Energy basis of dielectric relaxation loss

Abstract

JONSCHER has reviewed the phenomenology of dielectric, mechanical and some magnetic relaxations in a very wide range of materials1. He found2 that a fundamental insight into the physics of such processes may be obtained by considering that the ratio of the energy dissipated to the energy stored in these materials per radian of sinusoidal excitation is a constant which does not change over a very wide range of frequency. This observation, the so-called ‘universal dielectric response’, has been derived by examining the behaviour of dielectric loss in the frequency and time domains, and tentatively modelled in terms of a partial screening mechanism2–4. Here we shall discuss Jonscher's work within the context of earlier work, and it will be shown that the presence of a loss peak in the frequency domain, or a change in the slope of the double logarithmic time–domain graph, need not require the two consecutive processes in the material that have been thought to be necessary1,4. Subsequently, the clarified ‘universal dielectric response’ is used to interpret various empirical loci on the complex permittivity plane, Cole–Cole5, Davidson–Cole6 and Williams–Watts7–9 plots, and to compare these loci with the simple Debye form in terms of the behaviour of a single ‘storage parameter’, s, replacing Jonscher's n and m and the previously physically uninterpreted α of Cole and Cole and β of Davidson and Cole.