer aidedevaluation of the p-T phase diagram of Agl usingthermodynamic data, High Pressure Research, 4,517-519(1990).

20. B.-E. Mellander, B. Granéli and J. Roos, Ionic conduc-tivity of single crystal LiNaSO4l Solid State Ionics 40/41,162-164(1990).

21. B. Stjcma and CG. Granqvist, Electrical Conductivityand Optical Transmittance of Sputter-deposited SnO,Thin Films, Solar Energy Mater. 29,225-233 (1990).

22 B.Stjerna and C.G.Granqvist, Optical and ElectricalProperties of SnOx Thin Films made by Reactive RFMagnetron Sputtering, Thin Solid Films 193/194,704-711(1990).

23. B. Stjcrna and CG. Granqvist, Transparent ConductingSnO, Films High-rate Reactively Sputtered ontoPolyester Foil, Appl. Opt. 29,447-448 (1990).

24. B. Stjema, CG. Granqvist, A. Scidcl and L. Häggström,Characterization of RF Sputtered SnOx Thin Films byElectron Microscopy, Hall Effect Measurement, andMössbaucr Spcctrometry, J. Appl. Phys. 68,6241-6245(1990).

25. A. Tallcdo, A.M. Andersson and CG. Granqvist,Electrochromically Lithiated V2O5 Films: An Opti-cally Passive Ion Storage for Transparent Electro-chromic Devices, J. Mater. Res. 5,1253-1256 (1990).

26. I. Albinsson, B.-E. Mellander and J.R. Slevens, Ionicconductivity in polyethylene oxide) modifiedpoly(dimelhyl siloxane) complcxcd with lithium salts,Polymer, 32,2712-2715 (1991).

27. A. Berg, G.A. Niklasson, K. Brantcrvik, B. Hedbergand L.O. Nilsson, Dielectric Properties of Cemen:Mortar as a Function of Water Content, J. Appl. Phys.71,5897-5903(1991).

28. K. Brantcrvik and G.A. Niklasson, Circuit Models forCement Based Materials Obtained From ImpedanceSpectroscopy, Cement Concr. Res. 21,496-508 (1991).

29. W. Estrada, A.M. Andersson, CG. Granqvist, A.Gorenstein and F. Decker, Infrared ReflectanceSpectroscopy of Electrochromic NiO,Hy Films madeby Reactive dc Sputtering, J. Mater. Res. 6,1715-1719(1991).

30. B. Heed, B. Zhu, B.-E. Mellandcr and A. Lunden,Proton conductivity in fuel cells with solid sulphateelectrolytes, Solid State Ionics, 46,121-125 (1991).

31. J. Håkansson and G.A. Niklasson, Multifractal Analy-sis of Gas Evaporated Metal Particle Aggregates, Z.Phys. D20,317-319 (1991).

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31 S.-J. Jiang, C.-B. Ye. M.S.R. Khan and CG. Granqvist,Evolution of Thermochromism During Oxidation ofEvaporated Vanadium Films, Appl. Opt. 30.847-851(1991).

33. M.S.R. Khan, K.A. Khan, W.Estrada and C.G.Granqvist, Electro-chromism and Thcrmochromism ofLixVO, Thin Films, J. Appl. Phys. 69,3231-3234(1991).

34. A. Lunden and B.-E. Mellander, On the electricalconductivity and other transport properties of moltensodium sulphate, Solid State Ionics, 48,127-129 (1991).

35. A. Lunden, B.-E. Mellander and B. Zhu, Mobility ofprotons and oxygen ions in cubic lithium sulphate,Acta Chem. Scand., 45,981-982 (1991).

36. G.A. Niklasson, K. Bramervik and L. Börjesson,Conductivity Relaxation in Silver Iodide-Silver BoravGlasses, J. Non-Cryst Solids 131-133,1096-1098(1991).

37. G.A. Niklason, A. Berg, K. Brantervik, B. Hedbergand L.O. Nilsson, Dielectric Properties of PorousCement Mortar Fractal Surface Effects, Solid StateComm. 79,93-96 (1991).

38. C.-A. Sjöblom and B.-E. Mellander, p-T phasediagrams of silver halides; A computer aided evalua-tion using thermodynamic data, High Pressure Re-search, 7,111-113 (1991).

39. J.A. Sotelo and G.A. Niklasson, Optical Properties ofFractal Clusters of Small Metallic Particles, Z. Phys. D.20,321-323(1991).

40. B.Stjema and CG. Granqvist, Optical Properties ofSnOj Thin Films: Theory and Experiment, Appl. Phys.Lett. 57,1989-1991 (1991).

41. A. Talledo, A.M. Andersson and CG. Granqvist,Structure and Optical Absorption of Liy V2O5 ThinFilms, J. Appl. Phys. 69,3261-3265 (1991).

42 C.N. Wiyayasekera and B.-E. Mellandtr, Crystaldefects in the sodium sulfate rich pan of the sodiumsulfate - lithium sulfate system; An ionic conductivitystudv. Radiation Effects and Defects in Solids 119,981-^86(1991).

43. C.N. Wijayasekera and B.-E. Mellander, Ionic conduc-tivity and phase transitions of the lithium sulfate -lithium phosphase system, Solid State Ionics 45,293-298(1991).

44. I. Albinsson, P. Jacobsson, B.-E. Mellandcr and J.R.Stevens, Ion association effects and ionic conduction inpolyalkalene modified dimeuiyyioxanes, Solid SlateIonics, 53-56,1044-1053 (1992).

45. 1. Albinsson, B.-E. Mellander and J.R. Stevens, Ionicconductivity in polypropylene glycol) complexed withlithium and sodium triflate, J. Chem. Phys. 96,681 -690(1992).

46. N.H. Andersen, P.W.S.K. B2rtdaranayke, M.A.Careem, M.A.K.L. Dissanayake, R. Kaber, A. Lunden,B.-E. Mellander, L. Nilsson, J.O. Thomas and C.N.Wijayasekera, Paddle-wheel versus percolationmechanism for cation transport in some sulphatephases, Solid Slate Ionics, 57,203-209 (1992).

47. M.Friesel, B.-E. Mcllander and J.Kubat, Phasetransitions in poly(cthylene oxide) and polystyrene athigh pressure, High Pressure Research 9.169-172(1992).

48. P. Jacobsson, I. Albinsson, B.-E. Mellander and JR.Stevens, Ion association effects and phase separation inpoly(propylcne-oxide) modified poly(dimethylsilo-xanc) complexed with triflate salts, Polymer 33,2778-2783 (1992).

49. T.MJ. Nilsson, G.A. Niklasson and CG. Granqvist, ASolar Reflecting Material for Radiative CoolingApplications: ZnS Pigmented Polyethylene, Proc. SPE1727,249-261 (1992); also in Solar Energy Mater.Solar Cells 28,175-193 (1992).

50. J.L. Tallon and B.-E. Mellandcr, Large enhancement inoxygen mobility in the superconductors RBa2Cu3O7with increasing rare-earth size, Science, 258,781-783(1992).

51. I. Albinsson and B.-E. Mellandcr, Electrical relaxationin polymer electrolytes, to be published in: Fast IonTransport in Solids, Ed. B. Scrosati (Kliiver AcademicPublishers, Dordrecht, 1993).

52. I. Albinsson, B.-E. Mellandcr and J.R. Stevens, Ionassociation effects and ionic conductivity in polymerelectrolytes, submitted to Solid State Ionics.

53. A.M. Andersson, C.G. Granqvist and Z.G. Ivanov,Superconducting Properties of Elcctrochemically Li+Intercalated YiBa2Cu3C»7-S Thin Films, Mater. Sci.Engr. B, to be published.

54. CG. Granqvist, Electrochromic Materials: MetalOxide Nanocomposiles with Variable Optical Proper-lies, Mater. Sci. Engr. B. to be published.

55. CG. Granqvist, Electrochromic Materials: Microstruc-turc, Electronic Bands, and Optical Properties, Appl.Phys.

56. B.-E. Mellander and B. Zhu, High temperature proto-nic conduction in phosphate based salts, submitted toSolid State Ionics.



57. G.A. Niklasson and T.MJ. Nilsson, RelaxationProcesses in Insulator Thin Films, J. Phys. Condcns.Matter, to be published.

58. G A. Niklasson, Adsorption on Fractal Structures:Application to Cement Materials, Cem. Concr. Res., tobe published.

59. C.-A. Sjöblom and B.-E. Mellander, Computerevaluation of p-T phase diagrams, submitted to HighPressure Research.

60. Å.Wendsjö, J. Lindgren and B.-E. Mellander, Thephase diagram for the system PrXCFsSOjh - PEO,Solid State Ionics, in press.

61. S.-Y. Zheng, A.M. Andersson, B. Stjema and CG.Granqvist, Optical Properties of Sputter-depositedCerium Oxyfluoride Thin Films, Appl. Opt., to bepublished.

62. B. Zhu and B.-E. Mellander, Novel proton conductingceramics for solid state fuel cells, submitted to J.Electrochem. Soc.

63. B. Zhu and B.-E. Mellandcr, Proton conductingsulphate ceramics, submitted to Solid State Ionics.

64. B. Zhu, B.-E. Mellander and J. Chen, Cubic M3PO4(M=Li, Na, K) polymorphs with high ionic conductiv-ity, submitted to Mat. Res. Bull.

D. Conference Papers1. K. Brantervik and G.A. Niklasson, Dielectric Proper-

ties of Zinc Oxide Based Varistors, Proc. 3rd Intern.Conf. on Conduction and Breakdown in Solid Dielec-trics, Trondheim, Norway, (IEEE, New York, 1989>,pp. 309-312.

2. G.Mbise,G.B. Smith, G.A. Niklasson and C.G.Granqvist, Angular Selective Window Coatings:Theory and Experiment, Proc. SPIE 1149,179-199(1989).

3. G.A. Niklasson and T.S. Eriksson, Radiative Coolingwith Pigmented Polyethylene Foils, Proc. SPIE 1016,89-99(1989).

4. A.M. Andersson, W. Estrada, CG. Granqvist, A.Gorenstein and F. Decker, Characterization ofElectrochromic de-Sputtered Nickcl-oxidc-bascdFilms, Proc. SPIE 1272,96-110 (1990).

5. A.M. Andersson, C.G. Granqvist and J.R. Stevens, AnElectrochvomic LixWO3/poIymer laminatc/LiyV^OsDevice, in Large-area Chromogenics: Materials andDevices for Transmitlancc Control, eds. CM. Lampertand CG. Granqvist (SPIE Opt. Engr. Press, Belling-ham, 1990), pp. 471 -481.

6. A.M. Andersson, A. Talledo, CG. Granqvist and J.R.Stevens, Electrochromic Coatings and Devices forLarge-area Transmitlance Control, in Proc. Symp.Electrochi-omic Matenals, eds. M.K. Carpenter andD.A. Corrigan, Proc. Vol. 90-2 (The ElectrochemicalSoc., Pennington, 1090), pp. 261-273.

7. W. Estrada, A.M. Andersson, F. Decker and A.Gorenstein, "In Situ" Optical Mechanical and Electro-chemical Characterization of Electrochromic HyNiOx

Films, in Proc. Symp. Elcctrochromic Materials, eds.M.K. Carpenter and D.A. Corrigan, Proc. Vol. 90-2(The Electrochemical Soc., Pennington, 1990), pp. 54-69.

8. S.-J. Jiang, C.-B. Ye, M.S.R. Khan and CG. Granqvist,Structural and Compositional Evolution duringOxidation of Vanadium Coatings, Proc. SPIE 1272,185-196(1990).

9. M. Kakihana, S. Schantz, B.-E. Mellander and L.M.Torell, Temperature dependence of the charge carriergeneration in polymer electrolytes; Raman and conduc-tivity studicsof poly(propylcne oxidc)-LiClO4, in:Proceedings of the second international symposium onpolymer electrolytes, ed. B. Scrosati, (Elsevicr,London, 1990).

10. K.A. Khan and CG. Granqvist, Thcrmochromism ofSputter Deposited Vanadium Oxyfluoridc Coatings, inLarge-area Chromogenics: Materials and Devices forTransmittance Control, eds. CM. Lampert and C.G.Granqvist (SPIE Opt. Engr. Press, Bcllingham, 1990),pp. 160-167.

11. G.A. Niklasson, Degradation of Solar CollectorCoalings: Model Calculations for Nickel PigmentedAluminium Oxide, Proc. SPIE 1272,250-264 (1990).

12. G.A. Niklasson, Theoretical Model for the Durabilityof Solar Selective Absorber Coatings at ElevatedTemperatures, in Energy and the Environment Into the1990s, (edited by A.A.M. Sayigh, Pcrgamon, Oxford,1990), pp. 1372-1376.

13. T.M.J. Nilsson and G.A. Niklasson, Comparison ofDielectric and Optical Properties of Nickel OxideBased Electrochromic Coalings, Proc. SPIE 1272,129-138(1990).

14. S. Passcrini, B. Scrosali, A. Gorcnstcin, A.-M.Andersson and CG. Granqvist, Solid State Electro-chromic Devices, in Proc. Symp. ElcctrochromicMaterials, cds. M.K. Carpenter and D. A. Corrigan,Proc. Vol. 90-2 (The Electrochemical Soc., Penning-ton, 1990), pp. 237-245.

15. B. Sijcrna and C.G. Granqvist, Optical Properties ofSnOx Thin Films: Experimental Data and TheoreticalModel, Proc. SPIE 1272,12-25 (1990).

42 THE CENTRE FOR


16. J.S.E.M. Svensson and CG. Granqvist, SputterDeposited Nickcl-oxidc-bascd Electrochromic Coat-ings, in Large-area Chromogenics: Materials andDevices for Transmittance Control, eds. CM. Lampertand CG. Granqvist (SPIE Opt. Engr. Press, Belling-ham, 1990), pp. 285-297.

17. C.N. Wijayasekera, M.A.K.L. Dissanayake, M.A.Careem and B.-E. Mellander, On the irreversible phasetransition in lithium phosphate; thermal analysis, X-raydiffraction and ionic conductivity measurements,Proceedings of the Sri Lanka Association for theAdvancement of Science, 46 (1), 123-124 (1990).

18. W. Wixwat, J.R. Stevens, A.M. Andersson and C.G.Granqvist, An Adhesive Polymer Electrolyte forElcctrochromic Smart Windows: Optical and ElectricalProperties of PMMA-PPG-LiCIO4, in Second Interna-tional Symposium on Polymer Electrolytes, edited byB. Scrosati (Elsevicr Appl. Sci., London. 1990, pp.461465.

19. Z.Q. Yin, B. Stjema and CG. Granqvist, AntireflcctionCoatings of Sputter-deposited SnOxFy and SnNxFy,Proc. SPE 1536,149-157(1991).

20. T.MJ. Nilsson and G.A. Niklasson, Optimization ofOptical Properties of Pigmented Foils for RadiativeCooling Applications: Model Calculations, Proc. SPIE1536,169-182(1991).

21. A. Azens, A. Talledo, A.M. Andersson, G.A.Niklasson, B. Stjcrna, CG. Granqvist and JR. Stevens,W oxideftolymer laminate/ V oxide ElcctrochromicSmart Windows: Recent Advances, Proc. SPIE 1728,103-117(1992).

22. R. Gatt, G.A. Niklasson and CG. Granqvist, Degrada-tion Modes of Cermet Based Selectively Solar Absorb-ing Coatings, Proc. SPIE I727,87-101 (1992).

23. J.C. Gustafsson, O. Inganas and A.M. Andersson,Conductive Polymers as Elcctrochromic Materials inSolid State Elcctrochromic Devices, Proc. SPIE 1728,to be published (1992).

24. A. Lunden, B.-E. Mcllandcr and B. Zhu, Protonconductivity in oxyacid salts at high temperature, inMaterials for High Temperature Fuel Cells, ed. B.Bergman,(Mcdiatcknik KTH, Stockholm, 1992), p. 131.

25. A. Talledo, A.M. Andersson and CG. Granqvist,Structure and Optical Absorption of Liy V2O5 ThinFilms, in Surface Science: Lectures on Basic Conceptsand Applications, Springer Proc. Phys., eds. F.A.Ponce and M. Cardona (Springer, Berlin, Heidelberg,1992), Vol. 62, pp. 315-316.

26. S.-Y. Zheng, A.M. Andersson, B. Stjema and CG.Granqvist, Cerium Oxide and Oxyfluoridc Thin Filmsfor Energy efficient Windows, in Renewable Energy:Technology and the Environment, edited by A.A.M.Sayigh (Pergamon, Oxford, 1992), pp. 164-172.

27. S.-Y. Zheng, A.M. Andersson, B. Stjema and C.G.Granqvist, Optical and Electrochemical Properties ofCerium Oxyfluoride Thin Films, in Technical Digest ofof 1992, Int. Conf. on Lasers and Optoelectronics(ICLOE'92),p.48.

28. B. Zhu, J. Chen and B.-E. Mcllandcr, Proton conduc-tion in phosphates, in Materials for High TemperatureFuel Cells, ed. B. Bergman, (Mediateknik KTH,Stockholm, 1992) p. 159.

29. G.A. Niklasson and B. Ncttclblad, Dielectric Propertiesof Porous Materials, IEE Conf. Publ., 363,450453(1993).

30. B. Stjema and CG. Granqvist, Optical and ElectricalProperties of Doped RF Sputtered SnG\ Films, Proc.SPIE 1727,178-193(1993).


Materials chemistryInorganic Chemistry 46Reaction Dynamics 58Chemical Analysis - Swedish National



Inorganic Chemistry, CTH/GU

Research summaryMuch of the basic research at the department isdirectly connected to materials science. There is along tradition on solid state chemistry, especiallywith respect to synthetic inorganic chemistry, struc-turalchemistrybasedondiffractionand spectroscopicmethods, and relations between structure and prop-erties. Other important fields of basic research areelectrochemistry and heterogeneous kinetics. Thementioned research fields are supported actively byexpertise within quantum mechanical calculations.

The applications within material research de-scribed below are strongly connected to and based onthe basic research areas. Electrochemical applica-tions are dissolution of metallic materials, mineralflotation and material aspects of battery technology.

Areas of application connected to solid statechemistry are structure-property relationships inceramics and in high Tc-superconducting materials.Another field is growth of large crystals and inves-tigation of their properties.

Heterogeneous chemistry is applied within com-bustion relatedresearch,i.e.characteristicsofbiornassand coal fuels, of ash components and of FBCadditions. Main fields are atmospheric and hightemperature corrosion involving important materi-als such as ceramics, metals, natural stones andpaper.

Surface reactions are studied in situ by tempera-ture controlled (180-1800 K) surface X-ray diffrac-tion and FT-IRAS spectroscopy. A specific field ofcompetence is structural research based on synchro-tron radiation research.

AddressDepartment of Inorganic Chemistry, CTH/GUChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone +46 317722850Fax 446 31 167194

46

StaffSenior MembersLindqvist, OliverAlbertsson, JörgenAhlberg, ElisabetJagner, SusanJohansson, GunnarLanger, VratislavLjungström, EvertSjölin, LennartStomberg, RolfBerggren, JanBerghult, BoBörtin, OlleEriksson, StenGobom, SylviaHåkansson, MikaelIdrestedt, IngvarPanas, ItaiStrömberg, DanSvensson, Göran

Graduate StudentsAlenljung, RogerAndersson, HelgeBerastegui, PedroChen, JiaxinElfströrn-Broo, AnnElfving, PernillaEriksson, HenrikHallqvist, MattiasHeim, MaikenJohansson, AnnaJäglid, UlfKassman, HåkanKarlsson, RuneLanger, Särka

Lindstedt, AnjaLopes, CesarMattisson, TobiasMiettinen, HeijeÖländers, BirgittaOlsson, Lise-Lotte

prefekt, professorprofessordocentdocentdocentdocentdocentdocentdocenttekn.dr.tekn.dr.tekn.dr.fildr.fil.dr.tekn.dr.tekn.dr.fil.dr.fil.dr.tekn.dr.

fil.kand.fil.kand.filkand.fil.kand.fil.kand.fil.kand.civ.ing.

fil.kand.fil.kand.fil.kand.fil.kand.civ.ing.civ.ing.filkand.civ.ing.fil.kand.fil.kand.fil.kand.civ.ing.

fil.kand.

THE CENTRE FOR

INORGANIC CHEMISTRY. CTH/GU

Potter, Douglas fil.kand.Shirazi, Ahmad Resa fil.kand.Snis, Anders fil.kand.Steenari, Britt-Marie civ.ing.Strandberg, Helena fil.kand.Ström, Carin fil.kand.Svensson, Jan-Erik fil.kand.Tsai,Li-Chu filkand.Tullin, Claes civ.ing.Wettström, Catarina civ.ing.Xiao, Zifan fil.kand.Åhman, Johan civ.ing.

Technical StaffAbul-Milh, Miroslawa Ph.D.Forsberg, Roger techn.Karlsson, Kajsa ing.Kovacs, Janos ing.Lagerqvist, Lars techn.Lundqvist, Eva ing.Nilsson, Ove civ.ing.Olsson, Solveig ing.Puromäki, Käthe Ph.D.Selander, Sören ing.Väanänen, Esa techn.Wang, Jian civ.ing.

SecretaryBergström, Britt

Major Instrumentation• Single crystal diffractometers, Syntex, 1975,

Contact person: Janos Kovacs, tel. 772 2855• Single crystal diffractometer, Rigaku, 1989,

Contact person: Mikael Håkansson/JanosKovacs, tel. 772 2856/2855

• Single crystal diffractometer, Enraff-Nonius,1993, Contact person: Göran Svensson, tel.7722882

• Single crystal growth apparatus, Crystalox,1993., Contact person: Göran Svensson, tel.7722882

• Powder diffractometers, Siemens D5000,1992, Contact person: Vratislav Langer/JanosKovacs, tel. 772 2877/2855

• Medium frequency induction heater, Stanelco,1993, Contact person: Göran Svensson, tel.7722882

DTA balance gravimeter, TA-1, Mettler, 1982,Contact person: Maiken Heim, tel. 772 2888FTIR- spectrometer, Perkin Elmer, 1800,1986, Contact person: Pernilla Elfving, tel.7722860Ion chromatograph, HPLC-system, 1987,Contact person: Pernilla Elfving, tel. 772 2860Atomic absorption spectrometer, Philips, 1987,Contact person: Käthe Puromäki, tel. 772 2887Electrochemical instrumentation: PotentiostatsPAR 173/276, PAR 273A, Frequency responseana'yser Solatron 1255, Lock-in-amplifierPAR 5210. The instrumentation can be usedfor analyses, corrosion studies as well as forfundamental electrochemical research. Con-tact person: Elisabet Ahlberg, tel. 772 2879.Low Temperature Ashing, LFE Corp Model302,1989. Contact person: Ahmad ResaShirazi.

Major Fields of ResearchA: Materials Research in Electrochemistry,

participants: Elisabet Ahlberg, Bo Berghult,Ann Elfström-Broo, Ove Nilssoncollaborators: ABB atom, Sydkraft AB.

B: Reactivity of Ceramic Materials,participants: Jiaxin Chen, Maiken Heim,Oliver Lindqvist, Robert Pompe collabora-tors: Volvo Flygmotor AB, Swedish CeramicsInstitute.

C: Crystal Growth and Crystal Properties,participants: Jörgen Albertsson, GöranSvensson, Johan Åhmancollaborators: MAX laboratory, Lund

D: High-Tc Superconducting Oxides.participants: Pedro Berastegui, Sten Eriksson,Gunnar Johansson, Carin Strömcollaborators: Department of Physics CTH/GU

E: Atmospheric Corrosion Research.participants: Pernilla Elfving, Anna Johansson,Gunnar Johansson, Oliver Lindqvist, HelenaStrandberg, Jan-Erik Svenssoncollaborators: Volvo AB, National Board ofAntiquities, STFI.


INORGANIC CHEMISTRY, CTH/GU

F: Combustion related Materials Research,participants: Oliver Lindqvist, VratislavLanger, Käthe Puromäki, Ahmad ResiSchirazi, Britt-Marie Steenari.collaborators: ABB Carbon, Department ofEnergy Conversion CTH, Celsius.

Research Projects

A: Materials Research InElectrochemistry

Al: Electrode kineticsDuring the last ten years the ELECTRO-CHEMISTRY GROUP at the department of Inor-ganic chemistry GU/CTH has worked with differentmetal and mineral dissolution reactions. Mainlyelectrochemical techniques have been used and themechanistic interpretations performed are based ontraditional evaluation of kinetic parameters like theTafel slope and the reaction order dependence fromsteady state measurements. In recent years we havesuccessfully used Impedance Spectroscopy in con-junction with polarization measurements in the in-terpretation of the kinetics of metal dissolution reac-tions as well as adsorption/desorption phenomena.The metal systems most carefully studied by thegroup are iion in acidic aqueous solutions and inacetonitrile/water medium, lead in acidic electrolyteproviding both active dissolution and partialpassivation by the formation of small amounts oflead sulfate and zinc in slightly acidic aqueoussolutions. In many practical applications metalsforming passivating oxide layers are used.

The electrochemistry of sulphide minerals hasbeen studied with the emphasis on the flotation andleaching processes. Most sulphide minerals are goodelectric conductors or semiconductors andelectrochemical models have successfully been usedfor the interpretation of the~e processes. However,for low conducting minerals the electron transferstaking place should be regarded as localised andbecause of the low mobility in the solid these reac-tionscan not be studied by traditional electrochemicalmethods.

Further studies will focus on the temperaturedependence and the double layer effects of metaldissolution reactions and on the influence of

passivating oxide layers on the electrochemical re-sponse.References: 1,2,3,29,30,31,32,33,34,53,54 76,77,78,96,103,104,105.

A2: Materials in Battery TechnologyThe Department of Inorganic Chemistry has a tradi-tion in battery R&D, especially in the lead acidbattery. The increase of material utilisation of theporous PbO2 electrode without sacrificing the cyclelife is a crucial problem. The research has beendirected towards thin electrodes and processes tooxidise lead foils to PrXVelectrodes.

The need for a better environment involves alsothe development and use of Electric Vehicles. Onetask we have undertaken in that area is the develop-ment of a bipolar, high power density battery inwhich the use of thin electrodes and minimum ofacid and inactive material is the main idea. Theproject also involves new methods to make theseelectrodes.

The future activities will involve also red-oxbatteries. The use of DS A electrodes or graphite willgive such batteries a substantially increased lifecompared to any other battery.

Further, the research group will be enlarged todeal with material problems as well as electro-chemical performance of Solid Oxide Fuel Cells.The studies will centre around high temperaturecorrosion of ceramics and metals, ion conductivityof ceramic materials and electrochemical activitiesof perovskite. The applications we are aiming at areflue gas abatement and power generation.References: 35,112.

B: Reactivity of Ceramic Materials.

Bl: Oxidation/Corrosion ofadvanced ceramics composites and fibres

Advanced ceramic fiber composites (CMC) areconsidered for use in the burning chamber of jetengines, rocket engines and other applications re-lated to more efficient energy conversion. Theseapplications involve operation temperatures up to1600 °C.

The objective of the project is to investigate theresistance to oxidation/corrosion of selected fibersand ceramic matrix composites in oxidative and/or

48 THE CENTRE FOR


corrosive environment. The effect of constituentspresent in exhaust gases such as H2O, SO2, hydro-carbons as well as salts will be examined to identifythe mechanisms and kinetics governing the nature ofthe corrosive attack.

Two types of composites will be studied:a) dense (HIP - Hot Isostatic Pressed) specimensbased on Si3N4 matrix/SiC (C) fibres and SiC ma-trix/SiC(C) fibres exposed short time to high tem-perature andb) porous composites (oxide and/or non-oxide ma-trix/oxidic fibres) and their behaviour on long termexposure.

Experimental techniques which are employedinclude thermogravimetry and heat treatment inspecially equipped furnaces. The corrosion productsare identified using a wide spectra of analyticaltechniques such as XRD, XPS, AES, IR andRAMAN. These are combined with micro structuralstudies with TEM/SEM/EDS and spectro-ellipsometry. References: 49,67,71,72,93.

B2: High temperature oxidation & corrosionof structural ceramics

Ceramic materialsarepromisingcandidatesfor manyhigh temperature applications. The evaluation oftheir oxidation and corrosion behaviour becomesparticularly important when the consequence of thematerial failure is catastrophic. In cooperation withVolvo Flygmotor AB and Department of Physics atChalmers as well as Shanghai Ceramic Institute, wehave tested the oxidation- and corrosion resistanceof some advanced ceramics, such as silicon carbidecomposite and hot isostatic pressed silicon nitride, insevere corrosion environments at high temperature.To study the oxidation and corrosion mechanism ofthese materials, we have applied various surfaceanalytical techniques such as glancing angle X-raydiffraction, electron microscopy, infraredspectroscopy, X-ray photoelectron spectroscopy,Auger electron spectroscopy, and spectroscopicellipsometry. We have observed that on oxidation ofcarbide and nitride, much more crystalline structuresof the oxide scales are formed than that on singlecrystal silicon, even though the final oxidation prod-ucts on the materials have essentially the samechemical compositions. Many peculiar oxidationbehaviour of carbide and nitride could be readilyunderstood in the light of this observation, becausethe oxidation process is an O2 diffusion controlled

process which is sensitive to the structure of thediffusion medium. For the corrosion of the ceramics,we have concluded that gaseous corrosion in thesimulated combustion environment which containsNOX, SO2/SO3, H2O, CO2, O2 etc. will be essen-tially the same as oxidation in O2 or in air. For the hotcorrosion where a constant stream of NaCl vapour isintroduced into a gaseous corrosion environment,however, the material surfaces undergo severe cor-rosion damage due to the formation of a largeamount of low viscosity silicate. We have pointedout that the corrosion may be caused by the reactionbetween materials and NaOH(g) which is formed athigh temperature. Our future work will be to exam-ine the O2 diffusivity in various sodium-containingsilica materials so that we can predict the actual hotcorrosion process. References: 38,55, 56.

C. Crystal Growthand Crystal Properties.C l : Structure-property relations

of inorganic materialsCrystal growth is of great importance in materialresearch. A crystal laboratory was started in Lund in1989 but will be moved to Chalmers University ofTechnology in Göteborg in 1993. The main interestis in crystal growth and characterisation of non-linear optical materials. The research is focused onexperimental conditions that effects the crystal qual-ity as e.g. shape and material of crucible, thermalconditions, growth speed, impurities and dopanddistribution. The crystals are characterised by dif-fraction methods, electron microscopy, etching, lu-minescence and others.

We are involved in several projects, but our maininterest is non-linear optical materials. Below fol-lows a list of projects.1. Growth of germanium for a neutron detector.

(Dr. Roland Tellgren, Studsvik).2. Growth and characterisation of Co-doped

LiGasOg for optical storage of data. (Dr.Stefan Kröll, Atomic Physics in Lund).

3. Growth of CsI/CsBr for calorimetric measure-ments in nuclear- and particle physics. This is acollaboration between several laboratories inEuiope called "Crystal Clear Collaboration"organised from CERN. (Dr. Leif Jönsson,Particle Physics in Lund).


INORGANIC CHEMISTRY, ClH/GU

4. Growth and characterisation of non-linearmaterials such as LiNbC^, LiTaO3, KT1OPO4and KTiOAsO4. (Dr. Fredrik Laurell, TheInstitute for Optical Research in Stockholmand Dr. Rindert Bolt, Holland).

5. Other projects are studies of compounds suchas CuCl, LaF3, HCN and DCN.

C2: Structure-property relationsfor dielectric materials.

The microscopic origin of various dielectric andmagnetic phenomena are studied. A direct relation-ship, on the atomic level, between external action(changes in temperature, electric field, hydrostaticpressure etc.) and polarisation has been developedfor several pyroelectric and ferroelectric crystals.Much information is also obtained from phasechanges when crystal properties change and newproperties appear while others disappear. Our ulti-mate goal is to calculate tensor components describ-ing electric, opdc and mechanical properties of ma-terials. A thorough knowledge about how to growand dope the materials is of importance for anycharacterisation and future application. Materials ofpresent interest in our investigations are the alphaand gamma phases of UIO3 related alkali metaliodates and iodic acid, ZnO and other pyroelectricswith wurtzite structure and SrAlFs and related struc-tural families of double fluorides. Among the lattercompounds most work has been with the ferroelectricsPb5M3F19,M=Cr,AlorFe.

D: Synthesis and structurepropertyrelations In hlgh-Tc superconductingoxides.Our research on high-Tc cuprate superconductorswas initiated in early spring 1987. We work withsynthesis and characterise the materials by use ofvarious diffraction techniques. Single crystals aswell as polycrystalline materials are studied by x-raydiffraction, the latter also by neutron powder diffrac-tion. Spectroscopic methods (NMR, Raman, X AFS,XPS, Mössbauer) as well as wet chemical andgravimetric techniques also play an important role inour research. An extensive network of collaboratorshas been developed on a national as well as aninternational basis and we are today highly competi-tive.

Polycrystalline materials are prepared by solidstate sintering, vacuum line and high pressure meth-ods, polymerised complex routes, reaction in closedsystems and by use of precursor techniques. Moreo-ver, we also work with single crystal growth and thinfilm fabrication. Due to the broad spectrum of pre-parative methods used we are able to synthesise alarge number of high-Tc materials such as Y-123, Y-247, Y-124, Tl-2201, Tl-2212, Tl-1201, Tl-1212and Bi-2201 just to mention a few.

Aiming at an increased understanding for struc-ture- property relationships in these and other cupratesa vast number of doped materials have been preparedand structurally characterised. In this context we usediffuse neutron scattering and magnetic scattering toobtain information concerning atomic disorder andmagnetic order, respectively. Our work on the socalled ortho II phase in the RE-123 system is oneexample of the problem of atomic disorder. Moreo-ver, a systematic search for new high-Tc supercon-ductors among antiferromagnetic oxides with pro-nounced 2D character has been started. In for in-stance Y-123 and in the thallium cuprates there is astrong competition between superconducting andantiferromagnetic behaviour. One state or the othercan be stabilised by appropriate doping, a techniquethat we have much experience in.References: 7,8,9,10,11,18,19,20,21,22,23,28,42,46,47,48,64,65,70,83,84,85,86,94,95,99,100,101,102,106,107,108,109,110.

E: Atmospheric Corrosion Research.The atmospheric corrosion chemistry group studiesreactions that occur when metallic and non-metallicmaterials are exposed to humid atmospheres con-taining traces of reactive air pollutants (e.g. NO2(g),O3(g), SO2(g), Cl2(g), H2S(g) and NaCl(s)). Inparticular we study the combination effects thatoccur when two or more corrosive micro-compo-nents interact on the surface. For example we haveshown that NO2, which by itself is rather unreactivetowards most materials, may accelerate corrosionappreciably in combination with SO2. We havefound evidence for such a synergistic effect of SO2

and NO2 with materials as diverse as marble, carbonsteel, copper, zinc and gold-coated brass (Johansson1984, Eriksson and Johansson 1990, SvedungJohansson and Vannerberg 1983, Johansson, Mangioand Lindqvist 1988, Svensson and Johansson 1989).

50 THE CENTRE FOR


Similar effects occur when ozone is combined withSO2 (Mangio and Johansson 1989, Eriksson andJohansson 1992, Svensson and Johansson 1993). Itis well known that small amounts of NaCl acceleratethe atmospheric corrosion of many metals. This isprimarily caused by the increasing conductivity ofthe surface electrolyte and by the enhancement of theanodic reaction by chloride. However, the corrosiveeffect of combinations of NaCl with corrosive tracegases on metals and calcareous stones has not beenthoroughly studied in the past. Our study on zinc(Svensson and Johansson 1992) is the first system-atic work dealing with the complex interactionsbetween chloride and corrosive trace gases at sub-ppm concentrations on a corroding surface.

MethodologyThe most important experimental techniques in-clude the following:

1) Real-time studies of the kinetics of depositionand formation of trace gases on materials.

The consumption of SO2, O3 and NO2 and theformation of NO and HNO2 on e.g. metal samples isstudied in a time-resolved manner. The sample isexposed in a flow-reactor and the output gas isanalysed by the different gas analysers that have fastresponse and high sensitivity (about 1 ppb). Thesensitivity of the analysers allows us to work atambient concentrations of SO2, NO2 and O3 (20 -1 OOppb). The concentration changes that we registerare caused by reactions on the surface of the sample.This experimental set-up is best suited for exposuresof short duration (< one week), for example studyingthe initiation of atmospheric corrosion. We havealso developed a fixed-bed reactor technique toinvestigate the kinetics of the reactions between thedifferent corrosion products and gaseous specieslike SO2, NO2 and O3 without the influence of themetal. The gas analysis is supplemented by ion

SO2 analyser 1 NO-NOX/O3

analyser Excess air

Pressurizedpurified air

Reactor0 s 28 mm

I Sample

Mass flowregulators

Humidifier

03-generator

Permeationtubes SO 2 /NOj

Thermostated water tank

Experimental arrangement for time-resolved study of the deposition andformation of SO2. NO, NO2 and 0 3 on solids.

MATERIALS SCIENCE, »993 51


chromatography after the exposure. This type ofstudy allows us to close the mass balance for thecorrosive substances, to determine reactionstoichiometries ai d to study the kinetics of thereactions.2) Corrosion rate measurementsIn order to link the kinetic studies of the interactionof corrosive trace substances on the zinc surface tothe corrosion rate of the metal we will carry out longterm exposures under controlled conditions. Theexperimental set-up was developed at our labora-tory. The corrosion rate is determined from the metalloss after exposure. In addition, mass gain measure-ments are performed during exposure. The corrosionproducts formed are studied by XRD, and ion chro-matography . In addition the corroded samples willbe analysed by SEM-EDX and XPS.

3) FT-IRAS and-DRIFT measurements; Investi-gations of the formation of reactive intermedi-ates on the surface.

A specular reflectance cell is used to study corrosionproducts and adsorbed species formed on metalsurfaces. We have access to a high performanceFTIR-instrument with MCT detector (Perkin Elmer1800). Using this equipment, adsorption layers lessthan a monolayer thick may be studied. The gradualbuild-up of corrosion products and adsorbates dur-ing the initial stages of corrosion is studied. Inaddition we use in-situ diffuse reflectancespectroscopy to study adsorbates and compoundformation on powdered substances, i.e. solid corro-sion products.References: 5,6,15,16,25,26,27,37,40,41,43,52,57,58,63,68,69,81,82,92.

BaF2 windowsTemperature controlled brast plate

Sample

i t Igas gasoutlet inlet

gasoutlet

Schematic view of the in-situ Fourier transformspecular reflectance cell.

F: Combustion related MaterialsResearch.

F l : Coal Research

The sulphur in coal is present as sulphides or sul-phates, as organic compounds and as elementarysulphur. They are all sources for SO2 in flue gas.Especially in pre-cleaning methods of coal it isnecessary to know the quantity and also the qualityof these compounds. By using an Electron ProbeMicro Analyser and Automatic Image Analysis, e.g.the content of pyrite, marcasite and pyrhotite inpyritic sulphur mineral has been determined, whichis not possible by using standard methods of analy-sis.

The time of analysis is proportional to the amountof particles which have to be counted for a pre-setaccuracy. However, the analysis area can be reducedby applying Low Temperature Ashing (LTA; LFECorp. model 302) before the analysis. In this processa radio frequency generator ionises oxygen at ,owpartial pressure and oxygen reacts with the coalsample. Thus the mineral matter will appear morereadily available for the analysis. It has been possibleto lower the ashing temperature to 70° C by substi-tution of the oxygen for a mixture of oxygen andhelium (Very low temperature Ashing, VLTA).Thus the oxidation of the sulphides is avoided.

F2: Ash characterisation.

Diffraction studies of ashes from different combus-tion processes are performed on this instrument. Thequalitativeanalysisisdoneinteractivelyon the screenwith JCPDS databasis on-line. Quantitative analysisof Ca-compounds has been developed.

Department of Inorganic Chemistry GU/CTHwas one year ago equipped with a new powderdiffractometer, Siemens D5000. The specific fea-tures of the diffractometer are: high effect X-raygenerator and tube, scintillation and position sensi-tive detector (PSD), high and low temperature cellsand a thin film attachment.

The high temperature cell operates from roomtemperature up to 1600° C in vacuum and up to1200° C in different atmospheres (Pt - heat element).In connection with position sensitive detector, it ispossible to follow quick changes (reactions in situunder controlled temperature and atmospheric pres-sure ) or phase changes (reversible or irreversible)with temperature, scanning with PSD 160° diffrac-

52 THE CENTRE FOR

tion angle within few minutes. The low temperaturecell can be used for temperatures from -190 to +300°C in a similar manner.

The thin film attachment is based on the fact thatincident beam is touching the surface under verysmall angle, causing only surface material to diffract.As diffracted radiation is divergent in this arrange-ment, long Soller slits and a flat secondarymonochromator are used to select diffracted X-raysto scanning scintillation detector. This results inmagnification of the signal from the surface and theinfluence of the substrate can be minimalized. Ofcourse, the thin film configuration can be used incombination with both high and low temperaturecells.References: 13,17,50,61,62,87,88,89,90,91,97,111.

PublicationsPh.D. Dissertations (1989-)Andersson, Y., Thesis: Gas-Phase Kinetic Studies of

Relevance to Atmospheric Chemistry (1989).

Carlström, E., Thesis: Defect Minimisation in SiliconCarbide, Silicon Nitride and Alumina Ceramics (1989)1-87.

Cooper, D., Thesis: Some Aspects of NOx Control inFluidized Bed Combustion (1989).

Eriksson, S., Thesis: On the structure and Properties ofsome Doped Y-I23 Cuprate superconductors andRelated Non-Superconducting Materials (1989) 1-107.

Friel, M.( Thesis: The Polarisation of Iron in AcidicAcctonitrile-Watcr Solution (1989).

Bcrghult, B., Thesis: Fundamental ElectrochemicalAspects of the Lead Electrode in Connection with theLead-Acid Battery (1990).

Hclgcsson, G., Thesis: Dependence of the coordinationnumber of silvcr(I) in crystalline halogcnoargcntatcs(I)on the nature of the cation (1990).

Strömberg, D., Thesis: Some mercury Compounds Studiedby Relativistic Quantum Chemical Methods (!990).

Tcgehall, P-E., Thesis: The Chemistry of Zinc Phosphalingof Steel (1990).


Ghardashkhani, S., Thesis: The Chemistry Behind theSulfur Dioxide Removal by Calcium Oxide in Fluid-ized Bed Coal Combustion (1991).

Mangio, R., Thesis: The Influence of Various Air Pollut-ants on the Sulfation of Calcareous Building Materials(1991) 1-55.

Munthe, J., Thesis: The Redox Cycling of Mercury in theAtmosphere (1991).

Sjöberg, J., Thesis: On the Preparation and Structure of O'-Sialonsn(1991).

Eriksson, P., Thesis: Effects of SOz and NO2 on melalsurfaces: Atmospheric corrosion of copper and surfacereactions on gold (1992).

Hall, B., Thesis: An Experimental Study of MercuryReactions in Combustion Flue Gases (1992).

Wängberg, I., Thesis: An Experimental Study of someNitrate Radical Reactions of Importance to Tropo-spheric Chemistry (1993).

Licentiate DissertationsElfstrom Broo, A., Electrochemical Studies on the Galena/

Xanthate System, Relationship to Flotation, ISSN0283-8575, Report OOK 90:03,1-27.

Hall, P., Reactions of Mercury with Flue Gas Components,ISSN 0283-8575, Report OOK 90:06.

Schagcr, P., The Behaviour of Mercury in Flue Gases,ISSN 0283-8575, Report OOK 90:07.

Tullin, C , Sulphur Capture in Pressurised Fluidised BedCombustion, ISSN 0283-8575, Report OOK 90:04.

Xiao, Z., Some Aspects of Mercury as a Pollutant in theEnvironment, ISSN 0283-8575, Report OOK 90:05,1-39.

Elfving, P., Atmospheric Corrosion on Silane TreatedStones, ISSN 0283-8575, Report OOK 91:04,1-57.

Linsten, M., Some Properties of HydrothermallyDealuminated Y-Zeolites, ISSN 0283-8575, ReportOOK 91:02.

Tsai, Li-Chu., Crystallographic Investigations of WildType Azurin and Some Azurin Mutants fromPscudomonas aeruginosa, ISSN 0283-8575, ReportOOK 92:02.



Diploma WorkPotter, O., Lustgasemission frän katalysaurbilar, ISSN

0283-8575, Report OOK 90:02.

Shambayati, P., Ammonia Adsorption on SyntheticZeolities, Projektarbete 10 p. (1990).

Kämsby, J., Läkning av guld ur pyritiska malmer. Enelcktrokemisk studie, Projektarbete 20 p. (1990).

Börjesson, S., Bildningen av lustgas från kvävedioxid,svaveldioxid och vattenånga, Projektarbete 20 p.(1990).

Hansson, I., Utvärdering av procedur för analys av fastaprover från fluidiserad bäddpanna. Projektarbete 10 p.(1989).

Reports and artides1. The Anodic Dissolution of Iron in Acidic Acetonitrile-

Watcr Solution. Ahlberg, E. and Friel, M.Electrochimica Acta 34 (1989) 187-196.

2. The Cathodic Polarization of Iron in AcidicAcetonitrile-Water Solutions. Ahlberg, E. and Fricl, VI.Electrochim. Acta 34 (1989) 771-780.

3. An ac Impedance Study of the ElectrochemicalBehaviour of Iron in Acidic Acetonitrile-WaterSolutions. Ahlberg, E. and Friel, M. ElcclrochimicaActa 34 (1989) 1523-1528.

4. Thesis: Defect Minimisation in Silicon Carbide,Silicon Nitride and Alumina Ceramics. Carlström, E.(1989) 1-87.

5. Kiselsyraesterbaserad stenkonscrvcring -Litteraturstudie, Elfving, P. and Lerjefors M. ISSN0283-8575, Report OOK 89:08.

6. Kiselsyraesterbaserad stenkonservcring -Laboratoriekarakiarisering. Elfving, P. and Lindqvist,O. ISSN 0283-8575, Report OOK 89:09.

7. Thesis: On the structure and Properties of some DopedY-I23 Cuprate superconductors and Related Non-Superconducting Materials. Eriksson, S. (1989) 1-107.

8. Oxygen Content and Structural Properties of some Ba-Cu Oxides, Eriksson, S.G., Johansson, L.-G.,Börjesson, L. and Kakihana, M. Physica CI62-164(1989)59-60.

9. Investigations on Oxygen Content and Ordering inYl(Ba,Sr)2(Cu,Co)3O7.d Superconductors by means ofWet Chemical Analysis, X-Ray- and Neutron-Diffrac-tion Techniques. Eriksson, S.G., Johansson, L.-G.,Börjesson, L. and Kakihana, M. Physica C162-164(1989)73-74.

10. Structural Studies of Doped Y-123 Superconductors; AWay to Investigate the Role of Charge Distribution.Eriksson, S.G., Johansson, L.-G., Ström, C, Börjesson,L, Kakihana, M. and Kall, M. Physica C162-164(1989).

11. Y1Ba2.ySryCu3.xFexO7-<i, ^ ^ ^and Tl-2212 Superconductors; A Neutron Diffractionand Raman Spectroscopic Study. Eriksson, S.G.,Johansson, L.-G., Ström, C, Börjesson, L., Kakihana,M. and Kail, M. Physica C162-164 (1989).

12. Thesis: The Polarisation of Iron in Acidic Acctonitrile-Water Solution. Friel, M. (1989).

13. Release of Sulfur Dioxide from Calcium Sulfate underReducing Conditions. Ghardashkhani, S., Ljungströmand Lindqvist, 0.10th Int. Conf. on Fluidized BedCombustion, San Francisco (1989) 611-615.

14. TGA Determination of the Sulphur Dioxide Absorp-tion Capacity of some Spanish Limestones.Ghardashkhani, S., Ljungström, E., Lindqvist, O. ISSN0283-8575, Report OOK 89:04.

15. A Case Study on the Deterioration of Stones: ThreeChurches on the Island of Gotland. Gwenacllc, R.Report Autumn GC03.

16. Determination of the Sulphur Dioxide AbsorptionCapacity of two Fractions of Ignabcrga and KöpingLimestones. Jiiglid, U.

17. Hydration as a means of improving the sorbentutilization in Pressurized Fluidized Bed Combustion.ISSN 0283-8575, report 89:07.

18. The Influence of Oxygen Variation on Raman Scatter-ing and X-Ray Diffraction from B a C i ^ j . Kakihana,M., Börjesson, L. and Eriksson, S.G. Physica C162-164(1989)1253-1254.

19. Raman Scattering and X-Ray Diffraction in Ni and ZnSubstituted YBa2Cu3O6fli. Kakihana, M., Börjesson,L. and Eriksson, S.G. Physica C162-164 (1989) 1251-1252.

20. Raman spectra, superconductivity and structure of Co-substituted YBa2Cu3O7.d. Kakihana, M., Börjesson,L., Eriksson, S.G., Svedlindh, P. and Norling, P. Phys.Rev. B40 (1989) 6787-6796.

21. Synthesis of highly pure YBa2Cu3O7.j Superconduc-tors using a Colloidal Processing Technique. Kakihana,M.f Böijcsson, L., Eriksson, S.G., Svedlindh, P. andNorling, P. Physica C162-164 (1989) 931-932.

22. Phonon Raman Scattering and Structure of Co Substi-tuted YBa2Cu3O6f(j. Kakihana, M., Börjesson, L.,Torell, L.M. and Eriksson, S.G. Physica C162-164(1989) 1245-1246.

23. Raman Scattering from Metal (Co, Ni and Zn)-Subsututcd YBa2Cu3O7.«j. Kakihana, M., Börjesson,L., Torell, L.M. and Eriksson, S.G. Physica C162-164(1989).

24. Raman scattering from Sm-Ba-Cu-0 high TC supercon-ductors. Kakihana, M., Börjesson, L., Torell, L., Zhiyi,L. and Eriksson, S.G. Physica C156 (1988) 420-426.

25. Uno studio sul detcrioramento dclla pictra: la fontanadelta Caltcdralc a Göteborg. Lindqvist, O., Mangio, R.,Olsson, L. and Rosvall, J. Citta inquinata i monumenti,Italia Nostra, cd. Montanari, A. and pctraroia, P.,Institute Poligrafico c zeeca Dcllo Stato, Librcria DclloStato, Roma (1989) 287-304.

54 THE CENTRE FOR


26. The Influence of Ozone on the Atmospheric Corrosionof Carrara Marble in Humid Atmospheres ContainingSufur Dioxide; Deposition Studies of SO2 on Marble.Mangio, R. and Johansson, L.-G. Proc. 1 lthScandinavian Corrosion Congress, Stavanger, F-45(1989) 1-6.

27. A Laboratory Study of the Atmospheric Corrosion ofZinc: Synergistic effects of Trace Amounts of SO2,NO2 and NaCl(s). Svensson, J.-E. and Johansson, L.-G. Proc. 1 lth Scandinavian Corrosion Congress,Stavanger, F-47 (1989) 1-7.

28. Study of the effect of the substitution of O by F, S andCI on the superconductivity of YlBa2Cu3O7^. Yi, L.,Persson, M. and Eriksson, S.G. Z. Phys. B-CondcnscdMatter 74 (1989) 423428.

29. Anodic Dissolution of Lead in Perchloric Acid Solu-tions. Correction for Changes in Active Surface DuringPotential Dynamic Sweeps. Ahlbcrg, E. and Bcrghult,B. Electrochim Acta 35 (1990) 1213-1218.

30. Anodic oxidation of lead in sulphuric acid solutions.The effect of different pcrchlorate salts on plantéformation. Ahlbcrg, E. and Bcrghult, B. Journal ofPower Sources 32 (1990) 243-251.

31. The Polarization of Iron in Aqueous PcrchlorateSolutions; The Effect of Quality and Purity of theElectrolyte. Ahlbcrg, E. and FricI, M. J. Electrochcm.Soc. 137(1990)1196-1199.

32. The Anodic Dissolution of Iron Microclectrodes inAcidic Water-Acetonitrilc Solutions. Ahlbcrg, E. andFricI, M. Electrochimica Acta 35 (1990) 501-507.

33. An Electrochemical Investigation of the CorrosionBehaviour of Sintered Stainless Steels. Ahlbcrg, E.,Engdahl, P. and Johansson R. Proc. of the PM'90,Wembley, London, England (1990).

34. The surface oxidation of pyrite in alkaline solution.Ahlberg, E., Forssberg, K.S.E. and Wang, X. Journalof Applied Electrochemistry 20 (1990) 1033-1039.

35. Thesis: Fundamental Electrochemical Aspects of theLead Electrode in Connection with the Lead-AcidBattery. Bo Bcrghult (1990).

36. Bildningen av lustgas från kvävedioxid, svaveldioxidoch vattenånga. Börjesson, S. Projektarbete 20 p..Institutionen för oorganisk kemi, Chalmers TekniskaHögskola och Göteborgs universitet, 412 96 Göteborg(1990).

37. Luftföroreningarnas inverkan på byggnader ochmonument. Ett söndervittrande Göteborg. Börjesson,S., Lindqvist, O., Lundgren, H. and Rosvall, J. Instituteof Conservation, University of Göteborg, Sweden,1990:1 (1990).

38. Oxidation of Silicon Nitride. Chen, J., Sjöberg, J.,O'Meara, C. and Pejryd, L. Proc. 1 lth Ris0 Sympo-sium on Metallurgy and Materials Science (cd. J J.Bentzen et al.) (1990) 439444.

39. Electrochemical Studies on the Galcna/XanthatcSystem, Relationship to Flotation. Elfström Broo, A.ISSN 0283-8575, Report OOK 90:03,1-27.

40. Stone consolidation by tetraalkoxysilane treatment. Acase study on sandstone and limestone in medievalchurches on Gotland. Elfving, P. ISSN 0283-8575,Report OOK 90:08.

41. Kisclsyraesterbaseradstenkonscrvcring.Långtidsexponering på Gotländsk kalk- och sandsten.Elfving, P. ISSN 0283-8575, Report OOK 90:09.

42. The role of charge transfer and close packing in dopedY-123 materials. Eriksson, S.G. ISIS- report,Rutherford- Appleton- Laboratory A50,1990.

43. Synergistic effects of air pollutants on the atmosphericcorrosion of metals and calcareous stones. Johansson,L.-G. Marine Chemistry 30 (1990) 113-122.

44. Bestämning av kapaciteten au absorbera svaveldioxidhos svensk dolomiL Jäglid, U. and Lindqvist, O. ISSN0283-8575, Report OOK 90:01.

45. A Kinetic Study of Tetraethoxysilane in an AlkalineMedium in Methanol Solution. Jäglid, U. andLindqvist, O. Acta Chem. Scand. 44 (1990) 765-768.

46. Phonon characterisation of YBa2Cu3O7 doped with Aland Ga by Raman spectroscopy. Kakihana, M.,Börjesson, L. and Eriksson, S.G. Physica B165-166(1990) 1245.

47. Effect of Sr and Co doping on structure and phononRaman spectra of YBa2Cu3O7. Kakihana, M.,Börjesson, L. and Eriksson, S.G. Physica B165-166(1990) 1247.

48. Evidence for charge transfer in Y-123. Kakihana, M.,Eriksson, S.G., Börjesson, L. and Kall, M. Int. Conf. onSuperconductivity and its relating Character in LayeredCompounds, Yokohama, 1990.

49. The development of microstructure in pressurelesssintered Si2N2O bodies. O'Meara, C. and Sjöberg, J.Ceramic Transactions 7 (1990) 647-663.

50. Investigation of grate combustion of biomass fuels inan experimental furnace. Öländers, B, Report (1990).

51. Ammonia Adsorption on Synthetic Zeolities.Shambayati, P. Projektarbete 10 p. (1990).

52. A laboratory study of the atmospheric corrosion ofstatue bronzes and copper. Strandberg, H., Johansson,L.-G. and Lindqvist, O. Eurocare-Copal Report (EU316) (1990) 1-36.

53. Anodic Dissolution of Lead in Perchloric Acid Solu-tions: The Effect of Sulphuric Acid. Ahlberg, E. andBerghult, B. Electrochim. Acta 36 (1991) 197-201.

54. Anodic polarization of galena in relation to flotation.Ahlbcrg, E. and Elfström Broo, A. Int. J. of MineralProcessing 33 (1991) 135-143.

55. The Rate-controlling Processes in the Oxidation ofHIPpcd Si3N4 with and without Sintering Additives.Chen, J., Sjöberg, J., Lindqvist, O., O'Meara, C. andPejryd, L. Journal of the European Ceramic Society 7(1991)319-327.

56. The corrosion behaviour of HIP SJ3N4 and SiC/SiCcomposite in simulated combustion environments.Chen, J., Sjöberg, J., O'Meara, C. and Pejryd, L. Proc.4th Int. Symp. Ceram. Mater. Eng. (cd. R. Carlsson)(1991).



57. Atmospheric Corrosion on Silanc Treated Stones.Elfving, P. ISSN 0283-8575, Report OOK 91:04,1-57.

58. The formation of Sulfuric Acid, Nitrogen Monoxide,and Nitrous Acid on Gold in Air Containing Sub-ppmConcentrations of SO2 and NQ2. Eriksson, P. andJohansson, L.-G. J. Electrochem. Soc. 138 (1991)1227-1233

59. Powder neutron diffraction studies of the structuralchanges induced by charge transfer substitutions inhigh-Tc superconductors of the types Y-123 and Tl-2201. Eriksson, S.-G. and Ström, C. ISIS-reportRutherford-Appleton-Laboratory A42 (1991).

60. Neutron diffraction and Raman spectroscopic studiesof Y-123. Eriksson, S.-G., Johansson L.G., Ström, C,Berastegui, P., Börjesson, L., Kali, M. and Kakihana,M. Physica C185-189 (1991) 893.

61. Thesis: The Chemistry Behind the Sulfur DioxideRemoval by Calcium Oxide in Fluidizcd Bed CoalCombustion. Ghardashkhani, S. (1991) 1-73.

62. Some aspects of calcium sulphite reduction withcarbon monoxide. Ghardashkhani, S. and Lindqvist, O.Thermochim. Acta 190 (1991) 307-318.

63. Reaction Rates of Trimethylethoxysilane andTrimethylmethoxysilane in Alkaline Alcohol Solu-tions. Jäglid, U. and Lindqvist, O. Acta Chem. Scand.45 (1*591) 887-891.

64. Fabrication and characterisation of highly pure andhomogeneous YB^CirjOj. Kakihana, M., Börjesson,L, Eriksson, S.G. and Svedlindh J. Appl. Phys. 69(2)(1991).

65. High-quality ceramics of YBa2Cu4C>8 from citrate sol-gel precursors sintered at one atmosphere oxygenpressure. Kakihana, M., Kall, M., Börjesson, L.,Mazaki, H., Yasuoka, H., Bcrastegui, P., Eriksson,S.G. and Johansson, L.-G. Physica C173 (1991) 377-380.

66. Neutron diffraction and Raman spectroscopic studiesof Y-123. K9II, M., Kakihana, M., Börjesson, L,Ström, C, Johansson L.-G. and Larsson, T. PhysicaC185-189 (1991) 821.

67. Structural Changes in O'-Sialons, Si2.xAlxN2-xOi+x,0-045xS040. Lindqvist, O., Sjöberg, J., Hull, S. andPompe, R. Acta Cryst. B47 (1991) 672-678.

68. Thesis: The Influence of Various Air Pollutants on theSulfau'on of Calcareous Building Materials. Mangio, R.(1991).

69. Structure and Properties of Calcium Sulfate SulfiieDodecahydrate. Mangio, R., Langcr, V. and Johansson,L.-G. Acta Chem. Scand. 45 (1991) 572-577.

70. Mössbauer Study of the Site Preference for Fe Substi-tutions in Some YBa2Cu3<>7.y Compounds. Seidel, A.,Häggström, L, Min, P., Eriksson, S. and Johansson,L.-G. Phys. Scripta44 (1991) 71-73.

7 1. Thesis: On the Preparation and Structure of O'-Sialons.Sjöbcig.J. (1991).

72. Refinement of the Structure of S12N2O. Sjöberg, J.,Helgesson, G. and Idrestedt, I. Acta Cryst. C47 (1991)2438-2441.

73. Neutron diffraction studies of Tl-2201 andTl-2212doped with Lanthanum. Ström, C, Johansson, L.-G.,Eriksson, S.G., Kall, M., and Börjesson, L. PhysicaC185-189 (1991) 625.

74. Neutron diffraction studies of Tl-2201, Tl-2212 and Y-123 doped with Strontium. Ström, C, Johansson, L-G-, Eriksson, S.G., Kall, M. and Börjesson, L. PhysicaC185-189 (1991) 623.

75. Electrochemistry of carboxylic acids: mechanisticaspects of Kolbe-type reactions. Ahlberg, E. Supple-ment B: The Chemistry of Acid Derivatives 2, Ed. S.Patai (1992) 1250-1270.

76. Simulating Impedance Spectra from a MechanisticPoint of View: Theory and Simulations. Ahlberg, E.and Andersson, H. Acta Chem. Scand. 46 (1992) 1-14.

77. Simulating Impedance Spectra from a MechanisticPoint of View: Application to Zinc Dissolution.Ahlberg, E. and Andersson, H. Acta Chem. Scand. 46(1992) 15-24.

78. General corrosion of alloy X-750 under BWR condi-tions. Ahlbcrg, E. and Rcbensdorff, B. Water Chemis-try of nuclear reactor systems 6,2 (1992), 278-285.

79. Electrochemistry of sulphide minerals. Ahlberg,E.,Asbjömsson, J. and Elfström Broo, A. NUTEK B1992:6,128-158.

80. Corrosion of Water mains widi special respect to Iranpipes. Bcrghult, B., Elfström-Broo, A., Hedberg, T.and Lind Johansson, E. Proc. 12:th Scan. Corr. Cong.,Espoo Finland, May 1992,253-264.

81. Silanc Bonding to Various Mineral Surfaces. Elfving,P. and Jäglid, U. ISSN 0283-8575, Report OOK 92:01.

82. Thesis: Effects of SO2 and NO2 on metal surfaces:Atmospheric corrosion of copper and surface reactionson gold. Eriksson, P. (1992).

83. Powder diffraction studies of substituted Y-124, Tl-2201 , Tl-2212 and (Ba,Nd)2(Nd,Cc)2Cu3O8-d.Eriksson, S.-G., Ström. ISIS-report, Rutherford-Appleton-Laboratory A46 (1992).

84. Powder diffraction studies of the structural changesinduced by charge transfer substitutions in high-Tcsuperconductors of the types Y-123 and Tl-2201.Eriksson, S.-G., Ström. ISIS-report, Ruthcrford-Appleton-Laboratory A45 (1992).

85. Charge transfer and compression effects in Y-123.Eriksson, S.-G., Ström, C, Johansson L.-G. andSimon, A. Conference Proceeding, May 23-29,1992,Gaithcrsburg,USA.(1992).

86. A neutron diffraction study of YiBa2.ySryCu3.xMexO7.d (Mc= Co, Al, Fe), Eriksson, S.-G., Ström, C,Johansson L.-G., Simon, A. and Mattausch, Hj.Conference Proceeding, May 7-10,1992, Nyborg,Denmark.(1992).

87. The influence of carbon monoxide on the reactionbetween sulphur dioxide and calcium oxide.Ghardashkhani, S. and Lindqvist, O. Thcrmochim.Acia 195(1992) 113-128.

88. The influence of O2 on the reaction between CaO andSO2. Ghardashkhani, S., Lindqvist, O. and Tullin, C.

56 THE CENTRE FOR


89. Snabb kvantitativ fasanalys av bränsleaskor. Langcr,V. and Puromäki, K. Ptoc. Förpex-92,4-5 nov. 1992,Chalmers University of Technology, Sweden.

90. Characterization of ashes from wood and straw.Öländers, B. and Steenari, B-M. ISSN 0283-8575,Report OOK 92:03.

91. Fasanalys och smällförlopp hos askor från bark/spänoch halm. Öländers, B. and Steenari, B-M. Proc.Förpex-92,4-5 nov. 1992, Chalmers University ofTechnology, Sweden.

92. Testmetoder för sten samt studie av någrakonserveringsmedel för sten med hjälp av dessatestmetoder. Ryberg, M. and Elfving, P. ISSN 0283-8575, Report OOK 92:05.

93. Local structure of b'-sialons: an EXAFS study.Sjöberg, J., Ericsson, T. and Lindqvist, O. Journal ofmaterials Science 27 (1992) 5911-5915.

94. A neutron powder diffraction study of structuralchanges in -xBaaCuOM and Tl2.xBa2CaCu2O8-drelated to thallium and oxygen stoichiometry. Ström,C, Eriksson, S.-G., Johansson L.-G. and Simon, A.Conference Proceeding, May 7-10,1992, Nyborg,Denmark.(1992).

95. Neutron powder diffraction studies of structuralchanges in Tl2.xBa2Cu0frd and Tl2.xBa2CaCu2O8.drelated to thallium and oxygen content. Ström, C,Eriksson, S.-G., Johansson L.-G. and Simon, A.Conference Proceeding, May 23-29,1992,Gaithersburg,USA.(1992).

96. Electrochemical study of surface oxidation andcollcctorless flotation of arsenopyrite. Wang, X.-H.,Ahlberg, E. and Forssberg, K.S.E. Journal of AppliedElectrochemistry 22 (1992) 1095-1103.

97. An improved method of preserving and extractingmineral matter from coal by very low temperatureashing (VLTA). Shirazi A.R. and Lindqvist O. FUEL,72,(1993)125-131

98. ^ T l NMR in oxygen depleted cuprate superconduc-tors Tl2Ba2CaCu2O8-dN. Winzek, Hj. Maliausch, S.-G. Erueson, C. Ström, R. Kremer, A. Simon and M.Mehring. PhysicaC205,43 (1993)

99. Charge transfer and compression effects of isomor-phous substitutions in Y-123. M. Kakihana, S.-G.Eriksson, L.-G. Johansson, L. Börjesson and C. Ström.Phys. Rev B47, march issue (1993)

100. Control of carrier concentration in Y] .yCay Ba2Cu3_,Co,07^. S.- G. Eriksson, C. Ström and M. Kakihana.Conference Proceeding, ICMAS-93, Paris-Mame-la-Vallee, France.

101. Structure and superconducting properties ofd, Yi .yCayBa2Cu3.

7.d. S.- G. Eriksson,C. Ström and A. Simon. Conference Proceeding,ICMAS-93, Paris-Mame-la-Vallec, France

102. The effect of carrier concentration on structure andTc in TI-2212. The effect of carrier concentration onstructure and Tc in TI-2212. S.- G. Eriksson, C. Strömand N. Winzek. Conference Proceeding, ICMAS-93,Paris-Mame-la-Vallee, France.

103. On the AC Impedance of the Amalgamated ZincElectrode. Ahlberg, E. and Anderson, H., submitted forpublication.

104. Simulating Impedance Spectra from a MechanisticPoint of View: diffusion Effects in Metal DissolutionReactions. Ahlberg, E. and Anderson, H. Acta Chem.Scand., submitted for publication.

105. Carbon Paste Electrodes in Mineral Processing: AnElectrochemical Study of Galena. Ahlberg, E. andAsbjörnsson, J. Hydrometallurgy, accepted for publica-tion.

106. Polymerised complex synthesis of a pure 93 KY2Ba4Cu7Oi5.d superconductor without the need ofhigh oxygen pressure and additive catalysts. P.Berastegui, M. Kakihana, H. Mazaki, H. Yasuoka, L-G. Johansson, S.- G. Eriksson, L. Börjesson and M.Kail. J. Appl. Phys., accepted for publication.

107. On the effect of thallium and oxygen stoichiometryin Tl-2201 and TI-2212 on structure and Tc. C. Ström,S.- G. Eriksson, L.- G. Johansson, Hj. Mattausch, R.Kremer and A. Simon. Submitted for publication toJSSC.

108. Depression of Tc in Y-123 by a combination ofcobolt doping and oxygen depletion. S.- G. Eriksson,C. Ström and M. Kakihana. Physica C , submitted forpublication.

109. The influence of calcium and oxygen content onsuperconducting properties in the Yj.yCayBa2Cu3.xCoxO7.<i system. S.- G. Eriksson, C. Ström, M.Kakihana and A. Simon. Physica C, submitted forpublication.

110. Review on synthesis of cuprate based High-Tc

superconductors by a polymerized complex method.M. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuoka,S.-G. Eriksson, P. Berastegui, C. Ström, M. Kail and L.Börjesson. Jap. J. Appl. Phys., submitted for publica-tion.

111. Direct Quantitative Analysis of Mineral Matter andDifferent Pyritic Sulphur in Coal by Electron ProbeMicro Analyzer (EPMA) and Automatic ImageAnalyis (AIA). Shirazi A.R., Eklund L. and LindqvistO. To be published.

112. Nilsson O. "A Bipolar, High Power Density, LeadAcid Battery". To be published.


Reaction Dynamics

Research SummaryThe group has used extremely rapid desorptionkinetics as a means of studying the dynamics ofmolecule-surface interaction, with the shortestdesorption time constants for alkali atoms measureddown to 100 ns. In such a case, an atom jumpsthermally on the average only 105 times before itleaves the surface. The alternative method of study-ing the dynamics of interaction between moleculesand surfaces is to scatter a molecular beam off asurface. In the case of a heavy molecule and a lightsurface, like a graphite layer, the impinging mol-ecule can not reverse its direction in one collisionwith the surface. The dynamical insight gained insuch experiments also made it possible to explain thelong-standing problem of the rotational tempera-tures of scattered molecules, often being much lowerthan the surface temperature.

Under many conditions, electronically excitedand thus easily field ionizable states like Rydbergstates are formed in large densities in emission afterdiffusion through the bulk of graphite, or through athin surface layer of graphite on a metal. At lowdensities, mainly ordinary Rydberg states are formed,but at higher densities, electronically excited clustersare formed. Rydberg states are also formed at alkalipromoted industrial catalyst surfaces at ordinaryoperating temperatures, for example at the iron-based ammonia catalyst. The new information onemission energies and kinetics of desorption ofalkali from catalysts has even made it possible todeduce the detailed internal energetics for alkali inthe catalysts.

From a material point of view, a very interestingdevelopment is the stabilization of an excited type ofmatter. This new type of matter is formed fromcondensing Rydberg states, and it is thus calledRydberg matter. Macroscopic amounts of such amatter can be stabilized in vacuum for hours. Prop-erties like conductivity and work function have beenstudied. Rydberg matter has very special properties,as expected, for example the work function is below

0.5 eV. This probably makes it the best electronemitter available, giving experimental current densi-ties of >500 A/cm2 at 800 K. These experimentalresults agree with theoretical quantum mechanicalpredictions.

AddressDepartment of Physical Chemistry, GUChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 2832Fax+46 31 772 3107

StaffSenior Members:LeifHolmlidJan DavidssonJan Pettersson

docentfil.dr.fil.dr.

Graduate Students:Jörgen LundinRobert SvenssonCarina ÅmanTony HanssonElisabeth WallinKlas EngvallBo Olsson

Technical Staff:Benny LönnThomas Hessel

civ. ing.fil. lic.civ.ing.kemistkemistfil lickemist

Research EngineerTechnician

SecretaryMaj Levin (shared with the department)

58 THE CENTRE FOR

REACTION DYNAMICS

Major Instrumentation• Surface scattering UHV apparatus with rotat-

able (120°) quadrupole mass spectrometer (m/z 250), SIMS ion gun at 2.5 keV withrastering, three stage differentially pumpedmolecular beam source for 1 bar pressure withchopper

• Desorption and surface scattering UHV appa-ratus with rotatable detectors (360°):Quadrupole mass spectrometer (m/z 200),Weak field ionization detector, Surface ioniza-tion detector, and a differentially pumpedalkali metal molecular beam source withchopper

• Desorption apparatus with linear time-of-flightmass spectrometer for cluster studies, at timeresolution of <1 ms

• Apparatus for surface desorption studies atsurface life-times down to 30 ns with the fieldreversal technique

• Apparatus for cluster formation studies withquadrupole mass spectrometer

• Open thermionic energy converter (TEC) forsurface and Rydberg matter (condensedplasma) studies

• Pulsed Nd:YAG laser (8 ns), with frequencydoubling

• Infra-red diode laser (lead salt laser)spectrometer for molecular spectroscopy, line-width 0.001 cm-i

Major Reids of ResearchA: Molecule-surface Interactions

participants: T. Hansson, L. Holmlid, G.Nyman, J.B.C. Petterssoncollaborators: Ecole Polytechnique, Paris;Fysikalisk kemi GU

B: Electronic excitation of atomsand molecules at surfaces

participants: J. Davidsson, T. Hansson, L.Holmlid, J. Lundin, A. Kotarba, B. Olsson,J.B.C. Pettersson, E. Wallin, C. Åmancollaborators: State University of Ghent;Jagiellonian University, Cracow; Norsk Hydroa.s., Chemetall GmbH

C : Electronically excited matterparticipants: J. Davidsson, L. Holmlid, B.Olsson, J.B.C. Pettersson, R. Svensson, E.Wallin, C. Åman, L. Lundgrencollaborators: Kurchatov Institute, Moscow;JSB Ingenjörsbyrå, Trosa

Research ProjectsA: Surface - molecule interactionsAl : DesoiptkMi and diffusion kinetics

of alkali metals on graphiteand metal surfaces

Ordinary pyrolytic graphite surfaces (basal surfaces)have many special properties compared to metalsurfaces: they are extremely inert even at high tem-peratures, they adsorb many molecules without dis-sociating them, and they allow rapid migration intothe surface, eventually giving macroscopic interca-lation. The complicated energetics for alkali atomson graphite surfaces has been studied with highresolution at extremely short desorption life-times.Desorption from metal surfaces with small islands ofgraphite is studied, showing preferential desorptionthrough the islands after diffusion on the surface[10]. Laser desorption is used to study the desorptionprocesses at very low temperatures, giving together6 orders of magnitude in the rate constants [311. Withrapid kinetics and time-of-flight, it is shown that alarge part of the ioniza tion taking place isdue to fieldionization of Rydberg states, and not to surfaceionization [17]. In fact, it is likely that the processbelieved to be surface ionization does not exist at all.

A2: Surface scattering from graphite surfacesThe special vibrational properties of the basal sur-face of graphite and the energy transfer at the surfacehave been studied by surface scattering. In the caseof a heavy molecule and a light surface, like agraphite layer, the impinging molecule has to makeseveral jumps on the surface, which is seen in thescattering angular distributions for Xe and SF6 [6].The much studied "rotational cooling" of NO mol-ecules scattered from graphite has been explained asdue to the very small lateral energy barriers on thesurface coupled to angular momentum conservation[8]. The angular distributions for argon and nitrogencluster beam scattering from graphite have beenmeasured in another laboratory. The clusters are


REACTION DYNAMICS

heated at surface impact and fragmentize dependingon the available energy. This fragmentation processhas been studied with classical trajectory calcula-tions, and is well described by evaporation of smallfragments from the parent cluster [32].

B. Electronic excitation of atoms andmolecules at surfaces

Bl: Rydberg states of alkali and hydrogenat graphite surfaces due to bulk diffusion

The emission of alkali atoms from high temperaturesurfaces gives a large fraction of electronically ex-cited atoms, partly in Rydberg states [1]. This isexpected since the surface-vacuum interface is not inthermal equilibrium. Also the ions are excited andeven negativeexcited ionscan be formed [4]. Rydbergatoms will interact strongly with surfaces, and theywill probably diffuse rapidly into the material. Thistype process was observed previously in kineticsstudies, but is now observed in a beam-surfaceexperiment [28]. Also hydrogen molecules giveRydberg states in diffusion sources, and the tempera-ture dependence as well as the time dependence atthe detector are studied [16,25]. The time constantsof the field ionization process are measured, andturns out to be similar to ordinary radiation lifetimes[12]. Other excited states of cesium can also beformed under some conditions, giving Cs2+ in fieldionization [2]. By forming surface layers fromRydberg states of alkali, it iseven possible to observethe ion H2. in a mass spectrometer [18]. This ion isnot stable in its ground state, and thus the observedstate must be in a Rydberg state, which can have amuch longer life-time.

B2: Rydberg states of alkali promoterat catalyst surfaces

Many commonly used heterogeneous catalysts arepromoted with alkali. One very common class con-tains metal oxides, and this type of porous catalyst isshown to emit large fluxes of Rydberg states atordinary process temperatures. The first examplesstudied is an iron oxide catalyst used for styreneproduction [9,14], and the vanadium oxide catalystfor SO3 production [15]. The complicated internalenergetics for alkali in the complex and porouscatalyst material is studied in detail. Field ionizationis used to identify the Rydberg states [22]. The

formation of Rydberg stateson industrial catalysts iscertainly coupled to the loss of alkali promoter in theprocess [24], but maybe also to the promoter func-tion, as predicted previously [5]. Angular resolveddesorption is used to identify also cluster formationand desorption from the catalysts [24,27]. Novelsurface scattering features are observed, as well asangular patterns for ion desorption which resemblechannelling, with lobes of a few degrees width[27,30]. Similar behaviour is also found for metalliccatalysts.

C: Electronically excited matter

Cl: Excited clusters of alkali metaland hydrocarbons

At higher densities of Rydberg states outside sur-faces, the extremely large interaction potential be-tween the Rydberg states gives rise tocluster forma-tion. The masses of the field ionized clusters aredetermined by time-of-flight mass spectrometry,and typical clusters obtained contain 4,000-10,000Csatoms[7],ormassesof 10,000-200,000 a.u. in thecase of hydrocarbon molecules [23]. The sourceused to form such clusters employs diffusion througha carbon foil [19]. Also the emission of alkali frommetal oxides (heterogeneous catalysts) gives rise toformation of clusters [24,27].

C2: Surface layers of condensedexcited states (Rydberg matter)

If beams of Rydberg and other electronically excitedstates like clusters impinge on surfaces, quite stablesurface layers of excited states can be formed. Suchlayers can be observed when they deexcite explo-sively, giving off visible light [11]. They can also beobserved from the current given off to the supportwhen the impinging beam is cut off [25]. Further,they can be employed to give surfaces with low workfunctions, which can transfer electrons to moleculesto give negative ions [18].

C3: Rydberg matterAn excited form of matter can be formed by conden-sation of Rydberg states, as predicted by theory.Macroscopic amounts, several mm3, of so calledRydberg matter can be formed easily and maintainedfor many hours in experiments where excited statesof cesium are formed in contact with a carbon

60 THE CENTRE FOR

REACTION DYNAMICS

covered surface! 13]. Rydberg mattercan be formedat temperatures of 500-800 K by this method, and itcan be observed and studied. The resistivity is low,of the order of 10-2 - 10-3 Q m [13]. The workfunction is very low, at least smaller than 0.7 eV andprobably smaller than 0.5 eV [21]. These resultsagree with theoretical calculations by a group atKurchatov Institute in Moscow. The potential distri-bution in a sheath of Rydberg matter has been studied[26] and agrees with the other results. A technicalapplication of Rydberg matter is developed, and apatent is applied for [20] in the form of an improvedthermionic energy converter. When Rydberg matteris formed inside an electrode with small opening init, Rydberg maner leaks out to the outer surface,giving very low work functions at high tempera-tures. This type of construction is intended for anovel electrode for use in magnetohydrodynamicenergy converters [29].

PublicationsPh. D. DissertationJ.B.C. Pettersson, "Excitation of atoms and molecules at

surfaces: inelastic scattering and excited state emis-sion". (1990).

Licentiate DissertationsR. Svensson, "Highly excited states in an electronically

controlled thermionic energy converter". (1990).

K. Engvall, "Experimental studies of industrial alkalidoped catalysts: emission of excited alkali species".(1992).

Reports and articles1. "Rydberg states of cesium in the flux from surfaces at

high temperatures", J.B.C. Pettersson and L. Hoimlid,Surface Sci. 211 (1989) 263-270.

2. "Sampling of a hot Cs plasma with a QMS in athermionic energy converter", J. Lundin and L.Holmlid, "Advances in Mass Spcctromctry", Vol. 11A(Ed. P. Longevialle), Heyden & Son, London, 1989, p.204-205.

3. "Surface ionizauon at atmospheric pressure. II.Particles of inorganic alkali salts and of sodiumdodecyl sulphate", L. Holmlid and S. Wall, Langmuir 5(1989)1170-1175.

4. "Large fluxes of highly excited caesium ions from adiffusion source". T. Hansson, C. Äman, J.B.C.Pettersson and L. Holmlid, J. Phys. B: At. Mol. Opt.Phys. 23 (1990)2163-2171.

5. "Alkali promoter function in heterogeneous catalysis:possibility of interaction in (he form of Rydbergstates", J.B.C. Pettersson, L. Holmlid and K. Möller,Appl. Surface Sci. 40 (1989) 151-154.

6. "Inelastic surface scattering of Xe and SF<, fromgraphite surfaces at high temperatures", J.B.C.Pettersson, A. Sigurdsson, G. Nyman and L. Holmlid,Surface Sci. 232 (1990) 329-338.

7. "Field ionizablc cesium metal clusters from a foildiffusion source". C. Åman, J.B.C. Pettersson and L.Holmlid, Chcm. Phys. 147(1990) 189-197.

8. "Surface scattering of NO from graphite: a statisticaldescription of energy distributions", G. Nyman, L.Holmlid and J.B.C. Pettersson, J. Chcm. Phys. 93(1990)845-853.

9. "Mechanism of potassium loss by dcsorplion from aniron oxide catalyst for the styrcne process", J. Lundin,K. Engvall, L. Holmlid and P.G. Menon, Catal. Letters6(1990)85-94.

10. "Rate constants for cesium desorption and lateraldiffusion on indium with graphite islands: parallelprocesses studied by field reversal", T. Hansson, J.B.CPettersson and L. Holmlid, Surface Sci. 253 (1991)345-352.

11. "Visible luminescence from panicles on surfaces:evidence of decxcilation of Rydberg matter", J.B.C.Pcttcrssson, H. Lindroth, C. Åman and L. Holmlid, J.Mat. Research 7 (1992) 100-104.

12. "Rydberg states of caesium from a diffusion source:pulsed field ionization and life-times", C. Åman and L.Holmlid, J. Phys. D.: Applied Physics 24 (1991) 1049-1053.

13. "A semi-conducting low pressure, low temperatureplasma of cesium with unidirectional conduction", R.Svensson, L. Holmlid and L. Lundgren, J. Appl. Phys.70(1991)1489-1492.

14. "Comparative loss of alkali promotor by desorptionfrom two catalysts for the dchydrogenation of ethylbenzene to styrene", K. Engvall, L. Holmlid and P.G.Mcnon, Appl. Catal. 77 (1991) 235-241.

15. "L iss of alkali promoter by desorpuon from promotedvanadium oxide catalysis", K. Engvall, L. Holmlid, H.Prinz and H. Hofmann, Catal. Letters. 11 (1991) 41 -48.


REACTION DYNAMICS

16. "Excited states of hydrogen emitted from a graphitediffusion source: Arrhcnius behaviour", E. Wallin andL. Holmlid, Chem. Phys. 159 (1991) 313-319.

17. "Field ionization of cesium atoms diffusing out from anindium foil, studied by time-of-flighi massspectrometry", E. Wallin, T. Hansson and L. Holmlid,Int. J. Mass Spectrom. Ion Proc. 114 (1992) 3145.

18. "Negative ions tormed at grid surfaces in a flux ofexcited Cs atoms and ions", J. Lundin and L. Holmlid,Int. J. Mass Spectrom. Ion Proc. 114(1992) 137-147.

19. "Source for excited states of alkali atoms and clustersusing diffusion through a thin graphite foil", L.Holmlid, J.B.C. Pettersson, C. Aman, B. Lönn and K.Möller, Rev. Sci. Instrum. 63 (1992) 1966-1968.

20. "Kollcktor med lågt uurädesarbetc förteimojonomvandlare". L. Holmlid and R. Svensson,Patent application nr 9102263-2. Accepted.

21. "Very low work function surfaces from condensedexcited states: Rydberg matter of cesium", R. Svenssonand L. Holmlid, Surface Sci. 269/270 (1992) 695-699.

22. "Field ionization of excited alkali atoms emitted fromcatalyst surfaces", K. Engvall and L. Holmlid, Appl.Surface Sci. 55 (1992) 303-308.

23. "Hydrocarbon clusters from a foil diffusion source", C.Åman and L. Holmlid, J. Cluster Sci. (1992).

24. "A new approach to loss of alkali promoter fromindustrial catalysts: importance of excited states ofalkali", L. Holmlid, K. Engvall, C. Åman and P. G.Menon, International Congress of Catalysis, Budapest1992. Oral presentation, to app&. < in proceedingsvolume.

25. "Highly excited Rydberg states of hydrogen from ahigh temperature diffusion source", E. Wallin, T.Hansson and L. Holmlid, J. Phys.: Condensed Matter(9) (1992).

26. "Temperature studie 5 and plasma probing of a Rydbergmatter collector in a thermionic energy converter", R.Svensson and L. Holmlid, Paper No. 929430,27rdInicrsociety Energy Conversion Engineering Confer-ence, (IECEC 1992, San Diego), Society of Automo-tive Engineers, Warrcndalc 1992, Vol. 3, p. 537-542.

27. "Dcsorption and emission of potassium Rydberg atomsand clusters from iron oxide catalyst surfaces". C.Åman and L Holmlid, Appl. Surface Sci. (1992).

28. "Large hysteresis effect in surface ionization of Cs dueto bulk diffusion", T. Hansson and L. Holmlid, SurfaceSci. (1992).

29. "High emissivity electrodes for MHD channels", R.Svensson, K. Engvall, L. Holmlid, J. Braun and L.Lundgren, 1 lth International Conference on MHDelectrical power generation, Beijing, 92-10-12-16.

30. "Field ionization of Rydberg alkali states outside ironoxide catalyst surfaces: peaked angular distributions ofions", C. Åman and L. Holmlid, Appl. Surface Sci.(1992).

31. "Rate constants for thermal cesium ion dcsorpiion onclean and graphite-covered indium studied by laser-induced desorption", T. Hansson and J.B.C. Pettersson,Surface Sci. 269/279 (1992) 189-194.

32. "Dynamics of cluster scattering from surfaces", J.B.C.Pettersson and N. Markovic', Chcm. Phys. Letten(1992).

62 THE CENTRE FOR

SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE

Chemical Analysis

Research SummaryThe emphasis of R&D work at the department ofChemical Analysis is on the development of instru-mentation and methods that allow specific proper-ties or compositions of materials and products to bemeasured such that unambiguous interpretation ofthe results can be made. Another theme is the closeexamination of some particular property of materi-als cr groups of products that influence the suitabilityfor their end use.

The main areas of R&D may be referred to as'Indoor Air quality', 'Energy-Environment', 'Poly me-ric Materials' and 'Building Materials' (inorganic).Measurements of emissions of organic compounds,in particular formaldehyde from e.g. chip board, andVOC (volatile organic compounds) from e.g. floor-ing materials, is a continuing contribution to effortsfor creating a sound indoorenvironment. Characteri-sation of fuels of various types, lately in particulargasoline and diesel fuels (e.g. its total content ofpolyaromatic hydrocarbons), is one theme related toconsiderations of the environment in general. An-other theme that has been, and is focused on is thetracing of residues ot CFC from the manufacturingof polymeric foams.

Life-cycle studies are becoming part of the R&Dwork. Also, characterisations other than determina-tions of composition and ordinary physical proper-ties are getting increasingly important for varioustype residues as a basis for decisions on their safe usein new applications rather than having to be paid foras land-fill.

Another R&D field for analytical chemistry is thepreparation of samples and/or preseparation of com-ponents required before qualitative as well as quanti-tative analysis can be made. In a number of p* ojectsdealing with the characterisation of polymeric mate-rials, e.g. in determinations of type and amount ofplasticizers, fillers, antioxidants and other additivesto polymers, the design and checking of such pretreatment is the more demanding part.

AddressSwedish National Testing and Research InstituteChemical AnalysisBox 857S-50I 15 Boras, SwedenPhone+46 33 165000Fax+46 33 12 37 49

StaffSenior MembersBjörn LundgrenKarin BerglundLars CedheimHans GustafssonLars JohnsonMargret MånssonClaus R0yemLars Winnerstam

SecretarySonja Mozer-Rosell

fil.dr., head of departmenting.fil.dr.apotekarex.fildr.docentfiLlic.civ.ing.

Major Instrumentation• ICP Emission Spectrometer, Chus R0yem• WD-XRF, Lars Winnerstam• NMR, Lars Cedheim• Flame AAS, Graphite-Furnace AAS,

Claus R0yem• GC-MSD,GC-ECD,GC-FID, Lars Johnson• HPLC,GPC,IC,TLC, Lars Cedheim• Elemental analysers: C-H-N, C-S, S,

Karin Berglund• Emission chambers (VOC, formaldehyde)

1 and 17 m3, Björn Lundgren• Bomb Combustion Calorimeter,

Margret Månsson

Only limited direct access for external users, but co-operative programs are possible.


SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - CHEMICAL ANALYSIS

Major Fields of Research

A: Indoor Air QualityParticipants: Björn Lundgren, Hans Gustafsson,Ingrid Isaksson, Lars Johnson, Bengt Jonsson, LarsRoseliCollaborators: CTH, KTH, SBI (Denmark) andGroups in Europe

B: Energy - EnvironmentParticipants: Bjöm Lundgren, Margret Månsson,Karin Berglund, Lars Cedheim, Jolanta Karlsson,Peter Marstorp, Karl-Axel Olsson, Lars Winnerstam

C: Polymeric MaterialsParticipants: Bjöm Lundgren, Lars Cedheim, PerBlomqvist, Per Lindberg, Margret MånssonCollaborators: CTH

Research projects

A: Indoor Air QualityA number of projects can be referred to under thisheading. They represent a) development/compari-sons of equipment and techniques for measuringchemical emissions from products or materials, b)studies of various types of emissions from groups ofproducts and c) examinations of amounts and typesof organic compounds in indoor air. - Also, consultlist of publications.

FLEC - Sampling for measurementsof emissions of VOC.

A l : Held and Laboratory Emission Cell - FLECDevelopment of a small, easy-to-handle emissioncell for measurement of volatile organic compoundsemitting from planar materials. The cell is designedfor use in the laboratory, on site in buildings, and forproduct developmentandproductioncontrolofbuild-ing materials. The construction of the cell ensures auniform air velocity over the enclosed surface of thetest material. A protocol for measurements withFLEC has been defined. Developed in co-operationwith AMI and SBI in Denmark.

A2: European Investigation on the Comparabilityof Large Chamber Tests on FormaldehydeEmissions from Wood Based Panels

This is one example of joint efforts at the Europeanlevel to establish to what extent experimental condi-tions in terms of chamber volume, material ofconstruction of the chambers, dimensional propor-tions, air velocity, technical handling etc. lead tosignificant differences in the results obtained. Largechamber volumes vary e.g. between 12 and 80 m3.Other European projects aim at establishing correla-tions between results obtained using 'small' (1 m3 orless) and between small and large chambers.

A3: Characterisation of Chemical Emissionsfrom Concrete Admixtures

This project is a study of whether and to what extentconcrete admixtures contribute to indoor air che-mical emissions from building materials.

A4: The Effect on Flooring Materialsfrom Damp Concrete

A study of how and to what extent damp concreteeffects P.ooi" covering materials. The measurementsat SP are concerned with the effects on the chemicalemissions from the flooring materials. Three types ofvinyl flooiing and one linoleum material are in-cluded in the study. The concrete moisture levelschosen are those corresponding to 95 %, 85 % and50% RH, respectively. Measurements (FLEC) areplanned for 54 combinations of material-'moisturelevel'.

A5: Experiences from the Developmentof Low-Emission Building Materials

In this project available general knowledge andexperience from the development of low-emissionmaterials and constructions is to be summarised for

64 THE CENTRE FOR


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0.1 0.2 0.3 0 A 0,5 0.6 0.7

oJrchanges per hour

0.8 0,9

TVOC as a function of the degree of ventilation for the individual home.

the benefit of the 'users' (architects/designers, build-ers, building contractors etc.). Efficient ways ofdistributing this information between variousbranches of the building industry and producers ofbuilding material are to be developed.

A6: Air quality In residential housingA survey of indoor air quality in 40 to 50 one-familyhouses built in the period 1983 - 1990. The studyincludes determinations of the total amounts ofvolatile organic compounds (TVOC) with identifi-cation of major components and measurements ofthe actual ventilation for comparison with the regu-latory values for this type of houses.

B: Energy - Environment

Bl: Polyaromatic Hydrocarbons in Diesel FuelsFor environment/tax purposes diesel fuels are as-signed to different classes depending on amongother things their content of polyaromatic hydrocar-bons (PAH). In this project a method for measuringthe total amount of PAH was designed. The methodin fact also defines what is meant by "total PAHcontent". The determinau'ons had to be reasonably.ample to carry out. The uncertainty of the measure-ments must of course be small enough to allowproper differentiation according to the classificationsystem for the fuels.



10 15 20 30 35

PAH in diesel fuels - HPLC method: D = PAH, reversal of flow at R.(A- aliphatic, B- benzene and C- naphtalene type hydrocarbons).

B2: Calorimetrfc Determinations of Energies/Enthalpies of Combustion (Calorific Values)

Bomb calorimetric measurements is an area whereChemical analysis has a lot of experience frommeasurements of high accuracy toroutine determina-tions on liquid and solid fuels. Lately, projectsconcerned with the revision/rewriting of standardmethods (ISO 1928; solid fuels) and devising in-struction material for this type of measurements onmaterials other than fuels (Nordtest; building mate-rials) have been carried out.

C: Polymeric Materials

Cl: Chromatographic Preseparation ofComponents in Polymeric Materials

Equipment was installed and tested, and strategieswere designed for the separation of componentsprior to analysis of products based on polymericmaterials. The chromatographic techniques utilisedare TLC, HPLC, SEC and open column chromatog-raphy. -An optical densitometer and equipment forquantitative TLC-analysis were added to the exist-ing analysis system.

C2: Methods of Analysis for Trace Amountsof CFC In Polymeric Foams

When restrictions in Sweden on the use of CFC in themanufacturing of polymeric foams were comple-mented by import restrictions on CFC-manufactu-red foams, analytical methods for tracing CFCresidues were required to make such legislationmeaningful. It had been shown in a previous projectthat trace amounts of CFC could be traced also infoams with open cells where CFC has only been amanufacturing aid and not an intended component ofthe product.

66 THE CENTRE FOR


PublicationsDiploma woikEllen Ekelund: "Bestämning av svavel, fosfor och bly ibensin med plasmaemissionsspektroskopi (ICP)", SP-AR1992:20. Spring 1992.

Reports and articles1. "Building Materials Identified as Major Sources for

Indoor Air Pollutants - A Critical Review of CaseStudies" Hans Gustafsson, Byggforskningsrådet,D10:1992.

2. "Byggnadsmaterial och emissioner" Hus & Hälsa -Kunskapsbas: U6.1992, BFR. Björn Lundgren, HansPettersson m fl.

3. "Field and Laboratory Emission Cell: FLEC" P.Wolkoff, P.A. Clausen, P.A. Nielsen, H. Gustafsson,B. Jonsson, E. Rasmusen, Conf. Proceedings 'HealthyBuildings' Sept. 4-8,1991; p 160-165. Washington,D.C.USA.

4. "Review of Small Scale Devices for MeasuringChemical Emission from Materials" Hans Gustafsson,Bengt Jonsson, SP Report 1991:25.5. "FormaldehydeContents in Swedish Chipboard. A Comparisonbetween Different Laboratories" Rune Ziethén, BengtJonsson, SP Report 1989:25.

6. "Materialval och kemiska emissionsdata" HansGustafsson, AMA-NyU Mark • Hus 2/92, p 40 - 43.

7. "CFC in Polymeric Foams, Tracing CFC Residuesfrom the Manufacturing" Mats Olsson, MargretMånsson Björn Lundgren, Nordic Council of Minis-ters, Miljörapport 1989:3.

8. "Methods of Analysis for Trace Amounts of CFC inPolymeric Foams" Olle Jacobson, Margret Månsson,Mats Olsson, Nordic Council of Ministers, Nord1991:17.

9. "Nedbrytning av glykoler i värmepump ochsolvärmesystem. Laboratorieundersökning" LarsCedhcim, Ulla Blume, Björn Lundgren,Byggforskningsrådet, R107:1988.

10. "Fysikalisk-kemiska studier av tillsatsmedel i polymeramaterial" Lars Cedheim, SP Report 1989:30.

11. "Förlaga till reviderad ISO 1928 för kalorimetriskabestämningar av värmevärdct fär festa bränslen"Margret Månsson, Värmeforsk, SVF438.

12. "Determinations of Calorific Va'ues of BuildingMaterials - A Guide" Margret Månsson, Nordtestproj.871-90,SP Report 1991:15.

13. "Miljörclatcradc egenskaper 'ios eldningsoljor. Enkvalitctsundcrsökning" Karin Berglund, ElisabethEkberg, Margrel Månsson, Mats Rignell,Naturvårdsverket Rapport 4013.


Polymers and fibresMaterials Physics 70Polymer Technology 78Polymeric Materials 87Polymer Technology and Surface



The Swedish Institute of Fibreand Polymer Technology, IFP-PGI 106


Materials Physics

Research SummaryOur research program concerns structure and dy-namics of disordered systems (glasses, polymers,ceramics, etc.) especially energy related materials(ion conducting glasses, polymeric electrolytes, hightemperature superconductors, etc.) using laser lightand neutron scattering methods. The light scatteringinvestigations are performed at Chalmers usingadvanced Fabry-Perot-, Raman-, and photon corre-lation techniques. Neutron scattering is performed atthe international facilities at ISIS (Oxford) and ILL(Grenoble).

Seeking to explain the dynamics of the glasstransition we investigate various glassformingmate-rials over the enormous time range of 10-12s to Is.We show that by changing the network formingability of the glass, the dynamics is changed in asystematic way, as reflected in the relaxation func-tion (non-exponential in time, non-Arrhenius intemperature). Comparisons are made to recent theo-ries for the liquid-glass transition, e.g. hierarchical vsparallel relaxation theories, mode-coupling etc.

It is found that ion conducting glasses exhibitstrong correlations in the intermediate range order.This suggests that the dopant salt forms a percolatingnetwork which is decoupled from the host glass andproposed to be fractal. Such an interconnected sub-structure may provide the conduction path way whichallows for the anomalously high ionic conductivity.

In the work on polymeric electrolytes we inves-tigate structural properties for an optimized chargetransport. We demonstrate that the unfortunate andmuch debated conductivity drop at large salt concen-trations is due to crosslinking phenomena whichresult in reduced ionic mobility.

Raman experiments on high-Tc superconductorsreveal direct correlations between Tc and the latticevibration frequency of the bridging oxygen atomsbetween CuO2 superconducting planes and CuOchains in samples of YBa2Cu3O7-d subject to oxy-gen deficiency or selective substitution. 1 he resultsstrongly support recent charge transfer m xlels forhigh temperature superconductivity.

AddressDepartment of PhysicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone +46 31 772 317Fax+46 31 772 3177

StaffSenior MembersLena M. TorellLars BörjessonStaffan SchantzPer JacobssonDavid Sidebottom

Graduate StudentsStaffan SchantzMats ElmrothMikael KallJan SwensonRikard BergmanBritta MatssonDennis EngbergAbdel Hassan

6

professordocentfil. dr (-90)fildrdr

filkand. (-89)fil.kand.civ.ing.fil.kandfiLkandciv.ingciv.ingM.Sc.

Major Instrumentation• Lasers: Spectra Physiscs Ar-lasers, He-Ne lasers

and dye lasers, equipped for single-modeoperation.

• Fabry - Perot Interferometers: Pressure scannedsingle-pass interferometer (model Hilger &Watts); Piezo electrically scanned triple-passinterferometer (model Burleigh); Piezo electri-cally scanned six-pass tandem interferometer(model Sandertock).

• Raman spectrometers. Spex double monochro-mator equipped with third monochromator.Spex triple spectrograph.

• Raman Microprobe (Nikon Instruments)

70 THE CENTRE FOR

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Photon Correlation Equipment. ALV 5000photon correlator.

Detectors. 2-dim CCD-detectors (WrightInstruments); cooled photomultiplier-detectors.

Cryostats (4K-700K)/furnaces (300-1500K)Oxford instruments developed for light scatter-ing.

Major Fields of ResearchA: Structural glasses and the glass transition.

Participants: Lena Torell, Lars Börjesson, MatsElmroth, Dennis Engberg, Abdel HassanDavid Sidebottom (Dr, Kansas State Univ.,USA), Matthias Fuchs (Dr. Univ. Munich,Germany)Collaborators: Austen Angell (Prof, ArizonaSt. Univ., USA) Aldo Fontana(Prof, TrentoUniv., Italy)

B: PolymersParticipants: Lena Torell, Lars Börjesson,Rikard Bergman, Per Jacobsson, Mats Elmroth,Jim Stevens (Prof, Guelph Univ., Canada)Collaborators: Alexander Brodin (Dr, Univ.Kiev, Uraina), Spencer Howells (Dr, ISIS, U.K.)

C: Fast ion conducting glassesParticipants: Lena Torell, Lars Börjesson, MatsElmroth, Abdel Hassan, Jan SwensonCollaborators: Aldo Fontana (Prof, Trento Univ.,Italy), Reneé Vacher (Prof, Univ. Montpellier,France), Robert McGreevy (Dr, ClarendonLab., Oxford, U.K.), Spencer Howells (Dr,ISIS, U.K.), Kurt Sköld (Prof, Studsvik,Sverige)

D: Polymeric electrolytesParticipants: Lena Torell, Lars Börjesson,Staffan Schantz, Dennis Engberg, BrittaMatsson, Greger Pedersén, Per Jacobsson, JimStevens (Prof, Gueiph Univ., Canada), MasatoKakihana (Dr, Tokyo Inst. of Techn, Japan)Collaborators: Bruno Scrosati (Prof, RomeUniv., Italy), Michel Armand (Prof, ENSEEG,France), Colin Vincent (Prof, Univ. St. Aidrews,U.K.), Michel Smith (Prof, Lisbon Univ.,Portugal)

E: High temperature superconductorsParticipants: Lars Börjesson, Mikael Kall,Alexander Litvinchuk (Dr MPI, Stuttgart,Germany), Girsh Blumberg (Dr EstonianAcad. Sci Estonia), Hoang Van Phuong(M.Sc., Hanoi Univ. Vietnam), Lee Van Hong(Dr. Hanoi, Univ. Vietnam), Masato Kakihana(Prof, Tokyo Inst. Techn., Japan)Collaborators: Robert McGreevy (ClarendonLab, Oxford, England), Niels Hessel Andersen(Risö National Lab., Denmark), GunnarJohansson (Dr, Inorganic Chemistry, CTH),Peter Svedlind (Dr, Teknikum, Uppsala Un.)

Research ProjectsA: Structural Glasses and the

Glass TransitionA l : LJght ScatteringOur main interest in glassforming liquids concernsstructural relaxation processes of liquid state mo-tions, and how the freezing out of these motions iscausing the glass transition. The variation in relaxa-tion times, observed during supercooling of liquidswhich fail tocry stallize, is enormous, some 15 ordersof magnitude. To follow processes over such a broadtime range a wide variety of experimental techniquesare needed. We combine different light scatteringmethods; Raman (10-'5-10-i2s), Brillouin (10-'2-10-9s), and photon correlation (10"7-102s). Elect-rical and mechanical spectroscopies are performedby our collaborators over a wide frequency range.

We find that the structural relaxation time vstemperature is independent of the detailed micro-scopic liquid structure-, data from different materialsof the same group of glassforming systems fit thesame curve when using the glass transition tempe-rature as a scaling parameter. However, systematicdifferences occur when changing the intermediaterange connectivity as observed in studies of a widerange of materials from "strong" network glass-formers of covalent bondings via "intermediate"polymeric glasses of entangled networks to "fragile"molecular and ionic glasses held together by weakvan der Waals or Coulomb forces. The experimentaldata have been used förtests of recent theories for theliquid glass transition especially the so called mode-mode-coupling theory recently proposed by prof.


MATERIALS PHYSICS

A. Sjölandei (CTH) et al. and by prof. W. Götze(Miinchen Univ.) et al. The model gives a com-pletely new scenario for glass formation for bothstructural glasses and spin glasses.

A2: Neutron Scattering

The neutron scattering project on glasses aims atinvestigating the dynamics around the glass tran-sition from studies of simple model systems. Asdiscussed above (Al) this is currently a hot topic ofexperimental as well as theoretical interest (mode-coupling-, percolation-, parallel vsconstrained mod-els etc). So far quasi-elastic scattering studies havebeen performed on molecular glasformer, propylenecarbonate and iso-propylbenzene (at ISIS, Oxford).An ionic glassformer Ca-K-N(>3 has been investi-gated by the neutron spin-echo technique (at ILL,Grenoble). The observations support the suggestionof a"new"critical temperature for glass formation inaccordance with mode-coupling predictions.

B: PolymersTheproject concerns studiesof elastic propertiesandmechanical stability in relation to crosslinking,polymerization, polymer mixing etc. The short timedynamics is investigated on the microscopic level torelate the local intrachain flexibility of the polymerbackbone (microscopic viscosity) to the overallmechanical stability (macroscopic elasticity). Frominvestigations of polymers of increasing molecularweight we find that despite changing the macro-icopic behaviour from a fluid to an elastomer byincreasing the chain length, the elastic properties(sound velocity,compressibility,elasticmoduliietc.)are unchanged and seem to depend exclusively onthe local molecular mobility within the polymerchain. In contrast it is found that stabilizing a lowmolecular weight fluid of the same polymer bycrosslinking then the sound velocity increases rap-idlyandmonotonically with thenumber ofcrosslinks.From studies of the structural dynamics we showthat one can define a monomer viscosity whichbehaves like the viscosity of a"fragile" glass former.The classification of glassformers based on a corre-lation of structural fragility with distribution of re-laxation times (non-exponentiality of relaxation pro-cess) relevant for non-polymeric liquids is beingextended to polymers.

C: Fast Ion Conducting GlassesCl: light ScatteringThe increasing interest in vitreous FICS (fast ionconducting solids) is due to favourable properties assolid electrolytes in various technical applications,especially as candidates for microbatteries devel-oped for future 3D integrated circuits. The projectconcerns studies of structure and dynamics of ionconducting glasses, especially the mechanism forion diffusion. Also, two level system (TLS) relaxa-tions at low temperatures (<10K) are investigated.

In vitreous FICS, a remarkable decoupling of themodes of motion of the mobile ions from those of theions, which make up the solid glassy matrix, hasoccurred. This is demonstrated by the decoupling ofthe structural relaxation time of the glassformingmatrix from the relaxation time due to fast iondiffusion, which both have been determined over awide time range from 10-'] s to hundreds of seconds.The decoupled ionic motion can be explained by theexistence in the glass of a sub-network of the dopantsalt (see C2 below). It is this substructure which maysupply a connected network for ionic diffusion.

C2: Neutron Scattering andComputer Simulations

For the neutron scattering program we use the interna-tional facilities at ISIS (Oxford) and ILL (Grenoble).Our diffraction studies show a feature in fast ionconducting glasses which now is much discussed; astrong and anomalous diffraction peak at very low qin the doped (conducting) glass, which is absent inthe undoped (nonconducting) glass. The effect im-plies strong structural correlations in the conductingglass. It may be attributed to an interconnectednetwork of the dopant salt, which is decoupled fromthe glassy matrix and which supplies the conductingpathways for the fast ion transport. Percolation and/or fractal effects of such a structure are currentlyinvestigated. Extensivecomputersimulations, usingthe experimental data as constraints, are also per-formed.

D: Polymeric electrolytesThe research field of polymeric electrolytes is arelatively new area, which is rapidly expanding. Thisis mainly due to applications such as thin film solidstate batteries for electrical vehicles. The light scat-tering studies on ion conducting polymers are aiming at investigating the two most essential properties

72 THE CENTRE FOR

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for a solid electrolyte, namely the mechanical stabil-ity and the ion mobility. This includes structural aswell as dynamical measurements. The project is thebases for a Brite-Euram collaboration program.

So far polyethers (PPO and PEO) of variousmolecular weights complexed with different alkalimetal salts have been investigated. Dramatic changesof the elastic properties are observed with increasingsalt content. It is found that the dissociated salt ionsact as crosslinking centers. As a result the viscosityis dramatically increasing and the ion mobility isdecreasing. We show that it is this effect whichcauses the much discussed drop in the conductivityat large salt content. Another effect influencing theconductivity is ion pairing phenomena. We demon-strate that the amount of free ions, ion-pairs andmultiple aggregates can be quantified by Ramanscattering. It is found that the temperature behaviourof the ion-ion associations are strongly dependent onthe cation valency of the dopant salt. It is contrary towhat existing models suggest.

E: Hlgh-Tc SuperconductorsThe project is directed towards an understanding ofthe basic physical properties of high-Tc supercon-ductors. Our main interest concerns light scattering(Raman and Brillouin) studies of phonons, magnonsand electronic excitations. Many complementaryexperimental techniques (including sol-gel prepa-ration techniques, chemical analysis, neutron- and x-ray diffraction, magnetic and resistivity techniques)are applied to the same samples. The program is partof an EC project (SCIENCE program).

We have been particularly interested in metal ion

and Tl based cuprate superconductors. This offersopportunities for selective studies of the roles of theCuCVplanes, the charge buffer layers (CuO chains,BiO or T1O planes and the CuO chains) and inter-mediate layers for the superconducting properties.Among the most interesting results is that Ramanexperiments give strong indications of a chargetransfer mechanism; e.g. in YBa2Cu3O7-d the CuOchains act as charge reservoirs and provide thesuperconducting planes with holes through a chargetransfer involving lattice vibrations. Any disturbanceof the chains by atomic substitutions (Co, Fe, Al) oroxygen deficiency alters the delicate charge balancebetween the chains and the planes and destroys theefficiency of the charge transfer and thereforedepresses superconductivity.

The superconducting gap is probe by electronicRaman scattering or by phonon self energy effects.In YBa2Cu4Og samples where Y is partly substitutedby Pr it is found that Tc is directly proportional to thesize of the gap.

New batteries are needed for the electricalcar and the polymer battery is a strongcandidate. The figure demonstrates thepresence of "free" solvated ions and aniorvcation pairs in the polymer electrolyteLiBr (PEO)io- The amount of solvated ionsshould be maximised to obtain a largenumber of charge carriers and a high ionicconductivity.

New polymer electrolytes, designedwithin an EC-program, are characterised onthe molecular scale by the MaterialsPhysics Group at Chalmers using laserlight, neutron scattering, and computersimulation techniques.

Free Li

LiBr pair

FreeBr


MATERIALS PHYSICS

Publications

PH.D. DissertationsS. Schantz, Light Scattering in Polymer Electrolytes,

(1990)

Licentiate DissertationsS. Schantz, Raman and Brillouin Scattering Studies of Ion

Conducting Polymers, (1989)

Diploma WorksMats Johansson, PerPedersen: Ramanspridning frän

jonledande polymerer (1989)Nils Addim-Addo, Peter Josefsson: Brillouin spridning

från polymera etectrolyter (1991)Ola Stenlund, Optimization of lens systems (1991)Dennis Engberg, Uppbyggnad av ett Raman microprobe

system (1991)

Reports and articles1. L. Börjesson, U. Dahlborg, W.S.Howells and L.M.

Torell, Evidence of anomalous intermediate- rangeordering in superionic borate glasses from neutrondiffraction., Phys. Rev. B39,3404 (1989).

2. S. Schanlz, Thesis, (1990), Light scattering in polymerelectrolytes.

3. L. Börjesson, M. Elmroth and W. S. Howells, Interme-diate range structural ordering in silver-halide dopedoxide glasses, In "Basic features of the glassy state",Eds. J. Colmenero and A. Alegria (World Scientific,Singapore 1989)p. 93.

4. L. Börjesson, L.M. Torell and W. S. Howells, Brillouinscattering and neutron diffraction in ion-conductingglasses., Philosophical Magazine B59,105, (1989).

5. M. Elmroth, L. Börjesson and L.M Torell, Structuralrelaxation in glassforming liquids, u* "Static andDynamic Properties of Liquids", eds. M. Davidovicand A. K. Soper, (Springer Proc. in Physiscs 40,Springer-Verlag, Berlin 1989) p. 118.

6. L. Börjesson, Low frequency light scattering in lithiumborate glasses; A cross-over from phonons to fractons?Springer Proceedings in Physics, Vol. 37 Eds. D.Richter, A. J. Dianoux, W. Petry and J. Texeira(Springer-Verlag 1989)p.316.

7. L. Börjesson, L.M. Torell and J.R. Stevens, Reply on"Comment on Brillouin scattering study of structuralrelaxation in poly(propylene-glycol) 10000., Polymer30,370,(1989).

8. L.M. Torell and S. Schantz, Light Scattering in PolymerElectrolytes, in Polymer Electrolyte Reviews-2, eds.J Jt. MacCallum and C.A. Vincent, (Elsevier, Londonand New York 1989) p. 1.

9. J. Sandahl, S. Schantz, L. Börjesson, L.M. Torell andJ.R. Stevens, Elastic and Dynamic Properties ofPolymer Electrolytes; a Brillouin Scattering Study ofPoly (Propylene Glycol) - NaCF3CF3 Complexes, J.Chem.Phys.,91,655, (1989)

10. M. Kakihana, J. Sandahl, S. Schantz and L.M. Torell,Optical Spectroscopy in Polymer Electrolytes, Proc.2nd InL Symp. on Polymer Electrolytes, Elsevicr, (1989).

11. M. Kakihana, S. Schantz, B-E Mellander and L.M.Torell, Temperature Dependence of the Charge CarrierGeneration in Polymer Electrolytes; Raman andConductivity Studies of Poly (Propylene Oxide)-L1CIO4 Proc. 2nd Int. Symp. on Polymer Electrolytes,Elsevier, (1989).

12. M. Grimsditch and L. M. Torell, Opposiie ;r. remestructural relaxation behavior in glassformcrs; aBrillouin scattering study of B2O3 and Cao.4 K0.6(NOj)i.4, in Dynamics of disordered materials, eds. D.Richter, A. J. Dianoux, W. Pctry and J. Tcxcira,(Springer Proc. in Physics, 37, Springer 1989) p. 196.

13. M. Kakihana, L. Börjesson, S. Eriksson, P. Svcdlindhand P. NorJing, Raman spectra, superconductivity andstructure of Co-substituted YBa2Cu3O6+d., Phys. Rev.B40,6787, (1989).

14. M. Grimsditch, R. Bhadra and L. M. Torell, Shearwaves through the glass-liquid transformation., Phys.Rev. Lett. 62,2616 (1989).

15. S. Eriksson, L-G. Johansson, L. Börjesson and M.Kakihana, Oxygen content and structural properties ofsome Ba-Cu oxides, PhysicaC 162-164,59-60, (1989).

16. S. Eriksson, L-G. Johansson, L. Börjesson and M.Kakihana, Investigations on oxygen content andordering in Yl(Ba,Sr)2(Cu,Co)307-5 superconductorsby means of wet chemical analysis, x-ray and neutron-diffraction techniques, Phy sica C162-164,73-74, (1989).

17. M. Kakihana, L. Börjesson, S. Eriksson, P. Svedlindhand P. Norling, Synthesis of highly pure YBajCujOy-dsuperconductors using a colloidal processing tech-nique, PhysicaC 162-164,931-932, (1989).

18. M. Kakihana, L. Börjesson, L. M. Torell and S. G.Eriksson, Phonon Raman scattering and structure of Cosubstituted YBa2Cu3O6+5,PhysicaC 162-164,1245-1246,(1989).

74 THE CENTRE FOR

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19. M. Kakihana, L. Börjesson and S. G. Eriksson, Ramanscattering and x-ray diffraction in Ni and Zn substitutedYBa2Cu306+6, Phys. C162-164,1251-1252, (1989).

20. M. KJ;hana, L. Börjesson and S. Eriksson, Theinfluence of oxygen variation on Raman scattering andx-ray diffraction from BaCuO2-5, Phys. C 162-164,1253-1254,(1989).

21. L. Börjesson and W. S. Howells, Intermediate rangestructural ordering in Agl doped supcrionic glasses: Aneutron diffraction study. Solid State Ionics 40/41,702-704, (1990).

22. M. Kakihana, S. Schantz and L.M. Torell, Ramanspectroscopic study of ion-ion Interaction and ItsTemperature Dependence in a PPO-Bascd NaCF3SQ3-Polymcr Electrolyte, J. Chem. Phys., 92,6271, (1990).

23. J. Sandahl.L. Börjesson, J. R. Stevens and L. M. Torell,Elastic and dynamic properties of a poly (propy Icneglycol)-Lithium perchloratc electrolyte: A Brillouinscattering study, Macromolecules (1990) 23,163.

24. M. Kakihana, S. Schantz, J.R. Stevens and L.M. Torell,Dissociated Ions and Ion-ion interactions in Poly(Ethylene Oxide) based NaCFsSQj Complexes., SolidState Ionics, 40/41,641-644, (1990).

25. L.M. Torell, S. Schantz and P. Jacobsson, Raman studyof free volume effects on ion pairs in polymer electro-lytes, Proc. MRS-Socicty Fall Meeting, Boston, (1990).

26. S. H. Chung, K. R. Jeffrey, J. R. Stevens and L.Börjesson, Dynamics of silver ions in (Agl),, (Ag2 O.n8203)1-x glasses: A'°9 Ag nuclear magnetic resonancestudy, Phys. Rev. B41,6154, (1990).

27. M. Kakihana, L. Börjesson, L. M. Torell and S.Eriksson, Raman scattering from metal (Co, Ni andZn)- substituted YBa2Cu3O7-S., Physics and MaterialsScience of High Temperature Superconductors, eds. RKossowsky et al. (Kluwer 1990), p. 581-593.

28. S. Schantz, M. Sandberg and M. Kakihana, NMRstudy of a polypropylene oxide) - NaCF3SQ3 polymerelectrolyte, Solid Stale Ionics 40/41,645-647, (1990).

29. L. M. Torell and S. Schantz, Structural relaxation andchain flexibility in polymeric ion conductors, J. Non-Cryslalline Solids, 131-133, 981-989,(1991).

30. C.A. Angell, L. Monncric and L.M. Torell, Strong andfragile behaviour in liquid polymers, Symp. Mat. Res.Soc., Ed. J. M. O'Reilly, 215,3 (1991).

31. S. Schan x. On the ion association at low salt concen-trations ,n polymer electrolytes; a Raman study ofNaCF3$O3 and LiClO4 dissolved in poly(propyleneoxide), J. Chem. Phys., 94 (1991) 6296.

32. S. Schantz, J. R. Stevens and L. M. Torell, Ion pairingeffects in poly (propylcnc glycol)-salt complexes as afunction of molecular weight and tempcrturc; a Ramanscattering study using NaCF3SO3 and LiClO4.,J. Chem. Phys., 94 (1991) 6862.

33. L. M. Torell, L. Börjesson and M. Elmroth, On thenon-exponentiality vs non-Arrhcnius behaviour of thestructural relaxation in glassforming liquids., J. Phys. C2,207(1990).

34. P. Jacobsson, L. Börjesson and L. M. Torell, When is apolymer a polymer? A light scattering study of crosso-ver from viscous fluidlikc behaviour to chain con-strained dynamics, J. Non-Cryst. Solids, 131-133(1991)104.

35. M. Kakihana, L. Börjesson, S. Eriksson and P.Svcdlindh, Fabrication and characterization of highlypure and homogeneous YBa2Cu3O7-5 from sol-gelderived powders, J. Appl. Phys., 69,867, (1991).

36. M. Kakihana, L. Börjesson and S. G. Eriksson, Phononcharacterization of YBaiCi^Oy-S doped with Al andGa by Raman spectroscopy, Physica B 165 & 166(1990)1245-1246.

37. M. Kakihana, L. Börjesson and S. G. Eriksson, Effectof Sr and Co doping on structure and phonon Ramanspectra of YBa2Cu307-5, Physica B 165&166 (1990)1247-1248

38. J. R. Stevens and P. Jacobsson, A comparison ofacetone and poly (propylcnc glycol) as solvents forlithium inflate and lithium pcrchloratc, Can. J. Chem.,69,1980(1991).

39. L. Börjesson, M. Elmroth and L. M. Torell, Neutronand light scattering study of relaxation dynamics in aglass-forming fragile molecular liquid, Cheni. Phys.149,209(1990).

40. G. A. Niklasson, K. Brantcrvik and L. Börjesson,Conductivity relaxation in silver iodide - silver boralcglasses, J. Non-Cryst. Solids, 131 (1991) 10%.

41. L. Börjesson and W. S. Howells, Incoherentquasiclastic neutron scattering of propylcnc carbonatein the glass instability range, J. Non-Cryst. Solids, 131(1991)53.

42. L. Börjesson, M. Elmrolh and L. M. Torell, A Brillouinscattering study of an extremely "fragMc" molecularglassformcr, J. Non-Cryst. Solids, 131 (1991) 139.


MATERIALS PHYSJCS

43. L. Börjesson and W. S. Howclls, Incoherent Quasiclas-tic Neutron Scattering Study of the Dynamics aroundthe Glass Transition in iso-Propylbcnzcnc, ISIS AnnualReport 1990,(Rutherford-Appleton Laboratory,England, 1990).

44. L. Börjesson and W. S. Howclls, Neutron Diffractionstudy of Supcrionic Glasses, ISIS Annual Report 1990,(Ruthcrford-Appleton Laboratory, England, 1990).

45. S. H. Chung, K. R. Jeffrey, J. R. Stevens and L.Börjesson, Non-Exponential Dynamics of Silver Ionsin Silver Iodide Doped Silver Borate Glasses ThroughNMR, Solid Slate Ionics 40/41,279-283 (1990).

46. M. Kakihana, M. Kall, L. Börjesson, H. Mazaki, H.Yasuoka, P. Berastegui, S. Eriksson and L-G.Johansson, High-Quality Ceramics of YBa2Cu4Ogfrom Citrate Sol-Gel Precursors Sintered at oneAtmosphere Oxygen Pressure, Physica C 173,377-380,(1991).

47. L. Börjesson, The Structure of Salt Doped SuperionicOxide Glasses by Neutron Diffraction, Solid StateIonics, Volume 210, (1991).

48. L. Börjesson and R. McGrccvy, Disorder in Co dopedYBa2Cu3O7, ISIS Experimental Report, (Ruthcrford-Appleton Laboratory, England, 1991).

49. L. Börjesson and R. McGrccvy, Network breaking andstructure modification in alkali silicate glasses, ISISExperimental Report, (Rutherford-Applcton Labora-tory, England, 1991).

50. 1. Albinsson, P. Jacobsson, B-E Mcllandcr, and J. R.Stevens, Ion association effects and ionic conduction inpolyalkalcne modified polydimcthyl siloxancs, SolidState Ionics (in press).

51. L. Börjesson, W.S. Howclls and R. McGrcevy, Fractalaspects of supcrionic glasses from Reverse MomcCarlo simulations, Phil. Mag. 65,261, (1992).

52. M. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuokaand L. Börjesson, Synthesis of cupratc based High-Tcsuperconductors by polymerized complex method,Mat. Res. Soc. Symp. Proc. (in press).

53. L. Börjesson and W.S. Howclls, Quasictastic neutronscattering study of the Ag+ diffusion in a superionicboratc glass, ISIS Ann'ial Report, (Ruthcrfoid-Applcton Laboratory, England, 1991).

54. D. Sidcbottom, R. Bergman, L. Börjesson, and L. M.Torell, Observation of scaling behaviour in the liquid-glass transition range from dynamic light scattering ofpoly(propyleneglycol), Phys. Rev. lett.,68,3587(1992).

55. D. Sidcbottom, R. Bergman, L. Börjesson and L.M.Torell, Photon correlation study of liquid-glass transi-tion in poly (propylcnc glycol), Colloid and Polym.Sci. (in press).

56. P. Jacobsson, G. Pctersen, L. Börjesson and L.M.Torell, Structural relaxation characteristics of super-cooled polymeric liquids. Colloid and Polym. Sci. (inpress).

57. A.K. Hassan, L.M. Torell, L. Börjesson, and H.Doweidar, Structural changes of B2O3 in the liquid-glass transition range ; A Raman scattering study,Phys.Rcv.B, 45,12797 (1992).

58. M Kakihana, S-G. Eriksson, L. Börjesson, L-G.Johansson and C. Ström, Charge transfer and compres-sion effects of isomorphously substitutions in

8, Phys. Rev. B (in press).

59. M. Kakihana, H. Mazuki, H. Yasouka and L.Börjesson, Polymerized Complex Synthesis andintergranular coupling of Bi-Pb-Sr-Ca-Cu-O supercon-ductors, characterized by complex magnetic suscepti-bility, J. Appl. Physics, 71,3904 (1992).

60. M. Kakihana, H. Mazaki, H. Yasouka, L. Börjesson,M. Kail and S. Eriksson, Effect of carrier concentrationon the superconductivity properties of Bi2Sr2Cuj-

4, Physica C (in press).

61. S-G. Eriksson, L-G. Johansson, C.Siröm, L. Börjesson,M. Kall, M. Kakihana, Neutron diffraction and Ramanspcciroscopic studies of Y-123, Physica C 185-189,843,(1991).

62. M. Kall, L. Börjesson, M. Kakihana, C. Ström, L-G.Johansson, S. Eriksson and T. Larsson, Changes in theapical oxygen vibrational frequency and Tc due to Srdoping for Ba in YBa2Cu3C*7-y, T12Ba2CuO6-y andTl2Ba2CaCu2Og-y superconductors, Physica C 185-189,821,(1991).

53. C. Ström, M. Kall, L. G. Johansson, S-G. Eriksson andL. Börjesson. Neutron diffraction studies of Tl-2201,TI-2212 and Y-123 doped with strontium, Physica C!85-189,623,(1991).

64. C. Ström, M. Kall, L. G. Johansjon, S-G. Eriksson andL. Börjesson, Neutron diffraction studies of Tl-2201and TI-2212 doped with lanthanum, Physica C 185-189,625,(1991).

65. L. Börjesson, R. L. McGrccvy and J. Wicks, Thestructure of supcrionic glasses frooi neutron diffractionand Reverse Monte Carlo simulations, J. Phys (Paris),(in press).

76 THE CENTRE FOR

MATERIALS PHYSICS

66. K. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuoka,S. Nishio, Y. Suzuki and L. Börjesson, Structural andphysical properties of rare earth (R) substitutedRBa2Cu(Og-S superconductors, J. Metals and Alloys(in press).

67. L. Börjesson, R. L. McGreevy, L. M. Torell, W.S.Howells, Diffuse neutra scattering studies of disorderin high-Tc superconductors, Physica B 180-181,443,(1992).

68. A.K. Hassan, LM. Torell and L. Börjesson, A Ramanstudy of B2Q3 through the liquid-glass transition range,J. Phys. (Paris) (in press).

69. M. Elmroth, L. Börjesson and L.M. Torell, Observa-tion of a dynamic anomaly in the liquid-glass transfor-mation range by Brillouin scattering, Phys. Rev. Leu.68,79,(1992).

70. G. Petersen, P. Jacobsson and L.M. Torell, A Ramanstudy of ion-polymer and ion-ion interactions in lowmolecular weight polyethcr - LiCT^SQ} complcxe,Electrochimica Acta, 37,1495 (1992).

71. L.M. Torell, P. Jacobsson, D. Sidcbottom and G.Petersen, The importance of ion-polymer crosslinks inpolymer electrolytes, Solid State Ionics 53-56,1037(1992).

72. M. Andersson, L. Börjesson, T. Jarlborg, H. V. Phuongand ö . Rapp, Relations between Cu(l) - 0(4) distanceand Tc in Yi.2xCaxThxBa2Cu3O7-5: Raman scatteringand calculation of the electron phonon interaction,Phys. Rev. B 46,6501, (1992).

73. S-G. Eriksson, C. Ström, L-G. Johansson, L. Börjessonand M. Kakihana, Powder diffraction studies ofsubstituted Y-124, Tl-2201, Tl-2212 and,3aJ4d)2(Nd,Ce)2Cu3Og+8, ISIS, Annual Report 1992(Rutherford-Applelon Lab. England 1992).

74. L.M. Torell, P. Jacobsson and G. Peterson, \ Ramanstudy of ion soivau'on and association in polymerelectrolytes, Accepted for Polym. Advanced Techn.(PAT), "Special Issue on Ion Co ductivity in Polymer"(in press).

75. S. Schantz and L.M. Torell, Evidence of dissolved ionsand ion pain in dilute poly(propyleneoxidc)-saltsolutions, Accepted for Solid State Ionics.

76. P. Bcrastegui, M. Kakihana, H. Mazaki, H. Yasuoka,L-G. Johansson, Eriksson, L. Börjesson, M. Kail, andM. Yoshimura, Polymerized complex synthesis of apure 93-K YzBajCuvOis-g superconductor without theneed of high oxygen pressure and additive catalysts, J.Appl. Phys. (in press).

77. P. Berastegui, L-G. Johansson, M. Kail and L.Börjesson, Structure of Y(Pr)Ba2Cu4Og; A neutrondiffraction study, Physica C (in press).

78. P. Jacobsson, I. Albinsson, B-E. Mcllandcr, and J.R.Stevens, Ion association effects and phase separation inpolypropylene oxide) modified poly(dimcthylsiloxanc)complexcd with triflatc saks. ftalynKsr, 33,2779, (1992).

79. L. Börjesson, L. Van Hong, M. Kall, M. Kakihana, andP. Bcrastegui, The effects of Co substitutions for Cu inYBa2Cu3O6+x on the phonon Raman spectrum, J.Metals & Alloys (in press).

80. L. Ben-Dora, M. Szerera, G. B.'umberg, A. Givana,L.V. Hong and L. Börjesson, Physical Charactcrizatonand vihrational spectroscopy of Bi(Pb) cupratc 2212ceramics prepared by the sol-gel method, Physica C200,418,(1992).

81. N.H. Andersen, J.V. Andersen, L. Börjesson, R.Hadficld, M. Kakihana, R.L. McGrccvy, O.G.Mourilsen and H.F. Pouslen, Structure and conductivityin Co, Fc, Al doped YBa2Cu3O6+x., •>• Mclal andAlloys (in press).

82. J.D. Wicks, R.L. McGrccvy, and L. Börjesson, Thedetermination of the structure of (AgI)x(AgPC»3)i.x bya combination of X-ray and neutron diffraction data, J.Non-Cryst. Solids (in press).

83. M. Kakihana, M. Yashima, M. Yoshimura, M. Kaliand L. Börjesson, Invited review paper: "Applicationof Raman spectroscopy in phase characterization ofadvanced ceramic materials: High-Tc superconductorsand zirconir. ramies", To appear in 'Trends inApplied spectroscopy" (World Scientific).

MATERIALS SCIENCE, 1^93 77

Polymer Technology

Research summaryThe general theme of the research within the depart-ment concerns relations between macromolecularstructure and physical properties, and problems re-lated to production, processing ai.d end-use areinvestigated. We continously work to increase ourresources for and competence on characterization ofpolymer structure, e.g. characterization of differentparameters by GPC, NMR, FTIR and ESCA. Withrelation to physical properties we have specificcompetence in relaxation, both on molecular (NMR,dielectric spectroscopy) and macroscopic (dynamicmechanical spectroscopy) levels. In many cases theresearch is performed in close cooperation withindustry concerning more fundamental aspects ofindustrial relevant problems.The activities can be grouped in three different areas.One concerns synthesis and modification to obtainfunctional polymers. For such polymers the me-chanical properties are not the most important, but itis instead other properties such as optical or electricalthat are of interest. We are studying electricallyconducting polymers, in particular processable sys-tems, e.g. poly(3-alkyl thiophenes) and related poly-mers. The work concerns both aspects related toprocessing (stabilty, degradation, blends) and morefundamental aspects (structure, photoluminescence).We are also involveo in synthesis of liquid crystal-line polymers of the side-chain type, for whichproperties such as ferroelectricity and piezoelectric-ity are of interest. The second area is related tosurface properties of polymers, in particular theeffect of molecular interactions across interfaces andmobility of interphases influences on the propertiesof the whole system. This is studied both in 2-dimensional (laminates, lacquering of polymes) and3-dimensional (polymer blends, composites) sys-tems. The activities on blends and composites aredone as an interdisciplinary cooperation within thematerialsconsortium Interfacial Interactions in Poly-meric Materials. The kno^l "*dge obtained is appliedin a project on recycling of polymers. The third areaconcerns more fundamental studies of problems

related to specialized use of bulk polymers, such aspolyethylene, polypropylene and PVC. One exam-ple is crosslinking by pero\ides or silanes, whichincreases mechanical properties at increased tem-peratures. We are also studying PVC with increasedheat stability, which may lead to decreased u?- ofheat stabilizers containg heavy metals. To obtainpolyethylene with specific properties copolymcrswith functional groups are investigated.

AddressDepartment of Polymer TechnologyChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 3420Fax+46 31 772 3418

StaffSenior membersB. HelgeéP. GatenholmT. HjertbergCKhooF. MaurerS. SchantzR. Shishoo

Graduate studentsL-E. AhlstrandP. BjellheimC. BonnerupT. Chih.- iiH. EklindJ. FelixC. FrennfeltI. GustavssonL-K. KulinN. LjungqvistA. NihlstrandM. PalmlöfM. Rogestedt

fil.dr.docentprof.Ph.Dprof.fil.dr.adj. prof.

fil.kand.civ.ing.civ.ing.civ.ing.civ.ing.civ.ing.civ.ing.civ.ing.fil.kand.civ.ing.civ.ing.civ.ing.civ.ing.

78 THE CENTRE FOR

M. SandbergA. SchmidS. SigurdurssonA. SmedbergK. StrandqvistA. StrålinM. SvenssonL. UlrénM. Wallenius

Technical staffM. BjörklundA. MårtenssonA. RemplingC. SjögrenA. WendelM. Ågren

SecretaryM. HuldénC. Meyer

civ.ingciv.ingciv.ingciv.ingciv.ingciv.ingciv.ingciv.ingciv.ing

Major Instrumentation• GPC for determination of molecular weight

distributions; 2 systems with on-line viscosityand light scattering detectors (solvents: TCB at140°C and THF at 25°C); three smaller roomtemperature systems.Contact person: Lars-Inge Kulin.

• 300 MKz NMR spectrometer, besides solutionmeasurements the instrument is also equippedfor high resolution solid state NMR (CP-MASNMR) at variable temperature.Contact person: Staffan Schantz.

• hi IK spectrometer, transmission and reflectanemeasurements (ATR, RAS, DRIFT); tensiletester for in-line orientation.Contact person: Anders Mårtensson.

• ESCA for surface analysis (shared with dept.of Engineering Metals).Contact person: Anne Wendel.

• DSC (calorimeter) and TGA (thermobalance)for thermal ananlysis.Contact person: Lars-Inge Kulin.

POLYMER TECHNOLOGY

Dynamic mechanical spectrometer for torsionmesurements on solid samples and melts;temperature range -150 - +500°C; frequencyrange 0,001-500 Hz.Contact person: Frans Maurer.

Positron annihilation lifetime spectroscopy forfree volume hole size (1-10 Å) determination.Contact person: Frans Maurer.


A. Polymer synthesisparticipants: B. Helgeé, T. Hjertberg, N. Ljungqvist,M. Sandberg, A. Schmid, M. Wallenius.collaborators: Dept. of Physics and MeasurementTechnology, Linköping University; Research Inst.for Polymers and Textiles, Tsukuba, Japan; LiquidCrystal Group; CTH; Dept.of Organic Chemistry,CTH; Dept. of Chemical Technology, TrondheimUniversityofTechnology;CorporateResearch,NesteOy, Finland.

B. Surface properties of polymersparticipants: C. Bonnerup, H. Eklind, J. Felix, P.Gatenholm, T. Hjertberg, C. Khoo, F. Maurer, A.Nihlstrand, S. Schantz, A. Strålin,collaborators: Dept. of Polymeric Materials, CTH:Polymer Group; Lunds University; Dept. ofMacromolecular Science; Case Western ReserveUniversity, Cleveland, USA; Ecole PolytechniqueMontreal, Montreal, Canada; Neste Chemicals, Fin-land and Belgium; Granges Teknik, Finspång;TetraPak, Lund; Teknisk Utveckling, Volvo,Göteborg;

C. Bulk polymersparticipants: L-E.Ahlstrand, T. Hjertberg, L-I. Kulin,F. Maurer, M. Rogestedt, A. Smedbergcollaborators: Neste Polyeten, Stenungsund, Swe-den; Norsk Hydro, Stenungsund, Sweden, Porsgrund,Norway


POLYMER TECHNOLOGY

Research projects

A. Polymer synthesis

A l : Conducting polymersThe aim of this project is to synthesize stable andprocessible electron conductive polymers, and tostudy applications for these materials. The work isdirected towards different 3-substituted polythio-phenes. Alkyl groups introduce flexiblity, which e.g.allow melt processing. This will, however, also leadto a rapid conductivity loss at increased tempera-tures, thermal undoping. At present, we are synthe-sising polythiophenes with different substituentsand substitution patterns, which shows that it ispossible to combine processiblity and stability inthese polymers. Another part of the project concernsprocessing blends of these polymers and non-con-ductive matrix polymers. The main issues are tolearn the relation between the morphology and theconductivity, and to be able to control the phasestructure via the interactions between the phases.The project is a direct collaboration with the depart-ment of Organic Chemistry, also including closecooperation with Neste Corporate Research, Fin-land, and the department of physics and measure-ment technology, LiTH.

A2: Side chain liquid crystalline polymersThis project on liquid crystalline polymers (LCP) isfocused on ferroelectric LCP:s and is a joint projectbetween the department of PolymerTechnology andthe Liquid Crystal Group at the physics department.Synthesis and characterization of both starting andpolymeric materials 'akes place at the department ofPolymerTechnology, while the evaluation of prop-erties like electro-optic effects, piezo- andpyroelectricity and the like, is carried out at theLiquid Crystal Group.

LCP:s with polysiloxanes as backbone polymershave been synthesized and systems based onpolyacrylates, polymetacrylates and polyesters willalso be made. One objective of the project is tosynthesize self supporting LCP systems with eitherlinear or crosslinked backbone polymerchains. Whenit comes to the mesogeneic groups the aims are tosynthesize units that give rise to high spontaneouspolarization in the chiral smectic C phase.

Chemical and polymeris characterization is car-ried out using NMR, FTIR, DSC (differential scan-ning calorimetry) and SEC (size exclusion chroma-tography).

A3: Polymer gelsA polymergel consists of polymerchains connectedtogether in a network. The crosslinks may be ofeither physical or chemical nature, e.g. crystallinityor covalent bonds, respectively. The aim of thisproject is to study separation properties of porouspolymer gels. Mainly, the work hasconcemed chemi-cally crosslinked networks based on trimetylol-propantrimetacrylate (TRIM). By applying differ-ent comonomers orderivatization different surfaceproeprties are also obtained.

The gels are characterized with respect to theirporosity and the pore size distribution. Apart fromnormal techniques such as mercury intrusion andnitrogen absorption, information about the pore struc-ture is also obtained by studying the separation effectin size exclusion chromatography. Gels modified bychelating groups are evaluated for protein separa-tion. By cooperation with prof. John Ugelstad inTrondheim we are also evaluating monodisperseparticles in SEC.

B. Surface properties

B l : Surface modification of polymeric materialsThe projects concerns surface modifications of pri-marily polyolefin based materials by use of primers,wet chemistry methods and plasma treatment andplasma polymerization. Surface modifications ofpolymers are important for designing specific sur-faces which might be crucial in many applications.The project is directed towards two different appli-cations where the surface properties is an essentialfactor, lacquering of termoplastic elastomers basedon polypropylene and biocompatibility of polymermaterials used in the medical area. Changes in thesurface structure are studied by methods such asESCA, SIMS, FTIR and contact angle measure-ments. The project involves collaboration with theInstitute of Surface Chemistry and Volvo TechnicalDevelopment.

80 THE CENTRE FOR

POLYMER TECHNOLOGY

B2: Laminates between polyethyleneand aluminium

Within this project the effect of molecular interac-tions across the interface on the adhesion is studiedfor laminates between polyethylene and aluminium.Polyethylene is nonpolar and does not contain anygroups that can form specific interactions with thealuminium oxide on the metal surface. The adhesionis therefore very low, but still this assembly is usedin large quantities for packaging. It is a good examplethat properties of two materials can be used in asynergistic way, in this case the barrier properties ofthe aluminium foil and the sealing capacity of thepolymer. In the industrial production of these lami-nates the surface of the polymer is oxidised by hightemperature procssing in order to solve the problemswith adhesion. The oxidation creates a surface layerwith several different groups containing oxygensuch as hydroxyl, carboxylic acid, ketone and alde-hyde, which can form stronger interactions withaluminium. It has not been known to what extentdifferent groups contribute to the increased adhe-sion.

Using FTIR reflection absorption spectroscopy(RAS), we are studying the formation of specificmolecular interactions across the interface betweenthe materials. Systems giving different kind of inter-actions are investigated. To introduce specific groupsat the polymer surface ethylene copolymers withpolar and reactive groups are utilised, and to furthercontrol the interaction the alunrr.ium surface ismodified in different ways. It has been possible tocorrelate the delamination force with the strength ofthe moelcular interactions.

B3: Interfacial interactions in polymer blendsBlending of polymers is an attractive way to obtainnew polymeric materials. The ultimate goal is toachieve an optimal material by combining favour-able properties from the starting materials. As mostpolymer pairs are incompatible, the properties of thecomplex material will be strongly influenced by theinteractions between the phases. The interdiffusionlayers, or interphase, between the phases in a immis-cible polymer blend is considered as a third phaseand has its own characteristic properties. A stronginterphase thus leads to better mechanical propertiesof the blend. We use different experimental andtheoretical methods to characterize the interphase in

polymer blends. This is done by studying thin poly-mer films, 50-800 Å thick, with e.g. FTIR, DMTAand NMR. The mechanical properties can then beexplained by the properties of the interphase and anultimate goal is to achieve custom-made propertiesof a blend by controlling the properties of theinterphase. The project is a part of a material consor-tium, Interfacial Interactions in Polyn.sric Materi-als, consisting of members from Chemical Technol-ogy at Lund Institute of Technology and the depart-ments of Polymer Technology and Polymeric Mate-rials at Chalmers University of Technology. Theco'.sortium hasongoingcooperation with Max PlanckInstitute for Polymer Research, Mainz, Germany,and Dept. of Macromolecular Science, Case West-ern Reserve University, Cleveland, USA.

B4: Adhesion between cellulose and polymersInterfacial interactions and their influence on theadhesion between cellulosic materials and syntheticpolymers are investigated in this project. Commonapplications for these multicomponent systems arefound in the packaging industry and automotiveindustry. The major aim is to elucidate importantadhesion mechanisms and to optimize and evaluatemethods for increasing interfacial interactions. Inorder to fully understand the interaction balance, athorough surface characterization of all componentshas to be carried out. We use ESCA and FTIR fordetermining surface chemistry; static and dynamiccontact angle measurements for studying surfaceenergetics; and inverse gas chromatography to de-termine the dispersive/specific character of the sur-faces. The polymer crystallizr'ion and morphologyat the interface are studied using optical microscopy.Surface properties are related to interfacia' adhesionas measured specifically, using a single-fiber frag-mentation test, which involves tensile testing undermicroscope.

The project is part of the research programme"Cellulose Based Multicomponent Systems" fi-nanced by NUTEK. Collaboration has been estab-lished with École Poly technique, Montreal, Canada;Dept. of Chem. Eng., University of West Virginia,Morgantown, USA; Division of Forestry, Institutefor Surface Chemistry, Stockholm, Sweden, andDept. of Polymeric Materials, CTH.


POLYMER TECHNOLOGY

C: Bulk polymers

C l : Thermal stability of PVCThe thermal stability of PVC is not determined bythe nominal structure but the presence of a fewirregular structures having lower thermal stability.The most important are chlorine on branch carbonand allylic chlorine associated with internal doublebonds. Theircontents are quite low, typically 1 -2 and0-0.2 per 1000 monomer units, respectively. For along time if was not possible to determine thesestructures and thus obtain relations between stabilityand defect structures. Using 13C-NMR we havebeen able to obtain such correlations and also to findout in what way the polymerization conditions influ-ence their formation. The present work is directedtowards methods to avoid the formation of thermallylabile structures, and techniques to minimize theirnegative influence. The latter include introduction ofreactive groups, capable to interfere with the deg-radation process, onto the polymer chains.

C2: Functional polyethylenePolyethylene is the most produced polymer and it isused in a number of everyday applications. In ordertoobtain materials with increased value, polyethyleneproducers try to find speciality qualities. In thisproject we study functional polyethylene, i.e. poly-ethylene containing small amounts of a comonomerwhich gives a special property to the material. Oneexample is comonomers with crosslinkable groupsand we are investigating the mechanism of cross-linking ethylene copolymers containing trimethoxysilane and vinyl groups, respectively. The mecha-nisms are quite different but in both cases thecrosslinking leads to materials with improved prop-erties at increased temperatures. Polyethylene con-taining stabilizing groups is another example. Incontrast to their low molecular weight analogs thesestabilizers should not leak out from the polymer,which allow 'jse under more severe conditions. Onthe other hand the decreased mobility may givereduced reactivity in the stabilizing reactions.

D. Characterization

D l : Molecular mobility in polymeric materialsThe aim of this project is to establish and developsolid state NMR techniques to study relations be-tween molecular mobility and properties of poly-mers. At the department we use a 300 MHz NMRspectrometerfor solid state high resolution CP-MAS(cross polarization magic angle spinning) NMR.With this technique we can study site-specific mo-lecular mobility in the~kHzand -MHz region, usingthe relaxation signals from various nuclei (mainly13C and 1H). In addition, relaxation times can beused to determine the size of heterogeneities in therange ~5-5O0O Å (for studies of multi-phase sys-tems, e.g. polymer blends). The project involvesimplementation of both one- and two-dimensionalpulse techniques as .veil as solid state NMR methodsother than CP-MAS, such as wideline and multipulseNMR spectroscopy.

The application part of the project is done in closecooperation with applied projects both within andoutside the department and mainly in the followingfields; polymer blends (material consortium); elec-tron conducting polymers (Organic chemistry, CTH);ion conducting polymers (Experimental MaterialPhysics, CTH); liquid crystalline polymers (LiquidCrystal Group, Physics, CTH).

82 THE CENTRE FOR

POLYMER TECHNOLOGY

Publications 1990 -1992Ph.D. DissertationsIngrid Gustavsson, Hydrophilic Gels Based on Polyurct-hancUrca, 1990-05-18

Mats Sandberg, Conducting Polymers - Structure andProperties, 1991-03-18

Thami Chihani, Surface Modification of Polymer Materials- The Influence of the Mold Surface, 1992-06-10

Maria Wallenius, Synthesis and Characterization ofFunctional Polymers Based on TrimcthylolpropaneTrimcthacryalteandGIycidyl Mcthacryiate, 1992-10-02

Andrea Schmid, Synthesis and Characterization of S EC-packings Based on Trimcihylolpropanc Trimcthacrylate,1992-10-16

Ucenciate DissertationsLaila Ulrén, The Effect of Different Functional Groups inEthylcne Copolymcrs on the Adhesion to Aluminium,1989-02-09

Magnus Palmlöf, Crosslinking of Ethylcnc VinylsilancCopoiymcrs, 1989-12-15

Kersti Strandqvisl, Computer Simulation of PolymerRcactiors, 1990-02-09

Clacs Frcnnfclt, Adhesion Between Paint and ModifiedPolyolcfins, 1991-05-03

Marie-Louise Lagerstedt-Eidrup, Structure and Propertiesof Poly(3-Alkyl Thiophcnc), 1991-05-30

Margareta Arwidsson, Microstructurc and EnzymaticStability of elhyl-O-(Hydroxycthyl)-Ccllulosc, 1991-06-06

Peter Bicllhcim, Electric Breakdown Strength of AromaticPolymers, 1992-06-09

Chris Bonnerup, Molecular and Topographic Aspects ofAdhesion Between Coatings and Polyolcfin Substrates,1992-10-29

Diploma WorkAsa Eliasson, New Hydrophilic Microfiltration MembranesBased on Polypropylene, 1989

Michael Hansson, The Influence of the content of stabilizeron the degradation of HDPE, 1989

Roger Carlsson and Martin Bcmtsson, Laqucring ofModified Termoplastic Polyolefins, 1989

Per-Ola Nilsson, Crosslinking of Polyamides, 1989

Mats Ganrot, Polymcrdispcrsion for Blending with Con-crete, 1989

Håkan Johansson, Blocked Polyurcthancs as MatrixMaterial in Composites, 1989

Maria Härsjö, Functionalization of Polyurethene-urea,1989

Peter Rydin, IPN of Epoxy and Polyurethane, 1989

Madeleine Nilsson, Synthesis, characterization and Use ofFunctional Polymers with Biocid Activity, 1989

Håkan Kassman, Crosslinking Reactions of Ethylcne VinylSilanc Copolymcrs at Processing Conditions, 1989

Nils Ljungqvist, Synthesis and Polymerization of 3(1,4,7-lrioxo-8,8,8-triphcnyl octyl thiophene), 1990

Margareta Ncméth and Carin Sylvandcr, Simulation ofMold Flow with Rubber, 1990

Kent Hermansson, Polymer Blends with Poly(3-octylthiophcnc), 1990

Maria Andersson and Inger Fransson, Catalysts forCrosslinking of Ethylcnc Vinylsilanc Copolymcrs, 1990

Eva Österberg, Environmental Influence on Stress Crack-ing and Tens )c Strength of Modified Polystyrenes, 1990

Anna Johansson, The Optimum Conditions for a ReactiveCoalcsccnt in ;i Watcrbascd Paint, 1991

Anna Sultan, Methods for Determination of LamellarThickness in Polyethylene, 1991

Anders Frit/, Modification of Epoxy Surfaces with WaterSoluble Functional Polymers, 1991

Peter Fchcr, Modification of Epoxy Surfaces with Fluori-natcd Carboxylic Acids, 1991

Anna Nihlstrand, Characterization of Copolyrncrs withSEC, 1991

Robert Luttu, Characterization of Polycthylcnc/PVCBlends, 1991

Roger Johansson, Stabilization of HDPE Produced with aPhillips Catalyst, M)

Hans Jönsson, Modification of Polymer Surfaces withPolymcrizablc Surfactants, 1991

Wcnche Jensen, Investigation of IPN Based on PUR andWater Soluble Polymers, 1991

Ann Björling, Measurement of Friction on Monofilament,1991


POLYMER TECHNOLOGY

Hans Eklind, Characterization of Electrically ConductingPolymer Blends Containg Poly(3-octylthiophcnc), 1991

Mats Ryrberg, Water Permeability Through Films OfAcrylate Paint and Paint Systems, 1992

Lisbcth Jansson and Jeanette Magnesson, Simulation ofMold Flow with Rubber, 1992

Elisabeth Staaf, Copoplymers of Maleic Anhydride andEthyl Acetate - Structure and Effect on Cellular Plastics,1992

Annika Smedberg, Ethylenc Copolymcrs, 1992

Urban Wecke, A Study of Polymer Fibers with BoundSuperabsorbent Particles, 1992

Madclcne Andersson, Synthesis and Characterization of ALiquid Crystalline Polymer, 1992

Paul Zachrisson, A Study of Adhesion Between DifferentPolyolefins and Ethylcne Copolymers, 1992

Hans Hallberg, Manufacturing of Powder Resin Based onUrea and Formaldehyde, 1992

Åsa Lennartsson and Christin Roscnlöf, Improved Adhe-sion Between LDPE and Aluminium In Extrusion CoatedLaminates, 1992

Jörgen Balogh, Preparation and Characterization of NewMicrolitographic Resists, 1992

Fredrik Andersson, Characterization of Oriented Polymerswith DMTA Techrology, 1992

Paul Koch, Effect of A1CI3 on Thermal Degradation ofPVC, 1992

Reports and articlesJ.F. Rabek, J. Lucki, H. Kcrcszti, T. Hjertbcrg, Q.B. Jun:Catalytic Dehydrochlorination of Solid PVC in the Pres-ence of Aluminium Chloride (Friedcl-Crafts) Catalyst:Studies of the Structure by Spcctroscopical Methods.J. Appl. Polym. Sci., 39,1569 (1990)

L. Ulrén, T. Hjertbcrg, H. Ishida: An FTIR Sudy onIntcrfacial Interactions in Ethylcnc Copolymcrs/AluminiumLaminates in Relation to Adhesion Properties. J. Adhesion,31,117(1990)

T. Hjertbcrg, T. Hargitai, P. Rcinholdsson: A 13C CP-MASNMR Study on Content and Mobility of Double Bonds inPoly(trimethylolpropane trimcthacrylatc). Macromolcculcs,23,3080(1990)

P. Gatcnholm, C. Bonncrup, E. Wallstrom: Wetting andAdhesion of Water-borne Printing Inks on Surface Modi-fied Polyolcfins. J. Adhesion Sci. Techno!., 10,817 (1990)

J. M. Felix, P. Gatcnholm: Evaluation of Surface Treat-ments for Cellulose Fibers and Interfacial Interactions inComposites in: "Controlled Interfaces In CompositeMaterials (ed. H. Ishida), pp. 266 Elscvier Science Publ.,1990

I. Gustavsson, P. Flodin: Synthesis and Characterization ofWaier-Swcllable Polyurcthanc Urea Gels ContainingAllyloxy Groups. I. React. Polym., 12,297 (1990)

L-I. Kulin, P. Flodin: Monosized Polymer Particles in SizeExclusion Chromatography. I. Toluene as Solvent. J. ofChromatogr., 514,1(1990)

K. Jönsson, P. Flodin: Modelling of Urcthanc FormationBr. Polym. 1,23,71(1990)

M. Wallcnius, P. Flodin: Reaction of the Epoxide Groupsof the Copolymer Trimethyiolpropane Trimcthacrylate-Glycidyl Mcthacrylate with Aliphatic Amino Compounds.Br. Polym. J., 23,67 (1990)

T. Hjcrtbcrg, M. Palmlöf, B-Å. Sultan: Chemical Reactionsin Crosslinking of Copolymers of Ethylene andVinyltrimetoxysilanc. J. Appl. Polym. Sci., 42,118* (1991)

M. Palmlöf, T. Hjertberg, B-Å. Sultan: CrosslinkingReactions of Ethylene Vinyl Silane Copolymers.J. Appl. Polym. Sci., 42,1193 (1991)

T. Hjcrtbcrg, R. Dahl: Cooperation between Chemical andPhysical Networks in Crosslinkcd and Plasticized PVC.J. Appl. Polym. Sci., 42,107 (1991)

M. Andersson, P.O. Ekcblad, T. Hjcitbcrg, O. Wenncrstiöm,O. Inganäs: Polylhiophenc with a Free Amino Acid SideChain. Polym. Comm., 32,546 (1991).

G. Gustavsson, O. Inganäs, W.R. Salancck, J. Laakso, M.Loponcn, T. Taka, J.E. östcrholm, J.E. Stubb and T.Hjcrtbcrg: Proccssible Conducting Poly(3-alkyllhiophcncs).in "Conjugated Polymers", Kluwcr Academic Publishers,Dordrecht, 1991, p. 315-60.

B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA andEBA - A Comparison. I. Volatile Decomposition Products.J. Appl. Polym. Sci., 43,1737 (1991)

B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA andEBA - A Comparison. II. Changes in Unsaturation and SideGroup Structure. J. Appl. Polym. Sci., 43,1747 (1991)

B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA andEBA - A Comparison. III. Molccualr Weight Changes.J. Appl. Polym. Sci., 43,1761 (1991)

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E. Jensen, P. Galenholm, S. Nanguneri, L. Mathias: Effectof Chemical Structure of Allyl Ethers on Polymerizationand Properties of Multifunctional Acrylatc SystemsJ. Appl. Polym. Sci., 42,2681 (1991)

J. Felix, P. Galenholm: The Nature of Adhesion in Com-posites of Modified Cellulose Fibers and Polypropylene.J. Appl. Polyin. Sci., 52,689 (1991)

I. Gustavsson, P. Flodin: Synthesis and Characterization ofWater-SwellaWe Polyurcthane Urea Gels ContainingAllyloxy Groups. II. J. Macromol. Sci. - Chem., A27,1477(1991)

I. Gu; 'vsson, P. Flodin: Modification of PolyurethaneUreas Containing Allyloxy Groups. React. Polym., 14,103(1991)

I. Guslavsson, P. Flodin: Functional Polyurcthane UreasContaining Carboxylic Acid Groups. React. Polym., 14,119(1991)

A. Schmid, L-I. Kulin, P. Flodin: Porosity Determination ofPoly(trimcthylolpropane trimethacrylate) gels. Macromol.Chem., 192,1223 (1991)

A. Schmid, P. Flodin :Hydrophilic Gels of Poly(trimcthylol-propane trimethacrylate-co-acrylamide).React. Polym., 15,49 (1991)

K. Jönsson, P. Flodin Vulcanization of Rubber. KineticParameters for SBR and Simulation of Vulcanization in aMold. J. Appl. Polym. Sci., 43 (1991)

B. Helgeé, P. Bjellheim: Electric Breakdown Strength ofAromatic Polymers. IEEE Trans. Electr. Insul., 26,1147(1991)

A. Strålin, T. Hjertberg: A FTIR Study of InterfacialInteractions between Ethylene Copolymcrs and HydraicdAluminium. J. Adhesion Sci. Tcchnol., 6,1233 (1992)

M. Rogcslcdt, T. Hjenberg: Degradation of Poly(vinylchloride) with Incrc cd Thermal Stability. Macromolc-cules.25,6332 (1992)

P.A.M. Stecman, F.HJ. Maurcr An Intcrlaycr Model forthe Complex Dielectric Constant of Composites: AnExtension to Ellipsoidally Shaped Particles.Colloid Polym. Sci., 270,1069 (1992)

P.A.M. Stceman, F.H.J. Maurcr: Dielectric Properties ofPolyamidc-6,6. Polymer, 33,4236 (1992)

M. 'iVelander, F.HJ. Maurer: Decrease in o-Ps Formationin Polymers During Positron Lifetime Measurements.Mater. Sci., Forum Vols. 105-110,1811 (199".)

M. Welander, F.H.J. Maurer: Effect of Sorbed Water andAmide Content on the o-Ps Lifetime in Polyamides. Mater.Sci., Forum Vols. 105-110 1815 (1992)

P.A.M. Steeman, J.F.H. Baetscn, F.HJ. Maurer: Tempera-ture Dependence of the Interfacial Dielectric Loss Processin Glass-bead-filled Polyethylene. Polym. Hng. Sci., 32,352(1992)

G. Scott, H. Ishida, F.HJ. Maurer Rubber-Filler Inter-action Effects on the Solid State Dynamic MechanicalProperties of Polyethylenc/EPDM/Calcium CarbonateComposites. Polymer Composites, 13,237 (1992)

E. Jensen, P, Gatcnholm, C. Sellitti: An ATR-FTIR Studyon Penetration of Resins in Wood.Macromol. Chem., 200,77 (1992)

P. Gatcnholm, J. Kubat, A. Mathiasson: BiodegradableNatural Composites. I. The Effect of Processing on Proper-ties. J. Appl. Polym. Sci., 45,1667 (1992)

P. Gatenholm, J. Felix, C. Klason, J. Kubat: Cellulose-Polymer Composites with Improved Adhesion. Contempo-rary Topics in Polymer Science, Vol. 7, ed. J.C. Salamone,p. (1992)

C. Klason, J. Kubät, »'. Gatcnholir- Wood Fibre-ReinforcedComposites ACS Symposium Scries No. 489, pp. 82 (1992)

A. Schmid, M. Wallenius, P. Flodin: Mechanical Stabilityof Trimmethylolpropanc Trimethacrylate-Based Polymers.J. Appl. Polym. Sci., 45,1995 (1992)

A. Schmid, P. Rodin: Porosity Determination ofPoly(trimethylolpropanetrimethacrylatc-co-methylmclhacrylate) Gels. Makromol. Chem., 193,1579 (1992)

M. Wallcnius, L-I. Kulin, P. Flodin: Synthesis and Charac-terization of Copolymcrs of Trimethylolpropane Trimet-hacrylalc and Glycidyl Mcthacrylalc in Toluene. Pan I.React. Polym., 17,309(1992)

M. Wallenius, P. Flodin: Reactive Carriers for the Immobi-lization of Copper Ions. J. Chromatogr., 604,5 (1992)

B. Hclgec, P. Flodin: Preparation and Properties of BlockCopolyamide Fibres. Polymer, 33,3616 (1992)

M. Andersson, Q. Pei, T. Hjertberg, O. Inganäs, O.Wenncrström and J.E. Östcrholm: Synthesis of SolublePoly(alkylihiophcncs) which arc Thermally Stable in theDoped slate. Synt. Met., accept.

Q. Pci, O. Inganäs, G. Gustavsson, M. Granström, M.Andersson, T. Hjertberg, O. Wcnnerström, J.E. östcrholm,J. Laakso and H. Järvincn: The Routes towards Processiblcand Stable Conducting Poly(thiophcnes). Synt. Met.,accept.


POLYMER TECHNOLOGY

N. Ljungqvist and T. Hjertberg: Compatibility and Phase-Structure Dependence on the Conductivity in Blends ofPoly(3-octyllhiophene). Synt. Met., accept.

S. Schantz and N. Ljungqvist: High-Resolution Solid-State13C NMR Study of POT-PPO Blends. Synt. Met., accept.

A. Strålin, T. Hjertberg: Adhesion between HydratedAluminium and Ethyiene Copolymers Containing MethoxySilanc Groups. J. Appl. Polym. Sci., accept.

A. Strålin, T. Hjertberg: An FTIR Study of Imerfacis*Interactions between Hydraled Aluminium and Pr 'Groups in Ethyiene Copolymers. Surf. Interf. A .-, sis,accept

M. Rogestedt, T. Hjertberg: Structure • ' -' gradation ofCommercial Poly(viny) chloride) Obt ...ed at DifferentTemepratures. Macromolecules, accept.

M. Rogestedt, T. Jonsson, T.Hjertberg: Effect of Polymeri-zation Initiator on Early Colour of Poly(vinyl chloride).J. Appl. Polym. Sci., accept.

T. Chihani P. Bergmark, P. Flodin: Surface Modificationof Ethyiene Copolymers Molded Against Different MoldSurfaces 1. Surface Enrichment by Functional Groups.J. Adhesion Sci. Technol., accept.

T. Chihani, T. Hjertberg: A XPS Study of DifferentPolyvinyl Alcohol Films Surface Composition.J. Appl. Polym. Sci., accept.

T. Chihani, P. Bergmark, P. Flodin, T. Hjertberg: SurfaceProperties of an Anhydride-epoxy Resin Cured AgainstDifferent Mold Surfaces. J. Adhesion Sci. Technol., accept.

T. Chihani, P. Flodin, T. Hjertberg: Surface Modification ofEpoxy Copolymcrs with Different Perfluoroacids.J. Adhesion Sci. Technol., accept.

T. Chihani, P. Flodin, T. Hjcrtbcrg: Modification of EpoxySurfaces with Different Polyvinylalcohol Polymers. J.Apr' ''j'.ym. Sci., accept.

. lix, P. Gatenholm: Characterization of Ccllulosic• Yocrs Using Inverse Gas Chromatography.Nordic Pulp & Paper J., accept.

J. Felix, P. Gatenholm, H. Schreiber: Controlled Interac-tions in Cellulose-Polymer Composites. I. Effect onMechanical Properties. Polym. Eng. Sci., accept.

P. Gatenholm, H. Bertilsson, A. Mathiasson: The Effect ofIntcrphasc on Dispersion of Cellulose Fibers in Plastics.J. Appl. Polym. Sci., accept.

C. Bonncrup, P. Gatenholm: Physical Modification of PP/EPDM Surfaces I. Determination of Surface Compositionans Surface Order by FTIR-ATR. J. Polym.Sci. Phys. Ed.,accept

C. Bonncrup, P. Gatenholm: The Effect of SurfaceEnergetics and Molecular Intcrdiffusion on Adhesion inMulticomponcni Polymer Systems. J. Adhesion Sci.Tcchnol., accept.

P. Bjcllheim, B. Hclgeé: Aromatic Polyimidcs: Synthesis,Characterization and Evaluation of Electric Strength. J.Appl. Polm. Sci.,

86 THE CENTRE FOR

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Research SummaryAtpresentourresearch activities are centered aroundthe following topics.

A: Mechanical properties, viscoelasticity andageing.

B: Physical properties of polymeric systems.C: Rheology and processing.D: Recycling of polymers.

In the following, our activities in these areas will becommented on briefly.

AddressChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone-^46 31 772 1310Fax+46 31 772 1313

StaffSenior staffCarlKlason

Josef KubätHans Bertilsson

Rodney Rychwalski

Per BengtssonJohan BeckerAnders MathiassonJan Åbom

TecMcaJ staffKristina ThomebyUlla Engström

Graduate studentsMohsen SafariReza EbrahimzadehMats DelinHenrik LarssonLena Kvist

Professor,Head of DepartmentProfessor emeritusPh.D., lecturer,Deputy HeadofDepartmentPh.D., guest researcher,lecturerPh.D.Ph.D.Ph.D.Senior research assistant

SecretarySecretary (part time)

Anders PerssonThomas Rundquist1

Hans Walter*Bjarne Moursund2

JanWahlbergiIon Postoaca1

1 In collaboration with Lund Institute of Technology2 In collaboration with Norsk Hydro and NordiskIndustriforskerkomité

Major Instrumentation• Tensile testing machine• Rheometers (rotational and capillary for melts,

hot-melts and liquids)• High precision relaxometers• Equipment for stress dilatometry• Instrumentation for advanced dynamic-me-

chanical spectroscopy• Dielectric characterization (time domain

spectrometer)• Equipment for thermal analysis (DSC, TGA)• Equipment for measuring interfacial tension of

polymer blends in molten state• SEM equipment with tensile stage• Equipment for measuring noise and frequency

analysis• Compunding machines (Brabender kneaders,

Buss kneader, twin-screw extruder)• Two single screw extruders• Two injection moulding-machines• Moulding press

Financial Support1. Swedish National Board for Industrial Devel-

opment, NUTEK2. Swedish Research Council for Engineering

Sciences, TFR3. Swedish Council for Planning and Coordina-

tion of Research, FRN4. The Swedish Natural Science Research Council,

NFR


POLYMERIC MATERIALS

5. Carl Trygger Scientific Research Foundation6. Chalmers Research Foundation7. Jacob Wallenberg Research Foundation8. Axel och Margaret AX:son Johnson Foundation


A: Mechanical Properties, Visco-elasticity and Ageing In Polymers

Participants: C Klason, J Kubåt, H Bertilsson and RW Rychwalski.Collaborators: J M Hutchinson, Aberdeen Univer-sity, F Maurer, Department of Polymer Technology,CTH, S Andersson, Chalmers Industriteknik, ZSobotka, Czechoslovakia Academy of Sciences,Institute of Mathematics, Prague, S Uggla, Depart-ment of Numerical Analysis, CTH, Ch Högfors,Centre for Biomechanics, CTH, B Edberg, Depart-ment of Textile Technology, CTH.

B: Physical Propertiesof Polymeric Systems

Participants: C Klason, J Kubåt, H Bertilsson and RW Rychwalski.Collaborators: T Kitano, Research Institute of Poly-mers and Textiles, Tsukuba, Japan, O Quadrat,Institute of Macromolecular Chemistry, Prague,Czech Republic, P Säha, Technical University ofBrno, Zlih, Czech Republic, A Ponomarenko, Insti-tute for Synthetic Polymeric Matenals, RussianAcademy of Sciences,Moscow, Russia, Th Hjertberg,F Maurer, P Gatenholm, Department of PolymerTechnology, CTH.

C: Rheoiogy and Polymer ProcessingParticipants: C Klason, J Kubåt and H BertilssonCollaborators: T Kitano, Research Institute of Poly-mers and Textiles, Tsukuba, Japan, P Säha, Techni-cal University of Brno, Zh'n, Czech Republic, V VJinescu, Polytechnic Institute, Bucharest, Romania,P Gatenholm, Departmeiit of Polymer Technology,CTH, B Edberg, Deptartment of Textile Technol-ogy, CTH, B Wesslén, Department of ChemicalEngineering, University of Lund and J-E Ståhl,Department of Production and Materials Engineer-ing, University of Lund.

D: Recycling of PolymersParticipants: C Klason and H BertilssonCollaborators: Chemical Environmental Science,CTH, Department of Polymeric Materials, CTH,Plastics and Rubber Institute (PGI), Gothenburg,and Swedish National Testing and Research In-stitute (SP), Borås.

Research projectsA l : Volume Flow and Physical Ageing

of Solid PolymersIt is well-known that glasses ana semicrystallinepolymers age physically and the ageing is accompa-nied by a change of properties (dimensional stability,rheological properties, oensification, etc.). A slowdensification from non-equilibrium toequilibrium isobserved also in transient flow. The possible simi-larity of physical ageing and transient flow withregard to the accompanying, evolving volume is thestarting point of a study on strain induced physicalageing.

The volumetric analysis is carried out experimen-tally and theoretically. A liquid stress dilatometer ofhigher stability (< 2.5 x 1(H ml/h) and non-disturb-ing clip-on inductive extensometers have been built.Great attention is given to the elimination of tem-perature effects and the indentation of extensometer' smeasuring piobes. The developed experimental tech -nique enables measurements of very small volumechanges even in the demanding condition of stressrelaxation, on soft-rubbery specimens, over manydecades of time (measured volume changes aretypically 0.3-0.4 mmtydecade of time, or change ofdiameter is approx. 0.5 micron/decade of time).

Theoretical analyses within the framework oflinear viscoelasticity and free volume theory areused. These include:• calculation of volume strain using the differen-

tial representation of linear viscoelasticity withspecial interest given to strain rate effects

• calculation of volume strain proceeding from aspectrum of volume retardation times

• calculation of volume strain using the WLF/Kovacs theories with the shifting single relaxa-tion time

• calculation of volume strain using the KAHR-model with the shifting discrete spectrum ofrelaxation times

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• analyses of shift factors• predictions from stretched exponential formula.

A range of measurements and predictions are atpresent carried out in the department of PolymericMaterials, CTH, and in the department of PolymerTechnology, KTH. It has been measured at smallstrains for low density polyethylene that volume vs.time behaviour in stress relaxation is similar to thestress decay. On the other hand a comparison ofvolume-stress plots measured in straining at a %,on-stantrateof strain and in stress relaxation are dissimi-lar, and are also different for linear and branchedLDPE. Simultaneously the time dependence ofcontractional ratio has been measured. It has beenestablished from volumetric studies in creep of PCand PMMA that a ratio of transverse and longitudi-nal strain rates is more indicative for volume flowprocesses in solid polymers than the contractionalratio (Poisson's ratio). The volumetric measure-ments are carried out in parallel with rheologicalcharacterization.

A long-term cooperation with the Department ofEngineering, Aberdeen University (UK), Institute ofMathematics, Czechoslovakian Academy of Sci-ences (Czech Republic), Department of NumericalAnalysis, CTH, has been established. Implementa-tion of Positron Annihilation Life-time Spectroscopy(PALS) for structural observations is here of interestand this is planned in collaboration with the Depart-ment of Polymer Technology, CTH.

A2: Time Dependent Mechanical Propertiesof Advanced Textile Fibres

Textile materials and products for advanced engi-neering applications represent a steadily growingsector of the textile industry. The lack of availableinformation on the viscoelastic behaviour is particu-larly pungent with the new generation of fibres usedin engineering applications. The present project willfocus on such problems and will include creep andrelaxation characterization of a number of advancedfibre materials used in industrial textile products.The data will be supplemented by dynamic-me-chanical measurements. Special interest will be de-voted to the both scientifically and technically im-portant phenomenon of accelerated flow under con-ditions of periodically changing humidity of thesurrounding atmosphere. The result will be analyzedin terms of established theoretical models. Fibrousspecimens, representing an extreme case of molecu-

lar orientation, appear to be highly interesting fromthis point of view. The planned project activities aimat reducing present uncertainties about the timedependent behaviour of the fibres in question.

Bl: Polymer Blends: Whiskeis In ImmisciblePolymer Blends

Polymer alloys from incompatible polymer combi-nations are compatibilized by adding small amountsof block- or graft copolymers. The compatibilizingeffect from fillers and fibers have been reported inliterature but so far have not been systematicallystudied or understood. The basic idea is that two (ormore) polymers, should compete with each other tocover the surface of the filler and thus the morphol-ogy achieved during the compounding should bestabilized at the same time as the filler and not theweak polymer-polymer interfaces are transferingthe mechanical stresses. The degree of dispersionnecessary to achieve interesting mechanical proper-ties lies in the range of 1 m or less for the diameterof the dispersed phase. The size of the filler particlesmust be of the same magnitude which excludes theuse of common fibres. The use of whiskers is morepromising since they have diameters of the appropri-ate size and still an attractive aspect ratio giving ahigh surface to volume ratio. The use of whiskers iscommonly restricted by high cost but we have foundan aluminum borate whisker which can be producedat the price of carbon fibres.

A range of incompatible polymer pairs has beensuccessfully studied using whiskers (in amounts of 5-15 vol.%) as compatibilizer. An illustrative exam-ple is presented in figures 1 and 2 showing a SAN/PA6 70/30 blend. The volume content of whiskersequal 10 % drastically changes the crack propaga-tion from following-the-weak-polymer-polymer-interfaces to proceeding right-through-the-material.As expected the strength and stiffness was substan-tially improved by the whiskers but more interestingis that the elongation at break also increased. Thiswas explained by a closer view on the morphology.In fig. 3, showing the same blend as in fig. 2, the SANmatrix has been removed by a solvent and theremaining minority polymer and the whiskers forma continuous phase. This interesting morphologywas obtained by first compounding the whiskerswith SAN, and then introducing PA6 in a secondstep. The interaction PA6 versus whiskers is muchstronger than SAN versus whiskers. We have found


POLYMERIC MATERIALS

Fig 1: Fracture area of SAN/PAG 70/30 blend.

Fig 3: The same blend as in fig 2 where the SANmatrix has been removed by dissolving.

that the morphology isdetermined by the differencesin polymer-whisker interaction and by the viscosityratio of the polymers. The polymer-whisker interac-tions have so far been qualitatively characterized bydynamic mechanical analyses but a more quantita-tive characterization using inverse gas chromatogra-phy is running at present.

So far only completely immiscible pairs havebeen considered. For polymer pairsshowing smaller,but yet positive interaction parameters, still moreinteresting phenomena are to be expected. Accord-ing to results of prof. Lipatov, Ukraina, the polymer-polymer interaction parameter can be substantiallyreduced, and become even negative, at the surface ofa filler to which both polymers exhibit some interac-tion. This opens up the possibility for a third misciblepolymer phase in a system of immiscible polymersand the whiskers.

Fig 2: Fracture area of SAN/PAG 70/30 blend with10% by volume of whiskers.

Among important areas for thi s compatibilizationtechnique is the alloying of high temperature resist-ant polymers where blocks and grafts cannot be useddue to thermally weak block links. Blends of liquidcrystalline polymers with common engineering poly-mers suffer from inadequatecompatibilization routesand weak interfaces. Compatibilizaticn with whisk-ers will open up new possibilities in this context.Morphology control per se is important in caseswhere continuity of a dispersed minority phase isdesired. We have recently obtained promising re-sults concerning the dispersion of an electricallyconductive polymer in matrices of common engi-neering polymers.

The activities concerning the whiskers in poly-mer blends are parts of the NIWNUTEK consor-tium programme "Interfacial interactions in poly-meric materials".

B2: Noise, Relaxation and Ageing Phenomenain Polymeric Systems

There is a growing interest for measurements of thespontaneousconductancefluctuations(conductancenoise) in technological materials with some degreeof microscopic disorder, such as polymers and high-Tc superconductors. This is because measurementsof conductance noise represent one of the mostpowerful methods of studying the influence of mi-croscopic disorder in materials. The reason for this iswell-known; the measured conductance noise am-plitude is the sum of cross-terms, originating fromdifferent sub volumes of the material, and theseterms are proportional to the square of the localcurrent density.

90 THE CENTRE FOR

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Similarly, measurements of noise phenomenaduring stress relaxation and physical ageing of poly-mers can be expected to be a far moie powerfulmethod of investigating the underlying mechanismsthan the measurement of the bulk behaviour. Thesame applies toother typesof time dependent behav-iours of solid polymers where, basically, the mecha-nisms responsible for the macroscopic behaviourremain largely unexplained. This idea is the startingpoint of the present project. Since common polymersdo not possess a sufficient degree of conductivity inorder to allow the fluctuations of the charge carriersto be determined directly, the systems to be investi-gated have to consist of polymer based compositescontaining suitably selected conducting particles.

This project is carried out in collaboration withthe Department of Solid State Physics at UppsalaUniversity.

33: Dielectric Properties of Polymers andPolymer Based Composites

ft s project consists of two parts, all relating to theV< lectric behaviour of polymers and polymer based

a mposites. The first part aims at quantifying af irticutor similarity between the time-domain di-lectric behaviour of polymers and the kinetics of

stress relaxation, physical ageing, and similar proc-esses.

The second part is focused on polymeric composi-tes with high valuesof dielectric constant for absorp-tion of high frequency electromagnetic radiation.

C l : Rheology of Filled PolymersThe objective of this research project is to create abroadened basic understanding of the Theologicalbehaviour of filled engineering plastics and theirtime dependent mechanical properties. The pro-cessability of filled polymers, and hence the proper-ties of the finished products, is closely related to theTheological properties of tne polymeric materials inthe molten state, and to the properties of the interfacebetween the filler and the matrix. Studies of thecompatibiltyofmixedplasticscontainingmicrofibrilsof cellulose is part of this project.

Another field of interest is carbon black filledpolymers and the influence of processing on theelectrical properties. These polymers are of specialinterest in heating devices due to a positive thermalcoefficient of resistivity (PTC-effect) under certain

conditions. A method of studying the noise in con-ducting polymers has been developed. The basicidea behind the noise measurements is the notion thatspectral analysis of the noise may provide usefulphysical information about the underlying molecu-lar mechanisms. The object of the current researchproject is to study the temperature dependence of theresistivity of conducting polymers, and how the typeof filler and its content will influence the electricaland dielectrical properties of the composite. Also,the noise method will be used to study flow phenom •ena and structure of polymer solutions and gels. Theproblems under study relate not only to flow proper-ties of solutions, but also to melt flow instabilities,rheology of melts and flow behaviour and propertiesof reinforced polymers.

The rheology and processing of thermoplasticshas earlier been experimentally studied in coopera-tion with Dr. P Sdha at the Faculty of Technology,BmoUniversity in Czech Republic. Also in thisarea,the frequency analysis (noise method) has been usedto study melt flow instabilities, and a flow visualiza-tion method has been developed to study the meltprocess in a single screw extruder. Recently a col-laboration in this area has been established with Prof.Jinescu of the Polytechnic Institute in Bucarest,Rumania. The project deals with simulation of flowin mixers (in single screw extruders).

Polymer-polymer interfacial tension is a criticalparameter determining processing and performancecharacteristics of multicomponent polymeric sys-tems. A recently developed method of the ImbeddedFibre Retraction (IFR) allows the evaluation of theinterfacial tension between high polymers at el-evated temperatures. IFR is based on the analysis ofthe transitional shapeevolution of a short fibre of onemateria! imbedded in a matrix of a second.

The uniqueness of the method is related to itsability to provide a value for the interfacial tensionbetween high-viscosity materials over a relativelyshort period of required experimentation. This projectis in collaboration with the Dow Chemical Com-pany, Midland, Michigan, USA.

Mould design is critical in all processing tech-niques. The object of this project is to use porousmetal in order to improve the venting of the mouldduring filling and to improve the tempering of themoulds using a gas cooling technique. This project issupported by Perstorp AB.


POLYMERIC MATERIALS

D l : Recycling of PolymersThis project started during the autumn -92 with theaim to establish an interdisciplinary consortium inthe area based on the following groups:- Department of Chemical Environmental

Science, CTH- Department of Polymer Technology, CTH- Department of Polymeric Materials, CTH- Plastics and Rubber Institute (PGI), Göteborg- Swedish National Testing and Research

Institute (SP), Borås

Two activities within the programme are carried outat the Department of Polymeric Materials; recyclirgof engineering thermoplastics and composites basedon paper and plastics waste. The idea behind theformer mentioned activity is to implement knowl-edge and techniques from polymer alloying in theupgrading of recycled engineering thermoplastics.The prices of engineering thermoplastics are 4 - 5times (or more) higher than those of commoditymaterials and thus there are possibilities to end upwith attractive prices for the recycled materials evenwith necessary allowances for upgrading processes.The conventional route for material recycling hasbeen, so far, to recycle a specific thermoplastic afterupgrading, to the same thermoplastic again, evensometimes to the same product. In the future, whenstreams of different engineering thermoplastics forrecycling are expected to appear, the technology ofmixing them properly in order to achieve the bestpositive synergistic effects will play a great role. Thematerials of interest so far are ABS, ASA, SAN, PC,PBT, PET, PA and PP. If recycled SAN is mixedwith recycled PC, for example, very good propertiescan be found even at moderate levels of PC. Verysmall amounts of PCL has been found to be apowerful additive for morphology control. SinceSAN is the matrix in ABS and ASA the same idea isused for them, giving high impact strength in usedABS, where the impact modifier is destroyed byageing. Concerning polyesters like PET and PBT,transesterification processes during compoundingshall be studied in order to obtain desired morphol-ogy (property control in blends with PC and PA, forexample).

The cooperation with other involved researchdepartments is important. The Department of Che-mical Environmental Science is in a position toevaluate our ideas of recycling versus alternative

routes for recycling. SP (Boras) is working withproblems concerning specifications for the recycledmaterials and, they are interested in finding thesynergistic effects from reprocessing and ageing.

The other activity within the recycling programmeat our department concerns composites based onpaper and plastic waste. The aim of this part is tocreate structural composites with good mechanicalproperties and good long-term exposure propertiesfrom recycled materials containing polymer andcellulose fibers. A prerequisite for the project isthrough knowledge of the origin of the waste, itscomposition and possible treatment. The surfaceproperties of the fiber and its possibility to interactwith different functional groups in the polymer is acrucial factor, both for dispersion of the fibers in themelt during processing and the interfacial strengthbetween the two components. Another factor thatwill be investigated is reprocessing. To improvedispersion and adhesion, compatibilizers and treat-ments will be selected for fibre treatment prior tocompounding o- in a one-step process. The obtainedcomposite materials will be evaluated with respect tomechanical properties, environmental ageing as wellas recyclability. Studies of the rheology and flowproperties as well as optimization of the processingparameters are other areas of interest.

92 THE CENTRE FOR

POLYMERIC MATERIALS

PublicationsPhJ>. Dissertations 1988 -1992Björn Franzén, "Mechanical properties of some polymeric

alloys and composites", 1989Maria Welander, "Ageing and viscoelasticity of filled

HDPE", 1989Johan Becker, "Unstable flow of molten polymers", 1992Per Bengtsson, "Electrical properties of carbon black-filled

polymers", 1992Anders Mathiasson, "Cellulosic fillers in thermoplastics",

1992

Reports and articles1. BengtssonP,Klason C, KubälJam!McQueenDH:

Electrical Noise Characteristics of Carbon Black-FilledChloroprene, Rubber Journal of Physics D, 22 (1989)1736

2. Bertilsson H.Franzén B and KubétJ: Creep andVolume Dilatation in PC/PBT Blends, Plastics andRubber Processing and Applications, 11 (1989) 167

3. Welander M: Effect of high stress on the ageing beha-viour of high density polyethylene, Polymer, 31 (1990) 64

4. Bengtsson P, Klason C, Kubät J and McQueen DH:Positive temperature coefficient effects in carbonblack-filled chloroprene rubber, Plastics and RubberProcessing and Applications, 15 (1991) 257

5. Becker J, Bengtsson P, Klason C, Kubäl J and Sana P:Pressure oscillations during capillary extrusion of highdensity polyethylene, Inter Polymer Processing, VI(1991): 4,318

6. Becker J, Klason C, Kubät J and Sana P: Meltinginstability phenomena in polymer extrusion, Plasticsand Rubber Processing and Applications, 14 (1990) 77

7. Becker J, Klason C.KubatJ and Sana P: Melt strengthand rupture frequency in LDPE film blowing, Plasticsand Rubber Processing and Applications. 14 (1990) 23

8. Becker J, Klason C, Kubät J and Sana P: Frequencyanalysis of pressure fluctuations in a single-screwextruder, Inter Polyrer Processing, VI (1991): 4,326

9. Bertilsson H ami kindberg K: Morphology of polya-mide 6 - polybuladiene multiblock copolymers, J MatSci, 26 (1991) 4383

10. Lindberg K, Johansson M and Bertilsson H: Effects ofthe addition of a multiblock copolymer to an incompa-tible blend, Plastics and Rubber Processing and Appli-cations, 14 (1990) 195

11. Kitano T, Klason C and Kubät J: Flow properties ofliquid crystalline polymer and its fibre filled systemmelt, Reports on Progress in Polymer Physics in Japan,XXXII (1989) 71

12. Lindberg K A H, Vescly D and Bertilsson H: Electronbeam damage of some chlorine containing polymersand PVC blends, J Mat Sci, 24 (1989) 2825

13. Klason C, Kubät J and Quadrat O: Excess thermalnoise generated by the capillary flow of alkalinizedlatex dispersions carrying carboxyl groups, Rhcol Acta,30(1991)180

14. Klason C, Kubät J and Quadrat O: Electrical noisegenerated during the capillary flow of polyethyleneoxide) solutions. The influence of the solvent power,Polymer, 33 (1992): 7,1464

15. Kubät D G and Klason C: Stress relaxation in wood(Scots pine veneer) 2. Quantitative cor parison withthe prediction of a cooperative flow model, J Mat Sci,26(1991)5261

16. Klason C, Kubät J and Gatenholm P: Wood fiber-reinforced composites, ASC Symposium Series 489,Viscoelasticity of Biomaterials, Eds. Glaser, Hata-keyama, American Chemical Society, Washington DC,1992, p. 82

17. Brostow W, Cook R and Kubät J: Molecular dynamicsand Monte Carlo simulations of polymeric materials:Chain relaxation dynamics, Integral Methods in Scienceand Engineering -90, Eds.: Haji-Shcikh, Corduneanu,Fry, Huang and Payne, Hemisphere Publ. Co.,Washington DC, 1991, p. 24

18. Bcrtilsson H, Franzén B, Klason C. Kubät J andKitano T: The influence of processing on fibre orienta-tion and creep in short carbon-fibre reinforced lowdensity polyethylene and polycarbonate, PolymerComposites, 13 (1992): 2, p. 121

19. Gatenholm P, Klason C and Kubät J: Cellulose-polymercomposites with improved properties, Polymer Science,7 in Contemporary Physics, Ed. J Salomonc, PlenumPubl. J992

20. Scrtilsson H, Kubät D G, Kubät J and Uggla S: Asimplified cooperative model of stress relaxation andother consolidation processes in solids, Rhcol Acta, 31(1992) 390

21. Kubat D G, Berulsson H, Kubät J and Uggla S: Amodified cooperative model of relaxation and ageingkinetics, J Phys: Condensed Matter, 4 (1992) 7041


POLYMERIC MATERIALS

22. Klason C, Kubat J and Quadrat O: Electrical noise andstreaming potential generated during capillary flow ofpoly(ethulcne oxide) solutions, J AppI Phys, 72 (1992)3219

23. Kubdt M J, Jansson J F, Delin M. Kubai J. RychwalskiR W and Uggla S: Some phcnomcnological relaxationrate equations based on B-E similar kinetics, J AppIPhys, 72 (1992) dec.

24. Kuzel R, Krivka I, Stefan O, Kubåt J. Hrovat M, RafajaD, Pesicka J, Prokes J and Broukal J: Problems withresistive paste preparation, J Microelectronics, Elec-tronic Components and Materials, 21 (1991)4,195

25. Bertilsson H, Delin M, Kubät J, Kubåt M J, RychwalskiR W and Sobotka Z: Modelling volume strain duringflow of solid polymers, Theoretical and AppliedRhcology, Eds.: Moldcnaers P, Keunings R, Proceed-ings Xlth International Congress on Rheology, Brus-sels, Elsevier Sci Pubi B.V., 1992, p. 793

26. Kuzel E, Kubät J, Keivka I, Prokes J, Klason C andStefan O: Heterogeneous systems based on preciousmetal powders and polymers, Proc. EMRS 1992Spring Meeting, International Conference on Electro-nic Materials, Strasbourg, France, 1992, p. C-VII/P4

27. Kubåt J, Kuzel R, Krivka I, Bengtsson P, Prokes J andStefan O: New conductive polymeric systems, Proc.EMRS 1992 Spring Meeting, International Conferenceon Electronic Materials, Strasbourg, France, June 1992,p. E-IV/P6

28. Blonski S, Brostow W and Kubåt J: Computer simula-tion of stress relaxation, Amer Chcm Soc Polym Paper,33(1992): 1,625

29. Klason C, Kubät J and Quadrat O: Flow properties andelectrical noise generated during capillary flow ofNewtonian liquids, Theoretical and Applied Rheology,Eds.: Moldcnaers P, Keunings R, Proceedings XlthInternational Congress on Rhcology, Brussels, ElscvierSciPublB.V.,1992,p.481

30. Klason C, Kubät J and Quadrat O: Relation betweenelectrical noise generated during capillary flow ofaqueous poly/ethylene oxide solutions and streamingpotential, Proceedings of Noise in Physical Systemsand 1/f Fluctuations, Kyoto, Japan, Eds. T Musha, SSato, M Yamamoto, Ohmsha Ltd. 1991, p. 141

31. Gatenholm P, Kubät J, Mathiasson A: Biodegradablenatural composites. I. Processing and properties, J AppIPolym Sci, 45 (1992) 1667

32. Klason C, Kubåt J and Skov H R: Hydrolytic treatmentof plastics waste containing paper in "Plastics Materi-als Recycling", Ed. E P La Mantia, Chcm Tec Publ.,Toronto, Canada, 1992

33. Kuzel R, Kubät J, Krivka I, Prokes J and Nozar P: Newpolymeric composites, Proceedings of 12th GeneralConference of the Condensed Matter Division, Prague,Czechoslovakia, 1992, p. 105

34. Krivka I, Stefan O, Kuzel R, Kubäl J and Rafaja D:Glass composites - Hetcrogcnous systems, Proceedingsof 12th General Conference of the Condensed MatterDivision, Prage, Czechoslovakia, 1992, p. 141

35. Kubat J, Prokes J, Kuzel R, Krivka I and Stefan O:Diclcctric properties of polymeric composites, Procee-dings of 12th General Conference of the CondensedMatter Divison, Prague, Czechoslovakia, 1992, p. 105

36. Prokes J, Kubat J, Kuzcl R, Krivka I and Stefan O:Frequency measurements on some polymeric compos-ites, Proceedings of 34th IUPAC International Sympo-sium on Macromolcculcs, Prague, Czechoslovakia,1992, p. 4-P42

37. Kubät J, Bengtsson P, Krivka I, Prokes J, Kuzcl R andStefan O: Carbon black-filled polyethylene andchloroprcnc rubber, Proceedings of 34th IUPACInternational Symposium on Macromolcculcs, Prague,Czechoslovakia, 1992, p. 4-P43

38. Kuzei R, Kubat J, Krivka I, Klason C, Stefan O andProkes J: Polymeric composites filled with preciousmetal conductive powders, Proceedings of 34thIUPAC International Symposium on Macromoleculcs,Prague, Czechoslovakia, 1992, p. 5-P92

39. Kuzcl R, Kubät J, Prokes J, Krivka I, Klason C andStefan O. Polymeric materials and composites formicroelectronics, Proceedings of 28th Symposium onDevices and Materials, SD 92, Portoroz, Slovenia,1992, p. 443

40. Kuzcl R, Kubat J and Votruba Z: Polymeric compos-ites for thick film resistor preparation, Proceedings of28th Symposium on Devices and Materials, SD 92,Portoroz, Slovenia, 1992, p. 349

41. Gatenholm P and Mathiasson A: Environmentallydcgradable composites, Polymeric Materials Scienceand Engineering, 67 (1992) 361. Proceedings of theAmerican Chemical Society, Division of PolymericMaterials: Science and Engineering

94 THE CENTRE FOR


Polymer Technologyand Surface Protection/Corrosion

Research summaryThe research activities of the department of PolymerTechnology and Surface Protection/Corrosion aremainly focused on increasing the understanding ofhow materials are degrading due to the application inwhich the material is supposed to be used. Heat, U V-radiation, humidity, corrosive gases, mechanicalstress etc are examples of factors which can seriouslyreduce the service life of a certain material. Investi-gations of the degradation mechanisms of differentmaterials exposed to various climates constitutes abasis for the development of methods for predictingservice life of materials, products and systems.

This research concept also demands activitiesregarding mixing and processing of materials sincethis step often is of crucial importance regarding thefinal properties of tiie manufactured product

Physical-chemical analysis methods, i.e. spectro-scopy, thermoanalysis, chromatography, SEM etc,are used for investigations on the molecular levelwhile mechanical testing equipment are used todeduce the macroscopic properties.

The research activities within the department aredivided into eight major programs:A: Durability and long-term performance of

materials - degradation mechanisms andaccelerated ageing.

B: The effect of air pollutants and other aggres-sive chemical environments - methods fortesting and evaluation.

C: Recycling/destruction of polymeric materials.D: Analysis and characterization of polymeric

materials.E: Processing of polymeric materials.F: Quality- and reliability technique.G: Mechanical properties of advanced ceramic.H: Physical keeping of documents.

AddressSwedish National Testing and Research InstituteP.O. Box 857S-501 15 Boras, SwedenPhone+46 33 165000Telex 36252 testing SFax+46 33 13 55 02

Research StaffAntal BoldizarBo Carlsson

Lennan CarlssonLars CedheimElse-Hanna ElgåsenPeter ErikssonThomas GevertAme HolmströmIgnacy Jakubowicz

Ulrika JohanssonAnn-Sofie LindgrenKenneth MöllerMonica MarkingerElvan NilssonMarie LouiseSamuelssonLeo SpilgKarin Wemstähl

Dr. Eng. Sci.Docent, Head of Surface Pro-tection/Corrosion DivisionDocentPh.D.M.Sc.Ph.D.Ph.D., Head of DepartmentDocentPh.D., Head of PolymerTechnology DivisionM.Sc.M.Sc.Dr.Eng.Sci.M.Sc.B.Sc.

Ph.D.M.Sc.M.Sc.

Major Instrumentation• Spectroscopy: FTIR (IR-microscope, ATR,

DRIFT etc), UV-VIS-NIR (integratingsphere), NMR, MS, atomic absorptionspectrometer, ICP, EDX.

• Thermal Analysis: DSC-, TMA-, and TGA-equipment, Leco TG.


SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE.Polymer Technology and Surface Protection/Corrosion

Chromatography: TLC (with densitometer),GOGCMS,HPLC,GPC.

Microscopy: SEM equipped with EDX,stereomicroscope, phase contrast microscope.

Processing and Reology: Injection mouldingmachine Klockner Fcnomatic Oocking force 80tons), Brabender extruder, laboratory calendar,form press, Struers thermopress, Monsantovulcanization simulator, melting index testers.

Mechanical Testing: Five tensile testing ma-chines for static and dynamic testing with acapacity up to 100 kN max. load, and withpossibility to choose testing climate within thetemperature range of -70-+200°C. Impacttesters, falling dart impact tester, tear tester, DeMattia fatigue tester, abrasion tester, doublefolding tester, Lupke-pendulum, equipment fordetermination of brittle temperature, flex point,elastic rejection, Vicat and HDT, compression,relaxation etc.

Equipment for durability tests: Approx. 100heating chambers, of which some are explo-sion proof, air manoeuvred etc. More than 20climate chambers are equipped with program-mable control equipment, 3 ozone cabinetswith externally controlled UV-analyzer.Weatherometers: 5 Xenotests, Suntest, Atlas(SR-35, UV-CON UC-1R, DMC, XW-WRC)and Weiss global UV. Furthermore, there aresalt-fog boxes, chambers equipped with gas-meter, muffle furnaces, cell-type ovens, auto-claves etc.

Financial SupportMinistry of IndustryNUTEKBFR (Swedish Council for Building Research)AFR (Swedish Waste Research Council)NORDTESTSwedish Rescue Services BoardSwedish National Archives

Major Fields of ResearchA: Durability and long-term performance of

materials - degradation mechanisms andaccelerated ageingParticipants: B. Carlsson, K. Wemståhl, K.Möller, E-H Elgäsen, I. Jakubowicz, Th.Gevert, AS. LindgrenCollaborators: Dept.of Polymer Technology,Chalmers University of Technology,Fraunhofer Institut, Freiburg, Switzerland,ITR, Rapperswil, Switzerland, TNO, Nether-lands, DTH, Lyngby, Denmark, VolvoPersonvagnar AB, SAAB-Scania AB, Paint-industry in Sweden, IVF, Göteborg, FMV,Stockholm, Hydro Plast AB, Stenungsund,BASF, Germany, Atlas AG, Germany.

B: The effect of air pollutants and other aggres-sive chemical environments - methods fortesting and evaluationParticipants: P. Eriksson, K. Möller, L.Cedheim, U. Johansson, I. Jakubowicz, Th.Gevert.Collaborators: ICT, Karlsruhe, Germany,Dept.of Inorganic Chem., Chalmers Universityof Technology.

C: Recycling / destruction of polymeric materialsParticipants: A. Boldizar, Th. Gevert, M.Markinger, I. Jakubowicz.Collaborators: Dept.of Polymer Technology,Dept.of Polymeric Materials, Chemical Envi-ronmental Science, Chalmers University ofTechnology, PGI, Mölndal, Ecole Polytech-nique Federate de Lausanne, Switzerland,Eidgenössische Materialpriifungs- undVersuchsanstalt, Dubendorf, Switzerland.

D: Analysis and characterization of PolymericmaterialsParticipants: Th. Gevert, K. Möller, I.Jakubowicz, L. Cedheim.Collaborators: Dept.of Polymer Technology,Chalmers University of Technology.

E: Processing of polymeric materialsParticipants: A. Boldizar, M. Markinger.Collaborators: Dept.of Polymeric Materials,Chalmers University of Technology.

96 THE CENTRE FOR

SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE,Polymer Technology and Surface Protection/Corrosion

F: Quality and reliability techniqueParticipants: L Spilg, L Jakubowicz, Th. GevertCollaborators: Industry

G: Mechanical properties of advanced ceramicsParticipants: L. CarlssonCollaborators: Swedish Ceramic Institute,Volvo Flygmotor AB, ABB Cerama AB,United Turbine AB, Institute of Technology,Linköping University, NIST, USA, Japan FineCeramic Center.

H: Physical keeping of documentsParticipants: M L Samuelsson, E. NilssonCollaborators: Swedish National Archives

Research Projects

A Durability and long-term performanceof materials-degradation mecha-nisms and accelerated ageing

The demands for high reliability and a minimizedtime duration from idea to the manufacturing of anew product are markedly increasing. It is thereforea big need for development of quanutive acceleratedageing tests. The results from these tests can consti-tute a basis for the determination of the lifetime ofdifferent materials before they are used in differentapplications.

Investigations have to be performed in order tofind methods for ageing as well as methods for thecharacterization of different climatic parameters.Knowledge of the mechanisms which are responsi-ble for the degradation processes induced by theenvironment must be gained. Methods for extra-polation of the results from accelerated tests in ordertc fit results from "in-use"-conditions must be im-proved.

The project aim is to develop test methods forevaluation of long-term properties of materials basedon knowledge of the degradation mechanisms. Thedifferent subprojects concerns several different ma-terials but the technique for artificial ageing, analysisand characterization of the materials are almostsimilar. Several projects runs in cooperation withthe industry and other research institutes.

The following sub-projects ate includedin the project:- Exterior automotive paints- Paints for wood preservation- Selective absorber materials for solar collectors- Rust protective paints- Plastic coven for solar collector- Durability of impact modified PVC- Physical-chemical properties of polymeric

films- Long-term durability of polymeric building

materials- Life-time predictions for rubber

Examples of publications:

- An FTIR, impact strength and thermal analysisinvestigation of a PVC window frame natu-rally aged for 20 years. Jakubowicz, I. andMöller K., Polymer Degr. and Stab. 36 (1992)111-120.

- Accelerated life testing of solar energy materi-als. Carlsson, B., Möller, K., Frei U., (ITR,Schweiz), Köhl, M., (Fraunhofer Inst. for SolarEnergy Systems, Tyskland). IEA-report, TaskX.

B The influence of air pollutants andother aggressive chemical environ-ments on degradation of materia:» -testing methods

Air pollutants such as sulphur dioxide have beenrecognized since a long time as powerful accelera-tors of degradation/corrosion of the common basicmetals, especially steel. As a consequence, dumpingof sulphur has been strongly reduced during the lastyears and has caused a decreased rate of corrosionmainly in densely built areas and industrial areas.

Sulphur dioxide in combination with nitrogenoxides has during the past time been attentioned as abig environmental problem and is considered to bethe reason for the accelerated degradation of histori-cal building monuments. Big international researchprograms are carried out today in order to make asurvey of the proportions of the problem and suggestcounteractions.

Concerning materials, such as plastics, paints andvarnishes, there is very little known about how airpollutants and other chemical aggressive environ-ments influence their degradation or protective abil-ity. Some negative effects on the durability of this



type of materials have, however, been reported. Forelectronic components consisting of both polymericmaterials and metals, the need of the development oftesting methods has been judged as great for theevaluation of the significance of air pollutions ontheir function.

Present R&D programs' goal is to contribute tomap the importance of various environments on thedurability of various materials such as plastics andvarious paints and varnishes. The goal is also todevelop relevant environmental test methods and atechnique for studying changes in materials causedby the influence of various types of mechanicalstresses.

Projects included:- The influence of air pollutions on polymeric

materials such as plastics, paints and varnishes.- Methods for testing of electronic components

under the influence of air pollutions.- SCC testing in H2S saturated solutions-deve-

lopment of methods.- Investigation of durability in alkaline environ-

ment - part 2.- Water vapour permeability as a function of

water content.- Durability of plastic packing.- Glass fibre reinforced plastics for transpor-

tation of dangerous goods.

Examples of publications:

- Plastics - accelerated ageing in alkaline envi-ronment. Jakubowicz, I., Andersson, K, andHägg, A., SP-report 1992:31.

- Effects of sulphur dioxide on the degradationof selective nickel pigmented aluminium oxidesolar absorber coatings. Möller, K., Carlsson,B., Eriksson, P. Proceeding at the 12thScandinavian corrosion congress andEurocorrosion '92.

C Recycling/destruction of polymericmaterials

Polymeric materials have become an integrated partof today's society, and they are used as cost effectiveand functional materials in many applications. Poly-mers have also come into the focus in the environ-mental debate, and as a result recycling has becomean important issue, both for the public opinion and inthe environmental policy.

This project focuses on the recycling of poly-meric materials for large scale use in applicationswith some demands. This implies that it is importantthat their quality can be guaranteed. The propertiesof mixed polymers depend to a large extent on themorphology of the multiphase system formed, whichwill be influenced by both composition and process-ing conditions. Another problem in some potentialapplications,e.g. in the building industry, is the long-term stability. Any processing imposes a stress onthe material, and it is well known that repeatedprocessing may lead to not wanted degradation anddeteriorated properties. It is also known that long-term use induces degradation by thermo- or photo-oxidation. To protect the polymers from negativeconsequences stabilizers are normally added. In thecase of recycled materials the situation becomeseven more complicated. Thermal history and theoriginal stabilization may vary, it is also probablethat repeated cycles of processing and ageing willhave a negative synergistic effect on the degree ofdegradation. There are, however, very little knowl-edge on these combined effects. The project isdirected towards this issue. (Fig.l)

Elongation at break - number of cycles

* Cyclei 6

Figure 1 - Elongation at break for a nominally unstabi-lized LDPE vs number of cycles of extrusion, ageing,and combined extrusion and ageing. The standarddeviations were ±8 % of the given values or less. Theextrusions were performed with a conventional labora-tory extruder, according to recommended parameters.Each cycle of accelerated thermooxidative ageing waschosen to correspond to one year or more at 25°C.

98 THE CENTRE FOR


Example of puMcation:- Repeated processing and ageing of LDPE.

Boldizar, A., Gevert, Th., Jakubowicz, I.,Bogren, M .*, Linde, M.*, Hjertberg, Th.**.Proceeding to be presented at Re '93 (Interna-tional recycling trade fair, with congress),Geneva 1993.

* Dept. of Polymeric Materials, ChalmersUniversity of Technology

** Dept. of Polymeric Technology., ChalmersUniversity of Technology

D Analysis and characterization ofpolymeric materials

This project is very tightly connected to the otherprojects. The aim of the activities within the projectis to develop and improve the sensitivity of differentspectroscopic analysis techniques.

Sensitive techniques are of crucial importancewhen it comes to investigation of minor changes inthe structure of materials. Very often severe deterio-ration of the macroscopic properties are caused bysmall changes in the polymer due to chemical and/orphysical degradation. The project is concentrated onqualitative and quantitative determination of additi-ves in polymeric materials, such as stabilizers, lubri-cants etc.

The following sub^rojects form the prefect:- Diffusion - desorption of antioxidants in

LDPE(Fig.2)- Analysis of lubricants in PVC- Analysis of antioxidant activity in polymers

Example of publication:- Diffusion of phenolic antioxidants in LDPE

Möller, K., Gevert, Th., to be published in J. ofAppl. Pol. Sci.

-t -is -i -ts 0 as i is tStsUece. i. fnm tie m4*e.,'lie six* {mm/

Figure 2 - By using a film stacking technique, wherepolymeric films doped with a diffusant are placed inthe middle of a stack of pure films, the diffusioncoefficient of the diffusant can be determined. Thefigure exemplifies the concentration profiles of anantioxidant in a film stack of polyethylene (LDPE) afterheat treatment at 50°C for 0,36 and 72 hours respec-tively. The antioxidant in this case was the dodecylesterof 2,&d'itertbutyl phenolpropionate (hindered phenol).Three doped films were used in order to obtain anappropriate total amount of antioxidant without exceed-ing the solubility of the antioxidant.

The solid curves represent theoretical valuesaccording to Rck's laws of diffusion under the bound-ary conditions given. They were obtained by using aleast square curve fitting procedure for best fit be-tween the experimental points in the figure and thetheoretical expression. The circles, squares andtriangles represent experimental values, obtained byFTIR spectroscopy, for the experimental conditionsgiven above. As can be seen, there is a very good fitbetween the experimental data and the theoreticalcurves. Moreover, the calculated diffusion coefficientsalso agree very well for the two different duration oftime. The difference in the value of the diffustoncoefficients is less than 4%.

The results above indicate that the diffusirprocess is very well described by Fick's laws of diffu-sion with constant diffusion coefficients.



E Processing and rtteologyof polymeric materials

Almost all currently applied processing of poly-meric materials are based on transport and formingof a melt. For understanding and prediction of thecourst and outcome of processes, the importance ofrheology for polymer melts is generally accepted.

One of the problems is that there is no singlecomprehensive model describing the complexrheological behaviour occurring in real processes.All existing rheological models may be regarded asspecial cases of a particular rheological phenomena,such as shear-flow or elongational flow.

Our intention is first of all to achieve up-to-dateinformation about the developments on the field oftheoretical and experimental rheology. We will fur-thermore also contribute to the development ofunderstanding of rheology and its appropriate appli-cations.

Ongoing prefects:- Constitutive equations describing rheological

properties for polymeric melts.- Flow Rate Ratio (FRR), a rheological testing

method for thermoplastics.

F Quality and reliability techniqueThe demand forquality systems in industry have ledto an increased activity when it comes to formulatingquality levels, documentation regarding processesand other activities, calibration etc. Round-robintests gain information regarding accuracy of differ-ent test methods and could be a very useful tool toharmonize the different steps in the testing perform-ance.

This project focus on round-robin tests and has asa goal to support Swedish industry in their qualityassurance activities.

Two projects are running for the moment:- Abrasion tests of cables- Round-robin-test on thermo-analythical inves-

tigations of polymers

Examples of publications:- Jämförande provning - gummimaterial, del 1-

12. Magna, A.C., Nilsson, K., Spetz, G., et al.SP-reports 1985-1988.

G Mechanical propertiesof advanced ceramics

In many high-temperature structure applications suchas in gas-turbines and reciprocating engines, partswill be subjected to cyclic loadings. Only recently ithas been accepted that a brittle ceramic such assilicon nitride can be sucseptible to cyclic fatigue.This area has been studied at SP during the last threeyears with the principal interest in fractography offatigued samples.

Participation takes place in an E A round-robinbetween USA, Japan, Germany and Sweden regard-ing mechanical testing of silicon nitride.

Participation also takes place in a VAMAS round-robin regarding fractography of ceramics. The re-sults will probably form the base for a new standardinCEN.

Examples wf puMcations:- Cyclic Fatigue of HIP Silicon Nitride at Room

Temperature. Carlsson, L. The AmericanCeramic Society 92nd Annual Meeting, Dal-las, Texas. 1990.

- Cyclic Fatigue at Room Temperature of Y-TZP and HPSN. Carlsson, L. Proceedings ofthe 1 lth Risö International Symposium onMetallurgy and Materials Science, Risö,(1990), 225.

H Physical keeping of documentsProperties of materials and methods used for infor-mation storage are investigated. Both conventionalmaterials, e.g. paper and recording materials such aspens and copying machines, as well as materialsused in modern techniques such as vidoe tapes andoptical disks, are studied.

Our main interests are connected with the perma-nence of the information, i.e. the ability of thedocument to resist changes over long periods of timeand/or the possibility tocopy or convert the informa-tion to other data carriers.

Projects:- Permanence and durability of recording on

paper- Accelerated ageing of paper

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Examples of publications:- Natural Ageing of Paper. Swedish Papers

1908-1988. Samuelsson, Marie Louise, Sorrier,K., R/. T-projektet för papperskonserveringRapport nr 4. Stockholm 1990.

- Investigations of Video Tape and Audio Tape.Mechanical and Coating Properties. Nilsson,E. SP report 1991:56. Boras 1991.


The Swedish Institute of Fibre andPolymer Technology, IFP-TEFOFormerly Swedish Institute for Textile Research, TEFO

IntroductionThe sphere of activities of TEFO is regulated by anagreement between the Swedish Government,repre-sented by NUTEK, the Swedish National Board forIndustrial Technical Development and the TradeAssociation for Textile Research.

TEFO's objective is to undertake R&D pro-gramme of work dealing with the chemistry, physicsand mechanics of fibres and fibrous materials as wellas the technology related to their production and use.

Areas of competenceChemistry, physics and mechanics of fibres andfibrous materials and technologies related to theirproduction and use.

Special equipmentFTIR, Contact Angle tester, Density gradient Col-umn, Particle Counter, Viscosimeter», Yarn Shrink-age Tester, Static and Dynamic tensile CompressionTesters, Photo Stereo Microscope, SEM, Tester forBond Strength, KawabataTesters (for measurementof tensile, shear, bending, compression and shearproperties of fabric films, paper and other sheetmaterials.)

AddressTEFOBox 5402, Origovägen 6S-402 29 GöteborgPhone:(031)824000Fax:(031)831319

Branch office:TEFO Boras, Box 55061, S-500 05 BoråsPhone:(033)136430

StaffManaging Director:Nils-Bertil Furvik, Tekn.lic.

Director of Research:Roshan Shishoo, Tekn.dr., Prof.

Heads of Department:Roshan Shishoo (Fibre Technology)Harald Åsnes (Fibre Chemistry)Bemt Johansson (Textile Testing)Håkan Damberg (Information/Documentation)

Scientific staff: 21Number of employed PhD's and Licentiates: 11Technical staff: 15Number of researchers from Chalmers University ofTechnology that spend part of their working week atTEFO in the Science Park: 2Total employees: 50

Annual turnover (1992):ca. 20 MSEK

Research projectsStructure and physical/mechanical propertiesof fibres and fibrous materialsStudies of the basic mechanisms related to the influ-ence of physical and chemical treatments on fibresand fibrous materials and interactions with theirstructures.

Studies of heat setting and desettlng propertiesof synthetic fibres and yamsThe shrinkage force of synthetic yarns as a functionof temperature and simultaneous extension has beendetermined for 30 different types. Variations inshrinkage forces have been measured on continu-ously fed yarn and frequency analysis have beencarried out for some yam types.

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THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-TEFO

By meansofanalysisof shrinkage force measure-ments on continuously fed yam it was possible todistinguish different yarn batches. That was not thecase with standard tensile test for yarn.

Analysis of heat transport mechanismsIn upholsteryThe newly developed method of measuring heattransport is using a shaped indentation device. Thegeometric shape is that of TEFOs mechanical testingdevice for sitting comfort. The heat flow in thesurface layer is measured in a compressed statecorresponding to actual use. Both transient andsteady-state heat transport is measured.

The method has been shown to be sensitiveenough to estimate the influence on comfort ofvarious components upholstery layers.

Water vapour transport in fibrous assembliesA modified indentation device intended for measur-ing the water vapour transport properties of fibrousassemblies has been built. A computer controlledwater vapour generator supplies known quantities ofvapour to a shaped indentation device.

Surface properties and surface modificationof fibrous materialsIn many application areas the surface properties offibrous material are of much greater importance thanthe bulk properties. The surface properties deter-mine e.g. dyeing, adhesion between reinforcing fi-bres and matrix in composites, and adhesion be-tween a coating and a fibrous substrate. The surfaceproperties also affect the soiling and soil releaseproperties of fibrous systems.

Research programsStudies of interfacial adhesion in fibrous materials.This work includes studies of interactions betweenfibre surface, characteristic of fibres and criticalparameters of adhesives and binders, with the aim toimprove the interfacial adhesion.

Studies of relationship between surface proper-ties of fibrous materials and their soiling and soilrelease properties.

Studies of bonding mechanisms between ther-moplastic fibres and fibrous substrates and plasticcoating. The bonding between PVC and polyamid

and polyester fibres has been investigated with themicrobond technique developed by the Textile Re-search Institute of America (TRI).

Liquid adsorption/sorption In fibrous systems.Studies of interactions between liquid adsorption/sorption mechanisms on one hand and structuralparameters of fibres and fibrous products on theother. This work is relevant to absorbent productsand wet processing of textiles.

Analysis of fibrous absorbent structures. Work hasbeen concentrated on small scale studies of theabsorption properties of fibrous networks. This hasbeen facilitated by the installation of an apparatus fordry forming of absorbent core samples on a labora-tory scale. The systematic variation of absorbentstructures has been guaranteed through changing thefluff and textile fibre combinations.

Additionally, an apparatus to determine dynamiccontact angles and a viscositymeter have been pro-cured. These specifically define the surface tensionand viscosity of test liquids used in the study ofliquid-fibre transport interactions.

Textile structures for fibre-reinforced compositesStudies have been made of the functional design offibrous reinforcing structures for different compos-ites as well as studies on interfacial adhesion be-tween matrix and fibres in end products.

Fibrous structures for use as reinforcement infibre composites. Textile structures which are spe-cially designed to have high modules and longlifetime are used as reinforcement in composites ofhard as well as flexible character. These compositesare used for products which satisfy high demands,e.g. extreme and corrosive environment combinedwith high temperatures and loads.These structuresare often fabricated of highly performing fibres suchas aramid, carbon or PEEK fibres.

A Ph.D. work involving elastomer composites,their fabrication and properties is under way. Thematrix flow through nonwoven fibrous mats hasbeen studied according to a newly developed method.The work has already got large international atten-tion.

MATERIALS SCIENCE. 1993


The analysis of mechanical properties of light-weight wool febrics relevant to garment making

The tailorability of lightweight wool fabrics and theinteraction between the ease of tailorability and theperformance characteristics of these fabrics has beenundertaken on a qualitative/quantitative basis. Toachieve trouble-free tailoring of garments madefrom the above material, the role of the mechanical/physical properties in the making-up process needsto be fully understood.

Objectives:(a) To investigate the tailorability properties of light-weight wool fabrics using production-line studiesaccording to TEFO's time and motion analysismethod.

(b) To characterise the relevant mechanical andphysical properties of wool fabrics which are impor-tant for ease of tailoring of lightweight wool fabrics.

The emphasis of this work is placed on the practicalanalysis of the tailorability of difficult lightweightwool fabrics with subsequent solutions for the mak-ing up of such fabrics. In addition to tailorabilityanalysis of overall garment production, analysis ofpart-processes such as sewing, feeding and handlingwas done usingTEFO'sCMA-analysis mcthod.Theresults were also analysed in terms of the relevantmechanical and physical properties of the test fab-rics. The properties have been evaluated using bothKES and FAST sets of instruments.

Formation, transport and eliminating of dust fromprocessing fibres, preforms and composites

Methodology and an apparatus to simulate the me-chanical stress build up in the handling of continuousfibres have been developed from first principles ofsolid mechanics and geometrical principles of textilemachinery. This apparatus is used in conventionalmechanical testing machines. It is encapsulated,works with a flow of pure nitrogen and is integratedwith equipment direct counting instruments andfilters to sample the emitted dust for analysis ofmorphology by scanning electron microscopy, SEM.

As expected from the adhesional theory of fric-tion, the stress build up during textile fibre handlingwas found to be of stick-slip type, indicating fric-

tional processes of adhesion followed by plasticdeformation or local fracture, damage. The dust isthus formed by the peak loading.

PublicationsOH AnderssonComments on "Effects of Strain Rate and Gauge Length onthe Failure of Ultra-High Strength Polyethylene Fibers".TRJ, vol 59, no 9, sept 1989

Lost yam preforming and split film based weft insert warpco-knitting, new routes for composite materials preforming.Verbundwerkstoffe und Wekkstoffverbunde, Chemniz 17-19 juni 1992

Thermal residual stresses in short fibre alumina reinforcedal-alloy matrix. ICCM 8,15-19 juli 1991, Honolulu

Vibration excitaUxi low-pressure casting, a new route toproduce metal matrix composites. ICCM 8,15-19 juli1991, Honolulu

H. DambergCurrent Situation in the Swedish Textile and ClothingIndustry. Textile Horizon, vol 9, no 1,49-50 (1989)

T. Dartman, C-H. AnderssonAdhesion Mechanisms in Joints of PVC-coated Fabrics ofPolyester and Nylon. The International Journal for theJoining of Materials, Vol 2, No 3, Sept. 1990

S. Posner, A-C EricssonControl of dye-baths in dyeing processes by neans of fiberoptical sensors. TEXTRANET-Symposium, 31 mars-1april 1992, FoTiO, Portugal

R. ShlshooFabric properties and making-up processes. Textile Asia,February 1989.

Gcgcnscitige Beeinflussung von Gcwcbceigenschaften undKonfektionsprozessen. Bcklcidung & Wäsche 7/1989

Interactions between Fabric Properties and GarmentMaking-up Processes. Lenzinger Berichte 67/1989.

Absorbency Mechanisms in Fluff Assemblies ContainingSuperabsorbcnt Polymers. ACS 63rd Colloid and SurfaceScience Symposium. Seattle, Washington, June 1989.

Analyses of Mechanical and Dimensional Properties ofWool Fabrics Relevant to Garment Making, fhe 8thInternational Wool Textile Research Conference.Christchurch, New Zealand, February 1990.

104 THE CENTRE FOR


Research in Automation of Clothing Manufacture inRelation to Fabric Properties. Symposium on Technical andIndustrial Textiles. New South Wales, Australia, February1990.

Product/Process Development Using Fabric ObjectiveMeasurement Technology. Awtomcc Seminar, Australia,February 1990.

Interaction Between fabric properties and garment making.Apparel International No 3 March 1990.

Investigation of Degree of Set and Deset for PET andNylon 6.6 Yams. Lectures 15th IFATCC Congress, LucernSwitzerland, June 1990.

Relation between fabric mechanical properu>s and garmentdesign and tailorability. International Clothing Conference,Bradford, July 1990.

Relation between fabric mechanical properties and garmentdesign and tailorability. Int J. of Gothing Science andTechnology vol. 2 (1990)3/4 pp.4047.

Relation between fabric mechanical properties and garmentdesign and tailorability. Int. FAMOS(EUREKA) Workshopon Flexible Automation in Textile and Apparel Industries.Oporto, Portugal, nov. 1990.

Fabric Tailorability. Textile Asia, dec.(1990) pp.64-69.

Use of the Kawabata Evaluation System of Fabrics (KES-F) in the clothing industry.30th International Man-Made Fibres Congress Dombirn/Austria, 12-14 juni 1991.

Enduse opportunities for viscose rayon fibres.Conference Progress in Cellulosic Man-Made Fibres, arr.Berol Nobel, 10-12 september1991, Arken Göteborg

Fabrication Methods for Latex-Based Elastomer Compos-ites Reinforced with Long Discontinuous Fibres. Journal ofApplied Polymer Science, Vol 44,263-277 (1992).

Relation between fabric mechanical properties and garmentdesign and tailorability. 'Textile Objective measurementand automation in garment manufacture",Ed G. Stylios.Publisher Ellis Horwood.

Consumer demands and technical challenges fornonwoven-based protective clothing. EDANA's 1992International Nonwoven Symposium 12 and 13 MayMunich.

New process for fabricating nonwoven fibrous reinforcedelastomere composites. 4th International Techtexiil Sympo-sium June 1992.

Geometrical-Mechanical Properties of Polyester KnittedFabrics. Abstract of the 21st Textile Research Symposium(Mt Fuji) p. 173 (1992).

Use of Objective Measurements in Garment Production andDesign. Abstract of the 21st Textile Research Symposium(Mt Fuji) p. 176(1992).

Analysis of Mechanical Properties of Lightweight WoolFabrics Relevant to Garment Making. Proceedings of the2nd International Clothing Conference, Univ. of Bradford,7-9 July 1992.

A New Process for Fabricating Nonwoven Fibrous-reinforced Elastoner Composites. J. Appl. Polymer Sci.,Accepted for publication.

Material development for high functional clothing in the90's. Proceeding of Int. Symposium on Textiles andComposites '92, Tampere, 1992.

Analysis of Structure - Absorbcncy Relationships inDisposable Hygienic Products. International Conference onNonwovens, Decemlxv 9-11,1992, New Delhi, India.

Analysis of Physical and Mechanical Properties ofNonwovens for Use in Protective Garments. InternationalConference on Nonwovens, December 9-11,1992, NewDelhi, India.

R. Shlshoo, M. EpsteinFabrication methods for latex-based clasiorricd compositesreinforced with long disconu'nous Fibers. Journal of AppliedPolymer Science, vol 44, no 2, jan. 1992.

B. StenemurFascrvlicsbindung mit Polymerdespcrsionen.Chcmiefascm/Textilindustrie, vol 39/91,294-298 (1989)

Vliessioff - Forschung in Schweden. Chcmiefascm/Textilindustrie, vol 39/91,299 (1989)

Method and device for monitoring Tiber orientation distri-bution and web uniformity on running sebs of paper andnpnwovcns based on light diffraction phenomenon. IndaJournal of Nonwuvcns Research, vol 4, no 2., 1992.

G. Waldert, H. ÅsnesTumble Drying Acrylic, Modacrylic or PolypropyleneFabrics, American Dyest;iff Reporter, vol 79, no 2, Febr.1990.

J. Wang, H. ÅsnesOne-bath dyeing of wool/polycstcr blends with acid anddisperse dyes. Part 1 and 2, Journal of the Society of Dyersand ColourisLs, 107 (1991) 274-279 and 314-319.


The Swedish Institute of Fibre andPolymer Technology, IFP-PGIFormerly Swedish Plastics and Rubber Institute, PGI

TheSwedishPlasticsandRubber Institute, PGI.isanindependent research organisation sponsored by theindustry and the Swedish government via NUTEK(Swedish National Board for Industrial and Tech-nical Development). More than 80 Scandinavianindustries are members of the institute.

The Institute was founded in 1977 and has today17 employees. The average educational level of theemployees is high, with 5 Ph.D., 5 Masters and 4engineers. Besides most of the staff has a longindustrial experience from different kinds of poly-mer and manufacturing industries.

Presently PGI is active in three main areas of re-search:- Computer aided engineering for polymer

processing and analysis- Processing and production methods- Materials and recyclingPGI carries out industrial research and developmentwork for the participating industries. The open re-search projects are proposed and directed by repre-sentatives from the industry. The results from theseprojects are presented in PGI-reports. Multiclientresearch projects for a smaller group of industries arealso undertaken.

PGI also performs consultant work for all typesofindustries. The results of that work are strictly con-fidential and no financial support is given by NUTEK.

PGI annually arranges courses and conferencesin connection with on-going projects and other ac-tivities. The institute also participates in education atdifferent levels within our member companies and inthe education at Swedish Universities.

AddressPGIKrokslätts Fabriker 30S-431 37 Mölndal, SwedenPhone+46318635 80

StaffGeneral ManagerCAEProcessingMaterial andRecyclingConsultant work

Rolf Ericsson, Ph.D.Jan-Erik Rosenberg, Ph.D.Per Albihn, Ph.D.

Ingrid Gustafsson, Ph.D.Staffan Ek, M.Sc.

Major InstrumentationSimulation and Calculation• 2. HP 9000-730 PVRX work stations.• 1. HP 9000-360 SRX work station.• SDRC IDEAS for Plastics: Solid geometry

based program for CAD, linear FEM withcomplete rubber and plastics design andproduction analysis including mould designand warping of finished parts.

• Abaqus, linear and nonlinear FEM program.• Moldflow, Moldfill, moldfilling simulation

programs fcr plastics.

Production machinery• Demag D 152-452 Injection moulding machine

for rubber and plastics. Locking force 1500 kN.• Brabender DSK 42/7 twin screw compounding

extruder.• Brabender internal mixer for rubber and plas-

tics, capacity 400 g.• Roller mill for rubber.• Instrumented injection moulding tools for

rubber and plastic.

Mechanical test equipment• 6 MTS servohydraulic testing rigs for dynamic

and static tests. Max load 25-50 kN. Frequency.01-150 Hz. Climate chamber.

• Monsanto TensometerlO tensile tester forrubber. Max loadlOkN. Climate chamber.

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THE SWEDISH INSTITUTE OF FIBRE AND POLY MER TECHNOLOGY, IFP-PGI

• Instron tensile tester, max load 10 kN.• Computerized pendulum impact tester with

time/force registration• PGI computerized falling weight impact tester

with time/force registration.• Zwick hardness tester for plastics.» Wallace hardness and microhardness tester for

rubber.• PGI creep rig with temperature chamber.

Rheologlcal characterisation• Bohlin CS-melt dynamic rotation viscosimeter

for creep and relaxation• Bohlin Visko 88 rotation viscosimeter for

liquids.• Shimadzu CFT-500 Capillary Viscosimeter for

melts and powders.• CEAST 6540/010 Melt Index tester.• Davenport 423 Capillary Viscosimeter.• Monsanto Rheometer 100 for rubber vulcani-

sation.

Thermal and material analysis• PerkinElmerDSC7andTAC7.• Polymer Laboratories DMTA Mk II.• JEOL JSM T100 SEM and sputter JST 1100

for gold coating.• AGEMA Thermovision 870 heat camera and

video recorder.

Other facilities• Ovens for accelerated heat ageing.• Ozone testing chamber.• Climate chambers.• Weather simulators.• Microwave vulcanization plant.• Computer programs for evaluation of ageing,

factory layout, databases for material selection.All instrumentations are in principal availablefor external users. Contact person, Staffan Ek,tfn 031-86 35 80.

Major Reids of ResearchA: CAE - Computer Aided Engineering for

Polymer Processing and AnalysisDr Jan-Erik Rosenberg

B: Processing of Rubber and ThermoplasticsDr Per Albihn

C: Materials and RecyclingDr Ingrid Gustafsson

Research Projects

A: CAE-Computer Aided Engineering-for Polymer Processing and Analysis

A l : Optimization of design, mould and processFor the design of polymer parts it is important that thematerial's unique properties are used as effectivelyas possible. Insufficient knowledge of the rheologicaland mechanical properties of polymer parts oftenresults in unsatisfactory designs and moulds. Inorder to achieve good results, the most effectivecombination of geometry, material, mould designand manufacturing parameters is needed. PGI iscurrently working at gathering knowledge about thedevelopment process of a part, and at optimizing themanufacturing process by using CAE-technique.The demands on the process related to a finishingtreatment, laquering, is also considered.

A2: Quality control in the productionof moulded parts

For manufacturers of injection moulded parts, qual-ity has to an ever increasing extent become animportant tool in competion. The future will bringabout higher demands on the manufacturers and callfor active quality control of every single producedpart. This involves automatic control of the part at theproduction stage, and if quality demands are not met,immediate rejection. This requires a large amount ofmeasurements, both of the process and of the pro-duced parts, in order to find the mathematical con-nections used as input in a quality control system.The objective of the project is toestablish the advan-tages with an active quality control system. A basisfor minimizing the time and cost consuming work togather input to the quality control system will also beformed.


THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-PGI

A3: Mechanical straight - wekflinesHigher demands are now also made on the endproduct. Product properties are often not the same asin tests specimen, for example weld lines are weak-ening factors in many products and the properties arealso influenced by flow length. In this project, prop-erties of injection moulded parts with weld lines arestudied, and relations between process parametersand weld line properties are established. The aim isto give instructions as how to dimension parts withweld lines.

A4: Knowledge based systemsIn many companies today there are problems withtaking care of all the information, know-how, guiii-ered during different development projects. Thepurpose with this project is to develop a knowledgebased system. This system will include know-how inorder to facilitate future developments and to in-crease product quality. The system will also makesure that continuity in the development process ismaintained and that the influence of personnel andreorganizations is minimized.

A5: Compounding, designing and processingrubber parts

One of the purposes with this project is to develop aknowledge based system where the methods ofexperienced compounders will be implemented. Theadvantages with such a system is, for example,simpler recipes, standardization possibilities andtime reductions. For the company using the systemit is also a good way to take advantage of differentpersons'knowledge.

The calculations of strains and deformations inthe designs of rubber parts can be very difficult sincethe rubber material model is complicated and de-formations, extensions and interferences betweenrubber and surrounding walls are substantial. As aresult, the calculations are highly non-linear andtherefore considerably more complex to handle thanthe linear calculations used for dimensioning metalparts. The purpose is to compare calculated andmeasured static stresses and to evaluate the results.

PGI has also begun a cooperation with a softwaresupplier to increase the possibilities for calculationson rubber materials. The aim is to develop a softwarethat makes it possible to analyze the mould fillingprocess of rubber parts. The software is expected tobe commercially available during spring 1993.

B: Processing of Rubber andThermoplastics

B l : Rheology of RubberThe rheology of rubber polymers and finished rub-ber compounds is studied. The influence on process-ing behaviour of the polymer molecular structureand different types of carbon black is investigated.EPDM and SBR rubbers are caracterised for varia-tion in molecular structure (long chain branching)and molecuiiu weigth and molecular weigth distri-bution using NMR, IR and SEC. P heological behav-iour of the polymers and compounds are measuredon capillary and rotational viscosimeters and corre-lated with industrial processing (compounding ininternal mixers and injection molding).

A study has shown that present standards andinstrumentation can not predict processing behav-iour even for well standardised material while se-lected rheological data were able to correlate withprocessing performance.

The project aims to develop a standard reheologi-cal measurement for raw materials, processing rub-ber compounds and process control.

B2: Practical rheology-evaluation of rheologicalcharacterisation of rubber material

Many different rheological methods and instrumen-tation are used by the rubber industry. The projectwill study which type of rheological data that bestdescribe the processing ability of compounded rub-ber material. Selected modem rheological instru-mentation will be evaluated and measurement re-sults will be related to actual process performance fordifferent processing operation.

B3: Multilayer Injection moulding of rubberPGI has developed a method to produce a three layerrubber product in one moulding operation. Contraryto thermoplastics, multilayer injection moulding ofrubber products is a stepwise process, one materialbeing injected at each step using moving parts in themould.

The flow behaviour of rubber in the mould isindustrial know-how and is not reported in thelitterature.

The rheological and geometrical conditions thatcontrols the multilayer formation will be investi-gated. The processing conditions (mainly tempera-ture, injection speed and pressure) that controls the

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THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-PGI

multilayer formation will be evaluated for severalrubber materials. To further promote adhesion be-tween different rubber materials coupling agentswill be used. The project aims at a complete indus-trial process and to produce finshed multilayer prod-ucts in one moulding operation.

1. E Vos, H. Meijer, G Peters, Multilayer InjectionMoulding: Intern. Polymer Processing IV (1991) I s42-50.

B4: Injection moulding techniqueThe project studies quality in injection mouldingusing the latest machinery and instrumentation.Computer control of the injection process is nor-mally done by controlling the injection unit. Ad-vances in computer technology now enabels processcontrol by sensors in the mould.

Heat transfer in moulds also contributes to pro-duct quality. Temperature distribution in finishedparts and in moulds are studied using heat cameratechnique.

B5: GasinjectInjection of compressed gas in the melt duringinjection moulding is a novel method that haveseveral advantages. Parts with a hollow interior havelower weight, and a uniform wall thickness caneliminate sink marks. The gas distributes pressurebetter and machines with lower clamping force canbe used. The process also faciliates new constructionsolutions for many parts.

PGI will evaluate the advantages and limitationsof the process together with industrial companiesthat are using the process.

1. H Eckhard. KontinuierlicherGasinnendruck beimSpritzgieBen, Kunststoffe 82 (1992) 10.

B6: Precision Injection mouldingMany advanced materials such as LCP-polymers,high performance blends and special compoundsrequire special processing conditions for optimumperformance. The products that are produced inthese materials are ofen used in complicated applica-tions with high demands on product quality. Theinfluence of processing conditions on material pro-perties are often limited, even from the raw materialproducers.

The project will study the influence of the pro-cessing conditions on properties of finshed part inselected advanced materials.

B7: Effective start-up of injection mouldsEach new injection mould has to be run in. Thesetting of the production parameters are usually doneby earlier experience. The process can take severalhours. With the use of modem statistical methodsthis can be speeded up and a higher quality of theproduct be assured.

The project is a multiclient study of how to makebest use of commercially available statistical pro-grams for opimization of mould start up and qualityassurance of injection moulding.

Joint project with IYF, Swedish Institute forProduction Research.

1. P Karlinger. E Biirkle. Von Qaulitetsmerkmalenzu Einstelldaten.Kunststoffe 82 (1992) 3 s 175-179.

B8: injection moulding of long fibersThe fiber reinforcement of injection mouldablethermoplasics are made up of relativly short fibers,normally 0,1-1 mm long. Some materials with longerfibers are commercially available but in many app-lications the fibers are damaged by the injectionmoulding process.

The project will study the interfacial mechanismsof the fiber polymer bonds during the mouldingoperation. The surface treatment of the fibers (thesiiane coupling agents) will be optimized forrheological properties during moulding as well asmechanical strength of finished parts.

Joint project with YKI, Swedish Institute forSurface Chemistry.

C: Materials and RecyclingThese projects fall into three main categories; Dura-bility test of polymeric materials, Environmentalrelated projects and Recycling.

Cl: Durability tests of polymeric materialsDegradation of polymeric materials is a very com-plex process, which makes it difficult to predict thelifetime for engineering polymers. PGI has during along period studied several methods of determining


THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, 1FP-PGI

expected lifetime of plastic and rubber materials.Thereby several different methods have been evalu-ated.

A very comprehensive study was made on rub-bers and thermo-plastic elastomers. The degradationwas studied in air, water and oil and was performedduring five years.

The durability of mineralfilled polypropylenehas been studied extensivly in the last five years.Accelerated aging in oven at 125°C was performedand the lifetime of the material was determinedas the impact properties decreased below fifty per-cent of the original values. It was found that thelifetime of the mineral-filled polypropylenes variedfrom two weeks to over one year depending onwhich mineral the material was composed of.

Studies are now performed to relate acceleratedaging in oven to other more quicker methods. Theoxygen induction time (OFT) is measured in a dif-ferential scanning calorimeter and related to theresults from accelerated aging in ovens.

The remaining amount of different antioxidantsare studied in aged materials by using supercriticalfluid extraction (SFE) on line with supercritical fluidchromatogranhy (SFC). Both qualitative andquantitative measurements are performed using aflame-ion detector.

C2: LJfecycle assessment (LCA)LCA studies are made to analyse and assess theenvironmental impact of a material, product or ser-vice throughout the entire life cycle. LCA should becomposed of four different steps; goal definition,inventory analysis, impact analysis and valuation/-improvement analysis.

LCA can have various purposes:- To calculate the environmental impact for

specific life cycles.- To compare alternative products, processes or

services.- To identify parts of the life cycle where the

greatest improvements can be made.

PGI is working with the inventory analysis forplastic and rubber materials. One of the difficultiesencountered during the inventory is to find all thenecessary data about the processes and transporta-tion in the life cycle. On a methodological levelquestions defining the system boundaries and the

functional unit are studied. Depending on the systemboundaries surrounding conditions may have to beassumed and rules for allocation may have to bedecided to be able to calculate the environmentalimpact in waste handling processes or processeswith several products.

C3: Recycling

If recycling of polymeric materials should be suc-cessful many problems must be solved within dif-ferent fields. If recycling should be used on a largescale in applications with high demands it is neces-sary that the quality of the recycled material issufficient. To garantee long-term properties for re-cycled material becomes even more difficult thanfor virgin material.

It is known that long-term use induces degra-dation by thermo-oxidation or photo-oxidation. Toprotect polymers from this, stabilizers are normallyadded. With recycled material the situation becomesvery complex. The thermal history and the originalstabilization may vary. Repeated cycles of process-ing and ageing may have a negative synergisticeffect on the degree of degradation. However thereis very little knowledge on these combined effectsand PGI is using SFE-SFC technique to study howto restabilize recylcled material to be able to improvethe long-term properties of these materials.

C4: Recycling of polymer blends

The best way to get good properties for the recycledmaterial is to separate the waste after polymericidentity. However it is not always possible todo this.Sometimes it can be economically more favorable toreuse the material as a polymeric blend.

Most polymer combinations are however incom-patible and they give a multiphase material with poormechanical properties. It is widely known that thepresence of certain blockcopolymers, compatibi-lizers, can increase the miscibility of different poly-mers. Suitably chosen it will alter the interfacialsituation leading to improved mechanical proper-ties.

PGI is studying the possibility to upgrade themechanical properties of recycled polymer blendsby using commercially available compatibilizers.

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Publications

Diploma ?.orkC Grönvall eL al., "Mould filling simulations of thermo-plastic parts", 1990

L Jansson, J Magnusson, "Mould filling simulations ofrubber parts", 1992

L Lekscll eL al., "Warpagc and shrinkage - An evaluationofl-DEAS Plastics", 1992

N Alveby, "Study of the compatibilizing effect onpolypropylcnc/polyamidc blends", 1993

Reports and articles"Mould Tilling simulations of thermoplastic parts",C Grönvall et. al., PGI-report no 104,1991.

"Warpage and shrinkage - An evaluation of I-DEASPlastics", L Leksell CL al., PGI-report no 111,1992.

"Ihc use of Swedish minerals as fillers in thermoplastics",G Mälhammar, PGI-report no 81,1988.

"Swedrh minerals as Tillers in thermoplastics", GMälhammar, PGI-report no 98,1990.

"Minerals in polymeric systems", I Gustafsson, GMälhammar, PGI-report no 109,1992.

"The effect of mineral fillers on impact and tensile proper-ties of polypropylene", L Jilkén et. al., Polymer Testing 10,(1991),329-344.

"Degradation of rubber materials and thcrmoclasiics in air,water and oil", Å Eliasson, H Tjömvik, PGI-rcport no 113,1992.

"A comparison of process-techniques for SBR 1500materials from four different suppliers", T Hjertberg et. al.,PGI-report no 96,1989.

"Simplified production control during injection mouldingof thcrmo-plastics", C Bengtsson, O Krugloff, PGI-reportno 70,1987.

"Polymer melt rheology - an introduction", B Hagström,H-E Strömvall, PGI-report no 105,1991.


BiomaterialsSurface Physics 114

MATERIALS SCIENCE. 1993

Surface Physics

Research SummaryThe group's research comprises basic research andapplied research within the field of surface scienceand chemical physics. The basic research is focusedon dynamics and kinetics of surface processes, espe-cially molecule-surface interactions. Tworeoccurring, important issues are: i) description ofindividual steps (adsorption, desorption, surface re-actions etc.) forming the reaction sequence and ii)what do the potential energy surfaces which governthe reaction dynamics look like? Surface processesinvolvingchargetransferduringmoleculardissocia-tion (accompanied by light and electron emission),replacement type reactions, photo-induced reactionsand catalytic reactions are typical playgrounds werethe above issues are explored. Kinetics of surfacecatalyzed processes as well as the description ofcatalytic ignition are also of central interest. Appli-cation oriented research is focused around kineticstudies of car exhaust catalysts and metal-oxidecatalystsfor catalytic combustion of methane. A linkhas been established between the basic research onmodel catalysts (single crystals) in ultra high vacuum(UHV) and applied work on supported catalysts,either underUH V conditions or at higher pressure (1atm). This link also comprises industry collabora-tion.

A multidisciplinary research within the field ofbiomaterials has grown rapidly within our groupcontaining both basic and applied components andindustrial collaboration. The basic research aspectsare focused on issues related to the interaction be-tween water, simple biomolecules (amino acids),and proteins with model bioimplant systems. On theapplied side, issues of controlled growth of oxidesurfaces on bioimplants and the role of surfacestructure on the adsorption of biomolecules areexamined. Microfabricated surfaces down to thenanometer level and chemically modified surfacesare central in this research.

AddressDepartment of Applied PhysicsChalmers University of TechnologyS-41296 Göteborg, Sweden

Phone+46 31 772 3370Fax+46 31 772 3134

StaffSenior membersBengt KasemoIgorZbricJukka LausmaaAnatole KrozerDinko Chakarov

Secretary

professorPhD.fil.dr.tekn.dr.Ph.D.

Anne-Christine Lindbom

Graduate studentsBjöm-Owe AronssonJulie GoldLars HellbergPer HjortPatrik JohanssonStaffan LundgrenPeter LööfBengt OlssonMats RinnemoMichael RodahlPer SalomonssonClaes ÅkerlundLars Österlund

civ.ingM.Sc.fil. kand.fil.kand.fil.kand.fil.kand. (at AB Volvo)civ.ingciv.ing (at AB Volvo)civ.ingciv.ing, M.Sc.civ.ing (at CIT)fil.kand.fil.kand.

Major Instrumentation• Molecular beam scattering apparatus for

studies of reactive molecule-surface scattering(incl. LEED, rotatable mass spectrometer, highenergy beam)

• Molecular beam scattering apparatus forstudies of surface chemiluminescence (incl.photon counting facility, sticking measure-ments on reactive species)

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Surface analysis system (facility for UPS, XPS,AES, ISS studies of surfaces with sample loadlock system)Combined UHV-high pressure apparatus forstudying catalytic and other surface reactions(includes AES, HREELS, TPD, MS, LEED,UV photon beam)Molecular beam mass spectrometerEquipment for plasma preparation of materialsFlow reactor with on line mass spectrometryCombined UHV-high pressure apparatus forstudies of metal hydrides (AES, XPS, QCM, MS)Thermal desorption spectroscopy equipementEquipement for hydration-dehydration studiesof various materials at atmospheric pressureSTM and AFM for topography and imaging ofvarious surfaces.

Financial Support• Nutek• TFR• NFR• Knut and Alice Wallenberg Foundation• Industry


A: Dynamics and Kineticsof Surface-Molecule Collisions

Participants: Lars Hellberg, Bengt Kasemo, IgorZone, Claes ÅkerlundCollaborators: profs. B. Cooper and W. Ho, CornellUniversity, USA, profs. B.I. Lundqvist and S.Andersson (CTH)

B: Reactivity of Caibon Surfacesand Photoinduced Surface Processes

Participants: D.Chakarov, Bengt Kasemo, Karl-ErikKeck, Lars österlundCollaborators: C. Janiak, Frie Universität, Berlin,prof. R. Hoffman, Cornell University, USA

C: Catalytic Reactions Relatedto Energy and Environment

Participants: Bo Hellsing, Bengt Kasemo, Karl-ErikKeck, Staffan Lundgren, Peter Lööf, PerSalornonsson

Collaborators: profs S. Andersson, B.I. Lundqvist,A. Rosen, (CTH), W. Ho (Cornell), V. P. Zhdanov(Institute of Catalysis, Novosibirsk, Russia), Emis-sion Teknik AB, Volvo AB, EKA Nobel AB., T.Griffin (ABB, Heidelberg)

D: Catalytic IgnitionParticipants: Mohammad Fashihi, Mats Rinnemo,Bengt Kasemo, Karl-Erik KeckCollaborators: V. P. Zhdanov (Institute of Catalysis,Novosibirsk, Russia)

E: Kinetics and Thermodynamicsof Metal Hydrides

Participants: Per. Hjort, B. Kasemo, A. KrozerCollaborators: prof. L. Schlapbach (Fribourg,Switzerland) V. P. Zhdanov (Inst. of Catalysis,Novosibirsk), prof. E. Karlsson's group, UppsalaUniversity

F: Biomaterial Surfaces and BlocompatibilrtyParticipants: Bjöm-Owe Aronsson, Julie Gold, PatrikJohansson, Bengt Kasemo, JukkaLausmaa, MichaelRodahlCollaborators: Prof. I. Lundstrom's group at theLaboratory of Applied Physics, Linköping Univer-sity; The Nanometer Laboratory, CTH; Departmentof Anatomy, Göteborg University; Medical Scien-ces Research Institute, USA; Nobelpharma AB,Several orthopaedic and other clinics

G: MicronicsParticipants: Bjöm-Owe Aronsson, Julie Gold,Michael Rodahl, Anatole Krozer, Peter Lööf,Mohammad FassihiCollaborators: Prof. I. Lundstrom's group at theLaboratory of Applied Physics, Linköping Univer-sity; The Nanometer Laboratory, CTH; Departmentof Anatomy, Göteborg University

Research Projects

A: Dynamics and Kineticsof Surface-Molecule Collisions

A l : Charge Transfer Reactionsand Surface Chemlluminescence

This project is concerned with the reaction of halo-gen molecules and atoms with alkali metal surfaces


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(e.g. CI2 on a potassium surface). The choice ofreactants can be regarded as a model system forcharge transfer at surfaces, where parameters are e.g.the work function, electron affinity levels, and den-sity of states at the Fermi level. As a consequence itis possible to observe phenomena like emission ofcharged particles and light. This is more rarely seenin other systems where charge transfer is also knownto be important, such as molecular dissociation ontransition metals.

The motivation to perform these experiments istwofold. On the one hand, the phenomena observedare very interesting as such and are well worth tostudy. On the other, we believe that important newknowledge will emerge which will be possible togeneralize on other surface (catalytic) reactions. Ourinitiated studies on photoinduced desorption areconceptually and theoretically closely connectedwith this project (see B below).

A new molecular beam scattering apparatus hasbeen constructed for these studies. It was initiallyused to study various aspects of the atomic lightemission from the K4p-4s transition observed in theCI2 gas + K solid reaction. At later stage a facility tomeasure the absolute sticking coefficient and anAuger Electron Spectrometer were added in order tocharacterize the surface composition. The latestmodifications have recently been used to measurethe sticking coefficient of CI2 on a clean potassiumsurface. In general the equipment is designed forstudies of the different branches in e.g. in alkali-metal/halogen gas interactions such as, surfacechemiluminescence, photon-, electron-, and ionemission, and excited particle emission.

A2: Reactive Molecular Beam ScatteringThe main scientific goal of this project is to under-stand surface reactions on the atomic level. This isbest achieved once the details of the potential energysurface (PES) topology are established. Particularregions of the PES, called activation barriers playvery important roles since their size and location inthe reaction coordinate space determine reactionrate, as well as the energy degrees of freedom of thereactant which is most effective in getting them"over" the barrier into the product region. The ex-perimental method used to probe PES consists of asupersonic beamofreactantsimpingingon the modelcatalyst surface. The analysis of the reflected, stuck,and reacted fraction yields valuable information

about kinetics and dynamics of the particular surfaceprocess under study.

A search for the Eley-Rideal reaction mechanismhas been conducted in processes involving CO im-pinging on CO, O2 or NO adsorbed on Pt(lll)surface 43. A search for CO2 produced in a directpick-up process, for different beam energies, incom-ing angles and degrees of vibrational excitation wascarried out Upper limits for these particular reactionprobabilities were found to be very low (<10-5). Anexplanation for these low values was related tosymmetry properties of the reactant HOMO andLUMO orbitals as well as to their position within thePt conduction band.

A second surface reaction studied was the re-placement of O2 on Pt(l 11) surface by incident COmolecules 48. We have studied this particular proc-ess as a function of O2 coverage, CO kinetic energyand surface temperature. Furthermore, we have alsomeasured the associated CO coverage and energyand coverage dependence of the CO sticking coeffi-cient. The main findings include a strong variation ofthe replacement cross section with incident energyand O2 coverage. These results are contrasted by theabsence of O2 removal from the surface when ex-posed to a beam of Ar atoms or O2 molecules havingthe same energy as the CO mole .ules. These resultssuggest a dynamic energy transfer between the in-coming CO molecule and the adsorbed O2 as acandidate for the replacement mechanism.

B: Reactivity of Carbon Surfaces andPhotoinctaced Surface Processes

The technological background for this project is theknown influence of additives on the reactivity ofcarbon materials towards oxidizing molecules. Purecarbon in graphitic form is remarkably resistant tooxidation. In contrast alkali metals may enhance theoxidation rate in O2 by several orders of magnitude.This phenomenon has implications for carbon gasi-fication (e.g.. fuel production), carbon combustion,soot combustion in diesel particle filters, etc.

In this project the reactivity of carbon surfaceswith additives is studied by a combination of kineticmethods, primarily Thermal Desorption Spectro-scopy, and spectroscopic methods. Specifically, westudy coadsorbates of potassium with O2, H2O,CO2, or NOX, respectively on graphite.

Examples of recent results are that dissociativesticking of O2 on graphite 59 is enhanced by > 103

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times by as little as O.OS monolayer of potassium.Several KOX surface precursor complexes preced-ing CO2 formation from O2 + graphite, have beenidentified by high resolution electron energy lossspectroscopy 5 !. These results have stimulated theo-retical work by Dr. C. Janiak and Prof. R. Hoffmanat Berlin and Cornell University, respectively. Re-cently we have also started a study of photochemicalreactions involving visible-UV light irradiation ofpotassium and potassium complexes with O2, H2O,CO2, and NOX on graphite.

C: Catalytic Reactions Relatedto Energy and Environment

This project involves active industry collaboration.The common theme is catalytic oxidation of hydro-carbons and/or H2, either for car exhaust emissionreduction or forcombustion of primarily methan t. Inthe former case noble metal catalysts are studied, inthe latter metal oxide catalysts. For car exhaustcatalysts modifications of catalyst properties due tosupport interaction has been studied37-69 (Pt and/orRh on AI2O3 and COX respectively). Recently thesintering of small Pt particles on these supports, asinfluenced by H2,02 and NO has been studied 57.

Combustion catalysis of CH4 combustion arestudied with respect e.g. to activity, oxygen capacityand reaction mechanisms. The kinetic studies arecombined with surface spectroscopic characteriza-tion of the catalysts.

D: Catalytic Ignitionand klnetik modeling

The questions addressed in this project has a basicscience component and an applied one. The centralissues include critical conditions, transients and in-stabilities in catalytic reactions like ignition, extinc-tion, oscillations and chaotic behavior. Combinedtheoretical and experimental efforts have advancedthe understanding of the ignition phenomenon in theH2+O2 reaction on Pt at 1 atm 7 •. The experimentalapproach consists of measuring pre-ignition kineticsand the ignition temperature for water production onPt as a function of H2/O2 mixing ratioat atmosphericpressure, gas flow parameters, surface temperatureetc. In this pressure range surface kinetics, heatbalance and mass transfer are responsible jointly forthe observed catalytic ignition. A computationalprogram for calculations of the time dependentcoupled equations describing kinetics of surface

reactions, heat, and mass transfer, has been devel-oped. The model iscapableof a quantitative descrip-tion for the ignition sequence in the H2/O2 system onPt over wide range of parameters. In particular thetransition from the low temperature, kinetically lim-ited reaction to the high temperature, primarily masstransport limited reaction is now well understood 52.

This project also contains a subproject aimed atcomputer modeling of kinetics of primarily catalyticreactions. The model system has from the beginningbeen the H2/O2 reaction on Pt and connects theactivities under A2 and C above. Basically, theapproach is to construct a kinetic model involvingthe known or assumed steps of the reaction, tocalculate (i) surface coverages of participating spe-cies and intermediates, and (ii) calculating the ratesof individual steps. This requires knowledge aboutsticking coefficients (including their coverage de-pendencies), rate constants and activation barriers(including also their coverage dependencies) and soon The interplay with experiments, probing thecalculated quantities is vital. In the collaborationwith Ame Rosen's group the H2/O2 reaction hasbeen explored using calorimetry to measure theabsolute PbO production rate, and laser inducedfluorescence to measure the simultaneousdesorptionrate of the intermediate OH in the reaction (forpressures 1 - 1000 mTorr and temperatures 900 -1300 K). This has resulted in a currently fairlyaccurate model, within the so called mean fieldapproximation, (for the H2/O2 reaction on Pt). Thesame model predicts correctly the OH desorptionfrom pure H2O and H2O+Oa mixtures on Pt 53, andalso accounts for the ignition of H2/O2 mixturesdiscussed above.

E: Kinetics and Thermodynamicsof Metal Hydrides

In this project we have studied the formation kineticsand electronic properties of (mainly) MgHx. Mg -hydride is a possible candidate for hydrogen storagein certain technological applications, e.g. heat pumps,catalytic combustion (as internal hydrogen source),etc., and may also serve as a model material to studythe problem of hydrogen embrittlement. The projectwas naturally divided into two stages.

In the first stage we investigated the kinetics ofuptake and the phase diagram of hydrogen by Pdcoated Mg films15. The samples were prepared by


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UHV-evaporation on a sensitive quartz crystalmicrobalance and hydrided in-situ at pressures 10-3- 1 0 Torr in a hydriding cell attached to the UHV-system The main findings are: There is a pressure-temperature regime (nigh p - low T) where thermo-dynamic equilibrium between the H2 gas and Pdcovered Mg sample cannot be reached due to inter-face hydride formation at the Pd-Mg interface. Theinterface hydride grows until it coalesces and blocksfurther hydrogen diffusion towards the (unhydrided)interior of the sample. This was inferred from theobserved kinetics, and proved by nuclear micro-analysis measurements performed by Prof.. ErikKarlsons group, Uppsala University.

A theoretical model describing the formation andgrowth of the interface hydride developed in col-laboration with Prof.. V. Zhdanov, Novosibirsk 61.The model agreed semiquantitatively with the ex-perimental results. The model is applicable not onlyto the H - Mg system, but describes the kinetics ofany 1st order phase transformation which is drivenby the (surface) source term.

There is also a p - T regime Qow p - high T) whereequilibrium can between H2 gas and MgHx can beestablished. In this regime we have measured thehydrogen absorption anddesorption isotherms, andassociated kinetics, at 105 times lower pressuresthan reported before. The results are in excellentagreement with the reported high temperature, highpressure data.

In the second stage of the project one of us (A.Krozer) has studied hydrogen induced electronicchanges occurring during the formation of Mg -hydride (and of Ba - hydride) by UPS and XPS.Currently we are studying the resistivity changes inMg films as a function of hydrogen uptake. Theformer experiments were performed in Fribourg incollaboration with the group of Prof. L. Schlapbach40-42,47. The main findings are: There is aconsid-erable chemical shift (1.7 eV) of the Mg 1 s core levelupon hydriding. Ba 3d core levels show only minorchemical shifts. Part of Mg samples used remainedmetallic at the experimental conditions used, whileBa was hydrided fully at the same conditions. Thestructure of plasmon losses accompanying core lev-els of metallic Mg (and of metallic Ba) changesdrastically upon hydriding; the levels shift in energy,broaden (i.e. experience larger damping) and thenumber of losses decreases. The density of states atthe Fermi level of both Mg and Ba decreases drasti-

cally upon hydriding; thus confirming that the alka-line earth hydrides are insulators. The bandgap (asobtained from UPS measurements) is 3.4 eV widefor Mg and 2.2 eV wide for Ba. The valence band ofMg-hydride is centered around 5.4 e V and its FWHMis 2.4 e V. The valence band of Ba-hydride is centeredaround 4.3 eV and its FWHM is 2.9 eV.

The resistivity of Pd covered Mg films, hydridedin the equilibrium region of the phase diagram,increases linearly by approximately 0.5 pQcm/aL%H,in the region of concentrations [H/Mg] < 1. Irrevers-ible resistivity shifts are generated by cycling thehydriding dehydriding process. These shifts are gen-erally about a few percent of the total resistivitychange and are supposed to be related to hydrogenembrittlement.

F: Biomaterial Surfacesand Btocompatibllity

The biomaterial related research within the group iscarried as part of the Biomaterials Consortium, oneof 11 Interdisciplinary Research Consortia in Mate-rials Science and Materials Technology, funded byNUTEK/NFR. The Biomaterials Consortium con-sists mainly of our group at CTH and IngemarLundstrom's research group at Linköping Univer-sity, and also includes several projects in collabora-tion with groups from biology, medicine, and theclinical disciplines. Our own activities consist of thefollowing major projects:

F l : Preparation and propertiessurface oxides on Ti

Surface oxides on pure Ti and Ti6A14V alloy areprepared by different methods (thermal oxidation,electrochemical methods, plasma oxidation etc.)and analyzed by surface spectroscopies, electronmicroscopy, and STM/AFM. The objective is todevelop methods for producing Ti surfaces withsystematically varied properties (microstructure,roughness, chemical composition,...). The Ti sur-faces are used as model materials in biologicalexperiments where the influence of specific surface(oxide) properties on biological response is studiedby collaborators. Results from this project have ledto a broad surface spectroscopic and electron micro-scopic characterization of oxides prepared by differ-ent methods on pure Ti and Ti6A14V alloy ' .3-5,8 - 10,12,14,21,22,26 - 28,35,36,39,44,46,54,56,62,64,

66,68,76-78

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F2: Qowdtecnarge plasma preparationof surfaces

Glow discharge preparation is used as a method forcontrolled preparation and modification ofbiomaterial surfaces. One important goal is to mapout the surface properties of plasma prepared sam-ples as a function of plasma parameters (pressure,gas, current density, etc.). DC-plasmas are used forcleaning, oxidation, and chemical modification(nitriding, carbiding, etc.) of metal surfaces. Thepreparation is carried out in a UHV-equipment,which allows several preparation steps to be carriedout without any intervening exposure to uncon-trolled ambient. Results include:

• The current-voltage-pressure characteristics ofargon DC glow discharge with cylindricalgeometry has been studied.

• Procedures for controlled cleaning of Tisurfaces using an Ar glow-discharge have beenestablished.

• Oxides with different properties have beenprepared in 02-plasma.

• Different plasma prepared surfaces (oxides,nitrides, etc.) have been analyzed by surfacespectroscopies 62, electron microscopy, andSTM/SFM44.

Within this project we also intend to develop proce-dures for transferring UHV-prepared surfaces tobiological experiments without exposure to uncon-trolled ambient.

F3: Nano-and mlcrofabricated surfaces wrthcontrolled mlcroarchrtectureand/or chemical composition

In this project nano- and microfabrication methods(optical and electron lithography, PVD, dry and wetchemical etching, etc.) are used for preparing modelsurfaces for biological experiments. The objective isto develop surfaces with variations in micro-architecture and/or chemical composition, on a well-defined size scale. Materials used include Si, Ti, Al,V, Pt, and Au. This project utilizes the NanometerLaboratory at the Department of Physics, CTH.• Surfaces with well-defined microarchitecture

and/or variations in chemical composition onthe \tm scale have been produced. The surfaceshave been characterized by surface spectro-scopies, electron microscopy and STM/AFM66 and are used in a number of different bio-

logical experiments (cell cultures, bacterialadhesion)54

Future developments in this subproject will include:(i)extendingthe range of microfabricated surfaces toinclude structures and/or lateral chemical variationson the submicron scale, (ii) incorporation of the useof self-assembled monolayer techniques for prepar-ingsurfaceswithcontrolledchemical functionalities.

F4: Preparation, modHlcatlonand properties of biomaterial surfaces

In this project different preparation methods(electrochemical methods, PVD, glow dischargeplasma, nano- and microfabrication, self-assembledmonolayers) are developed for preparing sampleswith systematically varied surface properties. Thesurfaces are analyzed using different techniques(surface spectroscopy, electron microscopy, andscanning probe techniques), and subsequently usedin different biological experiments, which are mainlycarried out by collaborators. The aim of this projectis to find correlation between surface properties(structure and/or chemical composition) and bio-logical response. Some results from this subprojectare:• Ti implant, with different surface oxide proper-

ties (thickness, roughness, and microstructure),have been evaluated with respect to boneresponse at the Department of Anatomy, GU.Thicker and rougher surface oxides tend toheal in faster than smooth and thin ones %>. 68,

• Ti oxide surfaces have been used in plasmaprotein adsorption studies at the Laboratory ofApplied Physics, LiU. The different Ti oxidesurfaces show differences in protein adsorptionbehavior.

• Microfabricated surfaces, with controlledlateral variation in chemical composition(10x10 fim domains of Ti, Al, or V), have beenused in bacterial adhesion studies. Bacteriashow a binding preference in the order V > Ti>A154,66

• A method for preparing intact oxide-tissueinterface sections for TEM analysis has beendeveloped in collaboration with the Depart-ment of Anatomy, GU 22.


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F5: Model experiments ofbiomolecule«unace interactions

In this project the interaction of H2O and/or simplebiomolecules with solid surfaces is studied by sur-face science methods, in order to obtain an increasedunderstanding of the microscopic details of the inter-action between material surfaces and biological sys-tems. Initial experiments have been carried out onH2O and glycine (co)adsorption on an oxidized Tisurface, usingthermaldesorpnonspectroscopy(TDS)as the analytical technique. Results include:• Water adsorbs in at least three different bind-

ing states in the first monolayer on thepolycrystalline TiO2 surface, with desorptionpeaks in the range 350-170 K. The two peaksat higher temperature correspond to a coverage~O.l ML. and are believed to represent bond-ing and dissociation at defect sites (grainboundaries and oxygen vacancies).

• Multilayers of intact glycine molecules form atT<350 K. No intact glycine molecules desorbfrom the first monolayer, either because ofdissociative adsorption and/or thermal decom-position (T >500 K).

• Coadsorption induces only minor changes inthe desorption spectra of H2O and glycine,respectively, independently of the sequence ofadsorption. No change in glycine desorption isobserved. For H2O the high-temperature peakdecreases in intensity, with a correspondingincrease in the medium-temperature peak.

Future studies in this project will include: (i)spectroscopic (XPS and UPS) characterization ofthe adsorbed species, (ii) use of new surfaces (Pt, andsingle crystal TiO2) and additional amino acids, and(iii) incorporation of interesting coadsorbates, suchas atomic H and alkali atoms. Another aim is todevelop the TDS method as a "finger-print" tech-nique for characterizing biomaterial surfaces.

G: MlcronlcsThe objective of this project is to use the group'sexpertise about surfaces, surface processes, and sur-face preparation and analysis to prepare and investi-gate properties and processes of submicrometerparticles/structures particularly those of interest forcatalysis and biomaterials.

Gl: Sintering of highly dspersedPt on AJ203This study 37> 57- w was undertaken to primarilyinvestigate the stability of highly dispersed Pt parti-cles on porous AI2O3. The parameters of interestwere temperature and gaseous environment. Theeffects of the latter were striking. In noble gas orreducing atmospheres no sintering, i.e. no loss of Ptsurface area, was observed up to 700°C. In contrast,when the gaseous atmosphere contained O2 signifi-cant sintering was observed down to 500°C. Nitricoxide, NO, had an even larger effect on the sintering,which was then observed down to 200°C.

We have also developed a simple model whichhas been successful in describing the sinteringbehavior mathematically 52. The model is based onthat emission of an atom or molecule from a sup-ported catalyst particle is the rate limiting step insintering and that the stability of a particle dependson adsorbed gases and on the size of the particle.

Diffusion\

Emission

The results demonstrates the stability problem withnm structures on supports and how important theinfluence of various properties is for the stability.

G2: QCM measurements of waterand protein adsorption

This study 73«74 was initiated with the following longterm goals(i) to explore the possibility to use the QCM for

various protein adsorption studies,(ii)to investigate the influence of different surface

preparations on the protein adsorption behavior(2D or 3D adsorption, absolute coverage atdifferent protein solution and surface condi-tions etc.)

(iii) to eventually develop the QCM techniquefor kinetic studies in liquids.

So far steps (i) and (ii) have been realized. Using theimmersion-washing-drying technique developed forstudies of adsorption of silica sol particles we inves-tigated the saturation coverage of ferritin at differentferritin concentrations and on different surfaces. Themain results are: With increasing protein concentra-tion the saturation coverage increases monotonicallyuntil aclose packed layer of ferritin is approached forhydrophilic ozone cleaned Au surfaces. Step (iii) hasjust been initialized as a collaboration with the

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Department for Biophysics. We are building a liquidcell for the QCM which allows us to do simultaneousmeasurements of protein adsorption, capacitance,and laser induced electron transfer processes in situand in real time.

These results were compared to results obtainedwith oxidized Ti surfaces and with Au, prepared bypreadsorption of thiols. The results showed signifi-cant differences in surface coverage as the surfacestatus was changed. These exploratory measure-ments will be extended to other proteins and to moreprecisely defined surfaces.

G3: Biomaterial related micronics projectsThere is a substantial overlap between the micronicsproject and the biomaterials projects. Within themicronics program we have acquired an atomicforce microscopy (AFM) and scanning tunnelingmicroscopy (STM). These methods are excellenttools for characterizing topography of biomaterials44,68,72. The objective of this study is to, as preciselyas possible, characterize the topography of implantsand try to understand how it influences the biologicalresponse. As mentioned above AFM and STM havealso been used to characterize nano- and micro-fabricated surfaces. In the future we expect an evenstronger connection between the micronics and thebiomaterials programs.

References 1988-1992Ph.D. DissertationsAnalolc Krozer, CTH, "Hydrogen Adsorption on Pd-coalcdMg: Kinetics and equilibrium H/Mg ratios" May 26,1989

Dag Andersson, GU,"K+C12 Surface Chemilumincscencc:Molecuar Beam Scattering Apparatus, Spectra and Kinet-ics"; Nov 10.1989

Jukka Lausmaa, GU, "Surface Oxides on Titanium:Preparation, characterization and biomaterial applications,"June 4,1991

Peter Sjövall, CTH, "Adsorption, Dcsorption and Reactionof Oxygen Containing Molecules on Clean and PotassiumCovered Carbon Surfaces," May 21,1992

Ucenclate DissertationsMikael Ask, GU, "Composition and Structure of SurfaceOxide Films on Ti6AI4V," May 31,1988

Jukka Lausmaa, GU, "Surface Preparation and Analysi ofTitanium Implant materials," June 8,1988

Mohammad Fassihi.GU, "Catalytic Oxidation of H2 on Pt,"June 1,1991

Diploma Work, CTHJoakim Ramberg, "Testing of an Open Polymer High-Voltage Cable Ending," 1988

Bengt Olsson, "Influence of Mcthanol on the TribologicalBehaviour of Steels," 1988

Magnus Hurd, "Kinetic Modelling of 2NO + 2H2 & N2 +2H2O on Palladium Surface," 1989

Göran Rådegran, "Preparation of Thin Oxide Windows onTitanium forTEM Analysis and Protein Adsorption," 1989

Johan Landin, "Preparative Techniques for the Study ofProtein Adsorption," 1989

Martin Dahlberg, "Evaluation of Fuel Sensors for AlcoholContent measurements," 1990

Johan Strömqvist, "Numerical Calculations of Ion Trajecto-ries Inside a Quadrupolc Mass Spectrometer Analysis ofDetection Efficiency," 1991

Per Hovcrstam, "A Computerized Pulse Counting Detec-tion System for Mass Spcctrometry - Installation,Syncronization, and Testing," 1991

Gudrun Spicss, "Sulphur Storage and Hydrogen SulphideRelease from Car Aged Catalysts," 1992

Project Work at GULars-Olof Torbcrntsson, "Calcium Doping of Anodic OxideFilms on Titanium, 1989

Claes Åkerlund, "Production and Size manipulation ofAlkali Clusters on Alkali Halidc Surfaces," 1991

Patrik Johansson, "Theoretical and Experimental Studies ofa DC Glow Discharge Plasma," 1992

Books1. "Preparation, Surface Spcctroscopic and Electron

Microscopic Characterization of Titanium ImplantMaterials" J. Lausmaa, B. Kascmo, U. Rolander, L.M.Bjurstcn, L.E. Ericson, L. Rosander and P. Thomscn inSurface Characterization of Biomaterials B.D. Ratncr,Editor. 1988,Elscvicr: New York. p. 161-174.

2. "Improved insight into catalytic reactions by kineticmodelling and LIF detection of intermediate species"E. Fndell, B. Hcllsing, S. Ljungström, T. Wahnström,A. Rosén and B. Kasemo in Laser Spcctroscopy IXM.S. Fold, A. Mooradian, and J.E. Thomsas, Editor.1989, p. 424.


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3. "Preparation and analysis of Ti and alloyed Ti surfacesused in the evaluation of biological response" J.Lausmaa, M Ask, U. Rolander and B. Kasemo inBiomaterials and biomedical devices J.S. Hanker andB.L. Giammara, Editor. 1989, Material ResearchSociety: p. 647-653.

4. "The biomaterial-tissue interface and its analogues insurface science and technology" B. Kasemo and J.Lausmaa in The bone-biomaterials interface J.E.Davies, Editor. 1991, University of Toronto Press:Toronto, p. 19-32.

5. B. Kasemo and J. Lausmaa. Biomaterials from asurface science perspective, in Symposium on SurfaceAnalysis of Biomaterials. 1988., Ann Arbor Michigan,June 21-24,1987: Elsevier, Amsterdam.

Journal Articles6. "Kinetic model study of OH desorption during H2O

production on Pi" B. Hellsing and B. Kasemo, Chem.Phys. Leu. 148,1988,465.

7. "The island model of a Langmuir Hinshelwoodreaction" B. Hellsing and V.P. Zhdanov, Chem. Phys.Leu. 147,1988,613.

8. "Biomaterial and implant surfaces; on the role ofcleanliness, contamination and preparation procedures"B. Kasemo and J. Lausmaa, J. Biomed. Mater. Res.;Applied Biomaterials 22.1988,145-158.

9. "Biomaterials and implant materials: A surface scienceapproach" B. Kasemo and J. Lausmaa, The Interna-tional Journal of Oral & Maxillofacial Implants 3,1988,247-259.

10. "Surface spectroscopic characterization of the separa-tion of plastic-embedded tissue and titanium implants"J. Lausmaa and L. Linder, Biomaterials 9,1988,277-280.

11. "Weighing monolayers of colloidal silica particles witha quartz crystal microbalance" S.-A. Nordin and B.Kasemo, Progress in Colloid & Polymer Science 76,1988,51.

12. "Preparation and Surface Spectroscopic Characteriza-tion of Oxide Films On Ti6A14V" M. Ask, J. Lausmaaand B. Kasemo, Appl. Surface Sci. 35,1988-89,283-301.

13. "Electronic mechanism for alkali promoted oxidationof semiconductors" B. Hellsing, Phys. Rev. B 40,1989,3855.

14. "Ultrastructural Differences of the Interface ZoneBetween Bone and TOA14V or Commercially PureTitanium" C. Johansson, J. Lausmaa, M. Ask, H.-A.Hansson and T. Albrektsson, J. Biomed. Mater. Res.11,1989,3-8.

15. "Equilibrium hydrogen uptake and associated kineticsfor the Mg-H2 system at low pressures" A. Krozer andB. Kasemo, J. Physics. F. Condensed Matter 1,1989,1533.

16. "Determination of the activation energy for OHformation in the H2+O2 reaction on polycrystallineplatinum" S. Ljungström, E. Fridell, B. Hellsing, T.Wahnström, B. Kascmo and A. Rosén, Surf. Sci. 223,1989.L905-L912.

17. "An experimental study of the kinetics of OH and H2Oformation on Pt in the H2+O2 reaction" S. Ljungström,B. Kasemo, A. Rosén, T. Wahnström and E. Fridell,Surf. Sci. 216.1989,63.

18. "Oxygen storage capacity of noble metal car exhaustcatalysts containing Ni and Ce" P. Lööf, B. Kasemoand K.-E. Keck, Journal of Catalysis 118,1989,339-348.

19. "A Surface Spectroscopic Study of Reaction Layers inAlcohol-Fuelled Diesel Engines" L. Mattsson, H.Abramsson, B. Olsson, H. Ekberg, P.H. Nilsson, G.Wirmark and B. Kasemo, Wear 130,1989,137.

20. "Unusual kinetics in Mg/Pd sandwiches, studied byhydrogen profiling and quartz crystal microbalancemeasurements" J. Rydén, B. Hjörvarsson, T. Ericsson,E. Karlsson, A. Krozer and B. Kasemo, J. LessCommon Metals 152,1989,295.

21. "Microstructure and morphology of surface oxide filmson Ti6AMV" M. Ask, U. Rolander, J. Lausmaa and B.Kascmo, J. Mäter. Res. 5,1990,1662-1667.

22. "Method for ultrastuetural studies of the intact tissue-metal interface " L.M. Bjurstcn, L. Emanuclsson, L.E.Ericson, P. Thomsen, J. Lausmaa, L. Mattsson, U.Rolanderand B. Kasemo, Biomaterials 11,1990,596-601.

23. "Determination of the activation energy for OHdesorption in the catalytic H2 + O2 reaction on Pi" E.Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A.Rosén and T. Wahnström, Vacuum 41,1990,732.

24. "Hydrogen uptake by Pd-coated Mg; absorptiondecomposition isotherms and uptake kinetics" A.Krozer and B. Kasemo, J. Less Common. Metals 160,1990,323-342.

25. "Hydrogen interaction with Pd covered Mg-equillibrium uptake and kinetics at low pressure andtemperature" A. Krozer and B. Kasemo, Journal of theLess Common Metals 160,1990,323.

26. "Surface Spectroscopic Characterization of TitaniumImplant Materials" J. Lausmaa, B. Kasemo and H.Mattsson, Applied Surface Science 44,1990,133-146.

27. "Multi-technique surface characterization of oxidefilms on electropolishcd and anodically oxidizedtitanium" J. Lausmaa, B. Kascmo, H. Mattsson and H.Odelius, Appl. Surface Sci. 45,1990,189-200.

28. "A Surface Spectroscopic Study of Nitrogen-ImplantedTi and Ti6AI4V Wear against UHMWPE" J. Lausmaa,T. Röstlund and H. McKcllop, Surf. Interface Anal. 15,1990,328-336.

29. "NO2 adsorption on graphite at 90 K" P. Sjövall, S.K.So, B. Kascmo, R. Franchy and W. Ho, Chem. Phys.Lett. 171,1990,125-130.

30. "Laser-induced fluorescence studies of rotational slatepopulations of OH desorbed in the oxdidau'on ofhydrogen on Pt" T. Wahnström, S. Ljungström, A.Rosén and B. Kasemo, Surf. Sci. 234,1990,439-451.

31. "Hydroxyl desorption from plalimum in the catalyticformation and decomposition of water" E. Fridell, B.Hcllsing, B. Kasemo, S. Ljungström, A. Rosén and T.Wahnström, J. Vac. Sci. Tech. A 9,1991,2322.

122 THE CENTRE FOR

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32. "A gas inlet system for quantitative massspcctroscopy" J. Hall, S. Lundgren, K.E. Keck and B.Kascmo, Int. J. Ion and Mass Spcctromctry 108,1991,1-21.

33. "Measurement of position-dependent detectionefficiencies for two quadropole mass spectrometerswith electron-impact ion sources" J. Hall, M. Rinncmo,I. Zone and B. Kasemo, Rev. Sci. Instr. 62,1991,1-6.

34. "Reaction scheme for catalytic oxidation of hydrogenon platinum" B. Hcllsing, B. Kasemo and V. Zhdanov,Journal of Catalysis 132,1991,210-228.

35. "Wear of ion-implanted pure Ti and Ti6A14V alloyagainst UHMWPE" J. Lausmaa, T. Rostlund and H.McKcllop, Surf. Eng. 7,1991,311-317.

36. "Wear of ion-implanted pure titanium and Ti6A14 Valloy against UHMWPE" J. Lausmaa, T. RösUund andH. McKellop, Surface Eng. 7,1991,311-317.

37. "Influence of Ceria on the Interaction of CO and NOwith Highly Dcspersed Pi and Rh" P. Lööf, B.Kascmo, S. Andersson and A. Frestad, J. Catalysis 130,1991,181-191.

38. "Up-hill diffusion and hydrogen-hydrogen interactionin Pd-Pt alloys'' A. Mällo and A. Krozcr, Journal of theLess Common Metals 167,1991,305.

39. "Preparation of ultra-thin oxide windows on titaniumfor TEM analysis" G. Rådegran, J. Lausmaa, U.Rolandcr, L. Mattsson and B. Kasemo, J. El.Microscopy. Techn. 19,1991,99-106.

40. "Mg on Mg(l 11): the formation of local order ob-served by photoclectron diffraction" R. Fascl, J.Osterwalder, A. Fischer, A. Krozer and L. Schlapbach,Physical Review Letters 1992,

41. "Plasmon losses in thin Mg films - a new method forthickness determination" A. Fischer, A. Krozcr and L.Schlapbach, Physical Review B 1992,

42. "Mg/Pd and Ba/Pd interfaces and without hydrogen"A. Fisher, A. Krozcr and L. Schlapbach, SurfaceScience 269/270,1992,737.

43. "Reaction of fast CO molecules with CO, NO, or 02presorbed on Pt(l 11) surface; a search for Elcy-Ridcalreaction mechanism" J. Hall, I. Zoric and B. Kasemo,Surface Science 269/270,1992,460-464.

44. "Scanning Tunneling Microscopy of Oxidized Tita-nium Surfaces in Air" H. Olin, B.O. Aronsson, B.Kascmo, J. Lausmaa and M. Rodahl, Ultramicroscopy42-44,1992,567-571.

Accepted for publication45. "Vibrational spectra of KOx complexes on graphite"

D.V. Chakarov, P. Sjövall and B. Kascmo, to appear inSurface Science

46. "A histomorphomctric study of the bone tissue re-sponse to untreated and nitrogen-ion implanted c.p.titanium and Ti6A14V" C.B. Johansson, J. Lausmaa, T.Rostlund and P. Thomscn, to appear in J. Maler. Sci..Materials in Medicine

47. "Hydrogen diffusion in thin Mg films studied by XPS"P. Spatz, H. Aebisher, A. Krozer, A. Fischer and L.Schlapbach. to appear in Zcitscrift fur PhysikalischcChcmicNF

Submitted manuscripts48. "Replacement of 0 2 by CO on Pt( 111) surface" C.

Åkerlund, I. Zoric, J. Hall and B. Kascmo, submitted toJournal of Chemical Physics 1992.

49. "The reaction between CI2 and evaporated K films. II.Surface chcmilumincsccncc and negative particleemission intensities vs. CI2 exposure" D. Anderssonand B. Kascmo, submitted to Surf. Sci. 1992.

50. "The reaction between CI2 and evaporated K Films. I.Mass uptake rates vs. C12 exposure for various filmthicknesses" D. Andersson, B. Kascmo and A. Mällo,submitted to Surf. Sci. 1992.

51. "The interaction of potassium with oxygen on graphiteas studied by high resolution electron energy lossspcctroscopy and thermal dcsorption spcctroscopy" wD.V. Chakarov, P. Sjövall and B. Kascmo, submittedto Journal of Chemical Physics 1992.

52. "Catalytic ignition in the hydrogen-oxygen reaction onplatinum" M. Fassihi, V.P. Zhdanov, M. Rinncmo, K.-E. Keck and B. Kascmo, submitted to Journal ofCatalysis 1992.

53. "OH formation in H2O and H2O + Oa mixtures" E.Fridell, B. Kascmo and A. Rosén, submitted toLangmuirl992.

54. "Site-specific adhesion of S. cpidcrmidis in Ti-Al-Vmetal systems" B.L. Gabriel, J. Gold, A.G. Grisiina, B.Kascmo, J. Lausmaa, B. Nilsson, C. Mroczck and Q.N.Myrvik, submitted to Science 1992.

55. "Layer by layer growth of 5-50 nm silica-sol particlesstudied by quartz crystal microbalance measurements"A. Krozcr, S.A. Nordin and B. Kascmo, submitted toJournal of Colloid and Interface Science 1992.

56. "Bone healing around titanium implants with differentsurface oxides" C. Larsson, P. Thomscn, J. Lausmaa,B. Kascmo and L.E. Ericson, submitted to 1992.

57. "A TDS and TEM study of the influence of differentgases on the sintring rate of nm Pt-particles on AI2O3"P. Lööf, B. Stenbom, H. Norden and B. Kascmo,submitted to Journal of Catalysis 1992.

58. 'Time and space resolved measurements of gascompostion and temperature in catalytic reactions.Equipment design and results for H2 oxidation and Pi"S. Lundgren, K.-E. Keck and B. Kascmo, submitted toJournal of Catalysis 1992.

59. "A TPS study of oxygen, water, and carbon dioxidecoadsorplion with potassium on graphite" P. Sjövalland B. Kascmo, submitted to Surface Science 1992.

60. "Thermal desorption from multiple stages of potassiumintercalated graphite" P. Sjövall and B. Kascmo,submitted to Physical Review Letters 1992.


SURFACE PHYSICS

61. "Kinetics of the interface hydride formation by Pd-coatcd Mg" VP. Zdhanov, A. Krozcrand B. Kasemo,submitted to Physical Review B 1992.

Manuscripts in preparation62. 'Titanium oxides formed in a DC glow-discharge

plasma" B.-O. Aronsson, J. Lausmaa and B. Kasemo,1991 (manuscript in preparation).

63. "A molecular beam scattering apparatus for surfacechcmiluminesccncc studies. Preliminary results foremission of excited K atoms" D. Andersson, L.Hellberg and B. Kasemo, 1992 (manuscript in prepara-tion).

64. "The behaviour of inflammatory cells close to theimplant surface studied ultrastructurally during the firstweek after insertion of titanium and polytetrafluoro-ethylcne implants in soft tissue" L.E. Ericson, P.Thomson, L.M. Bjursten, J. Lausmaa and B. Kascmo,1992 (manuscript in preparation).

65. "A simple model of sintering of supported catalystparticles in various atmospheres" M. Fassihi, P. Lööfand B. Kascmo, 1992 (manuscript in preparation).

66. "Model systems for studying site-specific bacterialadhesion in Ti-Al-V metal systems" J. Gold, B.L.Gabriel, B. Kascmo, J. Lausmaa, A.G. Gristina, C.Mroczck and Q.N. Myrvik, 1992 (manuscript inpreparation).

67. "Kinetics of interface hydride formation in Pdprecovered Mg films" A. Krozcrand B. Kasemo, 1992(manuscript in preparation).

68. "Bone tissue response to surface modified implants inrabbit. Part 1. Studies on clcctropolishcd titaniumimplants with different oxide thicknesses" C. Larsson,P. Thomsen, J. Lausmaa, B. Kasemo, L. Ericson andM. Rodahl, 1992 (manuscript in preparation).

69. "CO disproportionation on supported noble metal carexhaust catalysts" P. Lööf and B. Kascmo, 1992(manuscript in preparation).

70. "CO disproportionation on cobolt" S. Lundgren, B.Kascmo and K.-E. Keck, 1992 (manuscript in prepara-tion).

71. "On the critical condition for catalytic ignition; H2/O2on Pt" M. Rinnemo, M. Fassihi and B. Kascmo, 1992(manuscript in preparation).

72. "Charcterization of natural oxide and electropolishcdtitanium implants with different oxide thickesscs withAFM" M. Rodahl, 1992 (manuscript in preparation).

73. "Water adsorption measuremcts of various surfaces bya quartz crystal microbalancc" M. Rodahl and B.Kasemo, 1992 (manuscript in preparation).

74. "Quartz crystal microbalance studies of ferritinadsorption onto various surfaces" M. Rodahl, A.Krozcrand B. Kasemo, 1992 (manuscript in prepara-tion).

75. "Photodesorption of NO2 from graphite at 90 K" P.Sjövall, W. Ho, B. Kascmo and S. So, 1992 (manu-script in preparation).

76. "The ultrastructure of the intact interface betweentissue and implants of aluminium, gold, titanium andzirconium" P. Thomsen, L.M. Bjursten, J. Lausmaa, B.Kasemo and L.E. Ericson, 1992 (manuscript inpreparation).

77. "Controlled microsurface preparation for analysis ofcell-implant interactions" P. Thomsen, J. Lausmaa, E.-K. Andersson and B. Nilsson, 1992 (manuscript inpreparation).

78. "Morphomctry of the interface between bone and gold,titanium and zirconium implants" P. Thomson, J.Lausmaa, L. Scnncrby, L.M. Bjursten, B. Kasemo andL.E. Ericson, 1992 (manuscript in preparation).

124 THE CENTRE FOR

Clusters andfine particlesMolecular Physics 126Engineering Chemistry 139


Molecular Physics

Research SummaryThe research activities within our group consist of atheoretical programme for investigations of theelectronic structure of atoms, free molecules, atomicclusters and surfaces and an experimental pro-gramme for studies of clusters, fullerenes and prob-lems in surface science and catalysis using laserspectroscopy. Qose interaction between the experi-mental and theoretical research programmes is em-phasized.

The theoretical research involves both the devel-opment and the application of computational meth-ods for non-relativistic and relativistic calculationsfor molecules, clusters and fullerenes based on theLocal Density Approximation. X-ray AbsorptionNear Edge Structure (XANES) and photoionizationcross-sections have been evaluated for small metalclusters. The electronic structure, ionization ener-gies, electron affinities, absorption spectra, linearand non-linear optical properties have been calcu-lated for Ceo and COO doped with different atoms.

A scheme has been developed for evaluation ofthe electronic structures of the bulk, stoichiometricand non stoichiometric surfaces of ionic crystalssuch as CaF2 and BaF2 using small clusters embed-ded in an external crystal potential. This scheme hasbeen used for interpretation of laser induced en-hanced electron and ion emission and SHG genera-tion for these surfaces.

Laser-induced fluorescence (LIF) is used for theidentification and characterization of intermediatespecies in catalytic reactions, and particularly to-wards studies of the reaction intermediate, OH, in theoxidation of hydrogen and decomposition of wateron different transition element catalysts, such as Pt,Pd, Rh. Ir and Ni. Measurements of the yield of OH(from LIF) and the rate of H2O production (fromcalorimetry) have been combined with kinetic modelcalculations by Prof. Bengt Kasemo in the ChemicalPhysics Group.

A new set-up for production of clusters of anysolid elements with the laser vaporization methodhas been built and used for measurements of the

reactivity of clusters of Fen, CON and CUN clusters,with N=10-55. An electric arc evaporation set up hasalso been built for macroscopic production offullerenes and a time of flight (TOF) spectrometerfor analysis of solids, surfaces, gases and volatileliquids using ion sputtering and laser ionization.

AddressDepartment of PhysicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone +46 31 772 3295Fax+46 31 772 3496

StaffSenior Members:Arne RosénJohn Persson

Graduate Students:Mats AnderssonAlf-Peter ElgErik FridellFredrik GudmundsonHenrik GrönbeckLotta HolmgrenJohan MellqvistErik WestinBo WästbergDaniel Östling

Technical staff:Leif JohanssonHeinrich Riedel

Secretary:Eva Eriksson

professorPhD April91,UCLA

civ.ing.fil kand.fil.lic.civ.ing.fil. kand.civ.ing.civ.ing.tekn.lic.civ.ing.fil. kand.

engineerchemist (part time)

(Dart time)

126 THE CENTRE FOR

MOLECULAR PHYSICS

Major InstrumentationContact peisons:

Ame Rosén tel 031-7723295Leif Johansson tel 031 -7723297• High vacuum system for studies of catalytic

reactions at pressures of 10*3 -1 Torr usingLIF and mass spectrometry.

• UHV-system with AES and LEED for studiesof surfaces of single crystals, catalytic reac-tions using LIF, mass spectrometry, SHG, SFGandDFG.

• Excimer laser, Lambda Physik EMG102(XeCl) Two dye lasers, Lambda PhysikFL2002E

• Excimer laser, Lambda Physik LPX2101(ArF)

• Nd: YAG laser ns, ps, Quantel InternationalYG 671 C-10 Dye laser ns, TDL 51, Dye laserps, PTL 10, IR-generation, These lasers areshared with Lars Walldén

• TOF spectrometer for laser ionization massspectrometry

• Set-up for production and spectroscopy of freeclusters

• CCD camera Spectroscopy Instruments• Nd: YAG laser ns, Continuum YG 661-10• Workstations SUN SLC and ELC• Different MAC and IBM computers

Financial SupportThe Swedish Natural Science Research Council

(NFR)The National Swedish Board for Technical Devel-

opment (NUTEK)The Swedish Board for Technical Development

(STUF)The Swedish Council for Planning and Coordina-

tion of Research (FRN)Material Science Consortium "Clusters and

Ultrafine Particles" (NFR/NUTEK)Swedish Research Council for Engineering

Sciences (TFR)National Energy Administration (STEV)Ema and Victor Hasselblad FoundationKnut and Alice Wallenberg FoundationCarl Trygger's FoundationOllie and Elof Ericssons Foundation for Scientific

Research

Wilhelm and Martina Lundgren's ScientificFoundation

Adlerbertska Foundation

Major Reids of ResearchA: Calculations for free molecules, clusters and

surfacesparticipants: Henrik Grönbeck, Ame Rosén,Erik Westin, Bo Wästberg and Daniel Östlingcollaborators: Sven Larsson, Manuell Braga,Phys Chem CTH., Don Ellis, NortwesternUniversity Evanston Illinois USA , BengtLindgren, Uppsala University, Uppsala.,Burkhard Fricke, Dirk Heinemann, Universityof Kassel, Kassel, Germany, Eckart Matthias,Freie Universität Berlin, Germany, PeterApell, Dept of Theoretical Physics CTH

B: Laser spectroscopic studies of catalytic reac-tions and kinetic modellingparticipants: Alf-Peter Elg, Erik Fridell,Fredrik Gudmundson, and Arne Roséncollaborators: Bo Hellsing and Bengt Kasemo,Chemical Physics, Dept. of Applied Physics,CTH/GU.

C: Laser Ionization Mass Spectrometryparticipants: Mats Andersson, John Perssonand Arne Rosén.

D: Experimental Studies of Clustersparticipants: Mats Anderssoi, John Perssonand Arne Roséncollaborators: Participants in the Consortium"Clusters and Ultrafine Particles", WolgangKrätschmer, Max Planck Institut Heidelberg

E: Calculations for atomic systemsparticipants: Arne Roséncollaborators: Burkhard Fricke, University ofKassel, Kassel, Germany.

F: Related projectsparticipants: Johan Mellqvist and Ame Roséncollaborators: Bo Galle, Swedish Environ-mental Research Institute, Håkan Axelsson andAnnika Johansson, Vattenfall, EngineeringAB, Göteborg and Älvkarleby, Svante Höjer,


MOLECULAR PHYSICS

Dept of Optoelectronics CTH , Magne AlpstenDept of Radiation Physics GU, Olle LarköDept of Dermatology Sahlgrenska HospitalGU

Research ProjectsA: Calculations for free molecules,clusters and surfaces

The calculations for free molecules, clusters andfullerenes performed within our group are mainlybased on the local density approximation, LDA,which implies that the exchange and correlationparts of the electron-electron interaction are replacedwith a local potential. The calculations are orientedtowards studies of electronic, linear and non-linearoptical properties. The molecular wavefunctionsand potentials evaluated with our programs havealso been used as input to other programs for evalu-ation of XANES spectra and photo-ionization crosssections for small clusters. The computer programsdeveloped for studies of the electronic structure offree molecules, and small clusters are also verysuitable for studies of problems related to surfacescience and catalysis. Of particular interest is the factthat our computational methods can be used forstudies of surfaces of metals and insulators includingmetal clusters and molecules adsorbed onto thesurfaces, which are of great interest in basic surfacescience and applied catalysis.

A l : Development of computational methodsThe molecular wavefunctions are of Molecular Or-bital Linear Combination of Atomic Orbital, MO -LCAO, form with atomic basis functions on a nu-merical grid generated with an atomic self-consist-ent-field (SCF) program for free atoms or ions. Thematrix elements in the secular equation are evaluatedby use of three dimensional numerical integrationmethods as the Discrete Variational Method, DVM,and more recently a method developed by P. M.Boerrigter, G. Te Veide and E. J. Baerends (Int. J.Quant. Chem. 3_3_,87(1989)). The multiple scatter-ing, MS, method has been generalized for generalnon-muffintin potentials of molecules with an arbi-trary geometrical shape and tested in calculations onH2+and CO( 1,2). Furthermore, acomputerprogramfor generation of symmetry adapted basis functions

has been developed for 36 finite double point groups(6) and used to study the electronic structure ofelement 105 (7).

In recent years, there have been an increasinginterest in the use of numerical methods for the self-consistent solution of the Schrödinger and Diracequations for molecules as a complement to standardbasis set oriented approaches i.e. MO-LCAO. Wehave used the finite element method (FEM) forcalculations of potential energy curves for diatomicmolecules within the restricted Hartree Fock Slater(HFS) approximation using the FEM method incalculations of spin polarized HFS (3) and restrictedHartree Fock (HF) potentials (4). The potentialenergy curves are determined with a numericalaccuracy of better than 10^a.u. i.e. 0.03 meV. Thesetype of very accurate potential energy curves havealso been used for optimization of basis-sets used inMO-LCAO calculations (5).

A2: Electronic structure for free molecules,clusters, fulllerenes

The electronic structures of small cobalt and nio-bium clusters, Coi.j3t (8), Nbi-n (9,10) have beencalculated within the local spin density approxima-tion using the LCAO method. The possibilities ofusing XANES for determination of the geometricalstructure of clusters has been tested in calculations oftheoretical K-edge XANES cross sections for somedimers and trimers as Fe2, Ni2, M3, Mn2 and C02(11,12). The calculated cross-sections for the dimerspredict broad resonant structures atthe threshold andweak Is transitions to unoccupied valence orbitalsgiving a shoulder at the threshold. The resonancestructure at the threshold of Ni3 appeared to besensitive when varying the apex angle of the trimersfrom a linear shape to an equilateral triangle.

In spite of very successful research for studies ofexperimental ionization potentials, electron affini-ties, abundances for neutral and negatively chargedclusters asdetermined from mass spectrometry meas-urements on supersonic cluster beams, very little isknown about the nature of the photoionization crosssections of such clusters. We have in to order toanalyze such problems performed some calculationsof the photoionization cross section forclusters of Naand K and have evaluated the U V and especially 5-15 eV photoelectron cross sections of Na2-s and K2.K clusters (13-15) using the continuum multiple-scattering method combined with starting potentials

128 THE CENTRE FOR

MOLECULAR PHYSICS

calculated with our molecular programs using theLDA method. The most striking feature of thesecalculations is the resonant behavior of all Kx clus-ters between 5-10 eV and the absence of resonancesfor the Nax clusters. These resonances could beunderstood as shape resonances i. e. trapping of theoutgoing photoelectron by a potential barrier in theeffective potential.

The development of an efficient method [W.Kratschmer, L.D. Lamb, K. Fostiropoulos and D.R.Huffman, Nature 347 (1990) 354 - 358. ] for largescale productionof the early discoveredfootball-likecarbon cluster COO a l s o referred to as"Buckminsterfullrene" [ H. Kroto, J.R. Heath, S.C.O'Brien, R.F. Curl, and R.E. Smalley, Nature 318(1985) 162 - 163 ] has during the last two yearsinitiated a boom of experimental and theoreticalstudies. Our earlier predictions from 1987 (16) ofoptical transitions for Q j has been found to becrucial when Krätschmer et al developed the electricarc evaporation technique for macroscopic methodfor production of fullerenes, (see project D2). Thesecalculations have been extended to the evaluation ofthe optical spectra for the negative and positive ionsof COO and for polycyclic aromatic hydrocarbonsPAH (17,18). Furthermore, many of our earlierpredictions of ionization energies and electron af-finities for Qo have been found to be in goodagreement with recent UPS measurements. Calcula-tions have also been done for the neutral, positivelyand negatively charged clusters of Qo and metalcontaining clusters as MQo .where M= La, Li, Na,K, Rb, Cs, Ca, Sc, and for K2Q0 and K3Q0 (22-27).

A3: Electronic structure of solids and surfacesThe electronic structure and bonding processes formolecules adsorbed on surfaces and especially COadsorption on Ni, C1. Pd and Pt surfaces has earlierbeen analyzed. We have more recently focussed ourwork on analyzing the composition of the 2p* stateof CO adsorbed on the Pt(llO) surface (28).

An overview of our method for evaluation of theelectronic structure of surfaces of ionic crystalssurfaces is given in the fig. 1 and discussed in (30-35).Briefly, a local molecular cluster is embedded in anexternal potential derived from frozen ionic chargedistributions and a sufficient number of exteriorpoint ions (33,36). Molecular eigenvalues, wave-functions and charge densities are then obtained by

SURFACE CLUSTERS (MX2 13 atoms)

M centred X centred

Surface plane

Crystal cross section Point ions

Figure 1. Geometry oi the planar clusters used torepresent the (111) surface cf CaF2 and BaF2.Our model of the crystal ^rvironment isschematically shown. M = Ca or Ba and X = F.

self consistent field calculations. This technique hasbeen used in analysis of the electronic structure ofdifferent models of ionic surfaces of CaF2 and BaF2and in particular of how the non-stoichiometry influ-ences the local surface electronic structure and hencethe interaction mechanisms with exterior distur-bances. We have so far discussed laser interaction(30-35) and compared our results with experimentalEELS data for CaF2. The study of laser inducedprocesses at ionic crystal surfaces also include analy-sis of second harmonic generation, SHG, where wehave worked out phenomenological expressionsgoverning this process (36) and evaluated the wave-length dependent hyperpolarizabilities (37).

A4: Studies of linear and nonlinear opticalproperties for fullerenes

In this project, single particle wavefunctions deter-mined from ground state LDA calculations forfullerenes are used for evaluation of dipole matrixelements which combined with a sum over stateapproach yield linear and non-linear microscopicpolarizabilities gO) and gO), respectively. Lorentzlocal field factors, as well as a simple RPA typecorrection are introduced to facilitate comparisonwith the dielectric function e(w) determined fromfilms of C«). Reasonable agreement is found with


MOLECULAR PHYSICS

results from linear optical response experiments i.e.ellipsometric and EELS measurements on C n insolid or solution form after screening has beenincluded as obtained from the RPA (38-41). SecondHarmonic Generation, SHG, Third Harmonic Gen-eration, THG, and Degenerate Forward Mixing,DFWM, experiments yield values close to theunscreened result, while invoking a RPA screeningresults in a non-resonant value about 2 orders ofmagnitude lower than most experiments.

A5: Studies of surface plasmons in fullerenesStudies of the U V absorption and EELS experimentshave shown very strong resonances which havesimilarities to the collective resonances found ingraphite. We have in cooperation with Peter Apellmodeled the electronic structure of Qo as a sphericalshell of electrons and used classical electrodynamictheory for discussing the collective resonances(42,43). A very good agreement has been found withEELS experiments. Work is now in progress toapply the same formalism to the recently discovered"carbon onions" and "carbon tubes". These newmaterial are spherical and cylindrical multilayers ofgraphite and we expect that our predictions of opticalproperties will be valuable in the the characterizationof these new types of carbon species.

B: Laser spectroscopic studies ofcatalytic reactions and kinetic modelling

This project in catalysis is focussed on studies ofcertain model reactions and identification of possi-ble intermediate species, which are probed using thelaser induced fluorescence, LIF, technique. Infor-mation on the existence and yield of intermediatespecies in catalytic reactions gives a better under-standing compared with when only the reactants andfinal product(s) are followed. A molecule that ispresent in all oxidation of hydrocarbon, and prob-ably important in initiating combustion in catalyticburners via desorption from the catalytic wall mate-rial into the gas-phase, is the OH-radical. The experi-mental results are correlated with kinetic modelcalculations done in the Chemical Physics group atCTH.

B l . Studies of OH, H2O formation and H20decomposition on model catalysts as Pt,Pd, Rh, Ir

We have in this project focussed our research on astudy of the simplest heterogeneous catalytic model-reaction, that includes OH-radicals, which is theoxidation of hydrogen to water on a metal catalyst.The OH radical is formed at the surface of thecatalyst when molecular hydrogen and oxygen firstdissociate at the surface and then recombine to OH,which is then consumed in the water formation. If thecatalyst is kept at a high temperature (> 1000 K) thereis a small possibility that the OH radicals desorbfrom the catalyst before beingconsumed in the waterproduction. The OH radical has been detected andcharacterized with respect to its yield, activationenergy for desorption and rotational energy using thelaser-induced fluorescence technique (LIF). Sincethe oxidation of hydrogen is exothermic the dissi-pated chemical energy can be utilized to determinethe water formation rate (microcalorimetry). Bycombing the two techniques, LIF andmicrocalorimetry, we thus follow a short-lived inter-mediate radical as well as the final product.

We perform the experiments in two differentvacuum chambers: a high-vacuum chamber for ex-periments in the pressure range * mTorr to 10 Torrand a newly constructed UHV- system, containingLEED and AES for surface analysis, for studies withsingle crystals at lower pressures.

Studies of the H2 + O2 —> H2O reaction onpolycrystalline Pt foils have shown that H2O forma-tion proceeds mainly via OH + H —> H2O at hightemperature and that the OH-Pt bond strength isabout2.0eV.Theexperimentally obtained resultsonH2O formation and OH desorption as a function ofpressure, surface temperature and gas mixture arewell described by a kinetic model (47,48 and B.Hellsing, B. Kasemo and V. P. Zhdanov, J. Catal.,132,210 (1991)). Besides the kinetic and energeticaspectsof catalytic reactions, achieved in the alreadymentioned measurements, we have also studied thepopulation of different rotational levels of thedesorbed OH and OD radicals or the rotationaltemperatures of desorbed OH (48). Extrapolatingthese data to zero pressure showed that the rotationalenergy distribution is a Boltzmann distribution witha rotational temperature of about 80 % of the catalysttemperature for OH and 96 % for OD. At higherpressures a strong cooling of the rotational tempera-

130 THE CENTRE FOR

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ture wasobservedduetocollisions with thereactantsand water vapor.

In order to understand this reaction further and totest the kinetic models the reaction H2O +1/2 O2——> 2OH, i.e. decomposition of water to OH radi-cals, has been studied (50,53,57). Gaseous waterflows into the vacuum system and the OH desorptionis monitored at different total pressures, differentpartial pressures of the water and oxygen and differ-ent catalyst temperatures on Pt. The significant andimportant difference between this reaction and theforward reaction is that the latter is a rapid, irrevers-ible exothermic reaction converting H2 and Q2 towater, while the former is a reversible reaction whereH2O and O2 landing on the surface decompose toOH and H and react again to form H2O and O2 thatdesorb from the surface. The experimental data isvery well reproduced by the kinetic model calcula-tions. Also the apparent desorption energy has beenmeasured for this system and reproduced by thekinetic model.

Measurements of the oxidation of hydrogen onRh and Pd catalysts have shown that Pd behaves asPt while the measurements on Rh show a morecomplicated behaviour with a strong variation of the"apparent desorption energy" of OH with gas-mix-ture. We have by AES analysis found that this maybe due to a difference in surface impurities of boronwhen the catalyst is run in oxygen and hydrogen richgas-mixtures, respectively.

B2. Imaging of radicals desorbed in catalyticreactions

In practical catalytic processes like carexhaust clean-in"orcavalytic combustions, the reactions take placeat relatively high pressure causing an interactionbetween surface and gas phase reactions. Radicalscreated at a catalyst may initiate gas phase reactionsclose to the catalyst surface and they may be con-sumed when they react with reactants or products.This might be of great importance when choosingthe wall materials in an engine or when constructingcatalytic burners in combustion. We have in thisproject measured the concentration of OH radicals atdifferent distances outside the catalyst using a diodearray (51) and a two-dimensional CCD camera (55). We have found that the OH concentration decreaseswith increasing distance from the surface, but theexplicit behaviour is strongly dependent on pressure,pumping speed and mass flow in a complex manner.

The experiment indicate that the detected OH radi-cals are formed at the surface and subsequentlydesorb and that they are not formed in gas phasereactions outside the catalyst

B3. Studies of murtfphoton prorsssesIt is in studies of catalytic reactions of interest todevelop new measurement techniques. For this pur-pose we have built a smaller vacuum chamber inwhich we utilize resonantly enhanced multi photonionization (REMPI), where the molecules are ion-ized by a multi photon process and then detected asa ciirrent between two electrodes. The chamber isconstructed making a simultaneous comparison be-tween REMPI and LIF possible. We have here donea comparison of measurements of the rotationaltemperature of NO using the LIF and REMPI techniques (18). REMPI and LIF will laceron be used inparallel in the UHV system (56).

C: Laser lonbation Mass Spectrometry

A laser ionization time of flight, TOF, mass-spectrometer for studies of bulk samples, surfaces,gases and volatile liquids (60,61) has been built, Fig.2. The analysis of solid samples is based on sputter-ing with Ar ions, photoionization of the desorbedneutral species followed by time-of-flight mass sepa-ration and detection. The advantages of the methodare surface specificity, high sensitivity andmultielement capability or high selectivity. By sput-tering most atoms are desorbed from the outermostatom layer. Laserionization of the desorbed neutralspecies ensures a high sensitivity (ppm-range orbetter). If the ionization is performed as resonantmultiphoton ionization a specific element or com-pound can be studied with extreme selectivity andsensitivity, while non-resonant ionization combinedwith TOF-measurements provides a multielementspectrum revealing the total sample composition.The set-up has been used for analysis of GalnAssamples (62), different steel samples (63), gases andvolatile liquids (64) and catalysts. For the analysis ofthe steel samples instrumental sensitivity factors forvarious elements have been determined from meas-urements on certified reference samples. The con-centrations of the most abundant elements in othersamples are then determined using these sensitivityfactors.


MOLECULAR PHYSICS

trig and dtliy Figure 2. Schematic of theexperimental set-up. Legend:1-Primary ion gun. 2-Gasinlet. 3-Solid sample. 4 -Excimer laser. 5-Dye laser(only by resonant MPI experi-ments. 6-Excimer or dye laserbeam, approaching a prismand a photodiode. 7-Focusinglens. &-€xtraction and accel-eration ion optics. 9-Electro-static lens. 10-Beam ofionized species. 11-Reflector.12-Detector. 13-Preamplifier.14-Digital storage oscillo-scope or boxcar integrator.TP-Turbo-molecular pumps.

prism

D: Experimental Studies of ClustersClusters with a countable number of atoms consti-tute the smallest pieces of solid matter, and as suchthey are important model systems for understandingthe embryonic growth of solid materials. The devel-opment of new techniques for producing clusters, e.g. the laser vaporization source, has made it possibleto do experiments on free clusters of basically allsolid elements and many compounds, and this hasduring the last decade established cluster science asa research area of its own. We have during the lasttwo years constructed a new experimental set-upwhere clusters can be produced of all solid elementsand reacted in a low pressure cell, separated from theproduction region.

01. Production and studies of free metaldusten with laser based methods

The set up for production and studies of metalclusters produced by laser vaporization is shown infig. 3. The system consists of two vacuum chambers,one in which the clusters are produced in a laservaporization source and seeded in a supersonic Hebeam. The cluster beam enters the second chamberthrough a 1 mm diameter skimmer and are ionizedwith pulsed laserlight, ArF 6.4 eV, and detected in alinear time-of-flightmass spectrometer. The reactiv-ity of the clusters is probed by measuring the adsorp-tion/adhesion of different gases when the clusterbeam passes through a reaction cell, containing e.g.

O2 or D2. In the mass spectrometer both reactionproducts and unreacted clusters will be detected.

Parts of a mass spectrum showing C026 reactingwith O2 at successively higher pressures are dis-played in fig. 4. Analysis of these types of spectra(69,70) has given values of the reactvity or stickingprobabilities for clusters of Fex, CON and CUN, withN =10-60.

Dual micro channel platedetector

Ion Optics

Reactant gas

Turbo-pump

Figure 3. The experiment set-up, with the clustersource, the reaction cell and the time-of-flightmass spectrometer.

132 THE CENTRE FOR

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D2. Production and studies of pure and dopedfullerenes

The development of the electric arc evaporationmethod by Krätschmer et al [W. Krätschmer, L.D.Lamb, K. Fostiropoulos and D.R. Huffman, Nature347 (1990) 354 - 358] for macroscopic production ofthe football-like carbon cluster Qo also referred to as"Buckminsterfullerene" and other fullerenes hasduring the last two years created a boom of experi-mental and theoretical research. (See project A2).Fig. 5 shows a schematic overview of the electric arcgraphite evaporator (71). When the graphite rods arebrought into contact, an electric arc is ignited be-tween them using a commercial welding supply. Thechamber is filled with approximately 100 mbar He,supplying the necessary cooling, allowing the graphiteevaporated in the arc to condense into large carbonmolecules. The soot that collects on the walls of thechamber contains a large number of stable carbonclusters. The dominant species are Qo and C70, butalso larger clusters, up to several hundred atoms arefound in mass analysis of the soot. By washing thesoot in benzene or toluene only the fullerenes aredissolved and from this fullerene solution can get apure sample by using liquid chromatography. Char-acterization of the soot or the fractions obtained inliquid chromatography have been performed usingour cluster beam machine by soft laser desorption ofthe solid samples into the molecular beam,photoionization with laser light and massspectrometric detection.

Graphite rod translation

Y//////////////////////////////////A

Figure 4. A sequence of partial mass spectra,centred around C026 • C027. The top panel showsa mass spectrum recorded with no raective gasEach of the following spectra are then recorded atsuccesively higher pressure. Figure 5. Electric arc graphite evaporator


MOLECULAR PHYSICS

C60C70 130 mbar He

260 mbar Ar

,C70

h^>^v^l4A»W*WW^^J^^VI»^^V^^^

Figure 6. Mass spectra of soot from graphite arcevaporation in different gase

E. Calculations for atomic systems

We have for a long time been engaged in theoreticalcalculations for free atoms and ions in connectionwith experimental works performed by other groupsat CTH/GU or groups abroad. Most of the work hasbeen performed on the analysis of hyperfine struc-ture (hfs), and isotope shifts (IS). The hfs of transi-tion elements has been analyzed using the effectiveoperator formalism and the results obtained arecompared with parameters evaluated with non-rela-tivistic and particularly relativistic self-consistent-field SCF methods as Hartree-Fock-Slater, (HFS),Hartree-Slater, (HS), and Hartree-Fock, (HF). (72)Usually the breakdown of LS-coupling has beenobtained by the analysis of the experimental atomicfine structure. (Theprocedureforanalysisofhyperfinestructure was presented in a review article fifteenyears ago (I. Lindgren and A. Rosén, "Case Studiesin Atomic Physics", 4, 93 (1974)). These type ofinvestigations have been extended tomulticonfiguration Dirac-Fockcalculations (MCDF)in which the breakdown of LS coupling is includedto some extent in the wavefunctions. Extensivecalculations have been done for the alkaline-earthelements to particularly analyze the breakdown ofLS-coupling, volume isotope shift and hyperfinestructure (73).

F: Related projects

EL Application of DOAS for studies ofcombustion gases

One of our students Johan Mellqvist is working parttime at FVL with Differential Optical AbsorptionSpectroscopy, DOAS. An experimental set-up hasbeen designed for measurements of differential ab-sorption cross-sections of gases such as NO, NO2and SO2 at temperatures between 20 and 400<>C (74-76). The measurements show that the differentialabsorption cross-sections are strongly temperaturedependent which has to be taken into account whenthe DOAS technique is used for measurements offlue gases as recently performed in the CFB-com-bustion unit at CTH (77).

F2. Infrared laser Stark shift spectroscopy inammonia

The Stark effect in ammonia has been analyzedtheoretically (78,79) in cooperation with SvanteHöjer at the Dept of Optoelectronics, as a comple-ment to his measurements of the absorption spectraof ammonia around 1050 cm-' using lead salt tun-able diode and CO2 lasers. The electric field depend-ent energy levels have have been evaluated bydiagonalization of a 6 x 6 energy matrix constructedusing both electric field independent and field de-pendent terms in the molecular Hamiltonian. Resultsobtained from this project can be used for measure-ments of electric fields in transformers.

F3. Applications of lasers in medicine,dermatology

In a diploma work two students Cathrina Hägertzand Magnus Levinsson, (80) have investigated thereflection and transmission of skin form pigs in the300 - 800 nm wavelength region using differentskin- and solar lotions. This project is performed incooperation with Prof Magne Alpsten Dept of Ra-diation Physics GU and Doc Olle Larkö Dept ofDermatology Sahlgrenska Hospital GU

134 THE CENTRE FOR

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Publications

Ph.D. DissertationsSten Ljungström, "Laser diagnostics and kinetics of OH

formation in the catalyzed H2 + O2 reaction", PhDThesis, GU, June 1988, ISBSN 91-7032-352-6

Tomas Wahnström, "A laser induced fluorescence study ofthe OH radical desorption in the H2 + O2 reaction onPt", PhD. Thesis, CTH, December 1989,1SBSN 91-7032459-X

Bo Wästberg, "Calculations of electronic properties ofmetal clusters, fullerenes and molecules adsorbed onsurfaces", PhD Thesis January 1992, ISBSN 91-7032-639-8

licentiate DissertationsHenrik Fallgren, "A laser ionization mass spectrometer for

the analysis of sputtered neutral species". Fil lic Thesis,GU, Feb. 1989.

Erik Fridell, "OH desorption from Pt in the catalyticformation and decomposition of water". Fil Lic Thesis,GU, June 1990.

Mats Andersson, "Laser ionization mass spcciromciry as amethod for chemical analysis of solids and surfaces",Tekn Lie Thesis CTH June 1992.

Diploma WorkMats Andersson, "Experimental and theoretical studies of

sputtering processes in connection with laser ionizationmass spectrometry", CTH June 1988.

Alf-Pctcr Elg, "Construction of a heat-pipe for generationof IR radiation using Raman processes", GU Sept1989.

Johan Mellqvist, "The Reliability of the DOAS Techniquefor Measurements on Gases at High Temperatures",CTH Sept 1990.

Cathrina Hagcrtz and Magnus Levinsson, "Reflektion ochtransmssion i hud vid bestrålning i våglängdsområdct300-800 nm",CTHSept 1991.

Fredrik Gudmundson, "Generation of VUV Light in RareGases by Frequency Tripling: Construction of Appara-tus and Theoretical Survey", CTH, May 92.

Smaller project worksL.-O Carlsson, J. Hagberg, G. Barrvik, F. Nikolajeff, N.

Wendelöw och M. Wiik, "Masspektromctrisk analysav gaser och vätskor", CTH April 1990

P. Andersson, T. Andersson, B Hägglund, T. Larsson, F.Nilarp, P. Swaren, S. Svensson, "Katalytiska reaktioneroch katalysatorytor", CTH April 1992.

Martin Jägersand, "Identification of peaks in spectra withoptimization based methods", CTH June 1991.

Reports and articles1. B Wästberg Fully numerical solutions of the molecular

Schrodinger equation: The MSXa method for nonmuffin-lin potentials. Submitted

2. B.Wästberg, Calculations of electronic properties ofmetal clusters, fullcrenes and molecules adsorbed onsurfaces. PhD Thesis January 1992, ISBSN 91-7032-639-8

3. D. Hcincmann, A. Rosén and B. Fricke, "Spin-polarized Hartree-Fock-Slaicr calculations in atomsand diatomic molecules with the finite elementmethod", Chcm. Phys. Lett.166,627 (1990).

4. D. Hcincmann, A. Rosén and B. Fricke, "Solution ofthe Hartree-Fock equations for atoms and diatomicmolecules with the finite element method", PhysicaScripta, 42,692(1990).

5. D. Heincmann and A. Rosén, Basis-independentpotential energy curves for the neutral diatomics of Li,Na and K evaluated by means of Hartree-Fock anddifferent density functional potentials, ThcorcticaChimica Acta, In press

6. J. Meyer, W.-D. Sepp, B. Fricke and A. Rosén,Computation of relalivistic symmetry orbitals for finitedouble groups, Computer Physics Communications 51.55 (1989).

7. V. Pershina, W.-D Sepp, B. Fricke and A. Rosén,Relativisuc effects in physics and chemistry of element105.1. Periodicities in properties of group 5 elements.Electronic structure of the pcntachloridcs. J. Chem.Phys. 96,8367(1992).

8. A. Rosén and T. T. Rantala, Analysis of the reactivityof small cobalt clusters, Z. Physik Pi . 205 (1986).

9. T. Wahnström, A. Rosén and T.T.Ranlala, Analysisof (he electronic properties of small niobium clusters,"Physics and Chemistry of Small Clusters", p 511,Plenum Publ. Corp. 1987. Eds. P. Jena, B. K. Rao andS. N. Khanna.


MOLEfjLAR PHYSICS

10. T. Wahnström and A. Rosén, Ab intio calculations ofthe electronic structure and effective magnetic momentof Nb4, Surf. Sci. 189/190.788 (1987).

11. B. Wästberg, A. Rosén and D. E. Ellis, First principlescalculations of the K-edgc X-ray absorption near edgespectra of some transition metal dimcrs, Proceedings ofthe ISSPIC 4 Conference, Z. Phys. PJ2,377 (1989).

12. B Wästberg, A Rosén and D E Ellis, First principlescalculations of the K-edgc X-ray absorption spectra forsome small iron and nickel clusters, Z. Phys. D13.153(1989).

13. B. Wästberg and A. Rosén, Calculations ofphotoionization cross sections for Na2-g and K2-8clusters, Z. Phys. D18,267(1991).

14. B. Wästberg and A. Rosén, Calculation ofphotoionization cross sections of small metal clusters,Proceedings of the Sth International Symposium onSmall Particles and Inorganic Clusters, ISSPIC-5,Konstanz Sept 10-14,1990, Eds. E. Recknagel and 0.EchtZ.Phys.D19,71(1991).

15. B. Wästberg and A. Rosén, Calculation of thephotoionization cross sections for small metal clusters.Springer Series in Nuclear and Particle Physics, Proc."Cluster Phenomena in Atoms and Nuclei", TurkuFinland, June 3-7,1991, Eds. M. Brenner, T. Lönnroth,F.B. Malik. Springer -Verlag Berlin Heidelberg, 1992.

16. S. Larsson, A. Volosov and A. Rosén, Optical spec-trum of the icosahcdral Qo, — follene — 60, Chcm.Phys. Lett. J3J, 501 (1987).

17. M. Braga, A. Rosén and S. Larsson, Electronictransitions in C«) and its ions, Proceedings of the SthInternational Symposium on Small Particles andInorganic Clusters, ISSPIC-5, Konstan/ Sept 10-14,1990, Eds. E. Recknagel and O. Echl, Z. Phys.D19,435(1991).

18. M. Braga, S. Larsson, A. Rosén and A. Volosov,Electron : transitions in Qo- On the origin of stronginterstellar absorption at 217 nm. Astron. Astrophys.245,232(1991).

19. A. Rosén and B. Wästberg, First principles calculationsof the ionization potentials and electron affinities of thespheroidal molecules Q» and LaQo. J. of Am. Chcm.Soc.ilfl, 8701 (1988).

20. A. Rosén and B. Wästberg, Calculations of the ioniza-tion thresholds and electron affinities of the neutral andnegatively charged C60, —follcne— 60, J. Chcm.Phys. 20,2525(1989).

2"i. A. Rosén and B. Wästberg, Elec'ronic structure ofspheroidal metal containing carbon shells: study of theLaCg) and C«> and their ions within the local densityapproximation. Proceedings of the ISSPIC 4 Confer-ence, Z. Phys. QiZ, 387 (1989).

22. B. Wästberg and A. Rosén, Electronic Structure of Ceoand its Alkali Atom Containing Compounds MC«)>M=Li, Na, K, Rb, Cs and K2C«), PhysicaScripta.44,276(1991).

23. A. Rosén and B. Wästberg, Buckminsterfullerene Qo -a surface with curvature and interesting properties,ECOSS Conference Stockholm Sept 10-14,1991,Surface Science 269/270,1121(1992).

24. A. Rosén, and D. östling, Electronic structure of dopedBuckminsterfullercnc, Mater. Res. Soc. Symp. Proc.270,141(1992).

25. A. Rosén, Analysis of the electronic structure of C«>doped with p-clcments, Z. Physik D in press

26. D. Östling, and A. Rosén, calculations of the electronicstructure of doped Buckminstcrfullerene, Proc. ISSPICVI, Chicago, Sept. 15-22,1992, Z. Physik D

27. D. östling, and A. Rosén, Electronic Properties of theC«) molecule doped with Potassium, Chem. Phys. Lett,in press

28. B. Wästberg and A. Rosén, Analysis of the position onthe 2p*-derived states for CO adsorbed on the Pl(l 10)surface. Surf. Sci. ]31, L7-L16 (1988).

29. T.T. Rantala and A. Rosén, Electronic damping ofadsorbatc motion: CO vibration on Cu (100) surface.Phys. Pev.fiH, 837 (1986)

30. J. Reif, H. B. Nielsen, O. Semler, E. Matthias, E.Westin and A. Rosén, Multiphoton processes at the(111) surface of BaF2 crystals.Physics Scripta, 2i , 532(1987).

31. E. Matthias, H. B. Nielsen, J. Reif, A. Rosén and E.Westin, Multiphoton-induccd desorption of positiveions from bariumfluoridc. Extended paper presented atthe 2nd Topical Meeting on Microphysics of SurfacesBeams and Adsorbates. Santa Fe, New Mexico, 16-18Feb. 1987. J. of Vacuum Science and Technology, fi5_,1415 (1987).

32. H.B. Nielsen, J. Reif, E. Matthias, E. Westin and A.Rosén, Multiphoton- Induced Desorption from BaF2(111) in Desorption Induced by Electronic Transitions,DIET III, Proceedings of the Third InternationalWorkshop of Desorption Induced Electron Transitions,Springer Scries in Surface Science.

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33. A. Rosén, E. Wcsiin, E. Matthias, H. B. Nielsen and J.Reif, Molecular cluster calculations for the Analysis ofLaser Induced Emission of Electrons and Ions from the(111) Surface of BaF2. Invited paper to the EPS 7Conference 'Trends in Physics", Helsinki, Aug. 1987,Proceeding, Physics Scripta 122,184 (1988).

34. E. Westin, A. Rosén and E. Matthias, Molecular clustercalculations of the electronic structure of the (111)surface of CaF* Fourth International Workshop onDesorption Induced by Electronic Transitions DIETIV, Gloggnitz, Austria, OcL 2-4,1989. SpringerSeries in Surface Sciences 19,316(1990).

35. E Westin, Evaluation of electrostatic potentials forsurfaces and solids from an embedding scheme. Inmanuscript

36. J. Reif, P. Tepper, E. Matthias, E. Westin and A.Rosén, Use of optical second harmonic generation forsurface crystallographic studies on cubic ionic crystals.Applied, Physics, B4fc 131 (1988).

37. E. Westin and A. Rosén, Study of the electronicstructure and second order nonlinear opticalpolarizabilitics at surfaces of ionic crystals, ECOSSConference Stockhom, Sept 10-14,1991. SurfaceScience, 269/270,577(1992).

38. E. Westin and A. Rosén, Study of linear and nonlinearmicroscopic polarizabilitites of Cgo, Mater. Res. Soc.Symp. Proc. 270,221(1992).

39. E. Westin and A. Rosén, Evaluation of linear andnonlinear microscopic polarizabilities of Ceo, Int. J.Mod. Phys. B) Proc. of Adriatico Conference onClusters and Fullerencs, ICTP Italy 23-26 June 1992.Eds. V. Kumar, T. P. Martin & E Tosatti.

40. E. Westin and A. Rosén, Analysis of absorptionspectrum of Ceo and its doped compounds. Proc.ISSPIC VI, Chicago, Sept. 15-22,1992, Z. Physik D

41. E. Westin and A. Rosén, Evaluation of nonlinearmicroscopic polarizabilitites of Ceo and its DopedCompounds, Proc. ISSPIC VI, Chicago, Sept. 15-22,1992, Z. Physik D

42. D. Östling, P. Apell and A. Rosén, Theory of Collec-tive Resonances of the Ceo Molecule, Euro. Phys. Lett.In press

43. D. Östling, P. Apell and A. Rosén, Analysis of collec-tive resonances and electromagnetic properties of theC6o molecule, Proc. ISSPIC VI, Chicago, Sept. 15-22,1992, Z. Physik D

44. A. Rosén, Kolfotbollar - Fullerener - ett nytt materialav kol. Fysikaktuellt, Fysikaktuellt Nr 3-4, September1991

45. S. Ljungström, B. Kascmo, A. Rosén, T. Wahnströmand E.Fridell, An Experimental Study of the Kineticsof OH and H2O Formation on Pt in the H2 + O2Reaction, Surface Science 216,63 (1989).

46. T. Wahnström, A Laser Induced Fluorescence Study ofOH Radical Desorption in the H2 + O2 reaction on Pi.PhD Thesis, Göteborg Nov 1989.

47. T. Wahnström, E. Fridell, S. Ljungström, B Hellsing,B. Kascmo and A. Rosén, Determination of theactivation energy for OH desorption in the H2 + O2

reaction on polycrystalline platinum.. Surface Science,223, L905 (1989).

48. T. Wahnström, S. Ljungström, A. Rosén and B.Kasemo, Laser-induced fluorescence studies of therotational state populations of OH desorbed in theoxidation of hydrogen on Pt, Surface Science, 234,439(1990).

49. E. Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A.Rosén and T. Wahnström, Determination of theactivation energy for OH desorption in the catalytic H2

+ O2 reaction on Pt. Extended abstract. Proceeding ofthe 1 lth international Vacuum Congress (IVC-11) and7th International Conference on Solid Surfaces (ICSS-7) 25-29 Sept. 1989. Eds. A. Benninghoven and H. P.Bonzel, Vacuum, 41,732 (1990).

50. E. Fridell, OH dcsorplion from Pt in the catalyticformation and decomposition of water, Lie Thesis, GU,June 1990.

51. E. Fridell, U. Westblom, M. Aldén and A. Rosén,Spatially resolved laser- induced fluorescence imagingof OH produced in the oxidation of hydrogen onplatinum, J. of Catalysis, 128,92 (1991).

52. E. Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A.Rosén and T. Wahnström, Hydroxyl desorption fromplatinum in the catalytic formation and decompositionof water, J. Vac. Sci. Tcchnol. A9,2322 (1991).

53. E. Fridell, Kinetics of OH formation on Pi in H2O/O2mixtures at high temperatures, Chcm. Phys. Lett. 188,487 (1992).

54. E. Fridell, M. Andersson, Alf-Peter Elg, S Ljungström,B. Kasemo and A. Rosén, Studies of intermediates incatalytic reactions, catalysts, and catalytic combustionusing laser spectroscopy, mass spectrometry andkinetic modelling, FÖRPEX, 4-5 Nov 1992.

55. F. Gudmundsson, E. Fridell, and A. Rosén, SpatiallyResolved Laser-Induced Fluorescence Imaging of OHProduced in Catalytic Reactions, FÖRPEX, 4-5 Nov1992.


MOLECULAR PHYSICS

56. A. P. Elg, S Ljungström, and A. Rosén, A comparisonof the use of the REMPI and LIF techniques for studiesof molecules in catalytic reactions, FÖRPEX, 4-5 Nov1992.

57. E. Fridell, B. Kasemo and A. Rosén, A laser inducedfluorescence study of OH desorption from Pt in H2O +Hj and H2O + H2 mixtures. Langmuir, submitted

58. M. Andersson, J. Persson and A. Rosén, Experimentalstudies of the electronic structure and catalytic proper-ties of metal clusters, FÖRPEX, 4-5 Nov 1992.

59. A. P. Elg, S Ljungström, and A. Rosén, A comparisonof the use of the REMPI and LIF techniques for studiesof molecules in catalytic reactions, FÖRPEX, 4-5 Nov1992.

60. H. Fallgren, A laser ionization mass spectrometer forthe analysis of sputtered neutral species, Fil lic Thesis,GU, Feb. 1989.

61. M. Andersson, Experimentella och teoretiska studier avsputtringsproecser i samband med lascrjonisations-masspektrometri. Examensarbete, June 1988.

62. M. Andersson, H. Fallgren and A. Rosén A time offlight mass spectrometer for the analysis of solids,gases and liquids, Proceeding of the Fifth InternationalSymposium on Resonance Ionization Spcctroscopyand its Applications (RIS-90) Varese Italy, 16-21September 1990, Eds. J.E.Parks and N. Omcnetto, Inst.Phys. Conf. Scr. No 114:459 (1991).

63. M. Andersson and A. Rosén, Quantitative Analysis ofSteel Samples with Laser lonization Mass Spcctro-metry. "XXVII Colloquim SpectroscopiumInternationale", June 10-14,1991, Bergen Norway J.Anal. At. Spcctr. 7,261(1992).

64. L.-O Carlsson, J. Hagberg, G. Barrvik, F. Nikolajcff,N. Wendelöw och M. Wiik, Masspektrometrisk analysav gaser och vätskor, Projektarbete CTH, April 1990

65. P. Andersson, T. Andersson, B Hägglund, T. Larsson,F. Nilarp, P. Swarcn, S. Svensson, Projektarbete April1992.

66. F. Gudmundson, Generation of VUV Light in RareGases by Frequency Tripling: Construction of Appara-tus and Theoretical Survey, Diploma work CTH, May92.

67. H. Fallgrcn and T.P. Martin, Photoabsorplion of Csgand CsioO clusters, Chcm. Phys. Lett. 168,233(1990).

68. H. Fallgren K. M. Brown, and T.P. Martin, Photo-absorption spectra of CSJVO and Csv clusters, Proceed-ings of the 5th International Symposium on Small

Particles and Inorganic Clusters, ISSPIC-5, Konstanz,Sept 10-14,1990, Eds. E. Recknagel and O. Echt Z.Phys. D19,81, (1991).

69. }L. Persson, M. Andersson and A. Rosén, Reactivityof small transition metal clusters, Proc. ISSPIC VI,Chicago, Sept. 15-22,1992, Z. Physik D

70. M. Andersson, J. L. Persson and A. Rosén, Oxidationof small transition metal clusters,, Cancun, Sept. 21-2x, 1992, Nanostructured Materials

71. A. Rosén, M. Andersson, F. Gudmundson, J. Persson,E. Wcstin, B. Wästberg, D. Östling, FuIIcrcnes - newmaterials made from soot, FÖRPEX, 4-5 Nov 1992.

72. T. Olsson, L. Fraenkel, I. Lindgren, A. Nyberg, L.Robcrtsson and A. Rosén, Laser and radiofrcquencyspectroscopy of the 4d55s 5D0> 1,2,3,4 and 4d45s5p5P],2,3 states in Mo I: Hypcrfine structure and isotopeshifts'. Physica Scripta M, 24 (1986).

73. T. Olsson, A. Rosén, B. Frickc and G. Torbohm,Analysis of the electronic structure, hyperfinc structure,and volume isotope shifts in the low lying states of Ba Iand Ba II. Physica Scripta 22,730(1988)

74. J. Mellqvist, The Reliability of the DOAS Techniquefor Measurements on Gases at High Temperatures,Diploma work

75. H. Axelsson, J. Mcllqvist and V. Vcscly, Utvärderingav temperatur- och olincaritctscffckicrs inverkan påDOAS- teknikens tillförlitlighet vid rökgasanalys, 1VL,Värmcforsk rapport Nr 409.

76. J. Mcllqvist, H. Axelsson and A. Rosén, The tempera-ture dependence of the absorption spectra of NO, NO2and SO2 in the DOAS application "XXVII ColloquimSpectroscopium Internationale", June 10-14,1991,Bergen Norway, Analyst, 117,417 (1992).

77. J. Mcllqvist, H. Axelsson and A. Rosén, The DOAStechnique in emission monitoring of flue gases,F?RPEX,4-5 Nov 1992.

78. S. Höjer, H. Ahlbcrg and A. Rosén, Inlrarcd LaserStark Shift Spcctroscopy in Ammonia: Theoretical andExperimental analysis for Sensing Electric FieldStrength, Appl. Phys. B52,200 (1991)

79. S. Höjer, H. Ahlbcrg and A. Rosén, Measurements ofthe electric field strength dependent line strength of thessR(5,3) ammonia line, Report No 90252, Departmentof Optoelectronics and Electrical Measurements, CTH1990.

80. Cathrina Hägcrlz and Magnus Levinsson, "Reflektionoch transmssion i hud vid bestrålning i våglängds-området 300-800 nm", CTH Scpt 1991.

138 THE CENTRE FOR

Engineering Chemistry

Research SummaryThe research activities within the materials sciencearea at the department of Engineering Chemistry isconcentrated on the preparation and characterizationof different materials in the form of small particles,what we call small particle technology. We considerthe small particle technology an approch to achievedifferent objectives. One such objective is new andimproved catalysts. Catalysts are invariably built upof different types of small particles. Properties ofthese particles such as size, shape, chemical compo-sition etc determine the pore-size, surface area andactivity of the catalysts. A detailed knowledge ofpreparation and characterization of systems of smallparticles is therefore essential if one wants todevelopimproved catalysts. Most of ourresearch in the smallparticle technology area is currently directed to-wards development of catalysts, especially catalystsfor pollution control. Knowledge of small particlesis, however, also essential in other areas such asadsorbents, ceramics, inorganic membranes, pig-ments, fillers in paper and plastics etc. Furthermore,development of new materials in the form of smallparticles can be considered an objective in itself asexemplified by our research activities on zeolitesynthesis.

AddressDepartment of Engineering ChemistryChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31772 2970Fax+46 31 160062

StaffSenior MembersSven-Ingvar Andersson tekn. dr.Börje Gevert tekn. dr.Lars Löwendahl tekn. drJan-Erik Otterstedt professorJohan Sterte docent

Graduate StudentsBrian Schoeman civ.ing.Magnus Skoglundh tekn.lic.Anders Tömcrona civ.ing

Technical StaffTorild Isaksson ing.Kurt Löfgren ing.Mary Mattsson ing.

Secretary:Elisabeth Hamawi

Major InstrumentationReactors• FCC-Pilot plant. Feedstock, prepared either by

in-house process studies or submitted fromexternal sources, are evaluated for crackingcharacteristics (product yields and qualities) ina continous circulating fluid catalytic crackingunit built under license from the AtlanticRichfield Company. Having four interchange-able reactors, this unit can handle feedstockswith Conradson Carbon Numbers up to 4 andduplicate the performance of full scale com-mercial FCC units.

• Microactivity (MAT) test unit for crackingcatalysts. Built to meet ASTM standardD3907-80, this unit has been modified toimprove accuracy by careful control of bothtemperature and the feed injection systems.MAT units are world-wide analytic standard ofthe petroleum and catalyst industries.

• Continous hydroprocessing reactors for cata-lytic treatment and conversion of oils. Twounits for 30-150 ml of catalyst, pressures ofmaximum 160 bar, and temperatures of 500°C.One atmospheric unit for temperatures up to450°C. Both different oils, model compounds,and catalysts can be studied.


ENGINEERING CHEMISTRY

• Batch reactor for hydroprocessing studies.Capable of operating at pressures up to 200 barand temperatures up to 350°C, this unit is usefulin studying reaction kinetics and mechanismsin regard to both feedstocks and catalysts.

• Pulse reactor. A microreactor on-line with agas chromatograph for rapid screening ofcatalyst activity. This reactor is also useful forchemisorption studies.

• Reactor system for activity testing of automo-tive catalysts and catalysts for combustion ofsolvent vapors with on-line analysis of oxygen(OM14, Beckman), carbon monoxide(UNOR6, Maihak), carbon dioxide (UNOR6,Maihak), nitrogen oxides (CLD5O2, TECAN)and total hydrocarbons (VE5, JUM ENG.)

Analytical facilities• Digisorb 2600 from Micromeriucs. An auto-

mated instrument for measuring the surfacearea, pore volume and pore size distribution(range 14-3000 Å) of porous solids.

• Chemisorb 2800 from Micromeritics. Thisautomatic instrument measures chemisorptionof such gases as hydrogen, CO, NO on metaland metal oxide catalysts. Chemisorption datacan be correlated to catalyst activity. It oper-ates in the ranges 25-750°C and 10-5 to 900mm Hg pressure.

• Scanning electron microscope equipped withx-ray microanalysis including a mappingfunction (Link QX 200) to study elementalcomposition (Jeol, JSM-5200).

• Elemental analyzers: LECO RO-116, LECOSC-132, LECO CHN-600. The CHN-600measures carbon, hydrogen, and nitrogen. TheSC-132 measures sulfur content of oil, coal,coke, and other non-metallic materials, whilethe RO-116 measures oxygen content.

• Two Hewlett Packard gas chromatographs.Two Series 5880A including HP 3888AIntegrators and HP 7671A automatic samplersused for analysis of feedstocks and the liquidand gaseous products from laboratory runs.

• Liquid chromatographs. Two flexible systems(Hitachi and Waters) for HPLC and GPC, fordetalied analysis of hydrocarbons, lignins, andother organic compounds.

• Thermal Activity Monitor 2270 from Therme-tric. This fully automated instrument measuresheat evolution in the range 0.1-3000pW,approximately equivalent to differences intemperature of 10-8 - 1(H K.

• Malvem Zetasizer 2c. Laser scattering instru-ment for measurement of Z-potential, electro-phoretic mobility, particle size, and diffusioncoefficient.

• In addition to these advanced instruments wehave a number of gas-chromatographs, anatomic absorption spectrophotometer (PerkinElmer), a UV-spectrophotometer (Shimadzu)and instruments for measurement of viscosity,surface tension etc.

Materials preparation facilities• Vacuum distillation unit for petroleum fractio-

nation. Capable of working at very low pres-sures (down to 0.2 Pa) to produce petroleumcuts with high TBP.

• Ultrafiltration unit with tangential flow forrapid concentration of e.g. colloidal particlesfor batch size up to 100 litres (Millipore,Pellicon Cassette System.)

• Ultracentrifuge. Sorvall RC5-b. Maximumrelative centrifuge force 49 000 g.

• Tank reactor system. Computer controlledreactor system for large scale preparations ofsols and zeolites.

• Zeolite preparation equipment. Autoclaves andreactors are available for preparation of typesA, X, Y, rare earth Y, calcined REY, ultra-stable Y, ZSM-5, silicalite, and mordenite inquantites up to 5 kg.

• Spray dryer. Niro Mobil Minor spray dyersequipped with a counter/cocurrent two fluidnozzle for drying of aqueous slurries.

• Extruder of radial type (Nica) for low andmedium pressure preparation of 0.2-5 kgsamples.

140 THE CENTRE FOR


Steam and/or heat-treaters. Two units fordeactivation of catalysts with a combination ofsteam and air. One unit can handle catalystsamples of 10-100 g and the other unit samplesof 2-4 kg at temperatures up to 800°C.

Pulping and bleaching equipment. Autoclavesfor pulping and bleaching of pulp. Equipmentfor gas treatment of wood pulp.

In addition to this we have a multi-purposeunit, a freeze-drying unit, a ball-mill, screeningequipment, ovens, vacuum ovens, furnacesetc.

Major Fields of ResearchA: New catalysts and materials for pollution

controlparticipants: Jan-Erik Otterstedt, Johan Sterte,Lars Löwendahl, Magnus Skoglundh, AndersTörncrona

B: Refining catalysts.participants: Jan-Erik Otterstedt, Johan Sterte,Börje Gevert, Ying Zhong-Shu

C: Synthesis of zeolites and pillared clays,participants: Jan-Erik Otterstedt, Johan Sterte,Brian Schoeman, Anna-Karin Johansson

Research Projects

A: New Catalysts and Materialsfor Pollution Control.

A l : Noble Metal Catalysts for Pollution ControlIn this project we have studied the effect of differentwash-coat materials in noble metal catalysts forreduction of pollutants in automotive exhaust and inindustrial waste and stockgases. The objective wasto find wash-coat materials which combine a largesurface area with a large pore size and a highavailability of the active species on the catalystsurface. Wash-coat materials such as Na-free silica,fibrillar alumina and hydrothermally treated aluminawere studied and compared with corpuscular aluminaconventionally used in catalytic converters.

Fibrillar boehmite and hydrothermally treatedalumina were found to be more effective wash-coatmaterials than corpuscular alumina as shown bylower light-off temperatures for oxidation of xylene.

We have also studied the effects of the totalcontent at Pd+Pt and the ratio of Pd to Pt on the light-off temperature for oxidation of cO and differenthydrocarbons. The optimal Pd:Pt ratio was found tobe 80:20on a molar basis. This project is financed bySTU and PERSTORP AB.References: See publication list No. 35.36

A2: Transition Metal Oxide Based Catalystsfor Pollution Control

In this project we are investigating inorganic mate-rials, primarily of perovskite or zeolite typ as caa-lysts for oxidation of hydrocarbons and for reductionof nitrogen oxides. Perovskite structures containingLa, Sr, Co, Cu have been tested with and withoutdoping with Ru. Doping with Ru results in anenhanced activity for NO reduction. Of particularinterest are La-Sr-Cu perovskites as they show asignificant NO reduction activity even in the pres-ence of relatively large amounts of oxygen.

A preliminary study of Cu-exchanged zeoliteZSM-5 as a catalyst for NO reduction gave verypromising results. A high conversion of NO in thepresence of 10% O2 was obtained. This material

may be of interest for reduction of nitric oxides indiesel exhausts. This project isfinanced by NUTEK.

A3: Fibrous Catalysts for Pollution ControlThe objective of this project is to build up amicroporous structure on quartz fibers. This materialis to be used for cleaning of diesel exhaust gases. Wehave managed to prepare such a material. The mate-rial consists of 2 pm quartz fibers coated with a



microporous structure of silica particles (see figureabove). The silica particles are applied on the fibersurface by electrostatic forces. After a hydrothermaltreatment the structure is mechanically stable andhas a high specific surface area {~Wrv2 /g). Ourintention is now to prepare a filter from this type offibers with optimal properties for filtering of sootparticles in diesel exhaust gases and then to impreg-nate the washcoat with active metals and test it asa catalyst for oxidation of soot and hydrocarbons indiesel exhaust gases. This project is financed byVolvo Research Foundation.

B: Refining CatalystsB l : New Catalysts and Processes for Upgrading

of Coal Tars to Transportation FuelsThis project has the objective to develop new cata-lysts for upgrading of coal oils to transportation forfuels primarily by hydroprocessing and catalyticcracking. The project is part of an international IEAproject on hydropyrolysisof coal. Within this projectwe have developed cracking catalysts andhydroprocessing catalysts adapted for the upgradingof coal tars. This catalyst is also very active forhydrodemetallization of heavy petroleum oil frac-tions. This project is financed by NUTEK.References: See publication list No. 28,29

C: Zeolite Synthesis

C l : Colloidal Zeolites bySmall Particle Technology

We have developed methods for the preparation ofa number of different zeolites, e.g. zeolite Y, zeoliteA, ZSM-2, hydroxysodalite and silicate, in the formof monodisperse sols of discrete microcrystals.These products are unique as they exist as stablecollodial suspensions in which the micro crystalshave a size of less than 100 nm and in some caseseven less than 50 nm. An advantage with the synthe-sis procedure is that the zeolites are crystallized fromclear solutions, in contrast to conventional zeolitesynthesis in which the zeolites are crystallized froman amorphous gel. This opens unique possibilities tostudy the zeolite crystallization mechanisms by di-rect methods, such asdynamic light scattering, whichcannot be used when the zeolite is crystallized froma gel. We are now looking at different technicalapplications for micro-crystalline zeolites. Thisproject is financed by TFR

SEM photograph of conventional zeolite Y crystals.

SEM photograph of collodial particlesof type zeolite Y.

Collodial zeolite hydroxysodaliteparticle size <40 nm.

142 THE CENTRE FOR


PublicationsPh.D. Dissertations"Dclignification and Blcachability of Kraft Pulps

Prctrcaicd with Nitrogen Dioxide". 1992-04-09, PerLarsson

"Experimental studies of aqueous surfactant systems byuse of membrane filtration". 1992-06-16, Salch MMahdi

"Oxygen-alkali treatment of kraft pulp ?nd ccllobiitol".1992-09-09, Bengt Järrchult

"Influence of the gas phase on pretrcatment of kraft pulpwith nitrogen oxides". 1992-09-11, Dennis Rasmusson

Licentiate Dissertations"Nya katalysatorer för avmctalliscring av tunga oljor".

1988, Kerstin Lindström

"Membrane filtration for the recycling of mctalworkingfluids". 1989, Salch M Mahdi

"Surface chemistry aspects on adsorption from a multi-component model mctalworking fluid". 1989, MatsTunius

"Förbehandling av sulfatmassa och sulfallignin medkväveoxider". 1990, Urban öjtcg

"Hydromctallisation of Nickel and vanadyl-ctioporphy-rincs". 1991-01-21 Peter Abrahamsson

"Nobel metal catalysts for combustion of volatile organiccompounds". 1992-03-27 Magnus Skoglundh

Diploma WorkAndersson, Pär "Hydroproccssing of directly liquefied

biomass" 1988

Sandqvist, Stefan " Hydroproccssing of directly liquefiedbiomass"

Evaldsson, Lennart" Catalytic oxidation of xylcne.Evaluation of monolith catalyst coated with AI2O3"1988

Wcttcrlin, Karin " The amount of organic material in thewaste water from AB Pripps Bryggerier and proposalfor its reduction" 1988

Rubinstein, Li" The amount of organic material in thewaste water from AB Pripps Bryggerier and proposalfor its reduction" 1988

Svensson, Stefan " Ethylcyanoacclalc. Process evaluationincluding cost estimate" 1988

Abrahamsson, Peter "Improved phosporic acid catalyst onsilica for oligomerization of iso-butcne topolygasolinc" 1988

Gränsbo, Göran" Water soluble polymers and theirrhcological properties" 1988

Nilsson, Charlotta " Anaerobic digestion of biomass andthe organic fraction of municipal solid waste" 1989

Briihl, Pia " Anaerobic digestion of biomass and theorganic fraction of municipal solid waste" 1989

Jönsson, Rutger "Studies of fillers" 1989

Schocman, Brian "Synthesis of zcolitic microcrystals"1989

Skoglundh, Magnus "Promotion effects of Pt and Pd oncatalytic oxidation of xylcne" 1989

Andersson, Cecilia "Development and preparation ofSynthetic Collector" 1989

Gren, Anette " Development and preparation of SyntheticCollector" 1989

Mrak. Jonni" A study of various ash components,CaCOys and carbons N2O-catalysing effect." 1989

Elofsson, Ulrika " Different partstrcams influence inrespect to the cleaning result in the wastcwatcr treat-ment plant at Hallsta papcrmill" 1989

Dcllvc, Anna-Carin " Catalytic Hydrogenation ofAnthraquinonc: support structure with high specificsurface area and large average pore size" 1989

Karlsson, Jan " Investigation of the influence of metalpoisoning on cracking catalysts containing differentlypesofzeolitcY"1990

Eriksson, Mikael, "Hydrodcoxygcnation of dimcthylphe-nols over sulphidcd cobolt molybdenum catalyst:activation energies" 1990

Eriksson, Peter "Hydrodcoxygcnation of dimcihylphcnolsover sulphidcd cobolt molybdenum catalyst: activationenergies" 1990

Höskuldsson, Pall" Manufacture of Zeolite A fromKaoline clay" 1990

Hcijnesson, Anette " Retention aid systems in paper" 1990

Strid, Maria " Bleaching of birch kraft pulp with nitrogendioxide without elemental chlorine" 1990



Greenwood, Peter" The blcachability with chlorinedioxide of different oxygen bleached, prctrcatcd orunprctrcatcd kraft pulps" 1991

Karlberg, Helena " The effect of catalyst pore structure onoxidation products under hydro-processing conditions"1991

Öhman, Cecilia " Fat containing waste prevention" 1991

Fajcrsson, Måns " Catalytic total oxidation of kctones andaldehydes" 1992

Nordqvist, Anna " Reduction of aromatic compounds frompolluted water with airstrippingtcchnic" 1992

Pettersson, Stina " Catalytic reduction of NO in automativeexhausts over mixed oxides of Pcrovskitc-typc" 1992

Synncrdahl, Pcr-Olof" Final bleaching of NOx-trcatcdpulp" 1992

Tcgnandcr, Anna " Rccirculation of process water in thezinkphosphating process with elcctrodialysis" 1992

Åhman, Johan "A comparative evaluation of kompopig-ment: A new type of pigment" 1992

Reports and articles1. Axelsson, I.M., Löwcndahl, L. and Olterstcdt, J-E.,

"Hydrolhcrmal Stability of Siiica as a support forPlatinum in an Oxidation Catalyst". Appl. Cat. ,44,251(1988).

2. Elvin, F., Ottcrstcdt, J-E. and Stcrtc, J., "DEMET-proccss for dcmetallization of fluid cracking catalysts".ACS Symposium series, 375,229-237 (1988).

3. Gcvcrt, S.B., Andersson, A.Järås, S.G. andSandqvist,S., "Hydroproccssing of directly liquefiedbiomass". Preprints, Am.Chcm.Soc.,FuclChcm.,33,4913-19(1988)

4. Kjällström, B., Baker, E.G., Beckman, D., Elliott, C.C.,Gevcrt,S.B., Hömcll, C, östman, A., Nissalä, M. andSoulantausta, Y., 'Technocconomic assessment ofdirect biomass liquefaction proccsscs.Fundamcntals ofthcrmochcmical biomass conversion". Phoenix, May2-6,1988

5. Mcnon, P.G., "Hydrogen as a tool for characterizationof catalyst surfaces by chemisorption, gas tilrauon andtemperature-programmed techniques". Chapter 4 inHydrogen Effects in Catalysis-Fundamentals andPractical Applications. P.G.Menon & Z.Paäl(Eds.),Marccl Dckkcr: New York, (1988)

6. Menon, P.G., "Hydrogen effects in industrial catalysis.Chapter 7 in Hydrogen Effects in Catalysis-Fundamen-tals and Practical Applications.P.G.Menon & Z.Paäl(Eds.), Marcel Dekken New York, (1988).

7. Oticrstedt, J-E., Gevcrt, S.B. and Sterte, J., "Catalyticcracking of heavy oils." ACS Symposium Scries, 375266 (1988).

8. Otterstcdt, J-E., Yan-Ming, Zhu. and Sterte, J.,"Cata-lytic Cracking of Heavy Oil over Catalysts ContainingDifferent Types of Zeolite Y in Active and InactiveMatrices Applied Catalysis, 38,143-155 (1988)

9. Stertc, J, "Hydrolhcrmal Treatment of HydroxycationPrecursor Solutions". Catalysis Today, 2,219-23» (1988)

10. Stertc,J.Jhulin, H.,Otterstcdt, J-E. and Massoth, F.E."Characterization of Alumina-MontmorilloniteComplexes". Applied Catalysis, 38,119-129 (1988)

11. Stcrtc, J. and Otterstcdt, J-E. "Catalytic Cracking ofHeavy Oil: Use of Alumina-Montmorillonites Both asCatalysts and as Matrices for Rare Earth ExchangeZeolite Y Molecular Sieve." Applied Catalysis 38,131-142(1988)

12. Evaldsson, L.Lowcndahl, L. and Ottcrstcdl, J-E,"Fibrillar Alumina as a Wash-Coat on Monoliths in theCatalytic Oxidation of Xylcnc", Appl. Cat. 55 (1989)123.

13. Golcc, K.,Hill, E.C., Kazcmi, P. and Sköld, R.O." Oil/water partition for some hydroxyalkylamincs andantimicrobial efficiency in mctalworking coolants".Tribology International, 22 (1989) 375-382

14. Ottcrstcdt, J-E-.Schocman, B. and Stcrtc, J. "Effektivazcolitcr tar bort ammoniak ifrån kloaker" KemiskTidskrift,! 3,49,(1989)

15. Ottcrstcdt, J-E.,Persson, G and Wannholt, L. 'Teknikför uLslappsprcvcntion 1: Problcminvcntcring". KemiskTidskrifl.14,1989

16. Stertc, J. "Hydrothcrmal Stability and CatalyticCracking Performance of some pillared Clays".Preprints ,Div of Petrol.Chcm. ACS,34,489(1989).

17. Elliott, D.C., Baker.E.G., Östman, A.. Gcvcrt, B.S.,Beckman, D., Solantansta.Y. and Hocmcll, C."A Technical Economic Analysis of Direct BiomassLiquefaction" Energy from Biomass and Wastes, 13,743-67(1990)

18. Elliott, D.C., Baker, E.G., Beckman, D., Solantausla,Y., Tulcnhcimo, V., Gcvcrt, S.B., Hocrncll.C, östman,A. and Kjcllström.B. "Tcchnocconomic Assessment ofDirekt Biomass Liquefaction to Transportationfucls",Biomass,22,251 -69 (1990)

144 THE CENTRE FOR


19. Gcvcrt, S.B., Andersson, B.W., Järäs, S.G., Tokarz,M.T. and Sandqvist, S.P., "Hydroprocessing of directlyliquefied biomass with large pore catalysts". Energyand Fuels.4,78 (1990)

20. Gevert, S.B., Bruehl, P., Nilsson, P., Linne, M. andNilsson, B, "Digestion of Lucem and the OrganicFraction of MSW". Energy from Biomass andWastcs,13,981-99(1990)

21. Gevert, S.B., Abrahamsson, P. and Järås, S.,"Oligomcrization of Isobutcnc with an ImprovedCatalyst". ACS Symposium Series, 437 272 (1990)

22. Löwcndahli. and Otterstedt, J-E., "Effect ofHydrothermal Treatment on Alumina as Support forNoble Metal Catalysts". Appl. Cat. 59,89 (1990)

23. Mcnon, P.G., "Coke on catalysts-Harmful, Harmless,Invisible and beneficial types. Journal of MolecularCatalysis, 59,207-220 (1990)

24. Mcnon, P.G., Lundin, J., Engwall, K. and Holmlid, L."Mechanism of potassium loss by dcsorpiion from aniron oxide catalyst for the styrene process. CatalysisUtters, 6.85-93 (1990)

25. Otterstedt, J-E., Gevcrt, S.B., Löwendahl, L. andStcrte, J., Articles on "Pollution Prevention Technol-ogy" in Kemisk Tidskrift (Kl).a)"Ytfcnomcn klarar luftföroreningar"KT1/1990,31^0b)"Fasseparcring renar vatten och luft"KT 2/1990,25-35c)"Mikroorganismer bryter ned föroreningar"KT 3/1990,73-81d)"Hur klarar vi avfallsproblcmet?" KT 4/1990,99-110c)"Rcn teknik minimcrar utsläpp och avfall"KT 5/1990,39-49

26. Stcrtc, J, "Preparation and Properties of Largc-PorcRE/Al-pillarcd Montmorillonitcs. A Comparison ofRE-cations". Preprints Vth International Symposiumon "Scientific Basis for the Preparation of HctcrogcnousCatalysts".p.l 13-122 (1990).

27. Sterte, J., "Preparation and Properties of PillaredIntcrstratificd Illitc/Montmorillonitcs". Clays and ClayMinerals, 38,(1990)609.

28. Haglund, R., Ottcrstedt, J-E., Stcrtc, J., "Upgrading ofHydropyrolysis Coal Tar by Hydroproccssing" ErdölErdgas Kohle. 107 Jahrgang, Hcft 5, Mai 1991

29. Otlerstedt, J-E., Yan-Ming, Zhu. and Stcrte. J."Effects of matrix alumina-silica Ratio on the perfor-mance of heavy oil cracking catalysts containingzeolite Y in matrices of amorphous silica-alumina".Applied Catalysis, 70, (1991) 43-52

30. Ottcrstedt, J-E., Gcvcrt, B., Stcrtc, J., Articles on"Catalytic Conversion of Petroleum" in KemiskTidskrift (KT).a) "Effektivare raff gräver djupare i oljefatet" KT 1/1991,31-38b) "Bensin går alltid att göra men det kostar" KT 2/1991,39-42.

31. Elliott, D.C., Beckman. D., Bridgcwatcr, A.V.,Dicbold, J.P., Gevert, S.B. and Solantausta, Y.,"Developments in direct thcrmochemical liquefactionof biomass: 1983-1990. Energy & Fuels, 1991,5,9.399-410.

32. Menon, P.G. and Vrieland.CE., "Nature of the cataly-tically active carbonaceous sites for the dchydrogena-tion of cthylbcnzcnc to styrcne: A brief review.Applied Catalysis.77,1-8.(1991)

33. Mcnon, P.G., Engvall, K. and Holmlid, L, "Compara-tive loss of alkali promoter by dcsorpiion from twocatalysts for the dchydrogcnalion of cihylbcnzcnc tostyrcne". Applied Catalysis, 77,235.241 (1991)

34. Mcnon, P.G., "Post mortem examination of industrialcatalysts". Catalysis Today, 11,161-172 (1991)

35. Skoglundh.M., Löwendahl. L. and Otlcrslcdt, J-E."Combination of Pt and Pd on Modified AluminaSupports as Oxidation Catalysts for Pollution Control.Applied Catalysis, 77 (1991)9.

36. Skoglundh, M., Löwendahl, L., Mcnon, P.G.,Stenbom, B.Jacobs, JP., Van Kcsscl. O. andBrongcrsma, H.H., "Characterization of a Pt-Pdcombustion catalyst on an alumina washcoat, with andwithout prior hydrothcrmal treatment of the washcoat".Catalysis Letters, 13 (1992) 27-38

37. Stcrtc, J., "Preparation and Properties of Large/PoreLa/Al-pillarcd Montmorillonitc". Clays & ClayMinerals, 39 (1991) 167.

38. Mcnon, P.G., Holmlid, L., Engvall, K. and Åman, C."A new approach to loss of alkali promoter fromindustrial catalysts: Importance of the excited stale ofthe alkali". 10th International Congress on Catalysis,Budapest, July 1992. Paper accepted for oral presenta-tion.


Electronic andopto-electronicmaterialsSolid State Electronics 148Semiconductor Physics and Heterostructures. 157Liquid Crystals 164


Solid State Electronics

Research summaryThe research at the Department of Solid State Elec-tronics is specialized on silicon and silicon relatedmaterials, devices and circuits. Within these bordersthe activities take place in a rather wide interval on anaxis representing the dimension basic-applied re-search. In recent years, our work has involved thethermodynamic properties of charge carriers in semi-conductors, materials phenomena in the bulk ofsilicon and at a variety of different interfaces, newtechnologies for device preparation, novel devicesand design of circuits in silicon technology.

We cooperate with a number of the larger Swedishcompanies (ABB, Ericsson, Volvo, SAAB-ScaniaCombitech, Bofors) as well as smallerfirms (ErgoventAB, SiTek AB, SEM) and have recently initiated aspin-off company (Samba Sensors AB) for develop-ment of sensors based on original ideas at the depart-ment. Our international connections involve a numberof universities and research institutes.

Thedepartementrepresentsabroadactivity withinthe silicon technology area and is organized in fourgroups as shown below and on the following pages.Our aims are to keep close contact with the interna-tional research community, create relevant knowl-edge for the established companies in Sweden andeven to be a seed for ideas which can be transferredto novel technical business.

AddressDepartment of Solid iState ElectronicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 1860Fax+46 31 772 3622

StaffSenior membersEngström OlofJeppson KjellChristensson SvenBengtsson StefanAndersson GertAndersson MatsHedenstiema Nils

Graduate studentsKarlsson PeterXiao ZhaohuaJauhiainen AndersSveinbjömsson EinarLiss BoLundgren PerEricsson PerBergh MatsRagnarsson Lars-Åke

professor/prefekthögskolelektorhögskolelektorforskarass.lab managerl:eforskn. ing.l:eforskn. ing.

tekn. lic.tekn. lic.tekn. lic.tekn. lic.tekn. lic.civ. ing.civ. ing.civ. ing.civ. ing.

tekn.tekn.tekn.tekn.tekn.tekn.tekn.

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Technology

Gert Andersson\. J

Solid State Electronics

/ "\Design

Kjell Jeppson^ J

Processes

Stefan BengtssonV J

Materials

Mats Anderssonv )

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New enterprises The Internationalresearch community

148 THE CENTRE FOR

SOLID STATE ELECTRONICS

Technical staffLarsson RickardVidovic' NevioBergqvist RoyAndersson ChristerAndersson JanVormbrock Horst

SecretaryWerme Annika

civ. ingciv. ingciv. inging.ing.techn.

Major InstrumentationSilicon processing equipmentContact: Gert Andersson (phone 772 19 15)

With the implementation of the strategy mentionedabove the department has to its disposal the wholechain of equipment from CAD to circuit manufac-turing. Equipment for mask generation, step andrepeat, etc. arc located in the mask laboratory indirect connection to the main process lab.The Silicon Technology Laboratory facilitates: fur-naces for oxidation, diffusion and annealing; apolysilicon LPCVD; an atmospheric pressure CVD(Vapox); a plasma etcher, evaporation equipment, aDC/RF magnetron sputter; lithography equipment;optical and IR-microscopy; a surface profiler;anisotropical etch capabilities; wet chemistry inclean benches, etc.

Electrical measurements etc.Contact: Mats Andersson (phone 772 18 78)

• Computerized HP and Keithley equipment forelectrical measurements such as current-voltage, capacitance-voltage, noise spectra anddeep level transient spectroscopy (DLTS).

• Liquid helium continuous flow optical cryostatand infrared spectrometer

• Three closed-cycle compressed-He opticalcryostats

• Park Scientific Instruments air STM/AFM

Major Reids of ResearchA: Silicon technology laboratory

Employees: lab manager Gert I Andersson,tekn. dr. Rickard Larsson, civ. ing. RoyBergqvist, civ. ing. Christer Andersson, ing.Horst Vormbrock

B: Silicon based insulator-semiconductorstructuresParticipants: professor Olof Engström, tekn. dr.Mats Andersson, tekn. dr. Bo Liss, civ. ing. PerLundgren, civ. ing. Lars-Åke Ragnarsson, civ.ing.

C: Semiconductor wafer bondingParticipants: professor Olof Engström, tekn.dr., Stefan Bengtsson, tekn. dr., AndersJauhiainen, tekn. lie, Per Ericsson, civ. ing.,Mats Bergh, civ. ing.

D: Integrated circuit designParticipants: högskolelektor Kjell Jeppson,tekn. dr., högskolelektor Sven Christensson,tekn. dr., Nils Hedenstierna, tekn. dr., PeterKarlsson, tekn. lie.

Research Projects

A: Silicon technology laboratoryThe Silicon Technology Laboratory has three mainobjectives. First it should be able to supply thetechnological knowledge to fabricate experimentalstructures within the component and micromechnicalsensor research areas. Second the Silicon Technol-ogy Laboratory should develop process technologyfor silicon manufacturing, and finally but not least bea basic resource for silicon process technology atChalmers and in the region of Göteborg. The projectstrategy from the beginning was to create a processline for a metal gate 5 |im CMOS process. With thisstrategy the Lab has the main basic set-up for manydifferent research activities. The first working cir-cuits were produced during 1987. Since then theprocess capabilities in the Silicon Technology Labo-ratory have been extended and refined.

Almost all the different research structures thathave been investiga.ed in the research groups havebeen fabricated in the Silicon Technology Labora-



tory. Furthermore, the laboratory staff is continu-ously running development projects related to indus-try and occasionally minor scale production; pres-ently for Volvo, Bofors, SAAB Combitech AB,SEM, Ergovent, and Samba Sensors AB.

The structures processed in the Silicon Technol-ogy Laboratory for different projects are fabricatedin close co-operation between laboratory staff andthe scientists. The detailed project description isfound in the description of the relevant group. Thelaboratory is presently involved in processing otresearch and prototype structures for the followingprojects:

• Silicon based insulator-semiconductorstructures

• Atomic bonded materials (Si-Si, Si-SiC>2,SiO2-SiO2, Si-Diamond, etc.)

• A novel component for storage and processingof optical information

• Surface protection of power components(Oxygen doped polysilicon)

• Process induced defects in semiconductorcomponents

• Gettering processes in silicon• Micromechanical structures and sensors in

silicon:- Pressure sensor for high temperatures

(optical sensing)- Pressure sensor for low pressure ranges

(electrical and/or optical sensing)- Electric field sensible sensor with

an optical output signal- One-axial accelerometer

(piezoresistive sensing)- Three-axial accelerometer

(piezoresistive sensing)- A monolithic gyroscope in silicon

with an electrical output signal• Development of deposition technology

(Sputtering of various materials)

B: Silicon based Insulator-semiconductorstructures

The function of the insulator-semiconductor inter-face in metal-insulator-semiconductor (MIS) de-vices is crucial to many applications in modemelectronics. Recognizing this, we focus our attentionto the electrical properties of thin oxide, 2-100 nm,

silicon dioxide based insulator silicon structures.We devote the work to defects and degradationphenomena caused by electrical and thermal stressof devices. The measurement methods currently inuse includecapacitance-voltage (C-V), current-volt-age (1- V), noise measurements. Scanning TunnelingMicroscopy (STM), Scanning TunnelingSpectroscopy, and Atomic Force Microscopy (AFM).The test objects are mainly produced in the silicontechnology laboratory at the department. We aim tomaintain a balance between work in pure and appliedprojects in silicon-based technologies. One exampleof the applied work is the collaboration project withABB HAFO on the influence of processing condi-tions on the electrical quality of the oxides. Thus, wealso have access to devices produced in a commer-cial environment, but still suitable for our experi-ments. In a new project, we will expand our knowl-edge into the properties of insulators produced usingRemote Plasma Enhanced Chemical Vapor Deposi-tion (RPECVD). Ultra-High Vacuum equipment forthis purpose will be installed at the department inNovember 1993.

Annealing and charging of metal-tunneloxide-silicon (MTOS) diodesIn recent years, we have studied the charging andannealing properties of ultra-thin (2-3.5 nm) oxideMTOS devices with polycrystalline silicon andaluminum gates [ 1 -51. This was made using I-V andcurrent density-time (J-t) measurements on smalldevices. Among other findings, we have discoveredthat only the aluminum gate devices respond signifi-cantly to post-metallization annealing (PMA) andcan be charged negatively after electrical stress atlow voltages, whereas devices fabricated using bothgate materials can be charged positively duringelectrical stress. Now, by increasing the device area,we can also apply C-V measurements, enabling us tobetter distinguish between different typesof charges.We have demonstrated |6,7| that PMA of aluminumgate metal-oxide-silicon tunnel diodes can be suc-cessfully used to anneal fast interface states even inthe 2-3.5 nm oxide range. The PMA also removes aparallel negative voltage shift. The observed nega-tivecharging during low-vol tage stress of unannealedsamples involves the decrease of the same type ofinterface states as in the PMA, but it does not affectthe parallel negative voltage shift. In contrast, thepositive charging at higher voltages does not affect

150 THE CENTRE FOR


the density of fast states, but is shown to be related toa build-upof slow states in the interfacial region. Ourpreviously obtained result that the rate of positivecharging is not strongly controlled by the flux oftunneling electrons is confirmed by the C-V meas-urements.

Fig. 1AFM gray-scale image of a ~2 nm thickoxide (left part of picture) on silicon (right part ofthe picture). The vertical scale spans from 0(black) to 70 (white) Å.

We have recently obtained and installed a combinedScanning Tunneling Microscope and Atomic ForceMicroscope for operation in an air ambient. Thesehighly sensitive, high-resolving instruments providedetailed information about local properties in theimmediate vicinity of the surface. This is expected togive a very valuable contribution to the evolvingpicture of the charging properties, which we suspectto be influenced to a significant degree by localeffects. Methods are now being developed to usethese powerful instruments for characterization andstress of the oxides. As an example, in Fig. 1 we showan AFM image of a ~2 nm thick oxide (left part ofpicture) on silicon (right part of the picture) afterdipping the oxidized wafer in a hydrofluoric etch.The equipment is also used in a separate project tocorrelate the bonding properties in direct waferbonding to various initial surface treatments.

Analysis and improvement ofdielectrics based on silicon dioxideThis is a collaboration project with ABB HAFO ABand the University of Uppsala. The first undertakingis to characterize and to increase the understandingof the oxidation processes that are crucial to ABBHAFO AB at present. One example is the chargingproperties of the multiply oxidized layers that areused in advanced custom-design circuits. In a secondpart, we aim to improve the electrical properties ofthe oxides by introducing a new technique, nitridationof the silicon dioxides, in a laboratory scale. Theultimate goal of the project is to strengthen thecompetitiveness of ABB HAFO by upgrading theprocessing technology on the base of increasedknowledge. Another important goa' is to increase thecompetence at the universities in the fields of silicontechnology and the physical properties of MIS de-vices.

C: Semiconductor wafer bondingIf the bonded structure is annealed at an elevatedtemperature, the mechanical strength of the bondedinlf two polished silicon surfaces are contacted anadhesive force will develop between them. Thespontaneity of this bonding is strongly correlated tothe smoothnessandcleannessof the surfaces, terfaceincreases, reaching a strength comparable to that ofbulk silicon after annealing at temperatures aboveapproximately 1000° C. Research is performed onthe bonding procedure including the combination ofdifferent materials and on p-operties, mainly electri-cal, of the formed structures and interfaces. Theseactivities are made as a part of the collaborativeproject "BELLA", financially supported by TheSwedish National Board for Industrial and Techni-cal Development (NUTEK).bonded interface at different positions in the oxide(x/d=0.44 and x/d=0.80) and in one reference ca-pacitor.

Electronic properties of interfacesformed by w a f f bondingThe electrical properties of the bonded interfacesformed between silicon and/or oxidized silicon in allthe possible combinations have been investigatedand methods for the characterization have beendeveloped. It was found that the electrical propertiesof bonded silicon - silicon junctions are strongly



dependent on the chemical surface treatment prior towafer contacting. Low-resistive silicon - siliconjunctions require hydrophobic (HF-etched) surfaces.A model for the current transport across bondedsilicon - silicon junctions as well as the capacitanceof these structures has been proposed. A pronouncedcharging was found to occur at orclose to the bondedinterface formed between two oxidized silicon wa-fers when electric fields above 7 M V/cm was appliedacross these oxides. The measurements were per-formed on MOS-structures with a bonded interfacelocated within the oxide. At such high electric fieldscharge carriers are injected from the silicon or themetal contact into the conduction band of the silicondioxide by Fowler-Nordheim tunneling. Figure 1demonstrates the oxide field necessary to maintain aconstant injection current for one reference (stand-ard MOS-structure) and two bonded MOS-capaci-tors. When charges are trapped in the oxide, theelectric field picture in the oxides will change andtherefore the applied bias necessary to maintain aconstant current will change. Thus, a large change inthe applied electric field means a large change in thetrapped oxide charge.

7.010 1 3 10 1 4 10 1 5 101 6

Qjnj (charges/cm2)1017

Fig. 1 Oxide field during charge injection from thesubstrate vs injected charge (current density: 1O5

A/cm2) in two bonded capacitors with the bondedinterface at different positions in the oxide (x/d=0.44 and x/d=0.80) and in one referencecapacitor.

Currently the activities are directed towards investi-gation of silicon dioxide - silicon dioxide interfacesby means of a photo current vs voltage technique.Both bonded materials made in house and commer-cially available materials are investigated. In thismethod charge carriers are injected into the silicondioxide by aid of illumination with UV light. Duringthe illumination a relatively small bias is appliedacross the oxide. It is found that the bonded oxides

are very sensitive to this illumination. As a result theinterface state density at the thermally grown silicon- silicon dioxide increases. An annealing of thestructure at 425° C in presence of hydrogen againreduces the density of interface states. The increaseand decrease of the density of interface states can bemade in several cycles of illumination and anneal-ing, indicating a role of hydrogen atoms in theobserved phenomena. We are also planning to useSecondary Ion MassSpectroscopy (SIMS) tocharac-terize the regions surrounding different bonded in-terfaces. This will be made together with SIMS-labat the Physics Department, Chalmers.

The formation of sllicon-orKJIamond materialsby wafer bondingThe objective of this project is to investigate ifpolycrystalline diamond can be used as the buriedinsulator in Silicon-On-Insulator (SOI)-materialsinstead of the conventional silicon dioxide. We areplanning to manufacture Silicon-On-Diamond(SOD)-materials by means of wafer bonding. Theadvantage of using diamond instead of silicon diox-ide comes in terms of thermal conductivity. Whencritical device dimensions are decreased and circuitfrequencies are increased self-heating of SOI-de-vices will become an increasing problem. Diamondhas a thermal conductivity which is of the order of1000 times higher than that of silicon dioxide. How-ever, to be useful the diamond films must exhibit ahigh resistivity, low probability of charge trapping,high breakdown integrity and having interfaces tosilicon with acceptable properties in terms of charg-ing, interface states etc. Currently we are investigat-ing the electrical characteristics of thin diamondfilms (thickness: 1 - 3 nm). The diamond films aredeposited by CVD-methods and the films are avail-able for the Department of Solid State Electronicsthrough a collaboration with Diamonex Inc, USAand with the Department of Inorganic Chemistry atUppsala University. Figure 2 demonstrates the con-ductance vs voltage characteristics at different tem-peratures of a structure consisting of an 1.9 urnpolycrystalline diamond film on top of an n-typesilicon wafer. The conductivity shows an ohmic-likebehavior at low voltages and a field activated regionat higher voltages. The large signal resistivity calcu-lated at an applied bias of 50 V is of the order of 101 ]

flcm.

152 THE CENTRE FOR


Basic research on the fundamentalsof wafer bondingWork is also made to increase the understanding ofthe conditions required for a successful bonding aswell as on a generalization of the bonding techniqueto other materials than silicon and silicon dioxide.These activities are aimed to increase theunderstandings of the wafer bonding phenomena aswell as of the requirements for successful bonding ofdifferent materials. Some important parameters inthis context are the morphology of the surfaces andthe cleaning procedures prior to wafer contacting.The question of surface morphology will be ad-dressed by the use of a surface profilometer (alpha-stepper) and an Atomic Force Microscope (AFM)available at the Department. The chemical treatmentof the wafer surfaces prior to wafer contacting isimportant for the spontaneity of the bonding as wellas for the properties of the formed interfaces. Differ-ent wet chemical treatments aid plasma treatmentsof the wafer surfaces will be investigated. The plasmacleaning and preparation procedures can be made ina new ultra-high vacuum (UHV) system for deposi-tion of high quality insulators which will be deliv-ered in November 1993. This system is a remoteplasma enhanced chemical vapor deposition(RPECVD) reactor. The primary objective is toproduce insulators with an electrical quality equal toor comparable to that obtained in conventional,thermal oxidation, but at a much lower temperature;-300° C as compared to -1000° C, but it can as wellbe used for the preparation of hydrogen terminatedsilicon surfaces.

•100 -75 -50 -25 0 25 50 75 100Gata voltage (V)

Fig. 2 The conductance vs gate voltage for an Al-diamond-silicon device. The thickness of thepolyerystalline diamond film was about 1.9 am.The curves corresponds to different temperatures.

Publications 1991/1992

Ph. D. DissertationsM.O.Andersson: "Characterization and modeling of

electrically active point defects in silicon/silicondioxide structures", 1991

S.Bcngtsson: "Preparation and electrical characterization ofsilicon structures formed by wafer bonding", 1991

CLAndersson: "Electrical properties of process induceddefects in silicon junctions", 1992

Licentiate DissertationsRKarlsson: "Direct extraction of DC-parameters for MOS

transistor models", 1991

Diploma worksP.Lundgrcn: "Si-SiO2 interface trap annealing in metal-

tunnel oxide semiconductor (MTOS) devices", 1991

T.Stcmmc: "En datoriserad mätmetod för bestämning av enkisclstrukturs resonansegenskaper", 1991

Reports and artides1. G.I. Andersson and O. Engström,

Forward bias tunneling at defect clusters in siliconemitter junctionsJ.Appl.Phys. 69,4418 (1991)

2. A. Ricksand and O. EngströmDeep level transient spectroscopy: Increased accuracyof interpretation of silicon silicon dioxide interfacestate data by the assistance of computer simulationsJ.Appl.Phys., 70,6915 (1991)

3. A. Ricksand and O. EngströmThermally activated capture of charge carriers intoirradiation induced Si/SiO2 interface statesJ.Appl.Phys., 70,6927 (1991)

4. MO. Andersson, K.R. Farmer and O. EngströmNegative charging in ultra-thin mctal-oxidc-silicontunnel diodesJ. Appl. Phys.,71,1846 (1992)

5. S. Bengtsson, G.I. Andersson, MO. Andersson and O.EngströmThe bonded uni-polar silicon-silicon junctionJ.Appl.Phys. 72,124(1992)

6. K.R. Farmer, M.O. Andersson and O. EngströmTunnel electron induced charge generation in very thinsilicon oxide dielectricsAppl. Phys. Lett., 58,2666 (1991)



7. K.R. Farmer, M.O. Andersson and O. EngströmTime dependent positive charge generation in very thinsilicon oxide dielectricsAppl. Phys. LetL, 60,730 (1992)

8. S. Bengtsson and O. Engström,Electrical methods for the characterization of bondedsilicon/silicon interfacesJap. J. Applied Physics, 20,356 (1991)

9. B. Liss, A. Lindgren and O. EngströmCharging properties of SIPOS used as a passivationlayer on siliconMicroelectronic Engineering 15,125 (1991)

10. A. Dejenfelt and O.EngströmMOSFET channel mobility degradation as a result ofFowler-Nordheim electron injectionMicroelectronic Engineering 15,461 (1991)

11. E.Ö.Sveinbjömsson and O.EngströmTransformation of gold in n-type silicon from a newdeep level to the gold acceptor levelMaLRes.Soc.Symp. Proc. 262, (1992) in press

12. S. Bengtsson, A. Jauhiainen and O.Engström 18)Oxide degradation of wafer bonded MOS capacitorsfollowing Fowler-Nordheim electron injectionJElectrochem. Soc., 1992, in press

13. S.BengtssonSemiconductor wafer bonding. A review of interfacialproperties and applicationsJ£l.MaL, 1992, in press

14. P.T.Landsberg and O.EngströmSemiconductor statisticsHandbook of Semiconductors, Vol.1 (Elscvicr, 1992),in press

15. G.I. Andersson, M.O. Andersson and O. EngströmDiscrete conductance fluctuations in silicon emitterjunctions due to defect clustering and evidence forstructural changes by high-energy electron irradiationand annealingJ. Appl. Phys., in press

16. L. Löfdahl, G. Stemme and B.JohanssonReynhold stress measurements using direction sensi-tive double-chip silicon sensorsMeasurement Science and Technology. 2,369 (1991)

17. G.StemmeResonant silicon sensorsJ. Micromechanics and Microengineering, 1,113(1991)

18. Nils Hedcnsticma and Kjell O. Jcppson,Comment on 'A Module Generator for OptimizedCMOS Buffers'IEEE Transactions on CAD of Integrated Circuits andSystems, CAD-11, No 7,1992

19. Nils Hedenstierna and Kjell O. JcppsonThe Halo Algorithm - An Algorithm for HierarchicalDesign Rule Checking of VLSI Circuits,IEEE Transactions on CAD of Integrated Circuits andSystems, CAD-11, No 10,1992 in press

20. Kjell O. Jcppson, Sven Christcnsson and NilsHedenstiemaFormal Definitions of Geometric Design RulesIEEE Transactions on CAD of Integrated Circuits andSystems, in press

21. Peter R. Karlsson and Kjell O. JcppsonAn Efficient Parameter Extraction Algorithm for MOSTransistor ModelsIEEE Transactions on Electron Devices, ED-39, No 9,1992, in press

22. AT. Dcjcnfelt and O. Engström,MOSFET degradation following Fowler-Nordheimelectron injectionManuscript 1991, submitted to IEEE Trans. Electron.Dcv.

23. AT. Dcjenfelt,Modeling impact ionizau'on in Si and hot electroninjection into SiOsdo3(2) in a spatially varying electricfield by the direct integration methodManuscript 1991

24. E.Ö.Sveinbjörnsson and O.EngströmA novel hydrogen-gold related deep acceptor in N-typcsiliconManuscript, 1992, submitted to Appl.Phys.Lctl.

25. O. Engström, S. Bengtsson, G.I.Andcrsson,M.O.Andersson and AJauhiaincnElectrical characterization of bonding interfacesManuscript, 1992, submitted to J.Electrochcm.Soc.

26. O.Engström and H.RichcrtFiberoptisk tryckgivarcSvensk patentansökan, inlämnad till Patent- ochregistgrcringsverket

27. P.R.Karlsson and K.0 JcppsonExtraction of series resistance indepenent MOStranistor parametersManuscript, 1992, subm. to IEEE Elctron. Dev. Lett.

28. P.R.Karlsson and K.OJeppsonA direct extraction algorithm for a submicron MOStransistor modelManuscript, 1992, subm. to ICMTS 93

154 THE CENTRE FOR


29. N.Hcdcnslicnia and K.OJeppsonComments on the CMOS tapered buffer bufferproblemManuscript, 1992

30. K.OJeppsonModeling the influence of the transistor gain ratio andthe Miller capacitance on the CMOS inverter rampdelayManuscript, 1992

31. M.O. Andersson, KR. Farmer and O.EngströmElectron trapping-induced conductance and noisedynamics in ultra-thin melal-oxide-silicon diodesProc. International Conference on Insulating Films onSemiconductors,Liverpool, 1991

32. KR. FarmerRandom telegraph signals and related phenomena inMOS device structuresProc. International Conference on Insulating Films onSemiconductors,Liverpool, 1991 (Invited)

33. A. Dcjcnfclt and O. EngströmMOSFET channel mobility degradation as a result ofFowlcr-Nordheim electron injectionProc. 21st European Solid Stale Device Conference(ESSDERC '91), Montreaux, 1991

34. B. Liss, A. Lindgren and O. EngströmCharging properties of SIPOS used as a passivationlayer on siliconProc. 21st European Solid Slate Device Conference(ESSDERC '91), Montreaux, 1991

35. S. Bengtsson, A. Jauhiainen and O. EngströmOxide degradation of wafer bonded MOS capacitorsfollowing Fowler-Nordheim electron injectionProc. First International Symposium on SemiconductorWafer Bonding Science,Phoenix, Arizona, 1991

36. O. Engström and S. BengtssonElectrical characterization of bonding interfacesProc. First International Symposium on SemiconductorWafer Bonding Science,Phoenix, Arizona 1991, (Invited)

37. K.R.Farmcr, M.O.Andcrsson, PLundgren andO.EngströmTime-dependent charging in aluminum andpolycristalline silicon gate metal-tunnel oxide- silicondiodesIEEE Semiconductor Interface Specialists Conference,Lake Buena Vista, Florida, 1991

38. P.Lundgrcn, K.R.Farmcr, M.O.Andcrsson andO.EngströmCreation and annihilation of charge states in mcial-oxidc-silicon tunnel diodesProc. 15th Nordic semiconductor meeting,Hämecnlinna, Finland, 1992, p.261

39. A Jauhiainen, S.Bengtsson and O.EngströmCharging phenomena at SiO2-SiO2 interfaces formedby wafer bondingProc. 15th Nordic semiconductor meeting,Hämecnlinna, Finland, 1992, p.265

40. S.Bengtsson, G.I.Andersson, M.O.Andersson ochO .EngströmDefects in bonded silicon-silicon structuresProc. 12th General Conf. of the Condcnccd MatterDivision, Prag, April, 1992

41. A Jauhiainen, S .Bengtsson and O.EngströmCharge trapping in wafer bonded MOS structuresManuscript, 1992, to be presented at ESSDERC '92

42. Z.Xiao, S.Norrman and O.EngströmA fibcroptical voltage sensor prepared bynicromachining and thermal bondingManuscript 1992, submitted to IEDM, 1992

43. G. Slcmmc and E. SlemmcA capacitivcly excited and detected resonant pressuresensor with temperature compensationProc. Eurosensors '91, Rome, 1991

44. G. StemmcResonant silicon sensorsFurosensors '91, Rome, 1991 (Invited)

45. Kjell O JeppsonAn improved timing model for the CMOS inverterProceedings of the 1991 European Conference onCircuit Theory and Design (ECCTD-91), pp 567-576,Copenhagen, September 2-6,1991

46. Kjell O. Jeppson, Sven Christcnsson and NilsHedcnsticrnaFormal definitions of geometric design rulesProceedings of the Norsilc/Norchip Seminar 1991,paper 10, Copenhagen, October 1991

47. Nils Hedcnslierna and Kjell O JeppsonA parallel hierarchical design rule checkerProceedings of the 1992 European Conference onDesign Automation (EDAC '92), pp 142-146, Brus-sels, March 1992



48. Peter R. Karlsson and Kjell O. JeppsonAn analytical strategy for fast extraction of MOStransistor DC parameters applied to the SPICE MOS3and BSIM modelsProceedings of the International Conference onMicroelectronics Test Chips (ICMTS-92), pp 78-83,San Diego, March 1992

49. Peter R. Karlsson and Kjell O. JeppsonInfluence of the series resistance on extracted MOStransistor parametersProceedings of the 15th Nordic SemiconductorMeeting, pp 175-178, Hämeenlinna, June 1992

156 THE CENTRE FOR

Semiconductor Physics andHeterostructures

Research SummaryThe research is foe used on quantum structures basedon III-V semiconductor materials with motivation todevelopaphysicalunderstandingofquantumeffectsin artificially layered materials and demonstration ofnew device concepts. The work comprises growthby molecular beam epitaxy and studies of structural,electrical and optical properties of semiconductorquantum structures. One theme is studies of physicaleffects as a result of charge confinement in artifi-cially layered materials. Other fields are limitationsof the MBE technique such as conditions for growthof high purity material, growth of narrow quantumwells (QW) with arbitrary shape and multiple —coupled and uncoupled — wells, superlattices andlayered growth of lattice mismatched materials.

Physical characteristics of semiconductors de-pend on their electronic band structure. The directband gap and high electron mobility in III-V com-pound materials, as a contrast to silicon, are em-ployed in optical and high frequency devices. Inartificially layered structures new phenomena, dif-ferent from the hulk, are introduced. Quantum struc-tures provide an addition.' freedom in tailoring thematerial to a predicted characteristic.

Lattice mismatched semiconductor layers give apossibility to use the strain to tailor-make the physi-cal properties of importance for electronic andoptoelectronic devices. An obvious limitation is thecritical layer thickness. We have used lattice mis-matched InxGal-xAs/GaAs as a model system forstudies of such strained heterostructures.

The most prominent commercial devices grownby MBE are quantum well structures for laser diodesin CD players and the GaAs/AlGaAs HEMT-tran-sistors in high frequency system such as mobiletelephones, satellite antennas, TV-sets, GPS naviga-tion receivers, etc.

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31 772 3308Fax +46 31772 3385

StaffSenior Members:Thorvald AnderssonGösta Swenson

Graduate Students:Weiquan ChenMichael EkenstedtJöran Roslund

docent/ass profdocent/ass prof

fil licfil licciv ing

Pong Songpongs (part time) M ScShumin Wang

Diploma workersTapas Ganguli

Technical Staff:Håkan MillquistLars-Åke SidenbergJan Thordsson

tekn lic

instr.mak.ing.fil kand

Major Instrumentation• Molecular beam epitaxy system, a modified

Varian MBE 360, for growth of III-V com-pounds with Al, Ga, In, As and Sb. The systemis equipped with arsenic and antimony crackerfurnaces and 2" rotating substrate holder forIn-free and In-mounting. The MBE-systemalso has Auger, RHEED, a mechanical probefor accurate substrate (contact) temperaturemeasureme. ts and a mass spectrometer.

• Molecular beam epitaxy system, Varian gen IImodular, for growth of high purity III-Vcompounds from Al, Ga, In and As. The


SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES

system is equipped with 3" rotating substrateholder for In-free and In-mounting, separatecryo pump, RHEED, mass spectrometer and acleavage chamber.

Optical analysis instrumentation for photo-luminescence (PL) and photo currentspectroscopy, photoluminescence excitationspectroscopy, photoreflectance spectroscopyand absorption measurements.

Electrical characterisation equipment for Halleffect, CV-, IV- and DLTS measurements aswell as electrochemical profiling and measure-ments in magnetic fields.

Financial SupportNutekNFRTFRFRNKnut and Alice Wallenberg FoundationSkandinaviska Enskilda Banken

Major Reids of ResearchA: Lattice Mismatched Layer Structures

participants: Thorvald Andersson, MichaelEkenstedt and Shumin Wang,collaborators: J-Y Jao and G Dunlop

B: MBE Growth and assessment of High Mobil-ity Materialparticipants: Thorvald Andersson, MichaelEkenstedt, Gösta Swensson, Jan Thordssonand Shumin Wang.

C: Arbitrarily Shaped Quantum Wells,participants: Thorvald Andersson, WeiquanChen, Jan Thordsson and Shumin Wang.

D: Strained Quantum Wellsparticipants: Thorvald Andersson, WeiquanChen, Michael Ekenstedt, Jöran Roslund,Pong, Songpongs and Shumin Wang,collaborators: V D Kulakovskii

Research Projects

A Lattice Mismatched Layer StructuresA large number of III-V compound semiconductorscan be combined from the 9 binaries. Four of theseare lattice matched better than ~ 0.7 %; GaAs/AlxGai_xAs, In 53Ga.47As/InP, InAs/GaSb andGaSb/AlxGai.xSb.Onlytherwofirstheterostructureshave a major practical use. If high quality latticemismatched epitaxial layers could be grown thenumber of heterostructures fordexice purposes wouldbe greatly extended.

In lattice mismatched structures, misfit disloca-tions or three dimensional (3D) growth share themisfit with the strain at a certain critical layer thick-ness (CUT). The presence of dislocations can bedetected by electrical and optical measurementssince they act as scattering centres and decrease bothelectron mobility and luminescence efficiency. Intransmission electron microscopy individual dislo-cations can be observed. If the misfit is larger thanapproximately 2 % the growth mode switches at aCLT from two dimensional (2D) layer by layergrowth to a 3D growth where islands form on thegrowth surface. These islands cause increased inter-face roughening and deterioration of both electricaland optical properties. The project has aimed toobtain a deeper insight into the problems related withthe CLT in the InxGa j ,x As/GaAs and Sb-compoundson GaAs. The currentinterestinSb-compounds withsmall band gap and high mobility, such as InSb andits alloys InxGal-xSb and InAsxSbi.x, is a conse-quence of potential applications in light emitting IR-devices, IR-detectors, high frequency eleccronicsand magnetic Hall devices.

A l : Critical Layer ThicknessThe microstructure of lattice mismatched strainedlayers of InxGa l-\As in GaAs has been studied byTEM. Samples were grown by MBE at which twoparameters were varied: the composition, x, and thelayer thickness. The thickness was controlled on themonolayer scale such that the strained InxGa 1-xAslayers were a few atomic monolayers. After thepreparation of cross section and plan view samplesthe microstructure was studied in the bright field,dark field and weak beam modes. Layers thinnerthan a certain thickness, the critical layer thickness(CLT), showed homogeneous contrast indicating

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that the InxGal-xAs layers were homogeneouslystrained with flat interfaces. The CLT was defined asthe thickness for the onset of features in the TEMmicrographs. For x<0.3 dislocations developed atthe CLT while 3-dimensional growth started beforedislocation generation for x>0.3. For InAs layersembedded in GaAs only the first monolayer is defectfree.

The onset of 3D growth, t3D, has been measuredas a function of both substrate temperature andcomposition and was found todecrease with increas-ing In content and growth temperature.Photoluminescence measurements have been usedto investigate interface roughening caused by 3Dgrowth and to give an estimate of the island size. Themobility in thick InxGai.xAs layers grown latticemismatched on GaAs was studied as a function ofcomposition, layer thickness and growth tempera-ture. Recent and ongoing investigations concernstrain mediation in a double quantum well structurefrom a strained Ino.36Gao.64As layer through a GaAsbarrier. The results show an increasing strain media-tion with decreasing barrier thickness.

For growth of InxGal-xSb on inexpensivesubstrates such as GaAs, the difference in latticeconstant, Da/a ~ 7 to 14 % depending on the compo-sition, introduces a large strain in the thin layers.Dislocation generation and multiplication occur af-ter a few monolayers when the lattice mismatch canno ionger be accommodated only by biaxial strain.The CLT has been investigated for InxGal-xSblayers grown on GaAs by MBE for the full range ofcomposition. Both PL and TEM were used to studythe CLT as a function of In-mole fraction. The resultsindicate an increasing CLT for increasing In-contentthat is contradictory to results normally found instrained systems and predictions from theory.

A2: Interface between LatticeMismatched Layers.

During growth of lattice mismatched layers defectsare formed at the interface and at the growth front. Tounderstand the physical conditions of dislocationgeneration and 3D-growth we used the layer thick-ness, strain and growth temperature as parameters inInxGa|.xAs/GaAs growth to detect the transitionfrom layer-by-layer to 3D growth.

B MBE Growth of High Purity MaterialThe preparation of high quality materials is of great-est importance for material research and deviceapplications. The purity is usually described in termsof mobility and sharpness of PL-peaks.

B l : Bulk GaAs and AlxGal-xAs/GaAsHeterostmctures

We used As4 to achieve very high electron mobilityin both bulk GaAs and selectively doped AlxGal-xAs/GaAs heterostructures. Special efforts weremade in baking, outgasing and sample preparationsto minimise the background impurity level. Struc-tures were characterised by Hall-effect measure-ments between lOand 300K and Shubnikovde Haasand photoluminescence measurements at 4.2 K. Thebest mobility was 2.54x105 cm2/Vs with a freecarrier concentration below lxlO14 cm-3 for bulkGaAs at 42 K. These values are comparable to thebest mobility resultseverreported:2.95xl05cm2/Vsfor bulk GaAs. For a 2-DEG the mobility was 2x 106cm2/Vs at an electron concentration of 2x1011 cm-2 at 4.2 K. The low background impurity levelindicated a very clean MBE system suitable forgrowth of high quality device materials.

B2: InxGal-xAs/lriyAli^As Heterostructures

Lattice matched structures of InxGal-xAs/InxAlj.xAs (x > 0.5) on InP have demonstrated very gooddevice propeties. The reason is that the high In-content provides large values of both electron mobil-ity and band offset. Structures based on phosphorousarcusually grown by MOCVD (metal organic chemi-cal vapour deposition) since there are pronounceddifficulties with P in connection with MBE. If In-compounds instead could be grown on GaAs suchdevices could be integrated with GaAs IC-technol-ogy. The InxGai.xAs/GaAs heterostructure is sup-posed to be a good material candidate for highelectron mobility transistors. However, because ofthe lattice mismatch the In composition is limited;typically x <0.3. By introducing InxAlyGal-x.yAsin the barrier and/or buffer layers, the In compositionin the 2-DEG channel can be increased to a highervalue. We have used different layered structures tomanipulate the channel in order to improve theconduction in basically lattice mismatched systems.We have grown both conventional InxGai .xAs/GaAsHEMT structures (x=0.15 to 0.25) and structureswith x=0.8 and 1 using the InxAlyGal-x.yAs buffer



layer. The mobility improved with x. We also testedthe effect of a short period In As/GaAs superlattice inthe channel region to further reduce alloy scattering.From Hall measurements, it was found that theelectron mobility increased by 10 % with the inser-tion of this superlattice. Typical mobility values at 77Kwas 15000 cm2/Vsorhigherwith2-DEG concen-trations of ~ 2xl012 cm-2.

C Quantum Well LayersThe MBE process allows atomic layer-by-layergrowth with monolayer resolution. Therefore verythin layers with high uniformity and precise compo-sition can be grown. Quantum well (QW) structuresare single or multiple layered structures where indi-vidual layers are thin enough to introduce quantumeffects. Thicknesses are typically monolayers to-200 Å.

C l : Calculation of Confined LevelsCalculations of the confined electron and hole statesare very important when employing the quantumeffects in electronic and optical devices. We haveestablished a numerical method to calculate energylevels and wave functions in arbitrarily shaped quan-tum wells. The model includes the nonparabolicityeffect and a position dependent effective mass andcan be used for single as well as coupled QWs. TheSchrödinger equation was solved for a seriej ofdifferently shaped wells to compare their interbandand intersubband transitions under an applied elec-tric field. From these calculations, we obtained theknowledge on how to design structures by control-ling the confined levels and wavefunctions.

C2: Quantum-Confined Stark EffectThe quantum-confined Stark effect is a shift (Starkshift) of the exciton absorption edge to lower energywith an electric field applied over a semiconductorquantum well. This effect offers a tuneable opticalresponse which can be used for a number of impor-tant device applications, such as high-speed opticalmodulators and photodetectors. The Schrödingerequation was solved for arbitrarily shaped quantumwells so transition energies could be calculated.From this the observed Stark effect in a number ofdifferently shaped quantum wells grown by MBEcould be described. Based on calculations of theStark effect we suggested two novel structures; the

two-step QW and inverse parabolic QW. These weregrown by MBE and measured by photoluminescenceandphotocurrenttechniques. Large Stark shifts werefound in the experiments, in good agreement withour theoretical predictions.

C3: Aifoitrarlly Shaped Quantum WellsArbitrarily shaped semiconductor quantum wells asa contrast to conventional square ones exhibit inter-esting physical phenomena of possible use in de-vices. Growth of such structures demands a goodcontrol of alloy compositions within a certain thick-ness, which is a challenge for MBE. We haverecently succeeded in growing wide AlGaAs/GaAsparabolic quantum wells (PQWs), inverse PQWs(IPQW) and narrow triangular quantum wells (TQW)by MBE using digital, compositional grading andmigration enhanced epitaxy techniques. For widePQWs, we found that a linear ramp of the Al sourcetemperature was a good approximation to fulfil thedesired potential shape. The quantum well shapewas further t »nfirmed by low temperaturephotoluminescence showing an equal energy sepa-ration between neighbouring interband transitions.Digital, compositional grading and migration en-hanced epitaxy techniques were used for growth ofnarrow, < 150Å, triangular QWs and inverse PQWs.The compositional variation was controlled by insitu monitoring the Al source temperature during thegrowth. Secondary ion mass spectroscopy was usedto check the composition depth profile and revealedthe desired shape with very good quality.Photoluminescence, photocurrent and Hall effectmeasurements were employed to characterise opti-cal and transport properties. It was found that struc-tures grown by the digital method had better opticaland transport properties than ones using thecompositional grading method.

D Strained Quantum StructuresThe electronic structure of quantum wells not onlydepends on their shape and size but also on chargedensity and strain. Photolumincscence, in combina-tion H ith hydrostatic pressure and magnetic fieldsperpendicular to the layers, has been used to analysephysical properties of QWs. StudiesofInxGai_xAs/GaAs SQW's by PL revealed the direct-to-indirecttransition with pressure. With magnetophoto-lumi-nescence a new magnetoplasmon-phonon couplingwas observed in dense 2-DEGs.

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Two MBE-systems are used: Vanan MBE-360for Al, Ga, In, As (cracker) and Sb (cracker) andVarian Gen-II Modular for Al, Ga, In and As. TheMBE technique includes equipment for sensitiveRHEED-oscillation detection and leliable measure-ment of growth temperatures from -380 °C. Mate-rial growth is mainly AlxGai_xAs/GaAs, and thelattice mismatched InxGai_xAs/GaAs system butalso to InSb- and GaSb-compounds as well as In As/InGaSb superlattices. Grown materials are charac-terised by electrical and optical methods as well byTEM, SIMS and XRD.

• MBE-systemsVarian MBE-360 and gen-IIModular.

• Optical techniques such as photoluminescence.• Hall effect, IV- and CV- techniques.• Low temperature magnetoresistivity.• Semiconductor processing equipment.

References 1988-1992

Ph.D. DissertationsJi-Yong Yao, 'Transmission Electron Microscopy of

Strained Layer Structures". 1990.Jan Söderström, "Novel III-V Semiconductor Tunnel

Stmclures Grown by Molecular Beam Epitaxy", 1990.

Licentiate DissertationsAli Rouhani-Kallch, "Processing and electrical measure-

ments of mesa- and split gate wires made of n-t-GaAsandAlGaAs/GaAs2-DEG's", 1989.

Malcolm dimming, "Hall Effect Measurements on GaAsand InSb Grown by Molecular Beam Epitaxy, 1991.

Michael Ekenstedt, "The Influence of Growth Temperatureon the Critical Layer Thickness of Suvined In,Gai.xAs/GaAs Hcicrostruclurcs Grown by Molecular BeamEpitaxy", 1991.

Weiquan Chen, "Quantum Confined Stark Effect inDifferent Quantum Well Structures", 1992.

Shumin Wang, "The Band Edge Offset and the CriticalLayer Thickness in III-V Compound SemiconductorHctcrostructures", 1992.

Diploma WorkMichael Ekenstedt," Halleffektmätningar", 1988.Ulf Eriksson, "RHEED-oscillationcr och Mätning av

Substrat-temperatur", 1989.Jan Thordson, "Phololumincsccncc Studies on Ultrathin

Quantum Wells of AIGaAs/GaAs and GaAs/InGaAsGrown by Molecular Beam Epitaxy", 1992.

Niklas Mros, 'Tunnelling Across Single AlGaAs Barriers",1992.

Tomas Holmquist, "Quantum Wire Fabrication by CleavedEdge Overgrowth using MBE", 1993.

Tapas Ganguli, "A Review of High resolution X-rayDiffraction Studies in Semiconductor Supcrlatticcs",1993.

Journal Articles1. Photolumincsccnce and Photoconductivity Measure-

ments on Band Edge Offsets in Strained InxGaixAs -GaAs Quantum Well Hcterostructures Grown byMBE, T. G. Andersson, Z-G. Chen, V. D. Kulakovskii,A. Uddin and J. T. Vallin, Phys. Rev. B3J (1988-1)4032.

2. A Multiple State Memory Cell Based on the ResonantTunnelling Diode, J R Söderström and T G Andersson,IEEE Electronic Device Letters EDL9 (1988) 200.

3. The Geometry of a Gate-Controlled n-n+-n GaAs Wire,P M Rodhc, A Rouhani-Kallch and T G Andersson,Semiconductor Science and Technology 3. (1988) 823.

4. Structure of Lattice-Strained In,Gai xAs/GaAs Layersstudied by Transmission Electron Microscopy, J YYao, T G Andersson and G L Dunlop, AppI Phys Lett.52(1988)1420.

5. GaAs/AlGaAs Resonant Tunnelling Diodes: TheDependence of the Peak-To-Valley Current Ratio onBarrier Thickness and Height, J. Söderström and T. G.Andersson, Superlatticcs and Microstructurcs, 5_ (1988)109.

6. InxGai .xAs Quantum Wells and Band Offset, T GAndersson, SPIE Vol. 243_, Quantum Well andSupcrlaiucc Physics II, (1988) 159.

7. Investigation of High Quality GaAs:In Layers Grownby Molecular Beam Epitaxy, A Uddin and T GAndersson, J. Appl. Phys. & (1989) 3101.

8. Phoioluminesccnce of Residual Shallow Acceptor inIn,Gai.xAs (x<0.24) Grown on GaAs, Z-Y Xu, J-ZXu, T. G. Andersson and Z-G Chen, Solid St. Comm.20(1989)505.

9. Hot Carrier Photolumincscencc from Strained InxGai.aAs/GaAs Single Quantum Wells Structure, T GAndersson, Z-G Chen, Z-Y Xu, J-Z Xu and W-K Gc,J.Cryst Growth 25.(1989)215.

10. Interfacial Microstructurcs in InxGai ,As/GaAsStrained Layer Structures, J. Y. Jao, T. G. Anderssonand G. L. Dunlop, Material Research Symposium Proc.Vol J4S (1989) 303.

11. Renormalisalion of the Carrier Dispersion Law in aDense Electron-Hole System in an InGaAs QuantumWell, L. V. Butov, V. D. Kulakovskii T. G. Anderssonand Z. G. Chen, JETP Lett. 48,(1989) 280.



12. Time-Resolved Photolumincscence from InxGai.xAs/GaAs Single Quantum Well, S Qian, S Yuui, Y Li, TG Andersson, Z Chen, W Peng and Z Yu, Ch. Phys.Leu. fi(1989) 559.

13. A Weak Beam Imaging Technique for the Characteri-sation of Interfacial Roughness in (InGaAs)/GaAsStrained Layer Structures, J. Y. Jao, T. G. Anderssonand G. L. Dunlop, Material Research Soc. Symp. Proc.152(1989)345.

14. Picosecond Spcctroscopy of Hot Carrier Distribution inIn,Gai.xAs/GaAs Strained Single Quantum WellStructures, Z Xu, W Ge, J Xu, B Zheng, Y Li, T GAndersson and Z-G Chen, Chinese Journal of Infraredand Millimeter Waves 8 (1989) 137.

15. Influence of Thermal Annealing on Deep Levels inMBE-Grown High Purity GaAs Thin Films, H-D Xuand T G Andersson, Chinese Journal of Semiconduc-tors 11 (1989) 31.

16. The Thermalization of Photoexcited Hot Carriers inInxGai.xAs/GaAs Strained Single Quantum WellStructures, Z Xu, W Ge, J Xu, Y Li, B Zheng, T GAndersson and Z-G Chen, Superlatliccs and Micro-structures 2 (1990) 13.

17. Localisation Effects, Energy Relaxation and Electronand Hole Dispersion in Selectively Doped n-AlyGa|.yAs/InxGai.xAs/GaAs Quantum Wells, L V Butov, VD Kulakovskii, T G Andersson and Z-G Chen, Phys.Rev. B42 (1990) 9472.

18. Photolumincscence of a Dense Quasi-2D Electron-Hole System in a Modulation-Doped Hctcrostructurcwith Strained InGaAs QW, LV Butov, VDKulakovskii and TG Andersson, Phys. Stat. Solidi, 15J)(1990) 165.

19. Phototransmission Study of Strained-layer InxGa|.xAs/GaAs Single Quantum Well Structures, S. Yuan, S.Wang, S. Qian, Y. Li, T. G. Andersson and Z-G Chen,J. Appl. Phys. 6S (1990) 5388.

20. Thickness Dependent Migration of Au Films, G Pctö,T Lohner, L Pogäny and T G Andersson, Vacuum, 4J.(1990)1128.

21. Magnetic field Increased LO-phonon Raman Scatter-ing in Selectively Doped n-AIGaAs/GaAs QuantumWells, L V Butov, V D Kulakovskii, B N Shepcl and TG Andersson, Superlatticcs and Microstructurcs 16(1991)265.

22. Critical Layer Thickness in InxGa|.xAs/GaAs Quan-tum Wells Studied by Photolumincsccncc and Trans-mission Electron Microscopy, S M Wang, T GAndersson, V D Kulakovskii and J-Y Yao,Supcrlatticcs and Microstructurcs 2 (1991) 123.

23. Growth and Characterisation of High-Current DensityHigh-Speed In As/AlSb Resonant-Tunnelling Diodes, JR Söderström, E R Brown, C D Parker, L J Mahoney, JY Yao, T G Andersson and T C McGill, Appl. Phys.Lett. 51(1991)275.

24. Characterisation of Interfacial Topography in LatticeStrained InxGai.xAs/CaAs Heterostructures by theWeak Beam Imaging Technique, J Y Yao, T GAndersson and G L Dunlop, Phil. Mag. A64 (1991)173.

25. The Interfacial Morphology of Strained EpitaxialInxGai.xAs/GaAs, J Y Yao, T G Andersson and G LDunlop, J. Appl. Phys. 62 (1991) 2224.

26. Many-body Effects of a Dense 2D Electron-HoleSystem in a Strained InxGai-xAs/GaAs Quantum Well,L V Butov, V D Kulakovskii and T G Andersson,Phys Rev. B44 (1991) 1692.

27. Photon-Assisted Resonant Tunnelling through Vari-ably Spaced Supcrlatticc Energy Filters, A Larsson, SIBorenslain, B Jonsson, I Andersson, J Wcstin and T GAndersson, Appl. Phys. Lett. 5j£ (1991) 1297.

28. Long Wavelength Infrared Spcctroscopy of an Asym-metrically Structured Ga.6AI 4As/GaAs Supcrlatticc, SI Borcnstain, I Grave, A Larsson, D H Rich, BJonsson, I Andersson, J Westin and T G Andersson,Phys. Rev. M i (1991) 9320.

29. Observation of resonant Tunnelling in InSh/AIIrSbDouble-Barrier Structures, J R Söderström, J-Y Yaoand T G Andersson, Appl. Phys. Lett. 5S (1991) 708.

30. Temperature Dependent Critical Layer Thickness forIn 36Ga.64As/GaAs Single Quantum Wells, M JEkcnstedl, S M Wang and T G Andcrsscn, Appl. Phys.Lett. 5J£ (1991) 854.

31. Critical Thickness and Microstructurcs of StrainedInxGa,.xAs/GaAs QW's Studied by PL and TEM, T GAndersson, V D Kulakovskii, S Wang and J-Y Yao,SPIE Proc. 1261 (1991)?.

32. A Mechanical Probe for Accurate TemperatureMeasurements in Molecular Beam Epitaxy, M JEkenstcdt and T G Andersson, J Vac Sc Tcchnol Bj),(1991) 1605.

33. Effective Carrier Masses in a Neutral Quasi-two-Dimcnsional Electron-Hole Plasma in InGaAs/GaAsQuantum Wells with a Non-Degenerate Valence Band,JETPLctt.52 (1991)39.

34. Effect of the Nonparabolic Mass on the ElectronConfinement in Arbitrarily Shaped Quantum Wells,Wciquan Chen and T G Andersson, Phys Rev. B44(1991)9068.

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35. Many-Body Effects in Dense Electron-Hole Plasma inInGaAs QW's with Simple and Complex ValenceBand, LV Butov, V D Kulakovskii, T G Andersson, AForchel and D Griitzmacher, Surf. Sc. 262 (1991) 457.

36. Interface Morphology in Molecular Beam EpitaxyGrown In sGa 5As/GaAs Strained Heterostructures, SWang, T G Andersson and M J Ekcnstedt, Appl. Phys.Lett. 52 (1991) 2156.

37. Preparation of a Pt-GaAs Schottky Contact by IonPlating, G Petö and T G Andersson, Solid-StateElectronics M(1991)591.

38. Study of Modulation Spectrum of SemiconductorQuantum Wells. S. Qian, S. Yuan, J. Wu, Y. Li and T.G. Andersson, Chinese J. Scmicond. 12 (1991) 150.

39. Phoioluminesccncc Studies of InxGai.xAs/GaAsStrained Single Quantum Well Structures under HighPressure, G. H. Li, B. Z. Zheng, H. X. Han, Z. P.Wang, T. G. Andersson and Z-G Chen, Phys Rev. B45(1992-1)3489.

40. Molecular Beam Epitaxy Growth and Characterisationof InSb Layers on GaAs Substrates, J Söderström, MM dimming, J-Y Yao and T G Andersson, Scmic. Sc.Tcchnol.2(1992)337.

41. Quantum-Confined Stark Shift for Differently ShapedQuantum Wells, W Q Chen and T G Andersson,Semic. Sc. and Tcchnol. 7 (1992) 828.

42. Intcrsubband Transitions for Differently ShapedQuantum Wells Under an Applied Electric Field, W QChen and T G Andersson, Appl. Phys. Lett. öö (1992)1591.

43. Electron Mobility ant. Si-incorporation in InxGai.xAsLayers Grown on GaAs by Molecular beam Epitaxy,M J Ekcnstcdt, P Songpongs and T G Andersson,Appl. Phys Lett. £1 (1992) 789.

44. Direct Observation of Magneloplasmon-phononCoupled Modes in the MagnctophotoluminesccnceSpectra of the Two-dimensional Electron Gas inInxGai-xAs/GaAs Quantum Wells, LV Butov, VIGrincv, V D Kulakovskii and T G Andersson, PhysRev. Bi6_(1992-II) 13627.

45. InxGai.xSb/GaSb Quantum Well Structures Grown byMolecular Beam Epitaxy, M J Ekenstedt, E Olsson, GTreideris, T G Andersson, S M Wang and H Qu,Superi. Microstr. Microdevices, 12 (1992) 341.

46. Magnctoluminescence Study of Many-body Effects ina Dense Electron-hole Plasma of Strained InxGaj .xAs/GaAs Quantum Wells, LV Butov, V D Egorov, V DKulakovskii and T G Andersson, Phys Rev. B4&(1992-1) 15156.

47. Temperature Dependent Transition from two Dimen-sional to Three Dimensional Growth in HighlyStrained (0.36<x<l) Single Quantum Wells, S MWang, T G Andersson and M J Ekenstedt, Appl. PhysLett. 61(1992) 3139.

48. Determination of In Composition in Molecular BeamEpitaxy Grown InxGa|.xAs/GaAs Heterostructures, SM Wang, E Olsson, G Treidcris and T G Andersson, J.Cryst. Growth 122(1992)616.

Separate Conference Publications49. Intcrfacial Microstructure In InxGai.xAs/GaAs

Strained Layer Structures, J Y Yao, T G Anderssonand G L Dunlop, MRS Proc. 148 (1989) 303.

50. A Weak Beam Imaging Technique for the Characteri-sation oh Intcrfacial Roughness in Strained LayerStructures, J Y Yao, T G Andersson and G L Dunlop,MRS Proc. 159(1989).

51. InxGai.xAs/GaAs Critical Thickness Analysed by PLand TEM, T G Andersson, V D Kulakovskii, S Wangand J Y Yao, 20th Int. Conference on Physics ofSemiconductors, Aug. 6-10,Thcssaloniki, 1990.

52. Critical Thickness and Microstructurcs of StrainedInxGai.xAs/GaAs QW's Studied by PL and TEM, T GAndersson, V D Kulakovskii, S Wang and J-Y Yao,SPIE's Int. Conf. of Phys. Concepts of Mat. for NovelOptoelectronic Device Applications, Oct. 28- Nov. 2,Aachen, 1990.

53. Quantum Confined Stark Shift for Differently ShapedQuantum Wells, W Q Chen and T G Andersson, 6thInternational Conference on Solid Films and Surfaces,June 29-July 3,1992, Paris, France.


Liquid Crystals

Research SummaryThe activities of the liquid crystal group cover basicand applied research on thermotropic liquid crystals.The emphasis during the period reported has been onsmectic liquid crystals, with particular attention toferroelectric smectics. An extensive installation ofexperimental equipment for thermal, electrical andoptical investigations has been made. Since thegroup internationally is a pioneer in the field of chiralsmectic liquid crystals, the development of noveland often unique experimental techniques and meth-ods forms an important part of the activity. Equallyfundamental is theoretical progress, especially in theareas of phase transitions, continuum theory andferroelectricity, and in several cases basic experi-mental methods and theoretical concepts, now usedroutinely in many laboratories, have their origin inwork performed at Chalmers. The detailed physicalinvestigations of smectics rely on the possibility toobtain aligned samples of good quality. This moti-vated the installation of a clean-room facility withheavy equipment, e.g. a thin-film evaporator, andprocessing facilities.

The definite identification of smectic phases in anovel liquid crystal substance is a time-consumingbut very important work, as is the establishment ofphase diagrams and transition characteristics. Meth-ods used in our laboratory are optical microscopy oftextures, miscibility studies and thermal analysis(DSC).

Chiral tilted smectic phases are the first examplesof ferroelectric fluids, and it is of fundamental inter-est to study the nature of this type of ferroelectricityand its relation to symmetry and structural proper-ties. Typical experiments in this field are studies ofthe ferroelectric hysteresis, the molecular tilt angleand the helicoidal macro-structure. Collective mo-lecularexcitations, such as soft-mode and Goldstonemode in the C* -phase, are studied by dielectricspectroscopy. This technique also enables one todetermine important viscosity and elasticity param-eters. Ferroelectric liquid crystals have unique electro-

optic properties, and their exploitation in varioususeful devices strongly stimulates further researchon these materials.

Many chiral smectic substances exhibit aferroelectric-paraelectric transition at the tempera-ture of the tilted- non-tilted (e.g. C*-A*) transition.In the non-tilted phase, an external electric field willpartially induce an orientational order of the molecu-lar dipoles, and because of the chiral structuralsymmetry also induce a molecular tilt, i.e. transformthe non-tilted phase into a tilted one. Thiselectrocliniceffect has been studied both from a fundamental andan applied point, and its occurrence also in chiralnematics is under investigation. The over-all experi-mental situation in chiral smectic materials is veryrich and promising, as was also evidenced by theSecond International Ferroelectric Liquid CrystalConference (FLC 89), held in Göteborg June 26-301989 and arranged by the Chalmers group.

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31772 3379Fax+46 31 772 3436

StaffSenior MembersSven T. LagerwallBengt SteblerKent SkarpTomas CarlssonGunnar AnderssonIngolf Dahl

Fathi GoudaLachezar KomitovPeder Rodhe

professordocentdocentdocentfil.dr.fii.dr.(atHasselblad Opt.Imaging)fiLdr.Ph.D.Ph.D.(atFLCOptics/CIT)

164 THE CENTRE FOR

LIQUID CRYSTALS

Graduate StudentsAnders Dahlgren fil.lic.Marek Matuszczyk fil.lic.Thomasz Matuszczyk fil.lic.Marius Buivydas M.Sc.David Hermann fil.kand.Per Rudqvist civ.ing.

Techn.adm. personalHarriet Hast/Ingrid RiedlJohan Persson

secretary

Major Instrumentation• Differential Scanning Calorimeter, Perkin

Elmer DSC-7• Balzers Evaporator BAK-600• Zeiss Photomicroscope• Leitz Orthoplan polarizing microscope• HP 4192 Impedance Analyzer w. computer• Bruker Magnet• Clean room w. processing equipment• Malvem Correlator

(for light scattering studies)• Edwards evaporator 306A• Edwards RF-sputter ESM100• Mask- Aligner OAI800

Financial Support• The Swedish National Board for Technical

Development, NUTEK• Swedish Technical Research Council, TFR• The Swedish Natural Science Research

Council, NFR• The Swedish Work Environment Fund, AMF• The Bank of Sweden Tercentenary

Foundation, RJ• The Carl Trygger Scientific Research

Foundation

Major Reids of ResearchA: Physics of ferroelectric liquid crystals.

B: Electro-optics and applications of ferroelectricliquid crystals.

Research ProjectsA: Physics of ferroelectric liquid crystals

A l : Ferroelectric polarizationand viscosity

The most important and distinguishing property of aferroelectric material is the occurrence of spontane-ous polarization or macroscopic dipole moment.This basic parameter is closely linked to the symme-try propertiesof the ferroelectric crystal. Ferroelectricliquid crystals (FLC) are no exception from this rule,although the appearance of the polarization has somesurprising and distinguishing peculiarities. The po-larization vector is related to the smectic layer nor-mal and the local optical axis direction by a vectorialcross product. Consequently, in a study of FLC it isimportant to specify polarization as well as crystaldirections. This implies the need for techniques tomake samples of good alignment quality.

We have developed two experimental set ups fordetermination of spontaneous polarization wherethe ferroelectric contribution to the electrical con-ductivity can be separated and measured. The ex-periments are combined with optical polarizationmicroscopy which enables determination of the nec-essary crystal properties of the FLC. Also importantmolecular dynamic properties like the rotationalviscosity can be determined in these experiments.

The strange features with the liquid crystalferroelectricity are a result of symmetry and order.Thus only line defects are permitted in the 3Dmedium, which prohibits the formation of walls andthereby of polarized domains. Therefore, theGöteborg results from 1979-80 that the FLC materi-als can be polarized in thin samples by the action ofsurfaces - the so-called surface-stabilized ferroelectricliquid crystals (SSFLC) - was the turning point thatdeveloped this branch into the most active one inliquid crystals in the last decade. The seminal paperin Appl. Phys.Letters from 1980 is increasinglyreferred to (according to The Citation Index thispaper alone was referred to 45 times in 1987 and 102times in 1988). This Chalmers research has also beenthe basis for essentially all FLC applications so far,with &-, exception of the latest years when the firstapplications of the second basic breakthrough by ourgroup, the soft-mode effect (ef. A2) were announced.

A second strange feature is that the electrostaticinteraction between local dipoles is not responsiblefor the macroscopic polarization. This should be


LIQUID CRYSTALS

reflected in the order parameter, although no satisfy-ing proposal for such a parameter had been presentedso far. A considerable part of our activity has there-fore been directed to the ferroelectric order and to themolecular origins of ferroelectricity, which will bementioned further below under A3.

A2: The electro-clinic effectIn chiral orthogonal smectic phases (A*, B*, E*), theapplication of an electric field along the layersinduces a molecular tilt. This electroclinic effect hasbeen studied in the group extensively in later years,and it forms an extension of our work in chiralsmectics from the tilted ferroelectric phases (C*, I*,H*, G*) to the non-tilted paraelectric phases (A*,B*, E*), where the electroclinic effect is a soft-modeexcitation. The important features of the soft-modeeffect can be summarized briefly: the induced mo-lecular tilt 6 is a linear function of the field E, whereasthe response time is field-independent. Near thesecond-order transition to the ferroelectric phase, thesituation is more complicated, with a field-depend-ent response time and non-linear tilt-field character-istic.

A3: Basic theory for the smectic phasesThe order parameter concept, the Landau theory ofphase transitions, and the elasticity theory are basicelements in the theoretical description of the physicsof the smectic-A and -C phases. Ourresearch aims ata coherent, systematic description, fulfilling basicsymmetry principles, in a form that is comprehensi-ble and applicable to all possible geometries that canbe found experimentally. A systematic choice oforder parameters together with the correspondingLandau expansion has been presented. The elasticitytheory from the Orsay group (1971) was reformu-lated in a new systematic vector formulation in Dahland Lagerwall (1984), and further discussed in areview article by Lagerwall and Dahl (1984) Thiselasticity theory was further developed with theinclusion of the effects due to flexoelectric effectsand inhomogeneties in the electric field. The elastic-ity theory has also been extended to cover the case ofcompressible layers. This research project is alsocovered by the thesis of Dahl (1990). A slightlydifferentlineof theoretical research on chiral smecticsis the approach, based on the Landau theory of phasetransitions, taken first by a Russian group in the 70's,

and then further developed in a collaboration be-tween the Chalmers and Ljubljana groups. Fromthese Landau models of the smectic A*-C* phasetransition one can deduce the temperature depend-ence of the most important parameters, e.g. the tiltangle, the spontaneous polarization and the dielec-tric constant.

A4: Dielectric propertiesDielectric studies of liquid crystals provide valuableinformation of great interest both from fundamentaland applied aspects. Chiral smectic liquid crystalsexhibit a rich variety of fundamental dielectric phe-nomena, many of them of great application rel-evance and therefore most of our dielectric studiesare focussed on the chiral smectic A (A*) andsmectic C (C*) phases. Additionally we also havecarried out some measurement on non-chiral mate-rials. In dielectric studies one usually measure thereal e ' and imaginary e " parts of the complexdielectric permittivity e*. In our group this study iscarried out in the frequency regime 1 Hz - 13 MHzas a function of temperature. In order to resolve themain tenscrial components of e* (namely E|| and E_L),we carry out the measurements in two differentmeasuring geometries; homeotropic and planarorientations (to measure ey and ej_ respectively). Theformer orientation is achieved by surfactant, and thelater is obtained either by means of a magnetic fieldor by shear and small signal ac field.

» • ' 10' Kr1 I05 m1 Id" K>" I » "

Frequency / Hz

Dielectric relaxation modes in a ferroelectric liquidcrystal.

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In the A* phase there is an additional contribution toex due to distortion of the tilt angle, the so-called softmode. In the ferroelectric C* phase, in addition to thepermittivity characteristic of the non-chiral C phase,there are two contributions to e_|_. The first one is thesoft mode-as in the A* phase- and the second one dueto the helix distortion, the so-called Goldstone mode.In collaboration with the Ljubljana group (Yugosla-via), we have studied temperature and bias fielddependence of the dielectric permittivity and relaxa-tion frequency of the soft mode and Goldstone modewhich are the distinctive features of the dielectricproperties of the A* and C* phases. From ourinvestigation of the soft mode in the A* and C*phases we have offered a way to determine the A* -C* phase transition temperature to a good accuracy.

One of the main aims of this research is to utilizedielectricrelaxationmeasurementstodeterminesomeof the important material properties, e.g. viscoelasticcoefficients, tilt angle, and dielectric anisotropy. Inthe C* phase, when the helical structure is deformedand allowed to relax, it does so with a characteristicrelaxation time to the unperturbed state driven by anelastic torque and counteracted by a dissipativeviscous torque. The appropriate expressions havebeen derived and we have determined the involvedelastic constant and the rotational viscosity of theGoldstone mode. Based on dielectric absorptionmeasurements of the parallel component of e* in theA and C phases of chiral and non-chiral compounds,we have determined the tilt angle and its temperaturedependence in the C phase.

The major technical significance of dielectricstudies at present is the importance of the dielectricanisotropy (£|| - Ex) for device applications. We havestudied the frequency dependence of the dielectricanisotropy for different commercially availableferroelectric liquid crystal materials in the frequencyrange 103 - 1 0 6 Hz. Using these measurements wehave calculated the dielectric torque and compared itwith the ferroelectric torque. These results enabledus toconsider the torque balance asafunction of fieldand frequency, and thereby identify appropriatedriving conditions for FIX devices.

A5: PyroelectrlcityThe pyroelectric effect can be used to measure theelectric polarization in various polarized materials,and the method is suitable for measuring the sponta-

neous polarization in ferroelectrics. A chopped lightbeam generates a temperature ripple in the sample.Since the electric polarization is in general tempera-ture dependent, an electric current pulse responsecan be detected. This method has some advantagesover our standard methods, where the substance isreoriented by an electric field. In the pyroelectricmethod, the external electric field is not an integralpart of the measuring process, and effects of the fieldcan be sorted out. Since the sample is not reorientedthe method is suitable for high viscosity substances,like ferroelectric liquid crystalline polymers, whichare of future interest for us. From the electric fielddependence of the pyroelectric coefficient the ni-electric suspectibility is obtained. Elasticity and vis-cosity can be calculated from the pyroelectric coef-ficient and tilt angle and relaxation time data.Wewant to include pyroelectric studies in our arsenal ofexperimental techniques. Therefore, we have built asetup for basic pyroelectric measurements, to gainexperience in this technique. A diploma work on thepyroelectric effect has been completed.

A6 Calorimetry and phase identificationofsmecticLC's

Differential scanning calorimetry (DSC) measure-ments along with optical and electrical measure-ments are important tools in development and basicunderstanding of the nature of different phase tran-sitions in liquid crystalline materials. As there areabout 20different liquid crystalline phases identifiedto date in thermotropic systems alone, the situationis complex but rich, in particular in areas like com-mensurate - incommensurate transitions and theLandau theory of phase transitions.

The purpose of differential thermal systems is torecord the difference between the enthalpy changewhich occurs in a sample and an inert referencematerial. The sample and reference are providedwith individual heaters, making it possible to recordthe difference in power input to the two systemovens, giving a "null-balance principle" system. It isconvenient to think of the system as divided into twocontrol loops. One loop for average temperaturecontrol of sample and reference oven, so that it ispossible to increase or decrease the temperature at apredetermined rate, which then is recorded. Sec-ondly, the other loop ensures that if a temperaturedifference develops between sample and reference


LIQUID CRYSTALS

due to an exothermic or endothermic reaction in thesample (for instance a phase transition), the powerinput to the sample is adjusted to maintain constanttemperature at the sample and reference. The signalproportional to the difference in power input to thesample and to the reference, dH/dt, is then fed into acomputer. The recorded data are plotted in the formof a thermogram, from which several importantfeatures of the phase transitions can be evaluated.

B Electrooptlcs and applicationsof ferroelectric liquid crystals

B l : Applications of ferroelectricliquid crystals

The polar coupling of ferroelectric liquid crystals'(FLC's) large optical anisotropy to external electricfields is useful for light-modulating devices with thedesirable combination of fast, low-voltage, low-power switching properties. This combination ofproperties is not found in any other electrooptictechnologies, ensuring that FLC's will find aplace asthe light-controlling element in e.g. light-modula-tors, computer screens and optical processing de-vices. The rapid change of their polarization withtemperature near the phase transition makes themalso useful as thermoelectric detectors. The largeinternational effort over the past ten years to developpractical devices exploiting FLC's has required thedevelopment of a detailed understanding of thephysics of FLC devices and the techniques used tofabricate them.

B2: Electrooptic addressingCurrently available liquid crystal devices of thenematic type react with a quadratic response to thepresence of an electric field. When the field vanishesthe device returns to an OFF state by means of elasticforces only. This strongly limits the speed and achiev-able multiplexing rate.

Surface stabilized ferroelectric liquid crystals(SSFLC) possess a linear electro-optic effect whichmeans that they can be actively switched in bothdirection, i.e. symmetrically between the ON andOFF states. With the same low voltage and lowpower requirements as conventional liquid crystalsseveral ciders of magnitude faster. In addition,proper boundary conditions give the effect the valu-

able property of being bistable.The application areas of SSFLC's span from

simple light beam choppers through camera shut-ters, printer engines, wide viewing angle computer-and TV-screens to high speed optical processing,devices, such as real-time fourier transformers andcorrelators and optical computer elements for paral-lel numerical processing.

Suitable driving waveforms are different fromthe conventional ones and their design is based on thefollowing considerations:• the SSFLC cell can be switched between two

stable states by applying a polar voltage pulseof certain height and length;

• there exists a sharp switching threshold deter-mined by a critical pulse integral;

• in order to prevent electrochemical degradationa DC content in driving waveforms should beavoided at the same time as DC pulses have tobe used in every individual switching opera-tion..

A liquid crystal display consists of a pair of glassplates with a set of transparent electrodes sputteredon each of them. Then an additional black mask andaligning layers are evaporated, the glasses fitted ontop of each other with a distance of l-2fjm, where-after they areglued and the cell filled with aferroelectric liquid crystal mixture. The electrodesusually form a matrix. Elements of such a matrix (socalled pixels) can be switched by scanning one set ofelectrodes (rows) while applying proper data-wave-forms to the second one (columns). Due tobistabilityof SSFLC devices such scanning can be performedcontinuously, periodically (frame updating - whendesired) or selectively (row or pixel updating). Dur-ing a scan, voltage pulses of desired polarity and areaare sequentially applied to selected pixels. Non-selected pixels should then experience signals wellbelow threshold (or frequency high enough to let thedielectric torques dominate - so called ACstabilization).

Theoretical and experimental work has been donein our group in order to achieve high optical contrastand addressing speed suitable for applications andfulfill the above mentioned requirements.

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Conference arranged by thegroupSecond International Symposium on FerroelectricLiquid Crystals, Göteborg,Sweden, June 89 (200 overseas participants).

Publications

Ph.D. DissertationsChrister Alstermark, Liquid Crystals - Molecular Structure

and Macroscopic Properties; (1989)Ingolf Dahl, On Order, Fcrroclectricity and Elasticity in

Smectic Liquid Crystals, (1990)Gunnar Andersson, Electro-Optic Effects in Chiral Smectic

Liquid Crystals, (1992)Falhi Gouda, Dielectric Relaxation Spectroscopy of Chiral

Smectic Liquid Crystals, (1992)

Licentiate DissertationsChrister Alstermark, Synthesis of Chiral Smectic Liquid

Crystalline Esters, (1986)Tomasz Matuszczyk, Electronic Addressing of

Ferroelectric Liquid Crystals, (1991)Anders Dahlgren, Optical Properties and Helicity in Liquid

Crystals, (1991)Marek Matuszczyk, Development of Fast-Switching Chiral

Smcctic Electro-Optic Devices

Diploma WorkAnnika Lundström, Johan Nilsson, Methods for making

SSFLC-Cells for Optical Processors, (1986)Håkan Stennert, Dielectric and Electro-Optic Investigations

of Ferroelectric Liquid Crystals, (1989)Eric Toussaere, Pyroelectric Effect in Ferroelectric Liquid

Crystals, (1989)Peter Richnau, The Interface Between a Personal Compu-

ter and an LCD, (1989)Magnus Wijk, Pyroelectric Effect in Polymeric

Ferroelectric Liquid Crystals, (1991)Otto Gcrhäuser, A Joint Transform CorrelatorPer Rudquist, The Linear Electro-Optic Effect in a Chiral

Ncmatic Liquid CrystalAlain Gauge, Benoit Sabatier, Eric Pierre, Waveform

generator

Reports and articles1. Dielectric Relaxation and the Determination of the

SmA - SmC* Phase Transition Temperature inDOBAMBC, A.Levstik, T.Carlsson, C.Filipic andB.Zeks, Mol. Cryst. Liq.Cryst. 154,259 (1988)

2. Experimental Driver and Addressing Techniques forFerroelectric Liquid Crystal Devices, J.Wahl andT.Matuszczyk, J. Phys. E: Sci. Instr. 21,460 (1988)

3. Macroscopic Description of Ferroelectric ChiralSmectic C* Liquid Crystals, BZcks, T.Carlsson,C.Filipic and A.Levstik, Proceedings of the NATOadvanced research workshop: IncommensurateCrystals, Liquid Crystals, and Quasi-Crystals, Ed. J.F.Scott and N.A.Clark, NATO ASI Scries B: PhysicsVol 166(1988)

4. Ferroelectric Liquid Crystals. Materials Properties andApplications, K.Skarp and M.A.Handschy,Mol.CrysLLiq.Cryst., 165,439 (1988)

5. Thermodynamic Model of Ferroelectric LiquidCrystals and Its Microscopic Basis, B2eks,T.Carlsson, CFilipic and B.Urbanc, i toceedings of the1st Int-Symp. on Ferroelectric Liquid Crystals,Ferroelectrics 84,3 (1988)

6. The Soft-Mode Ferroelectric Effect, CAndersson,I.Dahl, W.Kuczynski, S.T.Lagerwall, K.Skarp andB.Steblcr, Proceedings of the 1st Int.Symp. onFerroelectric Liquid Crystals, Fcrroelcctrics 84,285(1988)

7. A 1 "x 0.5" FLC Bar-Graph Display with Short-TermMemory, K.Skarp, M.Matuszczyk, T.Matuszczyk,B.BijIcnga, Å.Hömell, B.Stcblcr and S.T.LagcrwaII,Proceedings of the 1 st IntSymp. on FerroelectricLiquid Crystals, Ferroelectrics 85,313 (1988)

8 Measurements of Rotational Viscosity in FourFerroelectric (C*), Liquid Crystals, K.Skarp,KPlaiischler and S.T.Lagerwall, Proceedings of the 1stInt.Symp. on Ferroelectric Liquid Crystals,Fcrroclcctrics, 84,183 (1988)

9. Rotational Viscosities in Ferroelectric Smcctic LiquidCrystals, K.Skarp, Proceedings of the 1 st Int.Symp. onFerroelectric Liquid Crystals, Fcrroclectrics, 84,119(1988)

10. Parameter Characteristics of a Ferroelectric LiquidCrystal with Polarization sign Reversal, R.Eidcnschink,T.Geelhaar, G.Andcrsson, A.Dahlgrcn.K.Flatischler,F.Gouda, S.Tlagcrwall and K.Skarp, Proceedings ofthe 1st Int. Symp. on Ferroelectric Liquid Crystals,Ferroclectrics, 84,167 (1988)

11. Interaction Between FLC:s and Electric Fields:Flcxoclectric Effects and Surfaces, I.Dahl, Proceedingsof the 1 st Int. Symp. on Ferroelectric Liquid Crystals,Fcrroelectrics, 84,345 (1988)

12. Different Types of Bistability in Ferroelectric LiquidCrystals, I.Dahl, Proceedings of the 1st Int. Symp. onFerroelectric Liquid Crystals, Fcrroclcctrics, 85,495(1988)


LIQUID CRYSTALS

13. Temperature and Wave Vector Dependence of theEigenfrequencies of the Goldstonc Mode and the SoftMode of Ferroelectric SmC* Liquid Crystals,T.Carlsson, B-Zeks, C.RIipic and A.Lcvstik, Proceed-ings of the 1st Int Symp. on Ferroelectric LiquidCrystals, Ferroelectrics, 84,223(1988)

14. Interaction Between Electric Field and Liquid Crystalswith Spontaneous Polarization: Derivation of SuitableFree Energy Expression For a Cell with an AppliedVoltage, I.Dahl, Proceedings of the 1st Int.Symp. onFerroelectric Liquid Crystals, Ferroelectrics, 84,327(1988)

15. Comments on Liquid Crystal Terminology, Nomencla-ture and Conventions, S.T.Lagerwall, Proceedings ofthe 1st Inl Symp. on Ferroelectric Liquid Crystals,Fcroelectrics, 85,497 (1988)

16 Dielectric Properties near the Smcctic C* - Smectic A*Phase Transition of some Ferroelectric Liquid Crystal-line Systems with a very large Spontaneous Polariza-tion, CFilipic, T.Carlsson, A.Lcvstik, B.Zcks, R.BIinc,F.Gouda, S.Tlagerwall and K.Skarp, Phys.Rev. A38,5833(1988)

17. Ferroelectric Liquid Crystals: the Key to LowradiatingVDUs, B.Olterholm, Kemisk Tidskrift No 10 (1988)(in Swedish)

18 Thcrmodynamic Model of Ferroelectric Chiral SmccticC* Liquid Crystals, T.Carlsson, BZcks, CFilipic,AlevstikandR.Blinc.Mol.Cryst.Liq.Cryst., 163,11(1988)

19 Stability of the Shear Flow of Ncmatic Liquid Crystalswith a Positive Leslie Viscosity a3, C.Högfors andT.Carlsson, Institute of Theoretical Physics, InstituteReport 89-3 (1989)

20. Precision Electric Bridge and Fast Electro-OpticDetector System for Studies of Ferroelectric Polariza-tion and Optical Switching in Ferroelectric SmecticLiquid Crystals, G.Andersson and K.Skarp, GöteborgInstitute of Physics Reports, GIPR - 273

21. Behaviour of the Soft Mode in the Smectic A* and C*Phases Studied by Dielectric Measurements, F.Gouda,G .Andersson, T.Carlsson, S.T.Lagerv all, K.Skarp,B.Stebler, C.Filipic, B.Zeks and A.Levstik,Mol.Cryst.Liq.Cryst.Leu., 6,151 (1989)

22. Dielectric Relaxation of a Mixture of a Ncmatic LiquidCrystal and a Non-Liquid Crystalline Compound,H.Kresse, H.Steuin, F.Gouda and G.Andersson,Phys.Stat.Sol. (a) 111, K265 (1989)

23 Introduction to Ferroelectric Liquid Crystals, ST.Lagerwall and N.A.Clark in "Ferroelectric LiquidCrystals", ed. G.W.Taylor, Gordon and Breach, NewYork, 1989

24. Experimental and Theoretical Study of the Influence ofa Bias Electric Field on the Dielectric Properties of theChiral Smectic A* Phase, F.Gouda, G.Andersson,S.T.Lagerwall, K.Skarp, B.Stebler, T.Carlsson, BZcks,CFilipic and A.Levstik, Liq.Cryst., 6,219 (1989)

25. Viscoelastic Properties of the Smcctic A* and C*Phases studied by a new Dielectric Method, F.Gouda,K.Skarp, G.Andersson, H.Kresse and S.T.Lagerwall,JpnJ.Appl.Phys., 28,1987 (1989)

26. Device Physics of the Soft-Mode Electro-Optic Effect,G .Andersson, I.Dahl, L.Komitov, S.T.Lagerwall,K.Skarp and B.Stcbler, J. Appl.Phys., 66,4983 (1989)

27. Ferroelectric Liquid Crystals: The Development ofDevices, S.T.Lagerwall, N.A.Clark, J.Dijon andJ.F.CJerc, Fcrroelectrics 94,3 (1989)

28. Put the TV on the Wall - the Flat Screen is under Way,B.Stebler, S.Berg, Electronics (Industry & Develop-ment), 1989

29. Liquid Crystal Devices Using a Linear Electro-OpticEffect, CAndcrsson, LDahl, L.Komitov,S.T.Lagerwall, K.Skarp and B.Stcblcr, EuropeanPatent application 8900563-i Submitted February 1989

30. Liquid Crystals - Molecular Structure and MacroscopicProperties, C.AIsiermark, Ph.D. Thesis, ChalmersUniversity of Technology (1989)

31. Theory of Ferroelectric Liquid Crystals, B.Zcks,C.Filipic and T.Carlsson, Physica Scripia, T25,362(1989)

32. The Concept of Rotational Viscosities of Smectic Cand Chiral Smcctic CLiquid Crystals, T.Carlsson andB.Zeks, Liq.Cryst., 5,359 (1989)

33. Determination of the SmA - SmC* Phase Transition inDOBAMBC and its Dielectric Relaxation, A.Lcvstik,T.Carlsson, C.Filipic and BZcks, FIZIKA 22, Suppl.2,181 (1990)

34. Theoretical Model of (he Frequency and TemperatureDependence of the Dielectric Constant of FerroelectricLiquid Crystals Near the Smcctic C* - Smcctic APhase Transition, T.Carlsson, B.Zcks, C.Filipic andA.Levslik, Phys.Rev. A42,877 (1990)

35. A Dielectric Method for Determining the RotationalViscosity in Thick Samples of Ferroelectric ChiralSmeclic C* Liquid Crystals, A.Lcvsuk, Z.Kutnjak,C.Filipic, I.Lcvstik, Z.Bregar, BZcks and T.Carlsson,Phys.Rev. A42,2204 (1990)

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36. Dielectric Anisotropy and Dielectric Torque inFerroelectric Liquid Crystals and their Importance forElectro-Optic Device Performance, F.Gouda,CAndcrsson, M.Matuszczyk, T.Matuszczyk, K.Skarpand S.TLagerwall, J.Appl.Phys. 67,180 (1990)

37. On Order, Ferroelectricity, and Elasticity in SmccticLiquid Crystals, I.Dahl, Ph.D. Thesis, University ofGöteborg (1990)

38 The Order Parameter and the Landau Expansion in theChiral Smcctic C Phase, 'I.Dahl and S.T.Lagerwall,Ferroelectrics 113,77(1991)

39. The Elasticity Theory of the Smcctic C Phase: Discus-sion about Different Approaches, I.Dahl, Fcrroclccuics113,103(1991)

40. The Elasticity Theory of the Smcctic C Phase: TheCase of Compressible Smcctic Layers, I.Dahl,Fcrroclcctrics 113,121(1991)

41. Dielectrics Studies of the Soft Mode and GoldsioncMode in Ferroelectric Liquid Crystals. F.Gouda,K.Skarp and S.T.Lagerwall, Fcrroclcctrics 113,165(1991)

42. Electrically Controlled Optical Attenuators andSwitches with Ferroelectric Liquid Crystals,A.Karppincn, S.Lottholz and K.Myllylä, G.Andcrsson,M.Matuszczyk, K.Skarp, I.Dahl and S.T.Lagcrwall,Fcmelectricsl 14,93 0991)

43. Smcctic A* Materials with 11.25 Degrees Induced TiltAngle for Full Grey Scale Generation, G.Andersson,I.Dahl, L.Komitov, M.Matuszczyk, S.T.Lagcrwall,K.Skarp, B.Steblcr.D.Coates, M.Chambers andD.M.Walba. Fcrroclcctrics 114,137 (1991)

44. Linear Elcctrooptic Effects in the Chiral NematicPhase, L.Komitov, S.T.Lagerwall, B.Slcbbr,G.Andcrsson and K.FIatischlcr, Fcrroclcctrics 114,167(1991)

45. Till Angle Determinations in Chiral and NonchiralSmcctic C Phases using Dielectric AbsorptionSpcctroscopy, F.Gouda, K.Skarp, S.T.Lagcrwall,C.Eschcr and H.Krcssc, Journal dc Physique 1,1,167(1991)

46. A Dielectric Method for Determining the RotationalViscosity in Ferroelectric Liquid Crystals, A.Levstik,Z.Kutnjak, C.Filipic, I.Lcvstik, B.Zeks and T.Carlsson,Fcrroclcctrics'13,207(1991)

47. Nonlinear Effects in the Dielectric Response ofFerroelectric Liquid Crystals, B.Urbane, B.Zcks andT.Carlsson, Ferroelcctrics 113,219 (1991)

48 Evolution of the Boulder Model for the MolecularOrigins of the Polarization in Ferroelectric LiquidCrystals, D.M.Walba, H.A.Ra/avi, A.Horiuchi,K.F.Eidmar., D.Gitcrholm, R.C.Haltiwangcr,N.A.Clark, R.Shao, D.S.Parmar, M.D.Wand andR.T.Vohra, Fcrroelectrics 113,21 (1991)

49. Smcctic Layer Switching Using a Field-Induced N*-C* Phase Transition, G.Andersson, K.FIatischler,L.Komitov, S.T.Lagcrwall, K.Skarp and B.Slcblcr,Fcrroclcctrics 113,361 (1991)

50 Sign Reversal of the Elcctroclinic Coefficient in theSmcctic B* Phase, L.Komitov, K.FIalischlcr,G.Andcrsson, S.T.Lagcrwall, B.Stcblcr, B.Oltcrholm,T.Olsson and C.Alstcrmark, Fcrroclcctrics i 14,151(1991)

51. Ncmatic Liquid Crystal Device, G.Andcrsson,L.Komilov, S.T.Lagcrwall, B.Stcblcr and K.Flatischlcr,Patent Application PCT/SE90/00101

52. Elcctroclinic Light Switch, A.Dahlgrcn, G.Andcrsson,L.Komitov, S.T.Lagerwall and B.Slcblcr, Mol. C'ryst.Liq. Cryst. 207,281 (1991)

53. Static Splay-Stripes in a Hybrid Aligned NcmaticLayer, A.Sparavigna, L.Komitov, B.Stcblcr andA.Slrigazzi, Mol. Cryst. Liq. Cryst. 207,265 (1991)

54. Surface Induced Alignment Transition in a NcmaticLayer with Symmetrical Boundary Conditions,K.Flatischlcr, L.Komitov, S.T.Lagcrwall, B.Stcblcr andA.Strigazzi, Mol .Cryst. Liq. Cryst. 198,119 (1991)

1>5 Theoretical Studies of Smcclic C Liquid CrystalsConfined in a Wedge - Stability Considerations andFredcriks Transitions, T.Carlsson, I.W.Stewart andF.M.Lcslic, Liq.Cryst., 9,661 (1991)

56. Hybrid Aligned Ncmatics and Second Order Elarr;:i:/,A.Sparavigna, L.Komitov and A.Strigazzi, PhysicaScripta43.210 (1991)

57. Electronic Addressing of Ferroelectric Liquid Crystals,T.Matuszczyk, Tckn. lie. Thesis, Chalmers Universityof Technology (1991)

58 Optical Properties and Hclicity in Liquid Crystals,A.Dahlgren, Tckn. lie. Thesis, Chalmers University ofTechnology (1991)

59. Anomalous Current and Elcctrooptic Response in aPolyacrylate Ferroclcctri»; Liquid Crystal with LargeSpontaneous Polarization, K.Skarp, G.Andcrsson,S.T.Lagcrwall, H.Kapit/a, H.Pots and R.Zcntcl,Fcrroclctlrics 122,127(1991)


LIQUID CRYSTALS

60. Influence of Twist Distortion on the Transition PointBetween Two Ncmatic Subphascs Nl and N2 ofHOBA, G.Barbcro, L.Komilov, M.Petrov andA.Strigazzi, Intl. J.Mod.Phys.BS, 2229 (1991)

61. Behaviour of Biaxial Ncmatics in the Presence ofElectric and Magnetic Fields-Evidence of Bistability,T.Carlsson and F.M.Lcslie, Liq.Cryst., 10,325 (1991)

62. Equivalent Formulations of Smectic C Elastic Ener-gies, I.W.Stcwart, T.Carlsson, F.M.Lcslie andM.Nakagawa, J.Cont.Mcch.Thcrmodyn., 3,237 (1991)

63. Elcctroclinic Effect in Some Side-Chain PolysiloxaneLiquid Crystals, KPlatischler, L.Komitov, K.Skarpand P.Kellcr, Mol.Cryst.Liq.Cryst. 209,109 (1991)

64. Flow Properties of Biaxial Ncmatic Liquid Crystals,T.Carlsson, F.M.Leslie and J.S.Lavcrty,Moi.CrystXiq.Cryst. 210,95 (1992)

65. Biaxial Ncmatic Liquid Crystals - Flow Properties andEvidence of Bistability in the Presence of Electric andMagnetic Fields, T.Carlsson, F.M.Leslic andJ.S.Laverty, Mol.Cryst.Liq.Cryst., 212,189 (1992)

66. Formation of Walls in Cylindrical Smectic C Layers inthe Presence of a Tilted Magnetic Field, T.Carlsson,I.W.Stcwart and F.M.Leslic, Liq.Cryst. 11,49( 1992)

67. An Elastic Energy for the Ferroelectric Chiral SmecticC Phase, T.Carlsson, I.W.Stcwart and F.M.Leslic,J.Phys.A. 25,2371 (1992)

68. Soft Mode Dielectric Anomaly of the Chiral Smcctic BPhase with Sign Reversal Elcctroclinic Response,F.Gouda, T.Carlsson, K.Flatischlcr, L.Komitov,S.T.Lagcrwall, K.Skarp and B.Stcbler, Phys.Rcv.A 45,5362(1992)

69. Electrically Induced Mechanical Vibrations of aSurface Stabilized Ferroelectric Liquid Crystal Cell,N.Ebcr, L.Komitov, S.T.Lagcrwall, M.Matuszczyk,K.Skarp and B.Stcbler, Fcrroclcctrics 129,19 (1992)

70. Influence of a Magnetic Field on the Peru* ;Splay-Stripcs in Hybrid Aligned Ncmatics, A.Sparavigna,L.Komilov and A.Strigazzi, Mol.Cryst.Liq.Cryst. 212,289(1992)

71. S ign Reversal of the Spontaneous Polarization in theC* Phase of a Side-Chain Polyacrylatc and itsMonomer, G.Schcrowsky, B.Braucr, K.Griincbcrg,U.MUllcr, L.Komitov, S.T.Lagcrwall, K.Skarp andB.Stcblcr, Mol.Cryst.Liq.Cryst. 215,257 (1992)

72. Investigations of Soft-Mode and Elcctroclinic Re-sponse in a Ferroelectric Liquid Crystal withDs =5mC/m2, K.Skarp, G.Andcrsson, T.Hirai,A.Yoshizawa, K.Hiraoka, H.Takc/.oc and A.Fukuda,Jpn.J.Appl.Phys. 31,1409(1992)

73. Dielectric Relaxation Spectroscopy of Chiral SmccticLiquid Crystals, F.Gouda, Ph.D.Thcsis, ChalmersUniversity of Technology (1992)

74. Electro-Optic Effects in Chiral Smcctic Liquid Crys-tals, G.Andcrsson, Ph.D.Thcsis, Chalmers Universityof Technology (1992)

75. Determination of the Dielectric Biaxiality in a ChiralSmectic-C Phase, F.Gouda, W.Kuczynski,S.T.Lagerwall, M.Matuszczyk, T.Matuszczyk andK.SHrp,Phys.Rev.A46,951 (1992)

76. Fluorescent Liquid Crystal Polymers ExhibitingFerroelectric and Electroclinic Switching,G.Scherowsky, A.Bccr, L.Komitov and S.T.Lagerwall,Proc. 21st Freiburg Workshop on Liquid Crystals(1992)

77. Anufcrroclcclnc Behaviour in a Liquid CrystallinePolymer, K.Skarp, G.Andcrsson, F.Gouda,S.T.Lagerwall, H.Pots and R.Zcnicl, Polymers forAdvanced Technologies 3,241 (1992)

78. Fast Elcctroclinic switching in a Ferroelectric LC-Polysiloxane H.Poths, G.Andcrsson, K.Skarp andR.Zcntcl, Adv. Mater 4,792 (1992)

79. Surface Transition in a Ncniaic Layer with ReversePrctilt, L.Komitov, S.T.Lagcrwall, A.Sparavigna,B.Stcblcr and A.Strigazzi, Mol.Cryst.Liq.Cryst. 223,197(1992)

80. A Macroscopic Theory for the Row Behaviour ofSmcctic C and Smcctic C* Liquid Crystals,T.Carlsson, F.M.Leslic and N.A.Clark, Phys.Rcv. A,submitted for publication

81 Continuum Theory for Biaxial Ncmatic LiquidCrystals, F.M.Leslic, J.S.Lavcrty and T.Carlsson,QuarU.Mech.Appl.Math (in press)

82. Broad Band Dielectric Relaxation Spectroscopy of aChiral Smcctic B - Crystal Phase F.Gouda, K.Skarp,S.T.Lagcrwall, B.S'-.1 Icr, F.Krcmcrand S.U.Vallcricn,Phys.Rcv.A, accepted for publication

83. Theoretical Studies of the Influence of Backflow on theDynamical Behaviour of a Fredericks Transition of aFerroelectric Smcctic C* Liquid Crystal in the Book-shelf Geometry, T.Carlsson, N.A.Clark and Z.Zou,Liq.Cryst., submitted for publication

84. Manifestation of the Biquadratic Coupling in (heSmcctlc C* Phase from the Soft Mode DielectricResponse, F.Gouda, T.Carlsson, G.Andcrsson,S.T.Lagcrwall and B.Slcblcr, Phys.Rcv.A., submittedfor publication

172 THE CENTRE FOR

Superconductorsand nanometerstructuresApplied Solid State Physics 174Condensed Matter Theory 196See also under Materials Physics


Applied Solid State Physics

Research SummaryThis is a rather large research group fluctuatingbetween 25 and 37 persons depending upon thenumber of guest researchers, vacations, etc. Theresearch is focussed onto tunneling, superconductiv-ity and very small structures made in a controlledway. The research encompasses sample preparation,like epitaxially grown films or amorphous alloys,and their characterization (using structural,microstructural, compositional, electrical transportand tunneling methods) and processing (patterning,plasma etching, oxidation, etc) into structures thatare investigated. Components are developed andinvestigated. In particular, we specialize in studies ofnew quantum effects and investigate theirfeasibilityin possible detectors or sensors operating at thequantum limit. The group operates the nationalnanometer facility that is used by several groups atChalmers and by other groups in Sweden, Europeand America. The activity contains mainly basic butalso applied research within both science and tech-nology. A large network of world wide cooperationhas been built up. We investigate materials frominsulators to superconductors, fabricate structuresdown to 20 nm (or even smaller by STM), usetemperatures from 300 K to 0.005 K, and performvery sensitivemeasurements from sub-Hz (1/f noise)to THz frequencies.

Epitaxial films of high temperature superconduc-tors are deposited by several methods. The filmnucleation and growth is studied by a number ofmethods, likeelectron microscopy, atomic force andscanning tunneling microscopy, and electrical trans-port. Multilayers, in particular superconducting lay-ers separated by insulators are needed for manyapplications and a large effort is devoted to theepitaxial growth of such layers. The layers have to befree from particles, large inclusions or other defects.Crossings of lines, needed in, for example, couplingtransformers, and interconnects, are large problems,and basic materials research is needed. The films areprocessed to Josephson junctions, using bi-crysta!based grain boundaries, bi-epitaxial growth on tem-

plates, shallow or deep steps etched into substrates,nanobridges and so on. The nature of these weaklinks is not fully understood. The junctions areutilized in a number of feasibility studies: Supercon-ducting Quantum Interference Devices as sensor ofextremely small changes in magnetic fluxes; fluxflow oscillators, coupled Josephson oscillators, am-plifiers, and mixers for very high frequencies; hotelectron devices; and digital circuits based on singleflux quantum transport or flux flow transistors.Novel three-terminal devices are also invented.

Work is also continuing on conventional super-conductors at high frequency.

A speciality of the group is single charge tunneling.Charges (single electrons or Cooper pairs in a super-conductor)can tunnel coherently one byonein ultra-small tunnel junctions. The periodic motion can bephase locked to an external microwave signal givingrise to voltage steps at currents I=nef. Including aJosephson coupling, it is possible to obtain Blochoscillations. The transition region between singleelectron and single pair tunneling is of great interest.It is also possible to control the tunneling of singleelectrons by shifts much less than a single chargequantum of the charge distribution on a small elec-trode between two junctions. Our feasibility studiesgive electrometers with a sensitivity of 0.0001 e/VHzand single electron transistors with high power gain.2D arrays and transitions between Josephson andCoulomb blockade dominated regions are also stud-ied.

Another topic is the development of new scan-ning microscope probes and their utilization in study-ing surfaces with atomic resolution.

AddressDepartment of PhysicsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 772 3303Fax+46 31 16 5176

!74 THh CENTRE FOR

APPLIED SOLID STATE PHYSICS

StaffSenior Members:Tord ClaesonPer DelsingDavid HavilandZdravko IvanovHåkan OlinHåkan OlssonDag Winkler

professortekn.dr.Ph.D.Ph.D.tekn.dr.tekn.dr.tekn.dr.

Long Term Visiting Scientists:Yuri BoikovDonats ErtsYuichi HaradaVsevolod KaplunenkoSergei KubatkinLeonid KuzminVictor PetrashovEvgeni StepantsovAlexandre TzlentchoukErland WikborgStefan Zarembinski

Graduate StudentsVladimir AntonovGöran BrorssonMartin DanerudChen ChiiDongPer DavidssonJonas EdstamRafi GattNiklas MrosPer-Åke NilssonYuri PashkinMagnus PerssonJoakim PetterssonJaime RamosHuai-ren YiZhang Yongming

Technical StaffAlexei BogdanovOve ErikssonZdravko IvanovPeter LarssonBengt NilssonStaffan Pehrson

SecretaryAnn-Marie Frykestig

Ph.D.Ph.D.Ph.D.Ph.D.Ph.D.Prof.Prof.Ph.D.

: Ph.D.doc.Ph.D.

M.Sc.civ.ing.tekn.lic.M.Sc.tekn.lic.tekn.lic.M.Sc.civ.ing.tekn.lic.M.Sc.tekn.lic.tekn.lic.M.Sc.M.Sc.tekn.lic.

Ph.D.ing.Ph.D.civ.ing.civ.ing.ing.

CollaboratorsVladimir Antonov, Inst of Microel Technology,

Chemogolovka, RussiaYuri Boikov, Ioffe Institute, St Petersburg, RussiaJim Boyce, Xerox, Palo Alto, USAFrank Bridges, UCSC, USALie Chen, Academy of Sciences, Beijing, ChinaDonats Erts, University of Latvia, LatviaTed Geballe, Standford University, USAEvgeni Gershenzon, Moscow State Pedagogical

Inst, RussiaGregory Goltsman, Moscow State Pedagogical

Inst, RussiaYuichi Harada, Tokyo Institute of Technology,

JapanSergei Kubatkin, P Kapitza Inst for Physical

Problems, Moscow, RussiaVsevolod Kaplunenko, Inst of Radio Eng and

Electronics, Moscow, RussiaBoris Karasik, Moscow State Pedagogidal Inst,

RussiaLeonid Kuzmin, Moscow State University, RussiaGennadi Ovsyannikov, Inst of Radio Eng and

Electronics, Moscow, RussiaYuri Pashkin, Moscow State University, RussiaVictor Petrashov, Academy of Sciences,

Chernogolovka, RussiaAndy Poliakov, MoscowEvgeni Stepantsov, Academy of Sciences, Mos-

cow, RussiaAlexandra Tzlentchouk, Academy of Sciences,

Moscow, RussiaShouzheng Wang, Peking University, ChinaStefan Zarembinski. PAN, Warsaw, PolandMichael Zorin, Moscow State Pedagogical Inst,

RussiaCollaboration within ESPRIT program with Univ.

Tubingen, Glasgow, Salerno, DTH, CNRSGrenoble

Collaboration within ESA program with DTH,Univ. Twente, NKT, Univ. Copenhagen

Collaboration within NORPAS program withEricsson, ABB, NKT, DTH, LiTH.

Major Instrumentation• Nanometer laboratory• 9 deposition units• Cryogenic laboratory, 300 - 0.006 K.



Rf, microwave and mm wave measurementsSensitive measurements in shielded roomSTM, AFM, and other scanning probes

Major Fields of ResearchA. Superconducting Microelectronicsparticipants: G. Brorsson, T. Claeson, M.

Danerud, Z.G. Ivanov, P. Larsson, P.Å.Nilsson, J. Ramos

collaborators: J. Alarco, A. Andersson-Fäldt, C.G.Granqvist, E. Olsson, (Phys. Dept.), G.L.Johansson, (Chem. Dept.), M. Löfgren, (Appl.El. Phys.), ö. Rapp, (Royal Inst. of Techn.,Stockholm), V. Kaplunenko, G. Ovsyannikovand M. Tarasov (Inst. Radio Eng. and Elect.,Moscow), E. Wikborg (Ericsson, Stockholm),Yu. Boikov (Ioffe Inst., St. Petersburg), E.A.Stepantsov, A.Ya. Tzalenchuk (Inst. Cryst.,Moscow), S. Dubonos (lost. Microel. Techn.,Chernogolovka), T. Freltoft (NKT, Denmark),A. Samoilov (Kapitza Inst., Moscow).

B. Nanofabricatlon and Nanotechnologyparticipants: Alexei Bogdanov, B. Nilsson,,

Andrei Poliakovcollaborators: This is a national facility which is

utilized by a large number of researcher withinand outside the university.

C. Mesoscoplc Physicsparticipants: P. Delsing, D. Haviland, Y. Harada,

L. Kuzmin, M. Persson, J. Pettersson, ChenChiidong

collaborators: V. Antonov, Y. Pashkine and V.Petrashov

D. Scanning Tunneling Microscopyparticipants: H. Olin, P. Davidssoncollaborators: B.O. Aronsson, IT. Engström, J.

Gold, C-G. Granqvist, B. Kasemo, J. Lausmaa,G. Mbise, G. Niklasson, H. Norden, E. Olsson,M. Rodahl, A. Rosén, K. Skarp (Phys. Dept.),L. G. Johansson (Chem. Dept.), T. Hjertberg(Polymer Techn.), H. Bertilsson (PolymericMaterials), G. Stemme (Computer Eng.), D.Erts (Univ. Latvia), M. Stenberg (Inst Histol-ogy), S.E. Kubatkin (Kapitza Inst., Moscow).

Research Projects

A: Superconducting Microelectronics

A l : Films of High Tc SuperconductorsThe aim of the project is to study the mechanism ofepitaxial growth and properties of high-Tc thin films:YBaCuO, BiSrCaCuO and TIBaCaCuO. Differentdeposition methods, as co-evaporation, magnetronsputtering and pulsed laser deposition are involved,but the main effort is in the pulsed laser deposition.Epitaxial thin films have been grown on a variety ofsubstrates, including single crystal and amorphousones, with state-of-the-art results. Films are charac-terized by transport measurements and microstruc-ture analysis. A natural prolongation of the activityis to study film growth of high-Tc films on semicon-ductor substrates, Si and GaAs, with buffer layers.

A2: Multilayers of High Tc Superconductors/Insulators

Multilayer structures of high-Tc materials are thecorner stone in the development of high-Tc super-conducting integrated circuits. This project aims atdeveloping a basic understanding of growth mecha-nisms of multilayer structures based on high-Tc

superconductors, insulators, semiconductors andnormal metals. Multilayers YBCO/NdGaOj andYBCO/SrTiO3/PrGaO3 have been grown and stud-ied. 'Hie growth conditions are correlated with mi-crowave and transport properties of superconduc-tors and their microstructure. This study is requiredfor the future development of high-Tc devices: mi-crowave passive circuits and integrated digital cir-cuits.

A3: Patterning of SuperconductorsThe project is connected with development ofnondestructive patterning of high-Tc thin films bydifferent methods. Photo- and e-beam lithography incombination with dry or wet etching are used todefine patterns with dimensions on um- and sub-^m-scale for device application. Nanobridges are underdevelopment to study current transport in one di-mensional high-Tc filaments and Josephson junc-tions. A considerable enhancement of critical cur-rents has been obtained.

176 THE CENTRE FOR


A4: Josephson Junctions Based on HighTemperature Superconductors

It is difficult to fabricate tunnel junctions using highT c superconductors. Part of the reason for this is theshort coherence length of HTS, and the extremeprocess conditions in the attempted fabrication. Thisis in sharp contrast to the traditional low transitiontemperature superconductors, where stable highquality tunnel junctions are made routinely with highintegration. Fc. the cuprates with Tc above 77 K, noBCS type I-V curves have been obtained yet. Themost promising Josephson weak links are grainboundary weak links formed on bicrystal substratesoron a bi-epitaxial film. However, the artificial grainboundary junction (AGBJ) on bicrystals needs thesespecially prepared substrates, and the bi-epitaxialjunction has a limited parameter range. In both cases,the current transport occurs along the favorable a-and b-directions, for c-axis oriented films. We arepresently engaged in fabrication of bicrystal weaklinks. The AGBJ made in high transition tempera-ture (Tc> 70 K) superconducting (HTS) materials,is today maybe the most interesting kind of weaklinks that can be -tudied in this field. It has the i>estcurrent-voltage (I-V) characteristic (almost identi-cal to the traditional resisiively shunted low Tc

junctions), the tunneling takes place in the a-b planefor c-axis oriented films, the weak link formation iswithin 5 Å, and the junction characteristics arereproducibly dependent on the misorientation of thegrains. Other structures that have been examined atChalmers include diffusion type microbridges, stepedge junctions, and bi-epitaxial grain boundary junc-tions. In the diffusion type microbridge, a thin stripof aluminum isdiffused into the natural grain bounda-ries in a narrow region of a YBCO film. This methodis fairly reproducible, but relies on the film growthand actual film morphology. In the second case, astep is formed in the substrate, and a YBCO layer isgrown on top of this structure. The step induces grainboundaries, which form Josephson weak links. Prom-ising results have also been obtained for bi-epitaxialgrain boundary junctions recently.

A5: Parametric amplifiers and tunnel junctionsbased on Low-Tc superconductors

World-record low noise temperatures of Josephsonparametric amplifiers operated very close to the firstnon-linear bifurcation 1/1 and l/2).TosB=3+-4Kat9 GHz. The Figure shows the amplifieroutput noise

vs temperature on the input: P=kAfG(T+TDSB).Later measurements ha"e displayed lower noisethan predicted by the Heisenberg uncertaintety rela-tion, T<hf/kB. See e.g. H.K.Olsson and T. Claeson,J. Appl. Phys. 64,5234, (1988), J. Edstam and H.K.Olsson, Superconducting Devices and Their Appli-cations, eds. H. Koch and H. Liibbig, SpringerVerlag, Berlin 1992, pp 224-227.

Z 3

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TEMPERATURE [K]

A6: SQUIDs based on High Tc superconductorsWorld record low noise levels of YBCO SQUIDsfabricated on (Y)ZrO bicrystal substrates. Se= 10 -29 J/Hz at 77 K which compares well with LTcSQUID sensitivities at 4 K, see figure below. H.K.Olsson et al. Appl Phys. Lett. 61, 861 (1992).

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20 40 60 80 100Temperature |K|

Noise sources: Identified two different 1/f noisecontributions to the noise: film and junction voltagenoise. Close to Tc, a peak in the noise power wasobserved due to small pinning energies for magneticvortices in the superconductor. At lower tempera-tures, the noise was found to increase due to largecurrents being forced through the junction electrontraps. Minimum noise at 85 K, see figure below.H.K. Olsson et al. IEEE TRans Magn 1993, to bepublished.



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70 75 80 85TEMPERATURE [K]

A7: Coupled high frequency cscillatorsand High Tc mixers

The first demonstration of heterodyne mixer usingHTc materials. The Figure shows the mixing prod-uct vs bias voltage of the HTc junction and in theinset the point contact mixer sitting in a waveguide.Signal frequency = 70 GHz and IF ouput frequency= 50 MHz. Note V=hf/q since lql=2e also for HTc.H.K. Olsson et al., J. Appl. Phys. 62,2113, (1987).

.1 « •

200 400 600 800VOLTAGE

A8: Flux Flow OscillatorsA flux flow oscillator consists of a long narrowJosephson junction. Since the junctio.t is severalJosephson penetration depths long, it can have sev-eral magnetic flux quanta trapped in the barrierregion. These fluxons follow soliton solutions (theperturbed sine-Gordon equation) and can move alongthe junction. If a current is applied through thejunction in the presence of a magnetic field, fluxonswill nucleate atone end of the junction and be movedby the Lorentz force. If the fluxon velocity ap-proaches the wave velocity for electromagnetic wavepropagation through the junction, energy will betransferred from the fluxon motion to the electro-

magnetic wave and power is generated. The FFO issimilar to a traveling wave tube in its operation. TheFFOcan deliver appreciable power, but the linewidthhas been an open question. We were able to deter-mine the composite linewidth of twoFFOs to 2.1 MHzin the band 280-330 GHz. The coupled power to a10 Q microstripline was about 0.5 (J.W, which ismore than enough to pump an SIS mixer in this band.Furthermore, we demonstrated that the output powercould be tuned with very little frequency shift bysimply varying the current biasing of the FFO on itsresonant step. This is of utmost importance for thepractical use of integrated superconducting localoscillators. Similar circuits are investigated in thehigh-Tc program, and recently, evidence was seenfor the same fluxon motion.

A9: 1 THz spectral analysis using High-Tcsuperconductors

The figure shows an example of a spectrum obtainedwith a HTc integrated Josephson junction andmicrostrip resonator. A broad band coverage isachieved by simply measuring the IV-curve of thejunction (f=2eV/h) and detecting the resonances.Note the operating frequency of this novel spectrumanalyzer: 0-200 GHz. One can imagine these de-vices being used to investigate dielectric materials,gases, conductors, etc. A FIRST with HTc supercon-ductors! The frequency range has now been ex-tended to 1000 GHz. J. Edstam et al., Appl. Phys.Lett. 62,896, (1993).

0.6

50 100 150 200f|GH/.|

178 THE CENTRE FOR


AlO: Rapid Single Flux Quantum Devices andCircuits

The project aims to develop a new family of RapidSingle Flux Quantum Circuits (RSFQ) based onhigh-Tc superconductors. The idea tode velop digitaldevices where the logic unit is presented by a singleflux quanta of magnetic field resulted in a largefamily of low Tc integrated circuits. Recently,Conductus (USA) and our laboratory have provenexperimentally that RSFQ circuits can be based onhigh-Tc superconductors. For the further develop-ment of high-Tc RSFQ, electronic Josephson junc-tions, suitable for integrated circuits and multilayerstructures, will be developed.The project includesintensive simulations of RSFQ integrated circuitsand fabrication of integrated circuit.

A l l : Digital Elements Based on Flux Row InHigh Tc Superconductors

Vortex f low

region

Control current

Transistor action

A very promising vortex transistor has come out ofthe work with high-Tc films (Martenset. al., Sandia).Due to the lower pinnhig and smeared onset of HighTc superconductivity it is possible to bias a thin filmstrip in a stable way (non-heating). By placing acontrol current lead close to the strip, vortices areinduced in the film and are accelerated via theLorentz force. A transistor action is obtained.

A12: The vortex glass (H>Hc l) and coherenceeffects (H=0)

This is a hot scientific field.The behavior of HTcsuperconductors in magnetic fields differs from thatencountered in LTc superconductors. This fact hasimportant implications for large scale applications,thin film applications and the theory build-up aroundHigh-Tc superconductivity. Most large scale appli-cations include a superconducting coil which gener-ates a large self-field in which the superconductor isoperated e.g. levitating trains, electric motors, en-ergy storage etc. In electronics, a promising novel

three terminal device has recently appeared that usesthe motion of magnetic vortices in a superconduct-ing film. High speed (>90 GHz) and compatibilitywith slower semiconducting devices make themextremely interesting for applications. The theoryfield around these vortex phenomena has virtuallyexploded in size the last few years and severalelaborate models to explain the behavior are dis-cussed. For instance, a freezing into a vortex glassstate much like the spin glass model seem to describeseveral features well. Ourexperiments reproduce thecritical dynamics predicted for a vortex glass phasetransition.H.K. Olsson et al., Phys. Rev. Lett. 66,2661 (1991)and H.K. Olsson and R.H. Koch, Phys. Rev. Lett.,68,2406, (1992).

A13: Low Noise Quasl-Particle (SIS) Mixers

Integrated SIS (superconductor-insulator-supercon-ductor) mixers is a collaboration with Yale Univer-sity on developing SIS mixers with both integratedfixed broadband tuning and with electronically on-chip tuning using the non-linear quasiparticle reac-tance of a tuning SIS array. The first direct measure-menv and observation of the quantum conductanceand susceptance for a large voltage bias interval inboth the low and high signal limits was obtained. Asuperconducting detector electronically tuned by anintegrated array of SIS junctions using the nonlinearquantum susceptance was also demonstrated.

A14: Hot Electron Devices

Hot electron bolometers, mixers, fast switches andmodulators are applications that might emerge fromultra thin and narrow high-Tc films. This program isconducted together with the Moscow PedagogicalUniversity and Department of Microwave Technol-ogy. The purpose of this study is to combine studiesof non-equilibrium states in high-Tc materials and toprovide a new generation of advanced detectors for"difficult" bands in e.g. the infrared. Switching timesof ~ 10 ps or modulation frequencies of the order of30 GHz or more are predicted for radiation rangingfrom microwave to infrared. The physical phenom-ena is based on electron heating effects. Incomingradiation is interacting with the electron system,which is relaxed by electron-electron and electron-phonon scattering. The hot phonons are then relaxedby other phonon or electron collisions or they diffuseaway from the interaction region into the substrate or



film banks. Non-equilibrium electron heating can beaccomplished by sufficient removal of hot non-equilibrium phonons from the interaction region, ifthe electron-electron scattering time is much shorterthan theelectron-phonon time. Theelectron-phonontime should be short for fast responses. This situationwill allow for non-equilibrium electron heating,where the electron gas will be at an elevated effectivetemperature compared to the lattice temperature.Potential applications for the hot electron effects inhigh-Tc are bolometers, microwave through infraredmixers, fast switches or demodulators foroptoelectronics, etc. By studying the upper cut-offfrequency of the beating signal in a mixer experi-ment, the electron phonon time can be obtained. Wehave obtained an increased sensitivity by using anew modulation technique and both this techniqueand pulsed laser (20 ps lasers, X=0.85 \an) measure-ments are in accordance, showing that the supercon-ducting hot electron sensor has a response timeshorter than 30 ps.

A15: Three-Terminal DevicesThe project is directed towards development ofthree-terminal Josephson devices with asemiconducting channel controlled by electric field.The devices are based on low-Tc superconductorswith GaAs channel or high-Tc superconductors. Inthe latter case we have shown that semiconductingchannel can be created by using YBCO 45° grainboundaries on ZrO2 bi-crystals, or doped bi-crystaljunctions. Another line in the project will be thedevelopment of artificial semiconducting channelsby using semiconductors as PrBaCuO, BaZxOs ordoped YBaCuO. The underlying phenomena in bothcases are not well understood and the effort will bemainly to study the physical processes. Develop-ment of a device model and study of microwave andnoise properties will be performed.

A16: Local Structure by XAFSX-ray Absorption Fine Structure (XAFS)spectroscopy can be used to study the local environ-ment around absorbing atoms. Collaborating withresearchers at Xerox, Stanford, UCSC, and manysample suppliers, we have investigated high Tc

superconductors. The problems have included theeffect of substitutions, like Fe, Co, Zn, and Ni inYBCO (where we see local distortions, chain func-tion, clustering etc), the effect of oxygen depletion,

and varying oxygen distances (tentatively coupled todifferent valence charge distributions) in doped su-perconductors based on BaBiOj.

B. Nanofabrlcatlon and Nanotechnology

B l : Development of Technology for NanometerFabrication

Development of positive and negative resist tech-nologies, proximity corrections, lift-off and etchingtechniques. CAD design implementation with inte-grated electron exposure simulation tools. Experi-mental methods to verify simulations for differentmaterial combinations. Selective etching using NiCrmasks on Si and GaAs substrates has been studied.Good selectivity could be achieved using a chlorinebased chemically assisted reactive ion beam etchprocess.

B2: Examples of Projects Utilizing theNanometer Laboratory

The nanometer fabrication facility is used by severalgroups at Chalmers, Linköping, Uppsala and Stock-holm as well as some groups in Copenhagen, Hel-sinki, and Sofia. Here, we report on activities by CTHgroups in the form of research projects.

Development of an ultra high speed GaAs highelectron mobility transistor(HEMT) technology.So far, MESFETs and different HEMTs have beenfabricated successfully. The produced componentsare far better than commercial ones and comparablewith the best ones reported in litterature with similargatelengths. Current activities concentrate on de-creasing the gatelength down to approximately 0.1Hm by using electron beam lithography. The pro-jected and measured fmax is above 300 GHz. Inte-grated millimeter wave circuits like monolithic am-plifiers and receivers for low-noise applications arebeing developed and have been tested successfullyup to 1 OOGHz. The project is supervised by H Zirath,dept of Applied Electron Physics and utilizes thenanometer lab.

Comer reflector lasers.Microfabrication of opto-electronic and electroniccomponents on a single chip is a growing field ofresearch. It is desirable to place driver circuits andlasers for external communication on the same chip.

180 THE CENTRE FOR


The 8 micrometer diameter Chalmers Emblem ismade of Au-Pd lines on bulk silicon using electronbeam lithography. The smallest linewidth is about50 nm.

A gate structu.e on top of a GaAs/AIGaAsheterostructure for observation of a single elec-tron tunnel effects and 0-1 dimensional transportphenomena. The 2DEG under the gates is de-pleted when a voltage is applied defining two dotsconnected by point contacts.

The conventional method of forming the laser mirrorby cleaving the GaAs crystal can only be employedfor one mirror and only if the laser is placed at theedge of the chip. The other mirror has to be formedby etching. If the laser only needs to emit radiationthrough the cleaved mirror, the other plane mirrormay be replaced by an etched comer reflector withtotal internal reflection, which also gives a bettermode formation in the laser cavity than two planemirrors. To reach highest possible quality of thefacets, the mask is defined by electron beam lithog-raphy and the facets are dry etched using an ionbeam. A new type of surface emission laser hasrecently been developed, using a combination of twoetched corner reflectors and a special surface grat-ing, made by e beam lithography. The emissionprofile of such a device is better than what you getfrom a conventional edge-type laser. Since the radia-tion isemitted vertically, the design can be utilized inintegrated arrays very easily, and may be interfacedto other systems. The threshold current density ofthis laser is equal to or better than for a conventionaledge-type laser.

- Mats Hagberg and Torgil Kjellberg, Dept. ofElectrical Measurements and Optoelectronics.

Multilevel phase holograms.

It is possible to fabricate computer generated holo-grams that will have a high utilization of the light.e.g.for display purposes or power laser machining.Holograms with almost continous control (63 levels)of the surface topography have been realized byelectron beam lithography. This level of control isunique among the groups working with this kind ofdiffraction optics. Hologram diffraction efficienciesas high as 84% of the theoretically predicted 89%efficiency were measured by a group at AppliedElectron Physics. This the highest reported value todate.- M. Ekberg, M. Larsson, S. Hård, Appl.El.Phys., incooperation with B. Nilsson, nm-lab.

Single traps and quantum transportin nanometer size MOSFETs.The purpose of the project is to study single electrontraps and quantum transport in nanometer size sili-con MOSFETs. Together with electron beam lithog-raphy, a special dry etching technique is developedfor the fabrication of the small MOSFETs. So far,etched MOS structures in the 80 nm range has beenfabricated. Traps and "telegraph noise" have beenstudied in diodes fabricated with sub-micron dimen-sions. The project is pursued by the dept of SolidState Electronics (Engström, Andersson, Xiao) withaid from and using the nanometer laboratory.



Artificial micro- and nanostructures forbiomaterials research and applications.In order to further understand the interaction be-tween living tissue and foreign material on thecellular level, micro- and nanofabrication techniquescan be used to produce test surfaces having control-led surface topographies and compositions. It ispossible to systematically modify the interactionsurfaces, one property at the time. Free particles insuspension can be produced with similar methods,with well controlled size, shape and composition, forinteraction with living cells.-The Biomaterials Consortium with Julie Gold andBengt Nilsson as participants.

C. Mesoscoplc Physics

C l : Single Charge Tunneling In Metallic andSuperconducting Structures

The tunnelling of an electron from one electrode toanother through a large potential b?. rier occurs inpackets of charge having a unit value of e. If thecapacitance of the tunnel junction is small enough,the energy required to charge the junction capaci-tance with a single electron, EQ= e2/2C, can becomequite substantial. This charging energy can act toinhibit tunneling of the electron. This is the essenceof the Coulomb blockade. The charging energy canalso give rise to a strong correlation of tunnelingevents in multi-tunnel junction circuits where thetunnel junctions are close to one another. Further-more, by changing the charge distribution in multi-tunnel junction circuits by means of external gateelectrodes, the coulomb blockade can be modulatedresulting in a single electron transistor effect.

In superconducting tunnel junctions, the tunne-ling occurs via paired electrons (Cooper pairs),having charge 2e. Several pairs exist in a phasecoherent state, and the strength of the phase coherenttunnelling of Cooper pairs is given by the Josephsoncoupling energy EJ. The phase and charge are quan-tum mechanically conjugate variables in the macro-scopic, phenomenological description of the super-conducting junction. The Coulomb blockade in thesuperconducting junction with EJ ~EQ, manifestsitself in a radically different way than that of thenormal tunnel junction.

Coulomb blockade phenomena are of substantialinterest forpotential applications inelectronics. These

phenomena are also of general scientific interestsince they are an example of macroscopic quantumphenomena, which presents a new experimentalrealm for testing the predictions of standard quantummechanics. Our group is engaged is several experi-ments which are of both applied and general scien-tific interest:

• Two dimensional arrays of tunnel junctionshave been studied in both the normal andsuperconducting state. We have recentlyinvestigated the role of the Josephson couplingenergy and its effect the threshold voltage andactivation energy for transport in insulatingarrays.

• One dimensional arrays of tunnel junctionshave shown the existence of SET oscillations.Simulations and experiments on coupled onedimensional arrays have been carried out tolook for synchronisation of tunneling in eacharray.

• Superconducting multi-junction experiments inloop geometries have shown the combinedeffect of phase and charge quantization in thecircuit. These devices obtain modulation of theI-V curve with both magnetic flux and gatevoltage.

• Current biased circuits are achieved by insert-ing high resistance leads (ca. 30kQ/um) in theleads, very close to the jnnel junctions. Suchexperiments allowed the observation of Blochoscillations and SET oscillations in a singletunnel junction.

C2: Single Charge TunnelingIn Semiconducting Structures

Small conducting islands can be confined by anelectrostatic potential in a two-dimensional elec-tron-gas (2DEG), which is an epitaxially grownheterostructure. The islands are contacted by quan-tum point contacts, with an adjustable tunnelingprobability for the electrons. It is in this way differentfrom the metallic system with oxide tunnel barriers.The transport through a quantum dot is affected bythe energy level spectrum of the dot, magnetic fluxespenetrating the dot, and the charging effects. Charg-ing effects in semiconductors is a field of greatinterest. Current steps have been demonstrated in aturnstile. Single electron transistors have been made.

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Cotunneling effects and the energy level spectrahave been studied.

We have observed magneto-conductance oscil-lations of a dot at low magnetic fields, with a periodcorresponding to the Aharonov-Bohm period of arinj. These oscillations were not expected at lowfields, only at high fields where the current is trans-ported in edge channels. They coexist with thecharging effects. Thus it is possible to investigate thedepopulation of the Landau levels of the dot bysingle electrons.

C3: Mesoscopic transport phenomenain wires and rings

We have measured the magneto resistance and thecurrent voltage characteristics on a large number ofmesoscopic size rings and wires. In many of thesesamples we placed superconducting electrodes ontop of the current leads, or alternatively on "stubs"perpendicular to the current leads. These supercon-ducting electrodes act as "mirrors" where electronsare Andreev reflected.

Aharonov Bohm effect: In rings without super-conducting mirrors we observe h/2e oscillations ofthe magneto resistance. The amplitude of theseAharonov-Bohm oscillations are up to 400 timeslarger when superconducting "mirrors" are presentcompared to a ring without mirrors.

For samples with "mirrors" we also observe h/4eoscillations which are due to Phase coupling be-tween electrons and the superconducting conden-sate. As an electron is Andreev reflected at the SNboundary it acquires the phase of the superconduc-tor. This results in the h/4e oscillation of the magnetoresistance.

Conductance fluctuations of the resistance isobserved for both rings and wires with "mirrors". Asthe superconductivity is suppressed by a magneticfield, the change in resistance can be both positive ornegative.

The response of a ring to an electric field suppliedby a gate (an attempt to observe the electrostatic A-B effect) showed that screening in a ID system ismuch less effective, than in a 3D system.

C4: Integrating metaHbased single electronicswith semiconductors

The aim is to impedance-match SET transistors withthe environment, hereby increasing the maximumoutput frequency by several orders of magnitude.

We will need to integrate small field effect transis-tors directly below or beside the SET output tominimize stray capacitance from leads.

D. Scanning Probe Microscopy

Scanning probe microscopy (SPM) is a growingfamily of high resolution techniques employing thesame principle as in the scanning tunneling micro-scope (STM), but with the tunneling tip replaced byanother local probe. One common type of probemicroscope is the atomic force microscope (AFM)where repulsive forces are measured using a tech-nique similar to an ordinary record player. With theAFM non-conducting samples are possible to imagewith a resolution down to the atomic scale.

A new extended laboratory for scanning probemicroscopy has been set up during 1992. The labo-ratory is a joint effort between the Materials ScienceCentre, five physics groups (Claeson, Kasemo,Nordén.Granqvist, and Rosén), twochemical groups(Hjertberg and Bertilsson), and the educational de-partment. The SPM-lab consists of two commei rialSTM/AFM (for use in air, liquid, and electrolyte)and a number of home-built probe microscopes.

D l . Development of Scanning ProbeMicroscopes

Air-liquid STM/SPM. An STM for use in air andliquid has been developed. The microscope is spe-cially designed to allow other probes to be inserted.

SICM. A probe microscope suitable for biologi-cal samples is the scanning ion conductance micro-scope (SICM). Using glass pipettes as the probe wehave reached a resolution of about 0.S (am on a leafsample. The resolution in the SICM is limited by thesize of the pipette aperture. Standard pipettes be-come increasingly fragile when the diameter of theaperture is made smaller. To increase the resolutionwe have started a development of a new kind ofpipette with aperture openings down to 5 nm.

Low-temperature. To study tunneling phenom-ena, superconductors and mesoscopic physics at lowtemperatures STMs suitable for operation at heliumtemperatures has been build. The STMs are suitablefor operation down to 1.3 K and 50 mK.



D2. SPM Studtes of High Tc Superconductors;Film Growth, SET

A number of important questions related to themicTostructure of YBCO high Tc films have beeninvestigated. One is the unknown nature of thedefects responsible for flux pinning. Another ques-tion concerns the nucleation and growth mecha-nisms of the films. Our STM measurements showedthat changes in surface morphologies occurred whenthe substrate temperature during deposition wasvaried. These variations couL be related to a de-crease in critical current and increase in surfaceresistance with increasing temperature.

An extensive study has been performed using acombination of AFM and TEM on the early stages ofgrowth of YBCO thin films. Important micro-structural characteristics, which are strongly corre-lated to properties such as the critical current densityand the transition temperature, are established atthese early stages of growth.

We have also studied Tl2Ba2CaCu2O8 high Tc

films. Using the STM we observed a high density ofnm-sized particles on the surface. Tunnelingspectroscopicmeasurementon these samples showedlarge coulomb blockades. In contrast to previousexperiments that have been performed at a tempera-ture below IK, these measurements were made atroom temperature.

D3. Other STM/AFM Studies In AirBiomaterials. Titanium oxide is a successfulbiomaterial. However, the mechanism for thebiocompatibility is not known. One influencing fac-tor can be the topography at the nanometer scale. Toinvestigate the topography at this scale, we per-formed STM/AFM experiments on different sam-ples. The results are used for in vivo or cell studies toget correlation between surface roughness and bio-compatibility.

Other studies include AFM measurements ofsurface morphology of CaF2 films as a function offilm thickness, deposition angle, rate, and pressurefor understanding of the dynamics and morphologyof growing rough surfaces.

D4. Metoscopic and Superconductor StudiesUsing Low-Temperature STM

A new method has been introduced to study electrontransport in mesoscopic samples. The electric fieldfrom an STM-tip is used to locally influence a

mesoscopic object. The mesoscopic sample is apoint contact made using the STM-tip at 1.2 K iustbefore the measurement. We detect abrupt changesin the mesoscopic signal both as a function of the tipposition and tip-sample voltage. They could beinterpreted as due to spatial shifts or changes in theactivity of scattering centers in the sample.

Scanning tunneling microscope imageof graphite atoms.

High-temperature superconductors (YBCO).Scanning Tunneling Microscope image showingthe layered structure of this material.Also, note the screw dislocation.

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PublicationsPh.D. Dissertationsand Licentiate DfssertlonsP. Delsing, "Single Electron Tunneling in Ultrasmall

Tunnel Junctions", 90, Thesis.M. Danerud, "Thin Films and Optical Detectors Made of

G. Brorsson, "Laser Deposited Thin Films of the HighTemperature Superconductors YBaCuO andBiSrCaCuO",June91.

P Å Nilsson, "Thin Films of Y B a ^ O ? deposited by CO-evaporation, Josephson Junctions, and dc-SQUIDs,June 91.

Y. Zhang, "Theoretical and Experimental Studies of theFlux-Flow Type Josephson Oscillator", October 91.

P. Davidsson, "Symmetric Scanning Tunneling Micro-scopes for Ultra High Vacuum and Very Low Tem-peratures", April 92.

J. F.dsiam, "Lumped Arrays of Josephson Junction Oscilla-tors", March 92.

P. Davidsson, "Symmetric Scanning Tunneling Micro-scopes for Ultra High Vacuum and Very Low Tem-peratures", April 92.

J. Edstam, "Lumped Arrays of Josephson Junction Oscilla-tors", March 92.

H. Olin, "Scanning Probe Microscopy: Design and Appli-cations", 93, Thesis.

Rim Fabrication and Properties1. Elemental Profiling Through Superconducting

BiSrCaCu Oxide Layers Deposited by LaserAblation on Different Substrate Materials.E.U. Engström, Z. Ivanov and A. Loading, Proc. Conf.on Analytical Chemistry - EUROANALYSIS VII,Vienna. Austria, 1990.

2. Superconducting (Bi,Pb)-Ca-Sr-Cu-0 Thin FilmsPrepared in Situ by Laser Ablation.Z. Ivanov and G. Brcrsson, Appl Phys Lett. 5j5_, 2123(1989).

3. High Quality YBCO Thin Films • Laser Deposition,Co-Evaporation, and Device FabricationJ.A. Alarco, G. Brorsson, T. Claeson, M. Danerud, U.Engström, Z.G. Ivanov, P-Å. Nilsson, H. Olin, and D.Winkler, Physica Scripta 44, 35-101 (1991).

4. In situ YBCO Thin Films Made by Laser Deposi-tionG. Brorsson, Z. Ivanov, and P-Å. Nilsson, Science andTechnology of Thin Film Superconductors 2, edited byR.D. McConnel and R. Noufi, Denver, Colorado, 1990,pp 169-175.

5. Study oT in situ Laser Deposited YBCO Thin FilmsG. Brorsson, J.A. Alarco, Z.G. Ivanov, H. Olin, P-Å.Nilsson, and T. Claeson, J. of the Less-CommonMeials, 164&165,383-390,1990.

6. In-situ dc Sputtered High Tc Y-Ba-Cu-O FilmsS. Zarcmbinski, J. Ramos, Z. Ivanov, and T. Claeson.J. of the Less-Common Metals, 164&165,329-335,1990.

7. Ac-Impedance at the Superconducting Vortex GlassTransition.HK. Olsson, R.H. Koch, W. Eidelloth, and R.Robertazzi. APS Cincinaui, March 1991, and EPSExter, April 1991 and invited at 5M3I Intermagconference, Pittsburg, June 1991, invited Swedish HTcannual meeting, May 1991.

8. Observation of Critical Scaling Behavior in the acImpedance of the Onset of Superconductivity in aLarge Magnetic FieldH.K. Olsson, R.H. Koch, W. Eidclloth, and R.Robertazzi. Phys. Rev. Letters 66,2661 (1991).

9. Growth and Properties of NdGaO3/YBCOMultilayer StructuresYu. Boikov, G. Brorsson, T. Claeson, and Z.G. Ivanov,E-MRS, Int. Conf. Adv. Mat.: High Tc SuperconductorThin Films, ed. by . Correra, Elsevier Science Publ.,1992, p. 721-726.

10. YBCO Thin Films on Yttria Stabilized Zirconia -Growth and PropertiesJ.A. Alarco, G. Brorsson, t. Clacson, Z.G. Ivanov, andM. Lövgren, E-MRS, Int. Conf. Adv. Mat.: High TcSuperconductor Thin Films, ed. by L. Correra, ElsevierScience Publ., 1992, p. 647-652.

11. Very Thin YBaCuO Films Made by CoevaporationM. Danerud, P.Å. Nilsson, and J. Alarco, E-MRS, Int.Conf. Adv. Mat.: High Tc Superconductor Thin Films,ed. by L. Correra, Elscvicr Science Publ., 1992, pp421-426.

12. Epitaxial Growth and Properties of YBazCuaO-VNdGaOj/YBa2Cu3O7.d Trilayer StructuresYu.Boikov, G.Brorsson, T. Claeson, and Z.G.Ivanov,Appl. Phys. Lett. 59,2606 (1991).

13. YBCO thin films on Yttria-stabilized Zirconia andLaAIO3: growth and propertiesJ.A. AJarco, G. Brorsson, T. Clacson, Z.G. Ivanov, M.Lofgren, and P.Å. Nilsson, Physica C, 185-189,2017-2018(1991).

14. Scanning Tunneling Microscopy of Laser DepositedYBCO Thin FilmsH. Olin, G.Brorsson, P.Davidsson, Z.G.Ivanov,P.Å.Nilsson, and T.Clacson, Ultramicroscopy 42-44,734 (1992).



15. Laser-deposited PrGaO» films on SrTiOj substratesand in 15.15. YBa2Cu3O7/n-Ga(VYBa2Cii3O7Trilayers,G. Brorsson, P.Å. Nilsson, E. Olsson, SZ. Wang, andT. Claeson. AppL Phys. Lett 61, (1992).

16. Growth and Properties of a Multilayer SystemBased on Y ^ C i ^ O , and Amorphous Y-ZrO2

Yu. Boikov, Z. G. Ivanov, J. A. Alarco, G. Brorsson,and T. Claeson, J. Appl. Phys. 22(1), 199-202 (1992).

17. Effects of substrate temperature on the mkrostruc-ture oT YBa^CujOj-j films grown on (001) Y-ZrOjsubstrates, Appl. Phys Lett, 61723-725(1992).

18. Epitaxial growth and properties of YiPb(ZrousTio.4)03-Y,Ba2Cu30, and Amorphous Y-

Yu. Boikov, S.K. Esayan, Z.G. Ivanov, G. Brorsson, T.Claeson, J. Lee, and A. Safari, Appl. Phys. Lett., 6L528(1992).

19. Superconducting properties of electrochemicallyLi+ intercalated YBaCuO thin filmsZ.G. Ivanov, A.M. Andersson and CG. Granqvist, J. ofAlloys and compounds, J9J,343-346 (1993)

20. YBaCuO/NdGaO/YBaCuO Tri-layers by MopifiedOfT-Axis Sputtering,SZ. Wang, E. Olsson, J.A. Alarco, 7.G. Ivanov, D.Winkler, V. Langer, and P. Beraslegui, subm. to J.AppLPhys.

Processing and Junctions21. Microbridges in High-Tc Superconductors: High

IcRn ProductsZ.G. Ivanov, G. Brorsson, and T. Claeson, J. of theLess-Common Metals, 164&165,1529-1535,1990.

22. High Resolution Patterning of High-Tc Supercon-ducting Thin FilmsZ. Ivanov, P-Å. Nilsson, E-K. Andersson, and T.Claeson, Supercond. Sci. Technol. 4,112,1090.

23. High Tc Superconducting Diffusion Type WeakLinksZ O. Ivanov and T. Claeson, Physics B, 165&166 II,69-70,1990.

24. Fabrication and Properties of NTS Diffusion TypeWeak LinksZ.G. Ivanov, G. Brorsson, and T. Clacson, IEEE Trans.Magnetics Mag-21,3324 (1991).

25. Properties of Artificial Grain Boundary WeakLinks Grown on Y-ZrO2 Bkrystab.Z.G. Ivanov, P.Å. Nilsson, D.Winkler, J.A. Alarco, G.Brorsson, T. Claeson, E.A. Stepantsov, and A.Y.Tzaknchuk, Supercond. Sci. Technol. 4,439-441(1991).

26. Grain boundaries in YBaCuO thin films - a semi-conductor?Z.G. Ivanov, T. Clacson, R.I. Shekhler, D. Winkler,E.A. Stepantsov, and A.Y. Tzalcnchuk, in Proceedingsof the Joint Nordic Spring Meeting '92, edited by P.-A.Lindgård (Risö-R-628(EN)), Risö National Laboratory,Roskilde, Denmark, 7-10 May, 1992.

27. Properties of YBCO junctions and SQUIDs on YSZbkrystalsP.-Å. Nilsson, Z.G. Ivanov, D. Winkler, H.K. Olsson,G. Brorsson, T. Claeson, E.A. Stcpantsov, and A.Y.Tzalenchuk, Physica, vol. C 185-189, pp. 2597-2598,1991.

28. Metal-Doped Artificial Grain Boundary WeakLinks in YBCO FilmsE.A. Stepantsov, A.Ya.Tzalcnchuk, Z.G. Ivanov, andT.CIacson, ZI in Materials and CrystallographicAspects of High-Tc Superconductivity, edited by E.Kaldis, Erice, Italy, 1993, May 17-29,.

29. Sub-micron Size, High Current Density Nb/PbBiWindow Tunnel JunctionsJ. Edstam and H.K. Olsson, SQUID'91, subm.

30. Narrow YBCO Microbridges in Lltrathin LaserDeposited FilmsM. Dancrud, M.E.Gershenson, Z. Ivanov, D.Winklcr,and T.Claeson, Physics C, 185-189,1939 (1991).

31. Microstructure of an YBa2CujO7.5 artificial gra'"boundary weak links grown on a 0- 45° (001) tilt Y-ZrO2 bicrystalsJ. A. Alarco, E. Olsson, Z. G. Ivanov, P. Å. Nilsson, D.Winkler, E. A. Stepantsov, and A. Ya. Tzalcnchuk,Frontiers of Electron Microscopy in Materials Science,Oakland, California, April 21-24,1992. to be pub-lished,.

32. YBaCuO Josephson weak links based on shallowion beam etched steps in MgO substratesJ. Ramos, Z. G. Ivanov, E. Olsson, and T. Clacson,Proc. BIHTS'92, World Sci, Singapore, to be pub-lished.

33. Properties of ion beam stimulated bi-epitaxialJosephson junctionsJ.H. Ramos, Z.G. Ivanov, E. Olsson, and T.CIacson,IEEE Trans.Magn., to be publ.

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34. Crossovers and Vias in YBaCuO/PrGaO3/YBaCuOTrilayer StructuresNilsson, P. Å., Brorsson, G., Olsson, E., Ivanov, Z. G.,& Claeson, T. (1992). IEEE Trans. Magn., subm.

35. Weak Links and dc-SQUIDs on Artificial Non-Symmetric Grain Boundaries in YBa2CujO7^Z.G.lvanov, PÅ.NiIsson, D.Winkler, J.A.Alarco,T.Clacson, E.A.Stepantsov, and A.Ya.T/alenchuk,Appl. Phys.Lett. 59,3030-3032 (1991).

36. Sub-micron sized, high-current density Nb/PbBiwindow tunnel junctionsJ. Edstam and H.K. Olsson, Superconducting Devicesand Their Applications, eds. H. Koch and H. Liibbig,Springer Verlag, Berlin 1992, pp 224-227.

High frequency effects37. Design of a Lumped array of Josephson Junction

OscillatorsJ. Edstam and H.K. Olsson. IEEE Trans. Magn.,MAG-29, (1993), to be published.

38. Direct detection of high frequency resonances inbkrystal Josephson junctionsJ. Edstam, P.Å. Nilsson r id H.K. Olsson AppliedSuperconductivity Conference, Chicago, Ai g 1992.

39. 100 GHz Oscillations on Monolithic HTC ChipJ. Edstam, P-Å. Nilsson, E. A. Stcpantsov, and H.K.Olsson. Appl. Phys. Leu., 62,896,1993.

40. On-chip Diagnostic of HTC Superconductors atmm-Wave FrequenciesJ. Edstam, P.-Å. Nilsson, E. A. Stcpantsov, and H. K.Olsson. J. Alloys and Compounds, 1993. To bepublished.

41. Broad band microwave spectroscopy of cooledmonolithic circuitsH. K. Olsson and J. Edstam. INTERMAG 93, Stock-holm Sweden, April 13-16 1993.

42. London penetration depth of YBCO for the fre-quency range 80-700 GHzJ. Edstam and H.K. Olsson. XX International Confer-ence on Low Temperature Physi. s, Eugene OR, Aug4-11 1993.

43. Integrated microstrip resonator structures usinghigh-Tc materialsJ. Edstam and H.K. Olsson, XX International Confer-ence on I ow Temperature Physics, Eugene OR, Aug4-11 1993.

44. Scaling behavior at the vortex glass transitionH.K. Olsson, R.H. Koch, W. Eidelloth, and R.Robcriazzi. Physica C 185-189,1815 (1991).

45. Observation or a peak in the real part of the rf-conductivity, Re|s(T)|, of YBaCuOH.K. Olsson and R.H. Koch. Physica C 185-189,1847(1991).

46. Comment on "Observation of Conductivity Coher-ence Peak _." by Holzcer et. al. PRL 67,152(1991)H.K. Olsson and R.H. Koch. Phys. Rev. Lett., 68,2406,(1992).

47. A quasiparticle-tuned superconducting mixerN.G. Ugras, A.H. Worsham, D. Winklcr, and D.E.Probcr, Appl. Phys. L ett., vol. pp. to be published1993.

48. A 75-110 GHz SIS mixer with integrated tuningand couped gainD. Winklcr, A.H. Worsham, N.G. Ugras, D.E. Prober,N.R. Erickson, and P.F. Goldsmith, In NonlinearSuperconductive Electronics and Josephson Devices,(Plenum Press, New York, 1991), G. Costabile, S.Pagano, N. F. Pcuersen and M. Russo, Ed., 1991, pp.73-79.

49. Self-Induced Resonances in YBCO Bicrystal GrainBoundary Josephson JunctionsD. Winklcr, Y.M. Zhang, P.A. Nilsson, E.A.Stcpantsov, and T. Claeson, in XX InternationalConference on Low Temperature Physics, cd'tfrt byEugene, Oregon, USA, 1993, August 4-11.

50. Detection of mm and submm wave radiation fromsoliton and flux-flow modes in a long JosephsonjunctionY.M. Zhang, D. Winklcr, and T. Claeson, IEEE Trans.Appl. Supercond, to be published 1993.

51. Linewidth measurements of Josephson flux-flowoscillators in the band 280-330 GHzY.M. Zhang, D. Winkler, and T. Claeson,, Appl. Phys.Lett., vol. pp. accepted for publication.

52. Linewidth measurements of flux-flow Josephsonoscillators using a CAD designed integrated sub-mm wave receiverY.M. Zhang, D. Winklcr, and T. Claeson, in FourthInicrnalif ,al Symposium on Space Terahertz Technol-ogy, edxd by UCLA, Los Angeles, USA, March 30 -April 1,1993 1993, submitted.

53. Josephson parametric amplifiers:low noise at 9 GHzH.K. Olsson and T. Claeson, Advances in supercon-ductivity, cis Kitazawa and Ishiguro, Springer-VerlagTokyo, 1989, pp 93-97.

54. Dielectric Constant of Evaporated SiO at Frequen-cies Between 13 and 103GHz.H.K.Olsson, IEEE Trans. Magn., 25 (1989) 1115.

MATERIALS SCIENCr. 1993 187


55. Low Noise Josephson Parametric Amplification andOscillations at 9GHz.H.K.Olsson and T.CIacson, J.Appl.Phys.64(1988)5234.

56. Numerical Calculation or the Height of Velocity-Matching Step of Flux-Flow Type JosephsonOscillatorY.M. Zhang and P.W. Wu, J. Appl. Phys. 68,9,1990.

57. Effect of Losses on the Output Voltage of a Flux-Flow Type Josephson OscillatorYongming Zhang. Nonlinear Superconductive Elec-tronic and Josephson Devices, Eds. N.F. Pedersen, M.Russo, A. Davidson, G. Costabile and S. Pagino,Plenum, NY 1991, p. 145.

58. Effect of Losses on Output Voltage of Flux-FlowType Josephson Oscillator.Yongming Zhang and Tord Claeson, presented at LT-19,1990.

59. Hyper-Vortices in Granular Superconducting ThinFilmsG.A. Ovsyannikov, Z.G. Ivanov, G. Brorsson, and T.Claeson, Physica B, 165&166 II, 1609-1610,1990.

60. Hyper-vortices in high Tc superconducting bridgesG.A. Ovsyannikov, Z. Ivanov, G. Brorsson and T.Clacson, Proc. Int. Conf. Transport Prop, of Supercon-ductors, May 1990.

61. The Quantum Tunneling Currents in a Supercon-ducting JunctionA.H. Worsham, N.G. Ugras, D. Winklcr, D.E. Prober,N.R. Erickson, and PP. Goldsmith, Phys. Rev. Letters.67,3034(1991).

62. A Full-Band Waveguide SIS Receiver with Inte-grated Tuning for 75-110 GHzD. Winkler, N.G. Ugras, A.H. Worsham, DP,. Prober,N.R. Erickson, and P.F. Goldsmith, IEE E Trans.Magn. MAG-27,2634 (1991).

63. Picosecond detection of infrared radiation withYBa2Cu3O7.fi thin nimsM. Danerud, MZorin, MLindgren, V.Trifonov,E.M.G. B.Karasik, G.N.GoI'Lsman, and D.Winkler.,submitted to the proceedings of International Confer-ence on IR and MM-Waves, 1993, Sussex, England.

64. ' he Superconductor Insulator Superconductor4ixer Receiver - A Review

R. Blundell and D. Winkler, in Non-linear Supercon-ductive Electronics and Josephson Devices, Ed. byN.F. Pcdcrson, M Russo, A. Davidson, G. Costabile,and S. Pagano, Plenum, London, 1991, p. 55.

65. High Tc Superconducting IR Detectorsfrom Y-Ba-Cu-O Thin FilmsM. Lindgren, H. Ahlberg, A. Larsson, S.T. Eng, andM. Danerud, In Superconductivity Applications forInfrared and Microwave Devices (Hcinen, ed.), SPIEProc. 1292,1990, to be published.

66. Observation of Critical Scaling Behavior in the acImpedance of the Onset of Superconductivity in aLarge Magnetic FieldH.K. Olsson, R.H. Koch, W. Eidelloth, and R.Robenazzi. Phys. Rev. Letters 66,2661 (1991).

67. Ac-impedance at the superconductingvortex glass transition.H.K. Olsson, R.H. Koch, W. Eidelloth, and R.Robenazzi., J. Appl. Phys. 70,6194 (1991).

68. Mm-wave radiation in high-Tc two-dimensionalJosephson arrays,G.A. Ovsyannikov, Z.G. Ivanov, J. Mygind, NP.Pedersen, and T. Claeson, to be publ.

SQUIDs and Three Terminal Devices69. Vortex transistor devices for logic elements

Y. Zhang, G. Brorsson, M. Danerud, J. Edstam, P.Larsson, P-Å Nilsson, E. Wikborg, and H. K. Olsson.XX International Conference on Low TemperaturePhysics, Eugene OR, Aug 4-11 1993.

70. Design of Multi-Loop Input Circuits for HighTemperature Superconducting Quantum Interfer-ence Magnetometers,S. Zarembinski and T. Claeson, J. Appl. Phys., to besubm.

71. YBCO dc-SQUIDs on Y-ZrO2 BkrystalsZ.G. Ivanov, P.Å Nilsson, D. Winkler, G. Brorsson, T.Claeson, E.A. Stephantsov, and A.Y. Tzalenchuk,SQUID'91, to be publ.

72. Low 1/f noise in YBaCuO SQUIDs on bicrystal(Y)Zr02 substratesH.K.Olsson, R.H. Koch, Z.Ivanov, P-Å Nilsson, E.A.Stepanlsov, and A.Ya. Tzalcnchuk, Appl.Phys.Leu. 61,861-863(1992).

73. Superconducting Transport Properties of OhmkContactsZ G Ivanov, phys.stat.sol.(a) H i , 439 (1989).

74. Design or" Multi-Loop Input Circuits for HighTemperature Superconducting Quantum Interfer-ence MagnetometersS. Zarembinski and T. Clacson, J. Appl. Phys., Sept1992.

188 THE CENTRE FOR


75. Low l/f noise in YBaCuO SQUIDson bicrystal(Y)ZrO2 substratesHJCObson, R.H. Koch. Z.Ivanov, P-Å Nilsson, E.A.Stcpanlsov, and A.Ya.Tzalcnchuk. Appl. Physlxu. 61,861 (1992).

76. Field Effect Transistor Based on Metal-Insulator,Artificial Gran Boundary Josephson JunctionZ.G. Ivanov, T. Claescn, E.A. Stepantsov, AYa.Tzaknchuk, and R.I. Shekhier, IEEE Trans.Magn., tobcpuW.

77. Field effect devices based on metal-insulatorYBaCuO films,Yu. Boikov, G. Brorsson, Z.G. Ivanov, and T. Claeson,IEEE Trans.Magn., lo be publ.

78. dc-SQUIDs with low noise and large Devalues onBicrystal (Y)ZrQz substratesHX. Olsson, R.H. Koch, PÅ. Nilsson, and E.A.Stephantsov. IEEE Trans. Magn., MAG-29,1993, lobe published.

79. Present status and future of dr-SQUIDs nude fromhigh-Tc supercondctorsH.K. Oisson, R.H. Koch, B.Oh, R. Robertazzi, R.B.Laibowitz, A. Gupta, and W.Y. Lee. Invited, ASMmaterials research conference, San Fransisco 24-28Aug 1990, and "Science and Technology of Thin FilmSuperconductors 2", Eds. R.D. McDonnel and R.Noufi, Plenum, Press, New York, p. 563,1990.

XAFS80. Temperature Dependence of the Local Structure of

Y1Ba2Cu3O7^ with Varying Oxygen Content: AnX-Ray Absorption StudyJ.B.Boycc, F.Bridges.T.Claeson, and M.Nygren,Phys.Rev.B, 39,6555 (1989).

81. Distorted Chain Sites for Co-and Fe-Substituted

84. Occupation of Distorted Cu(l) sites by Co and Fein

F.Bridges, J.B.Boyce, T.Clacson, T.H.Geballe, andJ.M.Tarascon, Phys.Rev.B39,11603 (1989).

82. Second Neighbor Shells Around Cu in Oxygen-Deficient and Transition-Metal-DopedY,Ba2CujO7.8J.B. Boyce, F. Bridges, T. Claeson, and T.H. GebaJle,PhysicaB 158,453,1989.

83. Local Structure and Vibrations of YBaCuO withDiffering Oxygen Content and Impurities on theCopper SiteJ.B.Boyce, F.Bridges, T.Claeson, R.S.Howland,T.H.Geballe, M.Nygrcn, and J.M.Tarascon,Proc.EXAFS V.

F. Bridges, J.B. Boyce. T. Claeson. T.H. Geballe. andJJvl. Tarascon, MaLRes.Soc.Proc. 143,163 (1989).

85. X-Ray AbsorptMi Study of Superconducting

T. Cbeson, J.B. Boyce, F. Bridges, T.H. Geballe, J.M.Remeika, and A.W. Sleight. Physica C162-164,544(1989).

86. Substitution on the Cu Sites in YiBajCusEvidence for Distorted Chain Sites for Co-and Fe-Substituted MaterialF. Bridges, J.B. Boyce, T. Claeson, and J.M. Tarascon,PhyskaC162-164,969 (1989).

87. Second Neighbor Shells Around Cu in Oxygen-Deficient and Transition-Metal-Doped

J.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe,PhysicaB 158,453 (1989).

88. X-ray absorption of BaBiOj and superconductingBaBio.25Pbo.75Q,J.B. Boyce, F.G. Bridges, T. Claeson, T.H. Geballe,and J.M. Remeika, Phys. Rev. B 41,6303,1990.

89. Local structure about Ni atoms in Ni-substituted

F. Bridges, J.B. Boyce, T. Claeson, T.H. Geballe, andJ.M. Tarascon, Phys. Rev. B 42 2137.1990.

90. XAFS Determines Mini-Clusters ofNi-0 in NiDoped YBa2Cu3O7.fiJ.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe, andJ.M. Tarascon, Supercond. Sci. Techno!. 4,343 (1990).

91. Local Structure of Ni in YBa^Cu wNi.aujbO?.*J.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe, andJ.M. Tarascon, Physica B 165&166,1697 (1990).

92. Local Structure and Distorsions in Pure and DopedYBa2CujO7.6: X-Ray Absorption StudiesJ.B. Boyce, F. Bridges, and T. Claeson, in Supercon-ductivity and Applications (ed. by H.S. K wok et al),Plenum Press, N.Y. 1990, p 303.

93. Local Structure of BaBi,Pbi.,O3 Determined by X-ray Absorption SpectroscopyT. Claeson, J.B. Boyce, F. Bridges, T.H. Geballe, G.G.Li, and A.W. Sleight, Phys.Rcv.B44,6961 (1991).



Disordered Alloysand Bult High Tc Superconductors94. Critical magnetic field of disordered Zr-Cu alloys;

Density of states awl spin-orbit scattering timeA. Nordström, ö . Rapp and Z. Y. Liu, Phys. Rev. B.41,6708,1990.

95. TheMicrostnictureofaBi-Ca-Sr-Cu-OHighTc

Superconductor Produced by Rapid SolidificationPing Liu, M. Knutson, Liu Zhi Yi, E. Olsson and G.L.Dunlop, Supcrcond. Sci. Technol. 1(1989)254.

96. Study of the Effert of the Substitution of O by F.S,and Cl on the Superconductivity of YiBa^C 11307.7Liu Zhi Yi. M. Persson, and S. Eriksson. Z. Physik B74(1989)423.

97. Superconducting and Electronic Properties of theMetallic Glass System LarsSi^M, (M=Cr, Mn,Fe,Co,Ni,Cu,B,ALGaJn)Liu Zhi Yi, J.Kanski, ZJtiys.B. 22,495-499 (1989).

98. Negative magnetoresistance in an YBa2Cu3O7.fithin filmW. Holm, M. Andersson, Ö. Rapp, Z.G. Ivanov, andU. Engström, to be published, Physica B.

Single Charge Tunneling99. Single Electron Charging Effects in One-Dimen-

sional Arrays of Uttrasmall Tunnel JunctionsL. S. Kuzmin, P. Delsing, T. Claeson and K. K.Likharev, Phys. Rev. Lett. 62,2539 (1989).

100. Effect of High-Frequency Electrodynamic Envi-ronment on the Single Electron Tunneling inUtrasmall JunctionsP. Delsing, K. K. Likharev, L. S. Kuzmin and T.Claeson, Phys. Rev. Lett. 63,1180 (1989).

101. Time-Correlated Single-Electron Tunneling inOne-Dimensional Arrays of Ultrasmall TunnelJunctionsP. Delsing, K. K. Likharev, L. S. Kuzmin and T.Claeson, Phys. Rev. Lett. 63,1861 (1989).

Field effect transistor based on metal-insulator-artifkial grain boundary Josephson junction,Z.G. Ivanov, T. Claeson, E.A. Slepantsov, A.Y.Tzalcnchuk, and R.I. Shckhicr, in 1992 AppliedSuperconductivity Conference, edited by D. C.Larbalcsticr Chicago, USA, submitted to IEEETransactions on Superconductivity August 24-28,1992.

102. Two Fundamental Results from Low-Tempera-ture Experiments with One-Dimensional Arraysof Ultrasmall Tunnel Junctions.T. Clacson, P. Dclsing, L.S. Kuzmin, K.K. Likharcv,Proc. 3rd InL Symp. Foundations of QuantumMechanics. Tokyo. 1989, p.255.

103. Single Electron Charging Effects in Arrays ofUltra-Small Tunnel JunctionsL.S. Kuzmin, P. Delsing. T. Clacson, and K.K.Likharcv. Proc. 1989 InL Superconductivity Electron-ics Conf.. Tokyo, 1989, p. 549.

104. Single Electron Tunneling in Ultrasmall JunctionsT. Claeson, P. Delsing, L. Kuzmin. and K.K.Likharev, Proc. 5th Petra School of Physics, Septem-ber 1989.

105. 1-D Array implementation of the ResistivdyCoupled Single Electron Tunneling TransistorP. Dclsing, T. Claeson, K.K. Likharcv, and L.S.Kuzmin. IEEE Trans. Magn. 27,2581 (1)91).

106. Observation of Single ElectronTunneling OscillationsP. Delsing, K.K. Likharev, L.S. Kuzmin. and T.Claeson. Phys. Rev. B 42,7439,1990.

107. Single Electron Tunneling Oscillationsin One-Dimensional Arraysof Ultrasmall Tunnel unctionsP. Dclsing, T. Clacson, K.K. Likharcv, and L.S.Kuzmin. Physica B 165&166,929,1990.

108. Time-Correlated Single Electron TunnelingP. Delsing, T. Clacson, K.K. Likharcv, and L.S.Kuzmin. Proceedings of the 8lh European PhysicalSociety Conference (EPS-8), p. 667,1990.

109. Correlated Single Electron Tunneling inUltrasmall Tunnel JunctionsT. Clacson, P. Dclsing, D. Haviland, L. Kuzmin, andK.K. Likharev. To he published in Non-linearSuperconductive Electronics and Josephson Devices,Ed. by N.F. Pedcrson, M. Russo, A. Davidson, G.Coslabilc, and S. Pagano, Plenum. London, 1990.

110. Correlated Tunnel Events >n Arraysof Ultrasmall JunctionsT. Clacson and P. Delsing, to be published in Pro-ceedings of NATO Science Forum '90: Highlights ofthe Eighties and Future Prospects in CondensedMatter Physics, Plenum, New York, 1991.

111. Experimental Study of Submicron JosephsonTunnel Junctions with High-Ohmic Bias resistorsL.S. Kuzmin, D.B. Haviland, Yu.V. Nazarov, P.Dclsing, and T. Claeson, LT-1? Satellite Conf:Macroscopic Quantum Phenomena 1990, Brighton.

190 THE CENTRE FOR


112. Cooper-Pair Tunneling in Ultrasmall JunctionsAffected by Strong Quantum FluctuationsL.S. Kuzmin. YILV. Nazarov. D.B Haviland, P.Delsing, and T. Claeson, Phys. Rev. Letters, in prim.

Observations of the Noch Oscillations in anUHrasnuB Josephson JunctionL.S. Kuzmin and D.B. Haviland, Phys. Rev. Letters,subm.

114. Observations of the Bloch Oscillations HiUltrasmall Josephson JunctionsL.S. Kuzmin and D.B. Haviland, Proc.Nanostructures and Mesoscopic Systems, to be publ.

115. Observation of the Coulomb Blockade of CooperPair TuMeting in Single Josephson JunctionsD.B. Haviland, L.S. Kuzmin, P. Delsing, and T.Clacson, Europhysks Letters, 16,103 (1991).

116. One-Dimensional Arraysof Small Tunnel JunctionsP. Delsing, in Single Charge Tunneling (ed. by H.Grabcrt and M. Devorei, Plenum Press, N.Y.), p.249,1992.

117. New Results on SET-Oscillations inOne-Dimensional Arrays of Tunnel JunctionsP. Delsing, D. Haviland, T. Claeson, K.K. Likharcv,and Korotkov, in Single Electron Tunneling andMesoscopic Devices, cd. by H. Koch and H. Liibbig,p. 97 (Springer, Berlin 1992).

118. Single Electron Tunneling Oscillations in One-Dimensional Arrays of Ultrasmall Tunnel Junc-tions. P.Dclsing, T.CIacson JC.K.Likharcv, andL.S.Kuzmin. Proc. 19lh Int. Conf. Low Temp.Physics (LT-19), Physica B 165&166,929 (1990).

119. Coulomb Blockade and Incoherent Tunneling ofCooper-pairs in Ultrasmall Junctions Affected byStrong Quantum Fluctuations. L.S.Kuzmin,Yu.V.Nazarov, D.Haviland, P.Dclsing, andT.Clacson. Phys. Rev. Lett. 67,1161 (1991) In:"Single Electron Tunneling and Mesoscopic De-vices" , ed. by H.Koch and H.Liibbig, p.97 (Springer,Berlin 1992)

120. Comparison of the Transition to the InsulatingState in Two-Dimensional and One-DimensionalArrays of Ultrasmall Tunnel Junctions. P.Dclsing,Chen Chiidong, D.B.Haviland, and T.Clacson. In:Single Electron Tunneling and Mesoscopic Devices,cd. by H.Koch and H.LUbbig, p.137 (Springer, Berlin1992)

121. Experimental Evidence for the Coulomb Blockadeof Cooper Pair TunneKng and Bloch Osculationsin Single Josephson Junctions. D.Haviland.L.S.Kuzmin, P.Deking. K.K.Likharev. andT.CIaeson. Z Phys. B 85,339 (1991)

122. Experimental Investigation of Two-DimrnsionalArrays of Ultrasmall Josephson junctions. ChenChiidong. P.Dclsing, D.B.Haviland, and T.Clacson.Hclv. Phys. Acta, 65.406 (1992)

123. Single Charge Tunnrting-Time Correlation ofTunnel Events. T.CIaeson. P.Dclsing. D.Haviland,L.S.Kuzmin, K.K.Likharev, and Yu.V.Nazarov. In:Supercon. Sci. Tnech, p.393 IOP (1991)

124. Single Electron Turnsole and Pump Devices UsingLong Arrays of SmaH Junctions. P.Dclsing andT.Clacson. Physica Scripla Vol. T42,177 (1992).

125. Experimental Investigation of Two-DimensionalArrays of Ultrasmall Josephson junctions.C.D.Chen, P.Dclsing, D.B.Haviland, and T.CIaeson.Physica Scripta Vol. T42,182 (1992).

126. From Josephson to Single Charge Tunneling.CD.Chcn, T.Clacson, P.Delsing, Y.Harada,D.Haviland, L.S.Kuzmin, and Yu.Pashkin. Proc. Int.Conf. on Macroscopic Quantum Phenomena p.55(1993).

127. Single Charge Electronics Based on UltrasmallTunnel junctions - Comparison with JosephsonElectronics. T.CIaeson, P.Dclsing, D.Haviland,L.S.Kuzmin, and Yu.Pashkin. Esprit Conf. Brussels1992.

128. Thermal Activation and Injection of ChargeSolitons In Two-dimensional Arryas of SmallJosephson Junctions. P.Dclsing, C.D.Chen,D.B.Haviland, Y.Harada, and T.Clacson. Submittedto: The 20ui ImXonf. on Low Temp. Physics, LT-20,(1993).

129. A New Temperature Sensor in Low-temperatureComposite Bolometers for Detection of NuclearParticles. F Delsing, C.D.Chen, T.CIaeson,P.Davidsson, B Jonson, M.Lindroos, S.Norrman,G.Nyman, and S.Qutaishat. Submitted to: The 20thInt.Conf. on Low Temp. Physics, LT-20, (1993).

130. Vortex Mobility in Two-dimensional Arrays ofSmall Josephson Junctions. C.D.Chen, P.Dclsing,D.B.Haviland, Y.Harada, and T.Clacson. Submittedto: The 20th IntConf. on Low Temp. Physics, LT-20,(1993).



131. MagnelkFhn and Gate Voltage Dependence ofthr Current m a Superconducting Loop of UKra-sauH TMMC! Junctions. Y.Harada, D.B.Haviland,CD.Chen, RDdsing, and T.Claeson. Submitted lo:The ?0ih IntConf. on Low Temp. Physics, LT-20,(1993).

132. 2e Periodic Modulation of tke I-VcurveofaCurrent Biased Superconducting Transistor.YiLPasNun, D.B.Haviland, L.S JCuzmin, C.D.Chen.PDelsing, and T.Claeson. Submitted to: The 20thIntCcnf. on Low Temp. Physics. LT-20, (1993).

Mesoscopic Transport Phenomena,Scanning Probe Microscopy

133. Electron Transport ål Mesoscopic Conductorswith Superconducting ContactsV. Petrashov, V. Antonov and M. Persson, Phys.ScripiaT42(1992).

134. Electron phase memory effects in normal nwtalrings with superconducting mirrorsV. Petrashov, V. Antonov, P. Dclsing, and T.Claeson, Phys.Rev.Lcti, 70,347 (1993).

135. Nonlinear Phase Memory Effects in MesoscopicRings With Superconducting "Mirrors".VXPetrashov, V.N Antonov, RDelsing, andT.Claeson. Submitted to: The 20th IntXTonf. on LowTemp. Physics, LT-20, (1993).

136. Electric field effects and screening in mesoscopicBismuth wiresV.T. Petrashov and V.M. Anionov and B. Nilsson, J.Phys.: Condens. Matter, No.3,9705-9711,1991.

137. A Resistive HEMT-mixer with Very Low LO-Power Requirements and Low IntermodulatioZirath H., Rorsman N.,, 21st EuMC, 1469 -1474,1991

138. Nd:YAG Laser Machining with Multilevel ResistKinoformsMats Ekberg, Michael Larsson, Aldo Bolie andSverker Hard,", SPIE Proceedings of current develop-ment in optical design and optical engineering,Vol.1527,1991

139. Proximity-compensated kinoforms directlywritten by electron-beam lithographyM. Ekberg, M. Larsson and S. Hård,, SPIE Proceed-ings of Workshop on Digital Holography, Vol. 1718,1992

140. IVoxiniity-coniDensaltdkinofonDS directlywritten by etectron-beat lithographyM. Ekberg. M. Larsson and S. Hård.. SPIE Proceed-ings of Holographies Inicmationa] 92, Vol.1732.1992.

141. TOverkuagav högeffektiva fashongram,KnoformerM. Ekberg, M.Larsson and S. Hard,".Raduvetensteptig konferens, RVK 90,1990.

142. High efficiency computer generated diffractiveoptical elementsF. Nikolajcff, M. Ekberg, M. Larsson and S. Härd,,Radiovetenskaplig konferens. RVK 93,1993.

143. Fabrication of ultra high quality vertical struc-tures in Ga AsMats Hagberg,, SPIE Micro'92, Vol.1672,1992.

144. GaAs/AIGaAs corner reflector laser for mono-lithic integrationMats Hagberg,, European Conference on OpticalCommunications, September, 1992.

145. Mkroengineered Material Surfaces for StudyingCellular Responses to Controlled Surface Rough-ness and CompositionJ.M. Gold,, BIOINTERACTIONS, 1993.

146. Two Methods of Experimental Evaluation ofLong-range Proximity Function Components in E-beam LithographyAL.Bogdanov and A. Polyakov,, The 37th Sympo-sium on Electron, Ion and Photon Beams, 1993.

147. Quantum Interference Effects in Percolated MetalNetworksM.E.Gcrshcnson, P.M. Echtcmach, H.M. Bo/lcr,A.L. Bogdanov, B.Nilsson,, International Conferenceon Low Temperature Physics, 1993.

Microelectronics and Other StudiesBased on Nanometer Fabrication

148. Site-specific adhesion of S. epidermidis in Ti-AI-Vmetal systemsGabriel, B. L, Gold, J., Gristina, A. G., Kascmo, B.,Lausmaa, J., Mroczck, C , Myrvik, Q. N., & Nilsson,B., in Surfaces in Biomaterials Symposium,Minneapolis, USA, 1992) 126-130.

149. Scanning Tunneling Microscopy of Laser Depos-ited TI2Ba2CaCu2Oji Thin FilmsErts, D., Ivanov, Z. G., Johansson, L. G., Olin, H., &Clacson, T., to be submitted, 1993.

192 THE CENTRE FOR


ISO. STM studies of Single Electro* Tunneling Effects» ThB^CaCöiOg Th« Films at 300 KEns, D., Ivanov. Z. G., Johansson. L. G., Oiin. H., &

Claeson, T., to be submitted. 1993.

151. Mriti i Manufactured byPhase HotoejiElectron Beaai LithographyMais Ekberg. Michael Larsson and Sverker Härd,Optics Letters. Vol.15. No. 10, 568-569. May, 1990.

152. Nd:YAG Laser Machining whh Multilevel ResistKinofbnasMais Ekberg. Michael Larsson, AMo Bolie andSverker Hard., Applied Optics, Vol. 30, No. 25.3604-3606, September, 1991.

153. Multilevel gratia*, arraytared by elMats Ekberg, Michael Larsson, Sverker Hård, JariTimmen, Mohammad R. Taghizadeh, JanWcsterhoJm, Antti Vasara. Optics Communications,Vol.88, No.l,37-41,March, 1992.

154. Proximity-Compensated Blazed TransmissionGrating Manufacture with Direct- WritingElectron-Beam LithographyM. Ekberg, F. Nikotajeff, M. Larsson and S. Härd,Accepted for publication in Applied Optics, 1993.

155. Successive-Development Optimization of ResistKinofbrms Manufactured with Direct WriteElectron-Beam LithographyM. Ekberg, F. Nikolajcff, M. Larsson and S. Härd,Accepted for publication in Applied Optics, 1993.

156. A New Method for Determination of the Peak-velocity in Epitaxial Semiconductor Sructures byDC-measurements on MkrobridgesStrupinski W., Zirath H., Grönquist H., Rorsman N.,Appl. Phys Letters, Vol.59,3151-3153,1991.

157. A New Empirical Nonlinear Model for HEMTand MESFET DevicesAngclov I., Zirath H., Rorsman N., submitted toMTT.

158. A Millimeterwave SubharmonUally PumpedResistive Mixer Based on Heterostructure FieldEffect Transistor TechnologyZirath H., Angclov I., Rorsman N., IEEE-MTT-S,1992.

159. A New Empirical Nonlinear Modelfor HEMT-devicesAngclov I., Zirath H., Rorsman N., accepted forIEEE-MTT-S, 1992.

160. A Balanced Millimeter Wave Doubter Based onPseudomorphic HEMT'sAngclov I., Zirath H., Rorsman N.. Granqvist H..accepted for IEEE-MTT-S. 1992.

161. Fabrication of uttrahigh quality vertical facets inGaAs using pattern corrected electron beamlithographyM. Hagberg, B. Jonsson, and A. Larsson, J. Vac. Sci.Technol. B, Vol.10, No.5,2243-2250, Sep/Oct, 1992.

162. Single-ended output GaAs/AIGaAs single quan-tum well laser with a dry-etched corner reflectorM. Hagberg, A. Larsson, and S. T. Eng.,, Appl. Phys,Lett. Vol.56, No.20,1934-1936, May, 1990.

163. Investigation on the Spectral Characteristics ofDFB-Lasers with Different Grating Configurationmade by Electron Beam LithographyT. Kjellberg, S Nilsson, T. Klinga, B. Broberg and R.Schatz,, Journal of Lightwave Technology, volumeII, August, 1993.

164. Model Based on Trap-assisted Tunneling for Two-level Current Fluctuation in SubmicrometerMetal-Silkondioxide-Silicon DiodeM. O. Andersson and Z. Xiao and S. Norrman and O.Engström,, Physical Review B, Vol.41, No.14,9836- 9842, May, 1990.

165. Phase relaxation in One-dimesional Metal FilmsP.M. Echtcmach, M.E. Gcrshenson, H.M. Bozlcr,A.L. Bogdanov, B.Nilsson, Nyquist, Phys RevLetters B, submitted.

166. Quantum Interference Effects in One-dimensionalGold FilmsP.M. Echtemach, M.E. Gcrshcnson, H.M. Bo/.lcr,A.L. Bogdanov, B.Nilsson, Physics Review B,submitted.

167. Fine Undercut Control in Bilayer PMMA-P(MMA-MAA) resist system for E- beam Lithog-raphy with Submicron ResolutionAlcxci L. Bogdanov, Eva Karin Andersson, SPIEElectron-Beam, X-Ray, and Ion-BeamSubmicrometer Lithographies for Manufacturing,Vol.1465,1991, p 324-329.

168. Selective Chemically Assisted Ion Beam F.tchinr, ofSi, Polysilicon and SiO2 Using Ni-Cr Mask andCI2Z. Xiao and B. Nilsson and P. Svedberg, Journal ofElectrochemical Society, Vol.137, No.5,1579-1581,May, 1990



149. Good Selectivity Betweea a Ni-Cr mask and andGaAs and AIGaAs by Chemical Assisted UrnBeam Etching with CB GasZ. Xiao and B. Nilsson, G ", Journal ofElectrochemical Society, Vol.138.No.lO. 3092-3095,October, 1991.

Reviews170. H ^ Temperature Superconductor Assessment

Study for Spaceborn Sensor ApplicationsG. Brorsson, T. Clacson, M. Danenid, J. Edstam, Z.Ivanov. P Å Nilsson U. Helmcrsson, S. Rudncr, S.Dahl-Poerscn, T. Freltofl, J. Hyktoft, P. Vase. MXLcvinscn, J.B. Hansen, C.S. Jacobscn. and N.F.Pcdcrsen, ESTEC 8007/88/NL/PB(SC).

171. Superconducting Detectors Tor mm andSub-mm WavesD. Winklcr, Z. Ivanov, and T. Clacson, in Supercon-ducting Technology: Ten Case Studies (cd. by K.Fossheim) World Scientific, Singapore, p. 51 -86(1591).

172. Single ElectronicsK K Likharcv and T Clacson, Scientific American,June 1992, p 80-85.

173. A Pilot Study for High Temperature Supercon-ducting Gravity GradiometersC.S. Jacobscn, A. Kuhle, J. Mygind, N.F. Pcderscn,J.B. Hanscn, T. Frcltoft, Y. Shen, P. Vase, T.Clacson, Z. Ivanov, P.Å. Nilsson, J. Flokstra, H.Hilgenkamp, and E. Annandillo, ESA/ESTECWorkshop on Space Applications or High Tempera-ture Superconductors, ESTEC, Höland, April 27-28,1993

Theses174. Single Electron Tunneling in Ultrasmall Tunnel

JunctionsPer Dclsing, Ph. D. Thesis, Dcpt. Physics, ChalmersUniv. Tcchn., Gothenburg, 1990.

175. Thin Films and Optical Detectors made of

Martin Danerud, Lie. Thesis, Dcpt. Physics,Chalmers Univ. Tcchn., Gothenburg, 1991.

176. Laser Deposited Thin Films of the High Tempera-ture Superconductors YBaCuO and BiSrCaCuOGöran Brorsson, Lic. Thesis, Dcpt. Physics, ChalmersUniv. Techn., Gothenburg, 1991.

177. Tim rlfcas of YBazCujOr Deposited by Co-Evaporatioa, Josephson Junction, and DC-SQL'IDsPer-Åke Nilsson, Lic. Thesis, Dcpt Physics.Chalmers Univ. Tcchn.. Gothenburg, 1991.

178. Scanning Probe Microscopy,Design and ApplicationsH. Olin. (1993) Ph. D. Thesis, Chalmers Umv. ofTech.

179. Theoretical and Experimental Studiesof the Flux-Flow Type Josephson OscwatorYongming Zhang, l ie. Thesis, Dcpt. Physics,Chalmers Univ. Tcchn., Gothenburg. 1991.

180. Lumped Arrays of Josephson Junction OsctBatorsJonas Edaam, Lie. Thesis, Dcpt. Physics, ChalmersUniv. Tcchn., Gothenburg, 1992.

181. Symmetric Scanning Tunneling Microscopes forUltra High Vacuum and Very Low TemperaturesPer Davidsson, Lie. Thesis, Dcpt. Physics, ChalmersUniv. Tcchn., Gothenburg, 1992.

Scanning Probe Microscopy182. Design of a Scanning Probe Microscope

Olin, H., Mcas. Sci. Tech., 1992, submitted.

183. Scanning Tunneling Microscopy of Laser Depos-ited YBCO Thin FilmsOlin, H., Brorsson, G., Davidsson, P., Ivanov, Z. G.,Nilsson, P. Å., & Clacson, T., Ultramicroscopy, 42-44,1992,734-737.

184. Design and Operation of a Low TemperatureScanning Tunneling Microscope Suitable forOperation below IKDavidsson, P., Olin, H., Persson, M., & Pchrson, S.,

Uliramicroscopy, 42-44,1992,1470-1475.

185. Movement of Scattering Centers in a PointContact Induced by a Scanning TunnelingMicroscopeKubatkin, S. E., & Olin, H., to be publ.

186. Scanning Tunneling Microscopy of OxidizedTitanium Surfaces in AirOlin, H., Aronsson, B. O., Kascmo, B., Lausmaa, J.,& Rodahl, INI, Ultramicroscopy, 4244,1992,567-571.

187. Microfabricated nanopipettesOlin, H., Stenberg, M., Stcmmc, G., & Olsson, E,Mcas. Sci. Tech., 1992, submitted.

194 THE CENTRE FOR


IM. Sto*pecaVadlMsiNorS.CFtilcrButis»Ti-AI-Vawtal systemsGabriel, B. L., GoU, J., Gristina, A. G., Kascmo, B..Lausmaa. J.. Hancr. C . & Myrvik. Q. N.. submitted,1992.

189. Movenwat of Scattering Centers in a Po«tCotact Indnccd by a Scaaaiag TaaataTag Micro-scopcKubadun, S. E., Ota», R, Davidsson. P., Danilov. A.

V., &. Cfaeson, T., Physka B. submitted. 1993.

type DsapcrcoadactorsasiBg the very lowteMseratarc fancKag McroscopeDavidsson, P., & d in , H., Physka B, submitted,1993.

191. Atomic farce microscopy and tnwsmissioBelectron Microscopy of early stages of growth ofYBa^wjO^ thin fans on (001) Y-ZrO*SubstratesAlan», J. A.. Brorsson, G., Olin, H.. Olsson, E., &.

Clacson, T, SCANDEM 93,1993.

192. Early stages of growth of YBazCu3O74hign.Tc

thin finns on (001) Y-ZKh Alarco, J. A., Brorsson,G., Olin, H., Olsson, E., & Claeson, T., to be submit-ted, 1993.


Condensed Matter Theory

Research SummaryThe research of the group involves three majordirections with many interconnections: (i) Super-conductors and high-temperature superconductiv-ity, (ii) atoms, molecules and solids in strong radia-tion fields, and (iii) electronic structure and excita-tion spectra of clusters and solids. Over the last twoyears focus has been on problems involving super-conductors or clusters, or both. During this periodtwo major projects have been started: One project isto calculate the electron dynamics of small clustersand molecules for interpretation of photoabsoiptionand photoelectron emission spectra. This gives in-formation about single-electron and collective be-haviour and about geometric and vibrational struc-ture. Another project is to address some centralissues in the field of high-temperature superconduc-tivity, HTSC. One such issue involves calculation ofoptical properties and Raman spectra to test theoreti-cal models for the normal and superconductingproperties of HTSC. Another issue concerns variousmanifestations of the Josephson effect in weak linksand grain boundary junctions in thin films of high-temperature superconductors.

The work on superconductivity is partly donewithin the framework of the Consortium on Super-conducting Materials, and in collaborations withscientists from Russia and Ukraine, while the clusterwork is done in collaboration with American andCroatian scientists.

At the moment we are involved in some rather hottopics. One topic involves the dynamics of theJosephson current in a weak link tunnel junctionirradiated by intense electromagnetic radiation. Thiskind of work might one day lead to the develpmentof a superconducting transistor with an optical gate.Another hot topic involves many-electron dynamicsin Q o and Ba-Qn: Our recent results show bothcollective effects and multiple-scattering interfer-ence effects in Ba-Qn, La-Qo and related systems,and the method has a great potential for furtherdevelopment and as a testing ground for many-electron theory.

AddressDepartment of Theoretical Physics and MechanicsChalmers University of TechnologyS-412 % Göteborg, SwedenPhone+46 317721000Fax 446 31772 3204

StaffSenior Members:Göran Wendin docentBo Wästberg tekn.dr.Sergey Rashkeev Ph.D.

Graduate Students:Magnus Hurd civ.ing.Jarek Luberek civ.ing.

Secretary:Jane Johansson

Major Instrumentation» Sun work stations• Macintosh personal computers

Major Reids of ResearchA: Superconductors and High-Temperature

Superconductivityparticipants: Göran Wendin, Magnus Hurd,Sergey Rashkeev, Alex Bratkovsky,collaborators: Zeljko Crljen, Robert Shekhter,Vitaly Shumeiko

B: Atoms, Molecules and Solids in Strong Radia-tion Fieldsparticipants: Göran Wendincollaborators: Peter Johansson, Lars Jönsson,Vitaly Shumeiko

196 THE CENTRE FOR

CONDENSED MATTER THEORY

C: Electronic Structure and Excitation Spectra ofOusters and Solidsparticipants: Göran Wendin, Jarek Luberek,Bo Wästberg, Alex Bratkovskycollaborators: Zeljko Crljen, Zachary H.Levine

Research ProjectsA: Superconductors and High-

Temperature Superconductivity

A l : Optical Properties of High-TemperatureSuperconductors

This project began with an analysis of spectroscopicresultsforHTSC[l]and continued with calculationsof photoabsorption spectra and optical conductivityfor YBaiCuiOj within a model which describeswell the electron dynamics of the atomic cores, butnot of the vaience electrons [2,3,14]. This is onereason why the cluster work was started, to describemolecular effects in photoionization arising withine.g. the CuO and BaO units [9,24,26]. At present weare focussing on the low-frequency (0-1 eV) spec-trum of HTSC, studying optical conductivity andelectronic Raman scattering within the frameworkof Eliashberg theory and beyond, including effectsof stro-g inelastic scattering bandstructurc [19]. Weare also working in general analysis and survey of thefield [20].

A2: Transport Properties Superconductors InExternal Fields

The first project started as a Swedish-Soviet collabo-ration [5] and soon developed into a variety ofprojects, involving tunneling [10,11], and effects ofirradiation with light [10,12,13,18,23,25]. Of par-ticular interest is our present work on the time-dependence of the Josephson current in a weak linktunnel junction irradiated by intense electromag-netic radiation [25]. We intend to develop this workinto an important collaboration with experimentalistsand to investigate various possibilities to influencesuperconducting electronics with electromagneticradiation. This may find applications in sensors andoptoelectronic components.

B: Atoms, Molecules and Solids inStrong Radiation Fields

Fora long time we have been heavily involved in thefield of interaction of atoms and quantum-well struc-tures with intense laser radiation. This work recentlyresulted in two dissertations and a number of re-search papers [6-8,15], and is now influencing ourpresent work in many ways, in applications to super-conductors [13,18] and superconducting mesoscopicstructures like weak links and junctions [25].

6000

5000

4000

3000

2000

1000

-1000

-2000

BaCn (N=232+5t>)

- t t t f t t t t t t t t3s2f2d2pll2s Ik 5pij li Ih5slglfldlpls

10 15 20 25photon energy (eV)

30 35 40

Figure 1The calculated photo-absorption cross section fora jellium shell with N=232(Ceo) (dashed line) and for aBa atom (Z=56) embeddedin a jellium shell withN=232 (BaCeo) (solid line)using the TDLDA method. Atthe bottom of the figure, thethresholds for photo-emission from the variuosoccupied shells of a Ba andC6o have been marked witharrows.



C: Electronic Structure and ExcitationSpectra of Clusters and Solids

This project includes a variety of problems within

Computational Physics, (i) One-center cluster mod-

els, calculating the electronic dynamics within the

time-dependent local-density approximation

(TDLDA) for CuOx, BaOx [9,24], (ii) electronic

excitations in heavy many-electron atoms embed-

ded in electron gas, describing metals and impurites

in metals [21], (iii) spherical cluster models, in

particular for Qo and Ba, La-Qo within TDLDA

[22], and (iv) electronic structure and excitations in

magnetic alloys and disordered systems (supercell

cluster calculations) [17].

PublicationsPh.D. DissertationsLais Jönsson, "Diagrammatic many-body theory for atoms

in high-intensity laser fields", September 18 1990

Peter Johansson, "Theory of inelastic tunneling - applica-tions to double barrier structures and scanningtunneling microscopes", June 61991

Licentiate DissertationsOla Nyqvist, "Screening effects in layered compounds:

Applications to semiconductor interfaces and high-Tc",June 101991

DipkMnaWorttThomas Mattsson, "Resonant inverse photoemission via

plasmons", July 1990

Reports and articles1. "Spectroscopic views of high-Tc superconductors"., G.

Wendin, in "Physics of Low-Dimensional Systems",Ed. S. Lundqvist Physica Scripta 122,1989,31

2. "Calculation of photoionization cross sections of high-Tc superconductors", G. Wendin and Z. Crljen,Phvsica C 162-164.1989,1327

3. "Optical conductivity and photoemission spectra formodels of high-Tc superconductors", G. Wendin and Z.Crljen, in Electronic Properties of High-Tc Supercon-ductors and Related Compounds, edited by H.Kuzmany, M. Mchring and J. Fink, Springer Scries inSolid State Sciences, vol 99 (Springer Verlag, Berlin,1990), 147-151

4. "Theoretical investigation of low-energy electron-impact excitation and ionzation of rare-earth andactinidc solids". H.R. Moscr, and G. Wendin, Phys.Rev. B 44,1991,6044

5. "Transport of local pairs in the electric Field andfrequency dependence of the oxide conductivity.", R.I.Shekhter, G. Wendin and O. Kulik, Phys. Rev. B 44,1991,10215

6. "Diagrammatic many-body theory for atoms in high-intensity laser fields. Part I"., L. Jönsson and G.Wendin, J. Opt. Soc. Am. B 2,1992,627

40

35

30

25

20

15

10

5

n

_

-

-

-

-

-

80

i

a)

4d

90

1

I

!

* ji

100

7\~T 1 1

/ / \

i VA \i v/ \ \1 \V

Ki i i—

110 120 130

photon energy (eV)

i i

B a C 60

5 3 + C60cC60

•4d-f(BaCJ-

-

-t 4 "-t

140 150 16

Figure 2Photoabsorption crosssection cross sections ofBa and BaC6o showing the4d-f giant dipole resonance.The cross sections werecalculated using the TDLDAmethod for a Ba atom andfor Ba in a jellium shell(ISN288). The BaC6o crosssection is compared to thecross section of the N=232jellium shell model for C6o.the Ba atom + the N=232jellium shell cross sectionand thge 4d-f cross sectionof BaC6o-

198 THE CENTRE FOR


7. "Diagrammatic many-body theory for atoms in high-intensity laser fields. Part II". L. Jönsson, J. Opt. Soc.Am. B 2,1992,646

8. 'Tunneling through a double-barrier structure irradi-ated by infrared radiation", P. Johansson and G.Wendin, Phys. Rev. B 46., 1992,1451

9. "Calculation of electronic excitation and ionizationprocesses in high-Tc superconductors "., Z. Crljen, G.Wendin and Z.H. Levine, in Electronic Properties ofHigh-Tc, Superconductors and Related Compounds,edited by H. Kuzmany, M. Mehring and J. Fink,Springer Series in Solid State Sciences, (SpringerVerlag, Berlin, 1992), in press

10. "Investigation of tunneling, linear and non-linearoptical properties of negativc-U local pair models forhigh-Tc superconductors"., Z. Crljen, M. Hurd, L.Jönsson, R.I. Shekhter, V. Shumeiko and G. Wendin,in Electronic Properties of High-Tc Superconductorsand Related Compounds, edited by H. Kuzmany, M.Mehring and J. Fink, Springer Series in Solid State,Sciences, (Springer Verlag, Berlin, 1992), in press.

11. "Single-electron tunneling into randomly distributeddouble-electron slates: linear voltage and temperaturedependences of the conductance"., M. Hurd, R.I.Shekhter and G. Wendin: Phys. Rev. B 46., 1992,8527.

12. "Optical spectroscopy of localized states in metallicoxides"., R.I. Shekhter, Z. Crljen and G. Wendin,PhysicaScr.Ti2,1992,76.

13. "Infrared threshold absorption in strongly correlatedtwo-band super-conductors"., V. Shumeiko, L.Jönsson, R. Shekhtcrand G. Wendin, Physica Scr.T42,1992,83.

14. "Calculation of optical conductivity and electronenergy loss spectra for YBa2Cu3O7 in the 10-160 eVrange"., G. Wendin and Z. Crljen, Z. Phys. B, in press

15. "Exact diagrammatic solution of a three-level systemin a high-intensity laser field"., L. Jönsson, J. Phys. B21,1992,5085

16. "Oxygen diffusion and dynamical disorder in high-Tc,superconductors: low frequency noise in superconduct-ing tunnel junctions"., R.I. Shekhter, A.M. Zagoskinand G. Wendin, Z. Phys. B, in press

17. "Supercell spin-polarized and full-potential LMTOcalculations of the electronic structure of the glassymetal Ni2B", A.M. Bratkovsky, SJM. Rashkeev, A.V.Smirnov and G. Wendin, 8th Int. conf. on Liquid andAmorphous Metals, Vienna, 1992. Full paper submit-ted to Phys. Rev. B.

18. "Effects of ne^ative-U correlation on superconductingand optical properties of two-band superconductors".,V. Shumeiko, L. Jönsson, R. Shekhter and G.Wendin,submitted to Phys. Rev. B .

19. "Electronic Raman continuum for YBa^ujOz^:Effects of inelastic scattering and interband transi-tions"., S.N. Rashkeev and G. Wendin, submitted toPhys. Rev. Lett

20. "Different views of optical conductivity of high-Tcsuperconductors". G. Wendin, invited paper, to besubmitted to Mod Phys. Leu B

21. "Calculation of photoionization cross sections of Ba,La and Th atoms embedded in electron gas: Effects ofhybridization on giant dipolc rcsonances".G. Wendinoch J. Luberek, to be submitted to Phys. Rev. Leu.

22. "Many-electron effects in models of Qo and BaXa-C(5o: Collective response and molecular effects inoptical conductivity and photoionization.", G. Wendinand B. Wästberg, to be submitted to Phys. Rev. Leu.

23. "Anisotropy of infrared optical absorption in layeredsuperconductors'W. Shumeiko and G. Wendin, to besubmitted to Phys. Rev. B

24. "Collective response and molecular effects inphotoionization of a BaQ2 cluster. A one-centerTDLDA calculation"., Z. Crljen, J. Luberek, G.Wendin and Z. H. Levine, to be submitted to Phys.Rcv.

25. "Optical nutation of Josephson current in a tunnelcontact"., V. Shumeiko, G. Wendin and E. Bratus', tobe submitted to Phys. Rev. Lett.

26. "Calculation of electronic excitation spectra of copperoxide clusters". Yu-juin Wang, G. Wendin, M.D.Newton and J.W. Davenport, to be submitted to Phys.Rev. B.


CeramicsSwedish Ceramic Institute, SCI 202See also under Microscopy and Microanafysis



Research SummaryThe Swedish Ceramic Institute (SCI) is a co-operativeresearch institute within the group of IndustrialResearch Institutes of Sweden (IRIS). SCI providessupport to manufacturers of ceramics by carryingoutapplied research within the area of ceramic process-ing techniques such as powder preparation, shapeforming and sintering. It also provides support tousers of ceramics by evaluation of properties ofmaterials, selection of materials, manufacturing ofprototypes and failure analysis. The number of in-dustrial members in SCI is around 25.

About 50 % of the R & D at SCI is long-termresearch performed within the framework programfor engineering ceramics and traditional ceramics.The program consists of a number of individualprojects that often are linked together, they have aduration time of 3 years and are jointly planned andsteered by SCI and the program committees, one foreach area, representing the member companies ofSCI. Connected to each individual project within theprogram isaproject committee which meets twice orthree times every year. In addition to the steeringfunction these committees also have a very impor-tant role to transfer technology from SCI to theindustry. Most of the projects within the frameworkprogram have a general aim and are of interest to amajority of the members and, hence, the results areavailable to all member companies of SCI. How-ever, in certain areas there are only a few companiesinterested in a specific project and then this project isfinanced and is open only for some of the membercompanies. The framework programs are funded 60% from industry and 40 % from the Swedish Na-tional Board for Industrial and Technical Develop-ment (Nutek).

As a complement to the framework program SCIalso carries out separate projects for individual com-panies or a consortium of companies. The totalextent of such separate projects is about 30 % of theentire R & D at SCI. Most of these projects are alsoof a long-term nature and are steered in the same wayas the projects within the framework program. The

separate projects are funded from industry and gov-ernment sources in different proportions but 50 %from industry and 50 % public funding are common.

The remaining more development-oriented workat SCI is composed of different services to theindustry, from small analysing tasks to other typi-cally short- term projects, altogether about 20 % ofthe entire R & D. These activities are funded by theindustry.

Processing is the key issue in producing ceramiccomponentsatreasonable prices. SCI has four groupsworking on Powder pressing & Injection moulding,Slip casting, Sintering and Evaluation of propertiesrespectively. All the main materials systems withinthe structural ceramics area are represented withinSCI such as alumina, silicon carbide, silicon nitride,zirconia, mullite, composites with these matricesand fibers such as silicon carbide, carbon, aluminaand silicon carbide whiskers.

SCI has an extensive co-operation with manymaterials-oriented groups and departments atChalmers University of Technology such as theElectron Microscopy group - Physics, EngineeringMetals, Polymeric Materials, Chemical Technology,Polymer Technology, Inorganic Chemistry, Physi-cal Chemistry, Building Materials.

AddressSwedish Ceramic Institute, SCIBox 5403S-402 29 Göteborg, SwedenPhone+ 46 31772 0500Fax + 4631 1853 80

Staff

R. CarlssonE. CarlströmS. KarlssonE. LidenR. PompeK. Rundgren

professor, VDtekn.dr.civ.ing.civ.ing.docentni.dr.

202 THE CENTRE FOR

SWEDISH CERAMIC INSTITUTE, SCI

Graduate Students:J. BrandtL. KahlmanA. KristofferssonK. Lindqvist0 . LyckfeldtB. Nyberg

Technical Staff:C. BemmL. EklundE. FreiholtzH. LeanderssonR. SalomonssonM. Sjöstedt

Secretaries:U-B. JigholmM. Jansson

civ.ing.civ.ing.civ.ing.civ.ing.civ.ing.civ.ing.

ing.ing.lab.assistanting.lab.assistanting.

Major InstrumentationInstrumentation tor analysisof chemical composition etc:• Jeol, JSM-5300 Scanning Electron Microscope

(with Tracer X-ray analyser)• Jeol, JXA-8600 Electron microprobe X-ray

analyser• Kontron, IBAS Image analysing system• Leco, Carbon analyser• Masstorr, Mass spectrometer• Philips, X-Ray diffractometer

Instrumentation for mechanical testing:• Cerama, Hydraulic tensile testing machine• Åbo Akademi, Fibre tensile testing machine• Zwick, Universal mechanical testing machine• Controls, Compressive testing machine• SCI, Stepped temperature stress rupture testing

machine• Briiel & Kjaer, Modulus of elasticity tester• Zwick, Microhardness tester• Zwick, Gypsum hardness tester• Zwick, Impact testing machine• Tonindustrie, Impact testing machine for

porcelain plates• SCI, Friction and wear testing machine• SCI, Glaze wear testing machine

Instrumentation for machining:• Profila, Surface grinder• Different cutting machines and sample prepa-

ration equipment

Instrumentation for manufacturingof ceramics:• Centorr, Graphite furnace, 2100°C• Pfeiffer, Graphite furnace, 2200°C• Ruhstrat, Graphite furnace, 2500°C• Different fast furnaces for maximum 1700°C• Different furnaces for maximum 1500-1700°C• Loomis, Cold isostatic press• Brabender, Z-blade mixer• Peltsman, Low pressure injection moulding

machine• Troester, Roller mill/Calander• Tape casting machine for continuous casting of

thin layers in organic media or water• Netzsch, Pressure slip casting machine• Biichi, Mini spray dryer• Biichi, Thermal evaporator• Leybold, Freeze dryer• Cole-Parmer, Ultrasonic homogeniser• Feutron, Climate chamber• Different mills, sieves and presses

Instrumentation for process analysis:• Contraves, Viscometer• Rheometer for constant stress analysis• Repab, Zeta potential meter• Micromeritics, Particel size analyser• Micromeritics, Specific surface area analyser• Micromeritics, Mercury porosimeter• SG, Equipment for analysis of the dewaxing

of polymers• Mettler, Thermobalance and Differential

Thermal Analyser, 1600°C• Harrop, Thermobalance, 1600°C• Harrop, Differential Thermal Analyser,

1600°C• Harrop, Dilatometer, 1600°C



Major Reids of ResearchA: Processing of Engineering Ceramics

participants: J. Brandt, E. Carlström, S.Karlsson, A. Kristoffersson, E. Liden, K.Lindqvist, O. Lyckfeldt, B. Nyberg, R.Pcmpe, K. Rundgrencollaborators: Powder Technology CenterGöteborg, Engineering Metals, PolymericMaterials, Physics and other departments atChalmers University of Technology, theCenter for Ceramic Research, Rutgers Uni-versity, NJ

B: Wear Resistant Materialsparticipants: E. Carlström, L. Kahlman, S.Karlsson, E. Liden, R. Pompe, K. Rundgrencollaborators: Physics Dept. - Chalmers

C: Thermal Insulation Materialsparticipants: E. Liden, O. Lyckfeldtcollaborators: Physics Dept. - Chalmers

D: Ceramic Membranesparticipants: E. Liden, O. Lyckfeldtcollaborators: Physics Dept. - Chalmers

E: Processing of Traditional Ceramicsparticipants: S. Karlsson, A. Kristoffersson,R. Pompe, K. Rundgren

F: Inorganic Bindersparticipants: S. Karlsson

G: Technology Transfer and Standardisationparticipants: E. Carlström, L. Kahlman, R.Pompecollaborators: Powder Technology CenterGöteborg - Chalmers

N.B. In all research fields above obviously themember companies cf SCI and other companies thatare partners in co-operation are important collabora-tors but they are not specified separately.

Research ProjectsA: Processing of Engineering CeramicsA1: Freeze Granulation of Ceramic PowdersA2: Forming of Metal and Cemented Carbide

PowdersA3: The Development of a Low Cost Route for

Making Tough CeramicsA4: Fabrication of Si3N4 and Si2N2O-ZrO2

Composites by NPS Technique and Fabri-cation of Liquid Phase Sintered SiC Ceram-ics

A5: Development of Slips for Pressure SlipCasting and Filament Winding

B: Wear Resistant MaterialsB1: Wear Resistant Materials

C: Thermal Insulation MaterialsCl: Thermal Insulation Materials

D: Ceramic MembranesDl: Ceramic Membranes

E: Processing of Traditional CeramicsE1: High Strength Traditional PorcelainE2: Refractories for Melt and Warm-Holding

Furnaces for Aluminium and AluminiumAlloys

F: Inorganic BindersFl: Inorganic Binders

6: Technology Transfer and StandardisationG1: Technology Information on Engineering

CeramicsG2: Powder Technology 90 Acivities (PT90)G3: Pre-standard/Standardisation Activities

A l Freeze Granulation of Ceramic PowdersIn order to press ceramic bodies for sintering thepowder has to be granulated. The standard methodsfor granulation of ceramic powders consist of spraydrying and mechanical granulation. A method forfreeze granulation of powders has been developed atthe Swedish Ceramic Institute. A powder slurry issprayed into liquid nitrogen. The frozen droplets areremoved from the liquid nitrogen and freeze dried.The advantages with the freeze granulation are thatno migration takes place during freezing or drying

204 THE CENTRE FOR


(sublimation). This eliminates problems with bindermigration and inhomogenei ties caused by migrationof sintering additives that takes place when standardgranulation techniques, such as spray drying, areused. Another advantage is that the density of thegranules can be controlled. Low density granulesbreak down easily during pressing. Large porescaused by remnants of granules, not readily crushed,can be eliminated in the green body. During spray-drying the granule density iscontrolled by the stabil-ity of the slip. The density can only be reduced bydestabilizing the sup which has a number of disad-vantages. In spray-freezing the granule density canbe directly controlled by controlling the powdercontent of the slip.

The compaction behaviour of freeze dried gran-ules will be studied and compared with spray-driedgranules from a collaborative pressing project at theCenter for Ceramic Research at Rutgers University.The granule density - pressure relations necessaryfor a complete break down of the granules will bestudied. The influence of the granulation method onthe density gradients in the pressed green body willalso be characterized. The homogeneity of the pressedgreen bodies will be studied using image analysis inorder to quantify and describe the amount and scaleofinhomogeneities.

A2 Forming of Metal and CementedCarbide Powders

Forming ceramic powders to complex shapes byinjection molding and slip casting are well estab-lished techniques. Some more; recent methods thathave been developed for the forming of ceramicpowders are gel casting, pressure casting and freezeforming ("Quick Set"). More recently these methodshave been applied tocemented carbides and metallicmaterials. The injection molding of cemented car-bides is developed in this project together withPolymeric Materials and Engineering Metals atChalmers University of Technology. AB SandvikFormsprutning isbuilding a pilot plant facility for theforming of cemented carbide components by injec-tion molding and is another partner in this collabora-tive project. In powderinjection molding the powderis mixed with a polymer/wax binder and is thenmolded at high pressure in an injection moldingmachine. The polymeric binder then has to be re-moved prior to sintering. This is a time consumingstep where defects can easily be introduced into the

material. The Swedish Ceramic Institute has devel-oped a computer controlled method for removal oforganic temporary binder. The component is placedon a balance in a furnace and the weightloss rateduring heating is computed. The weightloss rate isused as a measurement to control the heating and inthis way control the binder removal. The method isbeing used to minimize the removal time whilemaintaining a high quality of the produced compo-nents. Injection molding of metals such as stainlesssteel is also investigated within the project.

Alternative methods to injection molding, suchas gel casting, pressure casting and freeze forming,are based on liquid forming media instead of poly-mers and waxes. The liquid based methods havelower mold costs, little need for binder removal andsome of them use less expensive equipment thaninjection molding. These methods are still at thedeveloping stage. Within this project such methodsare tried out on metal and cemented carbide pow-ders.

A3 The Development of a New Low Cost Routefor Making Tough Ceramics

Ceramic components with a fracture toughness anda reliability suitable for aircraft applications have sofar only been manufactured from long fiber compos-ites. An alternative method based on a laminatestructure, analogous with a marine shell, has beeninvented by B. Clegg at the University of Cam-bridge. Expensive ceramic fibers and slow and ex-pensive infiltration methods (chemical vapour infil-tration) can be avoided using this method. Themethod is being developed into a production methodwithin a BRITE/EURAM project. Tapes are devel-oped and manufactured (Tioxide) and methods forlaminating arid forming the tapes to components aredeveloped (Ceramique et Composites). These com-ponents will be tested as cornbustor linings foraerospace applications (Deutsche Aerospace, MTUand Volvo Flygmotor). The strengthening mecha-nisms, the microstructure and the mechanics of theinterface layers will be studied (Cambridge Univer-sity).

The current material is based on silicon carbidelaminated with carbon layers. A crack that developsin the brittle silicon carbide will be dispersed andstop at the weak carbon layer. In order to make thematerial even tougher and more resistant to oxida-tion, new interface layers will be developed. These


SWEDISH CERAMIC INSTITUTE. SCI

interface layers require tougher and stronger siliconcarbide layers. The layers will be developed at theSwedish Ceramic Institute using a liquid phasesintered silicon carbide with high toughness. SCIwill also improve the laminate by forming thinnertapes using both tape casting and calendering. Thecasting and calendering methods will be improvedusing colloid chemistry tocontrol the rheology of theceramic systems.

A4 Fabrication of SI3N4 and SI2N2OZ1Q2Composites by NPS Techniqueand Fabrication of UquM PhaseSintered S»C Ceramics

This is a cooperative project on structural ceramicsbetween The Centerfor Ceramic Research at RutgersUniversity, NJ, US A and Swedish Ceramic Institute.The aim of the project is to improve the mechanicalproperties, especiallythe fracture toughness, ofSi3N4,Si2N2O and SiC based ceramics. The materials areprocessed using colloidal methods, densified bypressureless sintering and the resulting mechanicaland microstructural properties are evaluated andcorrelated to the process used. In the sub-projectconcerning S13N4 and Si2N2O the objective is toexplore the potential of the NPS (Nitriding Pressure-less Sintering) technique forpreparation of dispersoidcomposites. The NPS technique features high greendensity (low linear shrinkage), fine (down to nano-size) particle size and fine/narrow pore size S13N4matrix which is important for optimal densificationof a composite system. Two types of systems arebeing investigated:

(a) a system with morphologically differentecond phase constituents such as SiC whisk-

ers and platelets,(b)a paniculate composite system with Z1O2

(PSZ) particles.

In the sub-project concerning LPS-SiC the aim is toexplore the potential of the LPS (Liquid PhaseSintering) technique for the preparation of siliconcarbide ceramics for wear applications. The aim isalso to evaluate high temperature creep (STSR) andoxidation resistance for LPS-SiC (and NPS-Si3N4, -S12N2O) ceramics for applications at a temperatureof 1200°C or higher.

A5 Development of Slips for Pressure SlipCasting and Filament Winding

The most interesting forming techniques for ceram-ics are based on colloidal processing techniques,where the powders are dispersed in a liquid (usuallywater). To develop the colloidal processing tech-niques, as for example pressure slip casting, it isimportant to have a knowledge of the rheologicalproperties ofthe slip used. The rheology is critical forthe results obtained at the forming stage and deter-mines the final propertiesof the ceramic component.SCI has carried out a project concerning pressure slipcasting of S13N4 gas turbine rotors. Spin test discshave been produced using a pressure slip castingmachine (Netzsch). In this project knowledge hasbeen built up in the area of pressure slip casting ofhigh performance ceramics and the results obtainedin the project have shown that this processing tech-nique has a great potential in the production of largerceramic components with complex geometries. Inthe case of pressure slip casting it might be desirableto use slips which are partially flocculated toenhancethe casting rate. In this case it is important to be ableto study and control the floe structures/sizes in theslip and relate this to the particle packing/greenmicrostructure as well as the casting properties.Production of long fibre composites by filamentwinding is another example of a forming techniquewhere the rheological behaviour of the ceramic slipis very critical for the results obtained. In this projectthe slips for both pressure slip casting and filamentwinding are developed.

B l Wear Resistant MaterialsCeramic materials can replace metals in applicationswhere it is of interest to have reduced weight, lowcoefficient of friction, chemical stability, high hard-ness and high temperature resistance. Despite disad-vantages smh as brittleness and in some cases ex-pensive raw materials or forming processes ceram-ics have a future as wear parts. The literature on wearis extensive but the majority of the publicationsconcentrate on wear testing using "standard" meth-ods. Very little information is given about the impor-tance of the relation between microstructure andwear properties in specific applications.

Within the project wear applications such asvalve trains, nozzles, seal rings, textile thread guidesetc are studied. It has been found that an R' factor ofcrack initiation by thermal shock is a good indicator

206 THE CENTRE FOR


of the resistance to abrasive wear. The R' factorincreases with increased thermal conductivity. Thematerial development of these materials has there-fore aimed at increasing this specific property to-gether with further improvements of the fracturestrength. In applications such as valve trains thechemical environment and lubrication are of impor-tance together with stress analysis in the compo-nents. This system is very specific and it is not easyto understand the mechanisms involved.

The main objectives within the project are

- general knowledge of ceramics inwear applications

- fabrication of prototype wear components- application oriented wear testing- iterative development of materials selection.

Cl Thermal Insulation MaterialsThere is a great interest in the automotive industry touse ceramic materials with low thermal conductivityfor insulation of engine parts where considerableheat losses are to be expected. An example is thedevelopment of ceramic port liners. The propertiesof ceramic port liners must be properly adjusted toallow for insert-casting into the cylinder head (alu-minium or cast iron), where they serve as thermalinsulation. This means that except for a low thermalconductivity (<2 W/mK) the ceramic material musthave very good thermal shock properties to resist thethermal shock of the metal casting (cast iron in thisproject). Furthermore, the ceramic material mustresist the shrinkage stresses exerted by the contract-ing metal during casting and the thermal stressesgenerated by thermal cycling in service life. Amongthe most studied materials for this application isaluminium-titanate (AI2T1O5) which has a low ther-mal conductivity, low thermal expansion and lowYoung's modulus and hence very good thermalshock properties. SCI has studied the developmentof Al-titanate but also other thermal insulation mate-rials such as porous cordierite and the socalled NZP-materials (sodium-zirconium-phosphate ceramics).Although it is possible to adjust the thermal proper-ties of the ceramic material to obtain better thermalshock properties, the results from earlier projects inthis area have shown that there are difficulties inachieving good reliability at the insert-casting stage.Therefore, it is important to develop a system that is"safe" so that insert-casting can be performed with-

out the risk of cracking of the ceramic component.Instead of producing ceramic port liners, the coat-ings of port liners is developed in this project. Thiscoating/interface layer should take up the compres-sion stresses from the shrinkage of the cast iron andhence make the whole insert-casting process morereliable. In order to understand the whole insert-casting process, stress analyses are necessary. Theproject is carried out in close cooperation with theautomotive industries, AB Volvo and Saab ScaniaAB. The casting experiments are made by thesecompanies.

Dl. Ceramic MembranesPolymeric membianes have been used for separa-tion methods (such as ultrafiftration, reverse osmo-sis, gas separation) for a long time in the processingindustry. The use of ceramic membranes representsa new technique that has generated much interest.Among the advantages of ceramic membranes canbe mentioned their good mechanical and high tem-perature properties and their resistance to chemicals.Ceramic membranes can have a catalytic functionbesides their selective function. The development ofsol-gel technology has greatly enhanced the per-formance capabilities and lowered the cost of mem-branes. Membranes in general are used in manydifferent applications and industries as for examplein Food and Beverages, Biotechnology/Pharmaceu-tical, Gas separation, Environmental control,Petrochemical, Metal refining and Electronics. Inthis project ceramic membranes are studied andknowledge is built up in the area of ceramic mem-branes and the most interesting applications for thesetypes of membranes are identified. Ceramic mem-branes are developed in the project by the use of sol-gel technology.

El High Strength Tradttloral PorcelainTraditional porcelains have bending strengths aroundSO to ISO MPa and a fracture toughness below 1MPam'/2. A traditional triaxial porcelain with acomposition including china clay, quartz and feld-spar is used as a model system. This project aims atincreasing the bending strength and the fracturetoughness so as to widen the application field of thematerial. One of the objectives of the project is to geta better understanding of which microstructural fea-tures enhance the mechanical strength. Reduction ofdefects such as agglomerates, porosity and cracks


SWEDISH CERAMIC INSTITUTE. SCI

surrounding large quartz particles has proven to besuccessful in increasing the strength. Toughening ofthe material through internal stresses (particle rein-forcement) achieved through thermal expansionmismatch between glassy phase and thequartz grainsis investigated. The processing methods includefreeze granulation of the powders and cold isostaticpressing of the test bars. The materials are character-ised by 4-point bending and fractography, fracturetoughness (CVNB-method), thermai expansion,phase composition and microstructure.

E2 Refractories for Melt and WamtHoMmgFurnaces for Aluminum and Aluminum Aloys

Aluminum as pure metal or as an alloy with elementssuch as silicon, iron, magnesium, zinc, nickel, silverand lithium is today used in many important indus-trial applications, e.g. in the automotive and theaircraft industry. In this project industrially used Al-alloys are studied in melted state in contact withdifferent refractories in melt furnaces of variouskinds. Corrosion tests in laboratory scale are used inorder to simulate the conditions in industrial fur-naces such as thermal stresses, atmosphere and slagproperties etc. A selection of interesting Al-alloys(Al-Mg, Al-Zn-Mg etc) and refractories (commercialand new ones produced at SCI) are studied. Parallelwith the laboratory tests, these combinations ofrefractories and Al-alloys are tested in real produc-tion furnaces. The project is mainly focused oncompanies melting Al and Al-alloys for the produc-tion of castings or materials for plastic machining.Producers of refractories are also members of thisproject as are manufacturers of furnaces for the Al-industry.

F l Inorganic Binders (Adhesive*)Inorganic binders such as colloidal silica sol,ethylsilicate, alumina sol, various phosphates, re-fractory cements and others are used in numerousapplications working at elevated temperatures. Se-lected applications such as ceramic shell moulds,refractory linings and refractory fibre preforms forthermal insulation or as reinforcements in metalmatrix composites (MMC) use one or several typesof inorganic binders. High strength and creep resist-ance at elevated temperatures are important proper-ties.

The project involves evaluation of suitable testmethods and knowledge how to modify inorganicbinders in order to improve the high temperatureresistance. Bending tests (4-point) using low loadingspeeds and bending creep tests have been usedtogether with more traditional compressive test meth-ods in the evaluation. The creep resistance of sodiumand ammonia stabilized silica sols isquite similar butdramatic improvements in load bearing capacity arereached when small amounts of alumina are present(for example canonic silica sol). Mullite formingsilica sols and alumina sols also show improvedresistance. Besides good mechanical properties athigh temperatures it is important as well that a bindergives enough green strength. In industrial applica-tions the binders must be able to work well in atemperature range from mom temperature up to atemperature limit set by each application.

Inorganic binders are not only used for hightemperature applications. Some binders have largepotentials as !ow temperature binders or construc-tion materials as well. Cold (Chemically) BondedCement (CBC) is a class of materials which hardenat low temperatures. Within the CBC group compo-sitions based on modified cements and aluminumphosphates are found. The materials are postulatedto have a future as construction materials working atlow and moderate temperatures. Chemical reactionsduring setting are studied.

G l Technology Informationon Engineering Ceramics

An important feature in the spreading ofinformationabout the potential of new materials is to bridge thegap between the material society and the engineeringdesigners in the industry. In order to bridge this gapSCI has a program directed toward users, especiallyin the mechanical industry and the process industry.During the initial stage new users can get freeconsultancy to discuss the possible use of ceramicsin new products. To inspire and to teach the engi-neering designers how to use ceramics, informationand design guides are drawn up. Design courses forpeople active in the industry are arranged in coopera-tion with the industry, other institutes and the univer-sities. These activities also give SCI good contactswith the users of ceramics and opportunities to learnabout their needs, which might serve as a guide forfuture development of engineering ceramics.

208 THE CENTRE FOR


G2 Powder technology 90 (PT 90) activitiesSCI has beer participating actively in the planningand implementing phase of the new action areaPOWDER TECHNOLOGY 90 (Pulverteknik 90)which is directed at product-oriented R & D withinboth the ceramic and the P/M area. The institute is amember of the Powder Technological Center inGothenburg (PTC-G) at Chalmers with the secre-tarial responsibility in its working committee. PTC-G is one of the four centers established at the univer-sity sites in Stockholm, Gothenburg, Luleå andLinköping. The Center has been given a specialR&D competence profile in the field of processingtechnology for large scale fabrication of nearly orfully dense components with near net shape (NNS).This profile fits closely with the R&D objectives ofSCI.

The institute makes its contribution both in theceramic and the P/M field. Together with otherdepartments at PTC-G and companies, new P/Mshaping techniques based on MIM (Metal InjectionMoulding) and other wet shaping methods are suc-cessfully being developed. As a result of a pre-studyconcerned with product and production develop-ment of structural ceramics and advanced refracto-ries a number of commercially viable product con-cepts have been proposed and corresponding projectsare being formulated in collaboration with the indus-try. A major project for development of ceramicmatrix composites (CMC) for combustion chamberin aircraft engines is under preparation.

A NUTEK study aimed at a new action areaentitled "Product and production technology fortechnically advanced ceramics for industrially quali-fied applications" has been carried out at SCI. Thepurpose is to create a complementary action area toPT 90 supporting the producers of technically ad-vanced ceramic components. As a result, a consor-tium has been formed at PTC-G with HöganäsEldfast AB and Ifö Ceramics AB as core companiesinvolved which will propose projects in the productareas of significant market potential.

Efficient technology transfer has been identifiedas one of the key aspects of the technological devel-opment of small and medium sized enterprises. Astudy has been carried out together with The Institutefor Production Engineering (IVF) to develop facili-ties at the PTC in Gothenburg and Luleå into iceramic pilot scale workshop. A comprehensive

questionnaire has been sent out to more than 100companies and evaluated. It has been clearly indi-cated that prototyping, testing and evaluation of newproduct concepts and long-term development con-tracts are particularly attractive for user companies.

A project proposal for establishment of such apilot scale facility has been prepared and is expectedto reach the implementation phase during the fiscalyear 1992/93.

G3 Pre-standard/standanlsatk>n activitiesA broad market introduction of structural ceramiccomponents calls for standardised test methods cov-ering the whole processing route (rom raw materialsto finished products. Because of the novel and stillstrongly generic nature of this field, a considerablepre-standardisation research effort is required inorder to identify the factors which are significant forthe standard test methods under development. SCI isinvolved in both types of activities:

(a) pre-standardisation work within IEA (Interna-tional Energy Agency) including major com-panies and organisations in the US, Germanyand Japan,

(b) standardisation of test methods within MNCTC 301 and CEN technical committee TC 184which works on a special mandate from theEG/EFTA countries.

In the framework of the IEA collaboration the insti-tute is involved in method development for powdercharacterization and mechanical testing. The re-sponsibilities also include data evaluation for thefinal reports and technical leadership within specificpowder analysis areas. SCI is responsible for techni-cal coordination of the IEA work in Sweden.

Within the standardisation field the institute isactive via the membership in MNC (TK 301Keramer). A program involving a total of 52 stand-ard methods in five different working fields is undertreatment with the goal toestablish European stand-ards by 1992. SCI has a member representing Swe-den in the CEN/TC184 international technical com-mittee and in the working group concerned withpowder standards.

The work within IEA and CEN/TC 184 has beencoordinated by the working group for engine andhigh temperature ceramics established by NUTEK.



PublicationsPh.D. DissertationsE. Carlström, "Defect Minimisation in Silicon Carbide,

Silicon Nitride and Alumina Ceramics", Jan'90R. Lundberg, "Fibre Reinforced Ceramic Composites",

Sept'89M. Persson, "Slip Casting and Pressing of Ceramics based

on Colloidal Processing Techniques", Dec'89

Diploma WorkB. Carlsson, "The Mechanisms Behind Textile Wear of

Ceramic Thread Guides", Oct'92J. Forshamn, "Aluminium Phosphate Bonded Ceramic

Coalings on Metal", Feb'93A. Kristoffersson, "Fast Drying Binder System for Ceramic

Shell Moulds", May'920. Lyckfeldt, "Stabilisation and Slip Casting of Silicon and

Silicon Nitride in Organic Media", Sept'9ON. Modig. "Preparation and Evaluation of Sintered Silicon

Nitride and Gas Pressure Sintered Silicon Nitride",Feb'93

G. Sjögren, "Effect of Carbon and Iron Impurities DuringNilridation and Sintering of Silicon Nitride", May'89

G. Skoglund, "Development of a Reaction-bondedAlumina and Mullite Matrix for Ceramic Long FibreComposites", Nov'92

A. Rubenowitz, "Ceramic Wear Coatings on Bioimplantsof Titanium Based on Sol- gel Technique", April'90

A. Törnkrona, "Inorganic Binders for High Temperatures",Dec'91

A. Warren, "Development of Oxide Long Fibre Compos-ites by Slurry Infiltration and Reaction Bonding",April'93

Engineering Ceramics1. Tjcmlund A K, Pompe R, Holmström M, och Carlsson

R: "Sintering and Phase Studies m the SystemSi3N4-ZrO2-Al2O3", Advances in Ceramics, Vol. 24B,Science and Technology of Zirconia III, 101S-1021(1988)

2. Rundgren K, Elfving P, Pompe R, Lagerlöf P ochLarsson B: Comparative Study of Sol-Gel PreparedMullite and Mullite-ZKh Composites with and withoutY2O3" Advances in Ceramics, Vol 24, Science andTechnology of Zirconia III, 1043-1052 (1988)

3. Carlström E: "Reserapport från forskarvistclse i Japanvid GIRI Nagoya 23 sept - 23 okt 87", SILIKAT-RAPPORT 884 (1988)

4. Carlsson R: "Finns någon kunskap om kcramiskamaterial", IVA-rapport 338: Nya material iproduktionen: Företagens strategi för införande av nyteknik, p. 113-120(1988)

5. Carlström E, Sjöstedt M, Mattsson B and HermanssonL: "Binder Removal from Injection Moulded CeramicTurbocharger Rotors", Science of Ceramics 14, ed byDerek Taylor, p. 199-204 (1988)

6. Lundberg R, Pompe R, Carlsson R: "HIPed CarbonFiber Reinforced Silicon Nitride Composites", Ceram.Eng. Sci. Proc., 9 (7-8), 901-906 (1988)

7. Lundberg R, Nyberg B, Williandcr K, Persson M,Carlsson R: "Glass Encapsulated HIPing of SiCWhisker Reinforced Ceramic Composites", Proc. FirstInt. Conf. HIP, Luleå, cd. by Garvare T, Centck Publ.323-327 (1988)

8. Carlsson R, Adlerborn J, Dahlberg R, Lindberg J,Mellgard I och Regestad G: "Kerampansar", förstudieinom STU:s insatsområde "Konstruktionskeramer", 16sidor (1988)

9. Lundberg R: "Fiberförslärkla kcramcr", JcmkontorctsForskning D627,8061/87 (1988)

10. Ekberg I-L, Lundberg R, Warren R and Carlsson R:"Indentation Testing of SiC-Whiskcr Reinforced AI2O3Composites", Brittle Matrix Compositcs-II, ElscvicrPubl. (1988)

11. Bostedt E: "Mctallalkoxidcr - en litteraturstudie",KeramRapport 89-1(1989)

12. Bostedt E och Persson M: "Yimodificring avkcramiska material", KcramRapport 89-2 (1989)

13. Brandt J och Persson M: "Utvärdering av modernatryckgjutningsmetoder för formning avkonstruktionskeramer - en förstudie", Kcram-Rapport89-3 (1989)

14. Sjögren G: "Föroreningars form och roll vidframställning av Si3N4-bascradc kon-struktionskeramer", KcramRapport 89-4 (1989)

15. Lindqvist K, Carlström E, Persson M and Carlsson R:"Organic Silanes and Titanales as Processing Additivesfor Injection Moulding of Ceramics", J. Am. Ccram.Soc. 72 [1199-103 (1989)

16. Carlström E, Persson M, Bostedt E, Kristoffersson Aand Carlsson R: "Slip Casting and Sintering of SiliconCarbide", Ceramic Transactions Vol 2, Silicon Carbide'87, Am Ceram Soc. Columbus, 175-1,5, (1989)

17. Carlsson R: "The Shaping of Engineering Ceramics",Materials & Design, 10 (1), 10-14 (1989)

18. Carlsson R: "Kcramcr som pansarmatcrial", MilitärTeknisk Tidskrift, 58 (1), 19-25 (1989)

210 THE CENTRE FOR


19. Lundberg R and Goursat P: "Silicon Carbo-NitrideCeramic Matrix Composites by Polymer Pyrolysis",Proc. Inl Conf. ECCM-3, Bordeaux, 93-98 (1989)

20. Nyberg B, Carlström E, Persson M and Carlsson R:"Uniform Distribution of a Pressing Aid", Proc. 2ndInt. Conf. Ceramic Powder Processing Science, 573-580(1989)

21. Lindqvist K, Carlström E and Carlsson R: "LowPressure Injection Molding of Alumina", Proc. 2nd IntConf. Ceramic Powder Processing Science, 589-597(1989)

22. Bostedt E, Persson M and Carlsson R: "ColloidalProcessing Through Surface Modification", Euro-Ceramics Vol 1: Processing of Ceramics, pp. 1.140-1.144(1989)

23. Holmström M, Charticr T, Besson J-L and Boch P:"Influence of Z1O2 on the Preparation and Properties ofTape-Cast, Laminated, ZrC -Mullite Composites",Euro-Ceramics, Vol 1: Processing of Ceramics, pp.1.299-1303(1989)

24. Falk L K L and Holmström M: "MicrostructuralDevelopment During Processing of a SisNVZrC^Material", Euro-Ceramics, Vol 1: Processing ofCeramics, pp. 1.373-1.377(1989)

25. Brown 1W M, Pompe R and Carlsson R: "Preparationof Sialons by the NPS Technique", Euro-Ceramics Vol1: Processing of Ceramics, pp. 1.484-1.488(1989)

26. Rundgren K, Pompe R, Carlsson R, Kishi K andUmcbayashi S: "On the Reaction Mechanism andMechanical Properties of Nitrided PressurclcssSintered (NPS) Siafy-ZrCty+Y^) CompositeCeramics", Euro-Ceramics Vol 1: Processing ofCeramics, pp. 1.489-1.493 (1989)

27. Linde K M, Persson M, Pompe R, Karlsson S andCarlsson R: "Iterative Strength Development of SlipCast SJ3N4", Euro-Ceramics, Vol 3: EngineeringCeramics, pp. 3.126-3.130, (1989)

28. Carlsson R, Garvare T, Karlsson L och Warren R:"Fogning Keram-Metall", förstudie inom STU:sinsatsområde "Konstruktionskeramer", 9 sidor (1989)

29. Carlström E: "Konstruktionskeramcr",kurskompendium, 44 sidor (1989)

30. Lundberg R: "Fibre Reinforced Ceramic Composites",Ph. D. Thesis, Chalmers tekniska högskola, Göteborg(1989)

31. Persson M: "Slip Casting and Pressing of Ceramicsbased on Colloidal Processing Techniques", Ph. D.Thesis, Chalmers tekniska högskola, Göteborg (1989)

32. Carlström E: "Defect Minimisation in Silicon Carbide,Silicon Nitride and Alumina Ceramics", Ph. D. Thesis,Chalmers tekniska högskola, Göteborg (1989)

33. Kahlman L: "Metoder och uTustning för bearbetningoch mekanisk testning av konstruktionskeramer",KeramRapport 89-6 (1989)

34. Falk L K L, Hermansson T, Rundgren K: "Microstruc-ture of Hot-Pressed Si3N4-ZrO2 (Y2O3) Composites",J. Mäter. Sci. Letters, 1032-1034 (1989)

35. Swan A H, Olsson E, Linde K M and Lundberg R:"The influence of Microstnicture on the MechanicalProperties of SiC Whisker Reinforced Si3N4", Proc.5th SSMS Conf. New Materials & Processes. Copen-hagen (1989)

36. Persson M: "Adsorption and Stabilization of Aluminain Water by High Molecular Weight Polyacrylic Acid",in M. Perssons's Ph.D. Thesis "Slip Casting andPressing of Ceramics based on Colloidal ProcessingTechniques", Chalmers tekniska högskola, Göteborg(1989)

37. Karlsson S: "Forskarvistelse vid GIRI Osaka, Japanhösten 1989. Reserapport", KcramRappon90-l (1990)

38. Rubcnowitz A, Bostedt E och Persson M: "Keramiskanötningsskikt pä bioimplantat av titan med hjälp av sol-gel teknik", KeramRapport 90-2 (1990)

39. Kahlman L: "Konstruktionskeramer i världen 1990.Dagsläge och prognos", KeramRapport 90-3 (1990)

40. Linde K, Karlsson S: "Oförstörande provning -utvärdering av några metoder för karakterisering avA^Oj-fibcrförformar samt Si3N4 i grönt och sintrattillstånd", KeramRapport 9(M (1990)

41. Ekberg I-L: "Högtemperaiuregcnskaper hos Si3N4:Litteraturreferat", KeramRapport 90-6 (1990)

42. LyckfeldtO, Persson M och Liden E: "Dispergeringoch slamgjutning av kisel och kiselnitrid i organiskasystem", KeramRapport 90-7 (1990)

43. Lindqvist K och Carlström C: "Extrudering av keramer- en litteraturstudie", KcramRappon 90-8 (1990)

44. Lundberg R, Pompe R, Carlsson R and Goursat P:"Fibre Reinforced Silicon Nitride Composites",Composites Science and Technology, 37,165-176(1990)

45. Manguin-Frilsch A, Dubus M, Abouaf M, Du MouzaJ, Carlström E, Sjöstedt M, Mustcl W: "Optimizationof binder removal in injection molding of technicalceramics", Euram final report, 1990



46. Pompc R: "Prospects for Non-Oxide PaniculateComposites at High Temperatures, Proc. 1 lth Rist» Int.Symp. on Metallurgy and Materials Science: StructuralCeramics - Processing, Microstructure and Properties,Ris0 Nat Lai)., Roskilde, 97 -110 (1990)

47. Bergström L and Lyckfeldt O: "Adsorption Behaviourand Dispersion of S13N4 Powders in Non-AqueousMedia", Proc. 1 lth Ris0 Int. Symp. on Metallurgy andMaterials Science: Structural Ceramics - Processing,Microstructure and Properties, Ris0 Nat Lab., Ros-kilde, 193-198(1990)

48. Karlsson S and Iwasa M: "Wear Behaviour of SiliconNitride Based Ceramics", Proc. 1 lth Rise Int. Symp.on Metallurgy and Materials Science: StructuralCeramics - Processing, Microstructure and Properties,Rise Nat Lab., Roskilde, 365 - 370 (1990)

49. Resetar T M, Schaefer G E, McCauley J W, Dragoo AL, Hsu S M, Johnsson D R, Hausner H and Pompe R:"IEA/Annex II Powder Characterization CooperativeProgram", Ceramic Transactions, Vol 12, CeramicPowder Science III, 1990

50. Emslsson M, Bergström L, Nyberg B, Lundberg R,and Gruvin B: "Processing of Silicon Nitride Powders,I: Panicle Size and Morphology Determination UsingMie Scattering and X-ray Sedimentation", CeramicTransactions, Vol 12. Ceramic Powder Science III,835-843 (1990)

51. Nyberg B, Lundberg R, Carlström E, Fmstsson M andBergström L: "Processing of Silicon Nitride Powders,II: Morphology - Pressability Relationships", CeramicTransactions, Vol 12, Ceramic Powder Science III,845-853 (1990)

52. Bergström L and Bostcdt E: "Surface Chemistry ofSilicon Nitride Powders: Electrokinetic Behaviour andESCA Studies", Colloids and Surfaces, 49,183-197(1990)

53. B'cwn IW M, Pompe R and Carlsson R: "Preparationof SiAlONs by the Nitridcd Pressurelsss Sintering(NPS) Technique", J. Europ. Ceram. Soc. 6,191-200(1990)

54. O'Mcara C, Pömpe R and Rundgren K: "The Mic-rostructure of Si2N207ZrO2 Composite Ceramics",Proc. 7th CIMTEC, "Advanced Structural InorganicComposites" 179-187(1991)

55. Bergström L, Emstsson M, Gruvin B, Brage R, NybergB and Carlström E: "The Effect of Wet and DryMilling on the Surface Properties of Silicon NitridePowders", Proc. 7th CIMTEC, "Ceramics Today -Tomorrow's Ceramics", 1005-1014 (1991)

56. Lyckfeldt O, Bostedt E, Persson M, Carlsson R andBergström L: "Stabilization and Slip Casting of Siliconand Silicon Nitride in a Non-Aqueous Media", Proc.7th CIMTEC, "Ceramics Today - Tomorrow's Ceram-ics", 1073-1082 (1991)

57. Malghan S G, Dragoo A L, Hsu S M, Hausner H andPompe R: "Physical and Chemical Characterization ofCeramic Powders in an International InterlaboraloryComparison Programme", Proc. 7th CIMTEC, "Ce-rarnxs Today -Tomorrow's Ceramics" 3249-3259(1991)

58. Liden E, Persson M, Carlström E and Carlsson R:"Electrostatic Adsorption of a Colloidal SinteringAgent on Silicon Nitride Panicles", J. Am. Ceram.Soc., 74 [6] 1335-1339(1991)

59. Lindqvist O, Sjöberg J, Hull S and Pompe R: "Struc-tural Changes in O'-Sialons, Si2.xAl,N2.xO|+x,004<x£040", Acta Crystallographica B47,672-678(1991)

60. Bergström L and Liden E: "Effects of Surface Modifi-cation on the Adsorption Behaviour and Dispersion ofSilicon Nitride Powders in Non-Aqueous Media",Ceramic Transactions, Vol 22, Ceramic PowderScience IV, 289-295 (1991)

61. Lyckfeldt O, Pömpe R and Liden E: "Non-Aqueous,Centrifugal Casting of Silicon Nitride", CeramicTransactions, Vol 22, Ceramic Powder Science IV,329-334(1991)

62. Liden E, Bergström L, Persson M and Carlsson R:"Surface Modification and Dispersion of SiliconNitride and Silicon Carbide Powders", J. Europ.Ceram. Soc. 7 361-368 (1991)

63. Liden E, Carlsson R, Persson M and Bergström L:"Surface Modification of Oxide and Non-OxideCeramic Powders", Proc. Centennial InternationalSymposium "Ceramics: Toward the 21st Century",482499(1991)

64. Pompe R: "Konferens- och studiebesök i Japan våren1991. Reserapport", KcramRapport91-l (1991)

65. Eriksson P och Kahlman L: "Elektriskt ledande Si3N4-TiN-komposiier", KeramRappon 91-2 (1991)

66. Lyckfeldt O, Liden E: "Värmcisolerandc kcramiskamaterial. Litteraturrapport", KcramRapport 91-3(1991)

67. Karlsson H och Karlsson S: "Fogning av kcram/tnclall- genom limning", (IVF-skrift91833), KeramRappon91-4(1991)

212 THE CENTRE FOR


68. Falk L K L and Rundgren K: "Microstructurc andShort-Tom Oxidation of Hot-Pressed S13N4/ZIO2(+Y2QJ) Ceramics", J. Am. Ceram. Soc. 75 [1]28-35 (1992)

69. Pettersson ABA, Bytnan-Fagerholm H andRosenholm J B: "Surface Acid-Base and ElectrokineticProperties of S i ^ , Z1O2, AI2O3, Y2Q3 and T1O2Powders", Proc. 4th Int. Symp. on Ceramic Materials& Components for Engines, Elsevier, 260-268 (1992)

70. Sjöberg J and Pompe R: "Structural Details of Sialons -Their Influence on Phase Stability", Proc. 4th IntSymp. on Ceramic Materials & Components forEngines, Elsevier, 269-276 (1992)

71. Cheng Y, O'Meara C, Slasor S. Pompe R andThompson D P: "Some Features and Limitations ofZirconia Toughened Nitrogen Ceramics", Proc. 4th Int.Symp. on Ceramic Materials & Components forEngines, Elsevier, 657-664 (1992)

72. Lundberg R, Scenholm T, Pcjryd L and Kahlman L:"The Influence of Static Loads on the OxidationBehaviour of Fibre Reinforced SiC/SiC Composites",Proc. 4th Int Symp. on Ceramic Materials & Compo-nents for Engines, Elsevier. 691-698 (1992)

73. Brandt J, Rundgren K, Pompe R, Lundberg R andPejryd L: "Development of Silicon Nitride BasedMatrices" Proc. 4th Int Symp. on Ceramic Materials &Components for Engines, Elsevier, 765-772 (1992)

74. Malghan S G, Hsu S M, Dragoo A L, Hausner H andPompe R: "Analysis of Physical Properties of CeramicPowders in an International Intcrlaboratory Compari-son Program", Proc. 4th Int. Symp. on CeramicMaterials & Components for Engines, Elsevicr, 920-935 (1992)

75. Brandt J, Kahlman L, Pompe R and Lindblad K-E:"Manufacturing of Ceramic Valve Discs and Their Usein a Rotor Cam Engine", Proc. 4th Int. Symp. onCeramic Materials & Components for Engines,Elsevier, 1093-1100(1992)

76. Brandt J, Rundgren K, Pompe R, Swan H, O'Mcara C,Lundberg R and Pejryd L: "SiC Continuous Fibcr-Rcinforced S13N4 by Infiltration and Reaction Bond-ing", Ceram. Eng. Sci. Proc. 13 [9-10]part2of2,622-631 (1992)

77. Kahlman L: "Konstruera rätt med keramcr",kurskompendium "Konstruera rätt med keramcr",Trollhättan, 20 sidor (1992)

78. Karlsson S: "Limning av keramcr", kurskompendium"Konstruera rätt med kcramcr", Trollhättan 11 sidor(1992)

79. Carlström E: "Konstruktionskcramer", SKSkurskompendium "Keramiska material", 51 sidor(1992)

80. Kahlman L: "Konstruera rätt med keramer",kurskompendium "Konstruera rätt med ke.-amer",Kristianstad, 20 sidor (1992)

81. Karlsson S: "Fogning av keramer", kurskompendium"Konstruera rätt med keramcr", Kristianstad, 30 sidor(1992)

82. Rundgren K, Brandt J, Pompe R and Carlsson R:"Low-Cost Nitrided Pressurcless Sintered (NPS)S12N2O-Z1O2 Composites", Proc. European CeramicSociety Second Conference, Augsburg 1991 (to bepublished)

83. Lyckfeldt O, Pompe R, Liden E and Carlsson R:"Fabrication of Nitrided Pressurcless Sintered (NPS)Silicon Nitride by Slip Casting", Proc. EuropeanCeramic Society Second Conference, Augsburg 1991(to be published)

84. Liden E, Carlsson R, Persson M and Bergström L:"Surface Modification of Ceramic Powders", Proc.European Ceramic Society Second Conference,Augsburg 1991 (to be published)

85. Byman-Fagerholm H, Liden E, Carlsson R andRosenholm J-B: "Slip Casting and PressurclessSintering of Si3N4-Zr02 Composites", Proc. EuropeanCeramic Society Second Conference, Augsburg 1991(to be published)

86. Nyberg B, Carlström E and Carlsson R: "Granulationof Ceramic Powders for Pressing by Spray-Freezing",Proc. European Ceramic Society Second Conference,Augsburg 1991 (to be published)

87. Kishi K, Umcbayashi S, Rundgren K and Elfving P:"Room Temperature Strength of B-Sialon (z=2)Fabricated from ct-Si3N4, AIN and Aluminum-iso-propoxide Solution", J. Mater. Sci. Let. (to be publish-ed) (1992)

Traditional Ceramics1. Carlsson R: "Mechanisms of Deterioration in Ceramics

and Glass", Durability of Building Materials 5,421-27(1988)

2. Fanto M, Pompc R, Sandrén Å och Carlsson R:"Eldfasta keramiska massor för induktionsugnar inomgjuteriindustrin", SIL1KAT-RAPPORT 88-1 (1988)

3. Karlsson S: "Alkalisilikatcr somhögtcmpcraiurbindemcdcl - Litteraturstudie",SILIKAT-RAPPORT 88-2 (1988)



4. KarlssonS och Lundberg R: "Långtidsegenskaper hoskeramiska fibrer för ugnsisolering", SILIKAT-RAPPORT 88-5 (1988)

5. Karlsson S.Lundberg Rand Carlsson R: TensileStrength of Ceramic Thermal Insulation Fibres".Science of Ceramics 14, ed by Taylor D, Canterbury1987 p. 633-637

6. Karlsson Sand Carlsson R: "Adhesive Force of SlipCast Body to Plaster Mould Surface", ibid p. 157-162

7. Holmström M, Persson M and Carlsson R: "Viscosityand Flow Behaviour of Glaze Melts", ibid p. 359-364

8. Nildasson U: "Framställning med pulverteknik ochdispergeringsförsök av högtemperaturesupraledarenYiBa2CujO7.x", SILIKAT-RAPPORT 88-7 (1988)

9. Nordänger S och Carlström E: "Framställning avsupraledaren YiBa2Cu3<>7.x med pulverteknik",SILIKAT-RAPPORT 88-9 (1988)

10. Karlsson S: "Lösliga alkalisilikater som bindemedel föroorganiska material. Hållfasthet och fuktupptagning",SILIKAT-RAPPORT 88-10 (1988)

11. Blomström P och Carlström E: "Studie avsintringsförioppet hos YiBa^ujOy., keramerframställda med sol-gel teknik", SILIKAT- RAPPORT88-12(1988)

12. Pompe R, Carlsson R and Sandrén Å: "On the Reac-tions Involving Refractories for Aluminum Casting",Proc. UNITECR '89, Vol 1,906-911 (1989)

13. Karlsson S and Carlsson R: "Pore Structure in PlasterMoulds", Euro-Ceramics, Vol 2: Properties of Ceram-ics, pp. 2.533-2.537, ed by de With G, Terpstra R A andMetselaarR(1989)

14. Karlsson S, Carlsson R and Ahmad B: "ColourDevelopment in Unglazed Floor Tiles", Euro-Ceram-ics, Vol 2: Properties of Ceramics, pp. 2.538-2.542, edby de With G, Terpstra RA and Metselaar R (1989)

15. Linde K M, Karlsson S and Carlsson R: "WearProperties of Ceramic Whiteware Glazes", Euro-Ceramics, Vol 3: Engineering Ceramics, pp. 3.559-3.563, ed by de With G, Terpstra RA and Metselaar R(1989)

16. Karlsson S: Torskarvistelse vid GIRI Osaka, Japanhösten 1989. Reserapport". KeramRapport90-l (1990)

17. Linde K och Karlsson S: "Oförstörande provnin? •utvärdering av några metoder för karakterisering avAl2O3-fiberförformar samt S13N4 i grönt och sintratUllstånd", KeramRapport 904 (1990)

18. Karlsson S: "Keramiska fiberförformar föraluminiumkompositer, tillverkning ochkarakterisering", KeramRapport 90-5 (1990)

19. Linde K: "Glasyrers slitageegenskaper -1",KeramRapport 90-9 (1990)

20. Linde K: "Glasyrers slitageegenskaper - II",KeramRapport 90-10 (1990)

21. Linde K: "Keramer och OFP", NDT forum 1,5 (1990)

22. Carlsson R: "Brewing av keramiska material - teori",SKS kurskompendium "Bränning i keramisk industri",15 sidor (1991)

23. Ekberg IL, Persson M och Carlsson R: "StrengthImprovements of a Traditional Feldspar Porcelain byDefect Minimization", Proc. Silicer 90, Fort-schrittsberichte der DKG, 7 [1], 247-254 (1992)

24. Tömcrona A, Karlsson S och Persson M: "Oorganiskabindemedel för höga temperaturer", KeramRapport 92-1(1992)

25. Persson M, Törncrona A and Karlsson S: "Evaluationof Silica Sols as Ceramic Shell Binders at HighTemperatures", kurskompendium (1992)

26. Carlsson R: "Tillverkning av keramiska material - enintroduktion", SKS kurskompendium "KeramiskaMaterial", 14 sidor (1992)

27. Carlsson R: "Bränning av keramiska material - teori",SKS kurskompendium "Keramiska material", 21 sidor(1992)

28. Karlsson S, Linde K och Karlsson R: "On the Influenceof Glaze Properties on Glaze Damage", Proc. EuropeanCeramic Society Second Conference, Augsburg 1991(to be published) (1992)

29. Shirazi A R, Eklund L and Lindqvist O: "DirectQuantitative Analysis of Mineral Matter and DifferentPyritic Sulphurs in Coal by Electron Probe MicroAnalyser (EPMA) and Automatic Ii.iage Analysis(AIA)" (to be published) (1992)

214 THE CENTRE FOR

MetalsEngineering Metals 216Microscopy and Microanalysis 228Mechanics - Swedish National Testing

and Research Institute, SP 240


Engineering Metals

Research summaryThe research activities in the Department of Engi-neering Metals are concentrated in the followingareas: materials for high temperature applications,powder metallurgy; corrosion and surface treat-ment; mechanical properties of metals and ceramics;joining technology.

In the research on high temperature materials,special interest is taken in the development of inter-metallics; silicides and aluminides. The aim is toimprove the room temperature ductility and stillpreserve good high temperature properties. Theintermetallic materials studied are syntesized bymeans of powder metallurgical (PM) methods. Amodern PM technique - Metal Injection Moulding -is treated in another project The objective of theproject is to gain understanding about binder/pow-der interactions. The use of surface sensitive tech-niques (ESCA, AES) for studying surface productformation related to powder fabrication and consoli-dation comprises a major part of the current PMresearch. One example is in the development of newPM produced martensitic stainless steel for steamturbine applications. Another example is a projectaiming at development of methods for surface clean-ing of high alloy powder. Studies of the influence ofpore and precipitate characteristics on dynamicproperties of PM stainless steel have recently beeninitiated.

The corrosion research has so far been focused onfundamental studies of thedissolution and passivationof stainless steel. One current subject is the passivationof austenitic stainless steel in hydrochloric acid upto 70°C. Another project deals with thin intermetallicfilms formed by means of sputtering technique. Thedepositedfilmsarecharacterised (ESCA, AES.EDX,etc) and their electrochemical properties are studied.

Extensive work dealing with the mechanical prop-erties of high performance materials is carried out.The prime interest is dynamic properties of materi-als. Materials concerned are duplex stainless steeland aluminium-base composites. The stainless steelstudied has various phase (austeni te/ferrite) content.The aim is to clarify the fracture behaviour of the

216

materials when subjected to controlled fatigue crackgrowth, cyclic deformation and low cycle fatigue.

The research on high temperature materials con-cerns in addition to intermetallics also ceramics andfibre reinforced ceramics. Particular interest is takenin studying deformation and fracture under staticload at 20-1500°C. The research on ceramics isfurther extended to studies of brazed metal/ceramicjoints. The aim is to develop reactive brazes for hightemperature applications, e.g. nickel alloy/siliconnitride joints. Another area where joining problemsare investigated is adhesive bonding of metals forstructural applications. The primary objective forthis activity is to improve the bonding beween thepolymer adhesive and the oxide on the metal surfaceby pre-treatment. Focus is placed on aluminiumalloys.

AddressDepartment of Engineering MetalsChalmers University of TechnologyS-412 96 Göteborg,!SwedenPhone+46 31 772 1263Fax+46 31 772 1262

StaffSenior membersOlefjord IngemarKarlsson BirgerLi ChanghaiNyborg LarsMattson HåkanWasén Jonas

Graduate studentsBörjesson SusanneHansson ThomasHolmquist MagnusHolmström MariaLevin MagnusLindstedt UlfNorell Mats

professor/prefektprofessordocentdocenttekn.dr.tekn.dr.

fil.kand.tekn.lic.civ.ing.civ.ing.tekn.lic.civ.ing.civ.ing.

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Nylund AndersNyström MagnusSvensson PatrikTunberg ThomasWegrelius LenaWarren Anna

Technical staffBragée JanFritze GöranHeiskanen PerttiJelvestam UrbanKjellgren UllaOlefjord YvonneSotkovszki Peter

SecretaryMaxe MariaNorden Marita

tekn.lic.tekn.lic.berging.tekn.lic.tekn.lic.civ.ing.

civ.ing.ing.ing.ing.

fil. kand.Dr. ing.

Major instrumentationPrime contact: Professor Ingemar Olefjord (phone772 1241)

ESCA (Electron Spectroscopy for ChemicalAnalysis), PHI 5500, small spot 50 \m lateralresolution. Secondary contact: Anders Nylund(phone 772 1261/772 1259).

SIMS (Secondary Ion Mass Spectrometry),PHI 3700, static, masses 0-250 amu.Secondary contact: Håkan Mattson (phone 7721243/7721259).

AES (Auger Electron Spectroscopy), PHI 660,Auger microprobe, 0.1 Mm analytical and 0.03pm imaging (SEM) resolutions. Equipped withLink Systems AN 10000 for quantitative X-raymicroanalysis. Secondary contact: LarsNyborg (phone 772 1257/772 1259).

Sputtering equipment for preparation of thinalloy layer on substrate. Equipped with doubleion guns and targets. Secondary contact: UrbanJelvestam (phone 772 1256).

Microscopy and materials testing. Primecontact: Professor Birger Karlsson (phone 7721242).

ENGINEERING METALS

SEM (Scanning Electron Microscopy), JEOL733, microprobe, quantitative X-ray micro-analysis. Secondary contact: Changhai Li(phone 772 1246).

Hardness testing equipment and optical micro-scopes with microhardness measuring facility.Secondary contact: Peter Sotkovszki (phone777 1255)

Impact/tensile testing machines. Secondarycontact: Jonas Wasén (phone 772 1245)

Servohydraulic testing machines, Instron 8032/8502, maximum load 100 kN. Secondarycontact: Jonas Wasén.

Dedicated testing machine for creep andtensile testing of brittle materials up to 1600°C.Secondary contact: Jonas Wasén.

Bend testing machine for measuring fracturetoughness of brittle materials up to 135O°C.Secondary contact: Jonas Wasén.

Laboratory vacuum sintering furnace for tempe-ratures up to 1600°C. Equipped with diffusionpump for high vacuum performance. Second-ary contact: Lars Nyborg (phone 7721257)

Dedicated vacuum furnace for wetting experi-ments up to 1200°C. Equipped with diffusionpump for high vacuum performance. Secondarycontact: Maria Holmström (phone 772 1258)

Laboratory atomization unit (Rotating ElectrodeProcess) for inert fabrication of metal powder.Secondary contact: Lars Nyborg (phone 7721257).

Laboratory annealing furnace for processsimul^on in hydrogen/nitrogen atmosphereup to 850°C. Secondary contact: UrbanJelvestam (phoe 772 1256).


ENGINEERING METALS


A: Corrosion and Surface TechnologyParticipants: professor Ingemar Olefjord, tekn.dr. Håkan Mattson, tekn. lic. Anders Nylund,tekn. lic. Lena Wegrelius, civ.ing. SusanneBörjesson, civ.ing. Magnus Holmquist, ing.Urban Jelvestam.Co-workers: Professor C Qayton, Stony BrookUniversity, N.Y. Directeur de Recherches, Dr.P. Marcus, CNRS, Ecole Nationale Superieurede Chemie de Paris. Professor M. Lakatos-Varsanyi, Eötvös University, Budapest.

B: Mechanical PropertiesParticipants: professor Birger Karlsson, tekn.dr. Jonas Wasén, tekn. lie. Magnus Levin,tekn. lie. Magnus Nyström.

C: Powder MetallurgyParticipants: professor Ingemar Olefjord,professor Birger Karlsson, docent Lars Nyborg,docent Changhai Li, tekn. lic. Anders Nylund,teka lic Thomas Tunberg, civ.ing. Mats Norell,civ.ing. Ulf Lindstedt.Co-workers: docent B. Uhrenius, SwedishInstitute for Metals Research, riving. T. Rost-vall, AB Sandvik Formsprutning, civ. ing. U.Engström, Höganäs AB, tekn. dr. A. Salwén,ABB Powdermet

D: Intermetalllcs andStructural Ceramics

Participants: professor Ingemar Olefjord,professor Birger Karlsson, professor RichardWarren (Luleå University of Technology),docent Changhai Li, docent Lars Nyborg, tekn.dr. Jonas Wasén, tekn. lic. Thomas Hansson,civ.ing. Maria Holmström, civ.ing. PatrikSvenssonCo-workers: docent B. Uhrenius, SwedishInstitute for Metals Research, tekn. lic. L.Léstrade, Itec AB, docent T. Thorvaldsson, ABSandvik Steel

Research Projects

A l : Adhesive Bonrfng of AlumWum AlloysAdhesive bonding offers the possibility of construct-ing light structures with beneficial mechanical prop-erties (e.g. good fatigue resistance). The surfacecondition is of primary significance for the bondperformance. The adhesive polymer links to theoxide formed on the adherend. This oxide is formedduring the pretreatment of the metal and its thicknessand morphology are dependent on the chemicalcomposition of the alloy.

Aluminium is especially well suited for adhesivebonding. In this project various such alloys arestudied. The project aims at clarifying the influenceof surface pretreatment on the joint durability. Thejoints are exposed in a humid atmosphere at elevatedtemperature and tested mechanically at regular inter-vals. The exposures in progress have lasted morethan 6 years. The surface state is studied by surfacesensitive techniques (small spot ESCA, Auger elec-tron spectroscopy, SIMS). The relationship betweenjoint durability, alloy composition and pretreatmentis being evaluated.Project leader Tekn.dr. Håkan Mattsson

A2: HydroxMe/Oxkle Formationon Pure Aluminium

Oxidation of Al in dry and humid atmosphere hasbeen studied by means of ESCA, Auger electronspectroscopy, EDX and Nuclear Reaction Analysis(NRA). NRA was used for determining the totalamount of oxygen bound in the oxide. The thick-nesses of the oxides formed on pure Al (99.998%)during exposure for 5h at 25CC and 250O°C are 15Åand 21.5Å, respectively. Using these data, the at-tenuation length of the electrons (photo and Augerelectrons) was determined. It was found that, usingAlKct X-ray source, the attenuation length of theA12p and Al2s electrons emitted from oxide andmetal are 18^ and 20Å, respectively. Quantitativesurface analysis of thin films can be performed usingthe data obtained.

During exposure to humid atmosphere (RH=80%)the oxide grows uniformly on pure Al (99 998%).The oxide becomes 22Å during exposure for oneweek. Exposure for longer times does not change theoxide thickness. On technically pure Al containinglow amounts of Fe and Si, localized corrosion takesplace around the intermetallic precipitates present on

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ENGINEERING METALS

the surface. Combined Auger and EDX analysesshow that the Fe- and Si-aluminides present on thesurface act as cathode areas. ESCA-studies of pureAl-hydroxide has shown that the surface hydroxideis not stable under UHV condition, and it almostimmediately decomposes to oxide and water. Thelayer decomposed is 7Å thick.

Interpretation of ESCA spectra recorded duringthe initial stages of hydration indicates that a timedependent space charge is set up in the oxide due todecomposition of water molecules adsorbed on thesurface oxide. A theoretical model explaining thisbehaviour by diffusion of AP+- and O2--ions isunder development.Project leader Professor Ingemar Olefjord.Student: tekn. lie. Anders Nylund

A3: Influence of Anodcally SegregatedElements on Passivity on Alloys

Surface analyses of stainless steels performed afterexposure to acid solutions have shown that thealloying elements Ni and Mo are enriched in theouter surface layers of the metal phase under thepassive film. Our hypothesis is that this enrichmentis due to the formation of an intermetallic thin film onthe surface and that the corrosion properties are, tosome extent, controlled by this layer.

The aim of this project is to produce syntheticintermetallic layers of the same composition as thoseformed on stainless steels and then study theirelectrochemical and corrosion behaviour. We havebuilt an UHV-sputtering equipment for depositionof metals and alloys on substrates. The thin filmsformed can be moved from the sputtering chamberto the instruments, ESCA, Auger, SIMS, EDX andSEM (Auger) without exposure to air. After charac-terisation of the film, the sample can be moved to anelectrochemical cell attached to the system. Theanalysis has shown that intermetallic bonds areformed between Ni and Mo during sputtering depo-sition. Ni and Mo act as electron donor and acceptorin accordance with Engel-Brewer theory.Project leader: Professor Ingemar Olefjord.Student: fil. kand. Susanne Börjesson.

A4: Pitting of Stainless SteelEarlier theories dealing with pitting of stainlesssteels have been built on the assumption that thecomposition of the so called passive film controls theproperties. Our research has shown that the compo-

sition and thickness of the film are almost independ-ent on the composition of the alloy and that anodicsegregation occurs as a result of active dissolutionduring passivation of stainless steel. The resultingsurface composition of the steel is radically differentfrom the bulk composition. Conditions seem tofavour formation of surface phases of intermetalliccompounds, which appear to control the kinetics ofactive dissolution and the composition of the passivefilm. We propose that the more complex stainlesssteel passivation may be due to the formation of aduplex kinetic barrier consisting of an outer oxidebased passive film and an inner intermetallic surfacephase with a higher lattice binding energy than thealloy.

The resistance against local corrosion attack isconsiderably increased for high Ni- and Mo-alloyedstainless steel. Surface analysis shows that Ni is notpresent in the passive film. Not even Mo is markedlyenriched in the film at potentials where high Mo-containing alloys show high performance. Thesealloying elements are enriched on the surface of themetal phase. Polarization diagrams show that thedissolution rate in the active range is much lower forthe high Ni-Mo alloyed steels compared to that of thelow alloyed steels, while the current in the passiverange is almost the same. This behaviour can beunderstood from the fact that the active dissolution iscontrolled by the surface metal composition, whilethe passive current is controlled by the passive film,the properties of which are about the same for thealloy categories. The increased pitting corrosionresistance of high Mo- and Ni-alloyed steels issuggested to be due to lower dissolution rate of aninitiated pit and thereby a more probable transforma-tion to the passive state.Project leader: Professor Ingemar Olefjord.Student: tekn. lie. Lena Wegrelius.

A5: Oxide OverlayersThe department participates in a consortium dealingwith "Oxide overlayers". All together nine depart-ments at five universities in Sweden are involved inthe project. The project is organised in four sub-projects. The aim of our sub-project is to developoxide catalysts for NOX-reduction with low concen-trations of catalysis-promoting metallic elementssuch as Pt, Pd and Ru.


ENGINEERING METALS

Oxides containing La, Sr, Cu and Ru have shownactivity comparable with a commercial Pt/Rh auto-motive catalyst The department studies surfaceproducts formed during catalytic reactions and givessurface analysis support to the other participants inthe project. It has been shown that reduction of thecatalyst in hydrogen gives a reduction of the Cu/Laratio due to the agglomeration of the reduced Cu-species. To be able to obtain a catalyst with highefficiency it is necessary to find a way to spread theCu-compound over the entire surface.Project leader Professor Ingemar Olefjord.Student: civ.ing. Magnus Holmquist

Bl: Fracture Mechanisms in Metal MatrixComposites - Toughness and FatigueBehavior

Fatigue properties of alumina and silicon carbidereinforced aluminium AA6061 have been investi-gated with the matrix alloy being studied as a com-plement. The studies have concerned crack growthcharacteristics of long fatigue cracks, strain control-led fatigue, and initiation and growth of short cracks.Both composites have fatigue crack growth thresh-olds 60% higher than that of the matrix alloy. Thesefindings are quantified in terms of larger angularcrack deviations, less crack tip opening (smallerelastic moduli) and crack branching. The low frac-ture toughness of the actual composites correspondsto lower crack growth resistance at high stress inten-sity ranges.

In strain controlled fatigue, the composites haveshorter fatigue life than has the matrix alloy at largeplastic strain amplitudes. At small amplitudes, thereverse is true. Studies of crack nucleation andgrowth indicate that growth of individual non-inter-acting small cracks determines fatigue life of bothcomposites. Nucleation of cracks always occurs atouter surfaces depending on localised strain concen-tration as rationalised by FEM modelling.Project leader: Professor Birger Karlsson.Student: tekn. lie. Magnus Levin.

B2: Fatigue Crack Growthof Duplex Stainless Steels

This project consists of two parts: one study on thefatigue crack growth properties of duplex stainlesssteels, and one study on the mechanical properties ingeneral of a duplex stainless steel.

Experimentally produced duplex ferritic/aus-tenitic, so called tie-line alloys with ferrite contentsranging from 0 to 100% have been studied. Inaddition a commercial duplex stainless grade hasbeen studied. The fatigue crack growth propertieswere investigated in samples as received and in coldrolled conditions. The results indicate that the fatiguecrack growth threshold is highest in the ferriticspecimens, while austenite Has the lowest thresholdlevel, with duplex alloys ranging in between.Prestraining leads to a pronounced drop in fatiguethreshold for all variants, while the crack closureessentially is left unaffected. The results are ration-alised in terms of quantitative fractography datafrom fatigue crack surfaces.

The study on the commercial duplex grade SAF2205 (50% austenite, 50% ferrite) revealed a pro-nounced anisotropy in the tensile behaviour, yet inopposite directions for uniaxial tension and impactloading situations. The individual deformation be-haviour of the two phases in the duplex grade hasbeen studied, as has the influence of hardening dueto spinodal decomposition.Project leader Professor Birger Karlsson.Student: tekn. lie. Magnus Nyström.

Cl: Powder Meta'lurgical Turbine MaterialsMartensitic stainless steel produced by powdermetallurgical (PM) technique is currently used insteam turbine parts. In order to raise the workingtemperature and thus improve the energy efficiency,new modifications of PM martensitic steel are beingdeveloped (ABB Stal and ABB Powdermet).

The mechanical properties of PM material de-pend significantly on the reaction products presenton prior particle boundaries (PPBs) in the compactedmaterial. In this project, ESCA and AES are used forstudying the reaction products formed on powdersurfaces and interfaces during powder fabrication(atomization), consolidation (hot isostatic pressing)and high temperature use (creep testing). The objec-tive of the studies is to correlate the properties of thematerial with the surface and interfacial reactionswhich take place during the processing and use of thematerial.

Recent findings and developments of the projectare: analysis and modelling of surface reaction phe-nomena in atomization related to particle size; devel-opment of an improved method for AES depth

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profiling on powder and other irregular samples;observation of correlation between light elementsegregation (P, S) and cavities/rnicrocracks in creptmaterial.Project leader Docent Lars Nyborg.Student: civ.ing. Mats Norell.

C2: Metal Irfection Moulding From Metal andHardmetal Powder

The objective of this project within the program"Powder Technology 90" is to develop competenceand technique for injection moulding of metal andhardmetal parts. The project is carried out in closecooperation with the Swedish Ceramic Institute andthe Department of Polymer Materials. Initially,Anval AB, Höganäs AB and Götene Plast AB haveparticipated in the project. From 1993 the research isextended to injection moulding of hard metals, andSandvik AB will be the prime industrial participant.Our part in the project is to optimize the sinteringprocess, to perform mechanical testing of sinteredproducts and to analyse fracture surfaces of thesintered products using AES.

A feasibility study has proved that the partici-pants in the project possess knowledge and tech-niques to produce injection moulded components ofstainless steel. The processing route used was: mix-ing stainless steel powder with a wax-based binder,moulding; debinding in nitrogen at 500°C; sinteringin vacuum up to 125O°C. Both gas- and water-atomized austenitic stainless steel powder were usedas raw material. In the former case, good results areobtained: porosities in thin sections, 3 mm, and thicksections, 6 mm, were 6% and 12%, respectively. Themechanical properties obtained are comparable tothose of conventionally produced stainless steel.Water-atomized powders give higher porosity, 15%and 24% in the thin and thick sections, and themechanical properties obtained are therefore poor.Project leader: Professor Ingemar Olefjord.Student: civ.ing. Anna Warren.

C3: Surface Cleaning of High Alloy Steel PowderThe mechanical properties of high alloyed steelpowder depend to a significant extent on the reactionproducts on prior particle boundaries (PPBs) in theconsolidated material. These reaction products arisefrom the surface reactions which take place duringatomization, powder handling and consolidation.

The reaction products can be limited by controllingcurrent powder fabrication and consolidation proce-dures. However, further improvement in materialperformance and development of new high qualityalloys require even higher surface cleanliness ofpowder than thai obtainable today.

The aim of this project is to study and developimproved methods for surface cleaning of high alloymetal powder. Especially, studies concerningdegassing, powder handling and surface oxide re-moval are carried out. Atomized powder is charac-terized using ESCA and AES both before and aftervarious heat treatments in vacuum or reducing gas.Mass spectrometry will also be used in order toestablish reaction schemes during the thermal treat-ment of powder. The materials studied are consoli-dated (hot isostatic pressing) and the effect of PPBreaction products on the mechanical properties areevaluated. The project is carried out in cooperationwith Swedish PM industry within the program"Powder Technology 90".Project leaden Docent Lars Nyborg.Student: tekn. lie. Thomas Tunberg.

C4: Influence of Pores and Precipitateson the Mechanical Properties ofPowder Metallurgical Steels

The present project concerns the influence of poregeometry and precipitates on the mechanical pro-perties of powder metallurgical steels. Ferritic andaustenitic, gas atomized powders compacted to vari-ous densities are studied. The reaction products onpore surfaces and prior particle boundaries (PPBs) inconsolidated material are analysed (TEM/STEM/AES). The mechanical properties are characterisedand related to the pore geometry, grain structure, andPPB-precipitates. In the investigation on mechanicalproperties, emphasis is placed on cyclic deforma-tion, low cycle fatigue and fatigue crack growth.A key role is placed on quantitative fractography.Thus, the mechancial behaviour and the fractureprocesses in particular will be related to themicroanalytical results. By this means, informationis gained on how processing of powder and consoli-dation affect the resulting mechanical behaviour.Project leader: Professor Birger Karlsson.Student: civ.ing. Ulf Lindstedt


ENGINEERING METALS

01: Development of Iran AiuminMesfor High Temperatures

Iron aluminidcs based on Fe3Al and FeAl arc con-sidered as candidates for structural applications atelevated temperatures (up to 650°C) because ofexcellent oxidation and sulphidation resistance, goodstrength comparable with available heat resistantstainless steel and relatively low density and cost.However, further extensive research is required toachieve an optimum combination of room and el-evated temperature properties. The prime objectiveof this project is to establish such optima by applyingprinciples of alloy design. The project includes thefollowing investigations:- Effect of alloying additions (eg. O , B, Mo, Ti, Si)

on mechanical properties of F^Al-base materialThe aim is to improve our understanding ofalloying principles of Fe3Al-alloys. The mate-rials studied are prepared by powder metallur-gical techniques such as hot isostatic pressing.

- Industrially produced alloys with variouscompositions are fabricated by using vacuumhot extrusion.

The materials studied are characterized with opticalmicroscopy, SEM/EPMA, TEM/EPMA and SAM.The mechanical properties at room and elevatedtemperatures are tested.Project leader. Docent Changhai Li.Student: berg.ing. Patrik Svensson

02: SIHclde* as Potential Structural Materialsfor High Temperature Applications

Silicides are very attractive intermetallic materialsfor use at high temperature because of their usuallyhigh melting temperatures and excellent resistancetohigh temperature corrosion. However, their tough-ness andductility at ambient temperature are low. Toovercome this problem, the following three ap-proaches are investigated.- In-situ composite concept to create a uniform

dispersion of fine particles in the intermetallicmatrix.

- Modification of crystal structure by alloyingdesign based on electron theory. The idea is toobtain high lattice symmetry and therebyimprove toughness and ductility.

- Partially disturbed bonding between siliconand metal atoms.

The investigated silicides are prepared by using themelt-spinning process. X-ray diffraction, SEM/EPM A, TEM/EPMA and SAM are used for micro-structural and interfacial characterization.Project leader. Docent Changhai Li

D3: Deformations and Fracture of StructuralCeramics under Tensile Uad Between20andl500°C

The objective of this project is a fundamental studyof deformation and fracture mechanisms in struc-tural ceramics both at ambient and high tempera-tures. The project is carried out by participants fromthree differentinstitutes(AdvancedCeramicGroup)providingauniquecombinationofexpertise: process-ing at the Swedish Ceramic Institue; microstructuralanalysis at the Department of Physics; mechanicaltesting at the Department of Engineering Metals.

Three significant features of the project are:- Deformation and fracture mechanisms are

carried out under precisely controlled tensileloading.

- The deformation and fracture mechanisms arestudied using advanced microanalytical techni-ques including analytical transmission electronmicroscopy.

- The materials studied, chosen to representvarious types of ceramic microstructures, areall produced in Sweden, one of them beingprepared in the laboratory of the participants ofthe Advanced Ceramic Group. This ensuresthat the materials and their preparation are wellcharacterized.

Project leader. Tekn.dr. Jonas Wasén.Student: tekn. lie. Thomas Hansson

D4: Metal/Ceramic Brazing for HighTemperature Applications

The achievement of good bonding between ceram-ics and metals by metallic brazing requires a goodunderstanding of the physico-chemical processesinvolved, such as wetting and possible chemicalreactions between the braze alloy and the surface tobe brazed; this is the subject of the research.

The wetting of silicon nitride with pure metals aswell as selected alloys has been studied. The studyalso included the superalloy Incoloy 909 as sub-strate. As little as 2 wt% Ti was found to be active inpromoting the wetting of silicon nitride and Incoloy909 by an Ag-28wt%Cu eutectic alloy.

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ENGINEERING METALS

The studies of wetting with the active Ag-

35wt%Cu-1.75wt%Ti have been extended to other

ceramics and Ni-base alloys. Relationships between

wettability and the observed interf acial reactions are

examined. It is concluded that the wettability is not

determined directly by the degree of reactivity but

rather by the wettability of the reaction layer formed

between braze and substrate.

The wetting on ceramics by Ni-based brazes was

generally poor. Some of the ceramic substrates re-

acted strongly with Ni. However, Si3N4 and AI2QJ

did not react and might therefore be used with this

type of braze after further development to improve

wetting.

Project leader Professor Richard Warren, docent

Lars Nyborg. Student: civ.ing. Maria Holmström

Publications

Ph.D. DissertationsJonas Wasén: "Fatigue crack growth and fracture in steels",January 1989.

Hakan Mattsson: "Oxidation of titanium in aqueoussolutions", January 1990.

Lennart Ljungberg: "Joining of ceramics to metals bybrazing", June 1992.

Sven Bengtsson: "Short alumina fibre reinforced alu-minium alloy composites", June 1992.

Licentiate DissertationsUlla Rilby: "Surface treatment for joining of aluminiumalloys", February 1989.

Lars Bjomkvist: "Passivation of chromium", May 1989.

Anders Nylund: "Surface analysis of rapidly solidifiedaluminium powders", June 1989.

Sven Bengtsson: "Short alumina fibre reinforced alu-minium alloy composites", September 1990.

Magnus Ixvin: "Fatigue crack growth properties of a SiC/aluminium composite material", September 1990.

Thomas Hansson, "Fracture of whisker reinforced andpaniculate ceramic composites", September 1991.

Lena Wcgrclius, "Surface analysis of stainless steels",March 1992.

Magnus Nyström. "Fatigue crack growth of duplex stain-less steels", March 1992.

Thomas Tunberg, "Surface reactions during atomizationand sintering of austcniuc stainless steel". May 1992.

Diploma worksBjörn Flink: "Spray deposition of stainless steel for nuclearpiant applications", 1989.

Kaj Eriksson, Thomas Tunberg: "Squeeze casting ofaluminium oxide composite", 1989.

David deVal: "Spot welding of steel sheet with Y AGlaser", 1989.

Jonas Adolfsson, Cecilia Askling: "Crack propagation insuper waspaloy - effect of frequency and exposure time inhydrogen", 1989.

Cecilia Norrby: 'Technical evaluation of alternatives tohcxavalentchromatizing", 1989.

Jörgen Johansson: "Non-destructive testing of metal andceramic matrix composites", 1989.

Jonas Wigforss, Henrik Ahlrén: "Industrial laser cutting ofaluminium polymer fibre composites", 1989.

Lars Hammar "Erosive corrosion of plain carbon and lowalloy steel", 1989.

Stefan Larsson: "The use of XPS and Auger to analyse thecarbon content of steel", 1989.

Ulla Boman: "Optimization of autoclave hardening cyclefor fabrication of carbon fibre/epoxy composites", 1989.

Mats Delin: "Thermally sprayed layers with WC-Co forhigh erosion resistance", 1990.

Henrik Dahlquist: "Induction hardcnability of variousmicrostructures", 1990.

Åsa Svensson: "Influence of pores and microstructure onfatigue fracture in aluminium alloys SS 4251 and SS 4253",1990.

Katarina Boustrdt: "Galling mechanisms - a basic study",1990.

Leo Tiid: "Effect of blasting process and oxide formationon adhesion of thermally sprayed layers", 1990.

Camilla Orrhult: "Case hardening of bearings - relationsbetween material properties and imposed stresses", 1991.


ENGINEERING METALS

Paula Eriksson: "Electrically conducting Si3N4-TiN-composites", 1991.

Peter Mellander: "Mechanical properties of high tempera-ture brazed nickel brazes", 1991.

Christina Eriksson: "Deformation och fracture initiation infibre reinforced aluminium", 1991.

Jonas Nilsson: 'Tensile fracture behaviour of AI2O3 fibrereinforced Al-Cu-alloys", 1992.

Jan Isidorsson: 'Titanium aluminides - an overview", 1992.

Jerker Fredholm: "High temperature aluminides - newmaterials for aircraft and space engines", 1992.

Mikael Soderholm: "Long time durability of cnoxy bondedaluminium joints", 1992.

Ingrid Mathillas: "Thermal fatigue and thermal chock ofSiC/S!r: composites", 1992.

Anders Pettersson, Hans Lyckc: 'Tubearing - increasedformability and endurance by carbonitriding a low carbonsteel", 1992.

Karin Schöön: "Stress analysis of a dircctionally solidifiedturbine blade", 1992.

Staffan Gråsjö: "The use of pre-coatcd/pre-lacquered sheetin car industry - properties during pressing, welding andpainting", 1992.

Nina Hclmrich, Helena Johansson: "Determination oftemperature profile in brake pads", 1992.

Olof Hcrvicu: "Controlled cooling as an alternative toisothermal annealing for two case hardening steels", 1992.

Magnus Holmquist: "Carbon/carbon composites for use athigh temperatures", 1992.

Roland Karlsson, Ulf Lindstedt: "Feasibility study concern-ing powder metallurgical processing of bearing balls",1992.

Lisa Nilsson, "Wetting of ZtOi by a Ag-Cu-Ti braze", 1992

Reports and articles1. Wetting of silicon nitride with selected metals and

alloys, L. Ljungberg, R. Warren, Ccram. Eng. Sci.Proc., 10,1989, pp. 1655-1666.

2. Surface analysis of ultrasonically gas atomizedaluminium and aluminium powders, I. Olcfjord and A.Nylund, Int. J. Rapid Solidification,!, 1989, p. 271.

3. The true grain size distribution of a WC-Co alloy,J. Wasén and R. Warren, To be published in Mater.Sci. &Techn. 1989.

4. Experimental characterization and geometrical model-ling of fatigue fracture surfaces, B. Karlsson and J.Wasén, 7th Int. Conf. Fracture, 'Advances in FractureResearch*, eds. K. Salarna, K. Ravi-Chandar, D.M.R.Taplin, and P. Rama Rao, (Pergamon Press, Oxford,1989) pp. 3383-3390.

5. Fracture of whisker reinforced ceramics, R. Warrenand V. Sarin, Chapter in "Application of FractureMechanics to Composite Materials", ed. K. Friedrich,(Elsevier, 1989), pp. 571-614.

6. Oxide morphology on phosphoric acid anodizedaluminium alloys, U. Rilby, G. Wetter and I. Olefjord,to be published in J. of Adhesive Science and Tech-nology, 1989.

7. G. ii'iiion of powder surfaces during the atomizau'on ofnizh-alloyed steel, L. Nyborg, Metal Powder Report,^ , 1 9 8 9 ^ . 3 2 - 3 4 .

8. Surface analysis of adhesive-bonded Zn-coatcd steel,G. Wetter and I. Olcfjord, Proc. 5th SSMS, NewMaterials and Processes, eds. I. Hansson and H.Lilholt, (Danish Society for Materials, Copenhagen,1989) pp. 729-736.

9. Microstructural studies of 5-alumina fibre reinforcedaluminium and Al alloys, S. Bengtsson, C-H. Li and R.Warren, Proc. ICCM7, eds. Wu Yunshu ctal.,(Pcrgamon 1989) 2, pp. 607-612.

10. Intcrfacial microstructurc and fracture analysis ofAl2O3-fibrc/Al composites, C-H. Li, S. Bengtsson, R.Warren, G. Dunlop and I. Olcfjord, Proc. 5th SSMS,eds. I. Hansson and H. Lillholt, (Danish Society forMaterials, Copenhagen, 1989) pp. 397404.

11. High temperature fracture at SiC whisker reinforcedalumina, L.X. Han, T. Hansson, S. Surcsh and R.Warren, Proc. 5th SSMS, eds. I. Hansson and H.Lillholt, (Danish Society for Materials, Copenhagen,1989) pp. 287-294.

12. Surface reactions during the hot isostatic pressing of12%Cr steel, L. Nyborg, Proc. 5th SSMS, NewMaterials and Processes, eds. I. Hansson and H.Lilholt, (Danish Society for Materials, Copenhagen,1989) pp. 485492.

13. Reactions between SiC>2-bindcr and matrix in 8-AI2O3/Al-Mg composites, C-H. Li, L. Nyborg, S. Bengtsson,R. Warren and I. Olefjord, Proc. Conf. IPCM, Ed.Jones, (Bultcrworths, 1989) pp. 253-257.

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14. lnicrcomparison of surface analysis of thin aluminiumoxide films, I. Olefjord, HJ. Maihicu and P. Marcus,Surf. Interface Anal., J5_, 1990.

15. Microstnicture and properties of squeeze cast aluminafibre reinforced aluminium composites, R. Warren,COST 504 Report.

16. Titanium exposed in water-saturated bentonite clay:exposures ranging up to six years H. Mattsson, SKBTechnical Report, 1989.

17. Electrochemistry of chromium in acidic chloridesolution, L. Bjönkvist and I. Olefjord CorrosionScience, 22,1991, p. 231.

18. Surface analysis of passive state, I. Olefjord and L.Wcgrelius, 6th Int Symp. on Passivity, Sapporo,Japan, 1989, in Corrosion Science, 21,1990, p. 89.

19. Theoretical calculation of the inverse logarithmic oxidegrowth law on titanium, H. Mattsson, to be publishedin Corrosion Science 1990.

20. Properties and metallurgical aspects of tungsten-wirereinforced metals, R. Warren, Chapter XVIII in "Themetallurgy of doped/non-sag tungsten", ed. E. Pink andL. Barta, (Elsevier, Barking, England, 1989).

21. Metal matrix composites for structural applications, R.Warren, Chapter in Advanced Materials TechnologyInternational 1990.

22. Fibre reinforced aluminium and supcralloy-bascdcomposites, R. Warren, Chapter in Advanced MaterialsTechnology International 1990.

23. Analysis of oxide formed on Ti during exposure inbentonite clay; I. The oxide growth H. Mattsson and I.Olefjord, Werkstoffe und Korrosion, 4J., 1990, p. 383.

24. Analysis of oxide formed on Ti during exposure inbentonite clay; II. The structure of the oxide, H.Mattsson, C.H. Li and I. Olefjord, Wcrkstoffc undKorrosion, 4i, 1990, p. 478.

25. ESCA calibration studies of titanium oxides andtitanium hydride, H. Mattsson and I. Olefjord, to bepublished in Surf. Interface Anal.

26. Surface characterisation of PM martensilic steel, L.Nyborg, M. Norell and I. Olefjord Proc. World Conf.Powder Metall. PM90, (The Institute of Mclals,London, 1990), 2, pp. 364-369.

27. lntcrfacial interactions in fibre reinforced Al- and Mg-alloys, R. Warren and C-H. Li Proc. ICCI-III, cd.Ishida, (Elsevicr, Barking, England, 1990), pp. 583-599.

28. A novel method for identifying phases formed inbrazed and soldered joints, L. Ljungberg, R. WarrenandC-H.Li,J.MaLSci. Letters, 2,1990, pp. 1316-1318.

29. Influence of cold deformation on the near-thresholdfatigue crack growth in fine-grained DP-slccls, J.Wasén and B. Karlsson, Proc. 4th Intern. Conf. Fatigueand Fatigue Thresholds, Fatigue '90, ed. H. Kitagawaand T. Tanaka, (Engineering and Materials AdvisoryServices, Warley, 1990) pp. 1437-1443.

30. The relation between fracture surface geometry andcrack closure in fatigue, J. Wascn and B. Karlsson,Proc. 4th Intern. Conf. Fatigue and Fatigue Thresholds,Fatigue '90, Ed. H. Kitagawa and T. Tanaka, (Engi-neering and Materials Advisory Services, Warley,1990) pp. 1289-1294.

31. Surface analysis of water-atomized austcnitic stainlesssteel powder, L. Nyborg, T. Tunberg, P.X. Wang and I.Olefjord, Proc. World Conf. Powder Metal!. PM90,(The Instituc of Metals, London, 1990), 2, pp. 199-203.

32. Reaction products on metal powder surfaces andinterfaces, L. Nyborg, M. Norell, T. Tunberg and I.Olefjord, Proc. Colloq. Controlling the Properties ofPM Parts through their Microstructurc, (.FrenchMetallurgical Soc., Paris, 1990), pp. 25.1-25.6.

33. Geometrical quantification of fracture surfaces and itssignificance in fatigue studies, B. Karlsson and J. Wasén,Proc. 4th Intern. Conf. Fatigue and Fatigue Thresholds,Fatigue '90, cd. H. Kitagawa and T. Tanaka, (Engi-neering and Materials Advisory Services, Warley,1990), pp. 279-284.

34. Fatigue crack growth in a microduplex stainless steel,J. Wasén, B. Karlsson and M. Nyström, Proc. 4th Intern.Conf. Fatigue and Fatigue Thresholds, Fatigue '90, cd.H. Kitagawa and T. Tanaka, (Engineering and Materi-als Advisory Services, Warley, 1990) pp. 1167-1172.

35. The fatigue crack growth characteristics and ils relationto the quantitative fractographic appearance in apaniculate AI 6061/SiC composite material, M. Levin,B. Karlsson and J. Wasén, TMS Publication "Funda-mental relationships between microstructurc andmechanical properties of metal matrix composites",(TMS, Warrcndalc, Pennsylvania, 1990) pp. 421439.

36. Influence of prcstrain and ageing on the ncar-ihrcsholdcrack growth in fine-grained dual-phase steels, J. Wasénand B. Karlsson, Intern. J. Fatigue,U, 1989, pp. 395405.

37. Design requirements - Materials properties: A basis formaterials selection, U. BcngLson, B. Karlsson and D.Parsmo, Proc. 2nd Intcm. Symp. Materials PropertyData, Orlando, Nov. 1989, (ASTM STP 1106,1991),pp 230-251.


ENGINEERING METALS

38. Surface composition of stainless steel during activedissolution and passivation, I. Olefjord and C. Clayton,Iron and Steel Inst Japan Int., 31,1991, p. 134.

39. Microstruclurc and fracture behaviour of SiCw rein-forced alumina, T. Hansson, R. Warren and J. Wasén,1 lth Risö Symposium Met. Mads. Sci., (Risö NationalLab.,1990), pp. 327-332.

40. Surface characterization of a rapidly solidifiedA^Mn^sCr powder before and after hot extrusion,Nylund and I. Olefjord, Proc. 7th Int. Conf. on RapidQuenching of Materials, Stockholm 1990, in Mat. Sci.and Eng., Al i i ,1991, pp. 1139-1145.

41. Degassing of USGA-atomized Al5Mn6Cr powder afterexposure to a humid atmosphere, A Nylund and I.Olefjord, Proc. 7th Int. Conf. on Rapid Quenching ofMaterials, Stockholm 1990, in Mat. Sci. and Eng.,A134.1991 .DP. 1225-1228.

42. Anisotropy effect in the fracture behaviour of a uniaxialhot pressed SiC whisker reinforced ceramic composite,T. Hansson, R. Warren and J. Wasén, Proc. ECF-8,(EMAS, Warley, UK, 1990), pp. 560-564.

43. Fractographic aspects on fatigue crack growth inporous sintered steels, B. Karlsson, J. Wasén and I.Bcrtilsson, Proc. 8th Europ. Conf. Fracture, ed. D.Firrao, (Engineering and Materials Advisory Services,Warley, 1990) pp. 421-426.

44. Fatigue crack growth properties of SAF 2205, J. Wasén,B. Karlsson and M. Nyström, Proc. Mechanical Proper-ties of Stainless Steels, eds. H. Nordberg and K.Fernhcden,(Jemkontoret, Stockholm, 1990) pp. 122-135.

45. Paniculate ceramic matrix composites, R. Warren andV. Sarin, Chap. 6 in 'Introduction to Structural CeramicComposites', ed. R. Warren, (Blackie, Glasgow, 1991).

46. The influence of SiC particle distribution and »restrai-ning on fatigue crack growth rates in an aluminium AA6061/SiC composite material, M. Levin and B.Karlsson, Materials Science and Technology, 2,1991,pp. 596-607.

47. The mechanical properties of a duplex stainless steelM. Nyström, B. Karlsson and J. Wasdn, Proc. Mechani-cal Properties of Stainless Steels, eds. H. Nordberg andK. Fcrnheden,0emkontoret, Stockholm, 1990) pp. 70-87.

48. Surface product formation during water atomisationand sintering of austenitic stainless steel powder, L.Nyborg, T. Tunberg and P.X. Wang, Metal PowderReport, Nov. issue. 1990, pp. 751 -754.

49. Influence of surface oxide character on the strength andstability of steel-epoxy joints, G. Wetter, L. Kozma andI. Olefjord, to be published in Scand. J. of Metallurgy.

50. XPS - Qualitative and quantitative aspects, I. Olefjord,Invited lecture. Proc. The Application of SurfaceAnalysis Methods to Environmental/Material Interac-tions, eds.D.R. Baer, C.R. Clayton and G.D. Davis,(".' he Electrochemical Soc. Corrosion Div., Pennington,NJ., 1991), p. 2.

51. The influence of prcstraining and 475°C annealing onthe mechanical properties of a duplex stainless steel(SAF 2205), M. Nyström, B. Karlsson and J. Wasén,Proc. Stainless Steels '91, ed. K. Yokota, (The Iron Steeland Steel Institute of Japan, Tokyo, 1991), pp. 738-745.

52. A catalogue of stcreological characteristics of selectedsolid bodies, vol. 1, Polyhedrons, J. Wasén and R.Warren, (Chalmers University of Technology, 1991).

53. Surface analysis of four dental implant systems, I.Olcfjord and S. Hansson to be published in Int. J. ofOral and Maxillofacial Implants.

54. In-depth analysis of passive films on Fc-Cr alloy bypotential-modulated UV-visible reflection spectroscopy,N. Hara, I. Olefjord and K. Sugimoto, Proc. Int. Conf.on Stainless Steels, 1991,Chiba, ISU.

55. Wetting and interactions between selected ceramicsand Ni-base braze alloys, M. Holmström, L Ljungberg,A. Warren and R. Warren, Proc. 4th Int. Symp. CeramicMaterialsand Components for Engines, cd. R. Carlsson,(Elscvicr, Essex, England, 1991).

56. Principles of preparation of ceramic composites, R.Warren and R. Lundberg, Chap. 3 in 'Structural CeramicComposites', ed. R. Warren, (Blackic, Glasgow, 1991).

57. Fundamental aspects of the properties of ceramic matrixcomposites, R. Warren, Chap. 4 in 'Svuclural CeramicComposites', ed. R. Warren, (Blackie, Glasgow, 1991).

58. Overview, Chap. 1 in 'Structural Ceramic Composites',R. Warren, Ed. R. Warren, (Blackie & Son, Glasgow,1991).

59. Hardness friction and fracture behaviour of AI2O3-SiCw up to 1500cC, C.A. Brookes, P. Green, T.Hansson and R. Warren, J. Hard Materials, 1(3), 1991,pp. 183-199.

60. Fracture toughness anisotropy and toughening mecha-nisms of a hot-pressed alumina reinforced with SiC-whiskers, T. Hansson, R. Warren and J. Wasén, to bepublished in J. Amcr. Ccram. Soc.

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61. Thickness determination of surface oxides on metalpowder by AES depth profiling, M. Norell, L. Nyborg,T. Tunberg and I. Olefjord, Surf. Interface Anal., 12,1992, pp. 71-76.

62. Surface studies of powder metallurgical stainless steel,L. Nyborg, M. Norell and I. Olefjord, Surf. InterfaceAnal., J2,1992, pp. 607-614.

63. Fatigue crack growth of duplex stainless steels, M.Nyström, B. Karlsson and J. Wasén, Proc. DuplexStainless Steels '91, Les Editions de Physique, (LesUlis Cedex, France, 992) pp. 795-802.

64. Iron aluminides - intcrmetallic materials for high-temperature use, C-H. Li, R. Warren and I. Olefjord,Report 651/91, Dep of Engineering Metals, 1991.

65. Low cycle fatigue of discontinuously reinforced metalmatrix composites, M. Levin and B. Karlsson, Proc.5th European Conf. on Composite Materials, eds. A.R.Bunsell, JJ\ Jamct, and A. Massiah, (Bordeaux, April1992) pp. 561-569.

66. Surface reactions during production of PM austeniticstainless steel, L. Nyborg, T. Tunberg, I. Olefjord, C.X.Liu, P.X. Wang, Swedish-Chinese symposium, Oct.,1992, Sanya, China.

67. Wetting and chemical interactions of selected ceramicsand superalfoys with a Ag-Cu-Ti active braze alloy, L.Ljungberg, K. Warren and L. Pejryd, to be published.

68. High temperature fracture of a SiC whisker reinforcedalumina in air and vacuum, T. Hansson, A.H. Swanand R. Warren, to be published.

69. Determination of attenuation lengths of photoelcc tronsin Al and Al oxide by angledependcnt X-ray photo-electron spectroscopy, P. Marcus, C. Hinnen and I.Olefjord to be published in Surf. Interface Anal.

70. Electrochemical and surface analysis of stainless steelsexposed to hydrochloric acid, L. Wcgrelius, to bepublished.

71. Microstructure of Ag-Cu-Ti brazed joints betweenS13N4 and a nickel alloy, L. Ljungberg, L. Pejryd andR. Warren, to be published.

72. Enhanced vacuum sintering of water-atomizedaustenitic stainless steel powder by carbon addition,Proc. of 1992 World Conf. on Powder Metall. "Ad-vances in Powder Metallurgy and Paniculate Materi-als", (MPIF, Princeton, NJ., 1992) pp. 383-395.

73. Fracture strength testing of fibres with variablediameter and length - 5-alumina fibres, A.S. Kim, S.Bengtsson and R. Warren, to be published.

74. Tensile behaviour of squeeze cast and forged shortalumina fibre reinforced AA 6061, S. Bengtsson and R.Warren, to be published.

75. Reactions during atomization of martensitic steel, M.Norell, L. Nyborg and I. Olefjord, Proc. of 1992 WorldConf. Powder Metall. "Advances in Powder Metallurgyand Paniculate Materials", (MPIF, Princeton, NJ.,1992) pp. 41-54.

76. Forming of components starting from metal powder, I.Olefjord, NUTEK-report, project 91-00527,1992.

78. Oxidation of Aluminium in dry and humid atmospherestudied by ESCA and SEM, A. Nylund and I. Olefjord,to be published in Surf. Interface Anal.

79. ESCA analysis of AI2O3 formed on Al under spacecharging conditions, I. Olefjord and A. Nylund, to bepublished in Surf. Interface Anal.

80. Silicides as potential structural materials for hightemperature applications, C.H. Li, R. Warren, I.Olefjord and L. LÉstrade, Report 680/92, Dep. ofEngineering Metals.

81. Fatigue behaviour of a Saffil reinforced aluminium alloy(AA6061), M. Levin and B. Karlsson, CompositesJanuary 1993.

82. Crack initiation and growth during low cycle fatigue ofdiscontinuously reinforced metal matrix composites,M. Levin and B. Karlsson, 1992, Submitted to Intern.J .Fatigue.


Microscopy and Microanalysis

Research SummaryResearch in the Division is concerned with develop-ing and improving understanding of the fine scalemicrostructure of technologically important materi-als. Of importance here is understanding how micro-structure, down to atomic scale, can be manipulatedby variation of process variables such as composi-tion, solidification rate, sintering schedules, deposi-tion conditions and heat treatment. Of equal impor-tance is the role which microstructure plays in deter-mining materials properties.

The main research tools that have been used areanalytical electron microscopy and atom-probe fieldion microscopy. Use has also been made of SIMSand Scanning Auger Spectroscopy. Scientists andresearch students within the Division have collabo-rated with many industries and other research groups,both within and outside Chalmers, in order to obtaina complete picture of relationships between process-ing conditions, microstructure and properties.

Types of materials which have been investigatedinclude: cemented carbides, CVD coatings, highspeed steels, stainless steels, low alloy weld metals,cast aluminium alloys, rapidly solidified aluminiumalloys, copper alloys, cast iron cylinder liners,zircalJoy, silicon nitride, zirconia toughened ceram-ics, metal matrix composites, ceramic composites,zinc oxide varistors, GaAs hetero-structures andhigh-Tc superconductors. In all cases the emphasishas been upon a fundamental understanding of micro-structure, its manipulation and its importance indetermining the properties of materials

StaffSenior MembersAnders ThölénHans NordenHans-Olof AndrénLena FalkColette O'MearaEva OlssonKrystyna Stiller

Graduate StudentsJosé AlarcoHåkan BjörklundCai GuangjunMats HalvarssonMaria Knutson-WedelAnders KvistZonghe LaiPer LindahlRos-Marie LundhLars LundinLars MattssonBengt OlssonHu QiuhongBertil StenbomMattias ThuvanderBoel Wadman

Technical StaffEduard GuttenbergEva-Britt Sjoqvist

SecretaryMarita Ahlkvist

professort.f. professordocentdocenttekn. dr.tekn. dr.tekn. dr.

(B. Se.)(civ.ing.)(M. Se.)(civ. ing.)(civ.ing.)(civ.ing.)(M. Se.)(civ. ing.)(civ. ing.)(civ. ing.)(civ.ing.)(civ. ing.)(M. Se.)(fil. kand.)(civ ing)(tekn. lic.)

AddressDepartment of PhysicsChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31 772 3206Fax+46 31 165176

Major Instrumentation• Anew200kVTEM/STEMwithaFEG(field

emission gun)will be installed during 1994• 200kVTEM/STEM/EDX: JTOL2000FX• lOOkVTEM: two Philips EM 300• 100 kV STEM/EDX/EELS: VG HB501 (This

instrument belongs to Volvo but the Divisionhas full use of it.)

• SEM/EDX: CAMSCAN S4-80DV

228 THE CENTRE FOR

MICROSCOPY AND MICROANALYSIS

• X-ray diffractometer• Atom-probe field ion microscope (A-PFIM)• Imaging atom-probe field ion microscope (A

second A-P FIM is under construction.)• Specimen preparation:

diamond cutting machinesspark cutting machinegrinding, polishing facilitieselectro-chemical polishing lab3 ion beam thinning machines

• Fully equipped photo-processing labContact persons for microstructural investigations:Hans Norden,Metals: Hans-Olof Andrén and Krystyna Stiller,Ceramics: Lena Falk and Colette O'Meara,Electric materials: Eva Olsson.


A: Electron Microscopy Studies of MaterialsParticipants: José Alarco, Håkan Björklund, LenaFalk,CaiGuangjun, Mats Halvarsson, MariaKnutson-Wedel, Lai Zonghe, Ros-Marie Lundh, Lars Lundin,Lars Mattsson, Hans Noidén, Eva Olsson, BertilStenbom, Krystyna StillerCollaborators: Avesta AB, Avesta; Elektrolux Mo-tor AB; Swedish Ceramic Institute, Göteborg; De-partment of Applied Physics, CTH; Department ofEngineering Metals, CTH; Departmentof InorganicChemistry, University of Stockholm; HeraeusAsalmaz Katalysator Gmbh, Swedish Institute forMetals Research, Stockholm; Norsk Hydro,Porsgrunn, Norge; Sandvik Hard Materials, Stock-holm; AB Sandvik Steel, Sandviken; StatensTeknologiska Institut, Oslo, Norge; SECO ToolsAB, Fagersta, AB Volvo, Göteborg; Volvo TU,Göteborg; Volvo Flygmotor, Trollhättan;

B: Atom Probe Field lon Micioscopyof Materials

Participants: Hans-Olof Andrén, Cai Guangjun, HuQiuhong, Anders Kvist, Lai Zonghe, Per Lindahl,Lars Lundin, Hans Norden, Krystyna Stiller, BoelWadmanCollaborators: ABB Atom, Västerås (P Rudling),ABB Powdermet, Surahammar (A Salwén), ABBSTAL, Finspång (S Fällman), Avesta AB, Avesta(M Liljas), Dalhousie University, Halifax, Canada

(H Kreutzer), ESAB AB, Göteborg (L-E Svensson,L Karlsson), Institute of Theoretical and Experi-mental Physics, Moscow (A Suvorov), Max-PlanckInstitut fur Metallforschung, Stuttgart (H Fisch-meister, S Karagöz), AB Sandvik Coromant, Stock-holm (C Chatfield, U Rolander), AB Sandvik Steel,Sandviken (T Andersson, A-L Lundström), SecoTooisAB,Fagersta(HJonsson,TMainert),StudsvikAB, Nyköping (K Norring), Vattenfall Bränsle,Stockholm (H Pettersson).

Research Projects

A: Electron Microscopy Studiesof Materials

Al : SI3N4 Based Ceramic MaterialsFormed by HIP

Work carried out within this project has demon-strated that it is possible todesign the microstructureof a Si3N4 ceramic material to a given combinationof properties. The materials have been formed byglass encapsulation followed by hot isostatio press-ing (HIP) at Sandvik Hard Materials. Particularattention is paid to the effect of different types ofmetal oxide sintering additives, as well as to howamount and type of oxide sintering aid control grainmorphology and intergranular microstructure of theSJ3N4 ceramic. The results from analytical electronmicroscopy (SEM/TEM/STEM/EDX) and x-raydiffractometry are related to mechanical properties,i.e. fracture toughness, room temperature and hightemperature strength and hardness.

References: 5,7,9,11,12,15,17,18,21,23

A2: Microstructure and Oxidation Behaviour ofSI3N4/Z1O2, Composite Ceramic Materials

S12N4/71O2 composite ceramic materials have ahigh potential for improved mechanical properties,e.g. toughness and strength, at both high and lowtemperatures, as compared to conventional "singlephase" SJ3N4 materials. The fine scale microstruc-tures of Si3N4/ZrO2 ceramics formed by differentprocesses are characterized in detail by a combina-tion of analytical electron microscopy (SEM/TEM/STEM/EDX) and x-ray diffractometry. Particularattention is given to the effect of other, simultaneous,oxide additions upon the internal structure of the



ZrC>2 grains and the intergranular microstructure.The microstructures of the different composites inthe as-sintered state as well as after various oxidationtreatments are correlated to fabrication process andmechanical and chemical properties.

References: 2,3,4,8,10,14,24,25

A3: Whisker Reinforced SI3N4and AI2O3 Ceramics

Whisker reinforced ceramics may offer improvedtoughness and strength. The aim of this work is todevelop an improved understanding of the deve-lopment of the fine scale microstructures of Si3N4

and AI2P3 ceramics reinforced by different types ofSiC whiskers. Particular attention is given to matrixmorphology and matrix/whisker interface and thesefeatures are related to variables in the formationprocess. Quantitative microscopy is used to charac-terize the effect of different additives upon matrixgrain size and shape, and the different microstruc-tures are related to the mechanical properties of theceramics.

References: 16,19,20,26

A4: Liquid Phase Sintered SIC CeramicsAddition of metal oxides e.g. AI2O3 and/or Y2O3makes it possible to densify SiC by liquid phasesintering. This project is concerned with phase reac-tions during densification, and the relationship be-tween fine scale microstructure and physical proper-ties. The SiC ceramics are formed by pressurelesssintering or hot isostatic pressing.

A5: Mlcrostructural Investigation of Corrosion/Oxidation of Engineering Ceramics

Si3N4 and SiC ceramics are the most promisingcandidate ceramic materials for application in hightemperature chemically severe environments suchas heat engines, process equipment and cutting tool-set-ups. However, to date very little is known aboutmechanisms, kinetics or effects of chemical attackin ceramic materials. The aim of this work is toquantify (by XRD, SEM/TEM/STEM/EDX) theeffect of well controlled corrosion experiments onthe microstructure and thereby the mechanical pro-perties of S13N4 and SiC based materials. Specialattention is being given to identifying the mecha-nism^) of importance during corrosive attack ofthese ceramics.

References: 27-29

A6: Microstructural Development FollowingHeat Treatment of ZiOS^tyO Compositesand Y-SUU-ZrO* Glasses

A considerable improvement in the mechanical prop-erties of silicon based nitrogen ceramics can beachieved through the addition of small quantities ofstabilised Z1O2 particles to the ceramic matrix(dispersion toughening). This work examines themicrostructure of as sintered ZrO2-Si2N2O com-posites and Y-Si-Al-Zr-O-N glasses and their heattreated (N2 and air) products. The aim of the projectis to identify heat treatment conditions for ZrC«2-Si2N2O composites which avoid the formation ofcertain deleterious Zr-oxynitride phases and to exa-mine the effect of Z1O2 additions on the crystallisa-tion behaviour and products of Y-Si-Al-Zr-O-Nglasses.

References: 30

A7: Structural Deactlvation PhenomenaIn Heterogeneous Catalysis

Sintering of the noble metal particles is one of themajor cause for decreased efficiency of supportedexhaust catalysts. The influence of temperature,time and atmosphere have been investigated byTEM and CO-TDS for a Pt/Alumina catalyst. Theinitial sintering rate was found to be rapid in oxidativeatmospheres (O2, NO) compared to in inert or redu-cing ones (Ar, H2, CO). Different combinations ofnoble metals (Pt, Rh) and supports (Alumina, Ceria)will also be investigated.

References: 31-34

A8 Relations Between Processing Parameters,Micro Structure and Performancefor CVD Coated Cemented Carbides

Multi layer coatings (5-10 alumina layers) consist-ing of sub layers of pure (X-AI2O3 and K-AI2O3respectively, have been deposited in a hot wall CVDreactor. To nucleate and grow a desired aluminapolymorph in each layer, thin modification layerswere used between the alumina layers.

In this project the interfacial structure of themodification and the alumina layers are being stu-died. Features of the microstructure such as defects,pores at interfaces and orientation relationships arebeing characterised. The materials are examinedusingacombinationof XRD, SEM,TEM andEDX,although the major part of the analysis is carried outby TEM of cross section specimens.

References: 106-108

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A9: Microscopic Wear and DeformationMechanisms in Fretting

An all metal fretting rig of new design has beencompleted and mounted in an oil-free environmentin a vacuum chamber, where the ambient atmos-phere can be varied. Ni is being used as a modelmaterial and microscopic techniques including trans-mission electron microscopy (TEM) arc used tocharacterize the damage.

A preparation technique has been developed forTEM specimen where a plated layer is used toprotect the original fretting surface and also retainthe fretting debris. Using this method cross sectionspecimens can be prepared, which allow characte-rization of the subsurface structure from all fourdamage regions.- A: a central contact region, where sticking is

dominant- B: a transition region- C: a slip region- D: an outer region, where most of the debris is

collectedDislocation movement produces a nearly equiaxedcell structure in the central part of Region A, whereasthe cell structure becomes more elongated towardsthe edge. The length to width ratio of the cellsincrease in Region B and their orientation change.The initiation of fatigue cracks was observed here.A very fine scaled, elongated cell structure developsin Region C

AID: Election Microscopy Studiesof High Temperature Superconductors

The electron microscopy of the high temperaturesuperconductors is mainly concerned with epitaxialthin films. The aim of the research is to characterisethe fine scale microstructure and to relate it to thesuperconducting behaviour. Grain boundaries playan important role in determining the properties andspecial attention is therefore paid to both grainboundaries and other types of interfaces. The grainboundaries may act as weak links limiting the criticalcurrent density where the detailed behaviour of theindividual boundary dependson thefine scale micro-structure. Each basic study of a specific pheno-menon and each application requires a well definedboundary structure that can be fabricated repro-ducibly. In some studies it is necessary to avoid theformation of boundaries. In addition,most structuresrequires multilayer structures where the supercon-

ducting thin films are separated by layers that areeither metallic, semiconducting, or insulating. Theproperties of the thin layers are significantly influ-enced by the interfaces and the behaviour thus differsfrom that of bulk materials. The multilayers there-fore provide the possibility to control and modify thephysical characteristics. The microstructure is thekey to the understanding these structures. The micro-structures are studied as a function of fabricationparameters. The data provide a source of knowledgeforfuture need to control and to make new structureswith predetermined properties.

References: 36-62

B: Atom Probe Field Ion Microscopyof Materials

B l : Microstructure of Creep Resistant12XrChromfum Steels

A new class of creep resistant chromium steels,made by powder metallurgical methods, is at presentoeing developed for use at 600"C. The materialsstudied have been given different additions of thestrong carbide formers (Mo, W, V, and Nb). Thedominating mechanism of creep resistance in thesealloys is probably due to a fine precipitation of MC-type carbides. We are studying the microstructure oftwo alloys with different composition using atomprobe analysis and transmission electron microscopy,in particular the composition of very small preci-pitates.

References: 73,75,76

B2: Microstructure of Weld Metalin Chromium Steels

The microstructure of weld metal of chromium-molybdenum steels (5, 9 and 12% Cr) is beingstudied both as welded and after post-weld heattreatment at 750*C, using electron microscopy andatom probe analysis. The toughness of 12% Cr weldmetal may be rather poor because of precipitation oflarge carbides at phase boundaries. Attempts tomodify the composition of the weld metal did notdiminish precipita.ion; however introduction of anintercooling treatment to restrict the amount of re-tained austenite and its subsequent eutectoid de-composition was found to improve toughness con-siderably.

References: 88-92



B3: High Speed SteelsOur work on the microstructure of high speed steelshas continued with studies of overtempering at600*C in collaboration with Max-Plarick-Jnstitutefur Metallforschung in Stuttgart. The purpose was tosimulate the behaviour of high speed steel toolsduring service. For about 100 minutes the as tem-pered hardness remained high, although small M2Cprecipitates coarsened during this time. This re-markable hot hardness of high speed steels wasfound to be due to a second wave of precipitation ofextremely small (1.5 nm) MC particles on dislo-cations, acting as very efficient obstacles againstplastic deformation.

Our previous work on the microstructure of highspeed steels has been published, and a review of allour results on the detailed microstructure of highspeed steels has been made.

References: 71-74,77

B4: Duplex Stainless SteelsThe austenite phase in nitrogen containing duplexstainless steels was analysed with atom probe. Thelarge hardening effect of nitrogen additions wasfound to be due to nitrogen-molybdenum clusterformation in the austenite. Weld metal of duplexstainless steels was heat treated in the temperatureinterval 700-950'C, and the kinetics of the resultingprecipitation of intermetallic phases (s, R and c) wasstudied. It was found that the risk of embrittlementduring normal welding conditions was small. Asilicon containing duplex stainless steel having highstrength, good ductility and high corrosion resis-tance was found to contain small nickel-titaniumsilicides in the ferritic phase.

References: 68-70

B5: Microstructure and Corrosion of GrainBoundaries In Nickelbased Superalloys

The composition of grain boundaries in severalvariants of two Ni-based superalloys, Alloy 600 andAlloy 690, has been measured using atom probeanalysis and secondary ion mass spectrometry.Segregation of C and B was found both after manu-facture and after exposure to high purity water at365'C. Depletion of chromium was also observedclose to the grain boundaries, as well as grain bound-ary precipitates of the type M23Q, M(C,N) andM7C3. These findings are important for the under-standing of intergranular stress corrosion cracking

behaviour of the materials.References: 98-101

B6: Mechanisms of Zircaloy Corrosion in SteamIn Zircaloy (Zr-Sn-alloys with small additions of Fe,Cr, and sometimes Ni) intermetallic precipitatesform during manufacture, which leads to a depletionof alloying elements in the matrix between preci-pitates. Using atom probe analysis we have meas-ured the extent of this depletion in materials withdifferent corrosion resistance in 400*C steam. It wasfound that depletion occurs extremely fast due to anunusually high diff usivity and a low solubility of Fe,Cr and Ni in Zircaloy. Thin foils of cross sections ofthe metal-oxide interface are at present being studiedin the transmission electron microscope, in order tounderstand the oxide growth mechanisms.

References: 84-87

B7: Phase Composition in Cemented CarbidesThe microstructcre of one series of commercialcermets of the geneiu! formula (Ti, W, Ta) (C, N)-Ni-Co and two series of model cermet alloys arebeing studied in detail using atom probe, transmis-sion and scanning electron microscopy and X-raydiffraction. The first series of model alloys has thecomposition TiC - (0,10 and 20) vol.% TiN -10%Mo2C-(5andlO)%Ni-(10and5)%Coandisusedto study the effect of a mixed binder phase. With thesecond series we will study the occurrence of heavycarbo-nitrides; these alloys have the compositionTiC - 20 vol.% TiN - 15% Ni - (10, 20 and 30)%M02C or WC. All cermet materials have carbo-nitride grains with a core-rim structure, and thecomposition and compositional variation of theseand the binder phase reflect processes that take placeduring sintering (diffusion, dissolution, precipita-tion). The distribution of C and N is of particularinterest.

References: 78-82

B8: Ordering and Segregationin Hfgh-Tc Superconductors

The oxygen content of YBa2Cu3(>7_x superconduc-tors determines the superconducting properties. For0<x<0.5 a short rangeordering of oxygen is believedto occur on a very fine scale. We will study thisordering using atom probe microanalysis. Segrega-tion of oxygen and other atoms to grain boundariesin the material may also affect its properties consid-

232 THE CENTRE FOR


erably, as the coherence length is only 0.3-1.5 nm.The boundaries will also be studied with atom probe.As a first step, materials with controlled oxygencontent and a low porosity (as required for atomprobe analysis) are being prepared in collaborationwith Department of Inorganic Chemistry at ChalmersUniversity. At the same time conditions are beingoptimised for quantitative analyses of HTC super-conductors in the atom probe.

References: 102,103

B9: Mlcroanafysls of Metal Contacts on GaAsRectifying (Schottky) contacts of Au and Ag ontoGaAs, as well as ohmic contacts of AuGe on GaAsare being studied in atomic detail with atom probe.On an oxidised surface, Au and Ag form islands ofpure metal, whereas on an atomically clean surface(prepared by field evaporation), Au forms an inter-mixed layer while Ag makes a sharp interface againstGaAs. In the case of AuGe contacts on an oxidisedsurface, gold islandscovered by aGe rich oxide layerwas formed. After heat treatment at 450"C a thin(6 nm) diffusion zone of high Ge concentration (3at%) into GaAs was observed. Ga was found todiffuse out through the gold layer and form an oxidefilm together with Ge.

References: 93-97

BIO: Radiation DamageEarlier work on heavy ion irradiation of W has beenpublished. In collaboration with the Institute ofTheoretical and Experimental Physics in Moscowradiation enhanced solid solution and diffusion inTa-2%U is being studied.

References: 83

B l l : Grain Boundary Structureand Segregation In W

The terms grain boundary diffusion and pipe diffu-sion, respectively, are frequently used to describeenhanced diffusion effects but very little is knownabout the mechanisms behind these phenomena at amore fundamental leve1. The object of this project istherefore to study grain boundary segregation anddiffusion on an atomic level and in particular toinvestigate the correlation between these effects andthe related grain boundary structure.

Pure W doped with small amounts of Ni or Pd isused as a model material. It is well known that thepresence of small amounts of these elements drasti-

cally lower the recrystallization temperature of W,and it is believed that this effect is related to anenhanced diffusivity of Ni and Pd in the grainboundaries of polycrystalline W.

References: 104,105

B12: Instruments and Methods, Surface ScienceOur atom probe instrument is being continuouslyimproved. A new high voltage pulser has beenconstructed, methods for correction of pile-up effectin the ion detector has been developed and installed,and the energy dependence of the ion detector hasbeed determined and compensated for. In a paper allknown factors affecting the accuracy of quantitativeatom probeanalysis were treated. The effect of a highelectric field on the chemisorption of hydrogen wasstudied, with the aim of finding operating conditionsto minimise hydrogen adsorption during atom probeanalysis. The formation of molecular ions duringfield evaporation is being studied in collaborationwith theoretical physicists at Dalhousie Universityin Halifax, Canada.

References: 63-67

Publications

Ph.D. DissertationsJan Skogsmo, "Microstructurc of C VD Coaled CementedCarbides", May 26 1989

Göran Wahlberg, "The Role of Nitrogen in Duplex Stain-less Steels", June 9 1989

Jiyong Yao, "Transmission Electron Micrscopy of InxGal-xAs/GaAs Strained-Layer Structures", June 5 1990

Liu-Ying Wei, "Development of Microstruciurc in CastMagnesium Alloys", June 6 1990

Ulf Rolander, "Atom-Probe Microanalysis of Cermets",April 5 1991

Håkan Swan," Microstructurc and Properties of CeramicMatrix Composites", April 28 1992

Licentiate DissertationsThomas Hermansson, "Supcrplastic Deformation ofZirconia",May31 1989

Bocl Wadman, "Matrix composition in Zircaloy", Decem-ber 15 1989


MICROSCOPY AND MICROANALYS1S

Bertil Josefsson, "Microscopy and Microanalysis ofBainitic Weld Metal", December 11989

Maria Knutson-Wedel, "The Microstructure of HotIsostatically Pressed S13N4 Ceramics", May 14 1991

José Alarco, "Interfacial Microstructure of YBaqCu-jOi^High Tc Superconductors", January 18 1993

Diploma WorkJan Andersson, "Metoder för bestämning av tjocklek ochstruktur hos manganfosfatskikt", 1989

Pontus Jonsson, "Mikrostrukturen hos ZrOj-förstärktkiselnitrid framställd genom HIP", 1989

Mikael Kall, "Inverkan av metanol på tribosystemetkolvring-cylinderfoder", 1989

Jörgen Wulfsberg, "Mikrostrukturen hos martensitiska 12%kromstål', 1989

Per Lindahl,"Atomsondsanalys av bindefasen i TIC.TiN/Co", 1989

Per-Åke Eliasson, "Inverkan av värmebehandling ochkiselhalt pä mikrostrukturen hos Zircaloy-4", 1990

Lars Lundin, "Undersökning med atomsond och elektron-mikroskop av ett nyu martensitiskt 12%-kromstål", 1990

Mats Halvarsson, "Fretting of Nickel", 1990

Anne Bokedal och Herman Heijmans,"Gränszoncn mellangöt av dentallegeringar och solida metallelement", 1991

Magnus Persson, Titanbunden keramik", 1992

Lars Bengtsson, "Utskiljning av intermetalliska fasa i ettduplext rostfritt svetsgods", 1992

Gunnar Barrvik, "A Device for Cyclic Fatigue of CeramicMaterials Inside a Scanning Electron Microscope", 1992

Reports and articles1. "The microstructure of a Bi-Ca-Sr-Cu-0 high Tc

superconductor produced by rapid solidification", IngLiu, M. Knutson, Zhi-yi Liu, E. Olsson and G.L.Dunlop, Super cond ScTechnol. 1 (1989) 254-259.

2. "The microstructure of S13N4 and Z1O2 based ceramicmaterials and the effect of oxidation", Lena KL. Falk,STU final report nr 86-3348, March 1989.

3. "Microstructures of hot-pressed Si3N4/Zr02(+Y2O3)composites", L.K.L. Falk, T. Hermansson and K.Rundgren, J. Mater. Sci. Utters 8 (1989) 1032-1034.

4. "Microstructural development during processing of anSi3N4/ZrO2 material'', L.K.L. Falk and M. Holmström,in Euroccramics, edited by G. de With, R.A. TerpstraandR.Metselaar(Elsevier, 1989) pp. 1.373-1.377.

5. "Microstructures of S13N4 ceramics formed by HIP",E.M. Knutson, L.K.L. Falk and T. Ekström, in Euro-ceramics, edited by G. de With, R.A. Terpstra and R.Metselaar(Elsevier, 1989) pp. 1.416-1.420.

6. "Atom Probe Analysis of Zircaloy Needles", B.Wadman, H.-O. Andrén and L.K.L. Falk, J. Physique50(1989)C8-3O3-3O8.

7. "Pressureless Sintered Si3N4-ZrO2 Composites withAI2O3 and Y2O3 Additions", T. Ekström, L.K.L. Falkand E.M. Knutson-Wedel, J. Mater. Sci. Letters 9(1990)823.

8. "Microstructure and Oxidation Behaviour of S13N4/Z1O2 Ceramics", L.K.L. Falk, in proceedings of the11 th International Ris0 Conference "Structural Ceram-ics - Processing, Microstructure and Properties", editedby J J. Bentzen, J.B. Bilde-Sorensen, N. Christian, A.Horsewell and B. Ralph, (Ris0 National La'joratory,Roskilde, Denmark, 1990) pp. 277-282.

9. "Microstructure and Properties of S13N4 CeramicsFormed by HIP using Different Oxide Additives",E.M. Knutson-Wedel, L.K.L. Falk and T.Ekström, inproceedings of the 11 th International Ris0 Conference"Structural Ceramics - Processing, Microstructure andProperties", edited by J J. Bentzen, J.B. Bilde-Sorensen, N. Christian, A. Horscwcll and B. Ralph,(Ris0 National Laboratory, Roskilde, Denmark, 1990)pp. 377-382.

10. "Development of Microstructure in an Si3Composite Ceramic Material", in "Advanced StructuralInorganic Composites", L.K1. Falk, edited by P.Vincenzini (Elsevier, Amsterdam, the Netherlands,1991) pp. 169-178.

11. "Si3N4 Ceramics Formed by HIP using additions ofZrO2", E.M. Knutson-Wedel, L.K.L. Falk and T.Ekström, in "Ceramics Today - Tomorrow's Ceram-ics", edited by P. Vincenzini (Elsevier, Amsterdam,The Netherlands, 1991) pp. 1347-1356.

12. "Si3N4-ZrO2 Composites with Small AI2O3 and Y2O3Additions - Prepared by HD»", T. Ekström, L.K.L. Falkand E.M. Knutson-Wedel, J. Mater. Sci. 26 (1991) 4331.

13. "Elemental concentration profiles in an oxidised S13N4material", L.K.L. Falk and E.U. Engström, J. Am.Ceram. Soc. 74[9] (1991) 2286-2292.

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14. "Microstructure and short term oxidation of hot-pressed Si3N4/ZrO2 (+Y2O3) ceramics", L.K.L. Falkand K. Rundgren, J. Am. Ceram. Soc. 75[1] (1992)28-35.

15. "Si3N4 Ceramics formed by HIP using Different OxideAdditions - Relation between Microstructure andftnperties", E.M. Knutson-Wedel, L.K.L. Falk, H.Björklund and T. Ekström, J. Mater. Sci. 26 (1991)5575-5584

16. "Microstructure and Mechanical Properties of HotIsostatically Pressed Whisker Reinforced Si3N4

Ceramics", L.K.L. Falk, H. Björklund, J.E. Adlerbomand H.T. Larker, in "Proceedings of the 4th Interna-tional Symposium on Ceramic Materials & Compo-nents for Engines", edited by R. Carlsson, T. Johanssonand L. Kahlman (Elsevier, London, 1992) pp. 699-706.

17. "Effect of Intergranular Microstructure on Properties ofSijN4 Based Composite Ceramic Materials", E.M.Knutson-Wedel, L.K.L. Falk and T. Ekström, in"Proceedings of the 4th International Symposium onCeramic Materials & Components for Engines", editedby R. Carlsson, T. Johansson and L. Kahlman(Elsevier, London, 1992) pp. 244-251.

18. "Microstructure and Mechanical Properties of S13N4Based Ceramics", E.M. Knutson-Wedcl, L.K.L. Falkand T. Ekström, to be published in the proceedings ofthe European Ceramic Society Second Conference,Augsburg, Germany, September 11-14,1991.

19. "Microstructure and Mechanical Properties of Un-Doped and Low-Doped Whisker Reinforced S13N4Ceramics Formed by HIP', L.KL. Falk, H. Björklund,J.E. Adlerborn and H.T. Larker, to be published in theproceedings of the European Ceramic Society SecondConference, Augsburg, Germany, September 11-14,1991.

20. "Development of Microstructure in Hot IsostaticallyPressed AI2Q3 - SiC Whisker Composites", H.Björklund, LKL. Falk, L. Björk and H.T. Larker, tobe published in the proceedings of the EuropeanCeramic Society Second Conference, Augsburg,Germany, September 11-14,1991.

21. "Characterization of SijN4 Ceramics Formed withDifferent Oxide Additives", E.M. Knutson-Wcdel,L.K.L. Falk and T. Ekström, J. Hard Materials 3 [3-4](1992)435^45.

22. "Hislological and Chemo-Morphological Studies ofDeciduous Enamel in Amelogenesis Imperfecta", B.Bäckman, T. Lundgren, E.U. Engström, L.KL. Falk,J.M. Chabala, R. Levi-Setti and J.G. Norén, acceptedfor publication in Scand. J. Dent. Res.

23. "Zirconia Doped Silicon Nitride Ceramics", T.Ekström, L.K.L. Falk and E.M. Knutson-Wcdel. in"Ceramics, adding the value: AUSTCERAM 92",edited by M J. Bannister (CSIRO Publications,Melbourne, 1992) pp. 510-516.

24. "Microstructural Development of Si3N4 CeramicsFormed with Additions of ZrC^", L.K.L. Falk, to bepublished in Materials Forum.

25. "Intergranular Microstructure and Oxidation Behaviourof Si3N4 Ceramics Formed with Y2O3, AI2O3 andZ1O2", L.K.L. Falk, E.U. Engström and K. Rundgren,to be published in the proceedings of the MRS sympo-sium "Silicon Nitride Ceramics - Scientific andTechnological Advances", Boston, November 30 -December 4,1992.

26. "Grain Morphology and Intcrgranular Structure ofS13N4 Based Ceramics Formed by HIP", H. Björklund,L.K.L. Falk, J. Wasén, J.E. Adlcrbom and H.T. Larker,to be published in the proceedings of the MRS sympo-sium "Silicon Nitride Ceramics - Scientific andTechnological Advances", Boston, November 30 -December 4,1992.

27. "The rate controlling processes in the oxidation ofHIPcd Si3N4 with and without sintering aids", J. Chen,J. Sjöberg, C. O'Meara and L. Pcjryd, J. Eur. Ceram.Soc., 7,319-327, (1991).

28. "Corrosion behaviour of HIPed Si3N4 and a SiC/SiCComposite in Simulated Combustion Environments",J. Chen, J. Sjöberg, C. O'Meara and L. Pejryd, Proc. ofthe 4th Int. Symposium on Ceramic Materials andComponents for Engines, Gothcnburgh 1991, in press.

29. "The changes in the oxide scale formed on corodingnon-oxide ceramics", J. Chen, J. Sjöberg, C. O'Mearaand L. Pejryd, Proc. of the 2nd European CeramicSociety Conference (ECerS'91), Augsburg 1991, inpress.

30 "The effect of Yttria Additions on the Composition ofSialons prepared by Pressurclcss Sintering", J. Sjöberg,C. O'Meara and R. Pompe, accepted for publication inJ. Eur. Ceram. Soc.

31. "Thermal Deactivation of a Three-Way Catalyst:Changes of Structural and Performance Properties", B.Stenbom, G. Smedler, P.H. Nilsson, S. Lundgren, andG. Wirmark, SAE Technical Paper Series 900273,1990.

32. "Structural Deactivation of a Three-Way Catalyst", B.Stenbom, P. Lööf, and H. Norden, Micron and Micro-scopica Acta22,1991, pp. 177-178.



33. "Sintering of P1/AI2O3 Catalyst in Oj, CO, NO andCO+NO atmospheres", B. Stenbom, P. Lööf, and H.Norden, Micron and Microscopica Acta 23,1992, pp.221-222.

34. "Characterization ofaPt-Pd combustion catalyst on analumina washcoat, with and without prior hydrothcrmaltreatment of the washcoat", M. Skoglundh, L.O.Löwcndahl, P.G. Menon, B. Stenbom, JP. Jacobs, O.van Kcssel, and H.H. Brongcrsma, Catalysis Letter 13,1992, pp. 27-38.

35. "Development of interfacial microstnjcturc duringcooling of a ZnO varistor material", E. Olsson, R.Österlund and CL. Dunlop, J. Appl. Phys. 66 (1989)5072.

36. "Intcrfacial Microstructurc in YBa2Cu3O7^ High Tc

Superconductors", J.A. Alarco and G.L. Dunlop,Colloque dc Physique, supplement au n° 1, tome 51,(I990)Cl-959-964.

37 "Study of in situ laser deposited YBCO thin films", G.Brorsson, J.A. Alarco, Z.G. Ivanov, H. Olin, P.Å.Nilsson and T. Claeson, J. Less-Common Metals 164& 165,(1990)383-390.

38. "The interfacial microstructurc of SiC-whisker rein-forced Si3N4", A.H. Swan, E. Olsson, R. Lundberg andG.L. DunlopJ. Phys. 51 (199O)C1-1O43.

39. "Transport critical currents and microstructurc ofyttrium barium cuprate", D.A. Smith, D.R. Clarke,M.F. Chisholm, P.E. Balson and E. Olsson, Proceed-ings of the Xllth Congress for Electron Microscopy,San Fransisco Press, Inc., 32,1990.

40. "Hctcrocpitaxial growth of strained multilayer super-conducting thin films of Ndi.^Ceo.^CuOx/YBa2Cu3C>7.d", A. Gupta, R. Gross, E. Olsson, A.Scgmiiller, G. Koren and C.C. Tsuci, Phys. Rev. Leu.64(1990)3191.

41. "High critical current densities in strained multilayerthin films of NdiMCeonCiKVYB^C^Ov./, R.Gross, A. Gupta, E. Olsson, A. Segmiillcr, G. Korenand C.C. Tsuei, Appl. Phys. Lett 57 (1990) 203.

42. "High Quality YBCO Thin Films - Laser Deposition,Co-Evaporation, and Device Fabrication", J.A. Alarco,G. Brorsson, T. Clacson, M. Danerud, U. Engström,Z.G. Ivanov, P.Å. Nilsson, H. Olin and D. Winkler,Phys. Scrip. 44, (1991) 95-101.

43. "Effects of Composition and Processing on the Micro-structure and Properties of 1-2-3 Superconductors",J.A. Alarco, E. Olsson, H. Norden, H. Medelius andDJ. Rowcliffc, Micron and Microscopica Acla 22 (1/2), (1991) 105-106.

44. "YBCO thin films on yttria stabilised zirconia andLaAK>3: growth and properties", J.A. Alarco, G.Brorsson, T. Claeson, Z.G. Ivanov, M. Lofgrcn andP.Å. Nilsson, Physica C 185-189, (1991) 2017-2018.

45. "Properties of artificial grain boundary weak linksgrown on Y-Z1O2 bicrystals", Z.G. Ivanov, P.Å.Nilsson, D. Winklcr, I.A. Alarco, G. Brorsson, T.Claeson, E.A. Stepantsov and A. Ya. Trrfenchuk,Supcrcond. Sci. Technol. 4, (1991)439-441.

46 "Weak links and dc-SQUIDs on artificial nonsymmetricgrain boundaries in YBa2Cu3O7d", Z.G. Ivanov, P.Å.Nilsson, D. Winkler, J.A. Alarco, T. Claeson, E.A.Stepantsov and A.Ya. Tzalenchuk, Appl. Phys. Leu. 59(23), (1991) 3030-3032.

47. "Very thin YBaCuO films made by coevaporation", M.Danerud, P.Å. Nilsson and J.A. Alarco, E-MRS,Strasbourg, France, May 1991.

48. "YBaCuO thin films on Yttria-stabilised-Zirconia:growth and properties", J.A. Alarco, G. Brorsson, T.Gaeson, Z.G. Ivanov, M. Löfgrcn and P.Å. Nilsson, E-MRS, Strasbourg, France, May 1991.

49. "Properties of Artificial Grain Boundary Weak LinksGrown on Y-Z1O2 Bicrystals", Z.G. Ivanov, P.Å.Nilsson, D. Winkler, J.A. Alarco, G. Brorsson, T.Clacson, E.A. Stcpansov and A.Ya. Tzalenchuk,presented at the Third International SuperconductingElectronic Conference (ISEC 91), Glasgow, Scotland,June 25-27,1991.

50.

51.

"Observation of a vortex glass phase in polycystallineYBa2Cu3O7.d in a magnetic field", T.K. Worthington,E. Olsson, CS. Nichols, T.M. Shaw and D.R. Clarke,Phys. Rev. B 43 (1991) 10538.

"Crack formation in epitaxial [110] thin films ofYBa2Cu3O7.d and PrBajCuiOj^ on [110] SrTiOasubstrates", E. Olsson, A. Gupta, M.D. Thoulcss, A.Segmuller and D.R. Clarke, Appl. Phys. Lett. 58(1991) 1682.

52 "Elcctropolishing of polycryslallincmeet the need for sharp needle geometry", Q.-H. Huand J.A. Alarco, Surf. Sci. 266, (1992) 538-544.

53. "Effects of substrate temperature on the microstructurcof YBa2Cu3O7-d films grown on (001) Y-Z1O2substrates", J.A. Alarco, G. Brorsson, Z.G. Ivanov,P.Å. Nilsson, E. Olsson and M. Löfgren, Appl. Phys.Lett. 61 (6), (1992) 723-725.

54 "Growth and properties of a multilayer system basedon YBajCuj&jj and amorphous Y-ZrOf1, Yu. Boikov,Z.G. Ivanov, E. Olsson, J.A. Alarco, G. Brorsson andT. Clacson, J. Appl. Phys. 72 (1), (1992) 199-202.

236 THE CENTRE FOR


55. "Artificial grain boundary Josephson junctions -properties and applications", Z.G. Ivanov, J.A. Alaico,T. Claeson, RÅ. Nilsson, E. Olsson, HK. Olsson, E AStcpantsov, A. Ya. Tzalenchuk and D. Winkkr, BeijingInternational Conference on High Tc Superconductivity(BHTSC92). May 25-29.1992 Beijing. China.

56. "Cracking of brittle films on elastic substrates", M.D.Thoulcss, E. Olsson and A. Gupta, Acta metall. Mater.40(1992)1287.

57. "Laser deposited PrGaO3 films on SrTK>j substratesand in YBa2Cu3O7/PrGaO3/YBa2Cu3O7 trilayers", G.Brorsson, P.Å. Nilsson, E. Oisson, SZ. Wang, T.Clacson, and M. Lofgrcn Appl. Phys. Lett. 61 (1992)486.

58. "YBaCuO Josephson weak links based on shallow ionbeam etched steps in MgO Superconductivity'', J.Ramos, Z.G. Iva..ov, E. Olsson, and T. Claeson,(BHTSC92), May 25-29,1992 Beijing, China.

59. "Crossovers and vias in YBazCiÔr/PrGaOs/YBa2Cu3O7 trilayers", P.Å. Nilsson, G. Brorsson, E.Olsson, Z.G. Ivanov, and T. Claeson, 1992, Appliedsuperconductivity conference, Chicago, USA.

60. "Imcrfacial interactions between high Tc YBIQCUJ(>J.Xthin films and substrates", E. Olsson and S.L. Shinde, achapter in Interfaces in Superconducting Systems,edited by S.L. Shinde and D. Rudman, SpringerVerlag, New York, 1992.

61. "Microstructure of an artificial grain boundary weaklink in an YBat^CujOj^ thin film grown on a(100X110), [001] tilt Y-Z1O2 bicrystal", J. Alarco, E.Olsson, Z.G. Ivanov, P.Å. Nilsson, D. Winklcr, E.A.Stepanlsov, and A. Ya Tzalenchuk, accepted forpublication in Ultramiscroscopy. (N 9001191/9100293).

62. "YBaûaO^dGaOj/YBaÔr trilayers bymodified off-axis sputtering", SZ. Wang, E. Olsson,J A Alarco, Z.G. Ivanov, D. Winklcr, V. Langer, andP. Bcrastegui, submitted to J. Appl. Phys. (N 9001191/9100293).

63. "Statistical correction for pile-up in the atom-probedetector system", U Rolander and HO Andrén, J Phys(Orsay) 50,1989, pp. C8-529-534.

64. "Design of an atom-probe high voltage pulser", URolandcr and H-0 Andrén, Surf. Sci. 241,1991 pp.390-395.

65. "Quantitative atom-probe microanalysis", U Rolanderand H-O Andrén, submitted to Microscopy Microana-lysis Microstructurcs.

66. "Field dependence of hydrogen adsorption", H-0Andrén and U Rolander, Surf. Sci. 266.1992 pp. 76-80.

67. "On the performance of a microchannel plate detectorused for atom-probe analysis". L Lundin and URolander, Appl. Surf. Sci., in press

68. "Interaction between nitrogen and substiuitionalelements in the austenttic phase of duplex austeniuc-ferritic stainless steels", G Wahlberg, U Rolander andH-0 Andrén, in "High nitrogen steels, HNS 88", Book453, (The Institute of Metals, London, 1989) pp. 163-168

69. The kinetics of intermciallic phase formation induplex stainless weld metals and their influence onmechanical properties", L Karlsson, S Pak, LBengtsson and U Rolander, in "Appl. Stainless Steel92", in print

70. "Precipitation hardening of a new duplex stainlesssteel", M Liljas, P Stenvall, J Pleva and K Stiller, in"Appl. Stainless Steel '92", in print

71. "The role of alloy composition in the precipitationbehaviour of high speed steels", Wang Rong, H-OAndrén, H Wiscll and G L Dunlop, Acta Metall. Mater.40,1992 pp. 1727-1738

72. "Precipitation of secondary carbides during temperingof high speed steels", H-0 Andrén, in "Proc. 1st IntConf.High Speed Steels" edited by G Hack! and BHribemik, (Montanuniversitat Lcoben, Lcobcn, 1990)pp. 392-399

73. "Carbide precipitation in chromium steels", H-0Andrén, S Karagöz, Cai Guangjun, L Lundin and HFischmeister, Surf. Sci. 246,1991 pp. 246-251

74. "Microstructural changes during overtempering of highspeed steels", S Karagöz, H F Fischmeister, H-OAndrén and Cai Guang-jun, Metall. Trans. 23A, 1992pp.1631-1640

75. "A TEM investigation of a new creep resistant 12%chromium steel", L Lundin and H-O Andrén, Micronand Microscopica Acla 22,1991 pp.159-160

76. "Atom probe investigation of a creep resistant 12%chromium steel", L Lundin and H-O Andrén, Surf. Sci.266,1992 pp. 397-401

77. "Secondary hardening in high speed steels", S Karagözand H-O Andrén, Z Metallkunde 83,1992 pp. 386-392



78. "Atom-probe analysis applied to TiC-Ni basedcemented carbides", U Rolander and HO Andrén, in"Proc. 12th Int Plansee Seminar, edited by H Bildsteinand H M Ortner (Meiallwerk Plansee GmbH, Reutte/Tirol, 1989) Vol. 2 pp. 379-388

79. "Evaluation of atom-probe spectra from titaniumcarbonitride", U Rolander and HO Andrén, J Phys(Orsay) 50,1990 pp. C8-371-376

80. "Atom-probe analysis of a commercial cermet", PLindahl, U Rolander and H-0 Andrén, Surf. Sci. 246,1991 pp. 319-322

81. "Atom-probe microanalysis of TiC-TiN-Mo2C-Ni/Cocermets", U Rolander, C Chatfield and H-O Andrén,submitted to Acta Metall. Maler.

82. "High resolution microanalysis of cermets", P Lindahl,U Rolander and H-O Andrén, J. Hard Mater. 3,1992pp. 59-267

83. "Combined field ion microscopy and transmissionelectron microscopy of heavy ion damage in tungsten",K SUUer, Rad. Eff. Defects Sol. 115,1990 pp. 205-215

84. "Direct measurement of matrix composition inZircaloy-4", B Wadman and H-O Andrén, in "8th Int.Symp. Zirconium Nucl. Ind.", (ASTM STP1023,Philadelphia, 1989) pp. 423-434

85. "Atom probe analysis of thin oxide layers on Zircaloyneedles", B Wadman, H-O Andrén and L K L Falk, JPhys (Orsay) 50,1989 pp. C8-303-308

86. "Microstructural influence on uniform corrosion ofZircaloy nuclear fuel claddings", B Wadman, H-OAndrén, A-L Lundström, P Rudling and H Pettersson,accepted for publication in J Nucl. Mater.

87. "Microanalysis of the matrix and the oxide-metalinterface of uniformly corroded Zircaloy", B Wadmanand H-O Andrén, in "Zirconium in the NuclearIndustry: Ninth Int Symposium", edited by C MEucken and A M Garde (ASTM STP 1132, Philadel-phia, 1991) pp. 461-475.

88. "Microstnicture and themodynanmic behaviour of achromium molybdenum submerged arc weld metal inthe as welded state", B Josefsson and H-O Andrén,in'Recent Trends in Welding Science and Technology",edited by S A David and J M Vilek (ASM Interna-tional, Metals Park, OH, USA, 1990) pp. 243-247

89. "An APFIM study of the bainitic transformation in2.25Cr-lMo weld metal", B Josefsson and H-OAndrén, Mater. Sci. Technol. 7,1991 pp. 849-851

90 "Microstructure investigation of 12% Cr steel weldmetal", Cai G-J and H-O Andrén, Micron and Micro-scopica Acta 22,1991 pp. 127-128

91. "Microstructure and mechanical properties of 12% Crweld metal", Cai Guangjun, H-O Andrén and L-ESvensson, in "Proc. 3rd International Conference onTrends in Welding Research" (ASM, Metals Park,OH) accepted for publication

92. "Analytical TEM investigation of precipitation in a 5%Cr weld metal during tempering", Cai Guangjun, H-OAndrén and L-E Svensson, in manuscript

93. "Gold-germanium contacts on gallium arsenide", AKvist, Hu Q and H-O Andrén, J. Phys (Orsay) 50,1990pp.C8^65-470

94. "Atom probe analysis of the silver/gallium arsenidecontact", Hu Qiuhong, A Kvist and H-O Andrén, Surf.Sci. 246,1991 pp. 195-200

95. "Atom probe analysis of Au/GaAs and Ag/GaAsinterfaces", Hu Quihong, A Kvist and H-O Andrén,in"Microscopy of Semiconducting Materials", editedby A G Cullis and N J Long (Institute of Physics,Bristol, 1991) InsL Phys. Conf. Scr. Nr. 117, pp. 91-%

96 "TEM and atom probe analysis of melal/GaAs inter-face", Q-H Hu, A Kvist and H-O Andrén, Micron andMicroscopica Acta 22,1991 pp. 143-144

97. "High resolution microanalysis of AuGc contact on n-GaAs", A Kvist, Hu Qiuhong and H-O Andrén,submitted for publication

98. "Grain boundary chemistry in nickel base Alloy 600",K SUIler, J. Phys (Orsay) 50,1989 pp. C8-329-334

99. "InvesUgaUons of grain boundary microchemistry innickel base superalloys", K Stiller. Surf. Sci. 246,1991pp. 225-230

100. "Intergranular precipitation in Ni-Cr-Fe alloys", KSUller, Surf. Sci. 266,1992 pp. 402-408

101. "Grain boundary microstructure, chemistry andIGSCC in Alloy 600 and Alloy 690", K Norring, KSUller, J-0 Nilsson, in"5th Int. Symp. EnvironmentalDegradation of Materials in Nuclear Power Systems",(Amer. Nucl. Soc., La Grange Park, 1992) pp. 482-487

102. "Electropolishing of polycrystallineto meet the need for sharp needle geometry", HuQiuhong and J A Alarco, Surf. Sci. 266,1992 pp. 538-544

238 THE CENTRE FOR

MICROSCOPY AND M1CROANALYSIS

103. "Towards quantitative analysis of Y I ^ C ^ O ^high-Tc superconductor by AP-FIM", Hu Qiuhong, KSutler and H-0 Andrén, Appl. Surf. Set., in print

104. "The enhanced concentration of Ni at structuraldisloctions in a grain boundary in W" Lai Zonghe andH Norden, J. Phys. (Orsay), 49,1988, C6-341-345

105. "Nickel activated recrystallization of doped tungstenwire", Lai Zonghe and H Norden, InsL Phys. Conf. Ser.No. 93,1988, Vol. 2 p. 479-480

106. "Characterization of a-Al2O3 and K-AI2O3 and ot-ic Multioxide Coatings on Cemented Carbides", S,Vuironen and J. Skogsmo, Thin Solid Films, 193/194,1990,536-546

107. "Space Group Determination and Structure Modelfor K-AI2Q3 by Convergent -Beam Electron Diffraction(CBED)", Ping Liu and Jan Skogsmo, Acta CrysL,B47,1991,425-433

108. "The formation of ri-Phase in Cemented CarbidesDuring Chemical Vapour Deposition", J. Skogsmoand H. Norden, Refr. Met. & Hard Mater.,11,1992,49-61



Mechanics

Research SummaryThe determination of expected life or residual life ina material or product is essential for the total reliabi-lity and economy. The research activities of theMechanical Laboratory of SP are focused on thedevelopment and verification of methods for pre-dicting service life out of performed mechanicaltests, including improvements of the validity of suchtests.

Prediction of residual service life is essential formaintenance considerations and for several applica-tions where a prolonged use has become important.This also includes diagnostic methods to be used inservice as well as strength in aggressive environ-ments.

In particular, fatigue testing under spectrum load-ing or under the influence of an aggressive environ-ment is a crucial part of the performance and lifeassessment of a structure.

The research activities includes a.o. thefollowing:• development of mathematical methods for the

creation of spectra and for the evaluation offatigue data,

• development of mathematical models for lifeprediction,

• treating low cycle fatigue in certain applica-tions theoretically and experimentally,

• studying models for crack propagation andimplementing them into test methods,

• evaluating different methods for the determina-tion of residual stresses,

• determining mechanical properties underenvironmental influence.

Tribology is a related field of interest, since frictionand wear also have immediate importance for theperformance, reliability and economy of a compo-nent. The research in this field concerns boundarylayer lubrication, friction induced vibrations, andsliding contact under high pressure.

Within the laboratory also research in transporta-tion safety, product safety, quality assurance tech-niques and dynamic systems is performed. Thesesectors are not reported below.

AddressGibraltargatan 35Mail: Box 240 36S-400 22 Göteborg, SwedenPhone+46 31 2008 70Fax 446 31 161295

Research StaffGunnar Bergström

Lars O.EkerforsRMagnus HolmgrenJonas KarlssonGunnar KjellEva LarssonPer Lidström

Ulf OlofssonThomas SvenssonHåkan O.Torstensson

M.Sc,Head of Gothenburg branchDr.Eng.Sc.M.Sc.M.Sc.M.Sc.B.Sc.Dr.Eng.Sc. Head of SolidMechanics GroupM.Sc.M.Sc.Dr.Eng.Sc., Mgr.,Dept.of Material & Mech.

Major Instrumentation• Servohydraulic testing machines• Crash test facility• Uniaxial and biaxial servohydraulic vibration test

rigs• Various equipment for materials and technolo-

gical tests• Equipment for drop and impact testing• Scanning electron microscope• Electrodynamic fatigue testing machines• Climatic chambers• Friction and wear testing equipment

240 THE CENTRE FOR

SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - MECHANICS

Financial SupportMinistry of IndustryNordtestNordic Industry FundSwedish Rescue Serices BoardNUTEKFoundation for Heating Technology Research

Major Fields of ResearchA: Methods for service life predictionParticipants: Th. Svensson, P. Lidström, M.Holm-gren, E.Larsson, U.Olofsson, G.Bergström,J.Karlsson, G.KjellCollaborators: Dept of Mathematical Statistics atChalmers University of Technology/Univ. ofGöteborg, Dept. of Construction Technology,ChalmersUniv.,of Technology, Det norske Veritas,Oslo, ABB Corporate Research, VästeråsB: TribologyParticipants: L.Ekerfors, U.OlofssonCollaborators: FFV Materials Technology, AlfaLaval

Research ProjectsA: Methods for service life prediction

A l : Fatigue at varying amplifiesFatigue in material is the result of a large number ofrepeated loadings. The phenomenon has been thor-oughly investigated for loads with constant ampli-tudes, both theoretically and experimentally. Whenthe magnitudes of the loads vary, there is a problemof transferring knowledge and test results from theconstant amplitude case. Furthermore new fatiguemechanisms appear under spectrum loading. Theseproblems are treated in this project:

1. Developments of methods for life prediction atvariable amplitudes. These methods are based on anew simple fatigue mo^e!, discovered at ChalmersUniversity of Technology, utilizing level crossingsrather than cycle count. The aim is to find methodssimple enough to be readily applicable, but whichare possible to refine by incorpoprating e.g. know-ledge from fracture mechanics.

2. Developmentof methods to generate stochasticprocesses for fatigue testing. In order to test differentfatigue models and to study the fatigue phenomenonin detail, load sequences of a particular characterarerequired. It seems that the theory for stochasticprocesses is a useful tool to create load sequenceswith the desired properties.

100

80

60

Randomprocess,irregularityfactor = 0.5

stre

ss

40

20

0

-20

-40

-60

-8050 100 150

time (s)200 250



3. Verification by testing of theoretical modelsfor fatigue at variable amplitudes. Since fatiguetesting is time-consuming and costly it isdesirable toreduce the number of tests and still have statisticallyvalid results One part of the project is thereforefocused on the adaption of statistical methods for theanalysis of test results.

A2: Crack propagation models and da/dNmeasurements

The project aims at refining the da/dN techniques forconstant amplitude and spectrum loads. Models forcrack propagation have been studied. An error anal-ysis of the craCK length as a function of the compli-ance has been performed and software has beendeveloped to integrate Paris'equation. Implementa-tion of the techniques in corrosive environments anddetermination of threshold values are being planned.

A3: Fatigue in vehicles1. Nonpressurized tanks for tank vehicles have

occasionally been damaged in long distance trans-port, because the fatigue risk by, say, repeated im-pact stresses has not been accounted for in the designrules.

Measurements have been made on a tank vehiclein traffic. The results are being analyzed with twomethods: maximax response spectrum for singulardynamic overloads, and fatigue damage responsespectrum for repeated stresses.

2. Fatigue testing of railcar bogies has beenperformed with new methods. Load cycles with aprescribed level crossing distribution and irregular-ity factor have been generated and iterated via afeedback loop until cracks were detected. The projecthas involved software development to optimize boththe data storage format and the calculation algo-rithms.

3. A round robin exercize with 12 Europeanparticipants aimed at optimizing methods for datareduction and analysis for measured transport vibra-tions. The SP approach is founded on fatigue damageresponse spectrum analysis, which gives a basis fordeveloping fatigue test methods.

4. Glass-fibre reinforced plastics have attractednew interest as a material for transport tanks forcorrosives, due to its good compatibility, impact-absorbing ability and strength. The project aims atinvestigating the material properties with regard to

strength, durability, environmental resistance andfire behaviour. The suitability for hazardous materi-als transportation will then be evaluated.

A4: Environmentally assisted fatigue

The corrosion fatigue properties of four types ofstainless steel have been investigated. Two differentenvironments were used: ambient temperature airand 3% sodium chloride at +80°C. For the materialstested no corrosion contribution to the lowering ofthe fatigue limit could be identified. Surface defectsfrom the processing and the increased temperaturewere the significant causes.

A5: CFCJree Insulation for culvertsThe project investigates the material properties ofCFC-free insulation. The axial shear strength hasbeen determined by a recently developed methodand the creep properties are being examined. Resultsobtained show that existing fears for the insufficientthermomechanicalpropertiesof these materialshavebeen exaggerated. It will however be necessary todistinguish pressure induced deformation of theclosed cells from the temperature dependent creepdeformation.

ftnfular displacement P)

Coefficient of friction versus angular displacement.

242 THE CENTRE FOR


B:Tribok>gy

Bl: Friction at high contact pressuresA method has been developed for the determinationof the friction coefficient at high contact pressures(up to 300 MPa) and very low velocities, of the orderof nm/s. A servohydraulic torsion-tension testingmachine was adapted for the measurements.

The method was used for analyzing steel onconcrete, and to evaluate the performance of lubri-cants in steel against steel movement.

Lubricant no 1

B2: Friction Induced vibrationsStudies on the nature of interaction between slidingsurfaces have been made and recently applied to theproblem of friction-induced noise. It was concludedthat the friction induces vibrations between nut andscrew in a screw-nut transmission, which in succes-sion excite transverse vibrations in the screw.

Lubricant no 2

Lubricant no 3 Lubricant no 4

Response surfaces for moo.



ReferencesAndersson, Th., M.Holmgren and UJohansson, Glass fibre

reinforced plastics as a material in tanks for thetransport of dangerous goods, SP1992 (in Swedish)

Bergström, G., Comprcssive creep of polystyrene cellularplastics, SP 1989

Ekerfors, L. and U.Olofsson, Friction-induced noise inscrew-nut transmissions, WEAR, aug 1991.

Holmgren, M. and E.Larsson, Corrosion fatigue in duplexstainless steel, SP 1992 (in Swedish)

Jarfclt, U., G.Bergström and J.Karlsson, Load-beringcapability of CFC-rrce culvert insulation at servicetemperature, VärmcForsk, 1992 (in Swedish)

Lidström, P., Crack propagation and da/dN testing, SP1992 (in Swedish)

Olofsson, U. and M.Holmgren, Utilizing a servohydraulictorsion-tension machine to measure the frictionbetween steel and concrete at low sliding speeds, SP1992 (in Swedish)

Olofsson, U., Friction characteristics of a ferritic-austeniticstainless steel during lubricated reciprocating motion,SP1992

Olofsson, U., Stresses in tank vehicles, SP 1991 (inSwedish)

Olofsson, U. and Th.Svensson, Shock response spectra andfatigue damage response spectra for a tank vehicle, SP1991

Richards, D., Round-Robin Exercize on TransportationStresses,

Svensson, Th. and M.Holmgren: Numerical and Experi-mental Verification of a New Model for Fatigue Life,SP 1992, to be published in Fatigue and Fracture.

244 THE CENTRE FOR

Building materialsBuilding materials 246Building technology - Swedish National



Building Materials

Research SummaryThe division of Building Materials works mainlywith cement and wooden based building materialsand surface coatings on such materials. One majorpart is a material science approach to flow propertiesfor liquid, gas and ion transport in porous materials.Another major part is research on durability andservice life, i.e. the behaviour of materials in long-time use in various environments. The expectedservice-lives are from some decades to more than100 years.

Cement based materials age continuously. Thetime development of the structure, mainly themicropore structure, is studied from mixing to com-pleted haideninganditsrelationshipto the propertiesand behaviour regarding reaction and flow proper-ties is a key issue.

The work on durability and service-lifeisconcen-trated on parameters decisive for moisture condi-tions in general, emissions from surface coatings onconcrete floors, steel reinforcement corrosion inconcrete structures androot decay in exterior woodenstructures. Those parameters are the microclimate atthe surfacesof the materials, thedeterioration mecha-nisms and the reaction and flow processes involved.This knowledge is combined into models for pre-dicting the service life as a function of design,compositions of the materials and the environment.

AddressDepartment of Building MaterialsChalmers University of TechnologyS-412 96 Göteborg, SwedenPhone+46 31 7722299Fax +46 31 189705

StaffCAMIAV MflinhAit

L-O. NilssonR. TepfersL. BemtssonXu Aimin

Graduate StudentsE. AtlassiS. HjortK. NorlingJ. MöllerA. RadoceaMRodheK. ThaleniusTangLH. Wengholt

Technical StaffB. DellmingJ. AavikF.CalkoT. HammarbergB.HedbergA. JohnssonI. Limani

SecretaryA. Palmdin

LibrarianI. Gustafson

professordocenttekn.lic.tekn. dr.

civ.ing.civ.ingciv.ing.civ.ing.tekn.lic.civ.ing.civ.ing.B.Sc.civ.ing.

civ.ing.civ.ing.ing.ing.ing.tekn.ing.

Major Instrumentation• Thermobalance (TGA): LECO MAC-500,1991

(for 19 samples simultaneously)

• X-ray diffractometer (XRD): Siemens D5000,1992. Contact: B Dellming

246 THE CENTRE FOR

BUILDING MATERIALS

Major Reids of ResearchA: Structure of Cement-Based Materials

participants: E. Atlassi, L-0 Nilsson, A.Radocea, Xu Aimin.collaborators: Swedish Cement & ConcreteResearch Institute, Stockholm

B: Durability of Concreteparticipants: L. Bemtsson, J. Möller, L-0Nilsson, Tang Luping, Xu Aimin.collaborators: Cementa AB, Swedish TestingInstitute, Borås, LMDC, INSA-UPS, Toulouse

C: Moisture in Building Materialsparticipants: B. Hedberg, S. Hjort, L-0 Nilsson,K. Norling, M. Rodhe, K. Thalenius.collaborators: Royal Institute of Technology,Stockholm

Pore water pressure

4

P1

?2

Atmospheric

pressure

Forces acting on the structure:

Gravitation Capillary forces

P1 = initial pore pressureP2 = hydrostatic pressuret1 = total time of bleedingt2 = time when water menisci

develop at the top surface

Research Projects

A: Structure of Cement-Based Materials

Al: A Study on the Mechanism of PlasticShrinkage of Cement-Based Materials

Fresh concrete undergoes a volumetric contractionduring the very few hours after placing. This contrac-tion is caused by the sedimentation of cement parti-cles and aggregates (bleeding) and by the develop-ment of capillary forces due to water menisci be-tween the outermost particles of the concrete mass(plastic shrinkage).

In order to study the mechanism of bleeding andplastic shrinkagcatestmethodfor continuous meas-uring of pore water pressure in fresh and youngcement paste was developed at our division. Themethod of testing is based on the idea that water,cement grains and aggregates are incompressibleand that any force acting on the solid particles mustgive rise to a change in the pore water pressure, seefigure.

The aim of the project was to describe the devel-opment of capillary pressure in fresh cement pasteand todevelopamodelthatdescribes the mechanismof plastic shrinkage. It was shown that the capillarypressure is a function of the geometry of the spacesbetween the outermost solid particles, the rate ofevaporation and the volume change of the sample.

Changes in pore water pressurein fresh cement paste.

The total relative deformation of a sample can beestimated by measuring the development of the porewater pressure and the rate of evaporation.

A2: Plastic Shrinkage Clacking of ConcreteThe factors which control the development of thecracks have widely been discussed over the last fourdecades, but no generally accepted theory that de-scribes the mechanism of cracking can be found inthe literature.

The aim of the project is firstly to study theinfluence of parameters such as type of cement,water-cementratio, superplasticizer and rate of evapo-ration on the geometry of the outermost pores of theconcrete mass and on the modulus of plastic shrink-age. Secondly, a model to describe the developmentof the cracks and a method for estimating the risk ofcracking will be developed.

Normal concrete with water-cement ratios in therange of 0.6-0.8, as well as high performance con-crete are the objects of investigation.

The project will be carried out in collaborationwithNCCVäst,PlatzerByggABandFärdigBetong,the work consisting of both field and laboratorystudies.


BUILDING MATERIALS

B: Durability of ConcreteBl: Carbonatkxi In ConcreteAs a structural material, concrete has two mainfunctions. The concrete supports thv internal andexternal loading on the construction and acts as aprotective cover for the reinforcement. The durabil-ity of the concrete is important for both these func-tions, and durability aspects are receiving increasedattention by researchers as well as other parties of theconstruction industry. The deterioration process inconcrete structures is generally caused by a numberof mechanisms, one of which is carbonation.

Carbonation of concrete may in general be de-fined as the combination of ongoing chemical reac-tions of carbon-dioxide (CO2) with hydrated andunhydrated cement paste on one hand, and thetransport of gases, ions and water within the poresystem on theother hand. The CC^in the atmospheremainly derives from natural growth of vegetationprocesses and from industrial processes that usefossil fuels. In densely populated urban areas ex-haust from cars contributes with the greatest part ofthe CO2 in the local atmosphere.

Carbonation affects some important properties ofthe paste, but best known, and probably the mostimportant effect is probably the change in alkalinityor decreased pH level in the pore system. Thedecrease in pH level (from 13.5 to 8.5) depassivatesthe concrete steel reinforcement, resulting in corro-sion. The consequence of reinforcement corrosion isthe spalling of the concrete cover, often leading toirreversible deterioration or mechanical failure ofthe construction.

The aim of the project is to study and map thecarbonation process as a combined system, ratherthan looking, either on the chemistry alone or thetransport processes alone. A more complete descrip-tion of the complex mechanism of the combinedtransport and chemical binding of carbon-dioxide inconcrete is of great value in order to evaluate andpredict the service live of a reinforced concretestructure. The fundamental tools, used in the re-search program are mathematical modelling andcomputer simulation of destructive as well as non-destructive processes in the concrete, both duringearly hydration and during deterioration.

Collection and evaluation of information on car-bonation, available from the literature, especiallywith respect to gas transport coefficients, the relation

to the progress of cement hydration and the develop-ment of the pore structure in the concrete duringhydration and carbonation is an essential part of theprogram. With laboratory studies on the degree ofcarbonation we try to answer the question: Howmuch of the cement will or can carbonate? Differentenvironmental conditions, cement types and con-crete mixes are tested. Project completion is esti-mated in 1995.

B2: Influence of Alkali on Carbonationof Concrete

Regarding steel reinforcing-bar corrosion in con-crete, the neutralization induced by carbonation hasarised much concern. It has been shown that car-bonation of cement/concrete is a multi-factor de-pendent phenomenon, which, despite intense re-search, still remains to be fully explained. Amongthe many factors, the effect of alkali on carbonationis of special importance.

In the presence of CO2, alkali salts, such as K2Oand Na2O in concrete, react to form alkali-carbon-ates which are highly soluble. The alkali-carbonatesreadily react with the cement hydration products.This reaction causes dissociation of cement hydratesand re-produces alkali salts which will react withCO2 again. In this way, alkali behaves as a catalystto the cement carbonation. This mechanism has beenknown to lead to the fatal deterioration of highalumina cement products, but largely ignored for thecarbonation of other types of concrete.

Alkali salt is present as a component in cement ormineral admixtures (such as fly ash). It can also beintroduced as an activator for the mineral admixturessuch as slag and fly ash, or due to the contact betweenconcrete and alkali baring media. Thus concretesinevitably contain some amount of alkali which maybe one factor enhancing the carbonation process.The objectives of this project are:1. The mechanism of concrete carbonation in thepresence of alkalies. The research will be focussedon the effect of different types of alkali salts and theircontents, e.g., alkali oxide, alkali sulphate, etc., oncarbonation reaction.2. Carbonation rate of different concretes, i.e., con-cretes made of different cements and/or with addi-tion of mineral admixtures, influenced by alkali. Theconcretes studied will be subjected to both labora-tory accelerated carbonation and natural carbona-tion environments. Special interest will be placed on

248 THE CENTRE FOR

BUILDING MATERIALS

the carbonation of the alumina-baring hydrationproducts. This, in addition to practical interests, mayelucidate the mechanism for the usually higher rateof carbonation in concretes incorporating Class F flyash (note that aluminate phase in this type of fly ashis one of the main pozzolanic active components).

B3: Chloride Transport In MaritimeConcrete Structures

Chloride transport in concrete plays an importantrole in the durability of a reinforced concrete struc-ture, especially when the structure is exposed inmaritime environment. The transport is, however, arather complicated process which involves diffu-sion, capillary suction and, sometimes, electro-phoresis, accompanied by chemical and physicalbinding. It is of great value to study the combinedmechanism of chloride transport in concrete in orderto evaluate and predict the service life of a reinforcedconcrete structure.

The aim of Sub-project 1 is to identify some of themost important parameters of the environment, af-fecting the rate of chloride transport into concrete.Environmental parameters studied in Sub-project 1include a) the chemical composition of "seawater",b) climatic changes such as the frequency of wet-drycycles in the "splash zone", temperature and relativehumidity. The features of the "splash zone" is ofprimary concern, since some mechanisms of trans-port (e.g. capillary suction, deposition of chloridedue to wet-dry cycles, temperature effects, etc.)other than pure diffusion may be of relative impor-tance.

ri*

0,00

*

N o \

0 10 » 10

Otpft HtM ttå Mfftft, M l

Chloride penetration profiles after half a year'simmersion in different solutions.

Concretes with the same mix designs are alsosubjected to field exposures at the Träslövslägeharbor in a parallel project for comparison.

B4: Properties of Aged Reinforced ConcreteMostly testing is carried out on young concrete andthus the testing results of aged concrete are notavailable. It makes it difficult to predict the servicelife of concrete structures. Environmental factorswhich include wetting and drying, temperature vari-ation, freezing and thawing, carbonation, chlorides,sulphur and nitrogen oxides etc, will influence theconcrete properties to a great extent, specifically itsstructure, capillarity and the hydration products ofthe cement paste.

In this project 6 years old weathered steel rein-forced concrete specimens should be analyzed usingphycical and chemical methods. Eight types of con-crete compositions including structural lightweightaggregate concretes will be tested. Four types ofsurface treatments has been given to each of theseconcretes. Rehabilitation of weathered concrete sur-faces with different methods and their subsequentinfluence on the important properties are to be evalu-ated. Realkalisation of carbonated concrete and chlo-ride extraction both by electrochemical methods arealso to be studied in laboratory conditions. Indica-tion has been found that these methods might havedeleterious effect on the concrete structure.

C: Moisture In Building Materials

Cl: Moisture in Painted Exterior Wood PanellingHouses should be designed and constructed in sucha way as to prevent future damage by moisture androt. Asa step towards reaching this goal, researchersat Chalmers University of Technology (CTH) andthe Royal Institute of Technology (KTH) are plan-ning to conduct a joint research project in respect ofmoisture in painted exterior wood panelling. Thestudy has two aims. The first is the development oftesting and evaluation methods to make it possible topredict, for different paint systems, the moisturebalance in painted exterior wood panelling, herebyavoiding future damage caused by rot. The second isto provide balanced recommendations regarding thedesign and coating of panelling made of differenttypes of wood, with a view to reducing the mainte-nance of exterior wood panelling in the future.


BUILDING MATERIALS

Test-panel

Balance

Water-spray

Top board seen fromthe reverse side

Measuring pointfor moisture ratio

Schematic drawing of a test setup for monitoring moisture conditions in coatedpanels. The moisture ratio in the wood and the weight of the panel are measured.

250 THE CENTRE FOR

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The project will involve basic research, whereprimarily the mechanisms governing moisteningand drying up will be studied in order to develop arelevant evaluation method for determining themoisture balance in painted wood constructions, aswell as more applied research, which will result inguidelines for the choice of coating, materials andbuilding techniques. The study will focus on coatingwith water-borne paint systems. Besides pine, thepanelling material studied will include differenttypes of wood-based hard-board panels. The part ofthe study focusing on building techniques will dealwith joints, nail holes and overlapping surfaces.

The CTH-side of the project will be led by StefanHjort, MSc, Building Materials, and the KTH-sideby Birgitta Hässler, PhD, Building Engineering.Stefan Hjort will be responsible for the theoreticalcalculations, laboratory measurements and meas-urements carried out at CTH's test-house on theSwedish west coast. Birgitta Hässler will be respon-sible for the build-up of knowledge in terms ofmaterials and paints, for the verification of theorieson moisture balance through computer tomographyas well as for electron microscopy with regard to thepenetration of penetrating oil and paint into the woodmaterials. The study will be evaluated and reportedin co-operation between the two divisions.

ReferencesS. Hjort (I989) "Rot Problems in External Wood Panels",

Publ P-89-4, Div. of Building materials, ChalmersUniversity of Technology (In Swedish).

S. Hjort (1991) "How to keep coated wood structuressufficiently dry to avoid damage caused by rot", IRGdocument 2376.

S. Hjort (1992) "Moisture transport in wood panel - aquestion of coating and building techniques, Publ P92:8, Div. of Building materials, Chalmers Universityof Technology (In Swedish).

C2: SeffOrying ConcreteA high moisture content in concrete is one reason fordamage to vinyl floorings. In the last few years manydamages to vinyl floorings on concrete slabs haveoccurred in Sweden, which can partly be explainedby poor adhesiveness, blisters and bubbles caused bysponification of glue and expansion of the vinyl.Also, the emission of chemical components in-creases when vinyl floorings are exposed to alkalinemoisture.

The concrete must dry out to an average moisturecontent corresponding to a critical level of relativehumidity (RH) in the material, before a vinyl floor-ing is laid. The RH should not exceed 85-90% formost vinyl floorings used in Sweden today. Theprocess of drying is very slow in concrete. Conse-quently, in thick slabs placed on top of an underlyingimpermeable material, such as a steel form work orcellular plastic insulation, the moisture transport isreduced to one direction and the drying time be-comes unreasonably long. For such structures it isfavourable to use a self-drying concrete.

Self-drying concrete has a low water-to-cementratio and a higher cement content than ordinaryconcrete. A large amount of the mixing water isbound chemically to cement and the amount ofexcess moisture left todry out is small. This concretedries out, even under sealed conditions, to an RHbelow the critical RH in about one month's time.

At the building site, however, the concrete may beexposed to very unfavourable drying conditions,such as additional water, high RH in surrounding airand low curing temperature. It is therefore necessaryto examine other properties than internal drying.These include the permeability of water and otherliquids, shrinkage due to high cement content, theprocess of hydration at low temperatures and lowRHs as well as workability.

References:K. Norling-Mjörnell,"ScIfdcsiccation in Concrete",

International Conference on Chcm. of Cement, India,1992. H. Wengholt-Johnsson, K. Norling-Mjörncll,"Fuktmätningar i betongbjälklag med kvarsittandcform, Stenkullen", 1992, (in Swedish).

K. Norling-Mjömell, "Ullorkning av platsgjutna T-bjälklag, fullskaleförsök och datorsimulering" (inSwedish), 1992.

ordinary concrete

85

80-

t-

Self-drying concrete

-The gain in time —admit an earlierstart to lay flooring

appr. 6 month

Relative humidity versus time forordinary and self-drying concrete.


BUILDING MATERIALS

Publications

Ph.D. DissertationsT. Kulli, "Alkali-Activated Slag Mortar - Mechanical

Strengths, shrinkage and structure", May 90Xu Aimin, "Structure of Hardened Cement-Fly Ash

Systems and Their Related Properties", Nov 92

Licentiate DissertationsXu Aimin, "The Structure and Some Physical Properties of

Cement Mortar with Fly Ash", Nov 90A. Radocea, "Pore Water Pressure Conditions in Young

Cement Paste - Method of Measurement, PreliminaryModels and Parameter Studies", May 91

T. Yokoyama, "A Field Study on Winter ConcretingMethods", Oct 92

Diploma WorkE-88:l97. Sjödin Eva, Taktäckning i Göteborg stads

bostadsaktiebolags fastighetsbestånd - Skador-problcm-åtgärder

E-88:298. Lorentzon Magnus, Tryckutmattning av höghållfast

betong

E-88:399. Wennberg Malin, Olsson Lydia, Metod för resistiv

flcrpunktsmätning av fuktförlopp i träpaneler

E-88:4100. Kadcfors Anna, Nedbrytning av natursten - inverkan

av luftförorening - en fältstudie

E-89:l101. Camncrt Peter, Svens Patrik, Fukt i träsyllar på

betonggolv med luftspaltbildandc fukuspärr

E-89:2102. Pettersson Mikael, Samuelsson Kristina, Metod för

fuktdimensioncring av uteluftsvcntilcrade kryprum

E-89:3103. Jansson Elisabeth, Kilenstam Ttwrcsc, Spikning av

träfasader

E-89:4104. Norling Kristina, Nilsson Andrea, Trähuspanclcr -

förr och nu

E-89:5105. Fritzell Esbjörn, Mankönen Timo, Tryckutmallning av

höghållfast betong

E-89:6106. Witzell Pär, Forsberg Lennart, Fuklvandring i fasader

med puts på mincralullsisolcring (Ej publicerad)

E-90:l107. Maria Palsclius, Egenskaper hos bruk med kalk <Vu

mald pimpsten som bindemedel - Laboratorieförsök

E-90:2108. Nils Ericsson, En undersökning av fukttillstånd i några

inneluftventilerade krypgrunder av lättbetong

E-9O:3109. Åsa Svensson, Thercse Samuelsson, Undersökning av

fuktproblem i Bagaregårdsskolan, Göteborg

110. Eva Hedberg, Kaisa Svennberg, Blir vit panelfuktigare än röd? - en studie av temperaturförhållandeoch fukttillstånd i lockpanel

E-91:2111. Giscla Carlén, Fuktmekanisk analys och fuktdimen-

sionering av fuktskyddet i småhus

E-91:3112. Eva Lundin, Ultorkning och uttorkningskostnadcr för

fukt i betongbjälklag

E-92:l113. Maria Änder, En studie av fönstcrskador, Olofshöjds

studenthem

E-92:2114. Thomas Dalmalm, Sediment wear on concrete hydro

constaictions

E-92:351S. Per Ks'lsson, Sprickfri kringgjuuiing - analys av en

metod för sprickfri kringgjutning av befintligabctongpelarc

E-92:4116. Jasmine Gustafsson, Hclana Patrikson, Fungerar våra

krypgrunder - en studie av fuktförhållandcn ochmögelförekomst i utclufls-ventilerade krypgrunder

Reports and artides1. Stefan Hjort, Jämförande fuklkvotsbcstämning oå

stavlimmad bänkskiva av rödbok Uppdragsgivare:Junkers, Kaj Knstoffcrscn (Göteborg, Mars 1988)

2. Juhan Aavik, Satish Chandra, Mats Rodhc, Testing ofpumice stone concrete block from Ethiopia andpuzzolanic test of pumice from Nicaragua (Assignmentfrom CBC Engineering, Kungälv, March 1988)

3. Mats Rodhc, Puz/olanic test on pumice from Ethiopia(Assignment from CBC Engineering, Kungälv, March1988)

252 THE CENTRE FOR

BUILDING MATERIALS

4. Mats Rodhe, Puzzolanic test on pumice from Nicaragua(Assignment from CBC Engineering, Kungälv, March1988)

5. Satish Chandra, Concrete-Polymer composites(RILEM TC-105 CP C, Göteborg, April 1988)

6. Saiish Chandra, Xu Aimin, A discussion on the paper"Assessment of simple methods of determining the freechloride ion concrete of cement paste" (Infört i Cement& Concrete Research, Vol 18, Nr. 4 1988)

7. Satish Chandra, Sate of the art in Scandinavian refrac-tory technology (Bidrag till Annual Meeting Abstractsof the American Ceramic Society, Cincinnati, Ohio,May 1988)

8. Satish Chandra, Xu Aimin, Influence of polymeraddition on the rate of carbonation of portland cementpaste (Infört i The International Journal of CementComposites and Lightweight Concrete, Vol 10, Nr. I1988)

9. Stefan Hjort, Lars-Olof Nilsson. En studie av klimat-påverkningar av målad träpanel drabbad av röLskador(Nordtcst-symposium, 1-2 Juni 1988)

10. Satish Chandra, Hydrochloric acid attack on cementmortar - An analytical study (Infört i Cement andConcrete Research, Vol 18, Nr. 2 1988)

11. Roman Malinowski, Betongens förhistoria (Artikel iNordisk betong, Oktober 1988)

12. Satish Chandra, Influence of pollution on mortar andconcrete deterioration (2nd NCB International seminar,Indien Januari 1988)

13. Lars-Olof Nilsson, Nya skador vid platta på markArtikel i Tidskriften Byggforskning

14. Leif Bemtsson, Satish Chandra, Ultrahöghållfastbetong. Tillverkningsprinciper (Göteborg, November1988Xska ingå i BFR:s Rapport serie, R8:1989)

15. Stefan Hjort, Färger för trä utomhus. Förberedandeinformation inför studie besök hos JOTUNA A/S,Sandefjord, Norge, 2 December 1988, (Göteborg,November 1988)

16. Lars-Olo' Nilsson, Fukt och mögelproblem vid betong-golv på mark - av brist på materialkunskaper(Göteborg, December 1988)

17. Saiish Chandra, Per Flodin, Interaction of polymerwith calcium hydroxide and tri calcium silicate

18. Leif Bemtsson, Polymermc ifierad cementbetong(Föredrag vid VTTs Bromaicrialdagar i Linköping 12-13 April 1989)

19. Stefan Hjort, Felaktiga färger kan göra hus sjuka(Artikel i Träinformation Nr. 7 Juni 1989)

20. Durability of concrete aspects of admixtures andindustrial by-products (2nd International seminar,CTH, 26-27 Juni 1989)(BFR Document, D9:1989)

21. Satish Chandra, Influence of pollution on mortar andconcrete (BFR Rappport nr. 830910-4) Göteborg 1990

22. Ralejs Tepfers, Conference of young scientists inIrkutsk (Reserapport 1990-05-10—15)

23. Stefan Hjort, Lars-Olof Nilsson, Rot problems andmoisture balance in painted external wood (Contributionto "Building Physics in the Nordic Countries"Trondheim, Norge Augusti 1990)

24. Leif Bemtsson, Satish Chandra, Tomas Kutti, Principlesand Factors Influencing High Strength ConcreteProduction (Artikel införd i "Concrete International",Nr. 12, December 1990)

25. Xu Amin, Satish Chandra, A Discussion of the Paper"Ice in Cement Paste as Analyzed in the Low-Tempe-rature Scanning Electron Microscope" (Infört i Cementand Concrete Research, Vol 20,1990)

26. Tang Luping, Interrelations Between Water, Gas andIon Penetrations of Concrete (Bidrag till "NordicConcrete Research" i Trondheim, 15-18 Augusti 1990)

27. Elisabeth Atlassi, High Strength Concrete - theInfluence of mix Proportions on some Mechanical andPhysical Properties (Bidrag till "Concrete for theNineties", Lcura, Australien 1990)

28. Satish Chandra, September - Oktober 1990, Reportfrom Travel to Japan and China (November 1990)

29. Xu Aimin, Satish Chandra, Juhan Aavik, Polymer inConcrete Proceedings of the 6th International Congress(Tongji University, Shanghai, China, September 24-271990)

30. Stefan Hjort, Juhan Aavik, Kristina Norling, Fukt-undersökning av trähus oå Eriksbergs varvsområde(Uppdragsgivar: Jacobsson & Widmark, Uddevalla1990-11-19)

31. Saiish Chandra, Report from International Symposiumon Concrete Polymer Composites (Bochum-Germany,March 12-14,1991)


BUILDING MATERIALS

32. Stefan Hjon, How to keep coated wood structuressufficiently dry to avoid damage caused by rot (Paperprepared for the 22nd annual conference, 20-24 May,Kyoto, Japan)

33. Leif Bcrntsson, Satish Chandra, Läuballast med höghållfasthet (BFR-anslag 890408-9 frän Statens råd förbyggnadsforskning till Färdig betong AB, Göteborg)

34. Trng Luping, Lars-Olof Nilsson, Rapid Determinationof the Chloride Diffusivity in Concrete by Applying anElectric Field (Bidrag till American Concrete Institute,Boston, MA, March 17-21 1991)

35. Lars-Olof Nilsson, Kristina Norling, Bedömning avintorkning hos Swedeck-ribbjälklag (Göteborg, Maj 1991)

36. Mats Rodhe, Tcletorn i Bergsjön (Uppdragsgivare:Consultadministration AB, Göteborg, Juni 1991)

37. Elisabeth Atlassi, The Influence of Silica Fume andSome other Parameters on the Compressive strength ofConcrete (Bidrag till "Blended Cements in Construction",Sheffield, September 1991)

38. Elisabeth Atlassi, Kristina Norling, Adrian Radocca,Fuktfri betong - en fråga om ratt material- kombination(Artikel införd i "Betong", Nr 3,1991)

39. Xu Aimin, Kristina Norling, Tång Luping, Jön Möller,Methods for structural study of Cement Paste and TheirApplication in Highpcrformancc Concrete (September1991)

40. Satish Chandra, Reserapport International Congress on"Polymer in Concrete" och besök på University ofChicago, September 1991

41. Elisabeth Atlassi, Influence of Cement Type on theDcsorption Isotherm of Morur Jnfört i "NordicConcrete Research", Nr. 10,1991)

42. Elisabeth Atlassi, Some Moisture Sorpu'on Propertiesof Silira Fume Mortar (Bidrag till "Fourth CANMET/ACI International Conference on Fly Ash, Silica Fume,Slag and Natural Pozzolans in Concrete", Istanbul 10-13 May 1992)

43. Lars-Olof Nilsson, Mincraliska material, grundläggan-de forskning, material och metodutveckling (Läges-rapport till BFR för perioden Juli 1989 - Februari 1991)

44. Satish Chandra, Xu Aimin, Influence of Presaiurauonand Frecze-Thaw Test Conditions on Length Changesof Portland Cement Mortar (Införs i "Cement andConcrete Research", Vol 22, Nr 4, May 1992)

45. Shondeep L. Särkar, Satish Chandra, Interdependenceof Microstructure on the Strength of Structural Light-weight -aggregate Concrete (Införs i "Cement &Concrete Compostes")

46. Tomas Kutti, Leif Bcrntsson, Satish Chandra, Shrink-age of Cements with high Content of Blast-FurnaceSlag (Bidrag till "Fourth CANMET/ACI InternationalConference on Fly Ash, Silica Fume, Slag and NeutralPozzolans in Concrete", Istanbul, 10 -13 May 1992)

47. Satish Chandra, Travell report to CANMET/ACIConferences on Concrete with Mineral Admixtures atIstanbul and Athens (Istanbul and Athens, 3 -13 May,1992)

48. Xu Aimin, The Shrinkage and Bulk Modulus ofCement-Fly Ash Mortar (Bidrag till "FourthCANMET/ACI International Conference on Fly Ash,Silica Fume, Slag and Neutral Poz/.olans in Concrete",Istanbul, 10-13 May 1992)

49. Adrian Radocca, A New Method for StudyingBlccnding of Cement Paste (Artikel i "Cement andConcrete Research", Vol 22, nr 5,1992)

50. Satish Chandra, Durability of Concrete with MineralAdmixtures Mixing (Ett kapitel till en bok om "Minc-raliska tillsatsmedel i betong", skall publiceras i Indien,ABI Books, New Dcti)

51. Stefan Hjort, Undvik rötskador genom att använda rättfärg (Bidrag Ull Gullfibers "fuktdag", Maj 1992)

52. Shondeep L. Särkar, Satish Chandra, Microstruciura!Investigation of Masonry Deterioration in an HistoricalChurch Tower, Gothenburg, Sweden (7th InternationalCongress on Deterioration and Conservation of Stone,Lisabon, Portugal 15-18 Juni 1992) (Proceedings,Volume 2)

53. Salish Chandra, Water Absorbing Polymer in CementMortar (Bidrag till "Congress on Polymers in Con-crete", September 1992)

54. Kristina Norling-Mjömell, Uttorkning av plastgjutnaT-bjälklag fullskaleförsök och datorsimulering(Göteborg, Oktober 1992)

55. Stefan Hjort, Rötskadade träfasader. Orsaker ochåtgärder. (Fuktinformation)

56. Kristina Norling-Mjömell, Fuktmätningar vid Arvikasjukhus Byggfuktfri betong

57. Elisabeth AUassi, Dcsorption isotherms of silica fumemortar (9th International Congress on the Chemistry ofCement, New Delhi, India, 23-28 November 1992)

254 THE CENTRE FOR

BUILDING MATERIALS

P-88:458. Lats-Olof Nilsson, Fukttransportegenskaper hos trä och

träbaserade skivor - en byggnadsfysikalisk inventeringoch analys av kunskaper och kunskapsbehov.(STU-ansIag86-O484P)

P-88:559. Lars-Olof Nilsson, Juhan Aavik, Utredning av fukt-

och mögelproblem, Torslanda. Undersökning av tiofastigheter i kv Trollrunan, Lönnrunan och Ö Lönnrunaa

P-88:660. Mats Rodhe, Fuktvandring i silovägg av betong.

(Uppdragsgivare: Hallands lantmän, okt 1988)

P-88:761. Lars-Olof Nilsson, Juhan Aavik, Undersökning av

flytspackelproblem i flcrbostadshus, BRF Mariestads-hus 10, Mariestad

P-89:l62. Tomas Kutti, Skador på ytputs i serporocksystcm.

(Uppdragsgivare: Emströrn & Co. AB, Mars 1989)

P-89:263. Tomas Kutti, Rötskador i träpanel. Etapp I: Husinvcn-

tcring.

P-89:464. Stefan Hjort, Rötskadade träfasader i en klimatiskt

utsatt miljö. En utredning av rötskador med speciellinriktning mot småhusområdet Torpet, Lysekil, Etapp H.

P-90:265. Tomas Kutti, Skador på ytputs i serporocksystcm -

Fortsättning. (Uppdragsgivare: Emström & Co, AB,Febru: i 1990)

P-9O:366. Bengt Dcllming, Fuktbalans i lockpanclvägg målad

med olika färgsystem - en laboratorieundersökning(Delrapport, intern för Alcro-Beckers AB)

P-90:467. G Ekman, T Yokoyama, T Kutti, Metoder att hålla

betongen varm vid gjutning vintertid

P-90:568. Lars-Olof Nilsson, Fukttransportegenskapcr hos furu,

gran och träbaserade skivor - Vcrifieriiig och komplet-terande bestämning (STU-anslag 86-04894P)Preliminär utgåva

P-90:669. Tomas Kutti, Alkali activated slag mortar- mechanical

strengths, shrinkage and structure (Doktorsavhandling)

P-90:770. Bengt Dcllming, Fuktbalans i lockpanelvägg målad

med olika färgsystem - en laboratorieförsök(Omarbetad version)

P-90:870. Ralejs Tepfers, Fatigue of concrete structures (Paper

presented at a Nordic seminar in Göteborg 1989)

P-90-.971. Xu Aimin, The Structure and some Physical Properties

of Cement Mortar with Fly Ash (Lic.uppsats)

P-90:1072. Tomas Kutti, Juhan Aavik, Rötskador i träpanel. Etapp

II: Husbesiktning

P-90:ll73. Satish Chandra, British Swedish Seminar on Concrete

Repairs (CTH, Göteborg, 10-11 December 1990)

P-91:274. Tang Luping, Tomas Kutti, Parkcringsdäck av betong.

Skadestatus och reparationsbehov. Reparationsmetoder.Etapp I: Inventering. Del 1: Repair methods forparking decks - a literature survey

P-91:375. Lars-Olof Nilsson, Parkeringsdäck av betong. Skadesta-

tus och reparationsbehov. Reparationsmetoder. Etapp I:Inventering. Del 2: Inventering av P-husbeståndct iGöteborg

P-91:476. Stefan Hjort, Kristina Norling, Fuktbalans i lockpanel-

vägg målad med fyra olika färgsystem - en fältmätning

P-91:577. Adrian Radocea, Porvattcntryckförhållanden i ung

cementpasta. Mätmetod, preliminära modeller ochparameterstudier (Lic.uppsats)

P-91:878. Juhan Aavik, "90-lalets golv"

P-91:979. Bengt Dcllming, Ilias Limani, Fuktbalans hos träpanel

målad enligt hydrolin-metodcn - Inverkan av baksides-bchandling

P-91:1080. Bengt Dcllming, Ilias Limani, Fuktbalans i

lockpanclvägg

81. Leif Bcmtsson, Lars-Olof Nilsson, Betongteknologi,Fukt i porösa Byggnadsmaterial. Kompendium iByggnadsmaterial för V3


BUILDING MATERIALS

P-91:1282. Xu Aimin, Vapour sorption theories, Seminaricuppgift

till doktorandkurs. 'Transportprocesser i byggnads-material"

P-92:l83. Xu Aimin, A mincralogical-microscopical study of

cement pastc/mortar incorporated with fly ash

P-92:284. Takashi Yokoyama, A field study on winter concreting

methods. Part I: Main report (Hobcrg site, Göteborg1988/89) (Lic.uppsats)


methods. Part II: Data report (Hobcrg site, Göteborg1988/89) (Lic.uppsats)


methods. Pan III: Two dimensional analysis (Hobcrgsite, Göteborg 1988/89) (Lic.uppsats)

P-92:587. Lars-Olof Nilsson, Tang Luping, Relationships

between flow coefficients for moisture, water, gasesand ions in concrete

P-92:688. Tang Luping, Lars-Olof Nilsson, Test methods for

transport of ions in concrete

P-92:789. Xu Aimin, Structure of hardened cement - fly ash

systems and their related properties (Doktorsavhandling)

P-92.-890. Stefan Hjon, Mätning av fuktbalans i mälad lockpancl

-jämförande provning mellan olika färgsystcm ocholika konstruktiva utföranden

P-92:991. Adrian Radocca, A study on the mechanism of plastic

shrinkage of cement-based materials

P-92:1092. Leif Bcmlsson, Lars-Olof Nilsson, 3etongteknologi,

Fukt i porösa byggnadsmaterial (Kompendium ibyggnadsmaterial för V3)

P-92:ll93. Leif Berntsson, Lars-Olof Nilsson, Exempelsamling i

byggnadsmaterial (Byggnadsmaterial för V3)


methods. Part I: Main Report, Part II: Dala Report, PartIII: Dimensional Analysis (Hobcrg site, Göteborg1988/89) (Lic.uppsats)

P-9?:1395. Lars-Olof Nilsson, A theoretical study on the effects of

nonlinear chloride binding on chloride diffusionmeasurements in concrete (Toulouse i Maj 1992)

P-92:1496. Lars-Olof Nilsson, The replica technique of Insa-

Toulouse - a powerful tool for studying the develop-ment of microcracks in high-performance concrete?(Toulouse i Juni 1992)

256 THE CENTRE FOR


Building Technology

Research summaryApplied and to some extent basic research is per-formed mainly in the field of wood and woodbasedmaterials, cement and concrete but also where ma-sonry, stone and other inorganic building materialsare concerned. An important goal of the research isto develop test methods. Performance testing andnon destructive testing techniques (NDT) are ofspecial interest. In order to calibrate the test methodsagainst "reality" and to develop new material mod-els, field exposure tests play an important role in ourresearch. Another speciality is microscopical studiesof materials by use of the so called thin sectiontechnique and by scanning electron microscopy.

NDT-techniques are developed for classifyingtimber (automatic stress grading). Equipment forthree different stress grading techniques are avail-able at the laboratory. In a BCR-project a method ofcalibrating stress grading machines is developed.

In a field test glued pieces of wood are exposed toSwedish outdoor climate. Different types of glue areused and the pieces have been subjected to varioustypes of surface treatment. The results can be usedfor classifying the glues and the surface treatmentsand also for calibrating laboratory methods againstreal exposure conditions.

Research regarding frost and scaling resistance ofconcrete is established since a number of years. Atest method has been developed which today isaccepted as a standard test method in Sweden. In anewly started project the frost resistance of oldconcrete structures will be studied. This will, amongother things improve the possibility to predict theservice life of new structures.

In a field exposure test on the Swedish west coastabout 50 concrete qualities are tested in a marineenvironment. This is a joint project where beside SPalso LTH (Lund University of Technology), CTH(Chalmers University of Technology) and CBI(Swedish Cement and Concrete Research Institute)participate. The aim of the project is to test new typesof concrete, to calibrate existing test methods andmaterial models and to develop new material mod-

els. Of special interest is chloride penetration andfrost resistance.

Concrete mortar and other inorganic materialsare studied by using microscopical methods. In aEUROCARE-project mortar from up to 1000 yearsold churches are studied, mainly by microscopicalmethods but also by chemical methods and by usingstrength and durability testing. The aim of the projectis to learn from the past in order to improve theproperties of the mortars produced today.

AddressSwedish National Testing and Research InstituteP.O. Box 24036S-400 22 Göteborg, Sweden

Phone+46 312008 70Fax+46 31 1612 95

StaffSenior membersLars Boström Doctor of ScienceKentGylltoft ProfessorCarl-Johan Johansson Licentiate of TechnologyPer-Erik Petersson Doctor of ScienceBjörn Schouenborg PhDLennart Ågårdh Associate professor

Major instrumentation• MFL UP2000 compression testing machine,

1977, with a load capacity of 20 MN static and13 MN dynamic (1 Hz).

• Instron 1253 universal strength testing ma-chine, 1977, with a load capacity of 50 kNdynamic and 100 kN static.

• Cook-Bolinder stressgrading machine 1991;prediction of bending strength of timber withsizes up to 75 x 250.


SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - BUILDING TECHNOLOGY

Computer Matic strcssgrading machine 1991;prediction of bending strength of timber withsizes up to 75 x 150.

Micromeritics X-ray SediGraph 5100,1991;determination of grain size distribution ofpulverized materials with particle size between300 and 0,1 mm (equivalent spherical diam-eter). Materials commonly analysed are limingmaterials, cement and additives, aggregatefiller and industrial minerals.

Leitz Polarizing microscope, 1978, withInnovativ Vision AB LabEye Image-analysissystem 3,1992; thin-section analysis of build-ing materials and quantitative analysis of air-pore structure and size distributions of variouscomponents in concrete.

Financial support• The Swedish Board for Building Research, BFR•NORDTEST•NUTEK•BCR• Swedish materials industry• Swedish National Road Administration•SBUF• Nordisk Industrifond

Research projectsMachine stress grading of timberMachine stress grading is a technique where thetimber is classified based on a prediction of thestrength. The most common method is to determinethe bending stiffness and to use known relationsbetween strength and stiffness. In the most commongrading machines the timber is subjected to threepoint loading in the weak direction and the load-deflection relation is determined for every 100 to 150mm along the timber except for 0.6 m at the ends.

In our project we study different ways of improv-ing the strength prediction. This, for instance, in-volves adding information about knot size usingoptic sensors and image processing technique. Oneimportant task is also to find methods of damping thevibrations that easily occur in the timber during thepassage through the machine and that affects thestrength predictions.

Newmethodsarealsostudied, for instance strengthpredictions based on a combination of density andknot size measurements. In a European co-operationproject (BCR) we are developing calibration sys-tems for stress grading machines.

Traditionally timber has been graded in dry con-dition. The economy could, however, be improved ifthe grading was carried out prior to the rather costlykiln drying as no drying of the rejects would benecessary then. In our project we establish the rela-tion between strength and stiffness for wet timber inorder to obtain correct setting values for the ma-chines.

Structure and composition of old lime mor-tars and renderings with good durability;examination, sampling and analysisThe knowledge for choosing methods and materialsfor restoration and conservation of the architecturalheritage is not always available.

Nordic Lime is a joint inter-Nordic project on oldbuilding limes. The primary aim of the project is todevelop new lime mortars mainly for conservationpurposes. The project also deals with the develop-ment of guidelines for field examination and sam-pling. The project will also increase our knowledgeabout which properties that have a major influenceon the durability of present mortars and renderingsfor other building purposes.

Three medieval churches in Scania have beensampled in order to study the structural, chemical,physical and mechanical properties of ancient mor-tars and to correlate these parameters with a.o. thedurability against frost action.

Well established methods for testing of frostresistance, compressive strength, density, porosity,water absorption coefficient and permeability aremodified to suit the small-scale samples of the oldmortars. Chemical analysis and thin-sectionmicroscopy are used in order to characterise thechemical composition of the binder phase and thecomposition of the aggregates. Image-analysis isused to quantify the air-pore content and structureand also the content of aggregate versus the binderphase.

A progress report with results from the ongoinganalyses will be submitted in the spring, 1993. Theproject will thereafter focus on the development of

258 THE CENTRE FOR

SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - BUILDING TECHNOLOGY

methods for testing objects in situ and the manufac-turing of new mortars, short time testing (acceleratedageing) and field applications.

Frost resistance of concreteTo rate the salt-frost resistance of concrete the Swed-ish standard 13 72 44 has proved to be very depend-able and to give reproducible results. It is a laboratorymethod where the resistance of the concrete is as-sessed after the amount of material that has scaledafter a number of well-defined freeze-thaw cycles.

However, the method is sometimes consideredtoo strict and to give results with a large margin ofsafety. Consequently, concrete structures might be-come unnecessarily expensive. The reason for thesedoubts is that nobody has taken pains to correlate theresults to outdoor circumstances.

To ascertain the relevance of the method, i.e. toshow how the accurately defined freeze-thaw cyclesof the standard correspond to outdoor conditions, itis necessary to expose concrete to aggressive envi-ronments outside the laboratory. For this purposefield stations have been established, the largest oneat Träslövsläge on the Swedish west coast. Thisstation, which was inaugurated in December of1991, consists of two connectal pontoons. Along thesides of the pontoons, concrete slabs of more than 40different qualities are fastened, half-way subwezedinto the water. The slabs are provided wilh reinforce-ment. Temperature, wind velocity, humidity and

precipitation are recorded and studies will be madeof frost resistance, chloride penetration, alkalinityand rate of corrosion.

Normally freeze-testing starts in the laboratorywhen the concrete is 28 days old. Results from thesetests cannot be expected to be in full agreement withresults obtained from drilled-out cores from oldstructures. A procedure or formula to "translate"laboratory results to safe predictions of concretedurability in aggressive environments is highly de-sirable and work is in progress with this purpose.

Laboratory experiences with the freeze-testingmethod are quite extensive as regards testing with asalt solution (3 % sodium chloride). This is not thecase, however, when freezing takes place in purewater. Comparisons with other freeze-testing meth-ods are necessary to arrive at a recommended methodfor testing and to put forward relevant assessmentcriteria for concrete in moderately aggressive envi-ronment.

The relations between various parameters thatgovern the frost resistance of concrete are poorlyunderstood. These parameters might be the water-cement ratio, air content, size and distribution of airbubbles, cement content and type of cement. Workhas started with the aim to increase the knowledge ofrelations between these parameters, hopefully re-sulting in considerably increased capabilities in de-sign for concrete durability.


Productionand materialsprocessingProduction Engineering 262IVF, The Swedish Institute



Production EngineeringDivision of Manufacturing Engineering

AddressDepartment of Production EngineeringChalmers University of TechnologyS-41296 Göteborg, SwedenPhone+46 31 772 1270Fax+46 31 772 3819

StaffSenior Members:Ralph CrafoordHans VogtJacek Kaminski

Graduate Students:Robert OhlssonChristian QjmertzMagnus JonassonBengt-Göran RosénPerÖhlHans-Börje Oskarson

Technical Staff:RolfNoniströmDick Olofsson

Secretary:

ProfessorDocentTech.Dr.

Civ.Eng.Civ. Eng.Civ.Eng.Tech.lic.Tech.lic.Tech.lic.

Eng.Eng.

Ann-Charlotte Hansson

Major Instrumentation• 525 ton hydraulic r•™;ss. Manufacturer:

Carbox. Field of application: High pressureresearch, cold forging.

5 axis milling machine. Manufacturer: Maho.Field of application: Milling, tool wear, adap-tive control.

Surface roughness measurement equipment.Rebuild for 3D measurements.

Major Reids of ResearchA: Maching and tool wear

participants: Ralph Crafoord, Jacek Kaminski,Per Öhl, Hans-Börje Oskarson, Hans Vogtcollaborators:SKF (Swedish Ball BearingCompany)

B: Surface roughnessparticipants: Ralph Crafoord, Bengt-GöranRosén, Robert Ohlsson, Magnus Jonassoncollaborators: Volvo Car Corporation

Research ProjectsA: Wear Mechanism when Machining with

Whisker-reinforced Ceramic Cutting Tools.This project will study the wear mechanism whencutting with whiskerreinforced ceramic cutting tools,especially in work material Inconel 718 and V2906.In part A (1990-1991) of the project the notch wearmechanism has been examined. The notch wear in aceramic cutting tool when machining heat resistantalloys is often the factor which decides the tool lifeand consequently the tool economy will be depend-ent on it. In this study, DOC notch at the whisker-reinforced ceramic (A12O3 + SiCw) will be studiedwhen turning in Inconel 718. Some comparisonstudies are made in steel V2906. The position of thenotch and the geometry of the tool are measuredclosely. The notch is situated outside the theoreticalchip width with all its extension. The friction condi-tions in the cutting area and the cutting parametershave a determining influence on the degree to whichthe notch will appear on the rake and flank face. Chipstudies are made and the chip formation mechanismis discussed. The ragged edge of the chip is animportant factor for the notch formation. The wearmechanism in the notch area is a combination ofmechanical and chemical processes. The two typesof mechanism are confirmed in SEM studies andstudiesofcuttool.Theinfluence of the oxygen on theprocess will be mentioned in wear studies withdifferent cutting media. The influence of whiskerorientation on notch wear is studied in some special

262 THE CENTRE FOR

PRODUCTION ENGINEERING

tool materials with a controlled whisker orientation.Whiskers standing all over the material flow give thebest wear resistance, while the worst wear resistancewill be given with whiskers laying all over the flowdirection of the material. Reported to NUTEK910927. In pan B (1992-1994), the time-dependentchemical reactions and wear mechanism will beexamined. Aspectsof intermittent cutting conditionswill be included in the study. FEM will be used todetermine the temperture gradient in the cuttingzone. Investigation methods such as SEM, Augerspectroscopy and element mapping will be used.Cutting tools, work material and analyzing supportwill be furnished by Volvo Flygmotor and SandvikCoromant.

B: Interactive Surface ModellingMaking surface roughness a useful tool for dealingwith functional surfaces points to the need for a high-quality foundation for surface decisions. Errors inspecifications in many cases lead to costly produc-tion and perhaps nonfunctional surfaces. Decision-makingverymuchreliesonthequality of retrievableand collected information. A recognized problemtoday is that compared to older systems, today'sindustry suffers from discontinuity in knowledgecommunication due to reorganizations and the dy-namics in the labor market. Often problems occur inmaking available proper and select information(standards, expert knowledge and laws). InteractiveSurface Modelling, ISM, addresses those problemswith an approach where functional demands controlthe route from specification of parameters throughmanufacturing preparation to measuring of the ma-chined surface.

For two years, we have been working with Volvoto build a prototype Interactive Surface Modellingsystem for expert support in specification, manufac-turing preparation, and measuring of surface rough-ness and topography. In this first version, the systemis implemented for two obviously different func-tional surfaces: cylinder liners for car engines, andleather imitation textures and (ongoing) metal sheetsurfaces for deep drawing and painting. The imple-mentation is done on an ordinary PC with the supportof commercially available softwares for databasehandling, CAD multimedia and calculations. A lotof effort has been put into making the system user-friendly. Demonstrations to industry and other uni-versities in Sweden, Denmark and Great Britain

have confirmed the usefulness of our ISM-concept.In cooperation with Volvo and NUTEK, we in thesurface measuring group till continue our work withISM to increase the quality of the basic knowledgefund for the cylinder liner surface with the focus onthe manufacturing process.

PublicationsPh.D. DissertationsBengtsson, Anders, On Three-Dimensional Measurement

of Surface Roughness. September 1991.Kaminski, Jacek, Positional Accuracy of Drilled Holes.

December 1992.

Licentiate DissertationsRosén, Bengt-Göran, Interactive Surface Modelling and

Representation of Surface Roughness and Topography.November 1991.

Oskarson, Hans-Börje, Wear Mechanism when Machiningwith Whisker-reinforced Ceramic CuttingTools (inSwedish). December 1991.

Ohl, Per, Harder Ball Surfaces: Thermal and MechanicalProcesses (in Swedish). October 1992.

Papers1) Rosén, B-G. and Crafoord, R., "Interactive Surface

Modelling. Model of a Function-Oriented ExpertSystem for Specification of Surface Properties",Industrial Metrology, Vol. 2 No. 2,1992 pp. 107-119.

Rosén, B-G., "Representation of Thrcc-DimensionalSurface Topography in CAD-Systems and Image-Processing Software", Machine Tools and Manufac-ture, Vol. 12,1992.

2) Planning Expert". Proceedings of the CIRP Seminars -Manufacturing System 20(1991)1, WISU Verlag,Aachen, 1991 ISSN 0176-3377.

Vogt, H.G., "Skiktbeläggningar på verktyg - någrafysikaliska synpunkter vid skärande bearbetning",CTH, Inst f Produktionsteknik, Verkstäderna (1992)Oct. 1992, Stockholm.

Vogt, H.G. and Zaring, P., "Planning of Operation Se-quences with an Al-based Knowledge-AquisitionTool", in Kochan, D., Complex Machining and AI-methods. Proceedings of the IFIP TC5/WG5.3 Work-ing Conference, 27-29 Nov. 1991, Gaussig/Drcsden,Elsevier, Nov. 1991, ISBN 0^44-89326-1.

Crafoord, R., "Proposal for a Fast and Accurate Softwarefor Sheet Metal Bending", ERC/NSM Report, OhioState University, Columbus OH, USA, Dec. 1991.

Crafoord, R. and Lee, J.K., "Bending Experiments",Engineering Mechanics, Ohio Stale University,Columbus OH, USA, Jan. 1992. NADDRG Confer-ence, May, 1992.


1 V 1 % The Swedish Institute of Production Engineering Research

IVF - The Swedish Institute of Production Engi-neering Research - was founded in 1964 and con-ducts applied research and technological develop-ment. The objective is to improve the efficiency andcompetitive strength of engineering companies bydeveloping and disseminating new technologicalknow-how. IVF has a turnover of SEK 105 million(about 10 MGBP) and has 180 employees (1992).

IVF's main work consists of• monitoringandevaluatinginternationaldevelop-

ments in the engineering industry;

• initiating and implementing research projects inclose co-operation with industry and other re-search institutes, both nationally and interna-tionally;

• turning technological advances into practicalapplications;

• helping to introduce new technology in indivi-dual companies;

• spreading information about new methods ofproduct development and production engineering- particularly to small and medium-sizedcompanies.

IVF perform works within the following areasMachiningAssemblyRoboticsCAD/CAMElectronicsForgingHot isostatic pressingHeat treatmentWeldingSurface treatmentSheet metal workingNew materialsincluding composite fibres

Two of these areas, "Electronics" and Surface treat-ment", are described more in detail below.

AdhesivesQuality managementWorkingenvironments researchVibrationVentilationWorkplace planningErgonomicsMachine safetySmall companiesservice

AddressThe Swedish Institute of Production EngineeringMölndalsvägen 85S-412 85 Göteborg, SwedenPhone+46 31 83 8600Fax 446 31 40 78 76

The department ofElectronic ProductionThe department of Electronic Production consists of18 employees of which 15 are research engineers (7Ph.D.s, 7 engineers holding M.Sc. degrees and 1engineer). The research volume is SEK 15 •nillion.More than 70 companies support (financially andtechnically) joint projects conducted by the depart-ment of Electronic Production. Manager of the de-partment is Ph.D. Bill Brox.Five areas are identified as main research areas.

A: Support for design, M.Sc. Håkan SvärdB: Assembly and materials technique,

M.Sc. Per HedemalmC: Material and failure analyses,

M.Sc. Göran WetterD: Chemistry and environment,

Ph.D. Per-Erik TegehallE: Production, Engineer Peter Wahlberg

Major equipmentThe laboratory facilities consist of a micro joininglab in a clean room, surface mount lab, thermal lab,chemical and specimen preparation lab, environ-mental testing lab, material analysis lab and lab forchemical analysis. This includes

• Scanning Electron Microscope, SEM, JEOL840 A, resolution approx. 50 Å, test object sizemax. 10 cm.

• Energy Dispersive Spectrometer, EDS,TRACOR, connected to the SEM equipmentfor quantitative and semiquantitative elementalanalysis (also carbon, oxygen and nitrogen).

264 THE CENTRE FOR

IVF THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

5 - Sulfat

I I I I I I I I I I I

5 6Minutes

i i i i 1 1

8 10Diagram fromion chromatograph

Ion chromatography, Dionex 300, with con-ductivity detector and spectral array detector.Computer controlled.

Production equipment, such as IR reflowsoldering equipment, semiautomatic screenprinter, wedgebonder, ballbonder and pull andshear tester.

Environmental testing equipment, such astemperature cycling chamber, humidity cabi-nets and pressure cooker.

X-ray microscope, Feinfocus FXS 200.72.Real time X-ray with image processing. Accel-eration voltage 10-200 kV. Resolution approx.3 pm. Penetration thickness 20 mm Fe, 80 mmAl. Test object size: max. 0,5 m, 10 kg.

Thermo camera, Agema Thermovision 870.Resolution approx. 15 |jm, sampling time 70ms, temperature sensivity 0,1 K.

ProjectsBelow are examples of projects ongoing within thedepartment that in some respects are related to thefield of materials science.

A l : EMCSeveral projects are ongoing in this area whichincludes the electromagnetic interaction betweenthe electronics and the surroundings as well as theelectrical properties of materials.

A2: Thermal design and cooling of electronicsThermal parameters of individual components,printed circuit boards and electronics installed inracks have been studied for many years at the depart-ment. Today, much attention is focused on thermalparameters of different materials.

B l : International programme for Rip-ChipInterconnection Technique

Flip-chip is a technique to mount chip directly ontothe printed wire board instead of using components.The project includes evaluation of the reliability fordifferent cowibinations of materials. The evaluationitself consists of e.g. strength tests and environ-mental tests.

Surface mounted chip capacitor - voids in solder joint.


iVF, THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

B2: Conductive adhesives as solder replacementThe driving forces to use adhesives as replacementfor solder is higher reliability of printed circuitboards, no use of lead (environmentally hazardous),fewer process steps in the production of electronics.

Dl : The International conformal coating

The objective is to increase the reliability of printedcircuit board assemblies using conformal coatings atminimal additional cost The evaluation includes theproperties of the conformal coatings in differentenvironments, the influence of the surface statebefore coating as well as the influence of method ofapplication.

D2: Evaluation of commercially available electrolessly golcHXated printed circuit boards

The main purpose of the project is to evaluate theproperties of electrolessly plated FR-4 PCBs madeby different manufactures using different processes.The project includes evaluation of thickness, hard-ness, porosity, strength, solder ability, bond ability,environmental tests as well as analyses of intermetallic phases in the solder joint.

Publications1 Handbok i lermisk konstruktion av elektronik i

apparaimiljö. Göran Rodman och Anders Sihlbom,IVF-skrift 88822,1988,258 sidor.

2 Elektrisk dimensionering av kretskort. Strålning -regler och hjälpmedel. Hakan Svärd, IVF-rcsultat 90622,199C. 51 sidor.

3 Concurrent Engineering - Resultat och utvärdering avenkät. Peter Gustafsson och Håkan Svärd, IVF-skrift92818.1992,48 sidor.

4 Polymer (hick film technology - A reliability study ofan additive PCB technology. Per Johnsson, JanEliasson and Martin Udden, IVF-rcport GE9OO4,1990,134 pages.

5 Mot miljövänligarc elektronik - avveckling av b!y ochbromerade flamskyddsmedcl. Per Hedemalm, IVF -skrift 91823,1991,30 sidor.

6 Chip-on-boarc' - Grundläggande teknik för trådboiidadchip-on-board. Anne Tillström, IVF-skrift 91831,1991,70 sidor.

7 Flexibel och kostnadseffektiv teknik för framställningav metallkontakter hos chip - Nya sätt att skapa bumparför flip-chip-förbindningar. Johan Liu, IVF-rapport91025,1991,52 sidor.

8 Mciallmigralion mellan uttag på elektronikkomponentermed liten bendelning. Per Johnsson och Anne Tillström,IVF-resultat 91602,1991,28 sidor.

9 Brandskadad elektronik: Sanering och tillförlitlighetBEST-projektet Lennart Cider, IVF-rapport 92/20,1992,34 sidor.

10 The relation between the halide and alkali concentra-tions and the electrochemical migration on printedcircuits boards. Per Carlsson and Lennart Cider, 2ndInternational symposium on corrosion of electricmaterials and devices. Electrochemical SocietyConference, Toronto 1992.

11 TAB outer lead bonding alternatives for small batchand flexible production. Martin Udden, IVF-skrift90814,1990,40 pages.

The Surface Treatment groupThe Surface Treatment group consists of 12 employ-ees of which all are research engineers (1 Ph.D., 1M.Sc, 6 engineers holding M.Sc. degrees and 4engineers). The research voiume is SEK 7 million.More than 60 companies support (financially andtechnically) joint projects within the Surface Treat-ment group. Manager of the department includingthe Surface Treatment group is M.Sc.Lic Per Boije.

Three areas are identified as main research areas.A: Electroplating/Hot dip galvanizing

(M.Sc. Richard »c.glund)B: Painting (M.Sc. Lars Österberg)C: Thermal spraying (M.Sc. Lars Österberg)

Major equipmentThe lab facilities consists of chemical surface treat-ment equipment (pilot scale), industrial productionequipment for painting and thermal spraying besidesanalyses facilities already mentioned. This includes

• Pilot Plating Plant, flexible and fully auto-mated with bathes 70 1401.

• Pilot Painting Fac u for powder and wetspray painting.

• Thermal Spraying Faci fy, including HVOF(High Velocity Oxygen 1 ucl).

266 THE CENTRE FOR

IVF, THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

IVF:s flexible,fully automatedpilot plant

Surface Carbon Analyzer (IMC-method).Atomic Absorbtion Spectroscopy.SCAB Corrosion Testing

ProjectsBelow are examples of the about 30 major projectsongoing within the group that in some respects arerelated to the field of materials science.

A l : Quality assurance in surface treatment MustyThe work covers how to build quality systems insmall surface treatment companies. An importantfield is to investigate how different process param-eters influence the properties of the coating.

A2: Hard chromium withIncreased corrosion resistance

The main interest has been to optimize the param-eters in the hard chromium process in order to gethard and wear resistant coatings with good corrosionprotection.

It has been shown that pulse plating increases thecorrosion protection with a very small drop in hard-ness. The i r cs for causing blistering in the coatingwhen using wetting agents in the bath have beenstudied. The main result is that the hard chromiumprocess is tolerant to relatively hifcii amounts ofwetting agents.

B l : Powder coating for corrosion protectionThe ability of a powder paint film to act as a barrierto the environment has been studied. Among theparameters which can be changed during the appli-cation of the paint, the film thickness has the greatestinfluence on the water permeability. At the samefilm thickness all powder paints studied showed lesswater permeability compared with the wet paintsstudied.

C l : The adhesion of thermally sprayed coatingsThe adhesion is a critical property of a thermallysprayed coating. The study showed that when thesubstrate was properly blasted the preheating tem-perature was the most critical one. The differencebetween preheating temperature and the maximumtemperature of the substrate during spraying shall beas small as possible. In contrary to the commonopinion the influence of time between blasting andspraying was negligable.

Publications

1 Konstniktionsanvisningar för ytbehandling. (Designguide-lines for surface treatment). Lars österberg,Göran Ahlin, IVF-resuliat91604 (1901) 57 pages.

2 Yure miljö vid oorganisk ytbehandling. Vad händer pä90-talet? Lars Clarin. IVF-skrift 91816 (1991).

3 Pulvcrlackering - användningsområden. (PowderCoatings - Fields of Application). Sture Lttckner, IVF-resuliat 92501 (1992) 27 pages.

4 Renhetsmätning - en uppslagsbok om mätmetoder.(Cleanliness measurement - a reference manual ofmeasuring methods). Cecilia Norrby och Jan Skogsmo,IVF-resultat 92603 (1992) 71 pages.

5 Teknisk utvärdering av väunedlets inverkan pahårdkromskiki. (Evaluation of wetting agent on thequality of hard chromium coatings). Svante Nordänger,IVF-skrift 92815,23 pages.

6 Kvalitetssystem i ytbehandlande industri, en handbok.Richard Berglund, Ytforums Förlags AB 1992,48 sidor.

7 The journal Ytforum: 15-20 IVF-papers published eachyear.


KeywordsKeyword Chapter Page

Aadhesives IVF 264

analytical electron microscopy Microscopy and Micr analysis 228

annealing Semiconductor Physi ;s and Heterostructures.... 157

atom-probe field ion microscopy Microscopy and Microanalysis 228

B

batteries Materials Physics 70

brazing Engineering Metals 216

buckminsterfullerenes Molecular Physics 126

building materials Building Materials 246

bulk polymers Polymer Technology 78

Ccatalysis Materials and Surface Physics 2

Surface Physics 114Molecular Physics 126

catalyst Engineering Chemistry 139

ceramic materials Engineering Metal* 216

ceramics SCI 202

chlorine-free bleaching Engineering Chemistry 139

chromogenic materials Experimental Physics 32

clusters Molecular Physics 126

combustion Surface Physics 114

concrete Building Materials 246

condensed matter theory Materials and Surface Physics 2


coordination chemistry Inorganic Chemistry 46

corrosion Engineering Metals 216

corrosion chemistry Inorganic Ciunistry 46

corrosion resistance materials SCI 202

IVF 264

Ddisordered systems Materials Physics 70

durability Building Materials 246Mechanics, SP 240Building Technology, SP 257

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KEYWORDS

electrochemistry

electronic excitation

electronic calculation

electron microscopy

electron structure

electrooptics

energy related materials

energy transfer

engineering ceramics

Ffabrics

ferroelectricity

fibers

frequency doubling

fuel cells

GGaAs

glass transition

Hhard materials

high pressure

high temperature materialshigh temperaturesuperconductors

IIC-CAD

interdisciplinarymaterials research

ion conducting polymers

Inorganic Chemistry 46


Molecular Physics 126

Microscopy and Microanalysis 228

Electronic Structure of Condensed Matter 13Materials and Surface Physics 2


Liquid Crystals 164

Materials Physics 70Experimental Physics 32

Interdisciplinary Materials 26


SCI 202

IFP-TEFO 102

Liquid Crystals 164

IFP-TEFO 102


Materials Physics 70

Semiconductor Physics and Heterostructures.... 157


SCI 202


SCI 202


Solid State Electronics 148




KEYWORDS

laser spectroscopy

lattice mismatch

liquid crystals

MMBE

many-body effects

materials characterization

mechanical properties

mesoscopic systems

metal cutting

metallic materials

microanalysis

microstructurc

moisture

molecular physics

Nnanomiterstructures

nuclear magneticresonance (NMR)

0

oil refining

optical computing

optoelectronics

photoelectron spectroscopy

pollution control

polymer synthesis

polymer surfaces

polymers

powder metallurgy

processing



Liquid Crystals 164


Electronic Structure of Condensed Matter 13


Engineering Metals 216Polymeric Materials 87Mechanics, SP 240Materials and Surface Physics 2


Production Engineering 262

Engineering Metals 216




Building Materials 246



Polymer Technology 78

Engineering Chemistry 139

Liquid Crystals 164






Polymeric Materials 87Polymer Technology, SP 95

IFP-PGI 106

Engineering Metals 216

Polymeric Materials 87

270 THE CENTRE FOR

KEYWORDS

quantum structures Semiconductor Physics and Heterostructures.... 157

reaction kinetics

rheology

SSTM

secondary ion massspeci- jmetry (SIMS)

semiconductors

semiconductor surfaces

sensors

silicon devices

silicon technology

small particle technology

solid electrolytes

structural dynamics

superconductivity

superconductors

superlatticts

surface analysis

surface coating

surface physics

surface processes

surface roughness

synchrotron radiation

synthesis


Polymeric Materials 87



Semiconductor Physics and Heterostructures.... 157Solid State Electronics 148








Experimental Physics 32



Applied Solid State Physics 174Materials Physics 70

Inorganic Chemistry 46


Surface Physics 114Engineering Metals 216


Experimental Physics 32

Surface Physics 114


Surface Physics 114





KEYWORDS

textile technology

theory of materials

thermal insulation

thermal transport properties

tool wear

trace analysis

IFP-TEFO 102


Building Technology 257

Thermal Transport Properties of Materials 22



Wwood

XX-ray

Yyarns

Building Materials 246

Microscopy and Microanalysis 228Inorganic Chemistry 46Electronic Structure of Condensed Matter 13

IFP-TEFO 102

272 THE CENTRE FOR

The Centre for Materials Sciencepromotes materials research among the member organizations and

provides a link with industry and with society as a whole. Members are:

School of Physics and Engineering Physics, CTH /GUDepartment of Theoretical Physics and Mechanics

Department of PhysicsDepartment of Applied Physics

School of Chemical Engineering, CTH /GUDepartment of Inorganic ChemistryDepartment of Physical Chemistry

Department of Engineering ChemistryDepartment of Polymer Technology

School of Mechanical and Vehicular Engineering, CTHDepartment of Engineering MetalsDepartment of Polymeric Materials

Department of Production EngineeringDepartment of Theoretical and Applied Mechanics

School of Civil Engineering, CTHDivision of Building Materials

School of Electrical and Computer Engineering, CTHDepartment of Solid State Electronics


The Swedish Institute of Fibre and Polymer Technology

Swedish National Testing and Research Institute

The Swedish Institute of Production Engineering Research, IVF

The Centre for Materials ScienceChalmers University of Technology

S-412 96 GöteborgSweden

!SSN 1104-3539ISPN CTH-MC-PBS--1--SE

the centre for materials science catalogue of ......shekhter, and göran wahnström emphasizes work...

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