1. Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
2. Division of Materials Science, Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan
3. Osaka R & D Laboratories, Sumitomo Electric Industries, Limited, 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan