1. Solid State Microstructure National Key Lab and Collaborative Innovation Center of Advanced MicrostructuresNanjing University Nanjing 210093 China
2. National Center of Electron MicroscopyMolecular FoundryLawrence Berkeley National Laboratory Berkeley CA 94720 USA
3. Department of Materials Science and EngineeringUniversity of California Berkeley CA 94720 USA
4. Erich Schmid Institute of Materials ScienceAustrian Academy of Sciences Jahnstrasse 12 8700 Leoben Austria
5. Department of Materials Science and NanoEngineeringRice University Houston TX 77251 USA
6. Center for High Pressure Science and Technology Advanced Research Shanghai 201203 China