1. Institute of Applied Chemistry, Shanxi University, Taiyuan 030006, P. R. China
2. National & Local Joint Engineering Research Center for Mineral Salt Deep Utilization, Huaiyin Institute of Technology, Huaian 223003, P. R. China
3. School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
4. Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, P. R. China