Metal-free borates have emerged as a new class of solid-state chemistry and related crystalline materials with high performance. However, the discovery of metal-free borate crystals that can meet the phase-matching behavior in the short-wavelength ultraviolet (UV) spectral region is extremely limited. Against this background, two new guanidinium fluorooxoborates with the chemical formula of [C(NH2)3][B3O3F2(OH)2] and [C(NH2)3]2[B3O3F4(OH)] have been discovered and characterized as high-performance candidates for short-wavelength UV nonlinear optical (NLO) applications. The optimally aligned configuration of coplanar [C(NH2)3] cations and [B3O3F2(OH)2]/[B3O3F4(OH)] heteroanionic units makes both crystals have a sufficiently large NLO coefficient, birefringence, and band gap, which indicate that both metal-free hydroxyfluorooxoborates are promising NLO crystals. The well-ordered configurations of OH/F anions in two borates were identified using various approaches, and the origin of high optical performance was validated by additional measurements and calculations. Our findings verified the feasibility of searching NLO crystals in the short-wavelength region in a metal-free borate system via an eco-friendly and low-cost way.
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金属
硼酸盐已成为固态
化学和相关晶体材料中的一类新型高性能材料。然而,能在短波紫外(UV)光谱区满足相匹配行为的无
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硼酸盐晶体的发现却极为有限。在此背景下,我们发现并表征了两种
化学式分别为 [C(NH2)3][B3O3F2(OH)2] 和 [C(NH2)3]2[B3O3F4(OH)] 的新型
胍基
氟氧
硼酸盐,它们是短波紫外非线性光学(NLO)应用的高性能候选物质。共面[C(NH2)3]阳离子和[B3O3F2(OH)2]/[B3O3F4(OH)]杂阴离子单元的最佳排列构型使这两种晶体都具有足够大的 NLO 系数、双折射和带隙,这表明这两种无
金属羟
氟氧
硼烷都是很有前景的 NLO 晶体。我们采用多种方法确定了两种
硼酸盐中 OH/F 阴离子的有序构型,并通过额外的测量和计算验证了高光学性能的来源。我们的研究结果验证了在无
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硼酸盐体系中以环保和低成本的方式寻找短波长区域 NLO 晶体的可行性。