Effects of MnO2 doping in V2O5-doped ZnO varistor system

The effects of the amount of MnO2 (0.5–2 mol%) on the microstructure and the electrical properties have been studied in a binary ZnO–0.5 mol% V2O5 system. The microstructure of the samples consists mainly of ZnO grains with γ-Zn3(VO4)2 as the minority secondary phase. The cumulative addition of MnO2 improves the varistor performance by increasing the nonlinear coefficient α. The α-value is found to increase with the amount of MnO2, and a highest value of 31.8 is obtained for the sample doped with 2 mol% MnO2.