Transport mechanism in semiconducting glassy silicon vanadates

Measurements are reported for the electrical conductivity of the semiconducting glassy silicon vanadates in the temperature range 80-400 K. The experimental results have been analyzed with reference to the existing theoretical models of hopping conduction. The analysis shows that at high temperatures the conductivity data are consistent with Mott's model [J. Non-Cryst. Solids 1, 1 (1968)] of phonon-assisted polaronic hopping, while Mott's variable range hopping model [Philos. Mag. 19, 835 (1969)] is valid at low temperatures. The small polaron model of Schnakenberg [Phys. Status Solidi 28, 623 (1968)] is also found to be consistent with the temperature dependence of the conductivity. The temperature dependence of the conductivity can also be interpreted in the framework of the percolation model proposed by Triberis and Friedman [J. Phys. C 18, 2281 (1985)]. The analysis of the conductivity data also indicates that the hopping in these vanadate glasses occurs in the nonadiabatic regime.Peer Reviewe