1. CGNPC Uranium Resources Co. Ltd, New Physics Research Center, Building 5, Yard 16, Changxing Road, Fengtai District, Beijing 100072, P. R. China
2. New Physics Research Center, Building 5, Yard 16, Changxing Road, Fengtai District, Beijing 100072, P. R. China
3. School of Materials Science and Engineering, Tianjin University, Tianjin, P. R. China