Electrical Conductivity of V2O5-TeO2-Sb Glasses at Low Temperatures

Semiconducting glasses of the type 40TeO(2)-(60 - x) V2O5-xSb were prepared by rapid melt quenching and their dc electrical conductivity was measured in the temperature range 180-296 K. For these glassy samples, the dc electrical conductivity ranged from 2.26 x 10(-7) S cm(-1) to 1.11 x 10(-5) S cm(-1) at 296 K, indicating the conductivity is enhanced by increasing the V2O5 content. These experimental results could be explained on the basis of different mechanisms (based on polaron-hopping theory) in the different temperature regions. At temperatures above I similar to (D)/2 (where I similar to (D) is the Debye temperature), the non-adiabatic small polaron hopping (NASPH) model is consistent with the data, whereas at temperatures below I similar to (D)/2, a T (-1/4) dependence of the conductivity indicative of the variable range hopping (VRH) mechanism is dominant. For all these glasses crossover from SPH to VRH conduction was observed at a characteristic temperature T (R) a parts per thousand currency sign I similar to (D)/2. In this study, the hopping carrier density and carrier mobility were determined at different temperatures. N (E (F)), the density of states at (or near) the Fermi level, was also determined from the Mott variables; the results were dependent on V2O5 content.