The prediction of correlation factors and motion energies for diffusion of transition metal ions in CoO and NiO

Abstract

We use atomistic modelling methods to predict correlation factors and motion energies for the diffusion of impurity ions in CoO and NiO. These use the shell model, and include the effects of impurity-vacancy binding, the temperature dependence of the extent of non-stoichiometry, and the explicit calculation of the ratios of critical jump frequencies. We further test the validity of some approximations to jump frequencies. Despite the success of the correlation factor calculations, the absolute motion energies do not agree well with experiment. We have identified the reason for this, associated with the open-shell transition metal ions; quantitative estimates are given in a subsequent paper.