[1] Chiba Univ, Fac Sci, Chiba 263, Japan
[2] Univ Tsukuba, Inst Appl Phys, Tsukuba, Ibaraki 305, Japan
[3] Nagoya Inst Technol, Ceram Res Lab, Tajimi 507, Japan
[4] Nagoya Inst Technol, Showa Ku, Nagoya, Aichi 466, Japan
[5] Kwansei Gakuin Univ, Sch Sci, Nishinomiya, Hyogo 662, Japan
[6] Japan Atom Energy Res Inst, Dept Mat Sci & Engn, Tokai, Ibaraki 31911, Japan
[7] JAERI SPring 8, Ako, Hyogo 67812, Japan