Jornadas

ICEMS2011Workshop

www.icems.ist.utl.pt

February 3rd - 4th

Anfiteatro do Complexo InterdisciplinarInstituto Superior Técnico

Book of Abstracts

Dear Colleagues,

Welcome to the ICEMS Workshop 2011!

ICEMS was created in 1991 by a group of researchers involved in the study and

development of novel Materials and Surface treatments and Characterization, under the

auspices of the Foundation for Science and Technology (FCT). Twenty years later, it

has gone through several re-arrangements, with the departure of groups but also with a

steady growth in other areas, both in the number of members and in its main indicators.

In spite of this evolution, there is still much to be done. We still need to reinforce the

internal links in many areas, and as we grow we also need to better integrate the

newcomers. The role of our Workshops is crucial for this purpose, as they are forums

for exchange and discussion of ideas. It is the time for us to learn from one another.

Further to the technical sessions, I must stress that we have this time open visits to the

laboratories, for which you are all invited.

Let us seize these two days of the ICEMS Workshop 2011 and open our minds to

different problems, different techniques and different approaches!

Alda Simões

Head of ICEMS

ICEMS Workshop 2011

Program, Day 1

Thursday, Feb 3rd 2011, Anfiteatro do Complexo Interdisciplinar, IST

Time # Speaker Theme

09:00 O P E N I N G S E S S I O N

09:15 1 Sónia Eugénio Cr(III)-ionic liquid solutions as electrolytes for the electrodeposition of black chromium thin films

09:40 2 José Ricardo Cezar Salgado Synergistic effect between the Pt and Pt-Ru nanoparticles and oxygenated groups on functionalized carbon for DMFC

10:05 3 Bin Li Plasticity and fatigue behaviour measurements of structural materials under biaxial loading conditions

10:30 4 Ruben D.R. Ramalho Electrically aligned microtubules: bridging the gap from life to electronics

10:55 C o f f e e b r e a k

11:15 L A B O R A T O R Y V I S I T S

13:15 L u n c h b r e a k

14:45 5 Ricardo Réfega Multifunctional nanoparticles for biomedical applications

15:10 6 Paulo Saturnino Direct borohydride / hydrogen peroxide fuel cell

15:35 7 Teresa Santos Treatment of ceramic tiles with different polymers

16:00 C o f f e e b r e a k

16:20 8 Carina Rodrigues Mass-transfer entrance effects in spacer-filled channels of spiral-wound modules

16:45 9 Arne Lüker Sol-gel derived ferroelectric thin films for voltage tunable applications

17:15 L A B O R A T O R Y V I S I T S

Laboratory Visits for Thursday, Feb 3rd 2011

Time Laboratory Location

11:15 – 13:15

Semiconductor and Energy Conversion Lab Complexo Interdisciplinar, piso 6, sala 605

Mechanical Testing of Materials Lab Pav. Mecânica II, cave

MicroLab – Electron Microscopy Lab Pav. Mecânica II, sala 1.40

17:15 – 18:15 Laser Surface Processing Lab FCUL, Edifício C8, piso 4, sala 8.4.01

ICEMS Workshop 2011

Program, Day 2

Friday, Feb 4th 2011, Anfiteatro do Complexo Interdisciplinar, IST

Time # Speaker Theme

09:00 10 Paulo Gonçalves Venâncio Corrosion sensors for aluminum alloy airframe

09:25 11 Artur Bento HDPE/mesoporous silica nanocomposites by ‘in-situ’ polymerization

09:50 12 Gonçalo Monteiro Optical properties of germanosilicate and germanotellurite glasses

10:15 13 Anandkumar Ramasamy Wear resistant Al-12Si/TiB2 coatings produced by laser cladding

10:40 C o f f e e b r e a k

11:00 14 Vitor Anes Design and assembly of an ultrasonic fatigue testing machine

11:25 15 Soumya R. Bhattacharya Synthesis and characterization of GaN thin films

11:50 16 Mónica Faria Sub-micron tailoring of bi-soft segment asymmetric polyurethane membrane surfaces with enhanced hemocompatibility properties

12:15 17 A. J. Silvestre Ferromagnetic order in aged Ti1-xCoxO2 nanoparticles

12:40 L u n c h b r e a k

14:15 L A B O R A T O R Y V I S I T S

16:15 F I N A L M E E T I N G

Laboratory visits for Friday, Feb 4th 2011

Time Laboratory Location

14:15 – 16:15

Membranes Lab Torre Sul, piso 10, sala 10-6.6

Polymer Synthesis Lab Torre Sul, piso 9, sala 9-6.13

Raman and IR Spectroscopy Lab Pav. Física, piso -1, salas 01-5.7/5.9

Auger and XPS Spectroscopy Lab Pav. Física, piso -1, sala 01-5.1

Semiconductor Deposition by PLD Lab Pav. Física, piso 5, sala 5-1.17

AFM Lab Pav. Física, piso 3, sala 3.8-2

ICEMS Workshop 2011

Abstract #01

Cr(III)-ionic liquid solutions as electrolytes for the electrodeposition of black chromium thin films

S. Eugénio1; S. Quaresma1; C. Rangel1,2; R. Vilar1

1 ICEMS & Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa,

Portugal 2Laboratório Nacional de Energia e Geologia, Fuel Cells and Hydrogen Unit, Paço do Lumiar 22,1649-038 Lisboa,

Portugal e-mail: s.eugenio@ist.utl.pt, silvia.quaresma@ist.utl.pt, carmen.rangel@lneg.pt , rui.vilar@ist.utl.pt

Black chromium is an important coating material used in solar thermal systems as a spectrally selective surface. This coating is usually obtained by electrodeposition from sulphate free chromium (VI) aqueous solutions which represent a health and environmental hazard. Developments in green chemistry have shown that ionic liquids can be used as electrolytes, due to their wide electrochemical window and enhanced chemical stability when compared to water, allowing the deposition of a wide range of materials. In this study, a trivalent chromium-ionic liquid (Cr(III)-[BMIm][BF4]) solution was investigated for the electrodeposition of black chromium thin films. Cyclic voltammetry and chronoamperometry were used to study the electrochemical behaviour of the electrolyte. Electrodeposition of black chromium thin films was carried out several substrate materials, by a potentiostatic method. The coatings were characterized by SEM/EDS, XPS, XRD and TEM. Cyclic voltammetry allowed the identification of the potential range for the reduction of Cr(III) ions in solution and their diffusion coefficient in [BMIm][BF4] was estimated from cyclic voltammetry and chronoamperometry data. Homogeneous black chromium coatings were obtained on stainless steel, carbon steel and copper substrates (Fig. 1). The films present a sub-micrometric granular structure (Fig.1). EDS chemical analysis showed that the main elements present in the coating are Cr and O. XPS analysis confirmed the presence of Cr oxides and metallic Cr. XRD and TEM results show that the coating material is amorphous. After annealing in vacuum at 873 K, the deposited material crystallizes as Cr2O3, with a crystallite size of 17 nm.

Fig. 1: Scanning electron micrographs of black chromium coatings electrodeposited from Cr(III)-[BMIm][BF4]

solution on (a) stainless steel, (b) carbon steel and (c) copper.

Acknowledgement: This work was financially supported by Fundação para a Ciência e Tecnologia (FCT) under the project PTDC/CTM/68847/2006. Sónia Eugénio acknowledges a PhD grant from Fundação para a Ciência e Tecnologia (FCT).

ICEMS Workshop 2011

Abstract #02

Synergistic effect between the Pt and Pt-Ru nanoparticles and oxygenated

groups on functionalized carbon for DMFC.

J.R.C. Salgado1, R.G. Duarte1,3, L.M. Ilharco2, A.M. Botelho do Rego2, A.M. Ferraria2, V.A.

Paganin4, E.R. Gonzalez4 and M.G.S. Ferreira1,5

1ICEMS, 2CQFM and IN, IST, Universidade Técnica de Lisboa, Av. Rovisco Pais, S/N, 1049-001, Lisboa,

Portugal. 3Instituto Politécnico de Setubal, ESTBarreiro, R. Américo da Silva Marinho, 2839-001, Barreiro, Portugal.

4IQSC, Universidade de São Paulo, Campus São Carlos CP 780, 13560-970, São Carlos, SP, Brazil. 5CICECO, Universidade de Aveiro, Campus De Santiago, 3810-193, Aveiro, Portugal.

There is a great interest in low temperature fuel cells because they allow autonomous production of the clean electric energy by oxidation of the fuel and of the O2/air reduction. Nevertheless, the economic aspects and environmental of the direct methanol fuel cell (DMFC) has to be previously considered. As a relatively new technology, there has been never produced in series and the cost of entrance in the market is very high. Therefore, research and development of new materials for the electrocatalytic reactions in DMFC are of great importance for the viabilization of these systems. In this direction, the objective of this work will be the synthesis of electrocatalysts supported on carbon with different chemical treatment and thermal (Pt/C and Pt-Ru/C) for the methanol oxidation reaction in the fuel cell. Thus, this report consists of obtaining electrocatalysts by an adequate method and to characterize them physically by XRD, SEM, XPS, FTIR, XRD, HR-TEM techniques, and in CV, CR, EIS techniques and in low temperature fuel cell unit (DMFC).

ICEMS Workshop 2011

Abstract #03

Plasticity and Fatigue Behaviour Measurements of Structural Materials under Biaxial Loading Conditions

B. Li1, R. Cláudio2, L. Reis1 and M. de Freitas1

1ICEMS & Dept. of Mechanical Engineering, Instituto Superior Técnico

1049-001 Lisboa, Portugal 2Dept. of Mechanical Engineering, Escola Superior de Tecnologia de Setúbal

Campus do IPS, Estefanilha 1, 2910-761 Setúbal, Portugal

Biaxial tests are needed to approximate as much as possible the conditions that materials may be subjected to in practice. These tests are also necessary to quantify and clarify the effects of stress biaxiality on monotonic and cyclic loading. Furthermore a critical comparison of predictions of a material model with experimental results may suggest directions for further improvement in constitutive law. The objective of this paper is to review the biaxial experimental methods in the literature and introduce a new development on biaxial testing system.

Generally, there are two typical types of specimens for biaxial testing: tubular specimen or cruciform specimen. This paper compares the advantages and disadvantages of the two specimen types, and the applicability of each specimen type is highlighted. A new biaxial testing system is now under development in the group of Prof. Freitas, financed by a FCT project.

The focus of present presentation is to introduce the design of the cruciform specimens. In order to reach uniformed stress and strain fields in the centre section of the cruciform specimens, finite element method is used to optimize the specimen geometry. In addition, the deformation and fatigue behaviour of the cruciform specimens are simulated and discussed.

ICEMS Workshop 2011

Abstract #04

Electrically aligned microtubules: bridging the gap from life to electronics

Ruben D. R. Ramalho2,3,4, Luís Viseu Melo1,2, Maria Helena Soares3,4,5

1ICEMS, Av. Rovisco Pais 1, 1049-001 Lisboa 2Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa

3Instituto Gulbenkian de Ciência, R. Quinta Grande 6, 2780-156 Oeiras 4Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1149-016 Lisboa

5Escola Superior de Tecnologia da Saúde de Lisboa, Av. D. João II, Lote 4.69.01, 1990 - 096 Lisboa. The cytoskeleton is a set of interacting protein filaments, responsible for maintaining the cell’s structure and shape, as well as allowing for its compartmentalization and intracellular transport. The largest of the three main types of eukaryotic cytoskeletal filaments are microtubules, which participate, for example, in intracellular transport (acting as “tracks” for motor proteins), cellular motility (as key components of cilia and flagela) and cellular division (by assembling in to a mytotic spindle which segregates chromosomes). Microtubules are hollow cylinders of alpha-beta tubulin dimers, assembled in a parallel fashion which makes the overall structure polar. Microtubules have a few interesting properties from the viewpoint of nanotechnology: they interact (directly or through intermediates) with many proteins and organelles, and in some cases, as with dyneins and kinesins, can even constrain their position and direct their movements. It is, therefore, likely that the ability to control their position and properties could lead to their use as intermediates in the manipulation and use of biomolecules. Based on the polarity of these structures, we have succeeded in using high-magnitude electric fields to align microtubules, assembled in vitro from purified tubulin, on appropriately functionalized surfaces [1]. As a refinement of this technique, the same experiment was attempted using microfabricated surfaces to allow localized control. We are currently in the process of testing this approach as a way to control the movement of motor proteins. References: 1. Ramalho RR, Soares H, Melo LV. “Microtubule behavior under strong electromagnetic fields” Materials Science and Engineering: C. 2007;27(5-8):1207-1210.

ICEMS Workshop 2011

Abstract #05

Multifunctional nanoparticles for biomedical applications

Ricardo Réfega, M. Clara Gonçalves, Luis Fortes, R. M. Almeida

ICEMS & Departamento de Engenharia Química e Biológica, Instituto Superior Técnico, Av. Rovisco Pais,1049-

001 Lisboa, Portugal

This work is concerned with the development and characterization of Er3+/Yb3+-doped hollow spheres (HSs) prepared by sol-gel processing, based on core-shell (CS) structure of a sacrificial polystyrene (PS) core and a silica shell. Transmission electron microscopy (TEM) micrographs confirm the typical core-shell structure obtained.

Photoluminescence (PL) measurements on HSs doped with varying concentrations of Er3+ and Yb3+ show up-conversion phenomena after excitation at 975 nm, through the emission of blue (4F7/2, at ~ 490 nm), green (2H11/2 and 4S3/2, at ~ 523 nm) and red (4F9/2, at ~ 655 nm) light. The green luminescence (2H11/2 4I15/2 and 4S3/2 4I15/2) was the strongest emission observed. The co-doping effect related to the sensitization of the Er3+ up-conversion PL by the Yb3+ ions has been studied; both the Yb3+ Er3+ energy transfer at 975 nm and the corresponding energy back-transfer phenomena are discussed.

These RE-doped HSs might be of use in biomedical applications, e.g. bio-imaging or photodynamic therapy, since silica is biocompatible, the exciting radiation falls within the optical transparency window of living cells and tissues (600-1300 nm) and their up-conversion PL emission can be detected beneath the skin for bio-imaging purposes.

ICEMS Workshop 2011

Abstract #06

Direct borohydride / hydrogen peroxide fuel cell

P.G. Saturnino, D.M.F. Santos*, C.A.C. Sequeira, R.F.M. Lobo

ICEMS &Instituto Superior Técnico, TU Lisbon, 1049-001 Lisboa, Portugal *diogosantos@ist.utl.pt

Direct Borohydride Fuel Cells (DBFCs) are receiving increasing attention during the last decade [1,2]. The DBFC offers several advantages over the traditional Proton Exchange Membrane Fuel Cell (PEMFC) and Direct Methanol Fuel Cell (DMFC). These include higher energy density, simplified fuel handling and storage, and less toxicity of fuel and products. Most of the current research on DBFC’s is focused on those operating on sodium borohydride (NaBH4) as the fuel and hydrogen peroxide (H2O2) as the oxidant [3,4].

In the present work, a direct NaBH4/ H2O2 fuel cell consisting of a Platinum (Pt) anode, a Prussian Blue (PB)-coated Pt cathode, and a Nafion N117 membrane as the separator, was assembled. PB has been selected because of being recently reported as a mediated electron-transfer cathode catalyst in such direct NaBH4/ H2O2 fuel cells [5].

The influence of different operational conditions, namely the fuel (NaBH4 + NaOH) and oxidant (H2O2 + HCl) individual ratios and concentrations, and the cell temperature, on the performance of this DBFC were investigated. The obtained results were properly evaluated and analysed. The most suitable compositions for the operation of a NaBH4/ H2O2 fuel cell are proposed.

[1] J. Ma, N.A. Choudhury, Y. Sahai, Renew. Sustain. Energy Rev. 14 (2010) p. 183. [2] B.H. Liu, Z.P Li, J. Power Sources 187 (2009), p. 291. [3] D. Cao, D. Chen, J. Lan, G. Wang, J. Power Sources 190 (2009), p. 346. [4] D.M.F. Santos, C.A.C. Sequeira, J. Electrochem. Soc. 157 (2010), p. B13. [5] G. Selvarani, S.K. Prashant, A.K. Sahu, P. Sridhar, S. Pitchumani, A.K. Shukla, J. Power Sources 178 (2008), p. 86.

ICEMS Workshop 2011

Abstract #07

Treatment of ceramic tiles with different polymers

Teresa P. Santos1,2, M. Fátima Vaz1, A.P. Carvalho2

1ICEMS & Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa,

Portugal 2CQB, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1149-016 Lisboa, Portugal

This study follows previous works by the same authors on tiles conservation, which is an important cultural issue, particularly for South Europe. The effect of three different acrylic polymers applied as protective materials on ceramic tiles was evaluated on the mechanical and water absorption properties. An important aim is to reduce the amount of consolidation polymer, in comparison with the quantity used, generally, by the restoration departments of museums, where is common the use of a 10 % (w/v) solution of Paraloid B-72 in acetone.

The ceramic tiles analysed were handmade manufactured by Fabrica de Sant’Anna (Portugal) following a 18th century procedure, in an attempt to reproduce the behaviour of old tiles.

Three protective products were used, namely Paraloid B-72 (polyethyl methacrylate-co-methyl acrylate, 70/30) Elvacite 2046 (n-butyl methacrylate and iso-butyl methacrylate 60/40) and Elvacite 4067 (iso-butyl methacrylate). The application method selected was immersion. Polymers were applied as dilute solution of acetone, on which the amount of polymer was changed between 1 and 10% (w/v). With Paraloid B-72, one and two immersion treatments were made. Water absorption tests allowed the determination of the water absorption coefficient, the maximum water content and the open porosity. Four point bending tests were carried out to assess the protection effectiveness on the bending strength. Scanning electron microscopy observations were also performed.

Concerning the use of Paraloid (10 % (w/v)), the results showed that a second immersion does not improve significantly the mechanical properties. Water absorption tests also indicate that there is no benefit in performing a two steps methodology. On the other hand, the hydrophobic and mechanical properties of the tiles are not reduced with the decrease on the amount of Paraloid from 10 to 5%. Nevertheless, a further reduction on the concentration to 1%, either with Paraloid or Elvacite products, did not show any benefits in what concerns the open porosity, maximum water content and bending strength.

Electron microscopy analysis showed that, while for Paraloid B-72 the polymer is uniformly disperse, the Elvacite protective products do not give rise to an homogeneous coating.

As a general conclusion, it was found that the amount of consolidation products may be reduced without affecting the mechanical and water absorption properties of the ceramic tiles. A reduction of the amount of organic materials will result in a more economical and environmental friendly procedure.

ICEMS Workshop 2011

Abstract #08

Mass-transfer entrance effects in spacer-filled channels of spiral-wound modules

Carina Rodrigues1, José Santos2 and Vítor Geraldes

1, 3 ICEMS & Departamento de Engenharia Química e Biológica, Instituto Superior Técnico, Universidade Técnica

de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal 2 REQUIMTE/CQFB, Department of Chemistry, Faculdade de Ciências e Tecnologia, Universidade Nova de

Lisboa, 2829-516 Caparica, Portugal

The study of the flow and mass-transfer in narrow rectangular channels filled with spacers is of particular interest for the performance analysis of spiral-wound membrane modules. The simulation of this system by computational fluid dynamics (CFD) has been performed assuming that the flow is periodic in a repeating cell of the spacer, and experimental data has supported this approach. Regarding the CFD computation of the solute concentration distribution, from the literature analysis it is not clear under which conditions the solute concentration can be assumed independent of the entrance length. Usually, it is assumed that the solute concentration is periodic in a repeating cell of the spacer, but it is not yet established under which condition this periodicity may be assumed.

Two flow regimes are of special interest in practical applications of spiral-wound modules. In pressure-driven membrane processes, the Reynolds number, based on the superficial velocity and on the hydraulic diameter, is typically between 300 and 1000. In this range, the velocity field fluctuates mildly with time and some level of chaotic mixing is expected as soon as the solute leaves the concentration boundary layers adjacent to the walls. In this case, and unless the concentration boundary layers are not periodically disturbed, developed mass-transfer condition and constant average Sherwood numbers are expected after a given entrance length, whose value must be quantified in order to assess if entrance effect can be neglected or not in practical applications. In membrane blood oxygenators the channel height is well below 1 mm and the superficial velocity is small, in order to keep the shear stress under acceptable values. Under these conditions the Reynolds number is below 10 and the flow is laminar. It is, therefore, expected that in this particular case the entrance effects should be significant and must be taken into account in the design of membrane modules. The objective of this work is to study the effect of the entrance length on the mass-transfer coefficient in narrow channels filled with different types of spacers.

Mass-transfer coefficients were measured by the limiting current technique, using potassium ferri/ferro-cyanide in a solution with 0.5 M potassium carbonate as supporting electrolyte. The test cell had a narrow rectangular channel, with 2 mm eight and 15 mm with and with a length of 200 mm. Different types of mesh-type spacers were tested that had two layers of cylindrical filaments. The system was simulated by CFD using the open-source OpenFOAM 1.6 package, assuming periodic conditions both in a transverse segment of channel and in a repeating cell of the spacer.

The conditions under which the periodic boundary conditions are valid were identified based on the CFD predictions and a good agreement between the predicted and the experimental Sherwood numbers was obtained in these conditions.

ICEMS Workshop 2011

Abstract #09

Sol-Gel derived Ferroelectric Thin Films for Voltage Tunable Applications

Arne Lüker

ICEMS & Instituto Superior Técnico, Departamento de Física, Av. Rovisco Pais 1, 1049-001 Lisboa

A modified sol-gel method was used to fabricate (Pb0.4Sr0.6)(MnxTi1-x)O3 (Mn doped PST) thin films with x = 0, 0.01, 0.03, and 0.05 on Pt/Ti coated SiO2/Si substrates. The structure, surface morphologies, dielectric and tunable properties of these films were investigated as a function of Mn content (x). X-ray diffraction, scanning electron microscopy and atomic force microscopy analysis showed that all the films were well crystallised with random orientation. It was found that the grain size/roughness, dielectric constant, loss, tunability and figure of merit (FOM) are affected by the Mn doping level. Further on it was found that the ferroelectricity increases with Mn content. The dielectric constant reached a maximum of 1100 and the maximum figure of merit (FOM) was 23.96 with 3 mol% Mn; whereas the maximum value of the tunability was 76.72% at 10 V with 1 mol% Mn.

ICEMS Workshop 2011

Abstract #10

Corrosion sensors for aluminum alloy airframe

P. G. Venancioa, J-C-S- Fernandesb

aDepartamento de Engenharia e Projectos, OGMA, Industria Aeronáutica de Portugal,

2615-173 Alverca, Portugal bICEMS – DEQB, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

Aluminium corrosion of the airframe structure is one of the most important causes for the increasing of maintenance costs of a fleet. In principle, longer inspection intervals could be used as a way to reduce maintenance costs. However, if corrosion is not detected at an early stage, when the removal of the corroded material from the original structure does not involve a structural repair, the costs of a repair may rise significantly. Moreover, based on OGMA experience as a maintenance, repair and overhaul; (MRO) facility, it is known that most of the inspected areas do not have corrosion issues, but nevertheless these inspections incur a high cost to the operator. In order to eliminate the need for inspections in some areas or, at least, in order to increase inspection intervals, the development of a system that could guarantee detection of corrosion in an early stage is essential. By using efficient corrosion sensors, some inspections could be eliminated with a guarantee that a conservative approach could still be used. In this study critical sites of an aircraft, prone to corrosion, have been identified and different corrosion detecting sensors are being developed to be tested in each particular site. Two different types of sensors that are currently being investigated will be discussed in this presentation. One sensor is based on the detection of electrical resistance changes, with the electrode being made of the same material as the structure of the airframe to monitor corrosion. This material is produced in such a way that the rupture of the sensor will indicate corrosion in the corresponding surface of the airframe. The other type of device is an optical sensor that can be used to detect corrosion products inside critical joints that are prone to corrosion. This sensor detects aluminium ions produced in the corrosion process.

ICEMS Workshop 2011

Abstract #11

HDPE/Mesoporous Silica nanocomposites by ‘in-situ’ polymerization

A. Bento1, M. R. Ribeiro1, J. P. Lourenço2, A. Fernandes3, M. L. Cerrada4

1 ICEMS & Departamento Eng. Química e Biológica Instituto Superior Técnico (IST) - Universidade Técnica de Lisboa. Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal

2Centro de Investigação em Química do Algarve (CIQA), Faculdade de Ciências e Tecnologia - Universidade do Algarve. Campus de Gambelas, 8005-139 Faro, Portugal.

3Instituto de Biotecnologia e Bioengenharia (IBB), Departamento Engenharia Química e Biológica, Instituto Superior Técnico (IST DEQB) - Lisboa, Portugal,

4Instituto de Ciencia y Tecnología de Polímeros (CSIC). Juan de la Cierva, 3, 28006, Madrid, España.

Mesoporous materials are interesting candidates to be incorporated as inorganic phase for the preparation of multicomponent polymeric nanocomposites, and the in-situ polymerization has been revealed as promising strategy to be used. In a previous work polyethylene based nanocomposites were prepared by this route, using MCM-41 in a double role: (1) as a carrier for the immobilization of the polymerization catalyst, (2) as inorganic nanofiller of the of the polyethylene matrix formed. [1], [2]

Aiming to enhance the mechanical performance of these materials, several methodologies for preparation of this type of nanocomposites are pursued in this work. These methods intend to increase the interfacial contact and filler dispersion of MCM-41 particles within the PE matrix. The protocols developed involve two main approaches: (1) polymerization of ethylene in the presence of MCM-41 modified with an interfacial agent; (2) copolymerization of ethylene with a polar monomer in presence of non-modified MCM-41, in both approaches the MCM-41 modified or not, may be used either as filler or in a double role of filler and catalyst carrier.

In this way, distinct functionalized MCM-41 materials were synthesized and characterized through FTIR, BET and TGA techniques, in order to assess their morphological features. In this way, a set of nanocomposites, with a given MCM-41 content, was synthesized and characterized from morphological and structural standpoints and the corresponding mechanical parameters evaluated in order to estimate preliminarily the effect of the distinct methodologies and interfacial agents on final properties.

The performance of these materials is discussed in terms of their morphology, namely (filler dispersion, presence of filler aggregates, sample homogeneity) and crystalline structure assessed by SEM, DSC and X-ray Diffraction.

[1] J. M. Campos, J. P. Lourenco, E. Perez, M. L. Cerrada, M. R. Ribeiro, Journal of Nanoscience

and Nanotechnology 2009, 9, 3966-3974. [2] M. L. Cerrada, E. Perez, J. P. Lourenco, J. M. Campos, M. R. Ribeiro, Microporous

Mesoporous Mat. 2010, 130, 215-223.

Acknowledgement: This work was financially supported by Fundação para a Ciência e a Tecnologia (FCT) under the Project PDCT/CTM/66408/2006 and Exchange Collaboration Program CSIC/FCT (projects 2009PT0026 and Proc. 441.000 CSIC 2010/2011, respectively).

ICEMS Workshop 2011

Abstract #12

Optical Properties of Germanosilicate and Germanotellurite Glasses

Gonçalo Monteiro1, Luís F. Santos1, Rui M. Almeida1, Luís Fernandes2, Paulo V. S. Marques2

1ICEMS & Instituto Superior Técnico / TU Lisbon, Av. Rovisco Pais, nº 1, 1049-001 Lisbon, Portugal 2Physics Department U. Porto / INESC PORTO, Rua do Campo Alegre 687 4169-007 Porto, Portugal

In the area of photonics, second harmonic generation (SHG) effect in glass ceramics based on ferroelectric or other highly polarisable phases is of great interest for different non-linear optical applications and opens up new frontiers in optical materials science. High SHG signals are commonly observed in glass ceramics if a crystalline phase with a high SHG efficiency is precipitated from the glass. Crystalline KNbO3 is widely known to have a high second order non-linearity efficiency, being commonly used for frequency doubling of low and medium power solid state lasers, from 914-946nm to blue wavelengths and also in piezoelectric applications.

In this work, new glass compositions in the GeO2–SiO2–Nb2O5–K2O and GeO2–TeO2–Nb2O5–K2O systems were prepared by melt-quenching technique and crystallization of the KNbO3 phase was promoted. Glass density, refractive index and characteristic temperatures have been determined and the glass structure has been analysed by infrared and Raman spectroscopies. The glass compositions were also doped with rare-earths such as erbium, ytterbium and thulium and the Er3+ photoluminescence (PL) at 1.54 m and the corresponding lifetimes were measured and the radiative lifetimes were calculated by Judd-Ofelt analysis. Waveguide fabrication by laser patterning was attempted.

In the germanosilicate and germanotellurite systems a decrease in density and an increase in the characteristic temperatures has been observed with increasing SiO2 content, while the progressive replacement of GeO2 by TeO2 led to a decrease of the characteristic temperatures and a simultaneous increase of their density and refractive index. The structure of these glasses was found to consist of SiO4 (or TeO4 for the germanotellurite compositions) and GeO4 tetrahedral units, together with NbO6 octahedra with some degree of distortion, thus indicating an intermediate character for the niobium oxide.

The germanosilicate glass compositions yielded quantum efficiencies of ~86% and ~58% for the 1% and 2% Er-doped glasses, respectively. A quenching concentration of 6.2x1020 ions/cm3 was obtained, corresponding to ~3.8 mol% ErO1.5. The erbium-doped germanotellurite glasses presented higher FWHM (~60 nm for the 2% ErO1,5 composition) and radiative lifetimes increased with tellurite content, going from ~ 3.3 to 5.2 ms, and 4.2 to 5.8 ms, for 2ErO1,5 and 0.2ErO1,5 compositions, respectively.

Waveguide lines have been produced using a femtosecond laser working at 1044 nm and fiber-guide-fiber insertion losses of 4 dB have been obtained

ICEMS Workshop 2011

Abstract #13

Wear resistant Al-12Si/TiB2 coatings produced by laser cladding

R. Anandkumar, A. Almeida, R. Vilar ICEMS & Department of Chemical and Biological Engineering, Institute of Science and Engineering

of Materials and Surfaces, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal

Composite coatings consisting of an Al-12Si alloy matrix reinforced with TiB2 particles were prepared by laser cladding, from mixtures of Al-12Si alloy and TiB2 powders. The coating’s microstructure is composed of TiB2 particles dispersed in a matrix consisting of proeutectic -Al dendrites and -Al+Si eutectic (figure 1). No chemical reactions between TiB2 and molten Al were observed. The dissolution of TiB2 seems to have been negligible, a result that is compatible with the low solubility product of this compound in molten aluminium and confirms that TiB2 is an excellent reinforcement material for Al-based metal matrix composites. The coatings present a hardness of 156 HV and a wear coefficient of 2.65x10-5 mm3/(Nm) in dry sliding wear tests, with a counterbody of AiSi 440C tool steel. The wear mechanism involves oxidation of asperities, brittle fracture and detachment of the oxide asperities, which are transferred between the sliding surfaces and consolidated into tribolayers in both elements of the tribological pair. The main material removal mechanism is cracking and detachment of brittle tribolayers, which consists predominantly of Fe and Al oxides (figure 2).

Fig 1. Microstructure of the coating; (a) general view; (b) detailed view of the matrix, consisting of -Al

dendrites (A) and -Al+Si eutectic (B).

Fig. 2. Secondary electron SEM micrographs of wear scar surface showing a network of cracks (a) and

craters (b).

ICEMS Workshop 2011

Abstract #14

Design And Assembly Of An Ultrasonic Fatigue Testing Machine

V. Anes, D. Montalvão, A. Ribeiro, L. Reis, M. Freitas

ICEMS &Departamento de Engenharia Mecânica, Instituto Superior Técnico Av. Rovisco Pais, 1049-001 Lisboa, Portugal

mfreitas@dem.ist.utl.pt

The requirements in the design of mechanical components are increasing. The fatigue design standards had changed in the last two decades and a new class of fatigue strength is required nowadays. The endurance limit in the S_N curves beyond the 107 cycles doesn’t correlate the material fatigue strength with the results observed in the field. Therefore, is needed more tests in the range of 107 - 1010 cycles.

These tests made with conventional fatigue machines are expensive and take too long time, thus performing this fatigue tests on a piezoelectric testing system has proven to be an adequate solution.

In this presentation is shown ultrasonic techniques in the design and instrumentations of a piezoelectric testing system Fig. 1, for the fatigue assessment of metallic materials in the very high cycle fatigue (VHCF), under fully reverse loading (R=-1) with 20kHz of working frequency. The machine elements, connectivity’s and functionalities are presented and discussed. The ultrasonic testing system implemented allows to control the test and to measure detailed fatigue data. The machine instrumentation is a novel approach and has proven to be an essential subsystem on this kind of testing machines. SEM investigations shown that the temperature increase or the on/off cooling procedure in the testing process; is correlated with irreversible changes in the material microstructure. Therefore, the instrumentation of this kind of testing machines is of prime importance to validate the fatigue data. This issue is also discussed.

Fig.1 Setup of the Ultrasonic fatigue testing machine implemented.

ICEMS Workshop 2011

Abstract #15

Synthesis and characterization of GaN thin films

S.R. Bhattacharyya

ICEMS & Department of Physics, Instituto Superior Técnico, 1049-001 Lisbon, Portugal

This presentation deals with the synthesis and characterization of GaN in nanocrystalline and polycrystalline thin film form. Nanocrystalline and polycrystalline GaN films were deposited onto fused silica (quartz) and NaCl substrates by radio frequency (R.F.) sputtering of a GaN target (99.999%) in argon plasma at a system pressure of ~ 25 Pa and ~ 0.5 Pa, respectively. p- and n-doped GaN films were deposited by using targets containing 1 at % Be and 1 at % Si in GaN, respectively. The samples were found to be hexagonal in nature, but an increase in cubic phase was observed for depositions at higher temperatures. A host of material characterization techniques, like X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), UV-VIS-NIR spectroscopy, mechanical and electron transport measurements, were undertaken to characterize these films and establish their optical, microstructural, mechanical and electronic behavior.

ICEMS Workshop 2011

Abstract #16

Sub-micron tailoring of bi-soft segment asymmetric polyurethane membrane

surfaces with enhanced hemocompatibility properties

Mónica Faria1, Pedro Brogueira2, Maria Norberta de Pinho1

1 ICEMS & Departamento de Engenharia Química e Biológica, Instituto Superior Técnico, Universidade Técnica

de Lisboa (ICEMS/IST/UTL), Lisbon, Portugal. 2 ICEMS & Departamento de Física, Instituto Superior Técnico, Universidade Técnica de Lisboa

(ICEMS/IST/UTL), Lisbon, Portugal.

Enhancement of membrane hemocompatibility is achieved through the control of the surface

morphology. Bi-soft segment integrally skinned poly (ester urethane urea) (PEUU) membranes

containing polycaprolactone (PCL) as a second soft segment are synthesized with PCL-diol

ranging from 0% – 15% (w/w). Scanning Electron Microscopy and Atomic Force Microscopy

characterized membrane asymmetry and sub-micron roughnesses, Ra, of top dense surfaces as

major assets to development of platelet/membrane surface interactions. Here we show that the

top dense surfaces of asymmetric PEUU membranes can be tailored with different morphologies

when the ratio of the two soft segments PPO/PCL varies. A strong correlation between the top

surface roughnesses, Ra and platelet deposition is identified. The membrane with 15% (w/w) of

PCL-diol, PEUU 85, shows the smoothest top dense layer with a Ra as low as 1 nm which is 5

times below the characteristic value of the PEUU membrane with a single soft segment. The

PEUU 85 asymmetric membrane displayed minimal platelet deposition and inhibition of

extreme stages of platelet activation.

Keywords: integrally skinned asymmetric membranes; surface roughness; hemocompatibility;

platelet adhesion; platelet activation

ICEMS Workshop 2011

Abstract #17

Ferromagnetic Order In Aged Ti1-xCoxO2 Nanoparticles

A. J. Silvestre

ICEMS & Secção Autónoma de Física, Instituto Superior de Engenharia de Lisboa,

R. Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal.

Oxide based diluted magnetic semiconductor (DMS) materials have been a subject of increasing interest due to reports of room temperature ferromagnetism in several systems and their potential use in the development of spintronic devices. However, concerns on the stability of the magnetic properties of different DMS systems have been raised. Their magnetic moment is often unstable, vanishing with a characteristic decay time of weeks or months, which precludes the development of real applications.

This work reports on the ferromagnetic properties of two-year-aged Co-doped TiO2 reduced anatase nanopowders with different Co contents up to 10 at.%. Aged samples retain rather high values of magnetization, remanence and coercivity which provide strong evidence for a quite preserved long-range ferromagnetic order. In what concern Co segregation, some degree of metastability of the diluted Co doped anatase structure could be inferred in the case of the sample with the higher Co content.

Keywords: Co-doped TiO2; preserved ferromagnetic order; DMS; spintronics.

IST Campus Map

Organizing Committee

Augusto Moita de Deus (ICEMS and DEM/IST)

amd@ist.utl.pt

Maria do Rosário Ribeiro (ICEMS and DEQB/IST)

rosario@ist.utl.pt

Reinhard Schwarz (ICEMS and DF/IST)

rschwarz@fisica.ist.utl.pt

Vitor Geraldes (ICEMS and DEQB/IST)

vitor.geraldes@ist.utl.pt

Acknowledgements

The Organizing Committee would like to acknowledge the assistance of several ICEMS

members, collaborators and staff, namely:

Isabel Nogueira

João Campos

Marisa Pereira

Patrícia Almeida Carvalho