Influence of doping level on electrical properties of ZnO-based composite varistor

ZnO-based varistors with. different doping levels of antimony and bismuth are prepared and their electrical properties are measured. It is found that when the doping level of Sb is small, with the amount of Sb2O3 increasing, the leakage cur-rent changes little, both nonlinear coefficient alpha(L) and breakdown nonlinear coefficient alpha(B) decrease but both field strength E-L and breakdown field strength E-B increase; when the doping level of Sb is high, with more Sb2O3 added, the leakage cur-rent increases sharply, alpha(L), and alpha(B) decrease further, and E-L and E-B drop down suddenly. With doping level of Bi increasing,the leakage current increases, alpha(L) and alpha(B) increase, but E-L and E-B decrease.