新型纳米结构Ba2Ni(BO3)2的合成、结构表征、相稳定性及光学性质：面向电子应用的功能性正硼酸盐材料

This work reports the synthesis and comprehensive characterization of the novel orthoborate Ba 2 Ni(BO 3 ) 2 as a potential wide-bandgap material. The compound was successfully synthesized as a single phase via a solid-state route, crystallizing in the rhombohedral R \(\underline{3}\) m space group with refined lattice parameters a = 5.326(6) Å and c = 16.876(2) Å. Fourier-transform infrared (FTIR) analysis confirmed the expected trigonal planar [BO 3 ] 3− units and octahedrally coordinated Ni 2+ through characteristic vibrational modes, as confirmed via the Raman spectroscopy results. Scanning electron microscopy revealed a dense, nanostructured morphology composed of needle-like crystallites. The material demonstrates high thermal stability, retaining its structure up to 600 °C before showing signs of a phase transition at 800 °C. Optical characterization identified characteristic Ni 2+ d–d electronic transitions. Crucially, Tauc analysis of the absorption data revealed a wide direct optical bandgap of 3.95 eV, establishing Ba 2 Ni(BO 3 ) 2 as a promising candidate material for applications in ultraviolet optoelectronics and transparent electronic devices.