1. State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
2. Department of Physics, Sam Houston State University, Huntsville, Texas 77341, United States
3. Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, United States
4. NSLS, Brookhaven National Laboratory, Upton, New York 11973, United States
5. Yuan Ze Fuel Cell Center/Department of Chemical Engineering and Materials Science, Yuan Ze University, No. 135, Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan