@MISC{Macdonald84newaspects, author = {J. Ross Macdonald}, title = {NEW ASPECTS OF SOME SMALL-SIGNAL ac FREQUENCY RESPONSE FUNCTIONS}, year = {1984} }

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Abstract

First, it is shown how an expression for the ac conductivity of an ionically conducting material derived by Almond and West and co-workers from an earlier "universal dielectric response " equation of Jonscher may be related to and subsumed under a response function proposed much earlier. Doubt is cast on the identification ofa parameter in the Almond-West analysis as the ionic hopping frequency. The earlier function, first proposed by Ravaine and Souquet, is widely used to de-scribe the depressed arcs often obtained when experimental impedance data are plotted in the complex plane. A general relation which yields either this response or that of Cole and Cole for the complex dielectric onstant isdiscussed and shown to involve inadequate high and low frequency limits. Finally, a new distribution-of-activation-energies mod l which can fit both unsymmetric and symmetric arcs in either the impedance orcomplex dielectric onstant plane is briefly dis-cussed. This rr odel does yield physically realistic high and low frequency limiting response as well as predictions of the temperature d pendence of power-law frequency response xponents. Some time ago Almond, West and their co-workers showed in a series of papers [1-3] how one of Jonscher's empirical "universal dielectric response" equations [4] could be transformed into a form use-ful for analyzing the small-signal c response of ionic