1. Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education of the People's Republic of China Heilongjiang University Harbin 150080 P. R. China
2. Key Laboratory of Electronics Engineering College of Heilongjiang Province Heilongjiang University Harbin 150080 P. R. China
3. Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Bejing 100190 P. R. China