ELECTRICAL-CONDUCTION IN SOME SOL-GEL SILICATE-GLASSES

Measurements are reported for the electrical conductivity of different compositions of silicate glasses containing copper and vanadium in the temperature range 200-500 K. The experimental results for the two systems are found to be very similar and are analyzed with respect to theoretical models existing in the literature. At high temperatures, Mott's model of phonon-assisted small-polaron hopping between nearest neighbors is consistent with the data, while at low temperatures the variable-range-hopping model appears to be valid. The generalized polaron-hopping model of Schnakenberg and the percolation model applied to the small-polaron-hopping regime of Triberis and Friedman can also predict the temperature dependence of the conductivity data. The various model parameters obtained from the best fits are found to be consistent with the glass compositions.