1. High pressure group National Institute for Materials Science Namiki 1‐1, Tskuba 305‐0044 Ibaraki Japan
2. Widegap semiconductor group National Institute for Materials Science Namiki 1‐1, Tskuba 305‐0044 Ibaraki Japan
3. Department of Materials Science Osaka Prefecture University 1‐1 Gakuencho, Naka‐ku 599‐8531 Sakai Osaka Japan
4. Department of Applied Chemistry Chubu University 1200 Matsumoto 487‐8501 Kasugai Aichi Japan