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 usin g sigma(dc) were performed on compact pellets of these materials. The condu ctivity behavior in direct regime, sigma(dc) is described by the "small pol aron" model. The room temperature variation of log sigma(dc) with the activ ation energy of each composition, suggests an adiabatic hopping character t o the conduction. Application of Hunt's model to describe the ac conductivi ty 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.