Li 2 O-PbO-P 2 O 5 glasses mixed with different concentrations of SnO 2 (ranging from 0 to 7.0 mol%) were prepared. AC conductivity (σ ac ) and dielectric dispersion have been studied. The results were analyzed on the basis of space charge and orientation polarization models. σ ac exhibited the maximal effect, whereas the activation energy for the conductivity demonstrated minimum at 3.0 mol% of SnO 2 . In the low-temperature region, σ ac is nearly temperatureindependent and is varied linearly with frequency. Such behavior is explained based on quantum mechanical tunneling (QMT) model. These results additionally confirm that there is both ionic and electronic originated conductivity in these glasses. The quantitative analysis of these results with the aid of data on optical absorption and IR spectral studies indicated that the network of the glass mixed with 3.0 mol% of SnO 2 possessed higher degree of disorder and exhibited maximum conductivity.

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