**Acknowledgments**

The author thanks Prof. M. Morinaga of Nagoya University for his valuable comments and discussion, Prof. K. Sasaki of Nagoya University for his help with the TEM investigation, and Prof. H. Hosoda and Dr. T. Inamura of Tokyo Institute of Technology for their helpful discussions and XRD investigation. This study was supported by a Grant-in-Aid for Scientif‐ ic Research from the Ministry of Education, Culture, Science, Sports and Culture of Japan, and by the Science and Technology Developing Fund (STDF) of Egypt.
