Affiliation: | 1. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1‐1 Namiki, Tsukuba, Ibaraki 305‐0044 (Japan), Fax: (+81)?29‐854‐9061;2. Permanent address: Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China) |