1. Department of Materials Science and Engineering, Kyushu Institute of Technology, Kitakyushu, Fukuoka 804-8550, Japan
2. Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
3. The Ultramicroscopy Research Center, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
4. Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu, Fukuoka 804-8550, Japan
5. The Ultramicroscopy Research Center and Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan