1. State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering; Tsinghua University; Beijing 100084 China
2. Graduate School at Shenzhen; Tsinghua University; Shenzhen 518055 China
3. Professor Emeritus; Hokkaido University; 228-7399 Nakagawa, Hosoe-cho, Kita-ku Hamamatsu 431-1304 Japan