Nanoalloys pp 227-257 | Cite as

Segregation and Phase Transitions in Reduced Dimension: From Bulk to Clusters via Surfaces

  • Jérôme Creuze
  • Fabienne Berthier
  • Bernard Legrand
Chapter
Part of the Engineering Materials book series (ENG.MAT.)

Abstract

To describe the thermodynamics of bimetallic clusters, we use approaches that have been successfully employed for bulk alloys and their surfaces. We detail what happens for bulk and surface phase transitions when considering nanoalloys with a tendency to phase separation. A rigid-lattice approach allows us to analyze the behaviour of surface and core shells of the nanoalloys. We discuss the existence of bistabilities (or dynamical equilibrium) which are the analogous of surface and bulk phase transitions in semi-infinite alloys. Such dynamical equilibrium is susceptible to affect the cluster facets in an individual way (individual dynamical equilibrium), whereas the inner shells show a collective bistability (collective dynamical equilibrium). Then, we compare these bistabilities obtained in the semi-grand canonical ensemble with the results obtained in the canonical ensemble, before discussing the relation between experimental conditions and the two thermodynamic ensembles. Finally, a first attempt to establish generalized phase diagram for bimetallic clusters is proposed.

Keywords

Enthalpy Catalysis 

Notes

Acknowledgments

It is a pleasure to acknowledge the many collaborators and colleagues who have significantly contributed to this work: Virginie Moreno, Florence Lequien, Laure Delfour, Mariem Lamloum and Mohamed Briki. We are indebted to Isabelle Braems, Christine Mottet, Guy Tréglia, François Ducastelle, Christian Ricolleau and Cyril Langlois for many stimulating and useful discussions throughout the course of this research.

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Copyright information

© Springer-Verlag London 2012

Authors and Affiliations

  • Jérôme Creuze
    • 1
  • Fabienne Berthier
    • 1
    • 2
  • Bernard Legrand
    • 3
  1. 1.ICMMO/LEMHEUniv. Paris-SudOrsayFrance
  2. 2.CNRSOrsayFrance
  3. 3.SRMP-DMNCEA SaclayGif sur Yvette CedexFrance

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