1. Research Center for Functional Materials, National Institute for Materials Science (NIMS), Namiki, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
2. Research Center for Advanced Measurement and Characterization, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
3. Transmission Electron Microscopy Analysis Station, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan