1. School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), Tianjin University, Tianjin300350, P. R. China
2. Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University, Binhai New City, Fuzhou350207, P. R. China
3. Institute of Physics, Chinese Academy of Sciences, Beijing10089, P. R. China
4. State Key Laboratory of Marine Resource Utilization in South China Sea, School of Materials Science and Engineering, Hainan University, Haikou570228, P. R. China