Finding the Next Deep-Ultraviolet Nonlinear Optical Material: NH4B4O6F

Rational Design of the First Lead/Tin Fluorooxoborates MB2O3F2 (M = Pb, Sn), Containing Flexible Two-Dimensional [B6O12F6]∞ Single Layers with Widely Divergent Second Harmonic Generation Effects

Molecular engineering design is a productive atomic-scale strategy to optimize crystal structure and develop new functional materials. Herein, the first lead/tin fluorooxoborates, MB₂O₃F₂ (M = Pb, Sn), were rationally designed by employing the nonlinear optical crystal Sr₂Be₂B₂O₇ (SBBO) as a parent model. Compared with the rigid [Be₆B₆O₁₅]_∞ double layers in SBBO, MB₂O₃F₂ have flexible two-dimensional [B₆O₁₂F₆]_∞ single layer, which not only keeps the NLO-favorable layered structure but also overcomes the structural instability issues of SBBO. Both compounds exhibited desired short UV cutoff edge. Interestingly, MB₂O₃F₂ exhibit widely divergent second harmonic responses, although they are isostructural and both contain stereochemically active lone-pair cations. Our first-principles calculations revealed that the SHG difference is mainly attributed to the different anisotropies of Pb and Sn SHG-active orbitals, which make constructive and destructive contributions to the SHG effects in PbB₂O₃F₂ and SnB₂O₃F₂, respectively.

Synthesis, crystal structure and optical properties of a new fluorocarbonate with an interesting sandwich-like structure

A new fluorocarbonate, Na3Zn2(CO3)3F, was synthesized using a subcritical hydrothermal method. Na3Zn2(CO3)3F crystallizes in the space group C2/c with a sandwich-like framework in which the stacked [Zn(CO3)]∞ layers are connected with one another by bridging F atoms and [CO3] groups alternately. Interestingly, each Zn atom is surrounded by one F atom and four O atoms, forming a distorted [ZnO4F] trigonal bipyramid, which is observed for the first time in the carbonate system. Na3Zn2(CO3)3F has high transparency in a wide spectral region ranging from UV to mid IR with a short ultraviolet absorption edge (∼213 nm). First-principles calculations revealed that Na3Zn2(CO3)3F possesses a large birefringence (Δn = 0.11, λ = 589 nm), which is mainly contributed by the coplanar arrangement of [CO3] groups in the ab plane. Na3Zn2(CO3)3F might find applications as a UV birefringence crystal.

RbSe3B2O9(OH) and CsSe3B2O9(OH): one dimensional boroselenite-based anionic frameworks with second harmonic generation properties

Two new alkali boroselenites RbSe3B2O9(OH) and CsSe3B2O9(OH) have been synthesized by traditional solid-state reactions. Single-crystal X-ray diffraction study indicated that they are isostructural and adopt a new type of structure, which crystallizes in the noncentrosymmetric space group P212121. Optical diffuse reflectance spectrum studies emphasized that both are indirect optical transitions with values of 3.79 and 4.17 eV for RbSe3B2O9(OH) and CsSe3B2O9(OH), respectively. Optical analysis revealed a broad transparency window in the 0.3-8.5 μm region for both compounds. In addition, RbSe3B2O9(OH) featured a relatively weak second-harmonic-generation response, and for CsSe3B2O9(OH), the response is 0.8-times that of KH2PO4. Theoretical calculations of band structure, density of state, and linear and nonlinear optical properties were also performed to get insight into the relationships between electronic structures and their optical properties.

M2B10O14F6 (M = Ca, Sr): Two Noncentrosymmetric Alkaline Earth Fluorooxoborates as Promising Next-Generation Deep-Ultraviolet Nonlinear Optical Materials

Two novel noncentrosymmetric alkaline earth fluorooxoborates, M₂B₁₀O₁₄F₆ (M = Ca, Sr), were synthesized and characterized. Both of these two isostructural compounds had layered [B₅O₇F₃]_∞ structures with large second harmonic generation (SHG) responses ranging from 2.3 to 2.5 × KH₂PO₄ (KDP) and short UV absorption edges (<200 nm). The first-principles calculation demonstrated that their nonlinear optical (NLO) properties were superior to those of KBe₂BO₃F₂ (KBBF). In contrast to the alkali fluorooxoborates, these two fluorooxoborates showed not only remarkable stability against air and moisture but also high thermal stability. Therefore, M₂B₁₀O₁₄F₆ (M = Ca, Sr) should be promising deep-ultraviolet (DUV) NLO materials.

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.

Ba3B10O17Br2: a new barium borate halide with B–O layered structure

A new barium borate halide, Ba₃B₁₀O₁₇Br₂, has been obtained, and is the first barium borate halide with a B–O layered structure.

Perfect balance harmony in Ba2NO3(OH)3: a beryllium-free nitrate as a UV nonlinear optical material

Ba₂NO₃(OH)₃ exhibits a perfect balance of a large SHG coefficient, a short UV absorption cutoff edge, an appropriate birefringence, and stable physicochemical properties.

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.

BaLiZn3(BO3)3: a new member of the KBe2BO3F2family possessing dense BO3triangles and the smallest interlayer distance

A new beryllium-free borate, BaLiZn₃(BO₃)₃, featuring dense BO₃triangles and the smallest interlayer distance among KBe₂BO₃F₂derivatives is developed.

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.

K2TeP2O8: a new telluro-phosphate with a pentagonal Te–P–O layer structure

We report a new telluro-phosphate K₂TeP₂O₈ with an analogously pentagonal [TeP₂O₈]²⁻ layer structure.

Four new quaternary chalcogenides A2Ba7Sn4Q16 (A = Li, Na; Q = S, Se): syntheses, crystal structures determination, nonlinear optical performances investigation

Four new quaternary chalcogenides with interesting structures and potential nonlinear optical performances were synthesized for the first time.

Flexible coordination of Pb atoms and variable zinc–borate frameworks to construct three Pb5Zn4B6O18 polymorphs

Three Pb₅Zn₄B₆O₁₈ polymorphs were synthesized and phase transformations were investigated using powder X-ray diffraction, thermal analysis and theoretical simulation.

Crystal engineering, optical properties and electron density distribution of polar multicomponent materials containing sulfanilamide

Combination of qualitative and quantitative crystal engineering tools for efficient design and detailed analysis of novel functional materials.

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.

Pb3(SeO3)Br4: a new nonlinear optical material with enhanced SHG response designedviaan ion-substitution strategy

A new NLO material has been designedviaion-substitution from a similar structure. It shows an enhanced SHG response equalling to that of KH₂PO₄(KDP) and a high laser damage threshold of 67 MW cm⁻¹.

PbFePO4F2 with a 1/6th bond depleted triangular lattice

A 1/6th bond depleted triangular lattice has been experimentally realized in the novel compound PbFePO₄F₂ with moderately strong frustration.

Indium selenide monolayer: a two-dimensional material with strong second harmonic generation

The In₂Se₃ monolayer may be a material with the strongest SHG response among IIIA–VIA semiconductors reported to date.

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.

NH4B11O16(OH)2: a new ammonium borate with wavy-shaped polycyclic 2∞[B11O16(OH)2] layers

The ammonium borate NH₄B₁₁O₁₆(OH)₂ has been successfully synthesized by a mild hydrothermal method.

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.

Ba2ZnSc(BO3)3and Ba4Zn5Sc2(BO3)8: first examples of borates in the Zn–Sc–B–O system featuring special structure configurations

First examples in the Zn–Sc–B–O system featuring a special Zn/Sc–O configuration ([Zn₂(BO₃)₆]¹⁴⁻cluster, lowest-coordinated ScO₅polyhedra, and coexistence of ZnO₄and ZnO₆units).