1. College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
2. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China
3. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Science, Beijing 100049, China
4. Wuhan National Laboratory for Optoelectronics (WNLO) and School of Optical and Electronic Information, Huazhong University of Science and Technology (HUST), Wuhan 430074, P. R. China