Monte Carlo simulation of atoms diffusion via vacancies in fcc-structured nanofilms

Abstract

This research focuses on the Monte Carlo simulation of the correlation factor of atoms diffusing via vacancies in nanofilms with a face-centered cubic (fee) crystal lattice. The thickness of the films, defined as the number of crystal lattices along the axis perpendicular to the film surface, and the average number of jumps per atom (NJPA) are key variables in the simulation. Different jump frequency ratios of surface and interior atom-vacancy exchanges were also varied to investigate their influences on the correlation factor. The correlation factor of atoms approaches 0.781 when the film thickness is sufficiently large, which agrees well with the value for the 3D fee bulk lattice. As the film thickness is reduced to a minimum, the factor converges to 0.467, a value for the 2D square lattice. Abrupt change of the correlation factor occurs at a few numbers of lattices, i.e., in the nanofilm regime, which is mainly due to the confinement of atoms to nanofilms and could also be analyzed mathematically. (C) 2007 Elsevier Ltd. All rights reserved.