1. Jiangxi Key Laboratory of Nanomaterials and Sensors, Jiangxi Key Laboratory of Photoelectronics and Telecommunication, School of Physics, Communication and Electronics, Jiangxi Normal University, Nanchang 330022, Jiangxi, P. R. China
2. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
3. College of Chemistry and Environment, Yunnan Min Zu University, Kunming 650500, China
4. Physics Department, New Jersey Institute of Technology, Newark, New Jersey 07102-1982 United States
5. Institute of Advanced Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang 330022, Jiangxi Province, China