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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.42  No.8 (2001)  >  pp.1474-1479

MATERIALS TRANSACTIONS
<<Previous article Vol.42  No.8 (2001)   pp.1474 - 1479 Next article>>

Size Effect on the Atomistic Structure of Metallic Atom Clusters

Hiroshi Fujita1) and Naoya Fujita2)
1) Emeritus Professor, Osaka University
2) Osaka Prefectural Industrial Technology Research Institute


The atomistic structure of metallic atom clusters is discussed based on the experimental results with the following conclusions: (1) When ultrafine particles of metals become smaller than the critical sizes corresponding to the nucleus size of the crystals, they behave as atom clusters and their atomistic structure changes as a function of the number of constituent atoms, i.e., the many-body potential. (2) Icosahedrons are formed first and change to the cuboctahedral structure before such atom clusters take the final crystal structures. (3) The phonon mode of these atomistic structures is very much softened, and thus the zigzag atom-chains are formed dynamically around the average position of atoms even in the cuboctahedral structure. (4) The hybrid orbital corresponding to the final crystal structure is formed when atom clusters grow to the critical size. As a result, the binding strength sufficiently increases along a certain crystal axis such as the ⟨110⟩ in the fcc structure and the ⟨111⟩ in the bcc one, so that atomic rearrangement can occur within the ultrafine particles, including disappearance of multi-twin in Au particles, to take the bonding state of crystals.


Keyword:
dynamic zigzag atom-chain, icosahedral structure unit, cuboctahedron, intermediate atomistic structures, hybrid orbital, many-body potential

Received: February 08, 2001
Accepted: April 09, 2001 , Published online: September 06, 2005
Copyright (c) 2005 The Japan Institute of Metals

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