POLARONIC HOPPING CONDUCTION IN FE2O3-PBO-B2O3 GLASSES

DC electrical conductivity measurements have been carried out for xFe( 2)O(3). (100-x) [Pb0.3B(2)O(3)] glasses. Mott's model for the phonon a ssisted hopping of small polarons is effective to describe the high te mperature conductivities. The high temperature activation energy incre ases linearly with the Fe-Fe distance. At a constant temperature the p honon frequency is proportional to the site separation. The pre-expone ntial factor is predominant in changing the conductivity. The variable range hopping relations are valid also for the high temperature regio n. The conduction process is adiabatic in nature.