1. Nanostructures Research Laboratory, Japan Fine Ceramics Center, Atsuta-ku, Nagoya 456-8587, Japan
2. Advanced Material Engineering Division, Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193, Japan
3. Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
4. Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan