title: Structure modulations in nonlinear optical (NLO) materials Cs(2)TB4O9 (T = Ge, Si).
abstract: Incommensurately modulated borate structures of a new type were studied in detail in the nonlinear optical (NLO) materials Cs(2)TB4O9 (T = Ge, Si) using single-crystal X-ray diffraction techniques. The structures were solved by the charge-flipping algorithm in the superspace group I2(αβ0)0. The refinement results strongly suggest that the main structure modulation feature of Cs(2)TB4O9 is the ordering of the O atoms. With these modulated structure models, the unreasonable B-O distances in the average structures were explained as the ordering of BO4 and BO3.
authors.affiliation: College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Zhengyang
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Xu
authors.affiliation: College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Rao
authors.initials: R
authors.lastname: Fei
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, People's Republic of China.
authors.forename: Jianggao
authors.initials: J
authors.lastname: Mao
authors.affiliation: College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Junliang
authors.initials: J
authors.lastname: Sun
keywords: borates; incommensurate structure; nonlinear optics; occupancy modulation