1 Center of Advanced Ceramic Materials and Devices, Yangtze Delta Region Institute of Tsinghua University, Zhejiang 314006, P. R. China
2 State Grid Henan Electric Power Research Institute, Zhengzhou 450052, P. R. China
3 State Grid Jinhua Power Supply Company, Jinhua 321001, P. R. China
4 State Grid East Inner Mongolia Electric Power Research Institute, Hohhot 010020, P. R. China
5 State Key Laboratory of Advanced Power Transmission Technology, Global Energy Interconnection Research Institute Co. Ltd., Changping District, Beijing 102209, P. R. China
6 Foshan (Southern China) Institute for New Materials, Foshan 528200, P. R. China
7 Research Center for Advanced Functional Ceramics, Wuzhen Laboratory, Jiaxing 314500, P. R. China