dc and ac Conductivities of (V2O5)x(B2O3)1-x oxide glasses

Glasses of composition (V2O5)(x)(B2O3)(1-x) With x = 0.1, 0.3, 0.5, 0.7 and 0.9 were obtained by a quenching technique. Conductivity measurements using sigma(dc) were performed on compact pellets of these materials. The conductivity behavior in direct regime, sigma(dc) is described by the "small polaron" model. The room temperature variation of log sigma(dc) with the activation energy of each composition, suggests an adiabatic hopping character to the conduction. Application of Hunt's model to describe the ac conductivity behavior shows that the relaxation process has a local character and can be described by hops between each pair of sites. (C) 2000 Elsevier Science Ltd. All rights reserved.