An evaluation of random R-C networks for modelling the bulk ac electrical response of ionic conductors

The ac electrical characteristics of a 2-D square randomly filled RC networ k are shown to exhibit many features in common with those of a typical ioni c conductor. These include the 'universal' power law frequency responses of ac conductivity and permittivity, It is suggested that a random network of ion conduction channels and insulating islands may provide a realistic mod el of the conduction paths within a bulk ionic conductor. DC ionic conducti vity is identified with a resistive percolation path through the network an d the higher frequency power law component with that of the random network of ac conducting linked capacitive and conductive regions. The dielectric l oss peak associated with ionic conductors is also found to be a random R-C network characteristic. The effect of the insulating islands having a Debye -like capacitance is modelled and ZrO2 12 mol% Y2O3 data are presented whic h exhibit the effects predicted. (C) 1999 Elsevier Science B.V. All rights reserved.