LOCAL FIELD EFFECTS IN IONIC CONDUCTORS

An analysis is carried out of the effects produced by the possibly strong electric dipolar coupling between intracell dielectric response and intercell hopping response in a simple model of thermally activated ionic conductivity. The results suggest the presence of two marked effects. The first is an enhancement of the low-frequency ionic conductivity over the noninteracting equivalent caused by the increase in effective local perturbing field (over the applied field) which is produced by the local vibrational dipoles. The second is the development of an inductive contribution to the real part of the dielectric constant which increases exponentially with increasing temperature and which can easily dominate this reponse component at moderate carrier concentrations. A diverging conductivity is predicted on approach to a second-order dielectric instability. © 1979 The American Physical Society.