ic5b00926_si_003.cif (25.44 kB)

Two New Crystals in LimCsnBm+nO2(m+n) (m + n = 5, 7; m > n) Series: Noncentrosymmetric Li5Cs2B7O14 and Centrosymmetric Li4CsB5O10

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posted on 03.08.2015, 00:00 by Lin Li, Shujuan Han, Binghua Lei, Xiaoyu Dong, Hongping Wu, Zhongxiang Zhou, Zhihua Yang, Shilie Pan
With the introduction of an alkali metal into the B–O framework, two new alkali metal borate crystals, Li5Cs2B7O14 and Li4CsB5O10, have been obtained for the first time. Both compounds obey a general formula of LimCsnBm+nO2(m+n) (m + n = 5, 7; m > n). The two crystals have different three-dimensional (3D) framework structures composed by LiOn (n = 4, 5), CsO10, BO3, and BO4 units. Li5Cs2B7O14 crystallizes into the polar and noncentrosymmetric space group Ama2, while Li4CsB5O10 belongs to the nonpolar and centrosymmetric space group P21/c. Detailed structure comparison analysis indicates that the different arrangements of the anionic groups in LimCs7–mB7O14 (m = 4, 5) and LimCs5–mB5O10 (m = 3, 4) may arise from the cation size effects, bond-valence requirements, and differences of coordination environment. In addition, in order to get better understandings of electronic structures and linear optical properties, we also carried out first-principle theoretical studies.