1. Center for Advanced Research of Energy Conversion Materials, Hokkaido University, N13 W8 Kita-ku,
Sapporo 060-8628, Japan
2. Energy Reserch Institute, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba 305-8569, Japan
3. Department of Materials Science and Engineering, Kyushu University, 744 Motooka, Nishi-ku,
Fukuoka 819-0395, Japan