1. Department of Applied Chemistry
2. Kagami Memorial Laboratory for Materials Science and Technology
3. Advanced Research Center for Science and Engineering, Waseda University, Okubo 3‐4‐1, Shinjuku‐ku, Tokyo 169, Japan
4. Hitachi Cable, Limited, System's Material Laboratory, Sukegawa‐cho 3‐1‐1, Hitachi‐shi, Ibaraki‐ken 317, Japan