1. Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
2. Institute of Industrial Nanomaterials, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
3. Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
4. Technical Division, Kumamoto University, 2-39-1 Kurokami, Chuo, Kumamoto 860-8555, Japan
5. Mitsui Mining & Smelting Co., Ltd., Ageo, Saitama 362-0021, Japan