Structural Insights into Borates with an Anion-Templated Open-Framework Configuration: Asymmetric K2 BaB16 O26 versus Centrosymmetric K3 CsB20 O32 and Na2 M2 NB18 O30 (M=Rb, Cs; N=Ba, Pb)

Na2SrB16O26: a new borate with independent interpenetrating B-O networks and deep-ultraviolet cutoff edge

A new borate, Na₂SrB₁₆O₂₆, was synthesized by the high-temperature solution method. It exhibits complicated interpenetrating 3D B-O frameworks composed of the functional building block (FBB) [B₈O₁₆]. The UV-vis-NIR diffuse reflectance spectroscopy shows that it has a deep-ultraviolet (DUV) cutoff edge (<200 nm). The relationship between the structures and optical properties was uncovered by theoretical calculations. By the first-principles calculation, the birefringence is estimated to be 0.07 at 1064 nm. The response electron distribution anisotropy (REDA) analysis indicates that the [BO₃] units contribute mainly to the generation of the moderate birefringence.

Ba10LuB18O32F13: the first example of borate in the Lu–B–O–F system with the unprecedented FBB [B9O22]

The first example of borate in the Lu–B–O–F system was demonstrated, possessing a short cut-off edge near 190 nm and the novel FBB [B9O22].

Ba2.5Pb1.5B12O22: structural transformation from a centrosymmetric to a noncentrosymmetric space group by introducing Pb into Ba2B6O11

A new congruent-melting lead barium borate, Ba_2.5Pb_1.5B₁₂O₂₂, was synthesized via a high-temperature solid-state reaction under atmospheric pressure. It crystallizes in the noncentrosymmetric space group Cmc2₁ with a unit cell of a = 19.051(8) Å, b = 10.726(3) Å, c = 8.612(3) Å, and Z = 4. It features a new functional building block (FBB), [B₁₂O₂₆]^16-, that is made up of five [B₃O₈]^7- and one [BO₃]^3- connected by sharing vertex O atoms. It is derived by introducing Pb into Ba₂B₆O₁₁, which leads to a structural transformation from a centrosymmetric to a noncentrosymmetric space group. Its second harmonic generation response (SHG) is approximately 0.9 times that of KDP at the fundamental wavelength of 1064 nm and is also phase-matchable. It has a wide transparent region with a UV cutoff edge of about 250 nm according to the reflectance spectra and high thermal stability, which illustrates that it is a potential candidate for ultraviolet nonlinear optical materials.

The First Mixed Calcium Zinc Borate with a Flexible [B8 O17 ] Fundamental Building Block and Short UV Cutoff Edge

The first mixed calcium zinc borate with a new fundamental building block (FBB) [B₈ O₁₇ ], Ca_1.13 Zn_0.87 B₈ O₁₄ has been successfully synthesized. It exhibits two independent interpenetrating three-dimensional B-O anion networks constructed by [B₈ O₁₇ ] groups, enriching the structural diversity of B-O configurations. In particular, the UV-Vis-NIR diffuse-reflectance spectrum shows that it has a short UV cutoff edge (<195 nm).

Synthesis, crystal structure and theoretical calculations of two rare-earth borates with DUV cut-off edges

Two isomorphic rare-earth borate crystals, YZnB₅O₁₀ and GdZnB₅O₁₀, show three-dimensional structures constructed from two-dimensional {[B₅O₁₀]⁵⁻}_n layers with the Y or Gd, and zinc ions filled in the interlayers, and exhibit DUV cut-off edges (<190 nm).

Effect of anion dimensionality on optical properties: the ∞[B7O10(OH)2] layer in CsB7O10(OH)2vs. the ∞[B7O12] framework in CsBaB7O12

CsB₇O₁₀(OH)₂ with new FBB features a 2D anionic structure whose band gap is about 6.6 eV and CsBaB₇O₁₂ features a 3D anionic structure whose band gap is 5.6 eV. And their simulated birefringence are about 0.08 and 0.05 at 1064 nm, respectively.

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.

LiCs2La(BO3)2 and Li3K9La3(BO3)7: new mixed alkali metal lanthanum borates with three-dimensional open frameworks and short cut-off edges

Two new mixed alkali metal lanthanum borates, LiCs₂La(BO₃)₂ and Li₃K₉La₃(BO₃)₇, were synthesized through a high-temperature solution method and millimeter-sized colorless crystals were obtained. The structures of LiCs₂La(BO₃)₂ and Li₃K₉La₃(BO₃)₇ have an intricate three-dimensional (3D) open framework with one-dimensional (1D) infinite channels surrounded by cation polyhedra and isolated BO₃ units. In particular, LiCs₂La(BO₃)₂ exhibits a short cut-off edge <190 nm and a large experimental band gap of 6.20 eV, evidenced by diffuse reflection spectroscopy. Moreover, to better understand the relationship between the electronic structures and optical properties of LiCs₂La(BO₃)₂, theoretical calculations using density functional theory were performed. The result indicated that LiCs₂La(BO₃)₂ has a calculated birefringence of 0.036@1064 nm and the direct band gap is 4.54 eV. In addition, the effects of ion substitution on structural transition and the metal ion/boron ratio on dimensions of the B-O frameworks are also discussed in detail.

Structural insights into T2-cluster-containing chalcogenides with vertex-, edge- and face-sharing connection modes of NaQ6 ligands: Na3ZnMIIIQ4 (MIII = In, Ga; Q = S, Se)

New series of T₂-cluster-containing chalcogenides exhibiting the novel connection mode of NaS₆ ligands and torsional adjacent T₂-clusters were reported.

The first lead fluorooxoborate PbB5O8F: achieving the coexistence of large birefringence and deep-ultraviolet cut-off edge

The first lead fluorooxoborate was synthesised as a potential birefringent material, which achieved the coexistence of large birefringence and short cut-off edge.

Ion-induced structural and optical performance evolution in LBO-like crystals: experimental and theoretical investigation

A new alkali metal borate fluoride Li₃KB₉O₁₅F has been obtained for the first time with a UV cut-off edge below 175 nm.