DC conductivity in some alkali doped vanadotellurite glasses

Abstract

Lithium-vanadium-tellurite glasses in the composition (V2O5)0.4-(Li2O)x-(TeO2)0.6 - x; 0.10 ? x ? 0.50, are investigated for room temperature density and dc electrical conductivity in the temperature range 300 K to 525 K. The density increased with increasing Li2O up to 40-mol% and then decreased for further doping of Li2O. Mixed electronic-ionic conduction has been observed in the present set of glasses. The change over of conduction mechanism from predominantly electronic to ionic is observed to be occurring at x = 0.4. The high temperature (T > ?D / 2) conductivity data obeyed Mott's small polaron hopping model (SPH) and the low temperature (T < ?D / 2) conductivity has been analyzed in the light of Motts variable range hopping (VRH) and Greaves VRH conduction models. Various physical parameters associated with theoretical models are estimated. It is for the first time that lithium doped vanadotellurite glasses in the composition mentioned in this paper have been investigated for density and dc conductivity and, the conductivity data for temperatures above and below (?D / 2) have been thoroughly analyzed in terms of theoretical models. © 2007 Elsevier B.V. All rights reserved.