1. Department of Materials Science (Glass and Ceramics), Friedrich-Alexander-Universität of Erlangen-Nürnberg; Martensstr. 5 D-91058 Erlangen Germany
2. Department of Materials Science and Engineering, Nagoya Institute of Technology, Institute of Ceramics Research and Education; Gokiso-cho, Showa-ku Nagoya-shi, Aichi 466-8555 Japan
3. Frontier Research Institute for Materials Science, Nagoya Institute of Technology; Gokiso-cho, Showa-ku Nagoya 466-8555 Japan