Effects of the Orientation of [B5O11]7– Fundamental Building Blocks on Layered Structures Based on the Pentaborates

Introduction of the [B-O/F] Units Enhances the Band Gap and Birefringence from Na6Mg3B10O18F6 to K3NaB10O16F2

The borate family is the main source of deep-ultraviolet (DUV) birefringent crystals, and it has attracted a lot of attention due to versatile [B-O] basic units. Herein, two new borate-based compounds Na₆Mg₃B₁₀O₁₈F₆ and K₃NaB₁₀O₁₆F₂ were discovered. Their fundamental building blocks are [B₅O₁₁] and [B₅O₁₀F] units, respectively. The calculated results showed that the band gap and birefringence of K₃NaB₁₀O₁₆F₂ (E_g = 6.93 eV, Δn = 0.047 at 1064 nm) are greater than those of Na₆Mg₃B₁₀O₁₈F₆ (E_g = 5.40 eV, Δn = 0.039 at 1064 nm). Furthermore, the effects of [B-O/F] units on band gap and birefringence were analyzed by the charge-transfer model and response electron distribution anisotropy method. The results show that introducing the [B-O/F] units can improve the band gap and birefringence. These findings will boost the exploration of DUV birefringent opticals.

Pb2Al2B3O8F3: Structure and Properties of a New Fluoroaluminoborate with Non-traditional Chain-like B3O8 Group

A new fluoroaluminoborate, Pb2Al2B3O8F3, with a non-traditional chain [B3O8]7- was synthesized by high temperature reactions in closed systems for the first time. Different from the traditional [B3O8]7- ring [(3:Δ +...

Li3La2(BO3)3 and Li1.75Na1.25La2(BO3)3: A Great Enhancement in Birefringence Induced by Optimal Arrangement of π-Conjugated [BO3] Units

In virtue of the essential role in controlling polarized light, outstanding ultraviolet (UV) and deep-ultraviolet (DUV) birefringent crystals are imperative in many advanced optical instruments. To design the UV and DUV crystals with large birefringence, we paid more attention to combining the excellent gene, π-conjugated [BO₃] unit and metal cations beneficial to blue-shift the cutoff edge; finally, two rare-earth borates Li₃La₂(BO₃)₃ and Li_1.75Na_1.25La₂(BO₃)₃ have been synthesized using the high-temperature solution method. Compared with Na₃La₂(BO₃)₃, Li₃La₂(BO₃)₃ and Li_1.75Na_1.25La₂(BO₃)₃ are isostructural, and the isolated [BO₃] units are arranged nearly parallel to each other in the structure, which is conducive to generating a larger birefringence. The structural comparison between the two crystals and Na₃La₂(BO₃)₃ indicates that the various coordination environments of alkali metal cations play an important role in the evolution of the crystal structure from Li₃La₂(BO₃)₃ and Li_1.75Na_1.25La₂(BO₃)₃ to Na₃La₂(BO₃)₃. This work can contribute to a better understanding of the enhancement in birefringence from Na₃La₂(BO₃)₃ (0.023 @ 1064 nm) to Li₃La₂(BO₃)₃ (0.078 @ 1064 nm) with the perspective of structure-property relationships. Meanwhile, the two title crystals possess the DUV cutoff edge (<190 nm), suggesting that they can be applied as the DUV birefringent crystals.

Gadolinium-Rich Borate Gd17.33(BO3)4(B2O5)2O16 Exhibiting a Magnetocaloric Effect

A gadolinium-rich borate Gd_17.33(BO₃)₄(B₂O₅)₂O₁₆ was successfully grown by the high-temperature solution method using the Rb₂O-B₂O₃ flux. The crystal crystallizes in centrosymmetric space group C2/m with lattice constants a = 18.4300(2) Å, b = 3.7400(4) Å, c = 14.2047(16) Å, and β = 119.8550(12)°. Two different honeycomb-like [GdO] layers alternately arrange in the order ABAB forming the three-dimensional framework, in which the isolated [B₂O₅] and [BO₃] units fill in channels of the 12-membered and 10-membered [GdO] polyhedral rings, respectively. The UV cutoff edge of Gd_17.33(BO₃)₄(B₂O₅)₂O₁₆ is less than 240 nm. The maximum -ΔS_m,max is 26.53 J kg^-1 K^-1 or 174.70 mJ cm^-3 K^-1 (T = 4.4 K and ΔH = 7 T) as investigated by the isothermal magnetization method.

Al8(BO3)4(B2O5)F8: A F-Containing Aluminum Borate Featuring Two Types of Isolated B-O Groups

Al₈(BO₃)₄(B₂O₅)F₈, as a new aluminum borate fluoride, has been synthesized by the high-temperature reaction with the closed system for the first time. With respect to its structure, the isolated BO₃ and B₂O₅ groups reside in the center and edge of tunnels constructed by the AlO₄F₂ polyhedra. The AlO₄F₂ polyhedra play the vital role on the formation of isolated B-O groups. According to our investigation, Al₈(BO₃)₄(B₂O₅)F₈ is the first case, which features two types of independently isolated B-O groups in the aluminum borate fluorides. Its cutoff edge is up to deep ultraviolet (DUV) range. What is more, the energy dispersive spectroscopy (EDS), infrared (IR) spectrum, and the first-principles calculations of Al₈(BO₃)₄(B₂O₅)F₈ have been performed.

From BaAl2(BO3)2O to SnAl2(BO3)2F2: structure transformation based on ion regulation

Sn atoms reside in each Al–B–O–F channel consisting of Al₈B₈O₃₂F₁₂ cavities, which makes SnAl₂(BO₃)₂F₂ possess a special structure.

Synthesis and characterization of three new rare-earth orthoborates: Ba2MgY2(BO3)4, Ba2CdY2(BO3)4, and Ba2CdSc(BO3)3

Three rare-earth orthoborates Ba₂MgY₂(BO₃)₄, Ba₂CdY₂(BO₃)₄, and Ba₂CdSc(BO₃)₃ were synthesized via a high-temperature solution method and their structures were determined by single crystal X-ray diffraction for the first time.

Growth, Crystal Structures, and Characteristics of Li5ASrMB12O24 (A = Zn, Mg; M = Al, Ga) with [MB12O24] Frameworks

Two aluminoborates (Li₅ZnSrAlB₁₂O₂₄ and Li₅MgSrAlB₁₂O₂₄) and one galloborate (Li₅ZnSrGaB₁₂O₂₄) were successfully obtained for the first time, and the centimeter-sized crystals were grown by the Kyropoulos method. These crystals possess the [MB₁₂O₂₄] (M = Al, Ga) basic frameworks in their crystal structures, and the [GaB₁₂O₂₄] framework is a new framework in galloborates. The synthesis, single crystal growth, characterizations, and theoretical calculation are reported for these compounds.

Ba3B10O17F2·0.1KF: the first mixed alkali/alkaline-earth metal fluorooxoborate with unprecedented double-layered B–O/F anionic arrangement

The first mixed alkali/alkaline-earth metal fluorooxoborate Ba₃B₁₀O₁₇F₂·0.1KF with a unique double-layered B–O/F anionic framework was successfully synthesized and systemically characterized.

Mg(H2O)6B4O5(OH)4(H2O)3: a new hydrated borate with a short DUV cutoff edge

[B₄O₅(OH)₄] groups are linked together by hydrogen bonds forming undulating pseudo layers, leading to a short cutoff edge.

Two alkali calcium borates exhibiting second harmonic generation and deep-UV cutoff edges

KCa₄B₃O₉ and K_0.59Rb_0.41Ca₄B₃O₉ crystallize in the polar space group with moderate SHG responses. Calculations were performed to elucidate the structure–property relationships.

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.

MBaYB6O12(M = Rb, Cs): two new rare-earth borates with large birefringence and short ultraviolet cutoff edges

MBaYB₆O₁₂(M = Rb, Cs), two new promising birefringent materials with large birefringence and short UV cutoff edges.

The structural diversity of halogen-centered secondary building units: two new mixed-metal borate halides with deep-ultraviolet cut-off edges

Categories of halogen-centered SBUs were investigated among borates to elaborate the role of halogen to enrich the structural diversity of borates.

Ban+2Znn(BO3)n(B2O5)Fn(n = 1, 2): new members of the zincoborate fluoride series with two kinds of isolated B–O units

Two new zincoborate fluorides were firstly reported containing isolated [BO₃]³⁻and [B₂O₅]⁴⁻groups, which are the first examples of two kinds of isolated B–O groups that coexist in one zincoborate halide.