Complex-impedance response of an Ag/TeO2–V2O5/Ag structure

The ac conductivity of glass samples of composition 50 mol% TeO2 and 50 mol% V2O5 has been analyzed. The samples were prepared by the usual melt-quench method. The electrical conductance and capacitance were measured over a frequency range of 20 Hz to 1 MHz and a temperature range of 293–450 K; these reveal semiconducting features based predominantly on an ionic mechanism. This is reflected in a low-frequency Cole–Cole dependence z″ (z′) for the impedance and in a linear dependence ɛ″(ɛ′) for the dielectric constant throughout the temperature range. The dielectric and complex-impedance response of the structure measured is discussed. The relaxation time τ0 was found to decrease with increasing temperature. An equivalent circuit was proposed and its parameters calculated. Good agreement between a double-layer physical model and the parameters of the equivalent electrical circuit was obtained.