From bond valence maps to energy landscapes for mobile ions in ion-conducting solids

Applications of the bond valence method for the analysis of ion transport pathways in crystalline cation ion conductors with various mobile cations are reviewed and an extension of the approach to anion conductors is discussed. In both cases the discussion highlights structures, where special care is required in the interpretation of the pathway model. The extension of the bond valence approach enhances the application range of the method for the identification of the ion transport mechanisms to materials, where both cations and anions have to be considered as potentially mobile species, as demonstrated for the presumed trivalent cation conductor Sc2(WO4)3.