T. Imai, L. Geng, J. F. Mao and I. Tochigi 1) National Industrial Research Institute of Nagoya, 1-1 Hirate-cho, Kita-ku, Nagoya, 462-8510, Japan 2) School of Materials Science & Engineering, Harbin Institute of Technology, Harbin 15001, China 3) Kanagawa High-Technology Foundation, Kanagawa Science Park, 3-2-1, Sakado, Takatsu-ku, Kawasaki, Kanagawa 213, Japan