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Lee Y.,Brown University | Garcia M.A.,CSIC - Institute of Ceramics and Glass | Frey Huls N.A.,Brown University | Sun S.,Brown University
Angewandte Chemie - International Edition | Year: 2010

("Figure Presented") Dumbbell-like Au-Fe3O4 nanoparticles and their single-component counterparts, Au and Fe 3O4, were compared regarding their H2O 2 reduction capability. The Au-Fe3O4 nanoparticles are catalytically more active, which is attributed to polarization effects from Au to Fe3O4. This activity can be further tuned by the size of the nanoparticles. © 2010 Wiley-VCH Verlag GmbH &. Co. KGaA,.

Moreno R.,CSIC - Institute of Ceramics and Glass
Advances in Applied Ceramics | Year: 2012

Colloidal processing has demonstrated its suitability to produce complex shaped ceramics and ceramic-metal composites with tailored microstructure. By combining different shaping methods, it is possible to produce complex three-dimensional bodies as well as single or multilayer coatings, self-sustaining films and laminates. This work summarises the main features of colloidal processing, including colloidal stability and stabilisingmechanisms focusing the importance of the rheological behaviour in the shaping step. The most common shapingmethods and consolidationmechanisms based on suspensions are presented as well as their capabilities for producing composites with complex shapes and microstructures. © 2012 Institute of Materials.

Moure C.,CSIC - Institute of Ceramics and Glass | Pena O.,CNRS Chemistry Institute of Rennes
Progress in Solid State Chemistry | Year: 2015

The perovskite structure is one of the most wonderful to exist in nature. It obeys to a quite simple chemical formula, ABX3, in which A and B are metallic cations and X, an anion, usually oxygen. The anion packing is rather compact and leaves interstices for large A and small B cations. The A cation can be mono, di or trivalent, whereas B can be a di, tri, tetra, penta or hexavalent cation. This gives an extraordinary possibility of different combinations and partial or total substitutions, resulting in an incredible large number of compounds. Their physical and chemical properties strongly depend on the nature and oxidation states of cations, on the anionic and cationic stoichiometry, on the crystalline structure and elaboration techniques, etc. In this work, we review the different and most usual crystalline representations of perovskites, from high (cubic) to low (triclinic) symmetries, some well-known preparation methods, insisting for instance, in quite novel and original techniques such as the mechanosynthesis processing. Physical properties are reviewed, emphasizing the electrical (proton, ionic or mixed conductors) and catalytic properties of Mn- and Co-based perovskites; a thorough view on the ferroelectric properties is presented, including piezoelectricity, thermistors or pyroelectric characteristics, just to mention some of them; relaxors, microwave and optical features are also discussed, to end up with magnetism, superconductivity and multiferroïsme. Some materials discussed herein have already accomplished their way but others have promising horizons in both fundamental and applied research. To our knowledge, no much work exists to relate the crystalline nature of the different perovskite-type compounds with their properties and synthesis procedures, in particular with the most recent and newest processes such as the mechanosynthesis approach. Although this is not intended to be a full review of all existing perovskite materials, this report offers a good compilation of the main compounds, their structure and microstructure, processing and relationships between these features. © 2015 Elsevier Ltd. All rights reserved.

Carrodeguas R.G.,CSIC - Institute of Ceramics and Glass | De Aza S.,CSIC - Institute of Ceramics and Glass
Acta Biomaterialia | Year: 2011

Nowadays, α-tricalcium phosphate (α-TCP, α-Ca 3(PO 4) 2) is receiving growing attention as a raw material for several injectable hydraulic bone cements, biodegradable bioceramics and composites for bone repair. In the phase equilibrium diagram of the CaO-P 2O 5 system, three polymorphs corresponding to the composition Ca 3(PO 4) 2 are recognized: β-TCP, α-TCP and α′-TCP. α-TCP is formed by heating the low-temperature polymorph β-TCP or by thermal crystallization of amorphous precursors with the proper composition above the transformation temperature. The α-TCP phase may be retained at room temperature in a metastable state, and its range of stability is strongly influenced by ionic substitutions. It is as biocompatible as β-TCP, but more soluble, and hydrolyses rapidly to calcium-deficient hydroxyapatite, which makes α-TCP a useful component for preparing self-setting osteotransductive bone cements and biodegradable bioceramics and composites for bone repairing. The literature published on the synthesis and properties of α-TCP is sometimes contradictory, and therefore this article focuses on reviewing and critically discussing the synthetic methods and physicochemical and biological properties of α-TCP-based biomaterials (excluding α-TCP-based bone cements). © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Garcia M.A.,CSIC - Institute of Ceramics and Glass | Garcia M.A.,IMDEA Madrid Institute for Advanced Studies
Journal of Physics D: Applied Physics | Year: 2011

The excitation of surface plasmons (SPs) in metallic nanoparticles (NPs) induces optical properties hardly achievable in other optical materials, yielding a wide range of applications in many fields. This review presents an overview of SPs in metallic NPs. The concept of SPs in NPs is qualitatively described using a comparison with simple linear oscillators. The mathematical models to carry on calculations on SPs are presented as well as the most common approximations. The different parameters governing the features of SPs and their effect on the optical properties of the materials are reviewed. Finally, applications of SPs in different fields such as biomedicine, energy, environment protection and information technology are revised. © 2011 IOP Publishing Ltd.

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