Distributions of activation energies in ionic glasses

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Abstract
Model calculations are used to show that a single, well-defined activation energy may be observed governing both d.c. conduction and a.c. dielectric loss even if there is a wide spread of activation energies at individual ion sites. A series-parallel combination formula and a circuit mesh formula have been used with normal distributions of activation energies. Both formulae give similar results. The mesh formula is considered to be based on a more realistic representation of the ion sites but is more difficult to use with large numbers of sites. Neither formula gives dielectric modulus loss curves that are as independent of temperature as those observed experimentally for ionic glasses.