1. Institute of Materials Science and Engineering & School of Science and Engineering of Mathematics and Physics, Anhui University of Technology, Maanshan 243032, Anhui Province, P. R. China
2. Institute of Physics and Optoelectronic Technology, Baoji University of Arts and Sciences, Baoji 721000, Shanxi Province, P. R. China
3. Anhui Province Key Laboratory of Metallurgical Engineering & Resources Recycling, Anhui University of Technology, Maanshan 243002, Anhui Province, P. R. China