RELAXATION PROCESSES IN IONICALLY CONDUCTING GLASSES

The universal aspects of ionic conductivity in glass include the conductivity spectrum, which extends from 'dc' to the far infrared region, and the rather broad electric modulus spectra which highlight the 'distribution of conductivity relaxation times' (or, alternatively, the non-exponential decay of the electric field). This universality is also manifested in the existence of numerically different (microscopic and macroscopic) relaxation times which complicate the interpretation of data from NMR, QENS, and other kinds of relaxation spectroscopy. It is suggested that this universality is consistent with topological constraints imposed by the cluster-tissue structure of glass. The question is posed as to what extent the properties of silver iodomolybdate glasses (which are structurally well characterised) are paradigmatic of conducting glasses generally. In any event, the discussion of electrical properties can no longer be separated from a discussion of glass structure.