1. Contribution from the Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan, Department of Materials Chemistry, Hosei University, Kajino-cho, Koganei-shi, Tokyo 184-8584, Japan, and Graduate School of Science, Tokyo Metropolitan University, Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan