A general theoretical approach to the mixed-alkali effect in glasses was based upon the idea that the covalent host network created various structural energy landscapes for different types of mobile ion. By deriving a simplified model from this approach, it was shown how experimentally observed changes in ion mobility, during the mixing of 2 types of ion or during changes in the total concentration of mobile ions, could be explained. Computer simulations, based upon the model, suggested that Coulomb forces had to be taken into account in order to explain the differing behaviours of activation energies in single modified and mixed-ion glasses. It was also shown how the mixed-alkali internal friction peak resulted from the diffusional exchange processes of unlike ions in the glassy network.

Towards a Theory for the Mixed Alkali Effect in Glasses. P.Maass: Journal of Non-Crystalline Solids, 1999, 255[1], 35-46