Three Polyborates with High-Symmetry [B12O24] Units Featuring Different Dimensions of Anion Groups

Three polyborates, namely, LiNa₁₁B₂₈O₄₈, Li_1.45Na_7.55B₂₁O₃₆, and Li₂Na₄Ca₇Sr₂B₁₃O₂₇F₉, were synthesized via the high-temperature solution method. All of them feature high-symmetry [B₁₂O₂₄] units, yet their anion groups exhibit distinct dimensions. LiNa₁₁B₂₈O₄₈ features a three-dimensional anionic structure of ³[B₂₈O₄₈]_∞ framework, which is composed of three units: [B₁₂O₂₄], [B₁₅O₃₀], and [BO₃]. Li_1.45Na_7.55B₂₁O₃₆ possesses a one-dimensional anionic structure of ¹[B₂₁O₃₆]_∞ chain consisting of [B₁₂O₂₄] and [B₉O₁₈] units. The anionic structure of Li₂Na₄Ca₇Sr₂B₁₃O₂₇F₉ is composed of two zero-dimensional isolated units, namely, [B₁₂O₂₄] and [BO₃]. The novel FBBs [B₁₅O₃₀] and [B₂₁O₃₉] are present in LiNa₁₁B₂₈O₄₈ and Li_1.45Na_7.55B₂₁O₃₆, respectively. The anionic groups in these compounds exhibit a high degree of polymerization, thereby augmenting the structural diversity of borates. And the crystal structure, synthesis, thermal stability, and optical properties were meticulously discussed to guide the synthesis and characterization of novel polyborates.

Data Mining and Graph Network Deep Learning for Band Gap Prediction in Crystalline Borate Materials

Crystalline borates are an important class of functional materials with wide applications in photocatalysis and laser technologies. Obtaining their band gap values in a timely and precise manner is a great challenge in material design due to the issues of computational accuracy and cost of first-principles methods. Although machine learning (ML) techniques have shown great successes in predicting the versatile properties of materials, their practicality is often limited by the data set quality. Here, by using a combination of natural language processing searches and domain knowledge, we built an experimental database of inorganic borates, including their chemical compositions, band gaps, and crystal structures. We performed graph network deep learning to predict the band gaps of borates with accuracy, and the results agreed favorably with experimental measurements from the visible-light to the deep-ultraviolet (DUV) region. For a realistic screening problem, our ML model could correctly identify most of the investigated DUV borates. Furthermore, the extrapolative ability of the model was validated against our newly synthesized borate crystal Ag₃B₆O₁₀NO₃, supplemented by the discussion of an ML-based material design for structural analogues. The applications and interpretability of the ML model were also evaluated extensively. Finally, we implemented a web-based application, which could be utilized conveniently in material engineering for the desired band gap. The philosophy behind this study is to use cost-effective data mining techniques to build high-quality ML models, which can provide useful clues for further material design.

Li6.58Na7.43Sr4(B9O18)(B12O24)Cl: Unprecedented combination of the largest two highly polymerized isolated B-O Clusters with novel isolated B9O18 FBB

A new borate, Li6.58Na7.43Sr4(B9O18)(B12O24)Cl (LNSBOC), is successfully obtained by spontaneous crystallization method in an open system. LNSBOC crystallizes in a hexagonal crystal system with the centrosymmetric space group of P63/m,...

Sr3B14O24: a new borate with a [B14O30] fundamental building block and an unwonted 2D double layer

A new alkaline-earth metal borate, Sr₃B₁₄O₂₄, was successfully synthesized by a high-temperature solution method. It crystallizes in the monoclinic space group P2₁/c (no. 14) and features a fundamental building block (FBB) [B₁₄O₃₀] which is composed of eight [BO₃] and six [BO₄] units. The FBBs further condense to form an unwonted infinite 2D double layer extended in the bc plane. The UV-Vis-NIR diffuse reflectance spectrum shows that the cutoff edge of Sr₃B₁₄O₂₄ is less than 200 nm, which indicates its potential use in the deep UV region. In addition, the first principles theoretical study was carried out to better understand the relationship between the structure and performance.

M(B(SeO3)3)H2O (M = Al, Ga): the first boroselenites with a unique sandwich like double-layer structure

Exploration of new types of borates is important because of their promising applications in diverse fields. Two new boroselenites, namely, M(B(SeO₃)₃)H₂O (M = Al, Ga), which represent the first IIIA metal boroselenite, were synthesized by hydrothermal reactions. M(B(SeO₃)₃)H₂O (M = Al, Ga) possesses a unique sandwich like double-layer structure formed by two 2D [MSe₂O₈]^5- layers interconnected by 1D [BSeO₅]^3- chains. More interestingly, both compounds display large band gaps (4.86/4.79 eV) and moderate birefringences (Δn = 0.063/0.064 at 1064 nm) based on density functional theory (DFT) calculations.

Identical in Formula but Not Isotypic in Configuration: Discovery of a New Highly Polymerized [B12O24] Cluster in Cs3AlB6O12

The discovery of new borates with unique structures has always been a growing part of solid-state chemistry, especially for polyborates. Herein, a new aluminoborate, Cs₃AlB₆O₁₂, has been discovered by a high-temperature solution in a vacuum system. The highly polymerized [B₁₂O₂₄] cluster, unlike the annular configuration in previously reported polyborates, is found in Cs₃AlB₆O₁₂ for the first time. The different linkage reflected by the local symmetry in cluster makes these borates not isotypic, although the formula of [B₁₂O₂₄] is identical. Experimental measurement performed on Cs₃AlB₆O₁₂ powder reveals the deep-ultraviolet transparent spectral feature.

Cs2AlB5O10: a short-wavelength nonlinear optical crystal with moderate second harmonic generation response

A new compound Cs₂AlB₅O₁₀ was synthesized by a high temperature solution method in open air. It features a DUV cutoff edge below 190 nm and a moderate SHG response (0.8 × KDP at 1064 nm), indicating that it may have certain application prospects in the UV nonlinear optical region.

Three mixed-alkaline-metal borates with {Li@B12Ox(OH)24−x} (x = 18, 22) clusters: from isolated oxoboron cluster to unusual layer

The isolated {Li@B12O18(OH)6} clusters are extended to the {Li@B12O22(OH)2} layer through condensation reactions for the first time.

Five new rubidium borates with 0D clusters, 1D chains, 2D layers and 3D frameworks

By tuning the synthetic conditions, borates with 0D clusters were transformed into a 1D chain, 2D layer and 3D framework.

Sr[B(OH)4](IO3) and Li4Sr5[B12O22(OH)4](IO3)2: two unprecedented metal borate-iodates showing a subtle balance of enlarged band gap and birefringence

Two unprecedented metal borate-iodates, Sr[B(OH)₄](IO₃) (SBIO) and Li₄Sr₅[B₁₂O₂₂(OH)₄](IO₃)₂ (LSBIO), were synthesized via the strategy of introducing (IO₃)^- into borates. In particular, the LSBIO possessed a new B₁₂O₂₆ fundamental building block (FBB). The two compounds integrated the advantages of both pure iodates and borates, showing enlarged band gaps and birefringence. Moreover, diverse B-O FBBs achieved the modulation of birefringence. This work reported the first two examples of borate-iodates.

Li2Na2[B12O19(OH)2]: a new open framework borate with a pcu-type net constructed from large cyclic dodeca-oxoboron units

A new open-framework borate with a pcu-type net has been made under solvothermal conditions by incorporating large cyclic dodeca-oxoboron clusters.

BaBOF3: a new aurivillius-like borate containing two types of F atoms

A new Aurivillius-like fluorine-containing borate, BaBOF₃, featuring both structural characteristics of borate fluorides and fluorooxoborates has been synthesized.

K11RbB28O48: a new triple-layered borate with an unprecedented [B28O57] fundamental building block

A new borate, K₁₁RbB₂₈O₄₈, featuring an unprecedented [B₂₈O₅₇] fundamental building block and an unusual triple-layered anionic group, has been synthesized.

Effect of cation substitution on structural transition: synthesis, characterization and theoretical studies of NaCa4B3O9, NaCaBO3, NaSrBO3 and Li4CaB2O6

NaCa₄B₃O₉, NaCaBO₃, NaSrBO₃ and Li₄CaB₂O₆ are characterized by single crystal X-ray diffraction. The effect of cations on structural cannot be neglected.

Synthesis, structures, and properties of two magnesium silicate fluorides Mg5(SiO4)2F2 and Mg3SiO4F2

The structural differences of title compounds were investigated, and the related physical properties and theoretical calculations were also reported.

Ba7(BO3)3GeO4X (X = Cl, Br): borogermanate halides with rigid GeO4tetrahedra and flexible XBa6octahedra

An unusual structural transformation occurs between Ba₇(BO₃)₃GeO₄X (X = Cl, Br) and Ba₇(BO₃)₃SiO₄X (X = Cl, Br).

Ba2B10O17: a new centrosymmetric alkaline-earth metal borate with a deep-UV cut-off edge

Ba₂B₁₀O₁₇, a new barium borate, with a band-gap of 5.97 eV, possesses a wide transmission range from 180 to 3000 nm.