The conductivity of a random-resistor model, recently proposed for dispersed ionic conductors, is calculated using the effective-medium approximation. The results are compared with Monte Carlo simulations (MCS) for two- and three-dimensional systems. This simple analytical approach describes satisfactorily both the temperature and composition dependence of the conductivity in three dimensions and predicts a behavior of the activation energy for a composite in agreement with MCS and experiments.

• Received 21 September 1987

DOI:https://doi.org/10.1103/PhysRevB.37.3696