1. Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2. Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
3. High Pressure Science and Engineering Center, Department of Physics and Astronomy, The University of Nevada, Las Vegas, Nevada 89154, USA and National Lab for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
4. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA