Atom ordering in cuboctahedral Ni-Al nanoalloys |
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Authors: | Nicholas T Wilson Roy L Johnston |
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Institution: | School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK |
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Abstract: | Energy calculations have been carried out on high-symmetry cuboctahedral Ni-Al nanoalloy clusters, of varying composition, with the interatomic interactions modelled by the Gupta many-body potential. Relaxations of cuboctahedral fragments cut from the bulk lattice of Ni3Al, with 13-561 atoms, were undertaken, as were relaxations of high symmetry clusters with 55 and 147 atoms. The lowest energy isomers were found to be dominated by three factors: the tendency toward mixing due to the favourable energy of mixing, ΔmixE; the size difference between nickel and aluminium; and the higher cohesive and surface energy of nickel compared to aluminium. The latter two factors favour Al-segregation to the surface. The most stable Ni:Al composition approaches 3:1 for larger clusters. |
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Keywords: | Atom ordering Clusters Geometric shells Gupta potential Nanoalloys Nanoparticles Nickel-aluminium alloys Segregation Simulation |
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