Hopping conduction and superionic conductors

Abstract

The frequency dependence of the conductivity of superionic conductors is investigated from a classical-hopping-model point of view. It is shown both formally and through an example that any hopping model must yield a conductivity which increases monotonically with frequency up to frequencies comparable with phonon frequencies. This result is generally consistent with experimental data on $\beta$-alumina, but is inconsistent with data on AgI.