The dc electrical conductivity of semiconducting TeO2-V2O5-MoO3 bulk glasses

The direct current electrical conductivity of ternary 40TeO(2)-(60- x) V2O5 - xMoO(3) glasses prepared by press-melt quenching technique was studied at temperatures between 90 and 403 K. From the conductivity - temperature relation, it was found that the small polaron hopping (SPH) model was applicable at the temperature above Theta(D)/2 (Theta(D): the Debye temperature), and the electrical conduction was due to the non-adiabatic SPH of electrons between vanadium ions for all glasses. The hopping carrier mobility and carrier density were determined at different temperatures. At temperatures lower than Theta(D)/2, a T-1/4 dependence of the conductivity was found, which can be described by the variable-range hopping (VRH) conduction mechanism. The density of states at ( or near) the Fermi level, N(E-F), was found from Mott parameters analysis, which was a function of V2O5 content. All the semiconducting glass compositions exhibited a crossover from VRH to SPH conduction at a characteristic temperature T-R >= Theta(D/2).