CsBa2 ScB8 O16: 首例结构中同时含有零维[B3 O6] 基元和一维B--O 链的稀土硼酸盐

The first rare-earth borate crystal CsBa2 ScB8 O16 with both zero-dimensional [B3 O6] units and one-dimensional B--O chain structures has been synthesized by the high-temperature solution method. It crystallizes in the triclinic crystal system with the P1 space group, with lattice parameters of a =6.698 5 Å, b =7.216 Å, c =14.798 Å, α =97.563°, β =95.226°, γ = 95. 546°, Z = 2. In this compound, [BO3] and [B4 O9] units are connected by sharing oxygen atoms to form a onedimensional chain [B5 O10]∞. Octahedrally coordinated [Sc(1)O6] groups and the one-dimensional chain [B5 O10]∞ are further connected by sharing oxygen atoms to form two-dimensional layer [Sc(1) (B4 O9)]∞. Interlayers are linked by octahedrally coordinated [Sc(2)O6] groups, which share oxygen atoms to form a three-dimensional Sc--B--O framework. Isolated [B3 O6] units are filled in the three-dimensional channels with Cs+ and Ba2 + to balance the charges. In order to further explore the novelty of the structure of CsBa2 ScB8 O16, we compared it with other rare-earth borates containing alkali or alkaline-earth metals, and discuss the effect of the cation-to-boron molar ratio (n(A) / n(B)) on the degree of polymerization of B--O units, as well as the dimensionality of the B--O anion framework. Furthermore, the first-principles calculations, infrared spectrum, UV-vis-NIR diffuse reflectance spectrum and the thermal analysis of the compounds have also been performed. Property measurements show that CsBa2 ScB8 O16 exhibits short UV absorption edge (< 190 nm) and moderate birefringence (0. 072@1 064 nm). The optical properties of the compound are mainly contributed by the [B3 O6], [B5 O10] units, and [ScO6] octahedra. [ABSTRACT FROM AUTHOR]