1. Department of Physical ChemistrySchool of Metallurgical and Ecological EngineeringUniversity of Science and Technology Beijing No. 30, Xueyuan Road, Haidian District Beijing 100083 P. R. China
2. State Key Laboratory of Biochemical EngineeringInstitute of Process EngineeringChinese Academy of Sciences 1 North 2nd Street, Zhongguancun, Haidian District Beijing 100190 P. R. China
3. Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences 8 South 3rd Street, Zhongguancun, Haidian District Beijing 100190 P. R. China
4. State Key Laboratory of Rare Earth Resource UtilizationChangchun Institute of Applied ChemistryChinese Academy of Sciences No. 5625, Ren Min Street Changchun 130022 P. R. China