Effect of V2O5 on electrical and microstructural properties of ZnOceramics

ZnO ceramics with small amounts of V2O5 as a varistor-former ranging from 1-5 mol% were prepared by conventional powder processing route and sintered at 700, 800 and 900 °C for 2 h. It was observed that the grain growth behavior in ZnO ceramics was strongly influenced by doping with V2O5. Morever, lower temperatures about 900 °C could be used for sintering. The microstructure of the samples consists of ZnO grains as a main phase and Zn3(VO4)2 as a secondary phase. All of the prepared ceramics showed characteristic of non-ohmic current-voltage behavior. Non-linear coefficient increased with increase in V2O5 content and sintering temperature. Activation energy of the ceramics lies in the range of 0.071-0.402 eV which decreased with increase in V2O5 content and sintering temperature. The origin of the non-linear electrical behavior was explained by considering the solid state reactions and formation of the potential barriers at grain boundaries.