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Volume 138, 2008
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Structure and chemical ordering in CoPt nanoalloys

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Abstract

The structure and chemical ordering of CoPt nanoclusters in the size range of 1 to 3 nm are investigated by global optimization methods and Monte Carlo simulations using a many body potential derived from the tight binding model. For the smaller systems (number of atoms N < 100), the optimized clusters display a polyicosahedral-like atomic structure with a little core-shell chemical ordering characterized by a particular surface chemical configuration: some pentagonal or hexagonal Pt rings centered, respectively on a Co atom or a Co dimer. A transition to the decahedral symmetry occurs at about N = 100 atoms, with a pseudo L10 ordered phase in each tetrahedral unit. For larger cluster sizes, 201 < N < 1289, the L10-ordered/disordered transition on the face centered cubic truncated octahedron is studied by canonical Monte Carlo simulations showing that the critical disordering temperature decreases with the cluster size. We also notice a Co surface segregation especially at edges and, possibly, (100) facets, depending on the cluster size, on both cubic and fivefold symmetry structures.

  • This article is part of the themed collection: Nanoalloys
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Publication details

The article was received on 10 Apr 2007, accepted on 11 May 2007 and first published on 28 Sep 2007


Article type: Paper
DOI: 10.1039/B705415G
Citation: Faraday Discuss., 2008,138, 193-210
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    Structure and chemical ordering in CoPt nanoalloys

    G. Rossi, R. Ferrando and C. Mottet, Faraday Discuss., 2008, 138, 193
    DOI: 10.1039/B705415G

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