1. State Key Laboratory of High Performance, Ceramics and Superfine Microstructure; Shanghai Institute of Ceramics, Chinese Academy of Sciences; 1295 Dingxi Road Shanghai 200050 China
2. University of Chinese Academy of Sciences; Beijing 100049 China
3. CAS Key Laboratory of Energy Conversion Materials; Shanghai Institute of Ceramics, Chinese Academy of Sciences; 1295 Dingxi Road Shanghai 200050 China
4. Hefei National Laboratory for Physical Sciences at the Microscale; University of Science and Technology of China; Hefei Anhui 230026 China
5. Shanghai Synchrotron Radiation Facility; Shanghai Institute of Applied Physics, Chinese Academy of Sciences; 239 Zhangheng Road Shanghai 201204 China
6. Department of Physics; University of Michigan; Ann Arbor Michigan 48109 USA