Borates are one of the most important classes of functional materials, and several hundreds of artificial borates have been synthesized. The substitution of oxygen by fluorine leads to manifold classes of borates. Fluorooxoborates (also known as fluoroborates), in which the F atoms covalently connect with the B atoms, show additional compositional and structural diversity compared to classic borates. Recently, owing to the large polarizability anisotropy, large HOMO–LUMO gaps, and high hyperpolarizability of the oxyfluoride BO_xF_4−x building blocks, fluorooxoborates have received unprecedented attention in the search for new ultraviolet (UV) and deep‐UV (DUV) nonlinear optical (NLO) materials. Specifically, some compounds have excellent NLO properties that are comparable or superior to KBe₂BO₃F₂, which is the only usable crystal that generates coherent light below 200 nm through a direct second harmonic generation (SHG) process. This Minireview illustrates recent progress on the synthesis, crystal structures, structure‐properties relationships and applications of fluorooxoborates. This paper concludes by highlighting the outstanding opportunities offered by NLO fluorooxoborate crystals as an innovative avenue for DUV all solid‐state coherent light generation.

中文翻译：

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氟氧硼酸盐：开创了深紫外非线性光学材料的新时代

硼酸盐是功能材料中最重要的一类，并且已经合成了数百种人工硼酸盐。用氟取代氧会导致硼酸盐的种类繁多。与经典硼酸盐相比，氟原子（也称为氟硼酸盐）（其中F原子与B原子共价连接）显示出额外的组成和结构多样性。最近，由于大的极化率各向异性，大的HOMO-LUMO间隙和氟氧化物BO _x F _{4- x的}高超极化率在寻找新的紫外线（UV）和深紫外线（DUV）非线性光学（NLO）材料方面，含氟硼酸盐已受到前所未有的关注。具体而言，某些化合物具有与KBe ₂ BO ₃ F ₂相当或更高的出色的NLO性质，后者是唯一可通过直接二次谐波生成（SHG）工艺在200 nm以下产生相干光的晶体。这份小型综述说明了氟代草酸盐的合成，晶体结构，结构-性能关系及其应用方面的最新进展。本文最后着重介绍了NLO氟硼酸盐晶体作为DUV全固态相干光产生的创新途径所提供的绝佳机会。