1. Nano Ceramics Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
2. Particle Technology Laboratory, Department of Mechanical Engineering, ETH Zürich, CH-8092 Zürich, Switzerland
3. Superconducting Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
4. International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan, and Department of Chemical Science and Technology, Hosei University, Koganei, Tokyo 184-8584, Japan