Effects of In2O3 doping on microstructure and electrical properties of ZnO low-voltage varistor

In this work, high-performance ZnO–Bi2O3 based low-voltage varistors were prepared by doping In2O3. When the breakdown voltage was low, the varistor obtained a relatively high nonlinear coefficient. Through systematic research on the microstructure and electrical properties of the ZnO varistor doped with In2O3, it was found that when In2O3 was co-doped with TiO2, it was beneficial to improve the grain boundary barrier of the low-voltage varistor, resulting in an increase in the nonlinear coefficient and a decrease in the leakage current. Among them, when the doping amount of In2O3 was 0.012 mol%, the electrical performance was the best, the threshold voltage was 191 V/mm, the nonlinear coefficient was 37.1, and the leakage current was 0.42 μA. At the same time, the doping of In2O3 increased the grain boundary resistance, which was beneficial to improve the electrical stability of the samples.