1. Center for High Pressure Science and Technology Advanced Research, 1690 Cailun Rd. Pudong, Shanghai 201203, People's Republic of China
2. The Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, California 94720, USA
3. SPring-8/JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
4. Shanghai Institute of Ceramics, Chinese Academy of Sciences, No. 215 Chengbei Road, Jiading District, Shanghai 201800, People's Republic of China
5. Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA