A wide site-to-site distribution of activation energies was assumed to be involved in ion migration. The resultant electrical properties were calculated by using a circuit network with a distribution of resistances. A hyperbolic sine-law dependence of the current upon the field was applied to the resistors of the network. At limiting points (bottlenecks) in the network, the local effective field was greater than that which was applied to the network as a whole. This resulted in departures from Ohm’s law under anomalously low applied fields. Almost linear Poole-Frenkel plots of log[current] versus field were obtained; in approximate agreement with experimental results. A marked reduction in dielectric dispersion occurred at high fields.

J.O.Isard: Journal of Non-Crystalline Solids, 1996, 202[1-2], 137-44