1. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
2. University of Science and Technology of China, Hefei 230026, P. R. China
3. School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371
4. Dental Health Department, College of Applied Medical Sciences, King Saud University, Riyadh 11541, Saudi Arabia
5. School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong 529020, P. R. China