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Updated: Jun 19, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
A Rare-Earth-Based Borate Optical Crystal with Enlarged Dihedral Angles of Distinct [BO3] Groups Exhibiting a Wide UV
Jie Song1, Xianghao Kong1, Conggang Li1,2
1Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystal, Tianjin University of Technology, Tianjin 300384, China.
Abstract:
Borates, as advanced optical materials, have garnered wide interest due to their diverse structural configurations and great potential for applications in the ultraviolet (UV) regions. Herein, we synthesized a new rare-earth borate crystal, namely, K2NaYB2O6, which is classified as one of the ABReB2O6 compounds, where A and B represent alkali metal and Re denotes rare-earth metal. K2NaYB2O6 adopts in the monoclinic space group P21/c (No. 14), showcasing a three-dimensional (3D) framework composed of a planar triangular configuration of [BO3] units and distortive [YO7] polyhedra. Notably, both dihedral angles between distinct [BO3] units reach 79.6°, which represents an unprecedented structural feature in monoclinic ABReB2O6-type crystals. Moreover, the compound has a short UV absorption edge at around 204 nm, corresponding to a wide band gap of approximately 5.67 eV. Additionally, it possesses a moderate birefringence of 0.028 at 1064 nm. Further analysis utilizing theoretical calculations suggests that the optical behaviors of K2NaYB2O6 are mainly governed by its basic structural unit [BO3] triangles and distorted [YO7] polyhedra. These findings enrich the structure chemistry of rare-earth borates and offer valuable insights for the design of optical crystals in the UV wavelength range.
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