AC CONDUCTIVITY IN DISPERSED IONIC CONDUCTORS - THE EFFECTIVE-MEDIUM APPROXIMATION

We developed a stochastic transport theory for the calculation of the ac-conductivity in two-phase mixture materials (with high interface co nductance). A perturbation around the different configurational interf ace paths is introduced by using the Effective Medium Approximation (E MA), Data of LiI conductivity after the addition of an insulating seco nd phase Al2O3 show that our approach describes the main features of t he ac-conductivity. The dielectric constant and the static effective c apacitance, as a function of the concentration of the insulating mater ial, are compared against previous Monte Carlo simulations and Renorma lization Group results. Conductivity (Cole-Cole plots) and dielectric properties of dispersed ionic conductors are studied in a self-consist ency way, A random walk in a random-resistor network and the use of an effective electric circuit are presented in order to describe all the features of the ac-response in these materials.