Electrical conduction and switching properties of As2O3·V2O5·FeO glasses

Abstract

Electrical conductivity, negative resistance and joule heating characteristics for x%As2O3·(80-x)%V2O5·20%FeO bulk glasses with (25 ≤ x ≤ 45), have been investigated at various temperatures, frequencies and thicknesses. Electrical conductivity is found to increase from 3 × 10−5 to 0.012 Ω−1 m−1 depending on the composition. The experimental results for electrical conductivity has been analyzed using varies models. The dc activation energy (Edc) is estimated to be in the range 0.25–0.5 eV depending on the value of x. According to the multi phonon hopping model, the dc conductivity is found to be relative to Tp with the exponent p between 8.2 and 10.5. The fitted data of the ac conductivity according to Dyre’s percolation path approximation and Almond–West power law equation showed an excellent collapse to a single master curve. This indicates that there is a good time–temperature superposition in these glasses. Threshold switching type is detected in all the samples with maximum current of about 3 mA. The threshold voltage Vth values are affected by ambient temperature, sample thickness and sample composition ratios. The activation energy for switching is found to decrease with increasing the percentage of As2O3. Variations of the surface temperature during the switching cycles suggest the applicability of the electrothermal mechanism.