Vibrational properties of a Sigma 5(310) 001 NiO grain boundary as a function of temperature: A molecular dynamics simulation

Abstract

In this communication we present results concerning the study of the vibrational properties of a Sigma5(310)[001] NiO grain boundary by molecular dynamics simulations. The phonon density of states of the cation and anion sublattice in the boundary region is calculated as a function of temperature in the directions normal and parallel to the boundary plane. The obtained results are compared with those obtained for the bulk and the differences are discussed. We have also calculated the mean square displacements of the cations and anions in the grain boundary region as a function of temperature in the direction normal and parallel to the boundary plane and the results are compared with those of the bulk. The combination of the above results leads to the conclusion that the ions are more loosely coupled in the direction normal to the boundary plane than parallel to it and this anisotropy is persistent up to high temperatures. The increase of temperature also leads to the softening of the binding of the ions in both directions. (C) 2002 Elsevier Science B.V. All rights reserved.