[1] Lanzhou Univ, Sch Phys Sci & Technol, Dept Mat Sci, Lanzhou 730000, Peoples R China
[2] Minist Educ, Key Lab Special Funct Mat & Struct Design, Beijing, Peoples R China
[3] Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi, Japan
[4] Osaka Univ, Inst Sci & Ind Res, Suita, Osaka 565, Japan