Application of percolation theory in composites and glasses

Abstract

We discuss percolation models for ionic transport in dispersed ionic conductors and in glassy materials. In dispersed ionic conductors, the model takes into account that the ionic conductivity is strongly enhanced along the interface between (bad) ionic conductor and dispersed insulator. This leads to the occurrence of highly conducting percolating pathways at intermediate insulator concentration, by which the anomalous physical properties of the mixture can be satisfactorily described. In glassy ionic conductors, the model is based on the experimental evidence that ions maintain their distinct local environments. This leads to the formation of fluctuating percolation pathways. The connectivity of these pathways determines the ion mobility in the glassy network, and leads to an understanding of the well known transport anomalies in single and mixed alkali glasses.