Regulation of the electrical properties of ZnO varistors by Co2O3 doping

To address the issue of high leakage current caused by ZnO-Ga₂O₃-based varistors, this study introduces different concentrations of Co₂O₃ as auxiliary dopants. ZnO-based ceramic samples with varying Co₂O₃ doping levels were prepared via the solid-state reaction method, their effects on the microstructure and electrical properties of ZnO varistors were systematically analyzed. The study explored the role of Co₂O₃ doping in regulating the microstructure and electrical performance of ZnO varistors. The results demonstrate that Co₂O₃ doping enhances the nonlinear coefficient, suppresses leakage current, and increases the barrier height at grain boundaries. When the doping concentration of Co₂O₃ reaches 0.75 mol%, the nonlinear coefficient of ZnO varistors increases from 26 to 54, while the leakage current decreases from 370 μA/cm² to 0.32 μA/cm², exhibiting superior performance.