Electrical conduction and dielectric studies of ZnO pellets

A series of Zinc Oxide pellets sintered at different temperatures was studied by means of dielectric spectroscopy in the wide frequency range of 1–106 Hz and temperature interval from −100 °C to 30 °C. Electrical conductivity was analysed using Jonsher's universal power law, and the values of s were found to decrease with the increase in temperature, which agrees well with the correlation barrier hopping (CBH) model.As the temperature increased, energy activation Edc became less than 0.39 eV and dc conductivity (σdc) values in the range of 1.9×10−14–9.7×10−10 Ω m−1 were observed. The dielectric modulus showed ionic polarisation at the intermediate and high frequencies related to oxygen interstitial Oi, oxygen vacancy VO and Zinc interstitial Zni. At low frequency, it revealed a Maxwell–Wagner–Sillars relaxation with barrier heights of grain boundaries between 0.74 and 0.88 eV for all the studied pellets.