Studies of conductivity in mixed alkali vanadotellurite glasses

Abstract

A set of novel mixed alkali vanadotellurite glasses (V2O 5)O0.25(Li2O)0.25(K 2O)x(TeO2)1-x (0.05 > x < 0.30) have been investigated for density and dc conductivity in the temperature range from 380 K to 480 K. The density exhibited a minimum, and molar volume showed a maximum at x = 0.20. Conductivity data have been analyzed in the light of Mott's small polaron hopping model and high temperature activation energy values have been determined. The conductivity and activation energy also passed through a minimum and maximum, respectively, at x = 0.20. This result has been attributed to the mixed alkali effect. The strength of mixed alkali effect has been estimated. It is for the first time that vanadotellurite glasses are shown to exhibit mixed alkali effect. Various physical and polaron hopping parameters have been determined and discussed.