1. State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of Ceramics Chinese Academy of Sciences 1295 Ding‐xi Road Shanghai 200050 P. R. China
2. University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Chemical Science and Engineering Division Argonne National Laboratory 9700 Cass Avenue Lemont IL 60439 USA
4. X‐ray Science Division, Advanced Photon Source Argonne National Laboratory 9700 Cass Avenue Lemont IL 60439 USA