1. Key Laboratory of Science and Technology on Wear and Protection of Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou 730000, China
2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3. National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, China Academy of Space Technology, Lanzhou 730000, China