1. Tianjin Key Laboratory of Chemical Process Safety, School of Chemical Engineering and Technology, Hebei University of Technology, GuangRong Dao 8, Hongqiao District, Tianjin 300130, P. R. China
2. College of Physics Science & Technology, Hebei University, Baoding 071002, China
3. Tianjin Baogang Research Institute of Rare Earths Co., Ltd., Tianjin 300300, China