AC conductivity studies in rare earth ions doped vanadotellurite glasses

Abstract

The frequency and temperature dependence of ac electrical conductivity in the temperature range 300-525 K and frequency range 50 Hz to 5 MHz has been investigated in La2O and CeO2 doped vanadotellurite glasses. The electrical conduction has been observed to be due to small polaron hopping at high temperatures. Frequency dependence of ac conductivity has been explained using correlated barrier hopping (CBH) model. The conductivity, at all studied frequencies and temperatures, decreased and activation energy increased with increase in rare earth ion concentration in both La2O and CeO2 doped vanadotellurite glasses, which has been attributed to the hindrance to the electronic motion offered by rare earth ions. The dielectric constant and dielectric loss increased with increase in temperature and decreased with increase in frequency and rare earth ions content. It is for the first time that the La2O and CeO2 doped vanadotellurite glasses have been investigated for ac conductivity and dielectric properties over a wide range of frequency and temperature. © 2007 Elsevier B.V. All rights reserved.