On the origin of electrical relaxation in tellurite glasses

The dielectric properties of ternary silver vanadium tellurite and titanium vanadium tellurite glasses of the form [0.5[xAg2O-(1 − x)V2O5]–0.5TeO2, x = 0.1–0.8 mol] and [0.5[xTiO2-(1 − x)V2O5]–0.5TeO2, x = 0.1–0.6 mol] are investigated as a function of frequency (10 Hz–1 MHz) and temperature (70–425 K). Electrical relaxation is analyzed in terms of dielectric modulus and Kohlrausch–Williams–Watts (KWW) stretched exponential distribution function. The composition dependence of the stretched exponential parameter (β) is explained according to the variation of activation energy for dc conductivity and inter-charge separation in the two glass series. From the transition of polaronic to ionic conduction in silver vanadium tellurite glass series, it is established that ion–ion correlations are more effective in slowing down the electrical relaxation than the interactions between electronic charge carriers.