1. The Institute of Scientific
and Industrial Research, Osaka University, 8-1 Mihogaoka Ibaraki, Osaka 567-0047, Japan
2. State Key Laboratory of High
Performance Ceramics and Superfine Microstructures, Shanghai Institute
of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China
3. Department of Applied Quantum
Physics and Nuclear Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395,
Japan