State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Dalton Trans. 2023 Apr 4;52(14):4423-4428. doi: 10.1039/d3dt00326d.
A new alkaline earth-rare earth iodate, BaCe(IO)(HO), has been synthesised by a hydrothermal method and its structure has been determined by single-crystal X-ray diffraction. BaCe(IO)(HO) crystallises in the polar space group 2 (No. 33) with unit cell parameters of = 15.5042(5) Å, = 7.8841(3) Å, = 19.5359(8) Å, = 2388.00(15) Å, and = 4. The structure of BaCe(IO)(HO) is characterised by zero-dimensional (0D) [Ce(IO)(HO)] units separated by Ba cations. Large crystals of BaCe(IO)(HO) with dimensions of a few millimetres have been grown. The UV-vis-NIR transmission spectroscopy measurements of the compound showed that it has a short wavelength absorption edge at 381 nm. BaCe(IO)(HO) exhibits a relatively weak second-harmonic-generation (SHG) response, about 0.2 times that of KDP, which is mainly due to the fact that the polarisation effects of the IO groups in the structure largely cancel each other out. The relationships between the structure and the physical properties of BaCe(IO)(HO) have also been calculated theoretically. BaCe(IO)(HO) has a band gap of 2.44 eV, which is determined by the Ce-O and I-O interactions and is larger than those of many simple metal iodates. The introduction of alkaline earth metals favours an increase in band gap. Our work shows that the SHG and birefringence properties are closely related to the arrangement of the functional groups in the compounds.
一种新的堿土-稀土碘酸盐 BaCe(IO)(HO) 已通过水热法合成，并通过单晶 X 射线衍射确定了其结构。BaCe(IO)(HO) 结晶在极性空间群 2（No. 33）中，具有 a = 15.5042(5) Å, b = 7.8841(3) Å, c = 19.5359(8) Å, = 2388.00(15) Å 和 = 4。BaCe(IO)(HO) 的结构由零维（0D）[Ce(IO)(HO)]单元通过 Ba 阳离子隔开。已经生长出几毫米尺寸的 BaCe(IO)(HO)大晶体。该化合物的 UV-vis-NIR 透射光谱测量表明，它在 381nm 处具有短波长吸收边缘。BaCe(IO)(HO) 表现出相对较弱的二次谐波产生（SHG）响应，约为 KDP 的 0.2 倍，这主要是由于结构中 IO 基团的极化效应相互抵消。BaCe(IO)(HO) 的结构与物理性质之间的关系也进行了理论计算。BaCe(IO)(HO) 的带隙为 2.44eV，这是由 Ce-O 和 I-O 相互作用决定的，并且大于许多简单金属碘酸盐的带隙。堿土金属的引入有利于带隙的增加。我们的工作表明，SHG 和双折射性质与化合物中功能基团的排列密切相关。
