1. Department of Nanotechnology for Suitable Energy, Graduate School of Science and Technology, Kwansei Gakuin University, 1 Gakuen-Uegahara, Sanda, Hyogo 669-1330, Japan
2. Materials Sciences Research Center, Japan Atomic Energy Agency, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
3. Car and Life-style R&D Division, Daihatsu Motor CO., Ltd., 1-1 Daihatsu, Ikeda, Osaka 563-8651, Japan