The frequency dispersions of 2 oxide glasses having widely differing ion concentrations were studied. The results showed that ion–ion interactions and correlations played an important role in determining the direct-current conductivity and the low-frequency cooperative part of the dispersion. The cause of a near-constant loss, which always appeared at higher frequencies and lower temperatures, was traced to the occurrence of few and infrequent independent jumps of ions out of their cages; without any effect of ion–ion correlation. The coupling model quantitatively supported this interpretation of the dispersion. The greatest influence of the mixed alkali effect in glasses occurred in the dilute foreign alkali region; where one foreign alkali immobilized a large number of host ions. This feature of the mixed alkali effect could be explained only if ion–ion interaction and correlation were included in the description of the ion dynamics.

The Dynamics of Ions in Glasses - Importance of Ion–Ion Interactions. K.L.Ngai: Journal of Non-Crystalline Solids, 2003, 323[1-3], 120-6