1. State Key Laboratory of New Ceramics & Fine Processing; School of Materials Science and Engineering; Tsinghua University; Beijing 100084 China
2. Department of Inorganic Nonmetallic Materials; School of Materials Science and Engineering; University of Science and Technology Beijing; Beijing 100083 China
3. School of Scientific Research & Development; Beijing University of Chemical Technology; Beijing 100029 China
4. Tianjin Nitride Advanced Materials Company; Tianjin 300303 China