1. Department of Materials Science and Engineering, University of California 1 , Los Angeles, California 90095, USA
2. Adroit Materials, Inc. 2 , Apex, North Carolina 27518, USA
3. Department of Materials Science and Engineering, North Carolina State University 3 , Raleigh, North Carolina 27606, USA
4. Institute of High Pressure Physics, Polish Academy of Sciences 4 , Warsaw 01-142, Poland
5. Advanced Photon Source, Argonne National Laboratory 5 , Lemont, Illinois 60439, USA