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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 BOxF4−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. In at the deep end: The deep ultraviolet nonlinear optical materials with excellent comprehensive performance are the key for the development of deep ultraviolet all solid‐state lasers. This Minireview focuses on the design strategies, synthetic approaches, crystal chemistry, and structure‐properties relationships of recent research highlight fluorooxoborates. [ABSTRACT FROM AUTHOR]

Abstract: Introducing fluorine into borates indicates the direction for structural evolution. A new fluorooxoborate, NaRbB6O9F2 featuring a unique [B6O9F2]∞ layered structure and excellent optical properties has been synthesized. It is further demonstrated that incorporation of fluorine can enrich the structural chemistry of borates. [ABSTRACT FROM AUTHOR]

Abstract: K3B6O9F3, a first fluorooxoborate containing four different units, that is, [BO3]3−, [BO4]5−, [BO3F]4−, and [BO2F2]3−, has been designed and synthesized by two different routes. The unique anionic 2 ∞ [B6O9F3]3− layers avoid forming terminal oxygen atoms, which are beneficial to enlarge the band gap. The structure‐properties relationship of the title compound is discussed. [ABSTRACT FROM AUTHOR]

Three new carbonate halides, Cs3Pb2(CO3)3I, KBa2(CO3)2F and RbBa2(CO3)2F have been synthesized with hydrothermal and solid-state methods. Cs3Pb2(CO3)3I is the first product in the lead carbonate iodides family; KBa2(CO3)2F and RbBa2(CO3)2F are the first two centrosymmetric compounds found in the alkaline-alkaline earth carbonate fluorides family. Cs3Pb2(CO3)3I crystallizes in a centrosymmetric space group C2/ m, and exhibits a two- dimensional layered structure which is formed by [Cs4Pb4(CO3)6I2]∞ double-layers consisting of [Pb2(CO3)3I]∞ single-layers bridged by the Cs atoms. KBa2(CO3)2F and RbBa2(CO3)2F, which are isostructural, crystallize in a trigonal crystal system with a centric space group of R featuring a honeycomb-like framework. First principle calculations indicate that Cs3Pb2(CO3)3I has a moderate birefringence and explain the difference between the band gaps of the title compounds from electron structures. The effects of cations and halogens on the structures and properties of the title compounds are also discussed. [ABSTRACT FROM AUTHOR]

Borate not graphene: The [B6O12]∞6− single borate layer is a graphene‐like layer (see figure). The weak Na+Br(Cl)− ionic connection between the layers leads to the layer cleavage, and difficulty of the block crystal growth. [ABSTRACT FROM AUTHOR]

Deep ultraviolet nonlinear optical materials with excellent comprehensive performance are the key for the development of deep ultraviolet all solid‐state lasers. This review focuses on the design strategies, synthetic approaches, crystal chemistry, and structure‐properties relationships of recent research highlight fluorooxoborates. Considering the obvious advantages of fluorooxoborates, it is believed that fluorooxoborates will open a new window for deep ultraviolet nonlinear optical materials in near future. For more details, see the Minireview by S. Pan et al. on page 17638 ff. [ABSTRACT FROM AUTHOR]