One-dimensional models for superionic conductors

Abstract

Three one-dimensional models, interstitialcylike, vacancylike, and interstitiallike, are constructed to study properties of superionic conductors. Potential energy curves along the diffusion path due to all ions other than the conducting species are simulated by (V0/2) [1−cos(2πx/a)], where a is the lattice constant. By considering only the Coulombic and repulsive potentials among conducting ions, the activation energy Ea is calculated as a function of V0. It is shown that due to local correlative motions of conducting ions, the values of Ea are much smaller than V0. The correspondences between the models and actual superionic conductors such as β-alumina, β″-alumina, and α-AgI are discussed.