8º EncuentroFranco-Español deQuímica y Físicadel Estado Sólido

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FROM IMPLANTS TO REGENERATIVE MEDICINE María Vallet Regí

Dpto. Química Inorgánica y Bioinorgánica. Universidad Complutense de Madrid. Instituto de Investigación Sanitaria Hospital 12 de Octubre i+12. Madrid, Spain Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-

BBN), Madrid, Spain vallet@ucm.es

The use of biomaterials in patients requiring repair or regenerate parts of their body is a subject of great interest because of the solutions that can provide for a better quality of life. However, technical issues and biological materials or cells are remarkable and, before applying those biomaterials to patients, preclinical models should be analyzed to solve the limitations of cell viability, mechanical strength (from the moment they are introduced into the body until they are replaced by new tissue), and also the biological adaptation in the organism. The manufacture of spare parts for the human body, by traditional methods or using tissue engineering or cell therapy, are currently challenges are of great importance in biomedical research. In this talk those ideas will be properly addressed.

Bioceramics with clinical applications.Edited by M.Vallet-Regí John Wiley and Sons Ltd. United Kingdon. 2014 Biomedical applications of mesoporous ceramics: drug delivery, smart materials and bone tissue engineering.Edited by M.Vallet-Regí, M. Manzano, M. Colilla. CRC Press. 2013. I. Izquierdo, A.J. Salinas, M. Vallet-Regí. Int. J. Appl. Glass Sci.. 4, 149-161 2013 S. Sánchez-Salcedo, M. Colilla, I. Izquierdo and M. Vallet-Regí J. Mater. Chem. B, 1, 1595-1606 2013. M. Colilla, B. González, M. Vallet-Regí. Biomater. Sci. 1, 114–134 2013 A. Salinas, P. Esbrit, M. Vallet-Regí. Biomater. Sci. 1, 40-51 2013. D. Arcos, M. Vallet-Regí. Acta Materialia. 61, 890-911 2013. J. Simchenn, A. Baeza, D. Ruiz, M. Esplandiu, M. Vallet-Regí.. Small. 8(13), 2053-2059 2012. M. Vallet-Regí, International Scholarly Research Network ISRN Materials Science, Volume 2012, Article ID 608548, 20 pages, doi:10.5402/2012/608548 A. Baeza, E. Guisasola, E. Ruiz-Hernández and M. Vallet-Regí. Chem. Mater. 24, 517-524 2012. M. Manzano, M. Vallet-Regí. Prog. Solid State Ch. 40, 17-30 2012. A. Baeza, E. Guisasola, E. Ruiz-Hernández and M. Vallet-Regí. Chem. Mater. 24, 517-524 2012. M Vallet-Regí and E. Ruiz-Hernández. Adv. Mater. 23, 5177–5218. 2011 M. Vallet-Regí, M. Colilla and B. González. Chem. Soc. Rev. 70, 596-607 2011 E. Ruiz-Hernández, A. Baeza, M. Vallet-Regí. ACS Nano. 5 (2), 1259–1266 2011. M. Vallet-Regí, E. Ruiz-Hernández, B. González, A. Baeza J. Biomater. Tissue. Eng. 1, 6-29 2011.

Materials Science and the development of industrial applications, latest examples related to Rare Earths

P. MAESTRO1,* T. LE-MERCIER2,*, V. BUISSETTE2,*

1 SOLVAY, Scientific Director, 178 Ave Albert Schweitzer, 33600, Pessac, France 2 SOLVAY, Centre de Recherches, 52 Rue de la Haie-Coq, 93308, Aubervilliers, France

* Corresponding author: patrick.maestro@solvay.com

Rare earths industry is strongly dependent on its capacity to develop innovative applications based on the very specific physical properties these elements exhibit, but also on the differentiation that synthesis can bring, through the control of morphology, or reactivity of the products. As a matter of fact, solid state chemistry has played a key role in inventing new phases capable of delivering specific physical and chemical properties, like in luminescent materials catalysts systems, magnets, etc.. But in addition to the relationship between structure and property, real applications often depend on the capacity of the product to deliver performance through the mastering, through the synthesis capabilities, and the control of particle size, phases distribution, surface reactivity, … Examples will be given on how we have taken into account the importance of coupling structural aspects to materials science and inorganic synthesis, for the development of, for example, new phosphors with low terbium content, or new powders for fine polishing, by combining benchmark synthesis capabilities and thorough understanding of the mechanisms relating the composition of the products and its performance

Investigation of thermopower in transition metal oxides

and related sulfides and selenides

Sylvie Hébert

Laboratoire CRISMAT, UMR6508 CNRS et ENSICAEN, 6 Bd du Maréchal Juin 14050 CAEN Cedex, France *sylvie.hebert@ensicaen.fr

The Seebeck coefficient is a powerful probe of the electronic properties of a material as it is very sensitive to the nature of carriers, to the band structure of the materials and to the different diffusion processes and transport mechanisms. It can also be very sensitive to the presence of electronic correlations, as for example in oxides [1]. Moreover, the Seebeck effect can be used to generate electricity from waste heat, and has been more and more investigated in the recent years with the aim of finding new efficient thermoelectric materials. In this talk, I will show results we have obtained in oxides with different crystallographic structures, with corner shared octahedra (perovskites) or edge shared octahedra (misfits and hollandites), to show the peculiarities of Seebeck coefficient observed for each structure, and emphasize the role of spin and orbital degeneracies associated to the transition metal cation (Co, Ru…) on thermopower [2]. For thermoelectric applications, the three important quantities to optimize are the Seebeck coefficient S, the electrical resistivity ρ and the thermal conductivity κ, and the ZT value (ZT = S2T/(ρκ)) shoud be close to 1. Even if some ZT close to 1 have already been reported, the best ZT are close to 0.4 – 0.5 at ~ 1000K for oxides, and the major limiting factor is the too large electrical resistivity. By increasing covalency, better conductivities are obtained in sulfides and selenides [3] and we will show that for similar structures with edge shared octahedra, sulfides and selenides can also present interesting thermoelectric properties [4].

Referencias [1] J. Merino et al., PRB61, 7996 (2000) ; K. Behnia et al., JPMC16, 5187 (2004). [2] S. Hébert et al., PSSA210, 69 (2013). [3] K. Koumoto et al., J. American Ceramic Soc. 96, 1 (2013). [4] H. Takahashi et al., Chem. Mater. 25, 1809 (2013).

 

Cartography  of  the  Van  der  Waals  Territory  

Santiago  Alvarez  Departament  de  Química  Inorgànica  and  Institut  de  Química  Teòrica  i  Computacional  

Universitat  de  Barcelona,  Martí  i  Franquès  1-­‐11,  08028  Barcelona  

   

A  cartography  of  the  intermolecular  distance  region  between  two  elements  provides  a  perspective  view  of  the  bonding  –  non  bonding  duality,  and  allowed  to  extract  a  new  consistent  set  of  van  der  Waals  radii  for  most  naturally  occuring  elements.    For  the  case  of  transition  metal  centers  with  loosely  bound  ligands  and  ill-­‐defined   coordination   spheres   that   populate   the   lawless   frontiers   between   bonds   and   van   der   Waals  contacts,  a  contiuous  shape  measures  approach  allows  us   to  tackle   the  problem  of  precisely  defining  the  stereochemistry   of   the   coordination   sphere.     Finally,   coordination   ability   indices   for   solvents   and   anions  towards   transition   metals   or   lanthanides   have   been   deduced   based   on   the   frequency   with   which   they  appear  as  coordinated,  semicoordinated  or  uncoordinated  species  in  crystal  structures.  

 

References  

S.  Alvarez.    "A  Cartography  of  the  Van  der  Waals  Territory",  Dalton  Trans.  2013,  42,  8617.  

A.   Ruiz-­‐Martínez   et   al.     "Ligand   Association/Dissociation   Paths   and   Ill   Defined   Coordination   Numbers",  Chem.  Eur.  J.  2010,  16,  6567.  

R.   Díaz-­‐Torres,   S.   Alvarez.     "Coordinating   Ability   of   Anions   and   Solvents   Towards   Transition  Metals   and  Lanthanides",  Dalton  Trans.  2011,  40,  10742.  

 

 

Persistent luminescence of the ZnGa2O4:Cr nanophosphors for in-vivo bio-imaging

Bruno Viana

Institut de Recherche de Chimie Paris, CNRS

Chimie ParisTech, 11 rue Pierre et Marie Curie, 75005 Paris, France

Abstract :

ZnGa2O4 (ZGO) is a normal spinel. When doped with Cr3+ ions, ZGO:Cr becomes a high brightness persistent luminescence material with an emission spectrum perfectly matching the transparency window of living tissues. It allows in vivo mouse imaging with a better signal to background ratio than classical fluorescent near infrared probes. One of the most interesting characteristic of ZGO:Cr lies in the fact that its persistent luminescence can be excited with orange/red light, well below its band gap energy and well in the transparency window of living tissues. A mechanism based on the trapping of carriers localized around a special type of Cr3+ ions can explain this singularity. Optical imaging of vascularization, tumors and grafted cells can therefore be realized.    

Mª  Pilar  Alonso  Abad       VIII  Encuentro  franco-­‐español  de  Qca.  y  Fca.  del  estado  sólido    Universidad  de  Burgos     2-­‐4-­‐Abril-­‐2014  

El  Patrimonio  vidriero  del  Real  Monasterio  de  Las  Huelgas  de  Burgos:    Patrimonio,  Conservación  y  Caracterización  

1    

EL PATRIMONIO VIDRIERO DEL REAL MONASTERIO DE LAS

HUELGAS DE BURGOS:

PATRIMONIO, CONSERVACIÒN Y CARACTERIZACIÓN Mª Pilar Alonso Abad

Universidad de Burgos

Resumen

La vidriera es un arte del fuego muy versátil, simbólico y doctrinal. En la Historia ha

disfrutado de momentos de mayor y menor desarrollo en los que se ha podido descubrir la

riqueza productiva y la constante experimentación en sus materiales y composición.

Fue precisamente durante la Edad Media cuando alcanzó su mayor apogeo,

particularmente en Europa. Las catedrales asumieron el protagonismo de importantes programas

vidrieros que complementaron la iconografía presentada en el edificio pero, junto a ellas, fueron

determinantes algunos monasterios –más bien algunas órdenes religiosas-, particularmente los

vinculados de algún modo a la monarquía y/o la nobleza, porque bajo su amparo, protección y

promoción llevaron a cabo notables representaciones de este arte. De este modo, los reyes,

obispos y abades, fueron los grandes impulsores de los programas vidrieros.

El Real Monasterio de Santa María la Real de Las Huelgas de Burgos atesora un

importante exponente de vidrieras, las más antiguas conservadas de la Península. Gracias al

patrocinio regio, esta institución, real y religiosa, recibió este arte del fuego en un momento en

que se debatía su utilización en el seno de la Orden cisterciense, y en la Península se desconocía

la técnica y el procedimiento de elaboración de la vidriera, cuya historia había abierto una de

sus páginas más importantes a finales del siglo XII y que perduraría durante siglos.

Hábiles y diestros artesanos franceses realizaron un ciclo del apostolado para la iglesia

monástica. Retirado de este lugar, se ha conservado parcialmente y disperso –en la Sala

Capitular, en la Hospedería y en el Nuevo Oratorio de la comunidad-.

En el año 2008 culminó el proceso de restauración integral de las tres vidrieras que

cierran los ventanales del Capítulo del Claustro de San Fernando de esta abadía burgalesa. Un

vidrio rojo, de características peculiares, extraído durante el proceso de conservación-

restauración de una de las vidrieras, fue analizado en el Instituto de Cerámica y Vidrio del CSIC

para conocer su composición química y su estructura, pudiendo reconocer una composición

multicapa característica de la Edad Media.

Mª  Pilar  Alonso  Abad       VIII  Encuentro  franco-­‐español  de  Qca.  y  Fca.  del  estado  sólido    Universidad  de  Burgos     2-­‐4-­‐Abril-­‐2014  

El  Patrimonio  vidriero  del  Real  Monasterio  de  Las  Huelgas  de  Burgos:    Patrimonio,  Conservación  y  Caracterización  

2    

Bibliografía

ALONSO ABAD, Mª Pilar, “Las vidrieras del Real Monasterio de Las Huelgas de Burgos.

Pasado y Presente”, Estudios de Historia y Arte. Homenaje al Profesor D. Alberto C. Ibáñez

Pérez, Universidad de Burgos, 2005, pp.253-257.

ALONSO ABAD, Mª Pilar, CAPEL DEL ÁGUILA, Francisco, et alii, Las vidrieras del

Rosetón del Sarmental de la Catedral de Burgos: Caracterización físico-química de algunos

vidrios, XLVIII Congreso Nacional de la Sociedad Española de Cerámica y Vidrio. SECV,

Oviedo, 29-31-Octubre-2008.

ALONSO ABAD, Mª Pilar, CAPEL DEL ÁGUILA, Francisco, et alii, “Caracterización de un

vidrio rojo medieval procedente de las vidrieras del Monasterio de Las Huelgas de Burgos”,

Boletín de la Sociedad Estatal de Cerámica y Vidrio, vol.48, nº4 (2009/Julio-Agosto), p.179-

186.

LA IGLESIA, A.; LÓPEZ DE AZCONA, M.C., “El Tratado del secreto de pintar a fuego las

vidrieras de colores de F. Sánchez Martínez, 1718”, Boletín de la Sociedad Española de

Cerámica y Vidrio, vol.33 (1994), p.327-331.

L’ESCALOPIER, Charles,Comte, Théophile prètre et moine, Essai sur divers arts=Theophili

presbyteri et monachi Libri III seu Diversarum artium schedula, Paris, 1873.

NIETO ALCAIDE, Víctor, La vidriera y su evolución, Madrid, 1974.

NIETO ALCAIDE, Víctor., La vidriera española. Ocho siglos de luz, Madrid, 1998.

 

VIII Encuentro Franco-Español de Química y Física de Estado Sólido 2-4 Abril 2014, Vila-real Laser synthesis of coatings under extreme conditions I. de Franciscoa, V. V. Lennikova, F. Rey-Garcíaa,b , C. Baob, L. A Angurela, G. F. de la Fuentea* aICMA (CSIC-Universidad de Zaragoza), c/María de Luna, 3 50018 Zaragoza bUA de Microóptica & Óptica GRIN (USC-CSIC), Facultade de Óptica e Optometría, Campus Sur, Universidade de Santiago de Compostela, Campus Vida s/n 15782. Lasers have become useful tools in a large number of industrial processes during the last decades and offer unprecedented potential to advance materials processing under conditions never before available in the laboratory. This is particularly attractive when considering high melting solids and their interaction at extremely high temperatures. Since laser beams may be easily steered within complex geometrical arrangements, they are ideal sources to achieve high temperatures in any type of environment. For example, they enable high temperature treatments in open air, within vacuum, under various gas streams and, as recently demonstrated, within high temperature kilns [1, 2]. In essence, their potential to develop new, high temperature chemistry, is only limited by our imagination. A new “Laser Furnace” tool that enables processing of inorganic solids under continuous displacement, within an externally heated volume, will be presented along with its main features. One of the main advantages of this recently patented method is that it allows reaching extremely high temperatures on coated surfaces, without causing appreciable thermal-stress derived damage on the substrates. Examples of its application to structural and functional materials will be presented and discussed. 1.  L.  C.  Estepa  &  G.  F.  de  la  Fuente,  Patent  No.  200600560  (2006).  2.  I.  de  Francisco  et  al.,  Solid State Sciences 13 (2011) 1813-1819. Acknowledgements:  MAT2010-­‐18519,EU:  LIFE11/ES/560  &  UV-­‐MARKING  (FP7),  DGA-­‐T87.  

Advanced Applications using an annular four-channel Silicon Drift Detector

R. Terborg, A. Kaeppel, T. Salge

Bruker Nano GmbH, Schwarzschildstr. 12, 12489 Berlin, Germany

Silicon Drift Detectors (SDDs) have become the standard detectors for energy dispersive x-ray

detection in the last few years. High resolution type SDDs have an energy resolution down to

121eV or better at Mn-Ka. They also have a good low-energy performance down to energies

about 69 eV (Al-Ll/Ln) and show undistorted Gaussian peak shapes in the low-energy range. Optimized electronics maintain the energy resolution even for count rates up to 100 kcps input

count rate.

A special configuration has recently been developed for certain applications in order to improve

certain limitations: Multiple element SDDs with four separate detectors integrated onto one chip

but with separate electronics, provide even higher count rates through increased active area

without increasing pile-up or dead time [1,2].

A special multi element concept is the XFlash® 5060FQ (Fig. 1), an annular detector which can

be placed between the pole piece and the sample in a standard SEM using a BSE detector like

setup. The four SDD elements have an active area of 15mm² each resulting in a total of 60mm².

This large active area and the annular geometry, where the detector elements are very close to the

x-ray source, lead to an extremely large solid angle of more than 1 sr. This is a value which is

typically 100 times larger than a 10mm² detectors in a conventional setup. Therefore extremely

high count rates can be achieved easily even with low probe currents, and can be processed with

four separate electronic channels in parallel, leading to maximum output count rate of more than

1,100,000 cps. The energy resolution is 133eV or better at Mn-Ka.

These properties make the detector an ideal device for high speed mapping applications. Fig. 2

shows a high speed x-ray mapping of a micro crator in an aluminium foil, produced by a small

projectile consisting of magnesium, calcium and iron. The distribution of these elements was

analysed in a mapping acquired at 12kV accelerating voltage with a probe current of 2nA. The

element mapping with a resolution of 4096x3072 pixels was taken in only 210s total acquisition

time. The count rate was 1.4cps resulting an average number of counts of 11 per pixel. The ability

of this detector to acquire X-rays from four different directions due to the four channels and a

relatively high take-off angle lead to a significant reduction of shadowing effects. Therefore also

the element distribution at the bottom of the crater can be seen which would not be possible with

a conventional detector setup.

References

[1] H. Soltau et al., Microsc. Microanal. 15 (Suppl.2) (2009), 204

[2] R. Terborg, M. Rohde, Microsc. Microanal. 17 (Suppl.2) (2011), 892

Fig. 1. Flat Quad detector (XFlash® 5060FQ), which is placed between the pole piece and

the sample.

Fig. 2. Ultra high speed mapping of a micro crater in an aluminium foil. HV=12kV, I=2nA,

resolution: 4096x3072 pixel, acquisition time 210s, average count rate 1.4 Mcps. Note the

reduced shadow effects.

Electrodeposition of oxide thin films and nanostructures for optoelectronics

Daniel LINCOT, Jean ROUSSET, Fabien TSIN, Aurelien DUCHATELET, Tarik SIDALI, Elisabeth CHASSAING

Institut Photovoltaïque Ile de France (IPVF), Institut de Recherche et Dèveloppement sur l'Energie Photovoltaïque,,UMR CNRS-EDF-Chimie Paristech, 6 Quai Watier, 78401 Chatou

1. Introduction

The electrodeposition of oxide thin films and nanostrucures is an emerging field with great interest both for the fundamental aspects at the frontier between electrodeposition and materials and for optoelectronic applications. This presentation will recall the grounds of the electrodeposition of oxides and move to specific cases which are under study in our laboratory. The first one concerns zinc oxide, with three areas, the deposition of thin films, that of nanocolumns and that of nanoporous films by templated growth. The specificity of electrodeposition of zinc oxide is that it possesses already after fabication, semiconductor properties with excellent structural quality. It is also possible to control its conductivity thanks to the introduction of extrinsic dopants like chlorine. This approach is emerging as a potential candidate to produce transparent conducting oxides in photovoltaics, with exemples for CIGS thin film solar cells. In the case of nanostructures, we will present some applications in the field of dye sensitized solar cells (DSSC) and highly specific topics as electrical properties of nanoporous networks. An other exemple of remarkable as grown properties will be given by results obtained on the electrodeposition of copper oxide. The last topic which will be presented concerns the electrodeposition of multinary Cu-In-Ga oxides/hydroxides. These films of controlled composition can serve as intermediates for the formation of copper indium gallium diselenide layers for efficient solar cells.

Chemistry and applications of perovskite oxynitrides Amparo Fuertes

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain) E-mail: amparo.fuertes@icmab.es

Oxynitrides represent a vast group of compounds to explore new materials with properties analogous to oxides. [1] The similarities in electronegativity, polarizability, ionic radii and coordination numbers of nitrogen and oxygen allow the formation of the same structural types when combined with cations, as well as the mutual substitution of both anions at the same crystallographic sites. This may result in the formation of solid solutions where the formal oxidation state of one or more cations changes according to the O/N ratio. Oxynitride perovskites have been recently reported as non-toxic inorganic pigments, dielectric materials, visible light-active photocatalysts and colossal magnetoresistance materials among other applications. [2] Perovskites of alkaline earth and early transition metals with formula AMO2N (A= Sr, Ba) have been reported as dielectric materials (M=Ta) and visible light-active photocatalysts for water splitting (M=Nb, Ta). Perovskites of europium and Nb, Ta or W show a variety of electrical and magnetic properties that are tuned by the valence states of the cations and adjusted by the N/O ratio. They are prepared by treating precursor oxides under NH3(g) and the nitrogen stoichiometry is controlled by changing the temperature, flow rate and treatment time in the ammonolysis reaction. Depending on the electronic configurations of europium and the transition metal these compounds may show electronic conductivity and ferromagnetism that if coupled result in giant to colossal magnetoresistance. [3,4] Moreover microstructural inhomogeneities lead to non-intrinsic magnetocapacitance and non-ohmic conductivity. [5] The differences in electrical charge and electronegativity between nitrogen and oxygen direct the ordering of both anions in many oxynitrides. [6] In the above perovskites the ordering is driven by covalency and this lead to a preferred cis configuration of nitride anions in the octahedra MO4N2 and the formation of disordered zig-zag M-N chains. [7] The anion order remains at high temperature in the pseudocubic phase and directs the rotations of the octahedra in the room-temperature superstructure. This lecture will present recent results on perovskite oxynitrides of europium, strontium and the early transition metals Ta, Nb, W and V, [8] focussing on the relationships between the synthesis conditions, the oxidation states of the cations, the crystal symmetries and tilt transitions, the anion ordering and the physical properties.

References [1] A.Fuertes, Dalton Trans. 2010, 39, 5942. [2] A.Fuertes, J. Mat. Chem. 2012, 22, 3293. [3] A.B.Jorge, J.Oró-Solé, A.M.Bea, N.Mufti, T.T.Palstra, J.A.Rodgers, J.P.Attfield and A.Fuertes, J. Am.

Chem. Soc. 2008, 130, 12572. [4] M. Yang, J.Oró-Solé, A. Kusmartseva, A.Fuertes, and J. P.Attfield, J. Am. Chem. Soc. 2010, 132, 4822. [5] A. Kusmartseva, M. Yang, J. Oró-Solé, A. M. Bea , A. Fuertes and J. P. Attfield , Appl. Phys. Lett., 2009, 95,

022110. [6] A.Fuertes, Inorg. Chem., 2006, 45, 9640-9642. [7] M.Yang, J.Oró-Solé, J.A. Rodgers, A. B. Jorge, A.Fuertes, and J. P.Attfield, Nature Chem. 2011, 3, 47-52. [8] J. Oró Solé, L. Clark, N. Kumar, W Bonin, A. Sundaresan, J.P. Attfield, CNR Rao and A. Fuertes, J. Mat.

Chem. C, 2014, DOI:10.1039/C3TC32362E.

Comunicación Oral

Sólidos mullíticos preparados a partir de geles y vidrios

Noemí Montoya, Pablo Pardo, José Miguel Calatayud, Hadiseh Tabaie y Javier Alarcón

Universidad de Valencia, Departamento de Química Inorgánica, Calle Doctor Moliner 50, 46100-Burjasot (Valencia) España

javier.alarcon@uv.es

1. Introducción La mullita es un componente esencial de muchos materiales cerámicos tradicionales de amplio uso doméstico e industrial, incluyendo desde los productos de la denominada Cerámica Blanca hasta productos de porcelana eléctrica con alta resistencia mecánica, y también de cerámicos técnicas, tales como los productos monofásicos de mullita con alta resistencia mecánica a temperaturas muy elevadas. La mullita es el único compuesto binario dentro del sistema SiO2-Al2O3. Estructuralmente es una disolución sólida con estequiometría Al4+2xSi2-2xO10-x, siendo estables termodinámicamente en el intervalo composicional 0,25 ≤ x ≤ 0,4 [1, 2]. No obstante, se han detectado mullitas metaestables, de diferentes procedencias, hasta con contenidos de 85 % en peso de Al2O3 (x>0,64). En esta comunicación vamos a mostrar como mediante la utilización de un método no convencional simple de preparación de sólidos inorgánicos no metálicos (cerámicos), tal como el sol-gel, se pueden obtener mullitas en todo el intervalo de composiciones incluyendo las composiciones metaestables muy aluminosas [3]. Estas mullitas se han caracterizado por diferentes técnicas, incluyendo difracción de rayos X, espectroscopias IR, Raman y resonancia magnetica nuclear y por microscopia electrónica de barrido y transmisión. Los resultados confirman que mediante esta técnica se pueden preparar mullitas con relaciones Al2O3:SiO2 mayores de 7,3:2, es decir con contenidos mayores de alumina de 85 % (en peso). Con el objetivo de mostrar nuevas aplicaciones de solidos basados en la fase mullita, en la segunda parte de la comunicación comentaremos algunos pasos en el desarrollo de productos cerámicos por excelencia, concretamente de esmaltes vitrocerámicos basados en fase cristalina mullita [4]. Estos se desarrollaron a partir de vidrios en el sistema cuaternario CaO-MgO-Al2O3-SiO2 adicionando los aditivos requeridos para permitir la cristalización controlada en el intervalo de temperaturas entre 1100 y 1200 ºC [5]. La cantidad de mullita desarrollada en estos esmaltes vitrocerámicos tratados en proceso rápido a 1160 ºC es de 19,5 % en peso y su microestructura muestra cristales de mullita aciculares bien formados dispersos en la fase vítrea residual. Los resultados de las propiedades mecánicas de estos esmaltes vitrocerámicos desarrollados industrialmente fueron prometedores. No obstante todavía deben realizarse esfuerzos dirigidos a optimizar el tamaño de la fase cristalina desarrollada en el esmalte, en cuanto a conseguir esmaltes vitrocerámicos nanofásicos.

Agradecimientos Se agradece la financiación del Ministerio de Ciencia y Tecnologia por la financiación al proyecto

Consolider Ingenio (CSD2010-00065) y al proyecto Prometeo (2011/008) de la Generalitat Valenciana. Asimismo, agradecemos a los investigadores F. J. Torres y a E. Ruiz de Sola su contribución a los resultados presentados.

Referencias [1] W. E. Cameron, “Compositions and cell dimensions of mullite”, Am. Ceram. Soc. Bull. 56, 11, (1977), 1003-

1011. [2] H. Schneider, R. X. Fischer, D. Voll, “Mullite with lattice constants a>b”, J. Am. Ceram. Soc., 76, 7, (1993),

1879-1881. [3] E. Ruiz de Sola, F. Estevan, F. J. Torres, J. Alarcón, “Effect of termal treatment on the structural evolution of

3:2 and 2:1 mullite monophasic gels”, J. Non-Cryst. Solids., 351,(2005), 1202-1209. [4] R. Casasola, J. Ma. Rincón, M. Romero “Glass-ceramic glazes for ceramic tiles: a review”, J. Mater. Sci., 47,

2, (2012), 553-582. [5] F. J. Torres, E. Ruiz de Sola, J. Alarcón, “Effect of boron oxide on the microstructure of mullite-based glass-

ceramic glazes for floor-tiles in the CaO-MgO-Al2O3-SiO2 system”, J. Eur. Ceram. Soc., 26, (2006), 2285-2292.

Solid State Chemistry of some Chromium Oxides

Miguel Ángel Alario y Franco Laboratorio Complutense de Altas Presiones. Facultad de Química. Universidad Complutense. 28040 Madrid. SPAIN (EU). e-mail: maaf@quim.ucm.es; http://www.ucm.es/info/labcoap/index.htm

As most transition metals, chromium exhibits several oxidation states, which, in the case of oxide materials, are limited to Cr (II to VI). This, combined with their comparative stability implies the relative scarcity of binary, single-valent oxides, which essentially are Cr2O3 and CrO3. Using HP & HT in the synthesis, one can obtain the, also important, CrO2. Nevertheless, considering mixed–valent oxides the list increases to Cr2O5 (which is, in fact, Cr3+

2Cr6+4O15), Cr5O12 (that is formulated as CrIII

2CrVI3O12) and Cr3O8 which is, in fact Cr8O21

(formulated as CrIII2(CrVI O4)2(CrVI

4O13) and to the short list of CS phases (CrnO2n-p) observed between CrO2 and Cr2O3.

However, one can largely extend the checklist by making ternary or higher oxides by the combination of the above species with different oxides of both transition and non-transition metals.

In the present lecture, we will describe a series of multinary oxides of Chromium that we have obtained by solid state reactions at High Temperature and, often, with the concourse of High Pressure. By this means, and starting with CrO2, we have prepared a number of perovskite, rutile and hollandite based multinary oxides such as: Sr1-xCaxCrO3 (0 < x < 1), “PbCrO3”, Sr3Cr2O7, MSr2RECu2O7 (M <> Ru, Cr, Ir, Mo; RE <> Rare Earth) and some misfit layer compounds around the [SrO2][CrO2]1.85 composition; we will also briefly mention K1.2Cr8O16 and the Cr1-xVxO2 solid solution.

All these materials show remarkable microstructures (as observed by HREM & ED) and very interesting transport and magnetic properties.

We have also used EEL-Spectroscopy, performed in situ in the electron microscope, to establish the oxidation states of chromium in the different oxides.

After a brief general description of the ensemble, we will discuss, in order of complexity, some of them. This will show inter alia the change in the microstructure with composition in the solid solutions, the remarkable structural complexity of “PbCrO3” as well as some intriguing and unusual dependence of the synthesis conditions for the MSr2RECu2O7 (M <> Ru, Cr, Ir, Mo) family on the Rare Earth element.

Acknowledgements: I would like to thank my past and present doctoral students: A. Dos Santos, E. Castillo ,

Á. Arévalo, R. Ruiz. I. Pirrotta & Sourav Marik, for his important contributions to this work and Dr. J.M. Gallardo for technical assistance. I would also like to thank Dr. A. Durán (UNAM-Mexico) and Professors E. Morán and R. Sáez (both at UCM-Madrid. Spain) for valuable comments.

References: M.Á. Alario & K. S.W. Sing: J. Thermal Analysis (1972) E. Castillo-Martínez, A. M. Arévalo-López, R. Ruiz-Bustos, and M. A. Alario-Franco: Inorganic Chemistry, Vol. 47, No. 19, 2008. Ángel M. Arévalo-López, Miguel Á . Alario-Franco:

Journal of Solid State Chemistry 180 (2007)

3271–3279. Ángel M. Arévalo-López, Miguel Á . Alario-Franco:Inorg. Chem. 2009, 48, 11843–11846. Pirrotta, J. Fernández-Sanjulián, E. Morán, M. A. Alario-Franco, E. Gonzalo, A. Kuhn and F. García-Alvarado: Dalton Trans., 2012, 41, 1840. Sourav Marik, A J Dos santos-Garcia, Emilio Morán, O Toulemonde and M A Alario-Franco: J. Phys.: Condens. Matter 25 (2013) 165704.

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ABSTRACT BOOK

Figure 1. SEM of SrMnO3.0 particles The inset shows the particle

size distribution.

Direct atomic observation of Sr-Mn-O nanoparticles Irma N. González-Jiménez1, *, Almudena Torres-Pardo1, 2, Ana E. Sánchez-Peláez1, Ángel

Gutiérrez1, David Portehault3, Clément Sanchez3, Mar García-Hernández4, José M. González-Calbet1, 5, Marina Parras1 and Áurea Varela1.

1. Departamento de Química Inorgánica, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid (SPAIN).

2. CEI Campus Moncloa, UCM-UPM, Madrid, (SPAIN). 3. Chimie de la Matière Condensée de Paris, Collège de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05

(FRANCE). 4. Instituto de Ciencia de Materiales, CSIC, Cantoblanco, 28049 Madrid (SPAIN).

5. Centro Nacional de Microscopía Electrónica CNME, 28040 Madrid (SPAIN). *irmagj@quim.ucm.es

The current demand of technological devices requires the continuous preparation of new compounds at the nanometer scale in such a way that their chemical and physical properties enable the development of novel applications. Mn-related mixed nanooxides constitute a promising system in the field of nanoscience and nanotechnology as a result of the structural variety, due to the number of oxidation states in which Mn can be stabilized, and outstanding properties found in their bulk counterparts [1]. Particularly, in the Sr-Mn system there are several well-known phases as SrMnO3, Sr2Mn2O5, Sr4Mn3O10, etc. However, none of them has been prepared in the form of nanoparticles up to now. The electrical and magnetic properties manifested in these materials, gain much more relevance in those structural types which can accept anion deficiency. We report for the first time the stabilization and structural and magnetic characterization of single crystalline 4H-SrMnO3- δ (δ=0, 0.18) nanoparticles and Sr4Mn3O10 nanoplatelets. SrMnO3. Stoichiometric 4H-SrMnO3.0 nanoparticles have been successfully synthesized from thermal decomposition, at 850 ºC under oxygen gas flowing atmosphere, of a new heterometallic precursor [SrMn(edta)(H2O)5]·3/2H2O which crystal structure has been solved by single crystal X-ray diffraction. From this precursor, highly homogeneous 4H-SrMnO3.0 nanoparticles with average particle size 70 nm are obtained (figure 1). Local structural information, provided by atomically-resolved microscopy techniques, shows that 4H-SrMnO3.0 nanoparticles exhibit the same general structural features than the bulk material, although structural disorder, due to edge-dislocations, is observed. The nanosize of particles enables a topotactic reduction process at 220 ºC stabilizing a metastable 4H-SrMnO2.82 phase while a cubic related phase is always stabilized for anionic compositions below SrMnO2.98 in bulk material [2]. This anionic deficiency is accommodated via insertion of cubic layers in hexagonal perovskites. In our case and as a result of breaking the 4H-sequence (…hchc…), extended defects are generated. These can be observed and assessed providing the most refined spatial resolution imaging and spectroscopic techniques. With these techniques the topotactic reduction pathway can be followed step by step at an atomic level (figure 2). Magnetic characterization of nano-SrMnO3.0 shows significant variations with respect to the bulk material. Besides the dominant AFM interactions, a weak FM contribution as well as exchange bias and a glassy-like component are present. After the reduction process, the stabilization of Mn3+ in the

4H-structure gives rise to magnetic anomalies in the 40-60 K temperature range. Sr4Mn3O10. Sr4Mn3O10 nanoplatelets have been prepared by molten salts method at 600 ºC under argon gas flowing atmosphere. Sr(OH)2 is used in high excess as both solvent and reactant. The reactant excess is removed by adding HNO3 (cc). This washing step affects the particles in such a way that amorphous areas appear in all nanoplatelets (figure 3a, b). The growth mechanism for Sr4Mn3O10 particles was followed by recording low magnification HRTEM images of particles obtained at different synthesis time. Hexagonal-shaped flat morphology was observed for smallest size particles formed after short reaction time. These particles seem to aggregate each other along the [1 1 0] crystallographic direction to form bigger particles (figure 3c, d) and additionally, these medium size particles also seem to stack on top of each other (figure 3e) giving rise to the thicker and biggest particles similar to those observed after longer reaction time. Magnetic properties of Sr4Mn3O10 platelets will be discussed.

Figure 2. (a) Atomically-resolved HAADF image corresponding to a defect area of a SrMnO2.82 nanoparticle along [010]. Extended structural defects (yellow box) are involved on the rearrangement of the stacking sequence of hexagonal and cubic layers along a-axis (marked as A and B areas). Red and green dots indicate Sr and Mn atomic columns, respectively. (b) Schematic drawing of the cationic rearrangement along a-axis (color code: Sr in red; Mn in green; O positions in blue). (c,d) Simultaneously recorded high magnification [010] HAADF and ABF images, respectively, showing the detailed structure in the defect area. A cubic layer is schematically represented: red, green and blue dots indicate Sr, Mn and O positions, respectively. Yellow arrow indicates Mn-O-Mn rows.

Figure 3. Low magnification HRTEM image of (a) a representative Sr4Mn3O10 particle obtained after 1 h synthesis-time and (b) after HNO3 (cc) washing step. (c) Coalescence of small hexagonal particles seems to occur along [110] crystallographic direction as observed in the enlarged regions showed in (d). (e) High magnification HRTEM image of a coalescence area unambiguously confirms the crystallographic order becoming visible along the (110) direction. (f) Low magnification TEM image of a Sr4Mn3O10 particles stack on top of each other.

Referencias [1] D. Neagu, G. Tsekouras, D. N. Miller, H. Ménard, J. T. S. Irvine, “In situ growth of nanoparticles through

control of non-stoichiometry ”. Nature Chem., 5, (2013), 916-923. [2] V. F. Balakirev and Yu. V. Golikov, “Phase Relations in Alkaline Earth–Manganese–Oxygen Systems:

Equilibrium and Metastable States”. Inorg. Mater., 42, 1, (2006), S49-S69.

Characterization and fabrication of LSCF tapes

R. Fernández-González1,2,*, T. Molina3, S. Savvin1, R. Moreno3, A. Makradi2, P. Núñez1

1. Departamento de Química Inorgánica, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain 2. Centre de Recherche Public Henri Tudor, 29, avenue John F. Kennedy, L-1855 Luxembourg-Kirchberg, Luxembourg

3. Instituto de Cerámica y Vidrio, ICV-CSIC, Calle Kelsen 5, 28049 Madrid, Spain *ricardo.fernandez@tudor.lu

1. Introduction Mixed oxides of lanthanum, strontium, iron and cobalt (La1-xSrxCoyFe1-yO3-) with perovskite structure are good candidates for many devices such as solid oxide fuel cell (SOFC) due to their high mixed electronic-ionic conductivity and electrocatalytic activity [1], gas separation membranes [2] or catalysts for oxidation of hydrocarbons [3].This kind of perovskite membranes exhibits high oxygen permeability at elevated temperatures [4]. In this work the manufacture of commercial La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) by aqueous colloidal processing is presented. The surface behavior of LSCF as a function of pH and the effect of a polyelectrolyte (Duramax D3005) on the stability are studied using measurements of zeta potential. Concentrated suspensions were prepared to solid content as high as 35 vol.%. The best dispersing conditions were determined by means of rheological measurements for obtaining stable and fluid slurry for tape casting technique. Different relative densities of the tapes were obtained at different temperatures. The LSCF tapes are good candidates for using as gas separation membrane or cathode for SOFC. 2. Figures

Fig. 1. Zeta potential vs pH of LSCF commercial powder.

Fig. 2. Evolution of Zeta potential versus % of polyacrylic based deflocculant,measured as-prepared and 24 h later.

Fig. 3. Rheological behavior of 35 vol.% solid suspensions of LSCF prepared at different sonication minutes. 3. Conclusions The surface behavior study of LSCF commercial powder permits to determine that the isoelectric point of the material occurs at pH around 6 (Fig. 1). When suspensions are prepared to extreme pH values, they tend to stabilize by moving toward more neutral values. In general, suspensions cannot be prepared at acidic pH values because there is a significant dissolution of the cations that could change not only the surface behavior but also the composition and final properties of the material. The acidic suspensions are more stable than basic ones, but the largest solubility is obtained at pH 2; this is in opposition to the maximum zeta potential value measured at this pH and the relatively good stability of pH with time. The only possibility to explain the stability of these suspensions is that they contain significant concentrations of multivalent cations, that they could form complexes and do not remain free in the dispersing medium. So, to control the solubility and the stability it is necessary to avoid pH variations. Addition of a polyacrylic based deflocculant allows stable aqueous suspension, 0.3 wt% is enough for stabilize the slurry (Fig. 2). The ultrasounds study permits to control the thixotropy and obtain fluid suspensions for manufacturing LSCF tapes (Fig. 3). The temperature study allows knowing that the relative density is high, more than 99% at temperatures ranging from 1300ºC to 1400ºC, at lower temperatures the tapes are porous (less than 85% RD). As it was expected, at high temperature the LSCF reacts and form secondary phases that can reduce the ionic conductivity. Taking into account all the exposed on this work: the knowledge of LSCF rheological behavior, the manufacture of tapes and how the relative density evolves; allow us to propose this LSCF tapes as a good ion transport membrane or cathode material for future devices. 4. Acknowledgements We wish to thank financial support from Luxembourgish Government via FNR (project OMIDEF Grant FNR/786 643). We also thank to the Spanish Research Program through grant MAT2010-16007 and grant MAT2009-14369-C02-01. References [1] W.G. Wang, M. Mogensen, “High-performance lanthanum-ferrite-based cathode for SOFC”. Solid State Ionics, 176, (2005), 457–462. [2] H. Ullmann, N. Trofimenko, “Composition, structure and transport properties of pervoskite-type oxides”. Solid State Ionics, 119, (1999), 1–8. [3] U.B. Balachandran, B. Ma, “Mixed-conducting dense ceramic membranes for air separation and natural gas conversión”. Journal of Solid State Electrochemistry, 10, (2006), 617–624. [4] H.J.M. Bouwmeester, H. Kruidhof , A.J. Burggraaf, “Importance of the surface exchange kinetics as rate limiting step in oxygen permeation through mixed-conduction oxides”, Solid State Ionics 72, (1994), 185-194..

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Eu(III)-doped (Ca 0.7Sr0.3)CO3 phosphor as shock/tem perature detector

V. Blanco-Gutiérrez 1,*, V. Jubera 1,2, A. Demourgues 1, M. Gaudon 1,2,* 1. CNRS, ICMCB, UPR 9048, F-33600 Pessac, France

2 Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France *veroblangut@hotmail.com

Calcium carbonate (CaCO3) is one of the most abundant compounds in nature. It can be found in three allotropic forms with a different sphere coordination for the Ca2+ cation. Vaterite (S. G. P63/mmc) is the most kinetically favored phase, calcite (S. G. R-3c) the most stable at ambient conditions and aragonite (S. G. Pmcn) is obtained at high-pressure values and is metastable at ambient conditions with very slow kinetic of transformation into calcite phase. The transformation into the aragonite phase only occurs at very high pressure values1. However, it is possible to decrease this transformation pressure by doping the compound with Sr2+. In this case, the aragonite phase is stabilized2 due to the higher ionic radii and lower electronegativity of Sr2+ in comparison with Ca2+ cation. On the other hand, europium cation is one of the most employed luminescence activator due to its great optical propeties.3 The incorporation of Eu(III) into a (Ca,Sr)CO3 structure may be faisible taking into account the proximity of the Eu3+ ionic radii (0.95 Å, in octahedral site) in comparison to that of Ca2+ or Sr2+ (1.00 and 1.16 Å respectively, in octahedral site),4. In this work, metastable Eu(III)-doped (Ca0.7Sr0.3)CO3 vaterite has been easily prepared by the precipitation method. The metastable phase evolves to calcite when heating, and both vaterite and calcite phases transform into aragonite structure with pressure. The structural and microstructural characterizations of the samples have been performed by X-ray diffraction and transmission electron microscopy, respectively. Cell parameters are coherent with literature data of the extreme compositions CaCO3 and SrCO3 considering a Vegard law. Different luminescent properties have been found depending on the crystal structure due to the different geometrical site where is located the Eu(III). The microstructure seems to affect the luminescent properties as well. A scheme of phase transformation is represented in the Figure together with the photoluminescence emission spectra of the corresponding samples.

Fig.: Raw photoluminescence emission spectra for Eu(III)-doped (Ca,Sr)CO3 vaterite, calcite and aragonite

samples. It is shown as well an image of the three samples after being irradiated at 250 nm. By the employment of heat (T) or pressure (P) it is possible to obtain the different crystal structures.

The results lead to believe the obtained solid, as suitable material for temperature/shock detection. In addition, the three crystal structures containing the europium cation were treated under reducing conditions by the employment of CaH2. The major part of Eu(III) was reduced into Eu(II) and the used soft conditions allowed preserving the crystal structure for each case. Different luminescent spectra were also found for these samples. References [1] Carlson W.D., American Mineralogist., 65, (1980), 1252-1262. [2] Pan Y., Wu M., Su Q., Mat. Res. Bull. 38, (2003), 1537-1544. [3] Jubera V., Chaminade J., Garcia A., Guillen F., Fouassier C., J. Lumin. 101, (2003), 1-10. [4] Shannon, R.D. Acta Cryst., A32, (1976), 751–767.

Pressure effect on Mn2FeSbO6: Crystal structure-magnetic properties relationship

Elena Solana-Madruga1,*, Antonio J. Dos Santos-García2, Clemens Ritter3 and Regino Sáez-Puche1

1. Dpto. de Química inorgánica, Universidad Complutense de Madrid, Ciudad Universitaria, 28040. 2. Dpto. de Química Industrial y Polímeros, Universidad Politécnica de Madrid, C/ Ronda de Valencia, 3. 28012-Madrid.

3. Institut Laue-Langevin, 38042 Grenoble Cedex, France. *esolana@ucm.es

Compounds crystallizing with perovskite structure show a wide variety of properties, including superconductivity, magnetorresistance or thermoelectricity [1]. The ideal perovskite structure is accepted to have a tolerance factor t = 1, according to the Goldschmidt relation [2]. When t decreases, this ideal cubic structure gets distorted perovskites down to the limit value of t = 0.8. However, ABO3 compounds with t < 0.75 crystallize with corundum derivative structures, such as ilmenite (FeTiO3) or LiNbO3. [3]

On the other hand, it is well known that pressure can induce irreversible phase transformations, e.g. from ilmenite to perovskite structure, but also allows access to metastable phases at ambient pressure. [4]

High pressure is needed to stabilize A2MSbO6 (M = transition metal) double perovskites containing small A2+ site cations (e. g. Mn2+). This work aims study the polymorphism induced under high pressure and temperature conditions in Mn2FeSbO6 oxide. Perovskite and ilmenite polymorphs have been isolated and characterized by means of X-ray and high resolution neutron diffraction measurements. The study of the magnetic properties, through magnetization and magnetic susceptibility measurements at different temperatures and magnetic field strengths, reveal quite different magnetic behavior according to their different crystal structures.

The ilmenite polymorph has been synthesized at 5 GPa and 1473 K. X ray diffraction data show a rombohedral R-3 nuclear structure with a = 5.23 Å and c = 14.37 Å. Magnetic susceptibility measurements indicate a ferrimagnetic behavior with TN = 260 K, in agreement with the magnetic structure determined from neutron diffraction data taken at 150 K (Figure 1a, 1b). This structure can be described with a propagation vector k = [0 0 0], where the magnetic moments of 2Mn2+ and Fe3+ are antiparallel aligned giving, as result, a ferrimagnetic behavior with an experimental ordered moment of 4.2 μB, as it can be observed in Figure 1b. However, it is worth noting that a second magnetic transition has been observed for this compound below T = 50 K. Below this temperature, the magnetic structure adopts an incommensurate helical spin ordering ruled by a propagation vector k = [0 0 0.07] with the spins confined to the ab plane.

Increasing pressure up to 5.5 GPa during the synthesis process allowed the stabilization of the perovskite polymorph.[5] This compound crystallizes with a monoclinic P21/n structure with cell parameters a = 5.23 Å, b = 5.39 Å, c = 7.64 Å and β = 90.37º. The complex magnetic behavior studied from dc and ac magnetic susceptibility measurements has also been confirmed by neutron diffraction data. This polymorph develops, at a first sight, antiferromagnetic interactions below TN = 60 K. However the ac susceptibility data present a rounded maximum centered at 160 K, which cannot be attributed to long-range magnetic interactions, since there are not any noticeable changes in the PND data up and just below this temperature. Then, it can be associated to an energy dissipation process that can be explained as the result of the existence of short- range magnetic correlations which arise from ferromagnetic inhomogeneities in the solid. The magnetic structure at 2 K can be described in terms of an elliptical spiral with an incommensurate propagation vector k = [0 0.426 0], where spins are confined to the ac plane (Figure 1c).

Figure 1. a) Rietveld refinement of PND data taken at 150K for ilmenite polymorph. Bragg intensities correspond to the nuclear and magnetic structures (first and second rows) and Mn2Sb2O7 impurity phase. b) Magnetic structure of ilmenite polymorph at 150K. c) Magnetic structure of perovskite polymorph at 2K.

Throughout this work, a comparative study on the magnetic properties of different polymorphs of Mn2FeSbO6 oxide has been done. It is clear from the results that their magnetic properties strongly depend on their crystal structure. This affinity can be explained in terms of the different magnetic interaction paths induced by the change in the crystal structure: direct interactions can occur in the ilmenite polymorph while spins must couple via superexchange interaction through oxygen in the perovskite polymorph.

Acknowledgements:

The authors acknowledge funding from Comunidad de Madrid under the research project S-2009/PPQ-1626 and MICINN through MAT2010-19460. Authors are also indebted to Institut Laue-Langevin for beamtime allocation at D20, D1B and D2B instruments.

References: [1] E. Climent-Pascual, N. Ni, S. Jia, Q. Huang and R. J. Cava. Phys. Rev. B, 83, (2011), 174512. [2] V. M. Goldschmidt, T. Barth, G.Lunde and W. Zachariasen. Mat.-Nat. Kl, 2, (1926), 117. [3] R. H. Mitchell, “Perovskites. Modern and Ancient”. Almaz Press, Ontario (2002). [4] S. V. Ovsyannikov, A. M. Abakumov, A. A. Tsirlin, W. Schnelle, R. Egoavil, J. Verbeeck, G. Van Tendeloo, K. V. Glazyrin, M. Hanfland and L. Dubrovinsky. Angew. Chem. Int. Ed., 52, (2013), 1494. [5] A. J. Dos Santos-García, C. Ritter, E. Solana-Madruga and R. Sáez-Puche. J. Phys.: Condens. Matter, 25, (2013), 206004.

Reactive Ion Etching on (Yb,Nb):RbTiOPO4/RbTiOPO4 epitaxial layers for the

fabrication of Y-splitters and Mach-Zehnder Interferometers

M.A. Butt1, R. Solé1, M.C. Pujol1, A. Ródenas1, G. Lifante2, A. Choudhary3, G.S. Murugan3, D. Sheperd3, J.S. Wilkinson3, M. Aguiló1 and F. Díaz1

1. Física i Cristal·lografia de Materials i Nanomaterials (FiCMA-FiCNA) and EMaS, Universitat Rovira i Virgili (URV), Marcel·lí Domingo s/n, E-43007 Tarragona, Spain

2 Departamento de Física de Materiales, Universidad Autónoma de Madrid 28049 Madrid, Spain 3 Optoelectronics Research Centre, University of Southampton, Southampton,SO171BJ, United Kingdom

* mariacinta.pujol@urv.cat, rosam.sole@urv.cat

1. Introduction Rubidium titanyl phosphate RbTiOPO4 (RTP) belongs to a highly diverse and versatile structural family and because of its large non-linear optical coefficients, wide transparency, high laser damage threshold, high chemical stability and low dielectric constants, this material is highly attractive for electro-optic applications such as modulators and Q-switches [1]. RTP has a similar non-linear optical coefficient to KTP but, unlike KTP, it can be doped with Yb3+ ions to obtain a high enough concentration to allow efficient laser action [2]. Because of all these interesting properties, RTP is a strong candidate as a platform material for integrated photonics. Reactive ion etching (RIE) is a commonly used method in etching of semiconductors, but there is little literature available on the plasma-based etching of RTP. Moreover, single-mode rib waveguides have been successfully fabricated in (Yb,Nb):RTP by RIE [3]. In this work, (Yb,Nb):RbTiOPO4/RbTiOPO4 (001) epitaxial layers have been structured by RIE by using a combination of Ar and SF6 gases. The refractive index contrasts between the (Yb,Nb):RbTiOPO4 layer and the RbTiOPO4 substrate at 1.55 microns have been measured. 2. Experimental details RTP single crystals were grown by the top seeded solution growth-slow cooling (TSSG) technique to obtain thin plates of (001) oriented substrates. These substrates are well polished in order to have a smooth interface when epitaxial layers are grown over them. Liquid Phase Epitaxy (LPE) was used to obtain (Yb,Nb):RTP/RTP(001) in a well-isolated cylindrical vertical furnace with practically zero thermal gradient. Refractive indexes of the epitaxial layer and the substrate have been measured at 1550 nm with prism coupler method. After obtaining 6-7microns of epitaxial layer, a metal layer was deposited on it which acts as a hard mask during reactive ion etching. Different metal layers, for instance Al, Ti, Cr, Ni were tried to test their adhesion on the RTP and their performance as a metal mask. Channels designs were transferred by the help of conventional photolithography and the sample was etched with metal etchant to remove the unwanted parts of the metal mask. Finally, the samples with hard metal mask were put in a RIE Plasmalab 80Plus to etch. The process used was 250 W, 40 mTorr pressure and a gas combination of Ar (10 sccm) and SF6 (10 sccm), which was optimized in a previous work [3]. The dimensions of the designed structures were channels with widths from 6 to 9 microns and 5 microns depth. These dimensions were chosen in order to support a fundamental mode at wavelengths near 1520 nm. A thin layer of RTP was grown using the LPE technique at the end of fabrication process to act as a cladding for better light confinement, and also serves to lower the propagation losses. 3. Results and discussion Using the TSSG technique, we have obtained very high quality crystals with approx. 17x18x18 mm3 dimensions without any cracks and inclusions. The same is applicable for epitaxial layers grown with the LPE technique. Figures 1a) and 1b) show the RTP crystal and as grown (Yb,Nb):RTP/RTP epitaxial layer. The refractive index contrasts between the epitaxy and the substrate ( Δni=ni,epi-ni,sub being i=x,y and z) are: Δnx=-0.004, Δny=0.0003 and Δnz=0.005 allowing only monomode propagation in the TM polarization by choosing the appropriate channel waveguide dimensions. We have evaluated the Ti, Ni, Al and Cr elements as possible candidates for the metal mask by checking the adhesion of these metals to the RTP surface. The topography of the metal layer, analysed by AFM technique, showed average rms roughness of: 2.8 nm, 2.6 nm and 14 nm for Ti, Ni and Al layers, respectively. The adhesion and durability of the metal layer on RTP surface, was checked by several

tape test, and Aluminium shows the better adhesion. With RIE, a maximum etch rate of 8.5 nm/min for the epitaxial layer was obtained, and the deepest etch achieved was 2.8 m. Figure 2a) shows an ESEM image of a part of the MZI design etched on an epitaxial layer. The Liquid phase epitaxial growth of cladding shows a clear interface of growth, as shown in figure 2b).Optical waveguiding in the fundamental mode at a wavelength of 1520 nm was observed in the above mentioned MZI and Y-splitter rib waveguides with an etch depth of 2.8 m.

Fig.1: a) RTP single crystal, b) as grown (Yb,Nb):RTP/RTP epitaxial layer.

Fig. 2: a) ESEM image of the input section of MZI fabricated on (Yb, Nb): RTP/RTP; b) cross sectional view of MZI. 4. Conclusions Reactive ion etching was used to fabricate Y-splitters and MZIs on (Yb,Nb):RTP/RTP(001) samples. The maximum etch rate that we achieved with epitaxial layer was 8.5 nm/min and the maximum channel depth obtained was 2.8 microns. A thin cladding layer was grown over the channels for better confinement. These devices were designed to support fundamental mode of 1520 nm and the MZIs are expected to operate as modulators by using the E-O coefficient of RTP. Further investigation on this is in progress. 5. Acknowledgments This work was supported by the Spanish Government under Projects MAT2011-29255-C02-02, TEC2010-21574-C02-01, TEC2010-21574-C02-02, by the Catalan Authority under Project 2009SGR235 and by the European Union under Project No. FP7-SPA-2010-263044. M. Ali Butt thanks the Catalan Government for the FI-DGR fellowship 2012FI-B 00192. References [1].M.N. Satyanarayan, A. Deepthy, and H.L Bhat, ‘Potassium titanyl phosphate and its isomorphs: Growth, properties, and application,’ Crit. Rev.Solid State Matter. Sci., vol. 24, no. 2, (1999) 103-191. [2].X. Mateos, V. Petrov, A. Peña, J.J. Carvajal, M. Aguiló, F. Díaz, P. Segonds and B. Boulanger,’’Laser operation of Yb3+ in the acentric RbTiOPO4 codoped with Nb5+’’, Opt.Lett.32(13),(2007), 1929-1931. [3]. A. Choudary, J. Cugat, K. Pradesh, R. Solé, F. Díaz, M. Aguiló, H.M.H. Chong and D.P. Shepherd, ‘’Single-mode rib waveguides in (Yb,Nb):RbTiOPO4 by reactive ion etching’’, J. Phys. D: Appl. Phys. 46 (2013), 145108 (6pp).

Ni-doped karrooite yellow-orange ceramic pigments prepared by ceramic and citrate gel routes

M. Llusar *, E. García, M.T. García, C. Gargori, J. A. Badenes y G. Monrós Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, 12071, Castellón, Spain

*mllusar@uji.es 1. Intro duction and objectives Titanium pseudobrookites (M3+

2(1-x)M2+

xTi1+xO5 or [M3+,M2+,Ti]M1[Ti,M2+,M3+]M22O5, i.e. FeTi2O5,

MgTi2O5, Fe2TiO5, Al2TiO5, Cr2TiO5, Ti3O5, etc.) are isostructural phases with orthorhombic symmetry (Cmcm spatial group) and a high structure flexibility to accommodate different chromophore metals in their two different and distorted octahedral cationic sites, M1 or A (4c) and M2 or B (8f) [1]. Indeed, some patents about yellow pigments based on Ti pseudobrookites have been already developed in the last decades (Rademachers, Hund, Katamoto, Suzuki; 1977-2003) [2], although they were basically prescribed for low-temperature applications (paints, plastics, resins, etc). This extraordinary structural versatility of Ti pseudobrookites, along with their high refractoryness (1650ºC) and refractive indexes (2.35-2.42), has also driven some investigations on their possible application as host structures for ceramic pigments. For instance, Matteucci et al [3] studied recently the crystal structure and optical properties of ceramic pigments based on Mg-Ti pseudobrookite (karrooite) Mg1-xM2xTi2-xO5 solid solutions prepared by the conventional ceramic route (1200-1400ºC; M = VIV, CrIV, Mn2+-Mn3+, Fe3+, Co2+ or Ni2+), and found that they were mostly stable in low-temperature (≤1050°C) ceramic glazes and glassy coatings. In the case of Ni doping, quite intense yellow colorations with a certain orange cast were obtained (L*/a*/b* values of 73.7/8.1/39.8 for powders with 10 mol-% Ni). However, only two compositions were analyzed (x = 0.02 and 0.05) and neither the solid solution limit of Ni in MgTi2O5 karrooite nor the possible tuning of the yellow-orange color shade and intensity by Ni-doping were investigated. With all the above precedents, solids solutions of Ni in MgTi2O5 pseudobrookite (karrooite) prepared by the ceramic method have been herein investigated in depth for the first time aiming to develop new yellowish-orange ceramic pigments. In addition, it has been also analyzed the effect of using a more homogeneous and reactive metalorganic decomposition route (MOD or citrate gel) [4] on the crystallization, microstructure, stability and coloring performance of Ni-MgTi2O5 solid solutions. To this respect, the decomposition (combustion) of citrate-based coprecipitates or polymeric xerogels leads to the formation at lower temperatures of more homogeneous multicomponent powders (mixed oxides), which often exhibit nanostructured (submicronic) morphologies [4a-b], which are demanded to fulfill the requirements of ceramic inks used in the new (ink-jet) decoration technologies of ceramic tiles [5]. 2. Experimental and Results Ni-Karrooite solid solutions (Mg1-xNixTi2O5, 0≤x≤1) were prepared by the conventional ceramic method and also by a citrates gel metalorganic route [4], using rapid firing conditions (5ºC/min-heating and 3h-soaking) up to a maximum temperature between 800-1500ºC. Fired pigments were characterized by XRD, SEM/EDX, UV-vis-NIR and color measurement (CIE-L*a*b*) techniques. According to XRD results, the solid solubility of Ni in karrooite was only partial and strongly temperature-dependent: around 40 mol-% of Ni at 1200ºC and 60-65 mol-% at 1400ºC, irrespective of the preparation route. Thus, it seems that Ni doping reduces to some extend Mg2+/TiIV cation disorder and the entropy-stabilization of MgTi2O5 pseudobrookite with respect to the most stable ilmenite (MgTiO3) and rutile (TiO2) phases. Optical absorptions of Ni2+ ions in distorted octahedral sites of karrooite produced intense yellowish-orange colors, increasing saturation (lower L*) and chroma (higher red –a*- and yellow –b*- hues) with temperature and Ni doping (Fig. 1a-b). These pigments developed nice yellow colorations once enameled (5 wt-%) within low temperature (1000-1050ºC) ceramic glazes (Fig. 1c-d), being much less stable in a Ca- and Zn-enriched glaze (glaze A). Noteworthy, the citrate MOD route enabled the stabilization of Ni-karrooite solid solutions at lower temperatures (1000ºC, 20 mol-% of Ni) and produced finer-grained powders with slightly more intense orange hues (L*/a*b* color parameters of 1400ºC-fired powders for x=0.6 were 61.4/24.7/45.9 and 62.3/23.9/51.3 for ceramic and MOD-citrate samples, respectively). However, the yellow color of enameled samples was very similar in both routes (L*/a*/b* values for 1400ºC-fired powders with x=0.6 were 60.0/10.8/51.6 and 59.2/9.9/49.7 for ceramic and MOD-citrate samples, respectively).

3. Acknowledgments The authors would like to acknowledge the financial support provided by the Spanish “Ministerio the Economía y Competividad” (MAT2012-36988-C02-01 project).

x = 0 x = 0.1 x = 0.2 x = 0.4 x = 0.5 x = 0.6 x = 0.7 x = 1.0

1000ºC/3h

(direct)

1200ºC/3h

(direct)

1400ºC/3h

(refired)

x = 0 x = 0.1 x = 0.2 x = 0.4 x = 0.5 x = 0.6 x = 0.7 x = 0.8(d) x = 1.0

1400ºC/3h

(direct)

1500ºC/3h

(direct)

x = 0.6 x = 0.8 x = 1.0 x = 0.6 x = 0.8 x = 1.0

1200ºC

(Glaze A)

x = 0.1 x = 0.2 x = 0.4 x = 0.7 x = 1.0

1200ºC

(Glaze B)

1400ºC

(Glaze B)

x = 0 x = 0.1 x = 0.2 x = 0.4

x = 0.5 x = 0.6 x = 0.7 x = 1.0

800ºC

1000ºC

1200ºC

1400ºC

x= 0 x= 0.1 x= 0.2 x= 0.4 x= 0.6

Ni-MgTiO3

+ Ni-TiO2

Ni-MgTi2O5

1000ºC

(Glaze B)

x = 0 x = 0.1 x = 0.2 x = 0.4 x = 0.6

1200ºC

(Glaze B)

1400ºC

(Glaze B)

Fig. 1: Color evolution of fired powders (a and b) and 5 wt-% enameled samples (c and d) corresponding to Mg1-xNixTi2O5 karrooite compositions prepared by the ceramic (a and c) and MOD-Citrate routes (b and d).

Referencias [1] a) L. Pauling, “The crystal structure of pseudobrookite”, Z Kristallogr, 73 (1930), 97-112; b) S. Akimoto, T.

Nagata, T. Katsura, “The TiFe2O5-Ti2FeO5 solid solution series”. Nature, 179, (1957), 37-38; c) G. Bayer, “Thermal expansion characteristics and stability of pseudobrookite-type compounds, Me3O5”. J Less-Common Metals, 24 (1971), 129-138; d) J.F.W. Bowles, “Definition and range of composition of naturally occurring minerals with the pseudobrookite structure”. Am Mineral, 73, (1988), 377-383.

[2] a) J. Rademachers, H. Erfurth, F. Hund, “Metal additions to pigments of pseudobrookite-titanium dioxide structure”. US patent 4,036,662, (1977); b) F. Hund, W. Holznagel, H. Erfurth, F. Kindervater, W. Hennings, “Temperature-stable inorganic yellow pigments”. US patent 4,084,984, (1978); c) T. Katamoto, M. Fujimoto, “Heat-resistant yellow pigment with pseudobrookite structure of the formula Fe(2-p-q-r-s)Li(p)Mg(q)Al(r) Ti(s)O5”. European Patent 949, 2022, (1999); d) T. Suzuki, K. Kataoka, “Titanium-iron based composite oxide pigment and method for production thereof”. US patent 6,540,824, (2003).

[3] F. Matteucci, G. Cruciani, M. Dondi, G. Gasparotto, D.M. Tobaldi, “Crystal structure, optical properties and colouring performance of karrooite MgTi2O5 ceramic pigments”. J Solid State Chem, 180, (2007), 3196-3210.

[4] a) C. Gargori, R. Galindo, S. Cerro, M. Llusar, A. García, J. Badenes, G. Monros, “Ceramic pigments based on chromium and vanadium doped CaTiO3 perovskite obtained by metal organic decomposition (MOD)”. Bol Soc Esp Ceram Vidr, 51 (2012), 343-352; b) M. Blosi, S. Albonetti, M. Dondi, A.L. Costa, M. Ardit, G. Cruciani, “Sol-gel combustion synthesis of chromium doped yttrium aluminum perovskites”. J Sol-Gel Sci Technol, 50 (2009), 449-455; c) R.D. Purohit, S. Saha, “Synthesis of magnesium dititanate by citrate gel route and its characterization”. Ceram Int, 25 (1999), 475-457.

[5] G. Monrós, J.A. Badenes, A. García, M.A. Tena, en “El color de la cerámica: Nuevos mecanismos en pigmentos para los nuevos procesados de la industria cerámica”, pp. 146-179, ed. Universitat Jaume I, Castelló de la Plana, 2003 (ISBN 84-8021-449-X).

(c) Ceramic route

(d) MOD-Citrate route

(a) Ceramic route

(b) MOD-Citrate route

Oral communication

About the degradation of Na2SiF6:Mn4+ phosphor for WLED applications

Anthony Barros1,2,, Geneviève Chadeyron2, Philippe Boutinaud2, Rodolphe Deloncle1, Jérôme Deschamps1, Rachid Mahiou3

1. RevLum SAS, 8 rue des Frères Lumière, 63100 Clermont-Ferrand, France 2. Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10187, 63174 Aubière Cedex, France

3. CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, BP 80026, 63171 Aubière Cedex, France anthony.barros@univ-bpclermont.fr

It has been shown recently that the red luminescence of Mn4+ ions in fluorides could be of interest for the WLED technology [1-3]. In compounds like Na2SiF6 or K2SiF6, for instance, the Mn4+ ion experiences a strong crystal field resulting in a sharp and intense red emission (≈ 620 nm) from the 2Eg state upon blue excitation (≈ 420 – 460 nm) in the 4T2g multiplet (Fig. 1). However, when these phosphors are exposed to air atmosphere for a few tens of hours at 200°C, severe degradation of their optical properties is observed (Fig. 1). This drawback limits significantly their applicability in LED devices. The purpose of the present work is to investigate the origin of these degradations and finalize a chemical treatment that could improve the durability of the phosphors in the device. Results in X-ray diffraction, ESR, NMR (Si, F), FTIR and optical spectroscopy will be presented in this connection.

Fig. 1: Na2SiF6 : Mn4+ before and after aging at 200°C during 2 days in air atmosphere.

References

[1] E. V. Radkov, L. S. Grigorov, A. A. Setlur, A. M. Srivastava, United States Patent Application US2006/0169998 A1.

[2] M. G. Brik, A. M. Srivastava, Journal of Luminescence, 133, 2013, 69.

[3] Yan Kai Xu, Sadao Adachi, Journal of Applied Physics, 105, 2009, 013525.

Conferencia oral

Synthesis and deposition of CZTS nanoparticles using a solvothermal method

Ivan Calvet1,*, Rafael Martí1, Diego Fraga1, Aitor Rey1, Ester Barrachina1, Radostina Dimova1, Teodora Stoyanova1 and Juan B. Carda1

1. Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón *icalvet@uji.es

1. Introduction Nowadays the development of solar photovoltaic renewable energy has increased rapidly , due to an higher demand of cleaner energy consumption. Chalcogenides are important semiconductors, presenting unique optical, electrical and chemical characteristics. Due to this wide range of properties, in the last years chalcogenides have attracted the attention of the scientific community, particularly in thin films technology, being heavily promoted by the growing interest in CIGS and CZTS -­‐ based solar cells. Several chemical routes have been studied for CZTS synthesis like hot injection, sol-gel, electrodeposition, and so on [1] The Cu2ZnSnS4 system (CZTS), which crystallizes in the Kesterite structure, is one of the most promising materials for thin films, because it has a "band gap" of 1.5 eV and a high absorption coefficient (104 cm-1). Also, such a system is sustainable and environmental friendly due to the absence of toxic elements, together with a significant cost savings due to the incorporation of low cost and abundant raw materials (Zn and Sn). The as-synthetized CZTS nanoparticles could be used in the form of ink and could be coated on a ceramic substrate in order to obtain a photovoltaic device which provides added value to the traditional ceramic tile. [2-5]. In this work, it has been studied the synthesis of Cu2ZnSnS4 by a facile solvothermal method. In order to improve the preparation procedure different precursors and thermal treatments were studied. Stoichiometric composition, structure, morphology and absorption characteristics of CZTS nanoparticles were analyzed. Moreover, it has been studied different organic solvents to form a stable ink of CZTS. The obtained ink was deposited on the ceramic substrate and the heat treatment used was set in an chalcogenides atmosphere for obtaining the final compound. The materials were analyzed via X-ray diffraction (XRD), Scanning electron microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDAX), Surface profiler (SP) and etc. in order to clarify their properties. References [1] David B.Mitzi , Oki Gunawan,Teodor K.Todorov,Kejia Wang,Supratik Guha, The path towards a high-performance solution-processed kesterite solar cell, Solar Energy Materials & Solar Cells, 95, pp.1421–1436 (2011)

[2] S.Delbos, Kesterite thin films for photovoltaics: a review, EPJ Photovoltaics 3, pp.35004 (2012)

[3] C.P. Chan, H. Lam, C. Surya, Preparation of Cu2ZnSnS4 films by electrodeposition using ionic liquids, Solar Energy Materials Solar Cells, 94, pp.207-211 (2010)

[4] W. Xinkun, L. Wei, C. Shuying, L. Yunfeng, J. Hongjie, Photoelectric properties of Cu2ZnSnS4 thin films deposited by thermal evaporation, Journal of Semiconductors, 33, 022002 (2012)

[5] T.K Todorov, J.Tang,S.Bag, O.Gunawan, Y.Zhu, D.B.Mitzi, Beyond 11% Efficiency: Characteristics of State-of-the-Art Cu2ZnSn(S,Se)4 Solar Cells, Advanced Energy Materials 3 pp.34-38 (2012)

oral

Eco-energy lighting based on the combination of LEDs withOrganic Phosphors

Rachod Boonsin1, Genevière Chadeyron1,*, Jean-Philippe Roblin1, Damien Boyer1 et Rachid Mahiou1,2

1. Clermont Université, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND

2. CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, BP80026, F-63171 AUBIERE *genevieve.chadeyron@ensccf.fr

Introduction

Nowadays, the lighting market has a main concern about the effect of products toward the environment. The present technology has become obsolete: high energy consumption (incandescent bulbs) and high toxic substances (compact fluorescent light bulbs). Therefore, several strategies have been investigated to overcome these drawbacks [1-4]. One of the most promising approaches is the system based on white light-emitting diodes (WLEDs) obtained by combining a blue and/or UV LED with some phosphors in order to achieve the specifications of public lighting (low energy consumption, long lifetime, etc.). However, the phosphors used in LEDs involve rare-earth elements with very inconstant fares since China is the leader of the production of these latters (97%). Hence, the rare-earth-free organic phosphors become an alternative solution because of their high luminous efficiency, low cost of production, and several ways to tune the colors by playing with their functional groups.

In this work, we have synthesized three rare-earth-free organic phosphors based on 2,6-

diméthyl-4-pyrone [5] and Schiff base ligand [6]. Herein we describe the synthesis procedures and we present the morphological and optical characterizations. The optical performances of these organic phosphors upon ultraviolet and blue excitations will be discussed.

Acknowledgement This work is financially supported by the Regional Council Auvergne (FRANCE). References [1] S.-Y. Kwak, S. Yang, N.R. Kim, J.H. Kim, B.-S. Bae, “High color rendering White light-emitting diodes base

don a Green silicate phosphor mixed with a red dye-bridged hybrid”. The Royal Society of Chemistry Advances, 2, (2012), 12371-12377.

[2] T. Jüstel, H. Nikol, C. Ronda, “Periodic table of the lighting elements”. Angewandte Chemie International Edition, 37, (1998), 3084-3103.

[3] D.-H. Hwang, J.-D. Lee, H.J. Cho, N.S. Cho, S. K. Lee, M.-J. Park, H.-K. Shin, C. Lee, “Organic white light-emitting diodes using a new DCM derivative as an orange-red doping molecule”. Synthetic Metals, 158,

(2008), 802-809. [4] S.-T. Lim, M.H. Chun, K.W. Lee, D.-M. Shin, “Organic light emitting diodes with red emission using (2,6-

dimethyl-4H-pyran-4’ylidene)malononitrile moiety”. Optical Materials, 21, (2002), 217-220. [5] L.L. Woods, “Some further reactions of 2,6-dimethyl-4-pyrone”. Journal of the American Chemical Society,

80, (1958), 1440-1442. [6] Z.-C. Chuan, Z.-Y. Yang, Y. Li, B.-D. Wang, Q.-X. Zhou, “A simple structure fluorescent chemosensor for

high selectivity and sensitivity of aluminium ions”. Dyes and Pigments, 97, (2013), 124-128.

Estudio de nano-pigmentos basados en TiO2

dopado con Cr y Sb para su aplicación en

tecnología inkjet

Marc Jovani, Maria Domingo, Thales Machado, Héctor Beltrán Mir, Eloísa Cordoncillo*

1Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón, Campus del Riu Sec, E-12071,

Castellón de la Plana, Spain * cordonci@uji.es

El dióxido de titanio es un material multifuncional con un gran número de aplicaciones (pinturas,

cremas, pastas de dientes, pigmentos etc). Actualmente el campo de la nanotecnología ha

despertando un gran interés debido a las nuevas aplicaciones que puede generar. En este

sentido, y más estrechamente en el sector de los nano-pigmentos, el TiO2 tiene un gran

número de aplicaciones. El uso de nanopartículas para incorporarlas como pigmentos en

impresoras inkjet va a resolver algunos problemas surgidos actualmente.

La denominada “química suave” en la síntesis de nanopartículas, es usada en gran medida no

solo por su sencillez, sino también por la posibilidad de control de las características de las

nanopartículas, modulando los parámetros de reacción.

En este estudio, se han obtenido nanopartículas del pigmento basado en TiO2 dopado con

Cr(III) y Sb(III,V) mediante métodos solvotermales a partir de microemulsiones. Se ha obtenido

fase única de rutilo y anatasa a bajas temperaturas, así como partículas esféricas, controlando

los parámetros de reacción tales como el pH, temperatura, tiempo de reacción, cantidad de

cromóforo etc. Las coloraciones obtenidas de estas nanopartículas obtenidas a temperaturas

inferiores a 200ºC fueron semejantes a las de los pigmentos industriales obtenidos a altas

temperaturas (>1100ºC) obtenidas por el método cerámico.

Los nano-pigmentos obtenidos, tanto por su coloración como por su morfología, son

potencialmente utilizables en la industria inkjet, pudiendo eliminar actuales problemas del

método utilizado en la industria cerámica (aglomeración, inestabilidad etc.), así como

reduciendo costes con la eliminación de algunas etapas como la de molturación para la

obtención de tamaños pequeños de partícula.

A novel series of [(CH3CH2CH2)4N][M(N(CN)2)3] (M: Mn2+, Fe2+, Co2+, Ni2+, Cd2+) perovskite-like

coordination polymers with dielectric properties Juan Manuel Bermúdez-García1,*, Manuel Sánchez-Andújar1, Susana Yáñez-Vilar2,

Jorge Mira2, Alfonso Fondado2, Jorge López-Beceiro3, Ramón Artiaga3, Socorro Castro-García1 and María Antonia Señarís-Rodríguez1

1. Dpt. Fundamental Chemistry, University of A Coruña, Campus A Coruña, 15071 A Coruña, Spain 2. Dpt. Applied Physics, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain

3. Dpt. Industrial Engineering II, University of A Coruña, Campus Ferrol, 15403 Ferrol, Spain *j.bermudez@udc.es

1. Introduction Perovskite materials exhibit a general formula ABX3, where A are lanthanides, alkaline earth metals or similar cations, B are transition metals cations and X can be different types of anions as O2-, S2-, halides or, even, polyatomic ligands. As it is well-knwon the perovskite structure can be defined as a tridimensional network of [BX6] octahedra sharing corners, with the A cations situated in the resulting cubooctahedral cavities. Traditionally, the studies about perovskite compounds have focused on inorganic materials, mainly transition metal oxides of general formula ABO3, which constitute a wide class of compounds that display an amazing variety of interesting properties. This perovskite family encompasses insulators, piezoelectrics, ferroelectrics, semiconductors, magnetics, superconductors, multiferroic and magnetoresistive materials. Much less effort has been devoted to the study of hybrid inorganic-organic compounds and coordination polymers with perovskite-like structure that contain organic or inorganic polyatomic ligands in the X position. Nevertheless, these compounds are attracting increased attention in view of the interesting functional properties they can display. In this context, a new series of perovskite-like materials with general formula [G][M(HCOO)3] have been mainly studied due to their interesting magnetic, dielectric and even multiferroic properties.1,2 From the structural point of view, all these compounds have 3D-structures consisting on [M(HCOO)3]- frameworks (where M2+ is typically a 3d transition metal cation) counter-balanced by alkylammonium cations [G] located in the pseudocubooctahedral cavities and hydrogen-bonded to the framework. The size, shape and charge of the alkylammonium cations, acting as templates, determine the topology of the framework. Such [G][M(HCOO)3] compounds are very adequate to study important functional properties, just as for example magnetic and dielectric properties. In this context, the 3D-structure of their framework is adequate to get long-range magnetic coupling of the metal cations, while the presence of disordered alkylammonium cations inside the pseudocubooctahedral cavities allow the appearance of dielectric properties.3

Figure 1.-Perovskite-like structure of [G][M(N(CN)2)3] (G: tetrapropylammonium, M: Mn2+, Ni2+, Fe2+, Co2+, Cd2+).

Recently, we have focused on the coordination polymer perovskites of general formula [G][M(N(CN)2)3] with dicyanamide N(CN)2- as ligand which bridged M2+ (transition metal cations) forming a [M(N(CN)2)3]- framework and alkylammonium cations [G] located in the cavities (see figure 1). In the literature, the crystal structure and the magnetic properties of several dicyanamide perovskites have been reported but to our knowledge the dielectric behavior of these compounds has not been reported. It is the case of [(CH3CH2CH2)4N][M(N(CN)2)3] (M= Mn2+(1) and Ni2+(2)) compounds, whose synthesis, crystal structure and magnetic properties were reported by Schlueter et al.4 These authors reported that the Ni2+(2) compound shown two structural transitions at 160 K and 210 K, which are due to a transformation from a centrosymmetric (Pnna) to a non centrosymmetric space group (P-421c). The Ni2+(2) compound shows an orthorhombic symmetry (space group Pnna) at T> 210 K and T<160 K and a tetragonal symmetry (space group P-421c) in the temperature range of 160<T(K)<210. In the present work, and for the first time, we report the dielectric response of the series [(CH3CH2CH2)4N][M(N(CN)2)3] with M= Mn2+(1) Ni2+(2), Fe2+(3), Co2+(3), and Cd2+(5) containing tetrapropylammonium cations. Also, we deep in the structural and dielectric characterization of this novel series of perovskite-like compounds. It should be remarked that Fe2+(3), Co2+(4) and Cd2+(5) compounds have been synthesized for the first time in this work and that we also have found a new phase for the Mn2+(1) compound at 368 K, and two new phases for the described Ni2+(2) compound at 323 K and 368 K, respectively. In addition, we have observed that the structural transitions induce dielectric anomalies in all of these compounds. We suggest that a displacement of the tetrapropylammonium cations inside the pseudocubooctahedral cavities and a disorder in the dicyanamide anions are involved in the dielectric and structural transitions. 2. Conclusions In summary, we have synthesized and characterized a novel series of [(CH3CH2CH2)4N][M(N(CN)2)3] (M: Mn2+, Ni2+ Fe2+, Co2+, Cd2+) compounds which have several structural transitions. These structural changes are due to the tetrapropylammonium cations displacement inside the pseudocubooctahedral cavities and the disorder of the dicyanamide anions, that induce dielectric transitions in these materials. 3. Acknowledgments The authors are grateful for financial support from Ministerio de Economía y Competitividad (MINECO) (Spain) and EU under project FEDER MAT2010-21342-C02-01 4. References [1] P.Jain, V, Ramachandran, R.J. Clark, H. D. Zhou, B.H. Toby, N.S. Dalal, H.W. Kroto, A.K. Cheetham,

“Multiferroic Behavior Associated with an Order−Disorder Hydrogen Bonding Transition in Metal−Organic Frameworks (MOFs) with the Perovskite ABX3 Architecture”. Journal of the American Chemical Society, 131, (2009), 13625-13627

[2] W. Li, Z. Zhang, E.G. Bithell, A.S. Batsanov, S. Andrei, P.T. Barton, P.J. Saines, J. Paul, P. Jain, C.J. Howard, M.A. Carpenter, A.K. Cheetham, “Ferroelasticity in a metal–organic framework perovskite; towards a new class of multiferroics”. Acta Materialia, 61, 13, (2013), 4928-4938.

[3] M. Sánchez-Andújar, S. Presedo, S. Yáñez-Vilar, S. Castro-García, J. Shamir, M.A. Señarís-Rodríguez, “Characterization of the Order−Disorder Dielectric Transition in the Hybrid Organic−Inorganic Perovskite-Like Formate Mn(HCOO)3[(CH3)2NH2]”.Inorganic Chemistry, 49, (2010), 1510-1516.

[4] J.A. Schlueter, J.L. Manson, U.Geiser, “Structural and Magnetic Diversity in Tetraalkylammonium Salts of Anionic M[N(CN)2]3- (M = Mn and Ni) Three-Dimensional Coordination Polymers”. Inorganic Chemistry, 44, (2005), 3194-3202.

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Lead halide perovskites as light harvesters materials for solar cells

Emilio J. Juárez-Pérez, Victoria Gonzalez-Pedro, Iván Mora-Sero, Juan Bisquert

Photovoltaics and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071 Castelló, Spain Email: bisquert@uji.

1. Introduction Recently, a new type of photovoltaic cells with lead halide perovskites as light harvester materials have rised onto the scene receiving great attention in the scientific community. It is due mainly because a fast succession of record devices in a short time period, which it is now reaching above of 16 % power conversion efficiency (PCE).[1] The light- absorbing semiconductor material is based on a hybrid (organic/inorganic) halide perovskite polycrystalline structure with formula AMX3, where A is a small organic cation (methylammonium, formamidinium), B is a metal cation (Pb

2+, Sn

2+) and X is a halide element (I, Cl, Br, or a combination

of some of them). Lead halide perovskites have been used as light harversters since 2008 when Miyasaka et al.[2] reported that these materials could be an alternative to binary chalcogenide based quantum dots sensitized cells. However, the liquid electrolyte used as hole transport layer rapidly degraded the active material of sensitized cell. The breakthrough in efficiency (9.7%) and stability (> 500 hours) was done by Park and collaborators in 2012 by replacing the liquid electrolyte by a solid one, the spiro-OMeTAD,[3] see Figure 1.a for a general schema of the device. At the same time, Snaith et al. assembled devices whose active layer was deposited inside an insulator scaffold material as Al2O3 reached PCE profiles of 10.9%[4] meaning that the harvesting material itself conduct the generated photocurrent. Later, the same group reported planar heterojunction devices without mesoporous layer reaching even higher PCE. Therefore, the proficient operation of the APbX3 perovskite solar has been accomplished by many different approaches pointing out for an underlying robust photovoltaic operation mechanism. 2. Easy manufacture of solid state photovoltaic devices using wet methods An interesting aspect of the manufacture of these photovoltaic devices is that the active material is solution processable using common lab solvents and the active layer can be deposited using spin and/or dip coating procedures at room conditions without employ vacuum techniques. Scheme 1 summarizes the current main methods used for perovskite deposition and Figure 1.b depict the step-by-step process to assemble a lab prototype device. It is important to note that from the point of view of the manufacturing the sequential method offers a more efficient use of the reagents and economically feasible techniques to produce cells at industrial scale. It consists of a first stage of spin-coating a concentrated PbI2 solution in a mesoporous layer of TiO2 followed by a second stage of dip-coating the substrate in the organic salt solution or atmospheric vapour deposition (VASP process) to synthesize in situ the hybrid halide perovskite. The configuration stacks currently reported include the normal and the inverted configurations using glass or plastic substrates which reflect versatility of this solar harvesting material for photovoltaic applications. Furthermore, different halide elements have

Figure 1

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been combinated in different proportions to tailor the Voc of the device. Also, different organic cation counterpart and first attempts to replace Pb by Sn are being reported.[5]

Scheme 1: Main active layer deposition methods for hybrid halide lead perovskites.

3. Impedance Spectroscopy: characterization to improve perovskite photovoltaic devices. An understanding of the mechanisms of transport and accumulation of charges and working principles is highly mandatory to assess the possibilities and properties of these materials.[6] Therefore, for further development of these photovoltaic devices it is required to determine the fundamental operational mechanism of the different layers constituting the device. For example, to obtain a deeper insight of the role of selective contact in the performance of perovskite solar cells, impedance spectroscopy (IS) is a technique capable to discriminate between the different components of the device and consequently it is able to provide abundant and useful information on the device working mechanism. IS determined recently that both electron- and hole- selective contacts significantly affect the solar cell performance playing three major roles: transport resistance at the selector layer, charge-transfer rate at the interface and control the recombination resistance in the perovskite layer.[7] The most important parameter characterizing the active layer of a solar cell is the diffusion length, it plays a key role in the photovoltaic performance of perovskite solar limiting the useful active layer thickness. Because IS spectra of perovskite based full devices show the transmission line feature, diffusion length, carrier conductivity and recombination resistance can be straightforwardly extracted.[8]

4. Conclusions Over a short period of research time there have been scientific teams looking for the highest efficencies, novel cell architectures or diving in the mechanisms of transport and accumulation of charges for the halide perovskite based solar cells. A fast, cheap, unsupervised batch-wise operation and non-invasive technique to characterize full devices is mandatory to overcome in the next years the plethora of promising active materials and configurations paralleling the properties of the hybrid halide perovskites for photovoltaics applications. Impedance spectroscopy meets these requeriments and will help to reach the efficiency limits of these light harvesting materials. 5. Acknowledgments This work was supported by Generalitat Valenciana (ISIC/329 2012/008) and Universitat Jaume I project 12I361.01/1. Referencias [1] NREL best cell efficiencies. http://www.nrel.gov/ncpv/images/efficiency_chart.jpg visited on 13/03/2014 [2] A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, J. Am. Chem. Soc. 2009, 131, 6050-6051. [3] H.-S. Kim, C.-R. Lee, J.-H. Im, K.-B. Lee, T. Moehl, A. Marchioro, S.-J. Moon, R. Humphry-Baker, J.-H. Yum, J. E. Moser, M. Gratzel, N.-G. Park Nat. Sci. Rep. 2012, 2, 591-7. [4] M. M. Lee, J. Teuscher, T. Miyasaka, T. N. Murakami, H. J. Snaith, Science 2012, 338, 643-647. [5] H.-S. Kim, S. H. Im, N.-G. Park, J. Phys. Chem. C DOI: 10.1021/jp409025w [6] H.-S. Kim, I. Mora-Sero, V. Gonzalez-Pedro, F. Fabregat-Santiago, E. J. Juarez-Perez, N.-G. Park, J. Bisquert, Nature Communications 2013, 4, 2242. [7] E. J. Juárez-Pérez, M. Wussler, F. Fabregat-Santiago, K. Lakus-Wollny, E. Mankel, T. Mayer, W. Jaegermann, I. Mora-Sero J. Phys. Chem. Lett. 2014, 5, 680-685. [8] V. Gonzalez-Pedro, E. J. Juarez-Perez, W.-S. Arsyad, E. M. Barea, F. Fabregat-Santiago, I. Mora-Sero, J. Bisquert Nano Lett. 2014, 14, 888-893.

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Recubrimientos Nanométricos Funcionales mediante Spray Pyrolysis

Mª Dolores Palacios*, J.Luis Amorós, Encarna Blasco y Sergio Mestre Instituto de Tecnología Cerámica.

Asociación de Investigación de las Industrias Cerámicas. Universitat Jaume I. Avda. Vicent Sos Baynat. s/n, 12006 Castellón. España.

*lola.palacios@itc.uji.es Se ha estudiado la formación de capas nanométricas sobre un sustrato cerámico partiendo de una disolución o suspensión acuosa. La aplicación mediante aerografía de una disolución acuosa de una sal de un metal sobre un sustrato caliente, en determinadas condiciones da lugar a una nanocapa, que puede modificar las propiedades funcionales y/o estéticas la superficie cerámica. Este método de deposición, convenientemente escalado, puede resultar más económico y más polivalente frente a técnicas como la Deposición Química en fase Vapor (CVD) y la Deposición Física en fase Vapor (PVD), que requieren un equipamiento más sofisticado.

Figura 1. Esquema básico de un sistema de spray pyrolysis.

Las disoluciones acuosas se formulan a partir de sales metálicas muy solubles en agua, como son los nitratos de aluminio, cobre, cobalto, manganeso, hierro o plata entre otros. Para elementos, como el titanio, del que no existe este tipo de sales fácilmente manipulables, se han tenido que sintetizar complejos solubles en agua para tal efecto. El resultado son capas de óxidos de los elementos precursores que modifican el aspecto y la microestructura de las superficies.

Se han estudiado las variables que influyen sobre el proceso de formacion de la nanocapa con el objetivo de poder predecir los materiales que pueden depositarse sobre un determinado vidriado cerámico, y en su caso las condiciones de operación necesarias para conseguir la nanocapa. En este sentido, variables como la naturaleza del precursor líquido, la temperatura, naturaleza del vidriado, la temperatura de aplicación o el volumen de precursor depositado, pueden resultar decisivas para obtener la nanocapa, y a su vez influir sobre las propiedades estéticas y/o funcionales de la misma.

Este estudio ha permitido determinar los parámetros de los que depende la compatibilidad entre el precursor y el sustrato, la formación de la nanocapa, así como generalizar la aplicación del proceso gracias al conocimiento de las variables implicadas. Las ventajas serían la obtención de productos cerámicos con un alto valor añadido a partir de productos económicos, ya que sólo se actuaría sobre la superficie del vidriado, sin necesidad de que intervenga todo el espesor del mismo en los efectos decorativos o propiedades funcionales adquiridas. Cabe considerar desde efectos decorativos, como es el caso de los metalizados, lustres, etc, a nuevas propiedades funcionales: bactericida (basados en capas que contengan Ag) o fungicidas (capas de CuO).

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Figura 2

Figura 3. Micrografía de un vidriado con una capa nanométrica de CuO. Agradecimientos Los autores agradecen al Ministerio de Economía y Competitividad el apoyo recibido al desarrollo de la investigación (Plan Nacional de I+D, CTQ2011-28231) Referencias [1] J. M. Albella, “Láminas Delgadas y Recubrimiento. Preparación, propiedades y aplicaciones”. Madrid. Edit. CSIC. 2003.

[2] S.M. Pawar, B.S. Pawar, J.H. Kim, O.-S. Joo, C.D. Lokhande, “Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films”. Current Applied Physics 11 (2011) 117-161.

[3] P. S. Patil, “Versatility of chemical spray pyrolysis technique” Materials Chemistry and Physics 59 (1999) 185-198.

[4] C.Luyo, I.Fábregas, L. Reyes, J. L. Solís, J. Rodríguez, W. Estrada, R. J. Candal, “SnO2 thin-films prepared by a spray–gel pyrolysis: Influence of sol properties on film morphologies”. Thin Solid Films 516 (2007) 25–33.

[5] D.Wang, G. P. Bierwagen, “Sol–gel coatings on metals for corrosion protection”. Progress in Organic Coatings 64 (2009) 327–338.

[6] G. Korotcenkova, S. D. Han, “Cu, Fe, Co, or Ni)-doped tin dioxide films deposited by spray pyrolysis: Doping influence on thermal stability of the film structure”. Materials Chemistry and Physics 113 (2009) 756–763.

Variable-temperature IR spectroscopy for ranking Brønsted acidity

Montserrat Rodriguez Delgado*, Carlos Otero Arean Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca, Spain

*montserrat.rodriguez@uib.es 1. Introduction Solid acids having a large specific surface area, such as protonic zeolites and related porous solids, are often used as catalysts in a wide range of chemical processes, which span the petrochemical industry, methanol to olefin conversion and the production of fine chemicals, to quote some of the most common examples. The strength of their catalytically active Brønsted-acid sites is a main factor determining performance of such porous solids; hence the need of having a reliable method to rank surface acidity of solid acids.

However, at variance with aqueous acid solutions for which the corresponding pKa provides a quantitative measure of acid strength, no clear-cut measurement has yet been found for solid acids. The most common method currently being used relies on adsorption of a weak base (such as CO or dinitrogen) which forms hydrogen-bonded OH···CO (or OH···NN) adsorption complexes with the Brønsted-acid hydroxyl groups of the solid. The adsorption complex can easily be monitored by IR spectroscopy as hydrogen bonding brings about a distinctive bathochromic shift, Δν(OH), of the O−H stretching mode of the hydroxyl group. The magnitude of Δν(OH) (for any given weak base) is taken to be an indicator of relative Brønsted acidity when ranking solid acids [1]. The question, however, arises as to whether Δν(OH) really correlates with acid-base interaction energy or not. We report herein on recent studies showing that such a correlation cannot be taken for granted. 2. Methods and results Adsorption of CO and dinitrogen on several protonic zeolites belonging into different structural groups was studied by means of variable-temperature IR (VTIR) spectroscopy [2] (which affords simultaneous determination of Δν(OH) and standard adsorption enthalpy, ΔH0) and adsorption calorimetry. As an example, results obtained for CO adsorption on H-FER and H-MCM-22 (MWW structure type) are given in Figures 1 and 2. Corresponding results for other protonic zeolites (some of them taken from the published literature) are summarized in Table 1.

3000320034003600

-0,3

-0,2

-0,1

0,0

0,1

0,2

0,3

-2

0

2

4

4,0 4,5 5,0 5,5 6,0

98

76

5432

98765432

Abs

orba

nce

Wavenumber / cm-1

3605

1

1

A(OH) = -297 cm-1

H0 = -28,4 kJ mol-1

1000/T (K-1)

ln {

/[(1-)p

]}

3000310032003300340035003600

-0,2

-0,1

0,0

0,1

0,2

-4

-3

-2

-1

0

4,5 5,0 5,5 6,0

B

1110

1110

987654

32

9876

5

432

Abs

orba

nce

Wavenumber / cm-1

3625

1

1

(OH) = -320 cm-1

H0 = -22,5 kJ mol-1

ln {

/[(1-)p

]}

1000/T (K-1)

Fig. 1: (A) Representative variable-temperature IR spectra (O−H stretching region) of CO adsorbed on H-FER. From 1 to 9, temperature goes from 167 to 224 K; and equilibrium pressure from 0.57 to 1.75 mbar. (B) Representative variable-temperature IR spectra (O−H stretching region) of CO adsorbed on H-MCM-22. From 1 to 11, temperature goes from 154 to 214 K; and equilibrium pressure from 6.52 to 9.24 mbar. The spectra are shown in the difference mode (zeolite blank subtracted). Insets show the corresponding van’t Hoff plots.

Fig. 2: Adsorption heat of CO on H-FER (squares) and H-MCM-22 (circles) measured by calorimetry at 303 K, as a function of coverage. 3. Discussion and Conclusions Experimental results summarized in Table 1 clearly show that while for some protonic zeolites (H-Y, H-FER and H-ZSM-5) there is a direct correlation between standard adsorption enthalpy (ΔH0) and bathochromic shift (Δν(OH)) of the O−H stretching mode in the corresponding hydrogen-bonded (OH···CO) adsorption complex, the same does not hold in the case of other zeolites. Thus, MWW structure-type zeolites show a distinctively lower (absolute) value of ΔH0 (for CO adsorption) than H-FER and H-ZSM-5; and yet the (absolute) value of Δν(OH) (after hydrogen bonding with the probe molecule) is significantly larger for the protonic zeolites of the MWW group. Measurements performed by using dinitrogen as the probe molecule confirmed the results obtained with CO, in the sense that a direct correlation between Δν(OH) and ΔH0 was not always observed. Taken as a whole, the obtained results clearly show that the usual practice of ranking Brønsted-acid strength of solids by their O−H frequency shift probed by and adsorbed weak base can be misleading. Determination of the enthalpy change involved in formation of the corresponding hydrogen-bonded adsorption complex seems to be a more reliable instrumental method. References [1] E.A. Paukshtis, E.N. Yurchenko. Russ. Chem. Rev., 52, (1983), 242. [2] E. Garrone, C. Otero Arean. Chem. Soc. Rev., 34, (2005), 846. [3] C.O. Arean. J. Mol. Struct., 880, (2008), 31. [4] P. Nachtigall, O. Bludsky, L. Grajciar, D. Nachtigallova, M.R. Delgado, C.O. Arean. Phys. Chem. Chem.

Phys., 11, (2009), 791.

Table 1. Experimental data for CO hydrogen bonding in protonic zeolites.

Zeolite Structure type

-Δν(OH) (cm-1)

-ΔH0 (kJ mol-1) Ref.

H-Y FAU 275 25.6 [3]

H-ZSM-5 MFI 303 29.4 [3]

H-FER FER 297 28.4 [4]

H-MCM-22 MWW 320 22.5 This work

H-MCM-56 MWW 316 20 This work

0,00 0,05 0,10 0,15 0,200

5

10

15

20

25

30

H-FER H-MCM-22 first run H-MCM22 second run

Qdi

ff (kJ

mol

-1)

Coverage ()

Analysis of the growth conditions of nanoporous GaN particles by Chemical Vapor Deposition

J. Mena*, J.J. Carvajal, O. Bilousov, F. Díaz, M. Aguiló Física i Cristal•lografía de Materials i Nanomaterials (FiCMA-FiCNA) and EMaS, Universitat Rovira i Virgili (URV), Marcel•lí

Domingo, s/n, Tarragona, E-43007, Spain. *josue.mena@urv.cat

1. Introduction GaN is a promising material for optoelectronics applications but its big refractive index represents an important disadvantage for the development of LEDs [1]. The classical approach used to solve this problem has been the coverage of the material with a polymeric capsule with an intermediate refraction index [2]. An alternative solution to increase the light extraction efficiency of GaN based unencapsulated LEDs is the use of porous GaN [3]. The induced porosity in the material increases the reflection probabilities of emitted photons, and provides additional surfaces through which photons can escape. Based on the studies developed by ourselves [4] we use a non etching approximation to produce porous GaN using the direct reaction between metallic Ga and NH3 in a Chemical Vapor Deposition (CVD) system, in one single step without requiring any post-growth treatment to induce the porosity. In the present work we analyze morphologically and structurally the nanoporous GaN particles obtained by the direct reaction between Ga and NH3 in a CVD system by exploring the effect of different experimental conditions. The control of morphology, nanoporous density, and crystallographic orientation of the GaN particles are important parameters for advanced light emitting applications. 2. Results and discussion A set of experiments with three different shape holders for Ga were carried out to analyze how the shape of the crucible affected the spreading of the Ga droplet, and how this affected to the final shape and porosity of the particles obtained. The Ga holders used were a flat plate, a half cylindrical tube and a concave crucible. The GaN particles obtained when using a flat plate or a half cylindrical tube as Ga holders were similar, with sizes between 2-3 µm, and a similar degree of porosity. The particles obtained using the concave crucible show bigger sizes (around 4 µm), and the pores seem to be smaller in diameter and do not form ridges, giving a more rough aspect to the surface of the particles. Three sets of experiments were carried out with the introduction of different amounts of Ga at the beginning of the experiment (0.2 g, 0.4 g and 0.6 g), to analyze its effect on the coverage of the substrate with nanoporous GaN particles, while keeping constant the other reaction parameters. When 0.2 g of Ga were used, a low degree of substrate coverage was observed with a particle size around 5-6 µm. A higher coverage of nanoporous GaN particles could be seen when 0.4 g of Ga were used. In contrast with the previous case, the particle diameter was lower, of around 2µm. Finally, the GaN particles grown using 0.6 g of Ga had a similar particle density and size with the experiment using 0.4 g of Ga. This would indicate that it exist a quantity of Ga above which no more GaN particles are formed, probably related to the Ga/N ratio used. We performed additional experiments to analyze the influence of the deposition time in the shape and porosity of the GaN particles. The deposition times selected were 30, 45, 60 and 120 min. The tendency is to have a higher coverage of the substrate as we increase the time, but above a certain deposition time not only no more deposition was observed but decomposition of the previously formed particles was evident due to the high temperature and low vacuum conditions used in the experiments. To synthesize porous GaN on Si substrates, it is necessary to coat the substrate with a metallic catalyst [5]. Here, we tested different catalysts with which we coated (100) Si substrates: Ni, introduced as Ni(NO3)2 dissolved in ethanol, and 20 nm thick films of Ni, Au, Pt, and Ti deposited by RF sputtering. The bigger particles were obtained using Ni(NO3)2 as catalyst (see Figure 1(a)), while using Pt and Au we obtain smaller particles very homogenous in size. The highest level of porosity was obtained, however, in the GaN particles synthesized using Ni(NO3)2. Porous GaN particles grown on Ti thin films have a totally different morphology, remembering the shape of a sea star with a high level of porosity (see Figure 1(b)).

We have tested different substrates to ascertain if it might play a role in the crystallographic orientation of the GaN particles. For this purpose we used amorphous quartz, tungsten wire (W), (111) Silicon, and pyrolitic boron nitride (p-BN) as substrates. SEM images reveal that the substrate plays also a role in the coverage and distribution of the GaN particles.

Figure 1. Nanoporous GaN particles grown on (a) (100) Si substrate using Ni(NO3)2 as catalyst, (b) (100) Si substrate using 20nm of Ti as catalyst and (c) W wire substrate using Ni(NO3)2 as catalyst. 3. Conclusions We presented how different reaction parameters influence on the nanoporous Ga particles morphology, size and porosity degree. The Ga holder seems to have an influence on the earlier stages of evaporation and deposition of Ga on the substrate. The Ga quantity has an influence on coverage of the substrate with GaN particles. The deposition time also controls the coating of the substrate with nanoporous GaN particles. The catalyst plays two different roles: (1) it has an influence on the size of the initial nucleuses that can be formed, and (2) it might induce a texturation of the layer deposited. Finally, the substrate also plays an important role in the morphology and distribution of the nanoporous GaN particles on its surface, although the interlayer formed by the catalyst hampers the replication of the structure of the substrate by the porous GaN growing layer. 4. Acknowledgments This work was supported by the Spanish Government under projects No. MAT2011-29255-C02-02 and TEC2010-21574-C02-02, the Catalan Government under project No. 2009SGR235, and the European Commission within the Seventh Framework Program under project No. FP7-SPA-2010-263044. References [1] Kim,T.; Kim, S. H., Yang, S. S.; Son, J.K.; Lee, K.H.; Hong, Y.G.; Shim, K.H.; Yang, J.W.; Lim, K.Y.; Bae, S.J and Yang, G. M. “GaN based light-emitting diode with textured In tin oxide transparent layer coated with Al2O3 powder.” Appl. Phys. Lett. 94, (2009), 161107-1 – 161107-3 [2] Bao, K.; Kang, X. N.; Zhang, B; et al. “Improvement of light extraction from patterned polymer encapsulated GaN-based flip-chip light-emitting diodes by imprinting.“IEEE Photonics Technol. Lett., 19, 22, (2007), 1840-1842 [3] Wierer, J. J.; David, A. & Megens, M. M. “III- nitride photonic-crystal light-emitting diodes with high extraction efficiency.” Nat. Photonics., 3, 12, (2009),163-169 [4] Carvajal, J.J. and Rojo, J.C. “Morphology control in as-grown GaN nanoporous particles.” Cryst. Growth Des., 9, 1, (2009), 320-326 [5] Carvajal, J.J.; Bilousov, O. V.; Drouin, D.; Aguiló, M.; Díaz, F. & Rojo, J.C. “Chemical Vapor Deposition of porous GaN particles on Silicon.” Microsc. Microanal., 18, (2012), 905-911

Oral communication

White up-conversion emission in Er3+/Yb3+/Tm3+ doped YP5O14 ultraphosphate

M.A Hassairia, M. Dammaka, D. Zambonc,*, G.Chadeyron b,c, D. Boyer b,c and R.Mahiouc,d

(a)Faculté des Sciences de Sfax, département de Physique, BP 1171, Université de Sfax,3018 SFAX, Tunisie. (b) Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (c) Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (d) CNRS, UMR 6296, ICCF, BP 80026, F-63171 AUBIERE

* daniel.zambon@univ-bpclermont.fr

Trivalent lanthanides (Ln3+) doped materials exhibiting an efficient infrared into visible or ultraviolet light conversion are already very attractive for applications in up-conversion (UC) lasers, high-density memories, solid-state color displays, photonic devices and for biological or medical applications. The most investigated doping systems concerns Yb-Er, Yb-Tm and Yb-Er-Tm associations, mainly introduced in fluoride or oxide materials [1-5]. Moreover, a white up-conversion luminescence can be achieved from the association of Tm3+/Yb3+/Er3+ rare earth ions in inorganic lattices for peculiar optical applications e.g. liquid crystal display back light or white light LEDs [4]. In these tri-doped systems, the Yb3+ acts as the sensitizer ion because of its characteristic energy levels and its long 2F5/2 excited level lifetime. Er3+ is the optical activator that opens the possibility for simultaneous red and green emission transitions while Tm3+ is the origin of the blue emission. Despite their high phonon energy around 1000 cm-1, phosphates have attracted much attention as host lattices for Ln3+ ions because of a wide range of applications in optics and their unique physical and chemical properties. Concerning UC studies, most of the works concern Yb-Er, Yb-Tm or Yb-Er-Tm doped phosphate glasses or glass ceramics [6,7]. In this purpose, ultraphosphates with REP5O14 formula (RE = rare earth elements) have been raised the interest of the laser community, where REs elements are used as sensitizer-activator pairs for the up conversion phenomena. We have investigated the Tm3+/Yb3+/Er3+ tri-doped YP5O14 crystalline ultraphosphate in order to optimize the white emission via a UC mechanism using a 980 nm laser diode as excitation source. The ultraphosphate polycrystalline samples (monoclinic, S.G. C2/c) were synthesized by the solid state method. The doped materials were characterized by X-ray powder diffraction and infrared spectroscopy. In order to estimate the possibility of producing white emission, the IR → visible UC phenomenon under 980 nm excitation was studied at room temperature as a function of the Yb3+, Er3+ and Tm3+ concentrations. Red, green and blue UC emissions were simultaneously observed, due to the energy transfer from the Yb3+ 2F5/2 excited level to the main emitting levels of Er3+ and Tm3+. UC spectra revealed unambiguously the contribution of Er3+ emission transitions corresponding to 4F9/2 →4I15/2 (red region) and 2H11/2, 4S3/2 → 4I15/2 (green region) and Tm3+ emission transition corresponding to 1G4 → 3H6 (blue region), to generate white light. The influence of both excitation beam power and several doping ions amount on CIE chromaticity coordinates were analyzed. [1] Z.Y. Yan, B. Yan and L.P. Jia, Mater. Res. Bull., 48 (2013) 4402-4405. [2] S. Liu, G. Wang, K. Pan, Y. Li, L. Feng, C. Tian, B. Jiang, N. Fan, Q. Feng and J. Zhang, J. Fluorine Chem., 153 (2013) 61-67. [3] J.H. Chung, Y. H. Ryu, S.Y. Lee, S. H. Kang and K. B. Shim, Ceram. Inter., 39 (2013) 1951-1956. [4] X. Chen, Y. Li, F. Kong, L. Li, Q. Sun and F. Wang, J. Alloys Compds., 541 (2012) 505-509. [5] M. Marin-Dobrincic, E. Cantelar and F. Cusso, Opt. Mater. Express, 2(11) (2012) 1529-1537. [6] Y. Yu, F. Song, C. Ming, J. Liu, W. Li, Y. Liu and H. Zhao, Optics Com., 285 (2012) 4739-4744. [7] C. Ming, F. Song and X. Ren, Current Appl. Phys., 13 (2013) 351-354.

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FOTOCATALIZADORES CERÁMICOS DE TITANIA FOTOSENSIBLIZADOS CON METALES.

S. Cerro*, J. Badenes, C. Gargori, M. Llusar, G. Monrós, Dpto. Química Inorgànica y Orgànica, Universidad Jaume I, Castellón (España)

*cerro@uji.es 1. Introducción

Los Procesos de Oxidación Avanzada (POA) se basan en procesos fotoquímicos en los que el radical hidroxilo posee alta efectividad para la oxidación de contaminantes orgánicos, en disolución en agua o dispersados en el aire, resistentes a la degradación biológica a formas minerales o al menos a compuestos orgánicos inocuos. El óxido de titanio es la referencia como material fotocatalizador en la actualidad, dada su alta actividad, relativa estabilidad, bajo coste y baja toxicidad, sin embargo, hay problemas a resolver como la baja velocidad de fotocatálisis, generación de intermedios de degradación tóxicos, desactivación del material y necesidad de irradiación UV al no acoplarse su band gap con la luz solar [1]. La introducción de metales dopantes en el gel binario híbrido de Ti/Si ha sido estudiada con el fin de mejorar la capacidad fotocatalítica y obtener vidrios de alto índice de refracción para aplicaciones ópticas. Cerro y col. han aplicado vidriados cerámicos y composites cerámicos como fotocatalizadores, con interesantes resultados en la fotodegradación de substratos tales como Naranja II en disolución [2]. S. Satoh et al [3] estudiaron geles SiO2MOn/m (M = Ga,Gd, Nb, Sb, Sn, Ta, Ti y Zr) por métodos sol-gel, los resultados indican que son vidrios de interés potencial en aplicaciones ópticas. Asimismo, M. Baba y col [4] estudiaron la fotodegradación de colorantes orgánicos mediante vidrios de sílice dopados con metales de transición tales como Ti, V, Cr, Mn, Au y Ag, observando directamente nanopartículas de sílice dopadas con los complejos metálicos. Concluyen que el dopado con iones Au3+ es más eficiente que con Ag+. 2. EXPERIMENTAL Y RESULTADOS.

En este estudio se han utilizado como metales sensibilizadores los de la primera serie de transición Mn y Fe. El desarrollo de estos materiales se realiza mediante metodología sol-gel a partir de alcóxidos de titanio, acetato de hierro (II) y nitrato de manganeso (II) tetrahidrato. Los xerogeles obtenidos, son sometidos sucesivamente a un tratamiento de carbonización (300ºC/1h) y de estabilización(500ºC/1h) y caracterizados por diferentes técnicas: difracción de rayos X, indicando sólo la presencia de un halo amorfo de rutilo más intenso en el caso de Mn, análisis térmico diferencial y termogravimétrico (ATD-TG), espectroscopia UV-Vis-NIR, medida de la superficie específica BET, así como mediante el ensayo de fotodegradación de Naranja II [2]. 3. CONCLUSIONES.

Los resultados del ensayo de fotodegradación de naranja II indican un buen comportamiento de los geles de titania con un tiempo de semivida (t1/2 = 62 min) próximo a la anatasa de referencia. Las muestras sensibilizadas con hierro presentan valores ligeramente superiores a los xerogeles de titania y con capacidad fotocatalítica moderada-baja en el caso de manganeso. Ambos geles presentan alta superficie específica, ligeramente superior en el caso del Ti-Mn, con peores resultados fotocatalíticos. En el caso de las muestras carbonizadas a 300ºC/1h, ningún composite presenta actividad fotocatalítica con valores que superan los 200 min. En las muestras estabilizadas se observa un comportamiento moderado de fotoactividad, obteniéndose los mejores resultados para Ti y Ti-Mn con valores próximos a 130 min.

Referencias [1] C. Gargori, R.Galindo, M. Llusar, M.A. Tena, G. Monrós, J. A. Badenes, “Photocatalytic degradation of Orange II by titania addition to sol-gel glasses”. Journal of Sol-Gel Science and Technology, 50(2009)314-320. [2 S. Cerro, R.Galindo, A. García, A. Monrós, J. Badenes, C. Gargori, G. Monrós, , “Fotocatilazadores de y en cerámica”. Libro resúmenes Qualicer 2012. [3] S. Satoh, K. Susa, I. Matsuyama, “Sol-gel-derived binary silica glasses with high refractive index”. Journal of Non-Crystalline Solids, 146(1992)121-128.

Comunicación Oral

[4] M. Baba, M. Ichihara, R. A. Ganeev, M. Suzuki, H. Kuroda, M. Morita, D. Rau, T. Ishii, and M. Iwamura, “Direct observation of metal complex nanoparticles doped in sol-gel silica glasses using transmission electron microscopy”, Applied Physics Letters 84(2004)2394-2396. Agradecimientos: los autores agradecen la financiación de MEC (proyecto MAT2012-36988-C02-01)

"Synthesis of ceramic pigments by unconventional methods for novel ceramic

decoration technologies”

T. Stoyanova Lyubenova1, A. Rey1, D. Fraga, R. Martí1, I. Calvet, J. B. Carda1

1 Dept. Inorganic and Organic Chemistry, Jaume I University, Castellón, España

e-mail: stoyanov@uji.es

Nowadays, the ceramic tiles industry strongly promotes modernization and

implementation of new technologies in the ceramic decoration process. The necessity

to develop ceramic pigments with improved properties causes the search for more

effective and homogeneous synthesis methods than the traditional currently used

solid state route.

The main objective of this study is to describe the benefits of unconventional synthesis

processes like sol-gel, freeze and spray draying and spray pyrolysis for development of

ceramic pigments with properties according to the new trends and modern

decorations. In the same research line the “in –situ” photothermal laser activation is

also applied as thermal treatment alternative to the conventional furnace calcination.

For that purpose, pigments with sphene structure (Cr:CaTiSiO5 and Cr:CaSnSiO5) as a

hosts for Cr(III) cromophore were selected. The incorporation of Cr(III) results in solid

solution formation that develop shades ranging from magenta-pink to brown colors.

Thus, we have discovered a new pigment with Cr:CaTiSiO5 composition that had never

been used before for coloring ceramics.

The obtained materials were characterized structurally and microstructurally. The

chromatic behavior before and after direct application in reference glazes was

evaluated using UV-VIS spectroscopy and CIE Lab colorimetry.

References:

[1] Lyubenova, T.S., Matteucci, F., Costa, A., Dondi, M., Carda, J., Ceramic pigments with sphene structure obtained by both spray- and freeze-drying techniques, Powder Technology, 193 (1), pp. 1-5, (2009)

[2] Lyubenova, T.S., Matteucci, F., Costa, A.L., Dondi, M., Ocaña, M., Carda, J. Synthesis of Cr-doped CaTiSiO5 ceramic pigments by spray drying, Materials Research Bulletin, 44 (4), pp. 918-924, (2009)

[3] Cruciani, G., Dondi, M., Ardit, M., Lyubenova, T.S., Carda, J.B., Matteucci, F., Costa, A.L., Malayaite ceramic pigments: A combined optical spectroscopy and neutron/X-ray diffraction study, Materials Research Bulletin, 44 (8), pp. 1778-1785, (2009)

[4] Lyubenova, T.S., Ocaña, M., Carda, J., Brown ceramic pigments based on chromium (III)-doped titanite obtained by spray pyrolysis, Dyes and Pigments, 79 (3), pp. 265-269, (2008)

Órden alfabético | Classement par ordre alphabétique

PÓSTERSAFFICHES

www.efe-es.com

ABSTRACT BOOK

Póster

Aplicación de capas de óxidos mixtos de circonio sinterizadas por láser para incrementar las

propiedades mecánicas superficiales S. Enguidanos1, J.B. Carda2, R. Lahoz3, X. de la Fuente3, M.D. Notari1, *J. LLop1, I. Nebot Díaz1

1. Escola Superior de Ceràmica de l’Alcora

2. Dpto. Química Inorgánica y Orgánica, Universitat Jaume I, Castellón 3. Instituto de Ciencia de los Materiales de Aragón (ICMA.CSIC)

*jordi.llop@escal.es 1. Resumen

El presente trabajo, se fundamenta en la búsqueda de incrementar las propiedades mecánicas actuales del gres porcelánico. Estas propiedades, hacen que la utilización de este tipo de material sea idóneo en superficies de alto tránsito, si bien, sería deseable que presentaran unas mayores propiedades para mejorar su aplicabilidad y utilización. En la actualidad, las técnicas de laminados mediante materiales cerámicos para el incremento de las propiedades mecánicas de los materiales, vienen siendo utilizadas con asiduidad. El empleo de circonatos como cerámicas de alta tenacidad y resistencia está descrita en la bibliografía. El objetivo que se persigue en este trabajo, es la aplicación de laminados basados en circonatos sobre soporte de gres porcelánico tradicional, para incrementar sus propiedades mecánicas finales. Para ello, se utilizará la cocción mixta mediante radiación infrarroja y láser con el fin de alcanzar las temperaturas óptimas de síntesis de dichos circonatos.

Comunicación Póster

Borates and fluorides in exposed soils: effect of calcium carbonate.

N. Fas, S. Cerro, A. Monrós, C. Gargori, M. Llusar, G. Monrós, Dpto. Química Inorgànica y Orgànica, Universidad Jaume I, Castellón (España)

*nfas@uji.es 1. Introduction.

The emission of fluoride and borate pollutants is characteristic of the manufacture of tiles (due to clay degradation in tile firing at 1100-1200ºC) and glazes (due to condensation of borate vapors released from the frit kilns at 1400-1600ºC) [1]. The authors follow the presence of booth ions (borates and fluorides) since 2000 and differentiate between the kind of soil, such as calcarian soil (Onda-l'Alcora industrial parks) with a content in CaCO3 between 12-40 mgCaCO3/Kg or alluvial soils (Nules-Vila-Real industrial parks) with a content in CaCO3 between 3-9 mgCaCO3/Kg, in soils exposed to the emission of the ceramic industry of tiles and glazes in the ceramic cluster of Castellón (Spain). The fluoride is associated to tile industry and borate to ceramic glaze factories. The concentration of soluble borates depends of the rainfall which lixiviates it to underground waters. Instead, the presence of fluoride shows a relative accumulation in exposed soils due to calcium fixation as fluorite.

In this communication a study of the presence of both borates and fluorides ions in 2013 and compared with the historical evolution is presented. 2. Experimental and results.

Representative soil samples were collected in non-cultivated areas at a depth of 5 cm and were sifted by a sieve of 1 mm and air-dried for 72 hr. Aqueous extracts were analyzed by stirring for 20 min a mixture containing 20 g. air-dried soil and 100 mL distilled water This extraction method provides a measure of plant available boron and fluorine [2] in soil. The concentrations of boron were determined with a visible spectrophotometer (Azometine Method) [3]. Borate is fixed by organic matter and also by calcite sorption [4], thereby fluoride is fixed by calcium carbonate into insoluble compound as CaF2 [5], the plant available contents are considered a better indicator of boron and fluoride soil pollution. The collected soils were classified as T (Tile), G (Glaze) or T+G (Tile+Glaze) according to the prevalence of the type of factory in the environment. Four campaigns of analysis were carried out, in January 2013, April 2013, July 2013 and December 2013 (average rainfall in the last two months of 25.4, 71.6, 30.2, 5.2 L/m2 respectively from data of zone observatory network). Together to soluble boron and fluorides measurements, the 1:5 water extracts of soils were characterised by the measurement of conductivity, pH, hardness (equivalent ppm of CaCO3 by EDTA titration using Eriochrome Black T as indicator), nitrates (by ultraviolet spectrophotometry at 220 nm and sodium/potassium (flame spectrophotometry). The total carbonates as % of CaCO3 were also measured for several samples using the calcimeter of Bernard. All measurements were carried out three times. 3. Conclusions.

The obtained results confirm the “washing effect” for boron presence in the soils exposed to Tiles and Glazes industry in the analyzed industrial area, in agreement with literature. Thereby boron presence can be associated with glaze manufacture (G) and fluorine to tile manufacture (T), as described in literature. The diminution of tile manufacture (from 650 Mm2/year in 2000-2003 to 400 in 2013) and the increasing of porcelainised stoneware production explain the fluorine diminution detected, likewise the maintenance-increase on the glazes production associated to the implementation most accused of boron in the new lead free glazes and the introduction of boric acid as source of boron would explain the increase of boron presence in 2013 soils.

Comunicación Póster

References [1] R. Galindo, N. Fas, C. Gargori, S. Cerro, G. Monrós, Dynamics of fluoride and borate in soils exposed to the emission of the ceramic industry of tiles and glazes, 14th EuCheMs International Conference on Chemistry and the Environment, PS14, Barcelona 2013. [2] Aucejo A, Ferrer J, Gabaldón C, Marzal P, Seco P Diagnosis of boron, fluorine, lead, nickel and zinc toxicity in citrus plantations in Villarreal, Spain. Water, Air and Soil Pollution. 94(1997) 349-360. [3] Bingham, F. T. Boron, pp. 431-447 in A. L. Page (ed.) Methods of Soil Analysis. Part 2. Chemical and Microbiological Properties. American Society of Agronomy, Madison, WI. (1982). [4] Goldberg S, Forster HS Boron sorption on calcareous soils and reference calcites, Soil Science 152(4) (1991) 304-310. [5] Blagojević S, Jakovljević M and Radulović Mirjana Content of fluorine in soils in the vicinity of aluminium plant in Podgorica, Journal of Agricultural Sciences 47(2002)1-8. Acknowledgements: authors gratefully acknowledge the financial support of MEC (MAT2012-36988-C02-01 project).

Characterization of light–emitting diodes based on ordered InGaN nanocolumns

Almudena Torres-Pardo1,2,*, Ana Bengoechea-Encabo3, Steven Albert3, Miguel A. Sánchez-

García3, David López-Romero3, Zarko Gacevic3, Enrique Calleja3 and Jose M. González-Calbet1

1. Dept.Química Inorgánica, Facultad de Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain 2. CEI Campus Moncloa, UCM-UPM, Madrid, Spain

3. ISOM-Dept. Ingeniería Electrónica, ETSIT, Universida Politécnica, 28040 Madrid, Spain

*atorresp@ucm.es Group III-nitride semiconductors are widely used in opto-electronic devices. In particular, InGaN alloys are the active materials in light emitting diodes (LEDs) working in the whole visible spectrum. LEDs based on self-assembled nanocolumns (NCs) with InGaN/GaN disks constitute an alternative to conventional LED planar devices which major limitation is a strong reduction in efficiency at high current injection [1]. However, the efficiency and reliability of LEDs based on self-assembled NCs are hindered by a strong dispersion of electrical characteristics among individual nanoLED. Polychromatic emission derives from an inhomogeneous distribution of indium concentration, changes in the NCs geometry and the inherent tendency of InGaN alloys to develop composition fluctuations as a function of the polarity of the growth crystallographic planes [2]. The recent development of selective area growth of NCs by molecular beam epitaxy has allowed the achieving of highly homogeneous and controllable GaN/InGaN NCs with improved crystalline quality and higher control over the indium distribution [3,4]. In this work, we present results on the characterization of blue, green and yellow LEDs based on ordered NCs with InGaN active layers. The morphology and distribution of the NCs is assessed from Scanning and Transmission Electron Microscopy images (figure 1a-b) and their optical response is evaluated from the analysis of electroluminescence spectra. Structural characterization of the materials is performed by Scanning Transmission Electron Microscopy (STEM) carried out on aberration-corrected microscope [5]. The indium distribution and concentration of the InGaN disks is studied by EDS elemental maps confirming homogeneity of the InGaN layers. High crystal quality of the NCs is set by high-angle annular dark-field (HAADF) imaging, while the polarity determination of the semiconductor NCs is followed by locating the nitrogen atomic columns in annular bright field (ABF) images (figure 1c).

Figure 1(a) Cross-sectional SEM images of a representative sample. Inset shows top view SEM picture. (b) Low magnification TEM image of GaN/InGaN nanocolumn. (c) Atomically resolved Annular Bright Field (ABF) image

revealing the Ga and N atomic columns on the wurzite-type structure.

Acknowledgments J.M.G.C. and A.T.P. acknowledge financial support by the Spanish Ministerio de Ciencia e Innovación (MAT2011-23068 and CSD2009-00013) and facilities provided by the National Centre for Electron Microscopy (CNME, UCM, Spain). Research by A.T.P. has been also supported by a PICATA

postdoctoral fellowship of the Moncloa Campus of International Excellence (UCM). E.C, A.B.E, Z.G., M.A.S.G and D.L.R. acknowledge financial support by the EU FP7 Contract GECCO 280694-2, the EU ITN RAINBOW PITN-GA-2008-213238, and the Spanish projects CAM/P2009/ESP-1503 and MICINN MAT2011-26703. References [1] E. Kioupakis, P. Rinke, K. T. Delaney, C. G. Van de Walle, Appl. Phys. Lett. 98, (2011), 161107). [2] A. L. Bavencove, G. Tourbot, J. Garcia, Y. Desieres, P. Gilet, F. Levy, B. Andre, B. Gayral, B. Daudin, and

L. S. Dang, Nanotechnology,22, (2011), 345705. [3] S. Sekiguchi, K. Kishino, A. Kikuchi, Appl. Phys. Lett. 96, (2010), 231104. [4] S. Albert, A. Bengoechea-Encabo, M. A. Sanchez-Garcia, X. Kong, A. Trampert, E. Calleja, Nanotechnology

24, (2013), 175303. [5] Y. Li, L. Zhang, A. Torres-Pardo, J.M. González-Calbet, Y. Ma, P. Oleynikov, O.Terasaki, S. Asahina, M.

Shima, D. Cha, L. Zhao, K. Takanabe, J. Kubota, K. Domen, Nature Communications, 4, (2013), 2566.

Direct Laser Written Mid-Infrared Waveguides in Fused Silica and Crystalline Quartz

Javier Martínez1, Airán Ródenas1,*, Toney Fernandez3, Javier Rodríguez Vázquez de Aldana2, Javier Solis3 and Francesc Díaz1

1. Física i Cristal·lografia de Materials (FiCMA), Universitat Rovira i Virgili (URV), 43007, Tarragona, Spain 2. Grupo de Óptica, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca, Spain

3. Laser Processing Group, Instituto de Óptica-CSIC, Madrid 28006 Spain *airan.rodenas@urv.cat

1. Introduction Photonics, the science of light, has allowed a huge progress in a great variety of fields, such as telecommunications, sensing, laser manufacturing, medicine or information processing, among others. Most of the photonics devices have been based on visible and near-infrared (NIR) light, whose wavelength is lower than 2.5 µm. In recent years, however, there is an increasing interest in exploiting a range of longer wavelengths called the mid-infrared (MIR) range which spans from 2.5 to 20 µm. The MIR offers exciting advantages for applications in many scientific fields, apart from security and military areas. The MIR covers the “fingerprint” zone which enables the identification of greenhouse gases such as CO2 and CH4, or pollutants such as HCN and CF4. It is also the region where the Earth’s atmosphere exhibits important transmission windows for both Earth and space observation: the so-called L (3 - 4 µm), M (4.6 - 5 µm) and N (8 - 12 µm) bands. In order to unleash all this potential science, the development of MIR integrated devices which can be designed to operate as sensors, high resolution spectrometers or advanced beam combiners, is currently of high interest [1]. Femtosecond (fs) pulse direct laser writing (DLW) is a novel technique which has been demonstrated to be capable of producing three-dimensional (3D) waveguide designs and configurations which are required for efficient and low-loss interconnection between different components, such as optical fibers and waveguide chips [2]. In this work we explore the possibility of fabricating, with this technique, MIR waveguides in fused silica and crystalline quartz, which are transparent from the ultraviolet to up to the MIR at around 4 µm.

2. Experimental work 2.1. Femtosecond pulse laser 3D fabrication Low OH-concentration fused silica glass and standard α-quartz c-cut crystal, are employed as substrate materials for the waveguides. Fig. 1 shows examples of fabricated waveguides in crystalline quartz and fused silica. Although they have the same chemical composition (SiO2), their different molecular structure imposes a different interaction between the fs pulses and the material. Our presentation will show how we can create lowered refractive index structures in crystalline quartz, and increased refractive index structures in fused silica glass. In the case of the crystal, we have designed and fabricated cylindrical cladding structures which can sustain light propagation in the whole transparency range of the crystal. On the other hand, in fused silica the ultrashort pulses can induce a local increase of the index, from which we benefit to design step-index core waveguides which can guide light through bends and also feature low loss butt-coupling to commercial fibers.

Figure 1. Transmission microscope images of fabricated waveguides in (a) α-quartz crystal and (b) fused silica glass.

(a) (b)

Figure 2. Scheme of the optical setup used for modal characterization of NIR and MIR waveguides

2.2. Optical mid-infrared waveguide characterization We have built complete setup for NIR and MIR optical characterization of waveguides (see Fig. 2). Modal and propagation loss measurements of the waveguides are possible up to 5 µm, and spectroscopic characterization of waveguides transmission up to 12 µm with a fiber coupled FTIR spectrometer are also being performed. Some examples of modes measured at 3.39 µm wavelength in the MIR range are shown in Fig. 3. For α-quartz, two different types of cladding waveguides are shown: the first one is monomode (Fig. 3(a)) whereas the second one is much larger in size and supports a great number of modes (Fig. 3(b)). In the case of step index waveguides made in fused silica glass, we show here the observable modes for the waveguides shown in Fig.1b. Three different modes can be excited almost independently (see Figs. 3(c), 3(d) and 3(e), respectively).

Figure 3. Measured near-field intensity mode profiles for selected waveguides at 3.39 µm. (a) Monomode and (b) multimode waveguides made in α-quartz. (c), (d), (e) First three modes supported by a step-index waveguide made in fused silica.

3. Conclusions MIR waveguides embedded in glass and crystal are being developed by the femtosecond laser writing technique. Properties such as size, light confinement, modal behaviour or 3D propagation path can be easily controlled. An optical setup allows modal characterization of fabricated waveguides and testing of the performance providing feedback for fabrication optimization. The obtained waveguides will serve as MIR sensors and first results will be shown. 4. Acknowledgments This work has been partially supported by the Spanish Government under projects MAT2011-29255-C02-O2, by the Catalan Government under Project 2009SGR235 and 2014FI_B 00274 and by the European Commision under ACP2-GA-2013-314335- JEDI ACE. References [1] Airán Ródenas, Guillermo Martin, Brahim Arezki, Nickolas Psaila, Gin Jose, Animesh Jha, Lucas Labadie,

Pierre Kern, Ajoy Kar, and Robert Thomson, "Three-dimensional mid-infrared photonic circuits in chalcogenide glass," Opt. Lett. 37, 392-394 (2012)

[2] K. M. Davis, K. Miura, N. Sugimoto, and K. Hirao, "Writing waveguides in glass with a femtosecond laser," Opt. Lett. 21, 1729-1731 (1996)

(a) (b)

(c) (d) (e)

Efecto del tamaño en nanopartículas monodispersas de ferrita MFe2O4 (M=Fe, Co y Zn)

A. Delgado1, M. Virumbrales1, R. Sáez Puche1, y M.J. Torralvo1,* 1. Departamento de Química Inorgánica, Facultad Químicas, Universidad Complutense de Madrid, 28040, Madrid, España.

*torralvo@ucm.es Introducción

Las ferritas son óxidos mixtos AB2O4 (siendo A un metal divalente y B uno trivalente) que cristalizan con estructura tipo espinela, grupo espacial Fd-3m, dónde los cationes A2+ y B3+ ocupan 1/8 y 1/2 de los sitios tetraédricos (Td) y octaédricos [Oh] respectivamente, en un empaquetamiento cúbico compacto de O2-. La ferrita de Zn de tamaño micrométrico cristaliza con estructura de espinela normal, (Zn)[Fe2]O4, y como consecuencia de esta distribución catiónica es antiferromagnética con temperatura de orden, TN=10K. Por el contrario, las ferritas MFe2O4 con M= Fe y Co, son espinelas inversas, (Fe)[FeM]O4, y se comportan como ferromagnéticas con temperaturas de Curie de 848K and 793K respectivamente. Sin embargo, cuando estas ferritas espinela se preparan en la escala nanométrica, la distribución catiónica es de espinela mixta, donde los cationes M2+ y Fe3+ están ocupando simultáneamente los sitios Td y Oh dando como resultado una espinela de fórmula general (M1-xFex)[Fe2-xMx]O4, donde x es el grado de inversión [1]. Estos materiales presentan comportamiento superparamagnético por encima de la temperatura de bloqueo (TB) y sus propiedades magnéticas dependen del tamaño de partícula, del grado de inversión y de las interacciones entre partículas.

En la actualidad se han desarrollado numerosos métodos de preparación de nanopartículas con tamaño y forma controlados, pero en la mayoría de ellos se obtienen agregados de nanopartículas. Además del efecto en el comportamiento magnético, la agregación de las partículas constituye un gran problema para muchas aplicaciones tecnológicas por lo que se han investigado algunas rutas sintéticas alternativas, como por ejemplo, encapsular las nanopartículas en diferentes matrices orgánicas o inorgánicas para evitar o minimizar las interacciones entre las partículas. El presente trabajo se centra en el análisis comparativo de las propiedades morfológicas, estructurales y magnéticas de nanopartículas de ferrita, Fe3O4, CoFe2O4 y ZnFe2O4 estabilizadas con moléculas de ácido oleico con el fin de obtener nanopartículas aisladas y poder estudiar el efecto del tamaño en el comportamiento magnético, minimizando el efecto de las interacciones entre partículas.

Para la preparación de las nanopartículas de ferrita se ha seguido el método de descomposición térmica de precursores en disolventes de alto punto de ebullición [2]. Como precursores inorgánicos se han empleado los acetilacetonatos de Fe (III) y M (II), 1,2-hexadecanodiol como agente reductor, oleilamina y ácido oleico como agentes estabilizantes y feniléter como disolvente (BP: 259°C). Los reactivos se mezclan mediante agitación magnética bajo atmósfera inerte, se calienta la mezcla hasta 200°C y se mantienen un tiempo determinado y por último se calienta a reflujo. Con el fin de obtener nanopartículas de diferentes tamaños se han variado los tiempos de reacción. Conclusiones

Como se puede observar en las micrografías TEM (figura 1) las nanopartículas de ferrita MFe2O4 preparadas presentan, en todos los casos, morfología redondeada y una distribución estrecha de tamaños. El tamaño medio de las nanopartículas se ha estimado a partir de las micrografías midiendo entorno a 100 partículas, siendo de 4.7, 2.6 y 3.7 nm para las ferritas Fe3O4, CoFe2O4 y ZnFe2O4 respectivamente.

Los valores de susceptibilidad en todas las muestras son más altos que los que corresponden al comportamiento paramagnético lo que sugiere que en todos los casos las nanopartículas son superparamagnéticas por encima de la temperatura de bloqueo. A partir del máximo que se observa en la representación de las curvas de susceptibilidad ZFC frente a la temperatura, se han estimado las temperaturas de bloqueo de 6.35K, 53.6 K y 13.3K para las ferritas de Fe, Co y Zn respectivamente. El alto valor de TB que se observa en el caso de la espinela de cobalto, se debe a la anisotropía intrínseca del Co2+ en comparación con los cationes Fe2+ y Zn2+ [3]. La forma de las curvas FC y la gran diferencia entre los valores de susceptibilidad de las curvas ZFC y FC para

temperaturas inferiores a la de bloqueo, sugieren que las partículas no interaccionan o lo hacen débilmente debido a que están rodeadas de la envolvente orgánica.

Por otro lado, la magnetización es fuertemente dependiente de la interacción entre los cationes superficiales de la nanopartículas con las moléculas de ácido oleico. Mediante espectroscopía IR se ha determinado la naturaleza del enlace entre el ácido oleico y la superficie de las nanopartículas de MFe2O4. En el caso de la magnetita, los grupos carboxilato actúan como ligandos quelato lo que hace que aumente la anisotropía superficial y por tanto que disminuya la magnetización, y esto justificaría además que la temperatura de bloqueo sea solo de 6.3 K. Sin embargo, en la ferrita de zinc los grupos carboxilato, que actúan como ligandos puente, aumentan la magnetización. Esta ferrita presenta un momento magnético a la saturación anormalmente alto (figura 1c) con un valor de 80emu/g, que corresponde a un grado de inversión de 0.3. Por el contrario, en el caso de las espinelas de Fe y Co se observa una notable disminución de la magnetización a la saturación en comparación con sus homólogos de tamaño de partícula micrométrico.

Agradecimientos Los autores agradecen a la Comunidad de Madrid por el proyecto S-2009/PPQ-1626 y al MINECO por el proyecto MAT2010-19460. Referencias [1] V. Blanco-Gutierrez, F. Jimenez-Villacorta, P. Bonville, Maria J. Torralvo- Fernandez, R. Saez-Puche, J.

Phys. Chem. C, (2011) 115 (5) 1627–1634. [2] Shouheng Sun, Hao Zeng, David B. Robinson, Simone Raoux, Philip M. Rice, Shan X. Wang, and

Guanxiong Li, J. Am. Chem. Soc., (2004) 126 (1) 273-279 [3] V.Blanco-Gutierrez, J.A. Gallastegui, P. Bonville, M.J. Torralvo-Fernandez, R. Saez-Puche, J.Phys. Chem.

C, (2012) 116 (45) 24331

Fig. 1: Micrografías TEM de nanopartículas de espinela a) ZnFe2O4, b) CoFe2O4 y d) Fe3O4; c) Curvas de magnetización frente al campo aplicado a 5K para las diferentes muestras.

Poster o comunicación oral

Effect of the synthetic route on the crystal structure and physical properties of GdBaCo2O5+δ

Daniel Muñoz-Gil1*, Domingo Pérez-Coll2, Juan Peña-Martínez3, Susana Garcia-Martín1

1. Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, 28040-Madrid, España 2 Instituto de Cerámica y Vidrio, CSIC, Cantoblanco, 28049 Madrid, España

3. Departamento de Didáctica de las Ciencias Experimentales, Facultad de Educación, Universidad Complutense, 28040-Madrid, España

danimg@quim.ucm.es

Perovskite oxides represented by the general formula LnBaCo2O5+δ (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho) has drawn tremendous attention as potential cathodes for IT-SOFCs due to their electrical and electrochemical properties. In particularly, GdBaCo2O5+δ shows a wide range of oxygen non-stoichiometry and its attractive physical and structural properties depend on the oxygen content. The oxygen content of this oxide varies with the synthesis conditions. In this sense, GdBaCo2O5+δ with δ values close to 0 has been prepared in Ar atmosphere and δ values higher than 0.4 are always determined for samples prepared in air with a slow cooling or annealed in oxygen flow. The crystal structure of GdBaCo2O5+δ derives from the 112-type structure with ap × ap × 2ap unit cell (ap refers to the lattice parameter of the cubic perovskite) [1]. In this structure with δ = 0, Gd and Ba are ordered into layers along the c axis and all the Co atoms are coordinated by O in squared pyramids. The oxygen non-stoichiometry is accommodated within the (GdO)x planes in such a way that different supercells have been proposed in the literature depending on the oxygen content and the ordering of the anion vacancies (or the oxygen anions) in those planes [2-6].

Selected Area Electron Diffraction and High Resolution Transmission Electron Microscopy

have been used to reveal that the crystal structure and microstructure of GdBaCo2O5+δ are highly influenced by the oxygen stoichiometry. The electrical characterization includes total conductivity measurement by four point method under different atmospheres. The area-specific resistance (ASR) in air of GBCO as the electrode materials was measured by electrochemical impedance spectroscopy in a symmetrical two-electrode cell configuration.

We have observed that both oxygen stoichiometry and crystal structure have a high impact on

the physical properties of the material. In particular, significantly better electrochemical properties (lower ASR values), are observed for the material prepared under Ar gas flow, which shows the lower oxygen content (compared to the materials prepared at air) and the anion vacancies located at random. References

1. L. Er-Rakho, C. Michel, P. Lacorre and B. Raveau, J. Solid State Chem. 73 (1998) 531-535.

2. A. Maignan, C. Martin, D. Pelloquin, N. Nguyen and B. Raveau, J. Solid State Chem. 142 (1999)

247-260.

3. W. S. Kim, E. O. Chi, H. S. Choi, N. H. Hur, S. J. Oh and H. C. Ri, Solid State Comm. 116 (2000)

609-614.

4. Y. Moritomo, T. Akimoto, M. Takeo, A. Machida, E. Nishibori,, M. Takata, M. Sakata, K. Ohoyama,

and A. Nakamura, Phys. Rev. B. 61 (2000) R13325-R13328.

5. C. Frontera, J. L. García-Muñoz, A. Llobet, and M. A. G. Aranda, Phys. Rev. B. 65 (2002) 180405-

4(R).

6. A. A. Taskin, A. N. Lavrov and Y. Ando, Phys. Rev. B. 71 (2005) 134414

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Empleo de composiciones vítreas con titanio como elemento blanqueante para soportes de gres

porcelánico F. Ribes1, G. Rodríguez1, J. Llop*1, M.D. Notari1, J.V. Mundi1, I. Nebot Díaz1

1. Escola Superior de Ceràmica de l’Alcora

*jordi.llop@escal.es 1. Resumen

Mediante el presente trabajo, se pretende demostrar la viabilidad del empleo de fritas blancas de Titanio como agente blanqueante en pastas de gres porcelánico, y de esta forma poder minimizar el empleo de compuestos de Circonio para tal fin. Se ha desarrollado una frita blanca con Titanio, a la que se ha ajustado la composición para que tenga unas temperaturas características adecuadas a su utilización en composiciones de gres porcelánico. Las adiciones de diferentes proporciones de esta frita sobre una composición comercial de gres porcelánico sin aditivos de Zr, demuestra como se disminuye la temperatura de sinterización de la pasta, y se incrementa la blancura respecto a la composición inicial, sin una disminución de las propiedades técnicas del soporte.

Estudio de las interacciones magnéticas en nanopartículas de ZnFe2O4

M. Virumbrales1,*, A. Delgado1, R. Sáez Puche1 y M.J. Torralvo1 1. Departamento de Química Inorgánica, Facultad Químicas, Universidad Complutense de Madrid, 28040, Madrid, España.

*maider.virumbrales@ucm.es Introducción

Los materiales magnéticos nanoestructurados presentan inusuales propiedades químicas y físicas en comparación con sus análogos de mayor tamaño de partícula, lo que ha generado mucho interés debido a sus múltiples aplicaciones, tales como la tecnología de ferrofluídos, catálisis o aplicaciones médicas, como la liberación controlada de fármacos, agentes de contraste en resonancia magnética de imagen o en hipertermia [1].

En la escala nanométrica, las propiedades de las partículas dependen de los efectos de tamaño y

de los de efectos superficie, que aumentan según el tamaño de partícula disminuye. En nanopartículas magnéticas los efectos de tamaño están relacionados con el bajo número de portadores de momento ordenados, y los efectos de superficie se deben a la falta de coordinación, espines canteados y desorden de los átomos en la superficie. Por lo tanto, el comportamiento magnético de las nanopartículas es el resultado del núcleo ordenado y de la capa superficial desordenada. Las interacciones dipolares y de espines superficiales afectan el comportamiento magnético de las nanopartículas porque modifican la anisotropía del sistema. Por otra parte, las nanopartículas aisladas pueden interaccionar con el medio circundante [2] y estas interacciones también modifican la anisotropía de superficie y afectan a los parámetros magnéticos. La contribución y la fuerza de estas interacciones son diferentes dependiendo de la composición, tamaño de partícula y condiciones de síntesis y por lo tanto, puede ser difícil separar los efectos de tamaño y de superficie sobre las propiedades magnéticas. En este contexto, el objetivo de este trabajo es estudiar el comportamiento magnético de las nanopartículas de ferrita de zinc recubiertas con moléculas orgánicas y encapsuladas en matrices porosas de sílice con el fin de investigar el efecto de las interacciones de las nanopartículas sobre las propiedades magnéticas.

Para la preparación de las nanopartículas de ZnFe2O4 se han empleado dos métodos de síntesis. En el primero de ellos, se ha seguido un método basado en la descomposición térmica de los precursores de la ferrita en disolventes de alto punto de ebullición [3]. Como precursores de la ferrita se han empleado Zn(acac)2 y Fe(acac)3 y fenil éter como disolvente. Además, para proteger la superficie de las nanopartículas y controlar su crecimiento, se han utilizado como agentes estabilizantes oleilamina, ácido oleico y 1,2-hexadecanodiol como agente reductor (figura 1a, muestra Zn-3.7). En el segundo método se ha infiltrado por capilaridad una disolución acuosa con cantidades estequiométricas de nitrato de zinc y nitrato de hierro en matrices porosas previamente preparadas, con estructura tipo MCM-41 (figura 1b, muestra MH-Zn) y SBA-15 (figura 1c, muestra SB-Zn). Los materiales infiltrados se mantienen al aire durante 24 horas y posteriormente se someten a 600°C durante 2 horas. Después de este tratamiento térmico se obtienen nanopartículas de ZnFe2O4 encapsuladas en las matrices. Conclusiones

En la micrografía TEM correspondiente a las nanopartículas de ferrita de zinc estabilizadas con ácido oleico (figura 1a), se pueden observar nanopartículas con tamaño y forma homogéneo, que presentan un distribución estrecha de tamaños centrada en 3.7 nm. En las figuras 1b y 1c se muestran imágenes de las muestras correspondientes a las nanopartículas de ZnFe2O4 encapsuladas en las matrices porosas de sílice. Las nanopartículas de ferrita tienen tamaños de partícula de aproximadamente 2.5 nm en la matriz MCM-41 y 6-9 nm en la matriz SBA-15, de manera que ocupan prácticamente todo el ancho del canal de la matriz.

A partir del máximo en las curvas de susceptibilidad ZFC (figura 1d) se han estimado los valores

de temperatura de bloqueo (TB), que aumentan al aumentar el tamaño de las partículas. Los altos valores de susceptibilidad sugieren, en todos los casos, comportamiento superparamagnético por encima de la temperatura de bloqueo. La forma de la curva de susceptibilidad FC y la gran diferencia

entre las curvas ZFC y FC a bajas temperaturas sugieren que las interacciones entre partículas no son significativas. En el caso de las nanopartículas de ferrita de zinc estabilizadas con ácido oleico, se comportan magnéticamente independientes sin interacciones. Aunque puedan existir interacciones dipolares debido a la envolvente orgánica estas interacciones no son suficientemente intensas como para impedir el aumento de magnetización por debajo la TB. Las nanopartículas de ZnFe2O4 encapsuladas en las matrices porosas de sílice son fuertemente magnetizadas a baja temperatura aunque están alineadas en el interior de los poros de la matriz y por lo tanto, deben presentar interacciones dipolares. Por la geometría de los canales, aunque las partículas interaccionen no pueden formar estados de espines desordenados magnéticamente congelados que puedan impedir la magnetización a baja temperatura.

Por otro lado, los valores de campo coercitivo a 5K son mayores en el caso de las nanopartículas

de ferrita de zinc encapsulada en las matrices porosas en comparación con las nanopartículas de ZnFe2O4 estabilizadas con ácido oleico, lo que se ha atribuido a la tensión mecánica impuesta por la matriz [4].

Agradecimientos Los autores agradecen a la Comunidad de Madrid por el proyecto S-2009/PPQ-1626 y al MINECO por el proyecto MAT2010-19460. Referencias [1] Y.W. Jun, J.W. Seo, J. Cheon, Acc. Chem. Res., (2008) 41 (2) 179-189 [2] V. Blanco-Gutierrez, M. Virumbrales, R. Saez-Puche, and Maria J. Torralvo-Fernandez, J. Phys. Chem. C,

(2013), 117 (40), pp 20927–20935 [3] S. Sun, H. Zeng, D. B. Robinson, S. Raoux, P. M. Rice, S. X. Wang, and G. Li, J. Am. Chem. Soc., (2004)

126 (1) 273-279 [4] - - - -Puche, Chem. Mater.,

(2010) 22 (22) 6130–6137

Figura 1. Micrografías TEM de: (a) nanopartículas de ZnFe2O4 estabilizadas con ácido oleico (muestra Zn-3.7) y encapsuladas en matrices tipo (b) MCM-41 (muestra MH-Zn) y (c) SBA-15 (muestra SB-Zn). (d) Curvas de susceptibilidad magnética ZFC/FC para las distintas muestras.

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High reflective ceramic tiles from tenorite glazes and silver-titania sol-gel films over glazes.

S. Cerro, N. Fas, C. Gargori, M. Llusar, G. Monrós, Dpto. Química Inorgànica y Orgànica, Universidad Jaume I, Castellón (España)

*cerro@uji.es 1. Introduction.

The reflectivity of a surface is the fraction of light reflected and can be calculated from the refractive index at the normal incidence angle through the Fresnel equation [1]:

2

1n1-nR

(eq. 1) The reflection of light in an interface between two media of different refractive index shows a

different dispersion depending on the incidence angle generated between the incidence direction rays and the normal direction to surface. The bright in direction is done by:

AI

B

(eq. 2) where B is the bright on direction , and I and A are the reflected intensity and the elemental area in the direction respectively. If the dispersion follows the cosine law (eq. 3), the reflection is called diffuse reflection:

cosII 0 (eq. 3) where Io is the dispersed intensity at =0. Thus the bright in a given direction is constant:

constant

AI

cosAcosI

Bo

o

o

o

(eq. 4) If the dispersion is 0 in any direction except in the reflected direction =i where i is the incidence angle of light rays, the reflection is a specular reflection. The specular reflection is related to high smooth surfaces and diffuse reflection to roughness surfaces.

Glazes with a metallic appearance can be obtained classically from the crystallization of high

refractive phases such as Fe2Fe(P2O7)2 iron (III) iron (II) pyrophosphate or noble metals (Ag, Hg, Cu) in the form of glossy preparations, preparations for burnishing, such as lacquers or pastes, or powdered substances [2,3]. In this study high reflective coatings over porcelainised stoneware ceramic tiles for solar collection have been prepared and characterized from glazes which crystallize tenorite (CuO monoclinic, PG 2/m, SG C2/c, n=2.63) using a conventional thermal treatment of porcelainised stoneware (1200ºC) used as black pigment [4] or from precipitation from polyglicol and acetylacetonate complexes of metallic cations introduced as titanium n-butoxide and silver nitrate, working in oxidising atmosphere at 400ºC [3], the high refractive index of oxides (n=2.7 for anatase TiO2) and low roughness of deposited layer give high reflective surfaces. 2. Experimental and results.

The glaze which crystallizes tenorite was obtained by addition CuO and other modifiers such as TiO2 anatase and MnO2 to conventional frits for porcelainised stoneware (with lead addition or without lead addition using bismuth as ecofriendly substitute). The mixture was milled in water media and the slurry was deposited by a doctor blade procedure. The glazed tile was fired at 1200ºC using a conventional porcelainised stoneware thermal cycle. As it has been indicated above, silver-titania composites has been deposited by screen printing (90 threads/cm) over glazed and fired porcelainised stoneware tiles from polyglicol (diethylenglycol 40 g) and acetylacetonate (molar ratio acac:Ti=1:1) stabilized inks of titanium alkoxides (isopropoxide ISTi or n-butoxide NBTi) and silver nitrate, fired in oxidising atmosphere at 400ºC/1h. In order to measure roughness of the surfaces it is used a skidless pickup SM3 equipment that gives the average of deviations from the line base Ra (roughness average) in a run of 5-10 cm of the pin over the surface. Both diffuse and specular reflectivity is measured using

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a X Rite serie SP60 using illuminant D65 and observer 10º. The resulting bright of a surface is the joint of two factors: high refraction index of the material, indeed high reflectivity, and low roughness of the surface. The thermal depositions of fine coatings of metal oxides give smooth surfaces of high refractive index that produces luster effects.

In Figure 1 are described some samples characterized by its optical and SEM photography, its specular reflectivity Rsp front the wavelength of light (higher at high for Silver-Titania coatings and at low for tenorite glazes), its X ray diffraction (showing tenorite crystallizations in Cu-glazes, more intense in bismuth glaze, and cristobalite SiO2 (from the above glaze), silver metal and anatase in silver-titania films), its L*a*b* colorimetric parameters and the Ra (roughness average) around 1 m for all samples.

Fig. 1: results obtained in the indicated samples. 3. Conclusions.

Reflective coatings (specular reflectance around 30 and 40%) over porcelainised stoneware ceramic tiles for solar collection have been prepared and characterized from glazes which crystallize tenorite (CuO) using a conventional thermal treatment of porcelainised stoneware (1200ºC) and from precipitation from polyglicol and acetylacetonate complexes of metallic cations introduced as titanium alkoxides and silver nitrate by screen printing over fired glazed tiles, working in oxidising atmosphere at 400ºC. The high refractive index of tenorite (n=2.63 at λ=589 nm) and anatase (n=2.7 λ=589 nm) and low roughness of deposited layer give high reflective surfaces.

References [1] Wooten, Frederick (1972). Optical Properties of Solids. New York City: Academic Press. [2] M.J. Cabrera, V. Montíns, A. Foó, P. Balfagón, “Obtainment of glazes with a metallic appearance in single-fired tiles, Qualicer 2006, P.BC 253-254 [3] C. S. Ray, X. Fang, M. Karabulut, G. K. Marasinghe and D. E, Day, “Effect of Melting Temperature and Time on Iron Valence and Crystallization of Iron Phosphate Glasses,” Journal of Non-Crystalline Solids,249,1 (1999) 1-16. [4] L. Burgio, R. J. H. Clarkk, R. R. Hark, Raman microscopy and x-ray fluorescence analysis of pigments on medieval and Renaissance Italian manuscript cuttings”, Proceedings of the National Academy of Sciences of the United State of America, 107,13,( 5726–5731). Acknowledgements: authors gratefully acknowledge the financial support of MEC (MAT2012-36988-C02-01 project) and CDTI-Torrecid (10I076 Project).

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In situ and classical Karrooite ceramic pigments obtained by MOD and Sol-Gel methods.

S. Cerro, N. Fas, C. Gargori, M. Llusar, G. Monrós, Dpto. Química Inorgànica y Orgànica, Universidad Jaume I, Castellón (España)

*cerro@uji.es 1. Introduction. Karrooite belongs to pseudobrookite structural family (Fe2TiO5) which provides the type structure (space group 63, Cmcm) for a chemically wide-ranging group of both mineral and synthetic metal oxides with the general formula AB2O5. Its crystal structure consists of edge-shared MO6 octahedra, with two non-equivalent octahedral sites, M1 (4c) and M2 (8f), occurring in the ratio 1:2, the M1 site is larger and more distorted than the M2 site. Pseudobrookite-type minerals have been found in volcanic and in highly oxidized metamorphic rocks, and were identified in lunar basalts formed from Ti-rich, reduced magmas. Armalcolite, Fe0.5Mg0.5Ti2O5, the pseudobrookite structured lunar mineral, was named for the first lunar explorers, and Mg-rich Karroo volcanics in South Eastern Zimbabweand South Africa have provided members of the solid solution MgTi2O5.Fe2TiO5 [1].

Karrooite, MgTi2O5, is a promising ceramic pigment due to its high refractoriness and refractive indices, as well as its ability to host transition metal ions in two crystallographically distinct octahedral sites. F.Matteucci et al. study the colouring performance combining X-ray powder diffraction with UV–Vis–NIR spectroscopy on karrooite doped with V, Cr, Mn, Fe, Co or Ni (M) according to the formula Mg1−xTi2−xM2xO5, with x=0.02 and 0.05. Transition metals solubility in the karrooite lattice is not complete and a second phase is always present (geikielite or rutile). Structural data proved that incorporation of different chromophore ions into the karrooite structure affects unit cell parameters, bond length distances and angles, site occupancies and therefore cation order–disorder. Optical spectra exhibit broad absorbance bands of Co(II), Cr(IV), Fe(III), Mn(II), Mn(III), Ni(II), V(IV) with distinct contributions by cations in the M1 and M2 sites. Karrooite pigments have colours ranging from orange to brown-tan (Cr, Fe, Mn, V) to green (Co) and yellow (Ni) that are stable in low-temperature (<1050 °C) ceramic glazes and glassy coatings [2].

In this communication the synthesis of Mg(MxTi2-x)O5 M=Cr,V karrooite pink and blue ceramic pigments by MOD (Metal Organic Decomposition) methods using citric acid as polycarboxylic chelate agent and a Sol-Gel method are presented. Samples with x=0.1 (Cr) and x=0.2 (V) were synthesized by CE (ceramic), CO (conventional coprecipitation method with ammonia), MOD ( metal-organic decomposition of chelates with addition of Citric acid:Karrooite=0.5:1 molar ratio) and GP (a sol-gel from titanium n-butoxide with hydrolisis time of 1 day, 3 days and 7 days). In situ pigments from direct suspensions obtained and from mixtures DEG: powder fired at 500ºC=1:5 deposited by screen printing over a withe fired porcelanised stoneware tile. 2. Experimental and results.

In the CE method oxides and carbonates were milled in acetone media. In CO, MOD and GP Cr(NO3)3 9H2O, Mg(NO3)36H2O and titanium n-butoxide were used as precursors and coprecipitated by ammonia addition to the aqueous media in CO method, chelated with citric acid and gelled with ammonia addition in the aqueous media in MOD synthesis and hydrolyzed in ethanol media in the GP method. The gels were dried at 110ºC and fired at 500ºC all samples and posteriorly to 1000 and 1200 ºC for Cr and V samples respectively. Samples were 5% glazed in a conventional tile glaze (1050ºC)

The samples have been characterized by colorimetric CIEL*a*b* measurements (illuminant D65 and observer 10º), XRD and UV-Vis-NIR optical spectra. 3. Conclusions.

In situ inks from direct suspensions give pink shades in Cr-Karrooite (L*a*b*=56.3/10.7/16.3 for CO sample) and orange in V-Karrooite (71.6/9.2/25.3 in CO sample). In situ inks obtained from mixtures DEG: powder fired at 500ºC=1:5 produces yellow-green shades (73,7/3,4/19,9 in CO sample) and orange-brown in V-Karrooite (70.4/9.5/24.0 in GP-3 days sample). The use of powders fired at 500ºC produce interesting pink shades with GP method (59,6/11,7/14,5 in GP-1 day) in Cr-Karrooite samples but are colorless in V-Karrooite samples. All unconventional samples show

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Karrooite crystallization at only 500ºC. In all samples fired at 1000 or 1200ºC Karrooite crystallize with high intensity XRD peaks but always residual peaks of rutile are detected. From 1000-1200ºC fired samples shades from orange (e.g. L*a*b*=64.6/11.2/26.0 in CE sample fired at 1000ºC) to pink. (e.g. L*a*b*=60.5/8.5/13.3 in CO sample fired at 1000ºC) have been obtained by Cr doped Karrooite and blue shades (e.g. L*a*b*=55.2/3.2/-8.0 in GP-3 days sample fired at 1200ºC). In the case of Cr-Karrooite both Cr4+ and Cr3+ in octahedral site can be detected by UV-Vis-NIR spectra, the intensity of bands for Cr4+

is higher in the orange shades and the bands associated to Cr3+ in the pink shades. Bands of Cr3+ are detected at higher than in the literature for Cr-alumina [3]. In the case of V-Karrooite the blue shades can be associated to V4+ [4].

Fig. 1: XRD of unconventional samples Cr-Karrooite fired at 500ºC/1h showing the crystallization of Karrooite and SEM micrograph of Cr-Karrooite GP 1 day fired at 1000ºC/3h.

References [1] A.R. Lennie, K.S. Knight, C. Michael, B. Henderson, Cation ordering in MgTi2O5 (karrooite): Probing temperature dependent effects with neutrons, American Mineralogist, 92(2007)1165.1180. [2] F.Matteucci, G. Cruciani, M. Dondi, G. Gasparotto, D.M. Tobaldi, Crystal structure, optical properties and colouring performance of karrooite MgTi2O5 ceramic pigments, Journal of Solid State Chemistry 180,11(2007)3196-3210. [3] Ceramic pigments based on chromium doped alkaline earth titanates, A. García, R. Galindo, C. Gargori, S. Cerro, M. Llusar, G. Monrós, Ceramics International 39 (2013) 4125–4132 [4] J.B. Vicent, J. Badenes, M. Llusar, M.A. Tena, G. Monros, Differentiation between the Green and Turkish Blue Solid Solutionsof Vanadium in a Zircon Lattice Obtained by the Sol-Gel Process, Journal of Sol-Gel Science and Technology 13 (1998) 347–352 (1998). Acknowledgements: authors gratefully acknowledge the financial support of of MEC (MAT2012-36988-C02-01 project.

Póster

Influencia del dopaje con lantano o gadolinio en cerámicas basadas en BNT-BT

Elena Cerdeiras 1,*, Rodrigo Machado 2, Diego A. Ochoa 2, José E. García 2, Lourdes Mestres 1 1. Departament de Química Inorgànica, Universitat de Barcelona, 08028, Barcelona, España

2. Department of Applied Physics, Universitat Politècnica de Catalunya, 08034, Barcelona, España *elena.cerdeiras@ub.edu

Las cerámicas ferroeléctricas presentan unas características insuperables como materiales piezoeléctricos en la gran mayoría de aplicaciones. Entre estos materiales, el más destacado es actualmente el titanato circonato de plomo (PZT). Estas cerámicas piezoeléctricas con estructura perovskita son ampliamente utilizadas como actuadores, resonadores y otros dispositivos electromecánicos debido a sus excelentes propiedades piezoeléctricas [1]. Sin embargo, la mayor desventaja que presentan es la elevada toxicidad del plomo. El uso y fabricación de materiales que contienen este elemento han causado serios problemas medioambientales y para la salud humana. Como consecuencia, en el 2003, la Unión Europea consideró el PZT como sustancia peligrosa [2,3]. Por esta razón, el objetivo de la comunidad científica durante la última década ha sido la búsqueda de nuevos materiales piezoeléctricos libres de plomo susceptibles a sustituir al PZT. Actualmente, las investigaciones se centran en cerámicas que presentan una transición de fase morfotrópica (MPB) similar a la del PZT. En este sentido, el sistema formado por el titanato de bismuto y sodio, Bi0,5Na0,5TiO3 (BNT), y el titanato de bario BaTiO3 (BT), ha suscitado un notable interés durante los últimos años desde el descubrimiento de la presencia de una MPB en 1991. Según el diagrama de fases, el sistema (1-x) BNT – x BT presenta una MPB entre una fase romboédrica y una tetragonal a temperatura ambiente para una composición cercana a x = 0,06 donde se obtienen unas buenas propiedades piezoeléctricas [5]. A fin de mejorar las propiedades funcionales de estos sistemas, una de las estrategias comúnmente utilizadas es la modificación de la composición a través de la incorporación de dopantes en la red cristalina. Las vacantes catiónicas, creadas a partir de la sustitución por iones de mayor carga en las posiciones A de la perovskita, provocan una mayor distorsión de los octaedros favoreciendo la creación de dipolos y asimismo una modificación de las propiedades del material. Se han utilizado diversos tipos de cationes en sustitución de los iones presentes, con la intención de modificar las propiedades del BNT-BT [6]. Los lantánidos son a menudo utilizados como elementos dopantes en el sistema BNT-BT a fin de mejorar las propiedades piezoeléctricas y ferroeléctricas de las cerámicas [7-8]. En consecuencia, el objetivo principal de este trabajo es el estudio de la influencia del lantano o el gadolinio en las propiedades funcionales y la microestructura de cerámicas basadas en el BNT-BT. Los materiales (1-x) Bi0,5Na0,5TiO3 – x (Ba1-yLn2y/3)TiO3 (BNT-BLnT), siendo x = 0,06; y = 0,30; Ln = lantano y gadolinio, se prepararon mediante reacción en estado sólido. Fue analizada la evolución del sistema mediante las técnicas habituales en química del estado sólido: difracción de rayos X, espectroscopia Raman, microscopia electrónica de barrido y espectroscopia de dispersión de energía de rayos X. Todas las cerámicas presentan una única fase con estructura perovskita confirmando la formación de un sistema estable entre el BNT y el BLnT. Con la finalidad de analizar si la sustitución por iones trivalentes es una forma prometedora de mejorar las propiedades de piezocerámicas basadas en el BNT-BT y si el tamaño del dopante influye en la modificación de éstas se evaluaron las propiedades eléctricas de las cerámicas obtenidas. Agradecimientos Este trabajo ha sido parcialmente financiado por el proyecto MAT2010-21088-C03-02 del MCI y el proyecto SGR2009-0674 de la Generalitat de Catalunya.

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Referencias [1] B. Jaffe, W. R. Cook, H. Jaffe, “Piezoelectric ceramics”. Academic Press: London, New York, (1971). [2] EU-Directive 2002/95/EC: Restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS). Official J. European Union, 46, L37, (2003), 19-23. [3] EU-Directive 2002/96/EC: Waste electrical and electronic equipment (WEEE). Official Journal of the European Union, 46, L37, (2003), 24-38. [4] J. Rödel, W. Jo, K. T. P. Seifert, E. M. Anton, T. Granzow, D. Damjanovic, “Perspective on the Development of Lead‐free Piezoceramics”. Journal of the American Ceramic Society, 92, (2009), 1153-1117. [5] T. Takenaka, K. Maruyama, K. Sakata, “(Bi1/2Na1/2)TiO3-BaTiO3 System for Lead-Free Piezoelectric Ceramics”. Japanese Journal of Applied Physics, 30, (1991), 2236-2239. [6] H. D. Li, C. D. Feng, W. L. Yao, “Some effects of different additives on dielectric and piezoelectric properties of (Bi1/2Na1/2)TiO3–BaTiO3 morphotropic-phase-boundary composition”. Materials Letters, 58, (2004), 1194-1198. [7] C. Zhi-hui, D. Jian-ning, M. Lin, Y. Ning-yi, Z. Yuan-yuan, “Piezoelectric and dielectric properties of Dy2O3-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics”. Journal of Alloys and Compounds, 509, (2011), 482-485. [8] Q. Li, H. Wang, H. Fan, C. Long, X. Liu, “Ferroelectric, electromechanical, and dielectric properties of (Na0.5Bi0.5)0.94Ba0.06TiO3 co-doped MnO2 and La2O3 lead-free ceramics”. Journal of Materials Science, 49, (2014), 211-217.

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Laminate low cost chalcogenide photovoltaic technology based on ceramic and glass substrates

Diego Fraga1,*, Rafael Martí1, Iván Calvet1, Aitor Rey1, Ester Barrachina1, Teodora Stoyanova1

and Juan B. Carda1 1. Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón

*fraga@uji.es 1. Introduction The Solid State Chemistry group (UJI) have dedicated it efforts during the last years on development of calchogenide thin film solar cell on different ceramic tiles substrate for photovoltaic architectural integration that playing energy function and serves as further constructive elements. The topic is based on the project belonging to INNPACTO Program: “Laminate low cost chalcogenide photovoltaic technology based on ceramic and glass substrates” IPT-2011-0913-920000 (2011-2013) supported by the Spanish Ministry of Economy and Competitiveness. The project has three main components: i) substrates selection, preparation and optimization; ii) back contact deposition and iii) synthesis and deposition of chalcogenide semiconductors as absorber layers by chemical- based low cost routes. For solar cell support ceramic porcelain stoneware tile, tile with recycled-glass and glass-ceramics were tested. As a back electrical contact molybdenum and conductive glazes were prepared and further deposited. The main group activity related with the third project task is the synthesis of Cu(In1-xGax)Se2 (CIGS) by chemical methods as solvothermal, coprecipitation, sol-gel and hot-injection and it and deposition onto the substrates using Spin coating and Doctor Blade techniques. In the same approach, the group has also obtained interesting results with kesterites Cu2ZnSn(S,Se)4 (CZTS,Se) structure as an alternative to CIGS absorber material. Acknowledgment This work has been achieved through the collaboration of Invest Plasma, Torrecid Group and Spanish Ministry of Economy and Competitiveness

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Material vítreo reciclado para difusión de luz de led’s Vicente Faubel1, Francisco Pardo1, Teofilo Sanfeliu1

1. Unidad de Mineralogía Aplicada y Ambiental. Universitat Jaume I. Castellón INTRODUCCIÓN Existe una preocupación por parte de las administraciones públicas por la inclusión y desarrollo de nuevos productos con materiales reciclados (RCD)[1]. De hecho los objetivos cuantitativos del II PNRCD para 2015 son del 40% de reciclaje y un 70% de valorización de los residuos de materiales de construcción.[2] La fabricación de mosaicos vítreos se ha basado en la producción de piezas en forma monolítica, de distintas dimensiones, texturas y colores pero siempre semi-opaco [3]. El proceso productivo parte de un residuo como materia primera básica, el vidrio reciclado, para obtener mosaico vítreo. Se excluye el vidrio de envases, por contener materia orgánica que reduce la calidad del producto. El vidrio de cristalera hubiera facilitado el proceso, por ser altamente transparente, pero su alto contenido en plomo y cadmio, transgredía con uno de los objetivos principales del proyecto, ser ecológico. Se selecciona el vidrio float, cuya composición es más estable y ecológica.

1. OBJETIVOS El objetivo principal de este estudio es el desarrollo de nuevos productos para integrar la tecnología Led’s (Light Emitting Diode) en los mosaicos vítreos por prensado, dotando así de un mayor valor añadido al nuevo producto y creando un concepto nuevo de eficiencia energética.

2. DESARROLLO El vidrio es un material duro, frágil y transparente obtenido por fusión a unos 1.500 ºC de compuestos vitrificantes, arena de sílice (SiO2), fundentes, carbonato sódico (Na2CO3), y estabilizantes, caliza (CaCO3).[4]. En un vidrio, los enlaces Si-O-Si no tienen una orientación determinada; la distancia de separación entre los átomos de Si y O no es homogénea, las unidades tetraédricas no se repiten con regularidad y el compuesto está desordenado, sílice amorfa.[5]. El contenido en partículas muy finas (< 0,1 mm) debe ser menor del 1 %, ya que si se aumenta esta proporción puede ocurrir que la eliminación de burbujas presente mayores dificultades.[6]

3.CARACTERIZACIÓN Se han seleccionado nueve muestras con diferente granulometría, para obtener la transparencia adecuada del mosaico vítreo. Con las muestras seleccionadas aptas desde el punto de vista de la granulometría, se han realizado otras técnicas analíticas como son la colorimetría con GretagMacbeth Color-Eye XCH, la Fluorescencia de Rayos X (FRX) realizando una caracterización química semicuantitativa mediante el espectrómetro de fluorescencia de rayos X por dispersión de longitud de onda. S4 Pioneer, Bruker, de forma paralela se realizó la Difracción de Rayos X (DRX) (D5000D) con el fin de observar posibles fases cristalinas y en tercer lugar se realizó una microscopía electrónica, microscopía óptica (JEOL 7001F EDX-WDX Oxford) para observar la distribución de partículas así como su tamaño. De la caracterización química y mineralógica se deduce que el Plano Float es principalmente sílice (71.5%), óxido de sodio (13.5%) y oxido de calcio (9.15%), seguido de otros compuestos como son el óxido de magnesio (3.95%), la alúmina (0.95%), el óxido de potasio (0.35%) y como elementos traza está el hierro (0.075%). De la caracterización mineralógica mediante la difracción de Rayos X se puede deducir que es un material amorfo.

4.RESULTADOS Se parte de una granulometría standard, realizando diferentes ensayos para variar los porcentajes de finos con el fin de modificar la transparencia, sin mermar la resistencia mecánica antes de la cocción de las probetas, pudiendo tener como variable la presión y humedad de prensado.

Figura 1. Granulometría de los ensayos (Figura 1)

Modificando la velocidad de rotación del molino, la carga de bolas, y la carga de material a molturar [7][8], obtenemos 3 grupos con diferentes distribuciones granulométricas, con mayor o menor porcentaje de finos. Este factor será uno de los determinantes en relación a la opacidad de la muestra. Grupo A: Mayor porcentaje de finos (< 75 micras). (A3, A4, A5) Grupo B: Granulometrias standard de trabajo. (B4, B6, B8) Grupo C: Menor porcentaje de finos (<75-100 micras). (C5, C7, C9)

Comunicación Póster

El grado de opalización del vidrio depende de las diferencias entre los índices de refracción de la matriz vítrea y las microheterogeneidades, de su tamaño y número. Estas actúan como centro de dispersión de la luz, desviándola de su dirección primitiva por reflexión y refracción. A igual volumen total de partícula, la opalización es mayor cuanto más elevado es su número y menor su tamaño. Cuando el diámetro de estas es mayor que la longitud de onda de la luz incidente, los rayos al chocar contra dichas partículas sufren una serie de reflexiones parciales y de refracciones sucesivas, dispersándose en múltiples direcciones dando un aspecto lechoso al vidrio [9]. Visualmente se observa que el grupo C, las piezas son más transparentes que el resto de grupos. Esto se confirma con las medidas de la colorimetría de las diferentes pruebas(Tabla1). Situando las probetas sobre un fondo negro estandarizado y midiendo el color, el mejor resultado fue la prueba C9 al tener un índice de blancura inferior, dejando pasar la luz a su través es la más apta para su uso.

L A B Ind. Blancura BLANCO STD EQUIPO 98,55 -0,14 -0,56 98,73 PRUEBA A5 86,44 -2,61 3,57 51,15 PRUEBA B8 81,77 -1,74 1,93 49,85 PRUEBA C9 39,81 -0,07 -0,05 11,61

FONDO NEGRO 25,8 0,06 -0,53 11,02 Medidas colorimétricas (Tabla 1)

Tras la obtención de estos datos, confirmamos los resultados obtenidos por medio del estudio de la microporosidad, donde se observa claramente que varía la transparencia desde una alta densidad de burbujas de tamaño reducido sin apenas distancia entre ellas (muestra A5 (Figura 2)), pasando por un estado intermedio con una densidad media de burbujas (muestra B8 (Figura 3)), hasta una baja densidad de burbujas de un tamaño superior pero con mayor distancia entre ellas ( C9 (Figura 4)), consiguiendo con ello un material de mayor translucidez, sin llegar a ser transparente.

Ensayo A5 (Figura 2)

Ensayo B8 (Figura 3)

Ensayo C9 (Figura 4)

5.CONCLUSIONES Podemos concluir que la variación de la granulometría influye de forma determinante en la obtención de un mosaico vítreo translucido, teniendo como variable limitante la resistencia mecánica antes de cocción. BIBLIOGRAFIA [1] X. ELIAS; “Reciclaje de residuos industriales. Residuos sólidos urbanos y fangos de depuradora” 2ª edición. Madrid (2009). ISBN 978-84-7978-835-3. [2] D. BLANCO; “Diseño de Metodologia para la ubicación de vertederos de residuos de construcción y demolición y para cuantificar los residuos a gestionar. Aplicación a la provincia de Castellón”. Tesis Doctoral. Universitat Jaume I. (2011), 18. [3] J. BERNAD. “Mosaico Vítreo en varios Relieves (Serie Pandora), optimización del proceso productivo en su fabricación y sus ventajas estéticas – comerciales”. Bol.Soc. Esp. Ceram. Vidrio. Vol 49 Nº 2.Marzo-Abril (2010). 13-14. [4]. V. Faubel; J. Romero. “Mezclas vítreas de material reciclado para difusión de luz de led’s. Cromoglass”. Bol.Soc. Esp. Ceram. Vidrio. Vol. 48,Nº 2, (2009) 123-126. [5] J.E. NAVARRO; F. NEGRE “Constitucion de los vidrios”. “Tecnología cerámica”. Volumen V. Universidad de Valencia.(1985) 794-801 [6]. Jesús Mª. Rincón “Materias Primas para la Industria del Vidrio” Instituto E. Torroja de Ciencias de la Construcción, CSIC. Grupo/Lab de Materiales Vítreos y Cerámicos. [7] R.H. SNOW; B.H. KAYE; C.E. CAPES; et.alt “Reducción y aumento de tamaño”, sección 8, en “Manual del Ingeniero Químico”.CHILTON P. 5ª Edición. McGrawHill. México (1973). P.8-3/8-40.ISBN: 0-07-049478-9 [8] V.CABALLER; J. MARCO; F. NEGRE; et. Al. “Mejoría de la blancura de un vidriado mediante la aplicación de un diseño factorial de experimentos”. QUALICER 1994. 6-9 MARZO. CASTELLON. ESPAÑA [9] JOSE MªFERNANDEZ NAVARRO “EL VIDRIO”. CSIC. SECV.3ª edición. Madrid 2003. p.ISBN 84-00-08158-7

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Mechanical properties of reflective porcelainised stoneware ceramic tiles with CuO glazes and Ag-

TiO2 sol-gel coatings. C. Gargori, S. Cerro, M. Llusar, G. Monrós-Andreu*.

Dpto. Química Inorgànica y Orgànica, Universidad Jaume I, Castellón (España). *

2Department of Mechanical Engineering and

Construction, Universidad Jaume I, Castellón (España).

1. Introduction.

Glazes with a metallic appearance can be obtained classically from the crystallization of high refractive phases such as Fe2Fe(P2O7)2 iron (III) iron (II) pyrophosphate or noble metals (Ag, Hg, Cu) in the form of glossy preparations, preparations for burnishing, such as lacquers or pastes, or powdered substances [1]. In this study the mechanical properties of high reflective coatings over porcelainised stoneware ceramic tiles conventionally fired at 1200ºC for solar collection obtained from glazes which crystallize tenorite (CuO) or from silver-titania sol-gel films over fired glazed tiles from polyglicol and acetylacetonate complexes of metallic cations introduced as titanium alkoxides and silver nitrate fired at 400ºC [2]. 2. Experimental and results.

The glaze which crystallizes tenorite was obtained by addition CuO and other modifiers such as TiO2 anatase and MnO2 to conventional frits for porcelainised stoneware (with lead addition or without lead addition using bismuth as ecofriendly substitute). The mixture was milled in water media and the slurry was deposited by a doctor blade procedure. The glazed tile was fired at 1200ºC using a conventional porcelainised stoneware thermal cycle. Silver-titania composites have been deposited by screen printing (90 threads/cm) over a parent glazed and fired porcelainised stoneware tiles from polyglicol (diethylenglycol 40 g) and acetylacetonate (molar ratio acac:Ti=1:1) stabilized inks of titanium alkoxides (isopropoxide ISTi or n-butoxide NBTi) and silver nitrate, fired in oxidising atmosphere at 400ºC/1h [3].

The samples were characterized by the following techniques: (a) the roughness of the surfaces Ra measured up in a conventional SM-3 de Kosaka Laboratory Ltd. Rugosimeter, (b) specular reflectivity Rsp using a X Rite serie SP60 using illuminant D65 and observer 10º, (c) X-ray diffraction of (DRX) with Ni filtered CuK radiation at 0,05 º2/s and constant of time of 2 s., (d ) the Vickers microhardness and the critical tension intensity factor KIc were measured by a microindenter MATSUZAWA using charges of 25-200 g applied during 20 seconds. The tension intensity factor KIc were carried out obtaining located and developed cracks of indentation and applying the Lawn and Fuller law to the development of radial cracks by Roesler, for linear elastic solids [5] to lateral cracks in agreement with the equation 1:

KIc = 0,0513 P c(-3/2) (eq. 1) where KIc is the critical tension intensity factor, P the charge applied in N and c the front length of lateral nucleate crack in the vertexes of the indentation in m (being fulfilled that c/a> 2, being a the diagonal length average measured for the indentation Vickers).

The XRD difractogrammes are shown in Figure 1 and the obtained results in Table 1. X ray diffraction (showing tenorite crystallizations in Cu-glazes, more intense in bismuth glaze, and cristobalite SiO2, anatase and silver metal in silver-titania films) and the Ra (roughness average) around 1 m for all samples. In the case of glazes, the lead based glazes show low fracture thoughnes KIc which gives high brittleness index (HVN/KIc) and therefore low wear resistance of the surface. The ecofriendly glaze using bismuth and niobium addition show the higher Rsp compatible with a decrease of the brittleness index. In the case of Ag-TiO2 sol-gel depositions the reflectivity increase dramatically with the coating but the fracture thoughnes KIc slightly increases and the brittleness index (HVN/KIc) decrease indicating higher wear resistance than the parent glaze.

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Pb glaze 7%Cu5%Mn

Pb glaze 7%Cu5%Mn5%Ti

Bi glaze 7%Cu5%Mn3%Nb

parent glaze

DEG-acac-1,2%IPT-2.25%Ag

DEG-acac-1,2%TBTi-2%Ag

Figure 1 XRD (Intensity versus º2) T(CuO)C(Cristobalite)A(Ag)S(Anatase TiO2)

Sample Ra (m)

HVN (Kg/mm

2)

Rsp (650 nm) (%)

KIc (MPa .m

1/2)

HVN/KIc (µm

-1/2)

Pb glaze 7%Cu5%Mn 0.15(2) 681(5) (25g)* 22 0.41(4) 16.2

Pb glaze 7%Cu5%Mn5%Ti 0.10(2) 560(4) (25g) 26 0.33(2) 16.8

Bi glaze 7%Cu5%Mn3%Nb 0.13(1) 606(6) (25g) 28 0.80(2) 7.4

parent glaze 0.09(2) 618(5) (50g) 3.6 1.05(3) 5.8

DEG-acac-1,2%IPT-2.25%Ag 0.08(2) 584(6) (200g) 35 1.30(4) 4.4

DEG-acac-1,2%NBTi-2%Ag 0.07(2) 606(7) (200g) 38 1.06(3) 5.6

Tab. 1: results obtained in the indicated samples: (standard deviations in parentheses), (* applied charge)

3. Conclusions.

Reflective coatings (specular reflectance 30-40%) over porcelainised stoneware ceramic tiles for solar collection glazes, with and without lead addition, which crystallize tenorite (CuO) using a conventional thermal treatment of porcelainised stoneware (1200ºC) and from sol-gel films, from titanium alkoxides and silver nitrate, deposited by screen preinting and fired at 400ºC over a white parent glaze has been mechanical evaluated. The lead free glaze using bismuth and niobium addition show the higher Rsp compatible with a decrease of the brittleness index. In Ag-TiO2 sol-gel depositions the reflectivity increase dramatically but the fracture thoughnes KIc increases slightly and the brittleness index (HVN/KIc) decrease indicating higher wear resistance than the parent glaze.

References [1] M.J. Cabrera, V. Montíns, A. Foó, P. Balfagón, “Obtainment of glazes with a metallic appearance in single-fired tiles, Qualicer 2006, PBC 253-254 [2] F. Sanmiguel, O.Ruiz, S. Sorli, G. Monrós, Study of the microstructure of high reflectivity films on ceramic glazes, Qualicer 2004, P.GC 111-126. [3] S. Cerro, N. Fas, C. Gargori, M. Llusar, G. Monrós, High reflective ceramic tiles from tenorite glazes and silver-titania sol-gel films over glazes, send for publication, VIII Encuenrro franco-español de Química y Física del Estado Sólido, Vila-Real, Abril 2014. 4] A. R. Boccaccini, The Relationship between Wear Behaviour and Brittleness Index in Engineering Ceramics and Dispersion-Reinforced Ceramic Composites, Interceram 48, 176-187, 1999. 5] W. Semm, S. Fretti, Abrasive Wear of multiphase materials, Castolin SA, Wear, 129, 234-243, 1988.

Acknowledgements: authors gratefully acknowledge the financial support of Fundación Bancaja-UJI (P11B201009 project) and CDTI-Torrecid (10I076 Project).

T T

T T

T

C A

A A A A

A C S S

Comunicación Oral

Membranas inorgánicas de intercambio iónico: efecto de l espesor de los soportes

S. Sales 1, M.M. Lorente 1 J. Gilabert 1, y S. Mestre 1,* 1. Instituto de tecnología Cerámica-AICE. Campus Universitario Riu Sec. Avda. Vicent Sos Baynat s/n. 12004 Castellón (Spain)

*sergio.mestre@itc.uji.es Las membranas de intercambio iónico poseen grandes aplicaciones industriales, siendo su naturaleza mayoritariamente orgánica. Por ello se adaptan mal a procesos en los que intervienen corrientes químicamente agresivas (pH extremo, carácter oxidante, etc.), como las que aparecen en el tratamiento de efluentes líquidos (por ejemplo, los baños de cromado agotados) [1]. Para este tipo de aplicaciones es preciso sintetizar membranas inorgánicas de intercambio iónico, a ser posible con un coste bajo o moderado, lo cual no es posible con las membranas cerámicas comerciales, típicamente basadas en óxidos como la alúmina o la titania. En el presente trabajo se ha investigado la obtención de membranas cerámicas de intercambio iónico de bajo coste, tanto catiónicas como aniónicas. Para ello se ha partido de un soporte poroso bastante económico, desarrollado a partir de mezclas de caolín y alúmina, con almidón como generador de porosidad. La composición final empleada fue 40% caolín, 40% alúmina, y 20% de almidón de patata. Con la mezcla preparada vía húmeda se conformaron por prensado probetas de 5 cm de diámetro y dos espesores diferentes (8 y 4 mm aproximadamente), que fueron sinterizadas con un tratamiento térmico diseñado para conferirles suficiente resistencia mecánica, y a la vez mantener una porosidad elevada. En el interior de los soportes se depositaron dos intercambiadores iónicos diferentes, fosfato de circonio hidratado (HZrP, catiónico) y óxido de circonio hidratado (HZrO, aniónico). El proceso de deposición fue similar en los dos casos. En primer lugar los soportes se impregnaron con una disolución de ZrOCl2 0,5 M por succión, y luego se sumergieron en H3PO4 al 85% para precipitar el HZrP, o NH3 al 30% para precipitar el HZrO, en el interior de la red porosa del soporte. Tras la precipitación, las membranas se lavaron con agua destilada, se secaron y se sometieron a unos tratamientos térmicos optimizados para fijar cada intercambiador sobre el soporte cerámico y reducir en la menor medida posible su capacidad de intercambio iónico (dichos tratamientos se habían definido previamente [2,3]). Este proceso de infiltración se repitió varias veces para obtener membranas con diferentes cantidades de intercambiador depositado. Para todas las membranas obtenidas se determinó la relación entre la masa de intercambiador depositada y la masa del soporte (parámetro λ) como una medida de la evolución del proceso de infiltración. Adicionalmente se evaluaron las distribuciones de tamaños de poro de algunas membranas para determinar la evolución de la microestructura. Los resultados obtenidos indicaron que la deposición de los dos intercambiadores no se producía por el mismo mecanismo, y además el efecto del espesor del soporte era diferente según el intercambiador depositado:

• En el caso del fosfato de circonio, la evolución de λ frente al número de infiltraciones se componía de dos tramos rectos (figura 1), presentando el segundo una pendiente inferior al primero. Ello indicaba que existía un cambio en el mecanismo de deposición a partir de la tercera infiltración. Por otra parte, a igualdad en el número de infiltraciones los soportes con menor espesor también recibían una menor carga de HZrP, lo cual apuntaba a la existencia de otro fenómeno por el cual una parte del Zr4+ infiltrado no precipitaba sobre el soporte, que era más acusado al reducir el espesor del soporte.

• La evolución de λ frente al número de infiltraciones fue mucho más regular en el caso del óxido de circonio hidratado (figura 2). Se obtuvo una relación lineal, y que además era prácticamente independiente del espesor de los soportes.

Comunicación Oral

Figura 1: Evolución de λ frente al número de infiltraciones de fosfato de circonio hidratado y el espesor del soporte.

Figura 2: Evolución de λ frente al número de infiltraciones de óxido de circonio hidratado y el espesor del soporte.

Las diferencias en el proceso de infiltración se reflejaron en la distribución de tamaños de poro de las membranas sintetizadas. En el caso del HZrO la distribución de tamaños se desplazó progresivamente y de modo regular hacia tamaños de poro inferiores, lo cual apuntaba a que la deposición se realizó sobre las superficies internas de los poros. Por el contrario en el caso del HZrP los cambios en la distribución fueron más irregulares, lo cual apuntaba a que la deposición del intercambiador podría realizarse en forma de aglomerados, que incluso podían bloquear parte de los canales de la red porosa. Una posible interpretación de los hechos implicaría que la precipitación del HZrP es relativamente lenta, lo cual permitía que parte del Zr4+ abandonase el soporte bajo el gradiente de concentración generado al sumergir el soporte infiltrado en el H3PO4, fenómeno que ejercería un efecto mayor cuanto más delgado fuese el soporte. Por otra parte, dicha precipitación lenta podría provocar la aparición de grandes aglomerados de HZrP, los cuales al bloquear parte de la red porosa, podrían impedir parcialmente el llenado del soporte con la disolución de ZrOCl2, provocando el cambio en la pendiente apreciado en las gráficas λ = f(infiltración). Siguiendo esta hipótesis, la precipitación del óxido de circonio sería mucho más rápida, y por tanto no permitiría una difusión del Zr4+ hacia la disolución de NH3, de modo que λ sería independiente del espesor, y además no se formarían aglomerados que bloqueasen la red porosa. 7. Agradecimientos Los autores agradecen al Ministerio de Economía y Competitividad el apoyo recibido para el desarrollo de esta investigación (Plan Nacional de I+D, CTQ2012-37450-C02-02). Referencias [1] V.M. Linkov, V.N. Belyakov, “Novel ceramic membranes for electrodiálisis”. Sep. Pur. Technol. 25 (2001)

57-63. [2] M.C. Martí-Calatayud, M. García-Gabaldón, V. Pérez-Herranz, S. Sales, S. Mestre. “ Synthesis and

electrochemical behavior of ceramic cation-exchange membranes based on zirconium phosphate”. Ceram. Int., 39 (2013), 4045-4054.

[3] S. Sales, S. Mestre, M. Lorente M.C. Martí-Calatayud, V. Pérez-Herranz, “Infiltration of hydrous zirconium oxide in low-cost ceramic supports: efect of the number of cycles on the microstructure and the ehectrochemical properties.. 13th Conference of the European Ceramic Society – ECerS XIII Limoges 23-27 June 2013.

[Póster]

La1-xPrxCoO3 (0 ≤ x ≤ 1): microwave-assisted synthesis and physical properties

Julia Mª Gutiérrez Seijas1,*, Jesús Prado-Gonjal1, Rainer Schmidt2, David Ávila1 y Emilio Morán1 1. Dpto. Química Inorgánica I, Facultad CC. Químicas, Universidad Complutense, Madrid

2. Dpto. Física Aplicada, G. F. M. C., Facultad CC. Físicas, Universidad Complutense, Madrid *jmgseijas@ucm.es

1. Introduction The rare-earth cobaltites (RECoO3) are perovskite-type oxides and form an interesting class of materials. These compounds show a variety of important physical properties, such as temperature-induced metal-insulator transitions and different types of magnetic ordering, which are strongly dependent on the spin state of the Co3+. Some of these cobaltites show a spin-state transition of Co3+ cations from a low spin state (LS; t2g

6eg0, S=0) to a intermediate/high spin state (IS: t2g

5eg1, S=1; HS:

t2g4eg

2, S=2) with increasing temperature, followed by the formation of the metallic state of the high spin state at higher temperatures. [1-3] The rare-earth cobaltites are usually synthesized by solid-state reactions involving multiple heating and regrinding steps at high temperatures (≥ 1200 °C) to overcome the solid-state diffusion barriers. We show in this communication that, monophasic rare-earth cobaltites perovskite materials can been obtained by microwave-assisted synthesis in a very fast process within minutes in a single step [4]. Concerning the structure displayed by these compounds, there is a change of symmetry depending on the size of the Rare-Earth cation: LaCoO3 is rhombohedral, S. G., R-3c while for PrCoO3 and for the rest of rare earths, the symmetry becomes orthorhombic, S. G. Pnma. Therefore, the aims of this work are multiple: first, the LaCoO3 and PrCoO3 materials were produced by means of the novel microwave synthesis route. Second, compounds with intermediate compositions La1-x PrxCoO3 (0 < x < 1) were synthesized and their structure and physical properties were investigated. 2. Results Conventional X-ray Rietveld analysis shows that La1-xPrxCoO3 (0 ≤ x ≤ 0.25) displays a rhombohedral perovskite structure while for x > 0.25 the samples are orthorhombic (Figure 1). Rietveld refinements have been performed for both ends of the solid solution with a change in crystal symmetry at x ≈ 0.25.

Figure 1: X-ray diffraction patterns of MW-La1-xPrxCoO3 (0 ≤ x ≤ 1)

Regarding the magnetic properties all samples exhibit paramagnetic behavior, which can be attributed to Co3+ in the intermediate or high spin states, because the low spin state is believed to be diamagnetic. The maximum in the susceptibility vs temperature plots depends on the x content of the rare earth ions present in the phase and reflects a conversion of the remaining high spin Co3+ ions to diamagnetic low spin Co3+.

0 50 100 150 200 250 300

0.005

0.010

0.015

0.020

χ (e

mu/

mol

)

Temperature (K)

LaCoO3

La0.5Pr0.5CoO3

PrCoO3

0 50 100 150 200 250 300-2.0x10-4

-1.0x10-4

0.0

1.0x10-4

dχ/d

T

Temperature (K)

Fig. 3: Magnetic susceptibility (ZFC y FC) at 1 Tesla of MW- La1-xPrxCoO3 (0 ≤ x ≤ 1)

3. Conclusions Single-phase La1-xPrxCoO3 (0 ≤ x ≤ 1) materials have been obtained by microwave-assisted synthesis in a single step. The symmetry of the samples correlates with the rare earth cation content. For x ≥ 0.25 the samples are orthorhombic while for x ≤ 0.25, the material is rhombohedral. Details about high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and the physical properties (magnetic and impedance spectroscopy measurements) will be given and discussed. 4. Acknowledgements Authors. acknowledge financial help from the Community of Madrid (Materyener S2009/PPQ-1626). J.P-G. contribution was possible through a Ph.D. scholarship from the Universidad Complutense de Madrid. R.S acknowledges the MICINN-MINECO for granting a Ramon y Cajal Fellowship. Furthermore, this work was supported by the MICINN through Grants MAT 2010-19837-CO6 and MAT2010-19460. References [1] M.A. Señaris-Rodriguez, J.B. Goodenough, J. Solid State Chem. 116 (1995) 224. [2] M. A. Korotin, S. Y. Ezhov, V. I. SolovyevAnisimov, D.I. Khomskii, G.A. Sawatzky. Phys. Rev. B, 54(8) (1996) 5309. [3] R. Schmidt, J. Wu, C. Leighton, I. Terry, Phys. Rev. B 79 (2009) 125105. [4] J. Prado-Gonjal, E.Morán, Anales de Química 2 (2011) 129.

[Poster]

Microwave-assisted synthesis of superconducting oxides

Irene Herrero-Ansorregui1,*, Jesús Prado-Gonjal1, Emilio Morán Miguélez1 and Miguel Ángel Alario y Franco1

1. Dpto. Química Inorgánica I, Facultad de Ciencias Químicas. Universidad Complutense de Madrid. Avda. Complutense s/n. 28040 Madrid.

*ihansorregui@ucm.es 1. Introduction It is well known that superconducting materials represent a challenge in Solid State Physics and Chemistry as well as in materials Science. Superconducting properties (such as the disappearance of resistivity by applying an electric current, perfect diamagnetism and repulsion of the magnetic field)takes place below the critical temperature (Tc) and magnetic field (Hc) [1]. A lot of research in this field aims to obtain of the highest critical temperature. However, the present communication is centered in the improvement of the synthesis method, in order to obtain known superconducting materials using a fast, cheap, green and easy method. Microwaves are part of the high frequency electromagnetic spectrum (0.3-300GHz). The electric and magnetic components of the electromagnetic wave interact with matter generating magnetic and dielectric losses that cause heating. The phenomenon responsible for them is the polarization or redistribution of charges. So, any material with a dipole moment can be heated with microwave radiation. Microwave-assisted synthesis of ceramic materials, presents many advantages (penetrating radiation, fast and selective heating) compared with the “classical” methods [2]. The objective of this work is then obtaining of superconducting materials using microwave radiation [3]. 2. La2CuO4+δ Lanthanum copper oxide was obtained with the solid-state reaction of the precursors in a domestic microwave oven. The material was oxidized by the chemical-via with bleach (NaClO aq.) at room temperature. By this means the superconducting material can be synthesized in 5 hours and a half. In Images 1 and 2 we show the X-ray diffraction pattern and a microstructure photograph as well as a preliminary magnetic characterization.

0 10 20 30 40-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

50

χ (e

mu/

mol

)

T (K)

Fig. 1 and 2: Rietveld refinement, TEM image, SAED and magnetic susceptibility of La2CuO4+δ

3. YBa2Cu3O7-δ YBCO was obtained at the same procedure. It requirs a short thermal treatment in a conventional oven at 950ºC. In the XRD diagram we did also find Y2BaCuO5, the ”green phase” as a secondary one (Image 3). As we show in Image 4 the magnetic behavior agrees with that expeted for Ybco.

[Poster]

0 20 40 60 80 100 1

-50

-40

-30

-20

-10

0

20

χ (e

mu/

mol

)

T (K) Fig. 3 and 4: Rietveld refinement, TEM image, SAED and magnetic susceptibility of YBa2Cu3O7-δ

4. Ba0.15La1.85CuO4 This material was synthesized using a sol-gel microwave assisted synthesis. The precursor gel was prepared with PVA as polymerizing agent at 80ºC. Then the gel was treated in the microwave domestic oven. Then the porous solid appeared was introduce in a conventional oven for 10 hours. In Images 5 and 6 we show the structural and magnetic characterization.

0 10 20 30 40 50 60 70 80 90 100-2.0

-1.5

-1.0

-0.5

0.0

χ (e

mu/

mol

)

T(K)

Fig. 5 and 6: Rietveld refinement, SEM images, SAED and magnetic susceptibility of Ba0.15La1.85CuO4 5. Conclusions Three copper based superconducting materials have been synthesized using the microwave radiation. All of them are superconducting at the expected critical temperature. In the case of Ba0.15La1.85CuO4 the presence of the barium makes necessary the microwave-assisted sol-gel method, due to the somewhat more complicated stoichiometry. In all cases the microwave assisted synthesis represents an improvement of the classical methods effectively being an easy, fast and green method. 6. Acknowledgements Authors. acknowledge financial help from the Community of Madrid (Materyener S2009/PPQ-1626) and J.P-G. Ph.D. a scholarship from Universidad Complutense. References [1] M. A. Alario, J. L. Vicent, “Superconductividad”. 1ª edición. Madrid, EUDEMA Universidad, 1991 [2] J. Prado-Gonjal, E.Morán, Anales de Química 2 (2011) 129 [3] D. R. Baghurst, A. M. Chippindale, D. M. P. Mingos, Nature, 24, (1988), 322

Nanomaterials for cultural heritage: synthesis and characterization of colloidal systems for

application in conservation of wall paintings and carbonate materials

Livio Ferrazza1,2, Eloísa Cordoncillo Cordocillo1, Héctor Beltrán Mir1,*

1Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón, Campus del Riu Sec, E-12071,

Castellón de la Plana, Spain 2Laboratorio Materiales, Instituto Valenciano de Conservación y Restauración de Bienes Culturales Culturarts

Generalitat, C/ Pintor Genaro Lahuerta 25 46010, Valencia, Spain * mir@uji.es

This work shows a first study about the preparation and characterization of nanostructured BaO suspensions and their evaluation to the consolidation and protection of wall paintings, plasters and stones. The study of BaO nanoparticles synthesis is developed to introduce a series of modified to improve the effectiveness of conservation treatments. These particles appear as an interesting material to be used in conservation and preservation treatments of carbonate materials and wall paintings. BaO was synthesized by coprecipitation method in non-aqueous solutions. The nanoparticles were characterized by transmission electron microscopy (TEM) showing that all synthesis carried out with different experimental conditions gave a 20-50 nm particle size. The application of these BaO nanoparticles on samples of wall paintings was also evaluated. Optical microscopy (OM), scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD) and UV-Vis spectroscopy were the used techniques to characterize the materials, and also to evaluate the effectiveness of treatments to the consolidation and protection. Results indicated that the nanostructurated BaO products may have a protection or pre-consolidation function on wall paint layers. The superficial application of the product forms a thin layer, compatible with the chemical nature of the wall painting and produces a consolidating action on the surface.

New ordered states in the Ca2Mn3O8-δ system A. Mazarío-Fernández1, A. Torres-Pardo1,2, R. Cortés-Gil1,2, A. Varela1, M. Parras1, M. Hernando1,

J.M. González-Calbet1 1. Dpto. Química Inorgánica I, Facultad CC. Químicas, UCM, 28040, Madrid

2. CEI Campus Moncloa, UCM-UPM, Madrid, Spain Manganese related perovskites (AMnO3, A=alkaline earth) present a wide range of fascinating functional properties due to the ability of Mn to adopt several oxidation states and different coordination polyhedra. Regarding their catalytic behaviour, CaMnO3-δ selectively oxidizes, at least on a laboratory scale, propene to benzene and 2-methyl propene [1]. Moreover, the Ca-Mn-O system presents a great variety of oxides with different Ca/Mn ratio and crystalline structure and a particular behaviour: their reduction process leads to a rock-salt type structure which, in most cases, can be oxidized to the starting material [2]. Actually, the system CaMnO3-δ constitutes a good example of stabilization of several metastable perovskite-related phases with Mn in different oxidation states (from Mn4+ to Mn2+). When heated under reducing atmosphere, CaMnO3 is topotactically reduced to CaMnO2.5 through intermediate oxygen-deficient perovskite phases with ordered oxygen vacancies. In this compositional range, the cationic structural framework of the oxidized precursor CaMnO3 is preserved. The final product of the CaMnO3 reduction process is CaMnO2, a rock-salt-related phase. The CaMnO3-CaMnO2 topotactic reduction-oxidation process takes place via oxygen diffusion while the cationic sublattice remains almost unaltered. Extra superlattice reflections in selected area electron diffraction patterns indicate doubling of the CaMnO2 rock-salt cell along the cubic directions of a distorted rhombohedral cell originated by ordering of Ca2+ and Mn2+ ions distributed in nanoclusters into a NaCl-type matrix, as evidenced by dark field electron microscope images.

The local nature of the information provided by the transmission electron microscopy techniques used to characterize the rock-salt type Ca1-xMnxO solid solution clearly hints at the existence of subtle extra ordering in other upper oxides of the Ca-Mn-O system. We use in this paper the combination of oxygen engineering techniques performed under adequate controlled atmosphere with local characterization techniques like electron microscopy with spectroscopic ones like energy electron loss spectroscopy (EELS) to provide a very complete characterization of another member of this system. In particular, Ca2Mn3O8 crystallizes in a layered structure with all Mn4+ in octahedral coordination. The reduction process of this material leads to Ca2Mn3O5 with all Mn2+ octahedrally coordinated in a rock-salt type structure (Fig. 1). By means of partial reductions, several oxides with Mn in intermediate oxidation states and therefore materials with different functional properties have been stabilized. Once again, the reduction and oxidation process of this system is reversible. The different samples obtained in the Ca2Mn3O8-δ system have been characterized by using imaging High Angle Annular Dark Field (HAADF) and Annular Bright Field (ABF) techniques associated to EELS and Energy Dispersive Spectroscopic (EDS) techniques in an aberration-corrected electron microscope with atomic resolution. The structural evolution and the local variation of the Mn oxidation state in different phases with different anionic composition will be discussed (Fig. 2).

Fig.1.- Reduction-oxidation process corresponding to the Ca2Mn3O8-δ system.

Fig. 2.- HREM image along [010] corresponding to Ca2Mn3IVO8.

References [1] A. Reller, J. M. Thomas, D. A. Jefferson and M. K. Uppal, Proc. R. Soc. Lond. A, 394 (1984), 223-241. [2] A. Varela, S. de Dios, M. Parras, M. Hernando, M.T. Fernández-Díaz, A.R. Landa-Cánovas and J.M. González-Calbet, J. Am. Chem. Soc., 131 (2009), 8660-8668.

Obtención de nanopartículas de vanadato de itrio dopado con erbio y con cromo

Lorena Alcaraz 1 y Josefa Isasi 1,* 1. Dpto. de Química Inorgánica I, Universidad Complutense de Madrid, Avda Complutense s/n 28040, Madrid

* e-mail: isasi@quim.ucm.es La mejora de las propiedades luminiscentes de fases de vanadato de itrio dopado con diferentes tierras raras, para su utilización en ciertos dispositivos ópticos, ha impulsado su estudio a lo largo de los años. Diferentes métodos de preparación se han empleado para la obtención de estas fases, en el intento de actuar sobre la morfología de las partículas y conseguir una mejora de su emisión luminiscente [1]. Entre los métodos de síntesis utilizados se incluyen la coprecipitación, el empleo de rutas coloidales, los procesos sol-gel o la síntesis hidrotermal. En general, a diferencia de los métodos convencionales que requieren altas temperaturas y que conllevan un incremento del tamaño de partícula, los procesos sol-gel, los métodos de química coloidal o la síntesis hidrotermal permiten la obtención de fases con tamaño de partícula controlado, lo que puede llegar a incrementar la probabilidad de que se produzcan emisiones espontáneas y, por tanto, la mejora de las propiedades ópticas de las fases obtenidas [2]. La luminiscencia también puede verse modificada con el dopaje efectuado. En este sentido, investigaciones previas han mostrado una diferente emisión luminiscente cuando en el vanadato de itrio dopado se sustituye la tierra rara o el vanadio por cromo [3]. Se exponen en este trabajo los resultados obtenidos en la preparación y en la caracterización estructural y morfológica de ortovanadatos Y0.9Er0.1V1-xCrxO4 (con x = 0 y 1) cuando se emplean diferentes condiciones de reacción. Agradecimientos Los autores agradecen a la Fundación Neurociencias y Envejecimiento (189/2012; 14/2013 y 177/2013) la financiación concedida para el desarrollo de este trabajo. Referencias [1] S. Ray, A. Banerjee, P. Pramanik, “Shape controlled synthesis, characterization and photoluminescence

properties of YVO4:Dy3+/Eu3+ phosphors”. Mat. Sci. Eng. B, 156, (2009), 10-17. [2] R.M. Mohamed, F.A. Harraz, I.A. Mkhalid, “Hydrothermal synthesis of size-controllable Yttrium

Orthovanadate (YVO4) nanoparticles and its application in photocatalytic degradation of direct blue dye”. J. Alloy. Comp., 532, (2012), 55-60.

[3] L. Alcaraz, J. Isasi, M. Fernández, C. Díaz-Guerra, “Effect of synthesis conditions on the structural characteristics and luminescence properties of Y0.9Eu0.1V1-xCrxO4 (0 ≤ x ≤ 0.5) nanopowders”. Mater. Chem. Phys., (2014), In press.

Póster

Obtención de pigmentos cerámicos rojos con estructura perovsquita. Efecto del mineralizador

E. Miguel1, J.B. Carda2, M.D. Notari1, *J. LLop1, I. Nebot Díaz1

1. Escola Superior de Ceràmica de l’Alcora 2. Dpto. Química Inorgánica y Orgánica, Universitat Jaume I, Castellón

*jordi.llop@escal.es 1. Resumen

En el presente trabajo, se estudia cual es el efecto de la utilización de diferentes mineralizadores en la obtención de un pigmento rojizo basado en la estructura perovskita, con composición (Y,AlCr)O3. Se han estudiado diferentes estequiometrías, así como diferentes proporciones y tipos de mineralizadores, variando la temperatura desde 1200ºC a 1500ºC, para conseguir mayoritariamente la estructura perovskita, responsable última del desarrollo del color con tonalidad roja. Los mejores resultados se han obtenido con mineralizadores basados en fluoruros, y se ha conseguido demostrar mediante la técnica de absorción UV-Vis, la presencia de Cr(IV) en la estructura resultante. El tamaño de partícula en todos los casos, es inferior a 5µm, lo que lo hace viable para posibles aplicaciones donde el tamaño de partícula es importante para el desarrollo de las mismas.

On the first-order structural transition in the multiferroic perovskite-like formate

[(CH3)2NH2][Mn(HCOO)3] Manuel Sánchez-Andújar1, Lilian Claudia Gómez-Aguirre1, Breogan Pato-Doldán1,

Juan Manuel Bermúdez-García1, Susana Yáñez-Vilar2, Ramón Artiaga2, Rudra Sekhar Manna3, Frank Schnelle3, Michael Lang3, Frank Ritter3, Amir Abbas Haghighirad3,4 ,

María Antonia Señarís-Rodríguez1*

1. Dpt. Fundamental Chemistry, University of A Coruña, Campus A Coruña, 15071 A Coruña, Spain.

2. Dpt. Industrial Engineering II, University of A Coruña, Campus Ferrol, 15403 Ferrol, Spain. 3. Institute of Physics, Goethe University, 60438 Frankfurt am Main, Germany.

4. Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, U.K. *m.senaris.rodriguez@udc.es

Introduction Multiferroic materials, in which magnetic and electrical ordering coexist,1 have received much attention in the last few years in view of their potential applications to magnetic storage, novel circuits, sensors, microwave and high-power applications.2,3 However, up to date single phase multiferroics are rare as the conventional mechanism for ferroelectric and cooperative magnetism are mutually exclusive.4 Beyond transition-metal oxides, that have been extensively investigated,5 the family of hybrid inorganic-organic materials are attracting increased attention.6-9 Among them, the dense metal–organic frameworks (MOF) of formula [(CH3)2NH2][M(HCOO)3] (with M2+ = Mn2+, Co2+, Ni2+ and Fe2+)7,10 with perovskite ABX3 architecture (where A = [(CH3)2NH2]+, B = M2+, X = HCOO-) are specially interesting as type I-multiferroics: they combine structural flexibility, relatively good stability, low density and cooperative magnetic and electrical properties. Out of all [(CH3)2NH2][M(HCOO)3] compounds the Mn-formate -which shows a magnetic transition at TN ≈ 8.5 K,7 a dielectric transition at Tt ≈ 190 K7,10 and according to a recent report a new magnetoelectric coupling in the paramagnetic state near the ferroelectric transition11- is so far the best characterized one, even if a number of questions remain open, for example, if the structural transition is a first or second order transition. According to the literature, at room temperature this compound shows trigonal symmetry (space group: R-3c, Z = 6), figure 1a. In this phase, the [(CH3)2NH2]+ (DMA) cations are disordered with the nitrogen atom equally distributed in three different positions, and the Mn2+ ions residing in a regular [MnO6] octahedral environment. Meanwhile at 100 K (the only temperature below the dielectric transition for which crystal data are available)10 this compound shows monoclinic symmetry (space group: Cc, Z = 4), where the DMA cations are cooperatively ordered and the [Mn(HCOO)3]- framework is strongly distorted,10 see figure 1b.

Figure 1.-Conventional perovskite structure view and unit cell of [(CH3)2NH2][Mn(HCOO)3] (a): at room temperature (HT trigonal phase) (b): at 100 K (LT monoclinic phase).

(a) (b)

The goal of this work is to shed more light on the phase transition experienced by the Mn-formate [(CH3)2NH2][Mn(HCOO)3] that, as indicated above, is associated with the dielectric transition and the onset of magnetoelectric coupling in the paramagnetic state.11 For this purpose, we explore the overall structural behavior of the [(CH3)2NH2][Mn(HCOO)3] compound across the temperature range where the dielectric transition takes place by means of high-resolution thermal expansion measurements on high-quality single crystals, calorimetric experiments on crushed single crystals and temperature dependent X-ray diffraction studies on both powders and single crystals. The results obtained from different techniques across the transition clearly proof the presence of an abrupt structural phase transition at Tt~187 K, the temperature at which the sharp dielectric transition takes place. This structural transition that involves a symmetry change from R-3c to Cc, a discontinuous variation of the unit cell parameters and unit cell volume, and a very sharp and rather large step-like thermal expansion anomaly is clearly of first order. In addition, the calorimetric results clearly point out to a 3-fold order-disorder transition, as also supported by the crystal structure studies. Concomitant to the transformation from R-3c to Cc twinning of the crystals occurs, and the low temperature (LT) phase contains 3 twin domains related to each other by a rotation of 120º around the c* axis, each of them corresponding in fact to one of the three possible orientations of the N atom of the dimethylammonium (DMA) cations in the high temperature (HT) phase. Also, the results obtained from resolving the crystal structure at temperatures just above and below the phase transition, reveal the relevance of the distortion of the rather flexible [Mn(HCOO)3]- framework, in particular the isotropic/anisotropic tilting of the [MnO6] octahedra, in the overall structural transition that also involves the cooperative ordering of the DMA-cations. In addition, the calculated pressure dependence of the transition temperature is rather large (dTt/dP= 4.6 0.1 K/kbar), so that it should be feasible to shift it to room temperature using adequate external or internal pressure rendering this and related materials much more interesting for technological applications. Acknowledgements The authors are grateful for financial support from Ministerio de Economía y Competitividad (MINECO) (Spain) and EU under projects FEDER MAT2010-21342-C02-01, from Xunta de Galicia under project PGIDIT10PXB103272PR and from the German Science Foundation DFG in frame of SFB/TR49. L.C.G.A. also wants to thank UDC for a Predoctoral fellowship. References [1] M.J. Fiebig, “Revival of the magnetoelectric effect”. Journal of Physics D: Applied Physics, 38, (2005),

R123-152. [2] J.F. Scott, “Data storage: Multiferroic memories”. Nature Materials, 6, (2007), 256-275. [3] Y.-H. Chu, L.W. Martin, M.B. Holcomb, M. Gajek, S.-J. Han, Q. He, N. Balke, C.-H. Yang, D. Lee, W. Hu,

Q. Zhan, P.-L. Yang, A. Fraile-Rodriguez, A. Scholl, S.X. Wang, R. Ramesh, “Electric-field control of local ferromagnetism using a magnetoelectric multiferroic”. Nature Materials, 7, (2008), 478–482.

[4] N.J. Hill, “Why Are There so Few Magnetic Ferroelectrics?” The Journal of Physical Chemistry B, 104, (2000), 6694-6709.

[5] S.-W. Cheong, M. Mostovoy, “Multiferroics: A magnetic twist for ferroelectricity”. Nature Materials, 6, (2007), 13-20.

[6] A.K. Cheetham, C.N.R. Rao, “There's Room in the Middle”. Science, 318, (2007), 58-59. [7] P. Jain, V. Ramachandran, R.J. Clark, H.D. Zhou, B.H. Toby, N.S. Dalal, H.W. Kroto, A.K. Cheetham,

“Multiferroic Behavior Associated with an Order−Disorder Hydrogen Bonding Transition in Metal−Organic Frameworks (MOFs) with the Perovskite ABX3 Architecture”. Journal of the American Chemical Society, 131, (2009), 13625-13627.

[8] H. Cui, Z. Wang, K. Takahashi, Y. Okano, H. Kobayashi, A. Kobayashi, “Ferroelectric Porous Molecular Crystal, [Mn3(HCOO)6](C2H5OH), Exhibiting Ferrimagnetic Transition”. Journal of the American Chemical Society, 128, (2006), 15074–15075.

[9] A. Stroppa, P. Jain, P. Barone, M. Marsman, J. M. Perez-Mato, A. K. Cheetham, H. W. Kroto, S. Picozzi, “Electric Control of Magnetization and Interplay between Orbital Ordering and Ferroelectricity in a Multiferroic Metal–Organic Framework”. Angewandte Chemie International Edition, 50, (2011), 5847-5850.

[10] M. Sánchez-Andújar, S. Presedo, S. Yáñez-Vilar, S. Castro-García, J. Shamir, M. A. Señarís-Rodríguez, “Characterization of the Order−Disorder Dielectric Transition in the Hybrid Organic−Inorganic Perovskite-Like Formate Mn(HCOO)3[(CH3)2NH2]”. Inorganic Chemistry, 49, (2010), 1510-1516.

[11] W. Wang, L.-Q. Yan, J. -Z. Cong, Y.-L. Zhao, F. Wang, S.-P. Shen, T. Zou, D. Zhang, S.-G. Wang, X.-F. Han, Y. Sun, “Magnetoelectric coupling in the paramagnetic state of a metal-organic framework.” Scientific Reports, 3, (2013), 2024.

Order-disorder phenomena in both cationic and anionic sublattices in manganese related

perovskites

Daniel González-Merchante1, Raquel Cortés-Gil1,2, M. Luisa Ruiz-González1, Almudena-Torres-Pardo1,2, José M. Alonso3, Enrique Iborra4 and José M. González-Calbet1,*

1. Departamento de Química Inorgánica, Facultad de Químicas, Universidad Complutense (UCM), 28040-Madrid, Spain. 2. CEI Campus Moncloa, UCM-Universidad Politécnica (UPM) de Madrid, 28040-Madrid, Spain

3. Instituto de Ciencia de Materiales, CSIC, C/ Sor Juana Inés de la Cruz, 3, 28049-Madrid, Spain 4. Departamento de Tecnología Electrónica, E.T.S.I.T, UPM, 28040-Madrid, Spain

*jgcalbet@ucm.es Manganese mixed oxides, exhibiting perovskite related structure, have been extensively studied as a consequence of their catalytic and transport properties linked to the coexistence of several manganese oxidation states: Mn2+, Mn3+ and Mn4+. In this landscape, the La1-xAExMnO3 (AE=Ca, Sr) system occupies a prominent place due to the appearance of colossal magnetorresistance behaviour [1] and other interesting compositional dependent physical phenomena. Actually, since the doping level is modified the occupancy of the 3d band changes as a consequence of the coexistence of different Mn3+/Mn4+ ratio, and different electrical and magnetic behaviours are rendered [2]. Even more, other chemical strategies such as the incorporation of vacancies either at the cationic, (La1-xAEx)zMnO3, or anionic, La1-xAExMnO3-δ,sublattices can be applied, enhancing the possibilities. Actually, compositional variations are on the basis of the development of new materials and a precise characterization is required for understanding the properties of the as prepared solids. Nowadays, the integration of spherical aberration correctors in transmission electron microscopes has given direct access to oxide structural defects with atomic resolution [3]. This enhancement in instrumental performance, in terms of spatial and energy resolution, allow exploring the local properties of functional oxides at the most refined scale, giving valuable microscopic insight into the local structure that ultimately determines their functional properties. Exploiting these advantages has been mainly related to the characterization of well-ordered artificial heterostructures but is an emerging and attractive tool for solving intricate structural and analytical problems in complex oxides and related solid state systems in powdered form. In this context, the aim of this work is to show several examples of how strong correlated manganese oxide systems exhibiting different heterogeneities at the cationic and anionic sublattices can be precisely characterized through the ensemble of atomically-resolved Electron Energy Loss Spectroscopy (EELS), High Angle Annular Dark Field (HAADF) imaging and Annular Bright Field (ABF) imaging techniques. Local defects in two different systems, La0.5AE0.5MnO3 and (La1-xSrx)zMnO3-δ, will be discussed. The motivation of the first system, La0.5 AE0.5MnO3, is related to elucidate if whether or not there is any compositional difference at atomic level in the La/AE distribution over the A site of the perovskite that could provide different local interactions, affecting to the bulk behaviour. The polycrystalline samples were prepared following standard procedures previously reported. The HAADF study reflects the presence of a heterogeneous distribution of the La and AT cations. For instance, figure 1a is a representative HAADF image of the La0.5Ca0.5MnO3 sample along [100] zone axis in which contrast differences at the A site of the perosvskite lattice are evident. Since under the HAADF configuration, the contrast at the image is highly dependent on the atomic number, the brightest constrast could correspond to La richer columns of atoms while the less brilliant to richer Ca columns of atoms. This information is complemented with a compositional analysis by means of EELS at atomic resolution as depicted in the corresponding maps for each element shown in figure 1b. In the case of the La0.56Sr0.44MnO2.5 compound [4], conventional TEM indicated the presence of disorder along b direction. The aberration corrected electron microscopy has clarified this situation. Actually, the sample exhibits two types of rock-salt (RS) blocks, as evidenced in HAADF image depicted in figure 2a. The different contrast of the indicated blocks (see figure 2a) suggests compositional differences. The chemical maps obtained from the Mn-L2,3, La-M4,5, and Sr-M4,5 signals (figure 2) unambiguously indicate that Mn cations are located at the B position of the perovskite structure but also in the less brightest rock-salt defect layer (DRS-1) while La/Sr cations occupy the A perovskite positions as well as those corresponding to the brightest rock-salt defect layer (DRS-2). Conductivity measurements performed in these materials will be discussed.

. Figure 1. (a) HAADF image corresponding to La0.5Ca0.5MnO3; (b) EELS spectra sum, acquired over the area marked in (a), showing the Mn-L2,3, La-M4,5 and Ca-L2,3 signals; (c) HAADF image simultaneously recorded to EELS acquisition; (d) mapping obtained for the Ca-L2,3 signal (e) mapping obtained for the La-M4,5 signal; (f) mapping obtained for the Mn-L2,3 signal.

Figure 2. (a) HAADF image corresponding to La0.56Sr0.44MnO2.5; (b) Area of the HAADF image selected for EELS study; (c) EELS spectra sum showing the Mn-L2,3, La-M4,5 and Sr-M4,5 signals; (d) HAADF image simultaneously recorded to EELS acquisition; (e) mapping obtained for the La-M4,5 signal; (f) mapping obtained for the La-M4,5 signal; (f) mapping obtained for the Sr-M4,5 signal. References [1] S. Jin, T. H. Tiefel, M. McCormac, R. A. Fastnacht, R. Ramesh and L. H. Chen, Science 264, (1994), 413-

415 . [2] P. Schiffer, A. Ramírez, W. Bao and S.-W. Cheong, Phys. Rev. Lett., 75, (1995), 3336-3339. [3] D. A. Muller, L. Fitting Kourkoutis, M. Murfitt, J. H. Song, H. Y. Hwang, J. Silcox, N. Dellby, and O. L.

Krivaneket. Science 319, (2008), 1073-1076. [4] M. Luisa Ruiz-González, Raquel Cortés-Gil, Almudena Torres-Pardo, Daniel González-Merchante, José M.

Alonso, and José M. González-Calbet, Chemistry A European Journal19, (2013), 1-6.

0.39 nm

P

[100]

0.39 nm

DNaCl- 1

DNaCl- 2

0.39 nm

P

[100]

0.39 nm

DRS-1

DRS-2

(a)

(c) (c)[100]

(a) (b) (b)

(d)

(e)

(f)

(d)

(f)

(g)

(e)

Comunicación Oral

Preparación de nanopartículas de magnetita mediante polioles

Noemí Montoya, Pablo Pardo, José Miguel Calatayud, Hadiseh Tabaie y Javier Alarcón

Universidad de Valencia, Departamento de Química Inorgánica, Calle Doctor Moliner 50, 46100-Burjasot (Valencia) España javier.alarcon@uv.es

1. Introducción Las nanopartículas de magnetita o Fe3O4 poseen un gran interés debido a sus propiedades magnéticas y eléctricas. Las extensas aplicaciones de la magnetita incluyen: gran densidad de almacenamiento de información, dispositivos electrónicos, tecnología de ferrofluidos, catálisis, pigmentos, etc. En los últimos años, la magnetita ha captado mayor atención por sus aplicaciones biomédicas como administradores de fármacos, hipertermia del cáncer y en imágenes de resonancia magnética (MRI) debido a su no toxicidad y alta estabilidad química. A este respecto, es necesario obtener nanopartículas de magnetita dispersables en medio acuoso, superparamagnéticas y fácilmente reproducibles a gran escala [1-3]. La síntesis de las nanopartículas de magnetita se llevó a cabo mediante técnica de polioles, por reflujo a 280 °C y proceso solvotermal a 200 °C [4,5]. La síntesis mediante reflujo de polioles ofrece la posibilidad de controlar cinéticamente las condiciones experimentales y es fácilmente escalable [1]. El proceso solvotermal es uno de los más utilizados para la obtención de nanomateriales de óxido de hierro ya que permite alcanzar una buena cristalinidad [3-5]. Todos los experimentos se llevaron a cabo mediante el uso de trietilenglicol (TREG). El TREG ofrece partículas de magnetita no aglomeradas, con forma uniforme y una distribución de tamaños estrecha [1]. Los resultados han permitido alcanzar las condiciones óptimas de trabajo para obtener la forma, el tamaño y la cristalinidad de las partículas de magnetita deseadas. Es de destacar la alta solubilidad en agua lo que permite su potencial aplicación en biomedicina. Agradecimientos Se agradece la financiación del Ministerio de Ciencia y Tecnologia por la financiación al proyecto

Consolider Ingenio (CSD2010-00065) y al proyecto Prometeo (2011/008) de la Generalitat Valenciana.

Referencias [1] W. Cai, J. Wan, “Facile synthesis of superparamagnetic magnetite nanoparticles in liquid polyols”, J. Coll.

Interf. Scien. 305, (2007), 366-370. [2] S. Jiao, M. Xu, Y. Zhang, G. Pang, S. Feng, “Influence of polyols on the formation of iron oxide nanoparticles

in solvothermal system”, J. Nanosc. Nanotech., 10, (2010), 8405-8407. [3] J. Wang, M. Yao, G. Xu, P. Cui, J. Zhao, “Synthesis of monodisperse nanocrystals of high crystallinity

magnetite through solvothermal process”, Mat. Chem. Phys., 113, (2009), 6-9. [4] N. Florini, G. Barrera, P. Tiberto, P. Allia, F. Bondioli, “Nonaqueous Sol-Gel synthesis of magnetic iron oxides

nanocrystals”, J. Am. Ceram. Soc., 96, (2013), 3169-3175. [5] N. Pinna, G. Garnweitner, M. Antonietti, M. Niederberger, “A general nonaqueous route to binary metal oxide

nanocrystals involving a C-C bond cleavage”, J. Am. Ceram. Soc., 127, (2005), 5608-5612.

Póster para el VII Encuentro Franco-Español Química-Física del estado sólido.

 

TÍTULO: Reciclado del vidrio en el desarrollo de nuevos soportes cerámicos.

AUTORES: A. Muñoz Galindo, J.J Vázquez Esteller, T. Vivó Muñoz.

AFILIACIÓN: Estudiantes de Grado de Ingeniería Química en la Universidad Jaume I de Castellón.

TEMA: Materiales cerámicos.

ABSTRACT: Study based on theoretical literature on the introduction of recycled glass in ceramic substrates, ceramic raw materials and other recycled materials such as ceramics industry sludge. The objective is to minimize the consumption of natural resources, reduce waste, increase efficiency and effectiveness in the process of production of ceramic tiles.

RESUMEN:    Estudio teórico basado en bibliografía sobre la introducción de vidrio reciclado dentro de soportes cerámicos, con materias primas cerámicas y otros materiales reciclados como los fangos de la industria cerámica. El objetivo es minimizar el consumo de recursos naturales, reducir residuos, aumentar la eficacia y la eficiencia en el proceso de producción de azulejos cerámicos.

Póster para el VII Encuentro Franco-Español Química-Física del estado sólido.

 

TÍTULO: Reciclado del vidrio en el desarrollo de nuevos soportes cerámicos.

AUTORES: A. Muñoz Galindo, J.J Vázquez Esteller, T. Vivó Muñoz.

AFILIACIÓN: Estudiantes de Grado de Ingeniería Química en la Universidad Jaume I de Castellón.

TEMA: Materiales cerámicos.

ABSTRACT: Study based on theoretical literature on the introduction of recycled glass in ceramic substrates, ceramic raw materials and other recycled materials such as ceramics industry sludge. The objective is to minimize the consumption of natural resources, reduce waste, increase efficiency and effectiveness in the process of production of ceramic tiles.

RESUMEN:    Estudio teórico basado en bibliografía sobre la introducción de vidrio reciclado dentro de soportes cerámicos, con materias primas cerámicas y otros materiales reciclados como los fangos de la industria cerámica. El objetivo es minimizar el consumo de recursos naturales, reducir residuos, aumentar la eficacia y la eficiencia en el proceso de producción de azulejos cerámicos.

[Póster]

Reducing the nonlinear effect by controlling the sintering atmosphere

Xavier Vendrell1*, José E. García2, Fernando Rubio-Marcos3, Diego A. Ochoa2, Jose F. Fernandez3 y Lourdes Mestres1

1. Grup de Química de l’Estat Sòlid, Dept. Química Inorgànica, Universitat de Barcelona, 08028, Barcelona, Spain 2. Department of Applied Physics, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain

3. Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049 Madrid, Spain *xavier.vendrell@ub.edu

Excellent piezoelectric and electromechanical properties were achieved in a series of lead-based ferroelectric ceramics, especially Pb(Zr,Ti)O3 (PZT). As the electromechanical properties of PZT are attributed to the morphotropic phase boundary (MPB) [1], strong emphasis was laid on investigating systems containing MPBs. Environmental issues, however, may ultimately require the replacement of these lead-based materials of the electronic components [2]. Therefore, extensive studies on MPB lead-free materials have been undertaken [3].

Over the last few years, a lot of attention has focused on (K,Na)NbO3 (KNN) based ceramics because of their good electromechanical properties and high Curie temperature for compositions close to MPB [4]. Unfortunately, it is difficult to obtain samples with such characteristics by a technological and economically available process although good piezoelectric properties have been reported for samples obtained by conventional ceramic route.

Particularly, the composition (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNL-NTS) exhibits interesting

properties, that make it probably the most workable lead-free piezoelectric system known to date [5]. Nevertheless, some of their properties are not suitable for all purpose. KNL-NTS ceramics show a noticeable nonlinear behaviour (i.e. properties dependent of the applied electric field and/or mechanical stress) which is due mainly to extrinsic effects [6]. As a consequence, research fields are open in order to obtain new KNN-based materials capable to replace hard PZT in power devices.

Thus, it is interesting to explore different ways to improve the nonlinear behaviour in KNN systems. It is well known that sintering atmosphere could determine the appearance of oxygen vacancies in perovskite systems. As a consequence, sintering atmosphere could influence KNL-NTS properties by reducing, for example, nonlinear response [7,8]. Consequently, the effect of sintering conditions on the structural and nonlinear dielectric properties of KNL-NTS ceramics was studied in this work.

Dense lead-free (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 piezoelectric ceramics are prepared by the conventional solid state reaction. The effect of different sintering conditions (synthetic air, O2 and Ar) on some structural, dielectric and piezoelectric properties are studied. Long sintering time (16h) promotes the formation of a secondary phase. High values of longitudinal piezoelectric constant are obtained when ceramics are sintered under Ar or O2 for low dwell time (2h). However, nonlinear response turns out to be significantly dependent of the sintering atmosphere. Results are discussed taking into account the formation of complex defects, capable to pin domain wall, when sintering promotes the creation of oxygen vacancies. Sintering in an inert atmosphere seems to be a good via to reduce nonlinear response in KNN-based piezoceramics.

[Póster]

References

[1] B. Noheda, "Structure and high-piezoelectricity in lead oxide solid solutions". Curr. Opin. Solid State Mater. Sci. 6 (2002) 27–34.

[2] T. Takenaka, H. Nagata, "Current status and prospects of lead-free piezoelectric ceramics". J. Eur. Ceram. Soc. 25 (2005) 2693–2700.

[3] M.D. Maeder, D. Damjanovic, N. Setter, "Lead Free Piezoelectric Materials". J. Electroceramics. 13 (2004) 385–392.

[4] Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, et al., "Lead-free piezoceramics". Nature. 432 (2004) 84.

[5] F. Rubio-Marcos, J.J. Romero, J.F. Fernández, P. Marchet, "Control of the Crystalline Structure and Piezoelectric Properties of (K,Na,Li)(Nb,Ta,Sb)O3 Ceramics through Transition Metal Oxide Doping". Appl. Phys. Express. 4 (2011) 101501.

[6] D.A. Ochoa, J.E. García, R. Pérez, V. Gomis, A. Albareda, F. Rubio-Marcos, et al., "Extrinsic contribution and non-linear response in lead-free KNN-modified piezoceramics". J. Phys. D. Appl. Phys. 42 (2009) 025402.

[7] J.G. Fisher, S.-J.L. Kang, "Microstructural changes in (K0.5Na0.5)NbO3 ceramics sintered in various atmospheres". J. Eur. Ceram. Soc. 29 (2009) 2581–2588.

[8] X. Vendrell, L. Mestres, "Optimization of the sintering conditions of the [(K0.5Na0.5)1-xLix]NbO3 system". Phys. Procedia. 8 (2010) 57–62.

Silicon Pulsed Laser Ablation in chloroform Kamal Abderrafi1, Raúl García-Calzada1, Juan F Sanchez-Royo1, Vladimir S Chirvony1, Saïd

Agouram2, Rafael Abargues3, Rafael Ibáñez1,* and Juan P Martínez-Pastor1,2 1 Instituto de Ciencias de los Materiales, Universidad de Valencia, PO Box 22085, 46071 Valencia, Spain

2 Dpt. Física Aplicada, Universidad de Valencia, Dr Moliner 50, 46100 Burjassot (Valencia), Spain 3 Intenanomat SL, C/Catedratico José Beltrán 2, 46980 Paterna (Valencia), Spain

*rafael.ibanez@uv.es

1. Introduction

Pulsed laser ablation of solid targets immersed in liquid (pulsed laser ablation in liquid, PLAL) is a rapidly growing technology, which enables the production of colloidal nanometre-sized particles. This method enables not only the formation but the functionalization of nanoparticles (NPs) by different ligands. [1–4]. On the one hand, the PLAL technique is commonly used to produce Si NPs, given the applications envisaged for Si quantum dots in photovoltaics. [5]

The size of Si QDs has a significant impact on their optical properties due to size confinement, multiexciton generation being the most important one [6]. On the other hand, the surface chemistry of semiconductor NPs, can lead to new functionalities (device patterning, catalysis, hydrogen storage, etc.) [7,8], other than new ink formulations.

Due to the relatively high energy of the laser beam a significant amount of solvent can be affected by pyrolytic processes, as it has been already reported in the case of Au NPs generation in toluene by using 9 ns 1064 nm pulses.[2] It was found more recently that PLAL of a Si target in ethanol with the use of 1064 nm excitation pulses of 10 ns [3] and 35–1000 fs [9] results in the formation of not only Si, but also of SiC nanocrystals.

2.- Summary We show, at this work, that a long-time laser ablation (40 ns, 355 nm laser pulses) of a Si target in chloroform (CHCl3) results in the formation of (i) multi-crystalline NPs composed of small (5–10 nm) Si and SiC mono-crystallites, (ii) multilayer graphite shells covering the multi-crystalline NPs and (iii) free carbon multilayer nanostructures (onion-like carbon or carbon nano-onions). On the basis of a comparison of the efficiency of formation of carbon nanostructures in CHCl3 versus CCl4 by laser ablation [1] and by ultrasound treatment reported in our previous work [10], we suggest that a chemical (solvent decomposition giving rise to highly reactive CH-containing radicals) rather than a physical (solvent atomization followed by carbon nanostructure formation) mechanism is responsible for graphitic shell formation. We have already described that a two-step process developed to produce small (a few nm) Si nanocrystals in colloidal suspension consisting of (1) a short-time (5 min) PLAL of a Si target in chloroform and (2) a long-time (60–90 min) ultrasound treatment of the suspension in the presence of HF that resulted in a disintegration of the initial big polycrystalline Si NPs to a few nm Si monocrystallites [10]. No carbon nanostructures were found in these NPs, most likely because the Si target was irradiated for a relatively short time that prevented secondary ablation of produced Si NPs. The first step on the chemical path for the formation of graphite nanostructures on Si NPs consists in the formation of radicals, [11]. These radicals reacts to form hydrocarbon polymers (as an intermediate product) and then forms graphite structures. An alternative preliminary hypothesis involves hydrogenation of the Si NP surface by hydrogen released due to thermal decomposition of CHCl3 followed by photochemical cleavage of the Si–H bond under illumination by 355 nm light pulses and an interaction of the formed Si dangling bonds with products of chloroform thermal decomposition. The process of graphitic shell formation under conditions of laser ablation in chloroform can be interesting for Si surface passivation, functionalization and protection.

Fig 1.:: Schematic synthetic pathway

Fig. 2: Scheme of the PLAL process in CHCl3. References [1] K. Abderrafi, R. García-Calzada, J. F. Sanchez-Royo, V. S. Chirvony, S. Agouram, R. Abargues, R.

Ibáñez, J. P. Martínez-Pastor, J. Phys. D. Appl. Phys. 2013, 46, 135301.

[2] V. Amendola, G. A. Rizzi, S. Polizzi, M. Meneghetti, J. Phys. Chem. B 2005, 109, 23125.

[3] S. Yang, W. Cai, H. Zeng, X. Xu, J. Mater. Chem. 2009, 19, 7119.

[4] S. Yang, H. Zeng, H. Zhao, H. Zhang, W. Cai, J. Mater. Chem. 2011, 21, 4432.

[5] P. Löper, D. Stüwe, M. Künle, M. Bivour, C. Reichel, R. Neubauer, M. Schnabel, M. Hermle, O. Eibl, S. Janz, M. Zacharias, S. W. Glunz, Adv. Mater. 2012, 24, 3124.

[6] D. Timmerman, J. Valenta, K. Dohnalová, W. D. A. M. de Boer, T. Gregorkiewicz, Nat. Nanotechnol. 2011, 6, 710.

[7] Y. Li, E. J. Lee, W. Cai, K. Y. Kim, S. O. Cho, ACS Nano 2008, 2, 1108.

[8] J. Zeng, F. Su, Y.-F. Han, Z. Tian, C. K. Poh, Z. Liu, J. Lin, J. Y. Lee, X. S. Zhao, J. Phys. Chem. C 2008, 112, 15908.

[9] P. G. Kuzmin, G. A. Shafeev, V. V. Bukin, S. V. Garnov, C. Farcau, R. Carles, B. Warot-Fontrose, V. Guieu, G. Viau, J. Phys. Chem. C 2010, 114, 15266.

[10] K. Abderrafi, R. García Calzada, M. B. Gongalsky, I. Suárez, R. Abarques, V. S. Chirvony, V. Y. Timoshenko, R. Ibáñez, J. P. Martínez-Pastor, J. Phys. Chem. C 2011, 115, 5147.

[11] M. Weissman, S. W. Benson, J. Phys. Chem. 1983, 87, 243.

[Se debe indicar en el encabezado si se trata de Comunicación Oral o Póster]

Síntesis y caracterización de circonato de bario dopado con cationes trivalentes

O. A. GERENA R.1, J.B. CARDA C.2 Y J.S. VALENCIA R.3 1. Escuela Colombiana de Carreras Industriales Bogotá, D.C., Colombia

2 Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón. España

3. Laboratorio de Catálisis Heterogénea, Departamento de Química, Universidad Nacional de Colombia–Sede Bogotá, Bogotá, D.C., Colombia

*ogerenar@ecci.edu.co Introducción

El circonato de bario es un material de gran interés por sus posibles aplicaciones en electrocerámicas, reactores nucleares, sensores entre otras en atención a su alto punto de fusión, estructura cristalina, baja reactividad química y estabilidad en ambientes tanto oxidantes como reductores. Se prepara de manera regular por el método cerámico que produce agregados heterogéneos y de grandes dimensiones. Como una alternativa de síntesis se usó el método citrato amorfo[1], que proporciona un medio homogéneo que permite controlar la estequiometría de la reacción, la pureza de fases, la textura y el tamaño de partícula.

Metodología.

El método de síntesis propuesto incluye la preparación de disoluciones acuosas de los cationes, su mezcla en una disolución de ácido cítrico, el ajuste del pH y, la eliminación del disolvente y la posterior calcinación a 800°C de los precursores antes obtenidos. Sel dopaje del circonato de bario se hizo en tres niveles 0.1, 0.2 y 0.3% con los cationes trivalentes. Lacaraterización se hizo por difracción de rayos X, microscopía electrónica de barrido, fotoluminiscencia y espectroscopías Raman y Uv-Vis

Conclusiones.

El análisis por difracción de rayos X (Figura 1) muestra que calcinando los precursores a 800°C se obtiene circonato de bario, indexado en el grupo espacial Pm-3m(221), Z= 1, sistema cristalino cúbico con parámetro de celda a=4.193Å y volumen de celda de 73,718 Å3; no se aprecian diferencias significativas debidas a la adición del catión dopante, debido al bajo porcentaje usado. Se evidencia la presencia de carbonato de bario y óxido de circonio que permanecen sin reaccionar a esta temperatura. Lo anterior se confirma por espectroscopía Raman (Figura 2) y por microscopía electrónica de barrido (Figura 3).

Figura 1 Difractograma de rayos X para el circonato de bario.

Figura 2Espectro Raman para circonato de bario.

Los análisis por microscopía electrónica de barrido permiten apreciar los cristales de carbonato de bario que permanecen sin reaccionar (Figura 3). Por medio de espectroscopía Uv-Vis, se determinaon los valores de band-gap para los sólidos preparados encontrando valores entre 3.8 y 4.4 eV, resultados que concuerdan con reportes de literatura. Los espectros de fotoluminiscencia (Figuras 4, 5 y 6) muestran cambios significativos en el ordenamiento de los cristales en función del contenido de agente dopante; el comportamiento general sugiere que se obtiene una estructura más ordenada cuando el porcentaje de dopaje es del 0,3% de lantánido trivalente.

[Se debe indicar en el encabezado si se trata de Comunicación Oral o Póster]

Figura 3 Micrografías BaZrO3 dopado con praseodimio.

Figura 4 Espectro de fotoluminiscencia para circonato de bario

Figura 5 Espectro fotoluminiscencia, BaZrO3 dopado con Lantano al 0.1, 0.2 y 0.3%.

Figura 6 Descomposición del espectro de fotoluminiscencia de BaZrO3 dopado con holmio

La descomposición del espectro de fotoluminiscencia muestra que ésta está conformada por un conjunto de tres señales, cuyas máximas intensidades se ubican en los 450nm (zona verde del espectro visible), 500 y 580nm (zona amarilla), el ajuste de la sumatoria de señales guarda una gran similitud con los datos obtenidos experimentalmente, tal como se aprecia en la Figura 4.8. Las dos primeras señales presentan intensidades bajas en comparación con la tercera. Agradecimientos Expresamos nuestro agradecimiento al profesor Elson Longo y su grupo de colaboradores, de la Universidad Federal de San Carlos, Estado San Pablo en Brasil; su ayuda fue fundamental en la consecución de los análisis para esta investigación.Los agradecimientos serán en el mismo formato que el texto. Referencias [1] Bhagwat, M. Synthesis of nanocrystalline zirconia by amorphous citrate route: structural and thermal (HTXRD) studies. Materials Research Bulletin 2004, 39, 1627–1640. (205) Cavalcante, L.; Anicetesantos, M.; Pontes, F.; Souza, I.; Santos, L.; Rosa, I.; Santos, M.; Santosjunior, L.; Leite, E.; Longo, E. Effect of annealing time on morphological characteristics of Ba(Zr,Ti)O3 thin films. Journal of Alloys and Compounds 2007, 437, 269–273. (226) Khan, Z.; Qureshi, M. Tantalum doped BaZrO3 for efficient photocatalytic hydrogen generation by water splitting. Catalysis Communications 2012, 28, 82–85. (227) Borja-Urby, R.; Diaz-Torres, L. a.; Salas, P.; Angeles-Chavez, C.; Meza, O. Strong broad green UV-excited photoluminescence in rare earth (RE=Ce, Eu, Dy, Er, Yb) doped barium zirconate. Materials Science and Engineering: B 2011, 176, 1388–1392. (228) Borja-Urby, R.; Díaz-Torres, L. a.; Salas, P.; Moctezuma, E.; Vega, M.; Ángeles-Chávez, C. Structural study, photoluminescence, and photocatalytic activity of semiconducting BaZrO3:Bi nanocrystals. Materials Science and Engineering: B 2011, 176, 1382–1387.

[Se debe indicar en el encabezado si se trata de Comunicación Oral o Póster]

(229) Borja-Urby, R.; Diaz-Torres, L. a.; Salas, P.; Vega-Gonzalez, M.; Angeles-Chavez, C. Blue and red emission in wide band gap BaZrO3:Yb3+,Tm3+. Materials Science and Engineering: B 2010, 174, 169–173. (230) Cavalcante, L. S.; Longo, V. M.; Zampieri, M.; Espinosa, J. W. M.; Pizani, P. S.; Sambrano, J. R.; Varela, J. a.; of very intense visible green photoluminescence in BaZrO3 powders. Journal of Applied Physics 2008, 103, 063527. (231) Moreira, M. L.; Glaucia, P.; Buzolin, C.; Longo, V. M.; Nicoleti, N. H.; Sambrano, J. R.; Li, M. S.; Varela, A.; Química, I. De; Paulista, U. E.; Box, P. O. Joint Experimental and Theoretical Analysis of OrderÀDisorder Effects in Cubic BaZrO 3 Assembled Nanoparticles under Decaoctahedral Shape. The Journal of physical chemistryJournal of physical chemistry 2011, 4482–4490. (233) Moreira, M. L.; Gurgel, M. F. C.; Mambrini, G. P.; Leite, E. R.; Pizani, P. S.; Varela, J. A.; Longo, E. Photoluminescence of Barium Titanate and Barium Zirconate in Multilayer Disordered Thin F R u † J u f y y A 2008 112 8938–8942. (234) Moreira, L.; Andre, J. Synthesis of Fine Micro-sized BaZrO3 Powders Based on a Decaoctahedron Shape by the Microwave-Assisted Hydrothermal & DESIGN 2009. 2009. (235) Yamanaka, S.; Hamaguchi, T.; Oyama, T.; Matsuda, T.; Kobayashi, S.; Kurosaki, K. H eat capacities and thermal conductivities of perovskite type BaZrO3 and BaCeO3. 2003, 359, 1–4. (236) Charrier-Cougoulic, I. Pagnier, T.; Lucazeau, G. Raman Spectroscopy of Perovskite-Type BaCex Zr1-xO3 (0<x>1). Journal of Solid State Chemistry 1999, 227, 220–227. (237) Yuan, Y.; Zhang, X.; Liu, L.; Jiang, X.; Lv, J.; Li, Z.; Zou, Z. Synthesis and photocatalytic characterization of a new photocatalyst BaZrO3. International Journal of Hydrogen Energy 2008, 33, 5941–5946. (238) Li, M.; Feng, Z.; Xiong, G.; Ying, P.; Xin, Q.; Li, C. Phase Transformation in the Surface Region of Zirconia Detected by UV Raman Spectroscopy. The Journal of Physical Chemistry B 2001, 105, 8107–8111. (239) Tiseanu, C.; Parvulescu, V. I.; Cojocaru, B.; Pemartin, K.; Sanchez-dominguez, M.; Boutonnet, M. In situ Raman and Time-Resolved Luminescence Investigation of the Local Structure of ZrO2 in the Amorphous to Crystalline Phase Transition. 2012. (240) Cavalcante, L. S.; Sczancoski, J. C.; Espinosa, J. W. M.; Mastelaro, V. R.; Michalowicz, a.; Pizani, P. S.; De Vicente, F. S.; Li, M. S.; Varela, J. a.; Longo, E. Intense blue and green photoluminescence emissions at room temperature in barium zirconate powders. Journal of Alloys and Compounds 2009, 471, 253–258. (241) Macario, L. R.; Mazzo, T. M.; Longo, E. Synthesis and photoluminescent proprieties of barium zirconate doped with Eu 3+11th International Conference on Advanced Materials; 2009; Vol. 3. (245) Moreira, M. L.; Volanti, D. P.; Andrés, J.; Montes, P. J. R.; Valerio, M. E. G.; Varela, J. a.; Longo, E. Radioluminescence properties of decaoctahedral BaZrO3. Scripta Materialia 2011, 64, 118–121. (246) Dias, A.; Ciminelli, V. S. T. Electroceramic Materials of Tailored Phase and Morphology by Hydrothermal Technology. 2003, 1344–1352. (247) Leonard, K. J.; Sathyamurthy, S.; Paranthaman, M. P. Characterization of BaZrO3 Nanoparticles Prepared by Reverse Micelle Synthesis. Chemistry of Materials 2005, 4010–4017. (248) Thongtha, A.; Bongkarn, T. Phase Formation and Microstructure of Barium Zirconate Ceramics Prepared Using the Combustion Technique. Ferroelectrics 2009, 383, 33–39.

Síntesis y caracterización de polímeros magnéticos.

Pablo Arévalo1, Josefa Isasi1,* y José Antonio Molina2 1. Dpto. de Química Inorgánica I, Universidad Complutense de Madrid, Avda Complutense s/n 28040, Madrid

2 Fundación Neurociencias y Envejecimiento. Emilio Carrere 7, 28015, Madrid. * e-mail: isasi@quim.ucm.es; tfno: +34 91 3945215

1. Introducción El interés por el estudio de los materiales híbridos se ha visto incrementado a lo largo de los años y han sido las enormes posibilidades de empleo ofrecidas por lo que se conoce como polímeros magnéticos, las que han forzado su demanda. Las investigaciones llevadas a cabo en este sentido se dirigen, hoy, hacia el desarrollo y la puesta a punto de nuevos métodos de preparación de polímeros magnéticos – núcleo asociado a un recubrimiento- en busca de su estabilidad, biocompatibilidad y biodegradabilidad [1]. En relación a la preparación de los núcleos magnéticos, se ha investigado ampliamente la obtención de espinelas inversas del tipo MFe2O4 constituidas por nanopartículas que muestran altos valores de la magnetización a la saturación (Ms) y un comportamiento superparamagnético. Son destacables los estudios realizados en magnetitas, Fe3O4, en los que se informa sobre la oxidación experimentada por estos óxidos de hierro para dar fases que contienen una mayor proporción de Fe3+, con especial influencia en el valor de la Ms y en el comportamiento magnético [2]. Estos problemas se evitan frecuentemente por sustitución en Fe3O4 de parte del Fe2+ por otros cationes divalentes de tamaño semejante. La oxidación y la agregación de las nanopartículas superparamagneticas también pueden prevenirse utilizando un recubrimiento que actué al mismo tiempo modificando las propiedades superficiales [3]. En este trabajo se exponen los resultados obtenidos en el aislamiento de nanocomposites de composición MFe2O4 (con M = Fe2+, Co2+, Ni2+) recubiertos de polietilenglicol y chitosán. Para su caracterización estructural se han empleado técnicas de difracción de rayos X (XRD), espectroscopia IR y microscopía electrónica de barrido y transmisión (SEM y TEM). 7. Agradecimientos Los autores agradecen a la Fundación Neurociencias y Envejecimiento (189/2012; 14/2013 y 177/2013) la financiación concedida para el desarrollo de este trabajo. Referencias [1] Ting-Yu L., Shang-Hsiu H., Dean-Mo L., San-Yuan C., I-Wei C., “Surface oxidation, size and shape of nano-

sized magnetite obtained by co-precipitation”. Nano Today, 4, (2009), 52-65. [2] I. Nedkova, T. Merodiiska, L. Slavov, R.E. Vandenberghe, Y. Kusano, J. Takada, “Biomedical nanoparticle

carriers with combined thermal and magnetic responses”. J. Magn. Magn. Mater., 300, (2006), 358-367. [3] H. Yin, H.P. Too, G.M. Chow, “The effects of particle size and surface coating on the cytotoxicity of nickel

ferrite”. Biomaterials, 26, (2005), 5818–5826.

Structural and magnetic study of new-layered oxygen deficient manganese oxides

Raquel Cortés-Gil1,2, Daniel González-Merchante1, M. Luisa Ruiz-González1, José M. Alonso3,

José L. Martínez4, and José M. González-Calbet1,*

1. Departamento de Química Inorgánica, Facultad de Químicas, Universidad Complutense, 28040-Madrid, Spain 2. CEI Campus Moncloa, UCM-Universidad Politécnica de Madrid, 28040-Madrid, Spain

3. Instituto de Magnetismo Aplicado, UCM-CSIC-ADIF, Las Rozas, P.O. Box 155, 28230-Madrid, Spain 4. Instituto de Ciencia de Materiales, CSIC, C/ Sor Juana Inés de la Cruz, 3, 28049-Madrid, Spain

*jgcalbet@ucm.es

Manganese related layered compounds belonging to the An+1BnO3n+1 Ruddlesden-Popper (RP) family (Fig. 1) has attracted much attention in the past two decades due to a variety of emerging phenomena such as magnetoresistance (MR), metal-insulator transition, magnetoelastic and magnetocaloric effects… involving intimate couplings of charge, orbital, spin and lattice degrees of freedom. These couplings result in a complex magnetic phase diagram of ferromagnetic (FM) as well as different antiferromagnetic (AFM) phases as a function of the doping level, x, and transition temperature [1]. Particular attention has been focused on the behaviour of La2-2xSr1+2xMn2O7 for x around 0.5, where the ground state changes from FM-conductor to AFM-insulator, being associated to a charge ordering (CO) state, in which Mn4+ holes are locked into a periodic array [2].

Figure 1. Structural models for RP series

Compositional variations at the anionic sublattice are scarce compared to other manganese related perovskite systems in which different superlattices have been described as a consequence of the ordering on non-occupied oxygen positions [3]. The RP structural type can admit oxygen deficiency for n=1, i.e., K2NiF4, affecting not only the transition metal oxidation states but also the magnetic and transport properties of these phases [4]. Nevertheless, not many studies have been focused to n= 2 RP [5], probably due to the difficulty to stabilize ordered RP members higher than n=1. In this sense, our objective has been to stabilize and characterize new perovskite related oxygen deficient phases in the La2-2xAE1+2xMn2O7- system (AE=Ca, Sr) where Mn in different oxidation states can coexist. Polycrystalline samples of LaSr2Mn2O7 and La0.5Ca2.5Mn2O7 composition were prepared using a conventional ceramic method. Reduced samples were synthesized in a Cahn D-200 electrobalance in order to precisely control the oxygen content. According to X-ray diffraction, selected area electron diffraction and high resolution transmission electron microscopy studies, the La2-2xAE1+2xMn2O7

topotactic reduction process has led to the stabilization of new La2-2xAE1+2xMn2O7-phases. Atomic resolution images of these compounds were obtained in a JEOL JEM ARM 200cFEG electron microscope. The microscope is dotted with an aberration corrector at the condenser lens allowing obtaining high annular dark field (HAADF) images with atomic resolution. In a HAADF image the contrast is usually referred to as Z-contrast imaging since the scattered intensity scales with the atomic number Z of the elements in the sample. Using this technique the presence of La and AE ordering as well as some order-disorder phenomena at atomic level has been evidenced. For instance, a characteristic HAADF image corresponding to La0.5Ca2.5Mn2O6.5 composition (figure 2) suggests, according to the atomic number of Ca (Z=20) and La (Z=57) (see model at the inset), the major presence of La at the perovskite block whereas Ca is at the rock-salt layers. Atomically resolved maps obtained by Electron Energy Loss Spectroscopy (EELS) confirm the above situation, as shown

n=1 n=2

PerovskiteABO3

Rock‐saltAO

AO(ABO3)n

n=1 n=2

PerovskiteABO3

Rock‐saltAO

AO(ABO3)n

in figure 2 b-f. In addition, contrast difference at the La positions are observed suggesting order disorder phenomena in this perovskite columns. Furthermore, EELS studies have allow identifying the presence of Mn in different oxidation states, depending on the oxygen content, in both Sr and Ca systems.

Figure 2. (a) HAADF image corresponding to La0.5Ca2.5Mn2O6.5. An schematic model for the cationic position has been inserted; (b) EELS spectra sum, acquired over the area marked in (a), showing the Ca-L2,3, Mn-L2,3 and La-M4,5 and signals; (c) HAADF image simultaneously recorded to EELS acquisition; (d) mapping obtained for the La-M4,5 signal (e) mapping obtained for the Ca-L2,3 signal; (f) mapping obtained for the Mn-L2,3 signal.

Magnetization and transport measurements in both systems indicate that they are indeed sensitive to the oxygen deficiency as observed in the corresponding magnetization and MR graphics for the Sr system (figure 3). Correlation of the observed behaviour with the different Mn oxidation states is in due course. a) b) Figure 3. (a) Magnetization vs temperature representation for La2-2xSr1+2xMn2O7- ( = 0, 0.5, 1); (b) MR vs magnetic field representation corresponding to La2-2xSr1+2xMn2O7- ( = 0, 0.05, 0.2). [1] C. D. Ling, J. E. Millburn, J. F. Mitchell, D. N. Argyriou, J. Linton, H. N. Bordallo, Phys. Rev. B 62, 15096, 2000. [2] D. N. Argyriou, H. N. Bordallo, B. J. Campbell, A. K. Cheetham, D. E. Cox, J. S. Gardner, K. Hanif, A. dos Santos, G. F. Strouse, Phys. Rev. B 61, 15269, 2000. [3] R. Cortes-Gil, M. Luisa Ruiz-González, J. M. Alonso, M. Vallet-Regí, A. Hernando, J. M. González-Calbet, Chem. Eur. J. 13, 4246, 2007. [4] H. J. Kitchen, I. Saratovsky, M. A. Hayward, Dalton Trans. 39, 6098, 2010. [5] H. El Shinawi, A Bertha, J. Hadermann, T. Herranz, B. Santos, J. F. Marco, F. J. Berry, C. Greaves, J. Sol. State Chem. 183, 1347, 2010.

-150000 -100000 -50000 0 50000 100000 150000-100

0

100

200

300

400

500

600

700

% M

R

H (Oe)

y = 7.00 y = 6.95 y = 6.80

T = 5 K

0 50 100 150 200 250 3000.000.250.500.751.001.251.501.75 0 50 100 150 200 250 3000.000

0.025

0.050

0.075

0.100

0.1250 50 100 150 200 250 300

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

y = 7.00

H = 1000 Oe

T (K)

M (

emu

/g) y = 6.50

y = 6.02

(c)

(f)

(e)

(d)

300 400 500 600 700 800 900

I (a

.u)

Energy Loss (eV)

(b)Ca‐L2,3

O‐K

Mn‐L2,3 La‐M4,5

Spectrum Image

Spatial Drift

5 nm

1.9 nm

0.39 nm

LaCaMn

(a)

(c)

(f)

(e)

(d)

300 400 500 600 700 800 900

I (a

.u)

Energy Loss (eV)

(b)Ca‐L2,3

O‐K

Mn‐L2,3 La‐M4,5

300 400 500 600 700 800 900

I (a

.u)

Energy Loss (eV)

(b)Ca‐L2,3

O‐K

Mn‐L2,3 La‐M4,5

Spectrum Image

Spatial Drift

5 nm

1.9 nm

0.39 nm

LaCaMn

(a)Spectrum Image

Spatial Drift

5 nm

1.9 nm

0.39 nm

LaCaMn

LaCaMn

(a)

Póster

Study of two new enamels as back contact for CIGS thin films by non-vacuum method

Diego Fraga1,*, Rafael Martí1, Iván Calvet1, Aitor Rey1, Ester Barrachina1, Teodora Stoyanova1 and Juan B. Carda1

1. Departamento de Química Inorgánica y Orgánica, Universitat Jaume I de Castellón *fraga@uji.es

1. Introduction The photovoltaic solar cells offer a limitless and environmentally friendly source of electricity. Nowadays, these devices are used for plenty of applications as it integration in urban areas (Building Integrated Photovoltaics, BIPV) [1]. For that purpose, the layer thickness is an essential part of the cells and can varies from a few nanometers to tens of micrometers. The technology based on thin film deposition of materials on substrate has an advantage to reduce significantly production costs keeping adequate solar conversion efficiencies [2-4]. The thin film solar cells combine very thin layers of photovoltaicly active material placed on variety of substrates like glass, metal or flexible polymers which opens a new dimension for novel applications [5]. However, an exhaustive search of previous art has not revealed any published or patented data that resemble the ceramic tile incorporation as a support for directly integrated photovoltaic solar cells. In this sense, we have developed ceramic photovoltaic tile that have objectives of reducing production costs and adding of mark- up to the final products. An introduction of this substrate give also an advantage of high temperature uses keeping the material thermal stability. The cell components are thin films (ohmic contact, p-type “absorber” and n-type “window”, antireflection layers), whose morphological characteristics determine the reliability and efficiency of the final device. In the present work, a new ceramic substrate covered previously by industrial ceramic glaze with gold or silver in its composition by non-vacuum method was developed. The glaze, an intermediate layer between CIGS layer and the substrate, provides chemical stability and roughness reduction, simulating glass surface with no porosity. In conclusion, we study the compatibility of the industrial ceramic glaze with the CIGS layer in order to obtain a back contact by non-vacuum process. References [1]. Gottschalg, R., et al., Influences on the energy delivery of thin film photovoltaic modules. Solar

Energy Materials and Solar Cells, 2013. 119: p. 169-180. [2]. Patrick Reinhard, A.C., Patrick Blosch, Fabian Pianezzi, Shiro Nishiwaki, Stephan Buecheler

and Ayodhya N. Tiwari, Review of Progress Toward 20% Efficiency Flexible CIGS Solar Cells and Manufacturing Issues of Solar Modules. IEEE JOURNAL OF PHOTOVOLTAICS, 2013. 3(1): p. 572-580.

[3]. Lee, D. and K. Yong, Non-vacuum deposition of CIGS absorber films for low-cost thin film solar cells. Korean Journal of Chemical Engineering, 2013. 30(7): p. 1347-1358.

[4]. Reinhard, P., S. Buecheler, and A.N. Tiwari, Technological status of Cu(In,Ga)(Se,S)2-based photovoltaics. Solar Energy Materials and Solar Cells, 2013. 119: p. 287-290.

[5]. Razykov, T.M., et al., Solar photovoltaic electricity: Current status and future prospects. Solar Energy, 2011. 85(8): p. 1580-1608.

Synthesis and Characterization of Eu(III)-Doped Hydroxyapatite: Photoluminescence Properties and Occupational Preferences

Thales Rafael Machado1,2, Elson Longo3, Héctor Beltrán-Mir2, Rolindes Balda4,5, Joaquín Fernández4,5,

Eloisa Cordoncillo2

1LIEC-Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Departamento de Química, UFSCar-Universidade

Federal de São Carlos,Rod.WashingtonLuis km 235, P.O. Box 676, 13565-905São Carlos, São Paulo, Brazil 2Departamento de Química Inorgánica y Orgánica, UJI-UniversitatJaume I,Avda. SosBaynat s/n, 12071 Castellón,

Spain 3LIEC-Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Instituto de Química, UNESP-Universidade

Estadual Paulista Júlio de Mesquita Filho, P.O. Box 355, 14801-907 Araraquara, São Paulo, Brazil 4Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Alda.Urquijo s/n, 48013 Bilbao, Spain 5 Centro de Física de Materiales CSIC-UPV/EHU and Donostia International PhysicsCenter, Apdo. 1072, 20080 San

Sebastián, Spain

Lanthanide-doped hydroxyapatite (HA) [Ca10(PO4)6(OH)2] has attracted attention for biomedical applications in the last years. The motivation to use this structure is due to its excellent biocompatibility, which comes from the similarities that present with the mineral component of hard tissues, and facility to incorporate many of the lanthanide species. Eu(III)-doped HA has attracted special attention and its use as biolabel and drug delivery system was proposed. Due to the strong crystal field of HA matrix, the Eu(III) luminescent centers exhibit peculiar photoluminescence characteristics. In this way, many natural and synthetic Eu(III)-containing apatites and their photoluminescence (PL) were studied. The PL strongly depends on the occupation of Eu(III) species into the distinct Ca(II) crystallographic positions and symmetries.This parameter can be changed by employing, for example, different heat treatment conditions. We report here a study on the luminescent and structural properties of as-synthetized and heat treated Eu(III)-doped HA samples obtained by the wet precipitation method. The heat treatment influence (slow cool or quenching) was studied in the samples to analyze the sites occupation of Eu(III) into the apatite structure. Results shown that Eu(III) species preferentially occupy the Ca(II)1 crystallographic position of HA structure at low temperature and the species partially migrate to the Ca(II)2 positions at high temperatures. However, the Eu(III) species are practically located at Ca(II)2 position when samples were quenched. In order to accomplish these studies, non-selective characterization using conventional fluorometer at room temperature and site-selective luminescent characterization with a rhodamine laser at liquid Helium (about 8K) were used. This is a pioneer work using these temperatures for Eu(III)-doped HA PL characterization. Furthermore, X-ray diffraction, Fourier infrared spectroscopy, energy-dispersive X-ray spectroscopy-coupled scanning electronic microscopy were also used.

1

Transesterificación de triacetilglicéridos con metanol sobre un catalizador MO/SiO2 (M= Sr)

Ana Medina1,*

, Jesús Valencia1,2

1,2

Univeridad Nacional de Colombia, Departamento de Química, Laboratorio de Catálisis Heterogénea, Grupo de Aplicaciones Fisicoquímicas del Estado Solido (AFES), Ciudad Universitaria, Transversal 38 No. 40-04, Bogotá, Colombia

*ajmedinar@unal.edu.co

1. Introducción

La transesterificación es una reacción que tiene lugar entre un ester de alto peso molecular (triacilglicerido) y un alcohol liviano (metano, etanol) para producir una mezcla de esteres y glicerol.

[1]Entre los materiales más promisorios para el desarrollo de esta reacción se hallan los

catalizadores heterogéneos sólidos, ácidos y /o básicos, nuevos materiales que posibilitan la separación del producto sin uso de disolventes, facilitan la regeneración y reciclaje del catalizador, la regulación del carácter corrosivo y la disminución de costos. Los óxidos de metales alcalinotérreos se utilizan como catalizadores heterogéneos sólidos básicos, estos presentan sitios de alta densidad electrónica, lo que los hace más reactivos en los sitios básicos de Lewis, generando mayor selectividad al ser empleados como catalizadores en la reacción de transesterificación de triacilgliceridos evitando las reacciones colaterales de saponificación y generando la recuperación parcial del catalizador empleado para tal fin.

[2]

Tomando en cuenta lo anterior, se preparó un catalizador sólido heterogéneo básico, basado en un óxido de estroncio soportado sobre una sílica mesoporosa del tipo de MCM 41. Los soportes de sílica estructurada se prepararon utilizando protocolos de síntesis hidrotérmica en presencia de Bromuro de hexadeciltrimetilamonio (CTAB) como director de estructura. Para tal efecto se modificaron algunas variables tales como la naturaleza del precursor de silicio, la temperatura del medio de reacción, el tiempo de reacción, y el tratamiento térmico del material

[3]. El soporte escogido para la preparación del

catalizador fue la MCM 3a, el cual presente el mejor comportamiento al ser calcinado a 650°C (Fig.1). Los catalizadores preparados de oxido de estroncio soportados sobre la sílica mesoporosa se trabajaron en dos cargas diferentes 9 y 16%

[4]. Estos sólidos se caracterizaron con técnicas como DRX, Fisisorción de

Nitrógeno a 77K (Fig. 2), TEM (Fig. 3), SEM y Raman. Los resultados mostraron que el catalizador SrO/MCM41 al 16% presenta un 93% de conversión de triolina hacia otros productos del biodiesel (Fig.4). Este comportamiento se atribuye a la carga depositada dentro del soporte lo cual contribuye a la formación y distribución de los sitios activos básicos dentro del catalizador.

Figuras

Fig. 2: Isotermas de adsorción- desorción de nitrógeno del catalizador SrO/MCM-41 (16%)

Fig. 1: Patrones de DRX de las muestras (a) SrO/MCM-41 (9%),(b) SrO/MCM-41 (16%) y (c) MCM-3a

2

Conclusiones

• El soporte seleccionado para los catalizadores (MCM-3a) presenta estructura hexagonal, grupo P6m, con parámetros de red a0 igual a 4,92 nm, área superficial de 726 m

2g

-1 y volumen de poro de 0,602

cm3g

-1.

• Los catalizadores de óxido de estroncio soportados sobre una sílica del tipo MCM-41 preparados por el método de impregnación y posterior tratamiento térmico, mostraron un comportamiento estable, conservando una fuerte interacción entre el SrO y la sílica, lo cual evito la lixiviación de los sitios activos en la fase metanolica de la reacción de transesterificación.

• El efecto del soporte (MCM-3a) sobre los catalizadores de SrO/MCM41 al 9% y 16% de carga de Sr, provocaron un aumento en el área superficial de cada uno de ellos, generando una mayor distribución del óxido de estroncio en la superficie y dentro de las cavidades tubulares del soporte, incrementando de esta forma los sitios activos básicos de los catalizadores, haciéndolos más eficaces en la reacción de transesterificación.

• El catalizador SrO/MCM-41 (16%) mostro las mejores conversiones de triglicéridos hacia otros productos del biodiesel.Las condiciones de reacción de la trioleína con metanol escogidas para el análisis de actividad catalítica resultaron ser las más adecuadas para obtener los mejores resultados en la transformación de triglicéridos a diglicéridos y monoglicéridos.

Agradecimientos

A la Universidad Nacional de Colombia- Sede Bogotá, a través del proyecto “Desarrollo de sistemas catalíticos basados en materiales cerámicos y biopoliméricos para la transformación de aceites vegetales” Código QUIPU 20501005406 financiado mediante la Convocatoria Bicentenario 2009 para proyectos de investigación.

Referencias

[1] M. C. G. Albuquerque, I. Jiménez-Urbistondo, J. Santamaría-González, J. M. Mérida-Robles, R. Moreno-Tost, E. Rodríguez-

Castellón, A. Jiménez-López, D. C. S. Azevedo, C. L. Cavalcante Jr and P. Maireles-Torres, Applied Catalysis A: General 2008, 334,

35-43.

[2] A. Corma and S. Iborra in Optimization of Alkaline Earth Metal Oxide and Hydroxide Catalysts for Base-Catalyzed Reactions,

Vol. Volume 49 Eds.: C. G. Bruce and K. Helmut), Academic Press, 2006, pp. 239-302.

[3] a) D. Kumar, K. Schumacher, C. du Fresne von Hohenesche, M. Grün and K. K. Unger, Colloids and Surfaces A:

Physicochemical and Engineering Aspects 2001, 187-188, 109-116; b) M. Grün, K. K. Unger, A. Matsumoto and K. Tsutsumi,

Microporous and Mesoporous Materials 1999, 27, 207-216.

[4] a) X. Liu, H. He, Y. Wang and S. Zhu, Catalysis Communications 2007, 8, 1107-1111; b) X. Liu, X. Piao, Y. Wang, S. Zhu and H.

He, Fuel 2008, 87, 1076-1082.

Fig. 3: TEM del catalizador SrO/MCM-41 (16%) Fig. 4: Concentración (mM) de mono-, di- y triglicéridos en relación

con el tiempo de reacción del catalizador SrO/MCM-41 (16%)

Er, Yb:NaY2F5O up-conversion nanoparticles: a new tool for lifetime thermometry in the biological

range Ol.A. Savchuk,1,* P. Haro-González,2 J.J. Carvajal,1 D. Jaque,2 J. Massons,1 M. Aguiló1, and F.

Díaz1 1. Física i Cristal·lografia de Materials i Nanomaterials (FiCMA-FiCNA)- EMaS, Universitat Rovira i Virgili (URV),

Campus Sescelades, C/ Marcel.li Domingo s/n, E-43007, Tarragona, Spain

2. Fluorescence Imaging Group, Departamento de Física de Materiales C-04 – Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, C/ Francisco Tomás y Valiente 7, E-28049, Madrid, Spain

*corresponding author: oleksandr.savchuk@urv.cat

Introduction Luminescent thermometry has attracted special attention in recent years, especially due to it’s

high spatial resolution and significant sensitivity. Moreover, the importance of luminescent thermometry in biomedical areas is enormous, since a variety of cellular events occured with temperature changes [1]. Lifetime-based luminescent thermometry offers advantages when compared to other luminescent approaches, since problems with movement, shading and light distribution of the sample can be eliminated [2]. Er3+ doped and Yb3+, Er3+ co-doped up-conversion systems have received a number of attention in bioimaging, displays application and nanothermometry [3-4], since they present the ability to be pumped in the near infrared and emit in the visible. In 2010 Vetrone et al. showed that fluorescent Er,Yb:NaYF4 nanoparticles can be successfully used as nanothermometers measuring temperature changes in individual cancer cells up to their thermally induced death [5], for instance.

In this work we present the comparison of temperature dependent fluorescent lifetime at the biological range of Er,Yb:NaYF4 and Er,Yb:NaY2F5O nanoparticles. Er,Yb:NaY2F5O nanocrystals show great potentiality as thermal sensors at the nanoscale for biomedical applications due to the incorporation of additional non-radiative relaxation mechanisms that shorten the emission lifetime generated by the oxygen present in the structure. Here we report ex-vivo temperature determination by laser induced heating in chicken breast using lifetime-based thermometry in these up-conversion nanoparticles.

Experimental section Fluorescence lifetime of Er,Yb:NaYF4 and Er,Yb:NaY2F5O nanoparticles was measured by

exciting the samples with an optical parametric oscillator (Opotek Vibrant HE 355 II+UV) at 980 nm with a pulse duration of 6 ns and a repetition frequency of 10 Hz. The fluorescent light emitted from the samples was collected with objectives, transferred to the monochromator for selection of specific wavelengths, and finally detected using a Hamamatsu R928 photomultiplier. The decay of the signal was measured as a function of time with a digital oscilloscope. Data was transferred to a computer for later analysis.

For the lifetime thermal sensing calibration, Er,Yb:NaYF4 and Er,Yb:NaY2F5O nanoparticles were introduced in to Linkam THMS 600 heating stage. For ex-vivo temperature determination, an aqueous solution containing luminescent up-conversion nanoparticles was injected into a μ-channel and placed into a chicken breast. Then, the chicken breast with μ-channel inside was illuminated simultaneously with two laser beams in a double beam confocal microscope. The heating laser, emitting at 1090 nm was focused into the channel using objectives. In order to prove the thermal sensing system based on lifetime measurements, a second laser with emission at 980 nm was focused on the top of the channel, spatially overlapping with the heating spot. The generated fluorescence by nanoparticles was collected by the same objective and after passing filter was focused into a multiplier tube connected to a digital oscilloscope.

Results We studied the temperature dependent fluorescence lifetime of Er,Yb:NaYF4 and

Er,Yb:NaY2F5O nanoparticles in the biological range of temperatures (25 – 60 ºC). In both cases with increasing temperature, the lifetime emission decay rate became faster. However, the shortening of the decay time in Er,Yb:NaY2F5O nanoparticles is more evident (see Fig. 1a). The observed temperature induced lifetime reduction is a consequence of the activation of phonon-assisted processes and of multiphonon decays driven by temperature increments. Temperature-dependent

normalized lifetime decreased almost linearly with temperature. In order to have a practical indicator of temperature using lifetime measurements, it is highly desirable to have a linear dependence with temperature since it simplifies the calibration of the system. Thus, in this case we have excellent temperature sensors, especially in the case of Er,Yb:NaY2F5O nanoparticles where the slope of the linear fit is higher (see Fig. 1b). In order to demonstrate the potentiality of lifetime thermometry using up-conversion nanoparticles, we have performed an ex vivo temperature determination experiment in chicken breast that was heated by an additional laser beam. Er,Yb:NaY2F5O nanoparticles were dispersed in water, and injected into a fresh chicken breast within a depth of 1 mm. The clear evolution of the lifetime indicated the progressive heating of the tissue surrounding the nanoparticles by the effect of the increasing power of the 1090 nm laser. These data were used to determine the temperature inside the chicken breast, the sub-tissue temperature, as a function of the laser heating power.

Figure 1. (a) Fluorescence decay curves of the 545 nm emission line of Er,Yb:NaY2F5O nanoparticles at 25 and 60 ºC, and (b)

normalized lifetime values as a function of temperature.

Conclusion In conclusion, we have reported ex-vivo temperature determination based on fluorescence

lifetime using up-conversion nanoparticles. Ex-vivo temperature measurements were in a good agreement with theoretical predictions showing the potentiallity of Er,Yb:NaY2F5O nanoparticles as lifetime-based thermometers.

Acknowledgements This work was supported by the Spanish Government under projects No. MAT2011-29255-

C02-02 and TEC2010-21574-C02-02, the Catalan Government under project No. 2009SGR235, and the European Commission within the Seventh Framework Program under project No. FP7-SPA-2010-263044. O.A. Savchuk is supported by Catalan Government through the fellowship 2013FI_B 01032.

References [1]. B. Hildegrandt, P. Wust, O. Ahlers, A. Dieing, G. Sreenivasa, T. Kerner, R. Felix, H. Riess, “The cellular and molecular basis of hyperthermia”. Crit. Rev. Oncol. Hemat., 43 (2002) 33-56. [2]. P. Haro-Gonzalez, L. Martinez-Maestro, I. R. Martin, J. Garcia-Sole, and D. Jaque, “High sensitivity fluorescence lifetime thermal sensing based on CdTe quantum dots”. Small, 8, 17, (2012), 2652-2658. [3]. Nikifor Rakov, Glauco S. Maciel, “Three photon upconversion and optical thermometry characterization of Er3+:Yb3+ co-doped yttrium silicate powders”. Sensors and Actuators B, 164 (2012), 96-100. [4]. Lorenz H Fischer, Gregory S. Harms, and Otto S. Wolfbeis, “Upconverting nanoparticles for nanoscale thermometry”. Angew. Chem. Int. Ed. 50, (2011), 4546-4551. [5]. F. Vetrone, R. Naccache, A. Zamarron, A. Juarranz de la Fuente, F. Sanz-Rodriguez, L. M. Maestro, E. M. Rodriguez, D. Jaque, J. G. Sole, and J. A. Capobianco, “Temperature sensing using fluorescent nanothermometers”. ACS Nano 4, 6, (2010), 3254-3258.

[Póster]

Up-converting nanooxides for functional glazes Francisco Gonell, María Sospedra, Beatriz Julián-López*

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Castellón, Spain. *e-mail: julian@uji.es

Ceramic industry is one of the most dynamic sectors in the Spanish economy that requires the development of new functional materials to ensure their permanence in an increasingly global and competitive system. We can currently find in the market ceramic products able to decompose NOx from air, to keep the warmth of the climate, or even superhydrophilic self-cleaning glazes. Despite the remarkable progress achieved in the last decade, nanomaterials and nanotechnology offers immense opportunities to develop smart functional glazes.

In this context, our group is working to provide new functionalities to ceramic glazes by means of incorporating nanooxides with up-converting properties. Up-conversion of infrared (IR) photons into visible radiation constitutes a promising approach to prepare smart glazes with application in security, sensors or even for light harvesting systems [1]. The most studied up-conversion systems to date involve rare-earth (Er, Yb) doped fluoride based materials[2,3], featuring high quantum efficiencies. However, these materials are affected by some important drawbacks as their toxicity, limited chemical and thermal stability and high cost, mainly related to the complex synthetic procedures involved. Alternatively, up-conversion systems based on metal oxides are characterized by their excellent synthetic and morphological versatility, which allows the fine tuning of the optical properties. Furthermore, the use of up-converting nanooxides represents low-cost photonic nanomaterials that can also be applied in ceramic ink-jet technologies.

This work reports the study of nanooxides, ZrO2 and Y2O3, doped with Er3+, Yb3+ and Tm3+ ions that have been prepared via Soft Chemistry methodologies. These synthetic approaches allow the control of the morphology and size of the materials. Furthermore, the nature and concentration of lanthanide ions was chosen in each case to tune the emission properties according to the well-established up-conversion mechanisms.

The crystalline structure, morphology and optical properties of these materials were analyzed by the adequate techniques (XRD, SEM, HRTEM, vibrational spectroscopy, spectrophotometry and laser spectroscopy). Nanoparticles with sizes ranging from 20 to 400 nm and different morphologies (spherical, platelets…) were obtained. All these materials exhibited emitting properties in the blue, green and red region upon excitation with a 980 nm-laser diode of 40mW. The relationship between the crystalline structure, the annealing temperature and the intensity of the emissions was studied (Figure 1).

Figure 1. (left) SEM micrograph of Er,Yb-Y2O3 nanospheres (bar is 1 μm). (center) Up-conversion RT emission spectra of the Er 5%/Yb5% (black) and Er 5%/Yb10% (blue) - Y2O3 nanospheres upon excitation at 980 nm. (right) Picture showing the green,

red and blue emissions of different lanthanide-doped nano-oxides upon excitation with 980 nm.

The chemical stability of these nanomaterials in commercial ceramic glazes was tested, and different results were obtained depending on the size of the particles and the composition of the glaze. The materials with low diameter size can be easily dispersed in aqueous media and can be envisaged for ink-jet printing technologies. The results obtained in this work are relatively close for a real technological deployment.

[Póster]

Acknowledgments Financial support from the Spanish Government (Ministerio de Economía y Competitividad: MAT2011-27008 project) is acknowledged. F. Gonell thanks Ministerio de Educación y Ciencia for his PhD fellowship. Serveis Centrals d’Instrumentació Científica (SCIC, UJI) is also acknowledged for equipment facilities. References [1] M. Haase, H. Schafer, Angewandte Chimie Int. Ed. 50 (2011), 5808. [2] K. W. Krämer, D. Biner, G. Frei, H. U. Güdel, M. P. Hehlen, S. R. Lüth, Chem. Mater. 16 (2004), 1244. [3] F. Wang, X. Liu, J. Am. Chem. Soc. 130, (2008), 5642.

Upconversion processes and light color selection in Yb-sensitized Pr-doped fluoride-based

hydrothermal nanoparticles

Concepción Cascales* and Carlos Zaldo Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, c/ Sor Juana Inés de la Cruz 3,

E-28049 Madrid, Spain *ccascales@icmm.csic.es

Research on trivalent lanthanide (Ln3+)-based micro/nano upconverting particles (Ln-UCPs) is nowadays stimulated by their successful exploitation in fields related to security, imaging and sensing, which include uses as selective biological probes and cellular thermometers, and in lighting technologies, namely for color displays and in the development of white light sources. The advancement of such applications is supported by both the availability of inexpensive near-infrared (NIR) diode lasers (DL) as excitation sources, and by the current development of effective chemical routes to produce micro/nano Ln-UCPs. Moreover, any of the above practical purposes requires high luminescence efficiency from Ln-doped UC materials. This need can be satisfied in matrices with low phonon energies, which minimize multiphonon de-excitation probabilities, and thus non-radiative relaxations. From this point of view, oxyhalide- and halide-based hosts, whose cut-off phonon energies are typically lower than oxides, are interesting UC systems.

In this work we study the room-temperature UC luminescence of Yb3+-sensitized Pr3+-doped samples of Y6O5F8, β-NaYF4 and YF3 under NIR DL excitation.

Yb3+ (2 mol %)-sensitized Y6O5F8, β-NaYF4 and YF3 particles doped with Pr3+ (0.2 up to 2 mol %) have been prepared by hydrothermal syntheses carried out at 185 ºC during 24 h, under autogenous pressure, see SEM and TEM images in Figure 1. Under ∼978 nm diode laser excitation the upconverted light emitted by these samples presents different spectral distribution (see Figure 2 for 0.2 mol% Pr3+ doped samples), which has been explained in each case through specific pathways for populating 3P2, 3P1(+1I6), 3P0 and 1D2 emitting levels. Whereas only green to bluish-green upconversion emissions are achieved with Pr-doped Yb:β-NaYF4 and Yb:YF3 fluorides, Pr-doped Yb:Y5O6F8 oxyfluoride allows the selection of the color of the upconverted light through the control of the Pr3+ concentration and by the excitation power density.

Fig.1. Images of Yb-sensitized Pr-doped fluoride-based hydrothermal samples: a) SEM micrograph of micron-sized bundles of Y6O5F8, and TEM views of: b) individual nanotubes that constitute the bundles of Y6O5F8, c) Nanoparticles of β-NaYF4, d) Nanoparticles of YF3.

Fig.2. Room temperature upconversion spectra under diode laser excitation at ∼978 nm with 350 W·cm-2 power density of Yb-sensitized (2 mol%) Pr-doped (0.2 mol%) samples: a) Y6O5F8, b) β-NaYF4, c) YF3.

Acknowledgement: This work was supported by the Spanish Ministry of Economy and Competitiveness under project MAT2011-29255-C02-01.

500 600 700 800

UC

INTE

NS

ITY

(arb

. u.) Pr, Yb:Y6O5F8

b) Pr, Yb:β-NaYF4

a)

WAVELENGHT (nm)

c) Pr, Yb:YF3

120 nm

b)

150 nm

40 µm

a)

120 nm

c)

d)

Variable-temperature IR spectroscopy for ranking Brønsted acidity

Montserrat Rodriguez Delgado*, Carlos Otero Arean Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca, Spain

*montserrat.rodriguez@uib.es 1. Introduction Solid acids having a large specific surface area, such as protonic zeolites and related porous solids, are often used as catalysts in a wide range of chemical processes, which span the petrochemical industry, methanol to olefin conversion and the production of fine chemicals, to quote some of the most common examples. The strength of their catalytically active Brønsted-acid sites is a main factor determining performance of such porous solids; hence the need of having a reliable method to rank surface acidity of solid acids.

However, at variance with aqueous acid solutions for which the corresponding pKa provides a quantitative measure of acid strength, no clear-cut measurement has yet been found for solid acids. The most common method currently being used relies on adsorption of a weak base (such as CO or dinitrogen) which forms hydrogen-bonded OH···CO (or OH···NN) adsorption complexes with the Brønsted-acid hydroxyl groups of the solid. The adsorption complex can easily be monitored by IR spectroscopy as hydrogen bonding brings about a distinctive bathochromic shift, Δν(OH), of the O−H stretching mode of the hydroxyl group. The magnitude of Δν(OH) (for any given weak base) is taken to be an indicator of relative Brønsted acidity when ranking solid acids [1]. The question, however, arises as to whether Δν(OH) really correlates with acid-base interaction energy or not. We report herein on recent studies showing that such a correlation cannot be taken for granted. 2. Methods and results Adsorption of CO and dinitrogen on several protonic zeolites belonging into different structural groups was studied by means of variable-temperature IR (VTIR) spectroscopy [2] (which affords simultaneous determination of Δν(OH) and standard adsorption enthalpy, ΔH0) and adsorption calorimetry. As an example, results obtained for CO adsorption on H-FER and H-MCM-22 (MWW structure type) are given in Figures 1 and 2. Corresponding results for other protonic zeolites (some of them taken from the published literature) are summarized in Table 1.

3000320034003600

-0,3

-0,2

-0,1

0,0

0,1

0,2

0,3

-2

0

2

4

4,0 4,5 5,0 5,5 6,0

98

76

5432

98765432

Abs

orba

nce

Wavenumber / cm-1

3605

1

1

A(OH) = -297 cm-1

H0 = -28,4 kJ mol-1

1000/T (K-1)

ln {

/[(1-)p

]}

3000310032003300340035003600

-0,2

-0,1

0,0

0,1

0,2

-4

-3

-2

-1

0

4,5 5,0 5,5 6,0

B

1110

1110

987654

32

9876

5

432

Abs

orba

nce

Wavenumber / cm-1

3625

1

1

(OH) = -320 cm-1

H0 = -22,5 kJ mol-1

ln {

/[(1-)p

]}

1000/T (K-1)

Fig. 1: (A) Representative variable-temperature IR spectra (O−H stretching region) of CO adsorbed on H-FER. From 1 to 9, temperature goes from 167 to 224 K; and equilibrium pressure from 0.57 to 1.75 mbar. (B) Representative variable-temperature IR spectra (O−H stretching region) of CO adsorbed on H-MCM-22. From 1 to 11, temperature goes from 154 to 214 K; and equilibrium pressure from 6.52 to 9.24 mbar. The spectra are shown in the difference mode (zeolite blank subtracted). Insets show the corresponding van’t Hoff plots.

Fig. 2: Adsorption heat of CO on H-FER (squares) and H-MCM-22 (circles) measured by calorimetry at 303 K, as a function of coverage. 3. Discussion and Conclusions Experimental results summarized in Table 1 clearly show that while for some protonic zeolites (H-Y, H-FER and H-ZSM-5) there is a direct correlation between standard adsorption enthalpy (ΔH0) and bathochromic shift (Δν(OH)) of the O−H stretching mode in the corresponding hydrogen-bonded (OH···CO) adsorption complex, the same does not hold in the case of other zeolites. Thus, MWW structure-type zeolites show a distinctively lower (absolute) value of ΔH0 (for CO adsorption) than H-FER and H-ZSM-5; and yet the (absolute) value of Δν(OH) (after hydrogen bonding with the probe molecule) is significantly larger for the protonic zeolites of the MWW group. Measurements performed by using dinitrogen as the probe molecule confirmed the results obtained with CO, in the sense that a direct correlation between Δν(OH) and ΔH0 was not always observed. Taken as a whole, the obtained results clearly show that the usual practice of ranking Brønsted-acid strength of solids by their O−H frequency shift probed by and adsorbed weak base can be misleading. Determination of the enthalpy change involved in formation of the corresponding hydrogen-bonded adsorption complex seems to be a more reliable instrumental method. References [1] E.A. Paukshtis, E.N. Yurchenko. Russ. Chem. Rev., 52, (1983), 242. [2] E. Garrone, C. Otero Arean. Chem. Soc. Rev., 34, (2005), 846. [3] C.O. Arean. J. Mol. Struct., 880, (2008), 31. [4] P. Nachtigall, O. Bludsky, L. Grajciar, D. Nachtigallova, M.R. Delgado, C.O. Arean. Phys. Chem. Chem.

Phys., 11, (2009), 791.

Table 1. Experimental data for CO hydrogen bonding in protonic zeolites.

Zeolite Structure type

-Δν(OH) (cm-1)

-ΔH0 (kJ mol-1) Ref.

H-Y FAU 275 25.6 [3]

H-ZSM-5 MFI 303 29.4 [3]

H-FER FER 297 28.4 [4]

H-MCM-22 MWW 320 22.5 This work

H-MCM-56 MWW 316 20 This work

0,00 0,05 0,10 0,15 0,200

5

10

15

20

25

30

H-FER H-MCM-22 first run H-MCM22 second run

Qdi

ff (kJ

mol

-1)

Coverage ()

Y-splitter and Mach-Zehnder interferometer on RbTiOPO4 by Cs

+ ion Exchange

M.A. Butt1, R. Solé

1, M.C. Pujol

1, A. Ródenas

1, G. Lifante

2, J.S. Wilkinson

3, M. Aguiló

1 and F.

Díaz1

1. Física i Cristal·lografia de Materials i Nanomaterials (FiCMA-FiCNA) and EMaS, Universitat Rovira i Virgili (URV), Marcel·lí Domingo s/n, E-43007 Tarragona, Spain

2. Departamento de Física de Materiales, Universidad Autónoma de Madrid 28049 Madrid, Spain

3. Optoelectronics Research Centre, University of Southampton, Southampton, SO171BJ, United Kingdom

* mariacinta.pujol@urv.cat, rosam.sole@urv.cat

1. Introduction

KTiOPO4 (KTP) and its isostructural RbTiOPO4 (RTP) are well known for their interesting properties for non-linear optical applications. They crystallize in the noncentrosymmetric orthorhombic space group Pna21 [1]. RTP has similar nonlinear optical coefficients than KTP [2], a higher laser damage threshold (~2 times larger than the one of KTP) [3, 4], a wide range of wavelength and angular acceptance for frequency doubling, high chemical stability, and low photorefractive damage susceptibility [5]. RTP has a higher damage threshold than LiNbO3 (LN); despite of this disadvantage, LN is broadly used for integrated optics (IO) [6, 7]. RTP is a promising candidate for various IO electro-optical (E-O) applications such as modulators and Q-switches because of its large electro-optical coefficients and low dielectric constants. Recently, Cs+ ion exchange channel waveguides on RTP has been reported [8]. Cs+ ions were used for diffusion process because it produces an increase in the refractive index and its ionic radius is not far from the Rb+ radius. The motivation of the current work is to make use of diffusion process for fabricating some IO E-O devices like Y-splitters and Mach-Zehnder interferometers (MZI) on RTP (001) substrates. In this work, we are reporting the Cs+ ion exchange splitters and MZI on RTP (001).

2. Experimental details

A Ti layer with 200 nm thickness was deposited on the RTP (001) substrate with the help of the sputtering technique. The designs of Y-splitters and MZI of 9 mm in length and 6 microns in width along b crystallographic direction were transferred on a photoresist with the help of conventional photolithography. After developing the exposed part, the design was transferred to the Ti mask by etching it with H2O2:NH4OH in 2:1 molar ratio. Cs+ diffusion was obtained by immersing the sample with Ti pattern horizontally in a crucible containing 25 g of CsNO3 at 698 K for 2 h at 40 rpm. The end facets of the channels were polished to optical grade quality. Vertically polarized 1520 nm laser light was used to characterize the waveguide structures. We have recorded the guiding of 1520 nm light with the help of an IR camera, for MZI and Y –splitters.

3. Results and discussion

Ti is used as a hard mask as it shows a good adhesion on RTP substrates and can sustain a Cs+ diffusion temperature of 698 K. After the diffusion process, the Ti hard mask is removed with diluted HF acid. Cs+ diffusion is straight along c crystallographic direction due to the almost unidirectional ionic conductivity character of the material, due to the presence of Rb+ channels along this direction [9].The graded refractive index profile was measured in [8], and we can expect a graded refractive index change region till 20 micron depth. EPMA analysis show traces of Cs+ element along c direction till 6 microns. In all the MZI and Y-splitters the 1520 nm light was guided in TM polarization. Figure 1 shows the horizontal intensity cross section (a) and the measured near field pattern (b) of the output guided modes in a 9 mm long Y-splitter. A Gaussian profile with dimensions of 15.6 µm x 9.0 µm for the left arm and 13.2 µm x 8.5 µm for the right arm in the b and c direction respectively was measured.

Fig. 1: a) Horizontal intensity cross section of the near field profile and b) measured near-field image, of the fundamental mode at 1520 nm wavelength of a Y-splitter.

4. Conclusions

Cs+ ion exchange RTP Y-splitters and MZI have been reported for the first time to our knowledge. The Cs+ diffusion is parallel to c crystallographic direction and produces a high refractive index contrast in nz.

5. Acknowledgments

This work was supported by the Spanish Government under Projects MAT2011-29255-C02-02, TEC2010-21574-C02-01, TEC2010-21574-C02-02, by the Catalan Authority under Project 2009SGR235 and by the European Union under Project No. FP7-SPA-2010-263044. M. Ali Butt thanks the Catalan Government for the FI-DGR fellowship 2012FI-B 00192.

References

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