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Embedded atom calculations of the equilibrium shapes of 5–60 atom palladium nanocrystals

Published online by Cambridge University Press:  31 January 2011

A. Sachdev
Affiliation:
University of Illinois at Urbana–Champaign, 1209 West California Street, Urbana, Illinois 61801
R.I. Masel
Affiliation:
University of Illinois at Urbana–Champaign, 1209 West California Street, Urbana, Illinois 61801
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Abstract

The embedded atom method (EAM) has been used to compare the stability of a series of small palladium clusters with 5–60 atoms and a variety of shapes. It is found that the 13- and 55-atom icosahedra and cubo-octahedra are stable at 0 K. However, other sized icosahedra and cubo-octahedra are unstable at 0 K. Upon annealing, the icosahedra and cubo-octahedra reconstruct into nonpolyhedral structures which are highly strained. The strained structures are much more stable than the icosahedron or cubo-octahedron except when there are 13 or 55 atoms in the cluster. Further, there are many disordered shapes which are within 0.01 eV of the minimum energy structures at all cluster sizes including 13 and 55 atoms. We observe transitions between these low energy structures in Monte Carlo calculations. These results suggest that at equilibrium one should rarely observe polyhedral palladium particles. Instead, most of the particles should be disordered. Further, there should be a wide distribution of particle shapes in agreement with experiment.

Type
Articles
Copyright
Copyright © Materials Research Society 1993

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