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Size and Composition Effects in the Structure and Properties of Polymer-Protected Bimetallic Particles

Published online by Cambridge University Press:  17 March 2011

Marie-José Casanove
Affiliation:
Centre d'Elaboration de Matériaux et d'Etudes Structurales, CNRS, B.P. 4347, F-31055 Toulouse cedex 4, France
Pierre Lecante
Affiliation:
Centre d'Elaboration de Matériaux et d'Etudes Structurales, CNRS, B.P. 4347, F-31055 Toulouse cedex 4, France
Marie-Claire Fromen
Affiliation:
Centre d'Elaboration de Matériaux et d'Etudes Structurales, CNRS, B.P. 4347, F-31055 Toulouse cedex 4, France
Marc Respaud
Affiliation:
Laboratoire de Physique de la Matière Condensée, INSA, F-31077 Toulouse cedex 4, France
David Zitoun
Affiliation:
Laboratoire de Chimie de Coordination, CNRS, F-31077, Toulouse cedex 4, France
Cheng Pan
Affiliation:
Laboratoire de Chimie de Coordination, CNRS, F-31077, Toulouse cedex 4, France
Karine Philippot
Affiliation:
Laboratoire de Chimie de Coordination, CNRS, F-31077, Toulouse cedex 4, France
Catherine Amiens
Affiliation:
Laboratoire de Chimie de Coordination, CNRS, F-31077, Toulouse cedex 4, France
Bruno Chaudret
Affiliation:
Laboratoire de Chimie de Coordination, CNRS, F-31077, Toulouse cedex 4, France
Fabrice Dassenoy
Affiliation:
Fritz Haber Institüt, Berlin, Germany
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Abstract

We investigate the structural evolution of PtRu and CoRh ultra fine bimetallic particles as a function of their composition in the whole range of stoichiometry. Isolated particles embedded in an organic matrix are synthesized using chemical techniques in mild conditions. Their size, dispersion and structure are analyzed by HRTEM, WAXS and EXAFS techniques. The magnetic behavior of cobalt-based alloys is investigated by SQUID magnetometry. In the PtRu alloys, we demonstrate the role of composition in the structural transition from the face-centered cubic to the hexagonal close packed structure in nanoparticles and detail the mechanism of the transition. We point out the effect of size reduction and core-shell atomic distribution in the structure and the enhanced magnetization in CoRh bimetallic particles.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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