Ionic Diffusion Phenomena in Superionic Conductors

Abstract

A molecular dynamics method has been applied in a study of silver diffusion in superionic conductor Ag2Te for several temperatures with use of effective interionic potentials. The static and dynamical structures are calculated. The density distribution of silver ions also has been obtained and it has suggested that a Ag ion, located at a tetrahedral site for most of the time, moves to a neighboring tetrahedral site via the vicinity of an octahedral site. The activation energy for an ionic diffusion also has been obtained from the Arrhenius plotting of the self-diffusion coefficient of Ag. To give an explanation of the Haven’s ratio obtained by a molecular dynamics calculation, a theory of caterpillar mechanism proposed by Yokota has been used. It has been considered that Ag ions occupy the tetrahedral sites and octahedral sites with different probability. It has been shown that the ratio of the frequency of a single jump to that of cooperative jumps increases with increasing temperature.