CsBa2ScB8O16:the First Rare-Earth Borate Simultaneously Containing Zero-Dimensional[B3O6]Units and One-Dimensional B—O Chains
The first rare-earth borate crystal CsBa2ScB8O16 with both zero-dimensional[B3O6]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 P(1)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[B4O9]units are connected by sharing oxygen atoms to form a one-dimensional chain[B5O10]∞.Octahedrally coordinated[Sc(1)O6]groups and the one-dimensional chain[B5O10]∞ are further connected by sharing oxygen atoms to form two-dimensional layer[Sc(1)(B4O9)]∞.Interlayers are linked by octahedrally coordinated[Sc(2)O6]groups,which share oxygen atoms to form a three-dimensional Sc—B—O framework.Isolated[B3O6]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 CsBa2ScB8O16,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 CsBa2ScB8O16 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[B3O6],[B5O10]units,and[ScO6]octahedra.
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