Interfacial conduction in ionically conducting two-phase materials: Calculations using the grain consolidation model

We have used the grain consolidation model to study the ionic conductivity in different two-phase composite systems where interfacial conductivity is assumed to be causing a conductivity enhancement. The model predicts results that are qualitatively similar to experimental data, displaying sharp 'knees' in the composition dependence. We have modeled materials consisting of grains in a host background where the grain size is either constant or varying with concentration. The model can explain even unusual behavior such as the existence of both a maximum and a minimum in conductivity at intermediate compositions. To achieve this we had to assume that the grains become smaller as their volume fraction increases.