A new model for ac conduction in disordered solids

A new model based on a spatial electrical inhomogeneity of the material is presented to describe the ac conductivity of disordered solids. With the central assumption that both the dc and the ac conductivity are due to the same mechanism, the model calculation fits quantitatively the ac response against both temperature and frequency of some different amorphous solids. The analysis accentuates the difficulties and uncertainties which arise in deducing microscopic properties from ac conduction data. The model calculation suggests that at least in the high temperature regime processes working at the Fermi-level do not determine the ac behaviour of disordered solids.