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Abstract: The title compound was firstly synthesized by solid state reaction and its single crystals were successfully obtained using a selected flux. It is isotypic with the mineral buetschliite, K2Ca(CO3)2, and crystallizes in the trigonal space group R-3m with a = 5.4526(12) Å, c = 17.781(8) Å, Z = 3. In the structure, Ba and K atoms are disordered on a same site in the proportion of 0.492(4):0.508(4). The fundamental building units are YO6 octahedra and BO3 triangles. The structure consists of [YB2O6]∞ double layers constructed by corner-sharing YO6 and BO3 groups. Ba/K atoms occupy the spaces between these two layers and play the role of bridges. In addition, the luminescence properties of Eu3+ doped KBaY(BO3)2 were also studied. [Copyright &y& Elsevier]

Perovskite compounds are always the focus in the material research field. Herein, the polycrystalline samples and single crystals of Na 2 ZrTeO 6 , a B-site ordered double-perovskite compound, were prepared successfully. Single crystal X-ray diffraction demonstrated that Na 2 ZrTeO 6 crystallizes in the cubic space group Fm-3m (No. 225) with unit parameters of a = b = c = 7.80360(10) Å. The crystal structure of Na 2 ZrTeO 6 , formed by ZrO 6 and TeO 6 octahedra through sharing the corner oxygen atoms, belongs to the typical rock-salt-type perovskite structure. The density functional theory calculations show that Na 2 ZrTeO 6 has a direct band gap with band gap of 3.21 eV, which is lower than the experimental value of 3.85 eV. Interestingly, the powder samples of Na 2 ZrTeO 6 exhibit a self-activated near-infrared emission centered at 780 nm under ultraviolet light excitation. And a strong luminescence thermal stability was also observed. Compared to room temperature, the luminescence intensity can maintain 64 % at 200 °C. [Display omitted] • The high-purity double-perovskite Na 2 ZrTeO 6 samples were synthesized by wet chemical method. • Structure analysis indicate that Na 2 ZrTeO 6 belongs to the typical rock-salt-type perovskite structure. • Na 2 ZrTeO 6 exhibits self-activated near-infrared emission centered at 780 nm excited by 308 nm. • The sample's emission intensity maintained 64 % of its room temperature peak intensity at 200 °C. [ABSTRACT FROM AUTHOR]