Bond valence analysis of transport pathways in RMC models of fast ion conducting glasses

Abstract

The bond valence method is applied to analyze local structure models from reverse Monte Carlo (RMC) fits to diffraction data. While our earlier studies demonstrated that for a wide range of silver ion conducting glasses both absolute value and activation energy of the ionic conductivity may be predicted from the volume fraction of regions with a sufficiently low valence mismatch for the silver ion, this investigation focuses on the precautions that have to be considered in a generalization of the bond valence approach to ionic conductors with various types of mobile ions and especially to alkali-metal ion conducting glasses. The separate structure conductivity correlations observed for each mobile cation can be combined to a unified empirical relationship by employing the square root of the cation mass as a scaling factor.