1. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
2. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. Center for Nanoscale Materials, Nanoscience and Technology, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
5. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
6. National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
7. National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
8. Nanjing University of Posts and Telecommunications, Nanjing 210023, P. R. China
9. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China