Microstructure and electrical properties of Sc2O3-doped ZnO–Bi2O3-based varistor ceramics

The microstructure and electrical properties of ZnO–Bi2O3-based varistor ceramics doped with different Sc2O3 content sintered at 1100 °C were investigated. The results showed that the nonlinear coefficient of the varistor ceramics with Sc2O3 were in the range of 18–54, the threshold voltage in the range of 250–332 V/mm, the leakage current in the range of 0.1–23.0 μA, with addition of 0–1.00 mol% Sc2O3. The ZnO–Bi2O3-based varistor ceramics doped with Sc2O3 content of 0.12 mol% exhibited the highest nonlinearity, in which the nonlinear coefficient is 54, the threshold voltage and the leakage current is 278 V/mm and 2.9 μA, respectively. The results confirmed that doping with Sc2O3 was a very promising route for the production of the higher nonlinear coefficient of ZnO–Bi2O3-based varistor ceramics, and determining the proper amounts of addition of Sc2O3 was of great importance.