1. Research Institute for Energy Conversion, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba 305-8564, Japan
2. Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94551, United States
3. Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan