The frequency-dependent (ac) conductivity behaviour of ionically conducting glasses is discussed. A critique is given of the treatment of Almond and West for this behaviour. Two models are proposed instead to account for the observed ac loss data. One involves parallel relaxation processes and is a modification of a model originally developed for the case of large-polaron transport in amorphous semiconductors. The other is based on series relaxation, and is based on a model originally proposed by Glarum for the case of dielectric relaxation in molecular liquids. In the development given here, this model is modified so as to describe ionic transport, and a new microscopic transport mechanism is proposed-"diffusion-controlled relaxation"-which satisfies the requirements of the Glarum theory and which naturally incorporates cooperative ionic motions. For this reason, it is intuitively more appealing. © 1988.
