ZHU Zhixiang 1, ZHANG Qiang 1, CAO Wei 2，LIU Jing 3, GU Shanqiang 2, WAN Shuai 2, SUN Yuyang 4, WU Yanqi 4, 5, PAN Junqiao 4, 5
(1. State Key Laboratory of Advanced Power Transmission Technology, Global Energy Interconnection Research Institute Co., Ltd., Beijing 102211, China; 2. Hubei Key Laboratory of Power Grid Lightning Risk Prevention, Wuhan NARI Limited Company Grid Electric Power Research Institute, Wuhan 430074, Hubei, China; 3. State Grid Anhui Electric Power Co., Ltd. Hefei 230022, Anhui, China; 4. Tongxiang Tsingfeng Technology Co., Ltd. Jiaxing 314501, Zhejiang, China; 5. Foshan (Southern China) Institute For New Materials, Foshan 528200, Guangdong, China)
Abstract: ZnO varistors modified with various rare earth oxides, including La2O3, CeO2, Sm2O3 and Y2O3, were prepared with nanosized ZnO powder by using the conventional ceramic process. The effect of rare earth oxide dopants on the performance of ZnO varistors was systematically studied. The samples were characterized by using XRD, SEM, and DC parameter. It was found that rare earth oxides inhibited the grain growth of ZnO, improved voltage gradient and nonlinear coefficient and reduced the leakage current of the samples. The sample with 0.7 mol% of Y2O3 displayed the optimized performance, with a voltage gradient of 613 V/mm, a leakage current (IL) of 0.26 μA and a nonlinear coefficient (α) of 60.4.
Key words: ZnO varistor; rare earth oxide; microstructure; electrical properties