1. Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603, Japan
2. Department of Materials Science and Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
3. Electric Power Engineering Research Laboratory, Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196, Japan
4. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan