Abstract
Under the premise of using the solid-phase method to pre-sinter Bi(2)O(3) and Sb(2)O(3) into BiSbO(4) as a substitute for equal amounts of Bi(2)O(3) and Sb(2)O(3) in the formula, the effects of co-doping with In(NO(3))(3), Al(NO(3))(3), and Y(NO(3))(3) on the microstructure and electrical properties of ZnO varistors were studied. The experimental results show that with an increase in In(3+)-doped molar concentration, the leakage current of the ZnO varistor shows a rapid decrease and then a slow increase trend. However, the nonlinear coefficient is the opposite of it. With the combined effect of the rare earth element Y(3+), the average grain size is significantly reduced, which leads to an increase in the voltage gradient. At the same time, a certain amount of doped In(3+) and Al(3+) is dissolved into the grains, resulting in a decrease in grain resistance and thus a low level of residual voltage. The varistor with 0.6 mol% In(3+), 0.1 mol% Al(3+), and 0.9 mol% Y(3+) doping ratios exhibits excellent overall performance. The nonlinear coefficient is 62.2, with the leakage current being 1.46 µA/cm(2) and the voltage gradient being 558 V/mm, and the residual voltage ratio is 1.73. The prepared co-doped ZnO varistors will provide better protection for metal oxide surge arresters.