A SURVEY OF EXISTING THEORIES AND A NEW PROPOSAL REGARDING IONIC-CONDUCTIVITY IN MIXED-ALKALI SILICATE-GLASSES

A previously reported phenomenological model, derived from the thermodynamics of irreversible processes of conductivity, has been shown to be able to account for many different mixed-alkali ionic conductivities in silicate and germanate glasses, over a wide range of temperatures. The interaction energy between two different alkali ions is consistent with the microscopic theory introduced by Hendrickson and Bray. A comparison of the present model with the old ones has been performed in order to point out both the possible common features as well as the progress made towards a unified theory of the conductivity in glasses.