Effect of Sc2O3 doping on microstructure and electrical properties of ZnO–Bi2O3-based varistors

ZnO varistors are widely used in electrical systems. In this study, the effects of different contents of Sc2O3 doping on the microstructure and electrical properties of ZnO varistors were systematically analyzed. The results show that the doping of Sc2O3 is conducive to the uniform growth of the ZnO grains and improves the breakdown field strength of varistors. At the same time, Sc2O3 doping improves the barrier height of the varistors, resulting in a significant increase in nonlinear coefficient and a decrease in leakage current density. The sample doped with 0.15 mol% Sc2O3 exhibited excellent electrical properties with breakdown field strength of 696.13 V/mm, a leakage current density of 1.26 μA cm−2, and a nonlinear coefficient of 55.00. The Sc2O3 doped samples have good performance, which is of guiding significance for the study of other trivalent and tetravalent ion doping with a radius similar to that of Zn2+.