K3BaTeB7O15: A new borotellurite with mixed metal cations

• A novel mixed-metal cation-based borotellurite K 3 BaTeB 7 O 15 was synthesized. • The compound has an anionic framework interconnected by TeO 3 groups and pseudo-layers consisting of B 7 O 16 units. • The electronic energy band structure and partial density of states were calculated and discussed. Tellurium-based borates are known to exhibit good optical properties and structural diversity, which are beneficial for obtaining new multicomponent borate optical materials. Therefore, a new borotellurite K 3 BaTeB 7 O 15 with an anionic framework interconnected by TeO 3 groups and pseudo-layers consisting of B 7 O 16 units, was synthesized. The compound was synthesized by the high-temperature solution method and crystallized in the P 2 1 / c (No.14) space group, which has a complex cation. The UV-–vis–NIR diffuse reflectance spectra showed that the absorption edge of K 3 BaTeB 7 O 15 was approximately at 235 nm, corresponding to a large experimental band gap of 4.2 eV. Thermal property analysis indicated that the compound was stable below 570 °C. The electronic energy band structure and partial density of states were calculated and discussed, and its birefringence was approximately 0.03@1064 nm. The results of ELF prove the existence of the stereochemical activity of the TeO 3 group in K 3 BaTeB 7 O 15 .