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Herein, a new congruently melting mixed-anion compound Cs 4 B 4 O 3 F 10 has been characterized as the first fluorooxoborate with [BF 4 ] involving heteroanionic units. Cs 4 B 4 O 3 F 10 possesses two highly fluorinated anionic clusters and therefore its formula can be expressed as Cs 3 (B 3 O 3 F 6 )·Cs(BF 4 ). The influence of [BF 4 ] units on micro-symmetry and structural evolution was discussed based on the parent compound. More importantly, Cs 4 B 4 O 3 F 10 shows the lowest melting point among all the available borates and thus sets a new record for such system. This work is of great significance to enrich and tailor the structure of borates using perfluorinated [BF 4 ] units.

The generated light can be tuned to cover almost the entire spectral range from deep-ultraviolet to terahertz wavelengths by utilizing the nonlinear optical crystals with a simple frequency doubling process. Among them, the discovery of novel candidates for the production of deep-ultraviolet light is by extension a great challenge toward realizing the vast potential. Actually, the availability for this process mainly depends on whether the critical performance can be well coexisted in one practical crystal. Herein, the first magnesium fluorooxoborate MgB5 O7 F3 was synthesized as a new competitive candidate for deep-ultraviolet nonlinear optical application. It has a sufficiently large nonlinearity and a deep-ultraviolet phase matching wavelength, indicating that it holds great potential for the production of coherent light below 200 nm. The critical performance enhancement of MgB5 O7 F3 when compared with its isomorphic phases was demonstrated and discussed. More importantly, we proposed that fluorooxoborate system with the general formula of MB5 O7 F3 (M=divalent metal) possesses stable fluorine terminated framework, which makes them tend to retain their crystallized space groups unchanged.

Four new alumino/galloborates RbMT 3 (BO 3 ) 2 O 3 (M = Ba, Sr; T = Al, Ga) were synthesized for the first time using the high-temperature solution method. All the title compounds have Sr 2 Be 2 B 2 O 7 -like structures, in which the [BO 3 ] triangles and [TO 4 ] tetrahedra form the final double-layered configurations the M and Rb site atoms located between and in the double-layer, respectively. The structure evolution from Sr 2 Be 2 B 2 O 7 to RbMT 3 (BO 3 ) 2 O 3 series was discussed. The broaden energy bandgaps in Al-based borates when compared with Ga-based borates can be entirely attributed to the location of Al/Ga s orbitals near the Fermi surface. Further, both experimental and computational approaches were performed to study their structure-property relationship.

More than 3900 crystalline borates, including borate minerals and synthetic inorganic borates, in addition to a wealth of industrially-important boron-containing glasses, have been discovered and characterized. Of these compounds, 99.9 % contain only the traditional triangular BO3 and tetrahedral BO4 units, which polymerize into superstructural motifs. Herein, a mixed metal K5Ba2(B10O17)2(BO2) with linear BO2 structural units was obtained, pushing the boundaries of structural diversity and providing a direct strategy toward the maximum thresholds of birefringence for optical materials design. 11B solid-state nuclear magnetic resonance (NMR) is a ubiquitous tool in the study of glasses and optical materials; here, density functional theory-based NMR crystallography guided the direct characterization of BO2 structural units. The full anisotropic shift and quadrupolar tensors of linear BO2 were extracted from K5Ba2(B10O17)2(BO2) containing BO2, BO3, and BO4 and serve as guides to the identification of this powerful moiety in future and, potentially, previously-characterized borate minerals, ceramics, and glasses.

Three new tellurates, namely, K2BaPb0.62Ba0.38Te2O9 (1), Rb2BaPb0.7Ba0.3Te2O9 (2), and Ba2KLiTe2O9 (3), with hexagonal triple-perovskite structures have been designed via a cation substitution strategy. All three centrosymmetric compounds crystallize in the same hexagonal space group P63/mmc. In their structures, the [BTe2O9] (B = Pb/Ba for 1 and 2 and Li for 3) groups construct the final three-dimensional framework using face-sharing [Te2O9] dimmers and vertex-linked [BO6] linkages. Meanwhile, the theoretical calculations demonstrate the numerical differences of their birefringence. Thermal stability analysis and differential scanning calorimetry were performed, and UV-vis-NIR diffuse reflectance spectra and infrared spectra of the three title compounds were also characterized and analyzed.

Deep-ultraviolet nonlinear optical (DUV NLO) materials are attracting increasing attention because of their structural diversity and complexity. Using the two-dimensional (2D) crystal structure prediction method combined with the first-principles calculations, here we propose layered 18-membered-ring (18MR) boron oxide B2O3 polymorphs as high-performance NLO materials. 18MR-B2O3 with the AA and AB stackings are potential DUV NLO materials. The superior performing 18MR-B2O3AB has an unprecedentedly high second harmonic generation coefficient of 1.63 pm V-1, the largest among the DUV NLO materials, three times larger than that of the advanced DUV NLO material KBe2BO3F2 and comparable to that of beta-BaB2O4. Its unusually large birefringence of 0.196 at 400 nm guarantees the phase-matching wavelength lambda(PM) to reach this material's extreme absorption edge of approximate to 154 nm.

Four Na-based ternary infrared nonlinear-optical (IR NLO) materials, Na 6 MQ 4 (M = Zn, Cd, Q = S, Se), were prepared via high temperature flux method. The crystal structure of the compounds is built up of isolated [MQ 4 ]-tetrahedra and a three-dimensional (3D) framework formed by the NaQ n (n = 4, 5) units. The two selenides, Na 6 MSe 4 (M = Zn, Cd), as promising IR NLO materials, show moderate second-harmonic generation responses (0.9 and 0.5 × AgGaS 2 ) with good phase-matching behaviors, as well as high laser damage thresholds (2 and 1.9 × AgGaS 2 ).The two sulfides, Na 6 MS 4 (M =Zn, Cd), exhibit higher laser damage thresholds (13 and 4 × AgGaS 2 ) but smaller SHG responses (0.3 and 0.2 × AgGaS 2 ). The theoretical calculations and statistical analyses indicate that t he SHG effect and band gap in the compounds originate mainly from the distorted NaQ 4 NLO-active units, which provides a new insight into the design of novel IR NLO materials.

Looking for ultraviolet (UV) crystals with large birefringence that are easy to grow, and nontoxic, has always been a hotspot in the field of optical materials. Thus, finding novel chromophores and...

Fluorine-containing compounds significantly enrich the diversity of inorganic chemical structures. Here, four alkaline-earth metal difluorophosphates with different space groups, namely NH4Mg(PO2F2)3 (Cmcm) (1), NH4Sr(PO2F2)3 (P1[combining macron]) (2), (NH4)2Ba(PO2F2)4 (P2/n) (3) and Ba(PO2F2)2 (I4[combining macron]2d) (4), were synthesized and their structures were determined for the first time. 4 is not only the first alkaline-earth-metal difluorophosphate, but also the first difluorophosphate reported to crystallize in the non-centrosymmetric space group I4[combining macron]2d of the tetragonal crystal system. All of the three-dimensional (3D) structures of the title compounds consist of isolated (PO2F2)-, AE-O and NH4+ units, while the differences of the cation radius result in various arrangements of the (PO2F2)- units, which leads to diverse crystal structures and the disparate optical anisotropy of the crystals. According to the deep-ultraviolet (DUV) transmittance spectrum, 3 exhibits a short DUV cut off edge (

A new compound, namely (NH4)3PbCl5, has been synthesized via a low-temperature molten salt method in a closed system. It crystallizes in the orthorhombic Pnma (No. 62) space group. The crystal structure of (NH4)3PbCl5 features a distinct three-dimensional network constructed via hydrogen bonds that exist between ammonium and chloride anions. The UV-Vis-NIR diffuse reflectance spectrum displays a short UV cutoff edge at about 256 nm. Besides, the thermal behavior (TG and DSC) was also analyzed. To better understand the structure–property relationships of (NH4)3PbCl5, theoretical calculations based on density functional theory were also performed. The result shows that the birefringence is expected to be about 0.050 at 1064 nm, and the bandgap is about 4.45 eV, which is consistent with the experimental result.

The first borate featuring a three-dimensional B–O anionic network with edge-sharing (ES) [BO4] units, Pb2.28Ba1.72B10O19 (PbBaBO), has been synthesized under ambient pressure. The squeezing effect of the 2∞[B10O19] bilayer structure on the intra-layer co-edge [BO4] leads to an extremely long B–B distance and quite small internal O–B–O angles in the [B2O6] ring.

Owing to the tendency to form the glass state in growing crystals in the ternary tin(II) borate system, hitherto, very few single crystals in ternary tin(II) borate were reported. In this paper, a single crystal of Sn3B8O15 was obtained via a high temperature solution method in a closed system. The structure features a flexible fundamental building block [B8O18]12- constructed by one [BO3]3- unit and one [B7O16]11- group that contains three hexatomic rings, which further connect to compose a two-dimensional 2∞[B8O15] layer structure. The connection mode and flexibility of the three hexatomic B-O rings were analyzed, verifying the structural diversity of the B-O configuration. Moreover, the synthesis, crystal structure, and various characterizations were comprehensively presented. Also, theoretical calculations were employed to discuss structure-property relationships, and we use the real-space atom-cutting techniques to explain the origin of the birefringence of Sn3B8O15.

The simple binary fluoride α-SnF2 is shown to be an excellent birefringent material with outstanding birefringence, about 14 times that of MgF2 . Furthermore, it exhibits a shorter UV cutoff edge and easy crystal growth at ambient temperature compared to YVO4 and TiO2 . A novel theoretical calculation mode was established to analyze the stereochemical-activity lone-pair (SCALP) contribution to the birefringence (SCB) based on the SCALP's strength and arrangement, and it was found that the large birefringence of α-SnF2 mainly benefits from well-aligned [SnF5 ] polyhedra with a strong SCALP. The exploration of the α-SnF2 birefringent crystal points out the direction of the future search for excellent birefringent materials.

In contrast to the well-investigated halogen-containing borates and carbonates, very few halogen-containing borate carbonate compounds have been reported. Specifically, no example of borate carbonate fluoride has been synthesized successfully until now. Herein, the planar π-conjugated units [BO3 ]3- and [CO3 ]2- and the F- ions are introduced simultaneously into one crystal structure resulting in the first borate carbonate fluoride, Ba3 (BO3 )(CO3 )F, by the high-temperature solution method in the atmosphere. Its structure features a hexagonal channel formed by the [BO3 ]3- and [CO3 ]2- units with the [F3 Ba8 ]13+ trimers filled in the channel. Various characterizations including single crystal- and powder-XRD, EDX, IR, UV-vis-NIR, and TG-DSC, together with the first principles calculation have been carried out to verify the structure and fully understand the structure-property relationships.

Fluorooxoborates, as a newly found and promising deep-UV nonlinear optical (NLO) system, have exhibited superiority in optical performance. An in-depth study of the relationship among the symmetry,...

Plenty of nonlinear optical (NLO) crystals containing VO4 and AsO4 tetrahedra as NLO-active units have been found. Among them, Li3MO4 (M = V, As) and LiA2MO4 (A = Rb, Cs; M = V, As) are isostructur...

The zero-order waveplates, the essential materials in altering the polarization state of optical waves, are significant in polarimetry and the laser industry. Restricted by birefringence and absorp...

Advances in the generation of coherent lasers at wavelengths below 200 nm as well as the associated equipment and technologies have greatly spurred the development of nonlinear optical (NLO) materials that are capable of phase-matching in the deep-ultraviolet (deep-UV) spectral regions. However, few crystals can meet the technical demands, and studies to date have focused mainly on finding the next competitive candidates. Consequently, several crystals have emerged that hold great potential for the production of deep-UV harmonic coherent light, which benefit from newly developed systems with novel NLO-active units and chromophores. This Review provides a comprehensive overview of the developments of emergent candidates in the field of deep-UV NLO materials, discussing the recent efforts and active advances in the search for superior systems and in understanding their structure-property relationships. The intention is to provide a clear perspective on the current emergent deep-UV NLO candidates, and to accelerate the discovery of next candidates with high performances to meet the urgent demands.

By the selective fluorination of IO4 in iodates, SrI2O5F2 (SIOF) and Ba­(IO2F2)2 (BIOF) were synthesized successfully. They are the first reported cases of alkaline-earth metal fluoroiodates, and the (IO3F)2– units in SIOF were discovered for the first time to the best of our knowledge. BIOF possesses the shortest UV cutoff edge (230 nm), and SIOF has the largest birefringence (cal. 0.203 at 532 nm) among the reported fluoroiodates. The highly polarizable (IO3F)2–, with high polarizability anisotropy, induces a large birefringence in SIOF by theoretical calculation. This work will contribute to enlarge the structural diversity and provide a good choice for the material design in fluoroiodates.

A complex alkali and alkaline-earth metal borate Li4Ca2B8O16 has been synthesized successfully via the high-temperature solution method. Li4Ca2B8O16 crystallizes into the space group P1 (No. 2) of...

La3 B6 O13 (OH) was obtained by a high-pressure/high-temperature experiment at 6 GPa and 1673 K. The compound crystallizes in the space group P21 (no. 4) with the lattice parameters a=4.785(2), b=12.880(4), c=7.433(3) A, and β=90.36(10)°, and is built up of corner- as well as edge-sharing BO4 tetrahedra. It represents the first acentric high-pressure borate containing these B2 O6 entities. The compound develops borate layers of "sechser"-rings with the La3+ cations positioned between the layers. Single-crystal and powder X-ray diffraction, vibrational and MAS NMR spectroscopy, second-harmonic generation (SHG) and thermoanalytical measurements, as well as computational methods were used to affirm the proposed structure and the B2 O6 entities.

Sesquioxide crystals were identified as promising gain media for high-power ultrafast lasers, and the broadening of their fluorescence spectra could shorten the achievable laser pulses, correspondi...

Herein, a novel photonic coordination polymer material was constructed by aggregation-induced emission luminogen (AIEgen) containing a tripyridyl moiety used as the linking ligand. It displayed a spontaneous direct centrosymmetric to noncentrosymmetric phase transition in a single crystal. The two crystals, before and after the phase transition, were both controllably synthesized and characterized by single-crystal X-ray diffraction. After being exposed to air, the centrosymmetric metastable phase ( 1-α ) transitioned to a new stable phase with a noncentrosymmetric structure ( 1-β ). Interestingly, the 1-β structure exhibited a strong phase-matching second-harmonic generation (SHG) response, about 4.5 times higher than that of KH2PO4 (KDP). In order to better understand the relationship between the structure and the nonlinear optical properties, the dipole moments were calculated and discussed. Remarkably, the noncentrosymmetric phase with high thermal stability for 1-β retained and improved the initial photoluminescent properties of the AIEgen ligand after the structural phase transition from 1-α, and simultaneously produced the excellent SHG property, which are beneficial for the design and construction of excellent optical materials.

The exploration of novel infrared nonlinear optical (IR NLO) materials with large second-harmonic generation (SHG) responses and wide band gaps has become very imperative recently. Herein we report...

A new alkali metal iodate, K2Na(IO3)2(I3O8), has been synthesized using the mild hydrothermal method, which is the first example of noncentrosymmetric iodate containing isolated [IO3]− and [I3O8]− ...

Fluorooxoborates as potential deep ultraviolet (DUV) nonlinear optical (NLO) materials have exhibited diverse structures and NLO properties with metal cationic changes. Herein, the general mechanisms of metal cations on band gaps and optical properties in a series of typical fluorooxoborates have been clarified. It reveals that the framework of the emblematic 18-membered ring oxyfluorides has the flexibility of being able to contain different cations spanning from alkali to d10 metals by investigating the stability of the artificial CdB5 O7 F3 structure. Besides, introducing d10 metal cations can enhance the second harmonic generation (3.1×KH2 PO4 (KDP), d36 =0.39 pm V-1 ) and also keep a DUV spectral transparency (Eg >6.2 eV). Thus, the d10 -containing fluorooxoborate exhibits a great potential to be a new DUV optical material for nonlinear light-matter interactions.

The first zinc iodate fluoride, ZnIO3F, was synthesized by the Zn2+ cation, the IO3 group, and fluorine ion, where Zn2+ is coordinated by O atoms from iodate and F atoms to form the ZnO4F2 polyhedr...

The combination of the MoO6 octahedra and PO4 tetrahedra generates a new nonlinear optical crystal, KCsMoP2O9. To the best of our acknowledge, it exhibits the strongest powder second harmonic gener...

Stimulated Raman scattering processes based on Raman crystals offer a simple and effective method to generate mid-IR lasers. However, currently available mid-IR Raman crystals are extremely scarce. Herein, a new type of mid-IR Raman crystal, BaGeO3, is reported. It crystallizes in the monoclinic space group C2/c with Ba2+ cations and [Ge3O9]6- rings as basic building units and features high transparency from 2.5 to 5.5 μm and a Raman response larger than that of diamond. The BaGeO3 crystal has 45 IR-active modes (22Au + 23Bu) and 42 Raman-active modes (20Ag + 22Bg). The wide mid-IR transparent window is attributed to the low phonon energy of the second-order IR-active Au ⊗ Bg mode. The strongest Raman band, located at 799 cm-1, arises from the symmetrically stretching vibration of the [Ge3O9]6- extra-ring Ge-O bonds. The findings provide new insights into the crystallographic and Raman spectroscopic characteristics of high-performance mid-IR Raman crystals.

The alkali-metal molybdate iodate Na3(MoO4)(IO3) (I) and mixed-alkali-metal fluoromolybdate Na3Cs(MoO2F4)2 (II) were obtained via a mild hydrothermal reaction using a "Teflon-pouch" method. I crystallizes in the triclinic space group P1, whose structure comprises a 3D backbone made up of isolated [IO3]- pyramids and [MoO4]2- tetrahedra connected via 5- and 6-fold coordinated sodium cations. II crystallizes in the monoclinic space group P21/c and comprises isolated [MoO2F4]2- octahedra with strong out-of-center distortions and the Na+ as well as Cs+ cations acting as interstitial ions. Both compounds have been characterized by infrared (IR) spectra and ultraviolet-visible-near-infrared (UV-vis-NIR) diffuse reflectance spectra. First-principles calculations respectively reveal that they exhibit birefringence values with Δn = 0.078 and 0.210 at 1064 nm for I and II, and the origin of the birefringence is discussed.

Nonlinear optical materials are the vital components of future photonic technologies as they can transfer and process data at the speed of light. However, the necessary prerequisites for a practica...

Introducing Pb2+ cations with lone pair electrons in borates is efficient to form multiple crystalline forms. Here, we report two new compounds, α-Pb4B2O7 and β-Pb4B6O13, which exhibit different crystal forms from the previously reported lead borates, β-Pb4B2O7 and α-Pb4B6O13, respectively. Two sets of polymorphs: α-, β-Pb4B2O7 and α-, β-Pb4B6O13, exhibit completely different crystal structures and diverse optical properties. Thermal gravimetric and differential scanning calorimetry (TG-DSC) and variable-temperature powder X-ray diffraction (XRD) analyses were performed to study their thermodynamic stabilities. Structure-property relationships were discussed through first-principles calculation. Notably, the new phases, α-Pb4B2O7 and β-Pb4B6O13, have larger birefringence than their corresponding polymorphs due to the rearrangement of the functional groups in their structures.

Three new bismuth phosphates, Li2ABi(PO4)2 (A = K, Rb, and Cs), were synthesized through the high-temperature solution method. They all exhibit three-dimensional (3D) [Li2P2O8]4− frameworks built by isolated PO4 tetrahedra and Li–O chains but crystallize in two different space groups, which can be attributed to the effects of alkali metal cations that control the connection modes of units. Li2KBi(PO4)2, Li2RbBi(PO4)2 and Li2CsBi(PO4)2 show SHG intensities about 5.0, 3.1 and 2.5 times that of KDP, respectively, and are all phase-matchable. To the best of our knowledge, Li2KBi(PO4)2 exhibits the largest SHG response among the bismuth phosphates. The effects of cations on the SHG responses have been discussed in detail. Our results indicate that introduction of the Bi3+ cation with large distortion and synclastic arrangement of the Bi–O polyhedra is crucial to produce the large SHG response for phosphate NLO materials.

Crystals with both large birefringence and wide transparent range are suitable for broad applications in the areas of optical communications, the laser industry and modulation of the light polarization requirement. In this work, to assist the design of urgently needed crystals with large birefringence in the infrared (IR) region, typical alkali-metal chalcogenides, KPSe6, Na2Ge2Se5, and Li2In2GeSe6 have been studied. They exhibit a hierarchical characteristic in the calculated birefringence by about 0.21, 0.11, and 0.04, respectively. To explore the origin of the birefringence difference, the polarizability anisotropy and the effect of electron distribution anisotropy are analyzed. The alkali-metal chalcogenides KPSe6, Na2Ge2Se5, and Li2In2GeSe6 feature infinite one-dimensional (1D) chains of [PSe6], 2D anionic framework of [Ge2Se5] layers and 3D [In2GeSe9] networks, respectively. It is found that the anionic group with low-dimensional configuration could enhance polarizability anisotropy and render large birefringence for the macroscopic structure. This provides evidence that a low-dimensionality configuration in the structure would be beneficial for the enhancement of optical anisotropy, which can motivate the exploration and design of novel IR birefringent materials.

A noncentrosymmetric mixed alkali metal borate–bicarbonate, NaRb3B6O9(OH)3(HCO3), was synthesized and characterized. The compound crystallizes in the monoclinic space group P21 (No. 4) with a = 8.9...

The excellent birefringent materials are needed for optical systems. Herein, we reported a new compound, the first tin borate chloride, Sn2 B5 O9 Cl (SBOC) with a large birefringence (0.168 at 546 nm) measured by the polarizing microscope. Its birefringence is 16 times that of the isostructural Ba2 B5 O9 Cl (BBOC) compound (0.010@ at 546 nm). The results show that the birefringence enhancement originates mainly from the Sn2+ polyhedra. We propose that the birefringence can be enlarged by substituting the alkaline-earth metal cation by the Sn2+ cation in the isostructural borate with small birefringence. This strategy will guide the discovery of large birefringent materials in the future.

Exploration of new infrared (IR) nonlinear optical (NLO) materials is still in urgency owing to the indispensable roles in optoelectronic devices, resource exploration, and long-distance laser communication. The formidable challenge is to balance the contradiction between wide band gaps and large second harmonic generation (SHG) effects in IR NLO materials. In the present work, we proposed new kinds of NLO active units, d0 transition metal fluorooxo-functional groups for designing mid-IR NLO materials. By studying a series of d0 transition metal oxyfluorides (TMOFs), the influences of fluorooxo-functional groups with different d0 configuration cations on the band gap and SHG responses were explored. The results reveal that the fluorooxo-functional groups with different d0 configuration cations can enlarge band gaps in mid-IR NLO materials. The first-principles calculations demonstrate that the nine alkali/alkaline earth metals d0 TMOFs exhibit wide band gaps (all the band gaps > 3.0 eV), large birefringence Δn (> 0.07), and two W/Mo TMOFs also exhibit large SHG responses. Moreover, by comparing with other fluorooxo-functional groups, it is found that introducing fluorine into building units is an effective way to enhance optical performance. These d0 TMOFs with superior fluorooxo-functional groups represent a new exploration family of the mid-IR region, which sheds light on the design of mid-IR NLO materials possessing large band gap.

By using cation modulation strategy, a series of fluorooxoborates A3B3O3F6 (A = alkali and mixed alkali metal) were designed and successfully obtained via open high-temperature solid-state method for the first time, and single-crystal X-ray diffractions were used to determine their structures. The isolated B3O3F6 benzene-like ring structure in the title compounds is beneficial to obtain short ultraviolet absorption edge (

A series of metal chalcogenides, LiBa2MIIIQ4 (MIII = Al, Ga, In; Q = S, Se), have been successfully obtained by the sealed-tube method. LiBa2MIIIQ4 undergoes a special structural transformation fro...

The new oxychloride, Ba27Pb8O8Cl54, has been synthesized by a high temperature solution method. It crystallizes as cubic brown block with unit-cell a = 22.547(2), space group Fm 3 ¯ m (No. 225). It features a complicated three-dimensional network composed of [Ba20O4Cl92] and [Ba14O8Cl36] units sharing one Ba atom and its coordination atoms, which is inserted by new isolated [Pb4O4] clusters. The UV–Vis-IR diffuse reflectance spectrum exhibits that its optical band gap is about 3.9 eV. In this paper, the structural features, thermal behaviors and optical properties were systemically studied.

Two new A2Mg2TeB2O10 (A = Pb, Ba) compounds have been synthesized by the high temperature solution method. A2Mg2TeB2O10 (A = Pb, Ba) crystallize in the same space group Cmca and feature a 3D [B2TeMg2O10]4- framework structure. A2Mg2TeB2O10 (A = Pb, Ba) can be regarded as the cosubstitution of Na2RE2TeB2O10 (RE = Y, Dy-Lu), which crystallize in a different space group, P21/c. The discussion on the structure transformation from A2Mg2TeB2O10 (A = Pb, Ba) to Na2RE2TeB2O10 (RE = Y, Dy-Lu) indicates that the cosubstitution of two cations with different valence states can change the dimension of cation groups in the crystal structure, which can further alter the arrangements of the anion groups. Furthermore, the band gap and birefringence have been changed after the cosubstitution. The influences of the cosubstitution on the band gap and birefringence have been discussed through first-principles calculations and structure comparison. In addition, the IR spectra and TG-DSC curves of title compounds were studied.

Fluorooxoborates have inspired investigations of deep-ultraviolet (DUV) nonlinear optical (NLO) materials that can meet the multiple criteria. Herein, five stable structures with the composition of BaB2 O3 F2 (I-V) are discovered using the ab initio evolutionary algorithm. Among them, BaB2 O3 F2 -I has been synthesized experimentally and confirms the reliability of the method. All of the predicted structures possess extremely wide band gaps (8.1-9.0 eV). Moreover, four new structures exhibit giant second harmonic generation (SHG) coefficients (>3×KDP, d36 =0.39 pm V-1 ). A novel type of the [BOF] layer with BO3 :BO3 F ratio of [1:1] is found in BaB2 O3 F2 -II and BaB2 O3 F2 -III. While BaB2 O3 F2 -IV and BaB2 O3 F2 -V are solely composed of the BO3 F group and have colossal SHG coefficients (ca. 4×KDP). It gives the direct evidence that the BO3 F group could generate strong SHG effect. Most importantly, the influences of BO3 :BO3 F ratio and their number density on band gap, birefringence and SHG effects are investigated.

The first triple-layered borate with edge-sharing BO4 tetrahedra, β-CsB9 O14 was obtained under vacuum-sealed condition. It represents a new structure type and enriches the structural diversity of borates. Moreover, β-CsB9 O14 exhibits a short UV cutoff edge and a large birefringence, indicating that it could be regarded as a DUV birefringent crystal.

A new silicate fluoride, NaBa3Si2O7F, has been successfully synthesized by a high-temperature solution method. It crystallizes in the orthorhombic space group Cmcm (No. 63). NaBa3Si2O7F is the first barium-containing alkali metal silicate fluoride with the [NaO6] polyhedra, the [BaO8F] polyhedra and isolated [Si2O7] units. The optical characterizations indicate that NaBa3Si2O7F possesses wide transparent window and available luminescence properties. To confirm the coordination surroundings of anionic groups and its thermostability, infrared spectroscopy and thermal behaviors were also analyzed, which proved the existence of tetrahedronly coordinated silicium atoms and the good stability of NaBa3Si2O7F at high temperature. First-principles calculation was also implemented for better understanding the relationship between the structure of NaBa3Si2O7F and its property. Additionally, to further explore the structural novelty of NaBa3Si2O7F, the comparison of the anionic structures was carried out in mixed alkali and alkaline-earth metal silicate fluorides. Interestingly, the result indicates the isolated [Si2O7] dimer is rare among the above systems, which enriches the structural chemistry of silicate fluorides.

Efficient, high-power ultrafast lasers and their further chirped pulse amplification (CPA) are important for modern science, which requires the laser medium with high thermal conductivity, low phon...

Two barium-containing borates BaMBO4 (M = Al, Ga) were synthesized via the solid-state method under atmospheric pressure. The 3D configurations of BaGaBO4 and BaAlBO4 are comprised of ∞2[Ba4O16]24–...

Two phosphates, Cs2Zn5(PO4)(4) and Cs3La(PO4)(2) have been successfully synthesized by employing the conventional solid-state reaction method, and their structures were determined by single-crystal X-ray diffraction. Cs2Zn5(PO4)(4) owns a three-dimensional (3)(infinity)[Zn4P4O16] framework and Cs3La(PO4)(2) features (2)(infinity)[La3P6O29] layers spreading in the bc plane. Infrared spectroscopy, UV/Vis-NIR diffuse reflectance spectroscopy were performed. The thermal properties and electronic structures of two compounds were investigated. In addition, the Ce3+ doped Cs3La(PO4)(2) phosphor was synthesized and its photoluminescence was analyzed. The results indicate that the Cs2Zn5(PO4)(4):0.01Ce(3+) phosphor can be excited by ultraviolet light to obtain blue luminescence.

Four new deep ultraviolet (DUV) borates Li7Na2KRb2B12O24, Li7.35Na2.36K1.50Cs0.78B12O24, Li6.97Na2.63K1.24Cs1.15B12O24, and Li7.27Na2.67Rb2.06B12O24 have been produced by high temperature solution method in open air. The structural analysis suggests that they all crystallize in the same trigonal space group R 3 ¯ (No. 148), and possess the identical isolated B12O24 groups. Structural comparison among alkali-metal borates with BnO2n in their chemical formulas have been discussed. In addition, infrared spectra were used to verify their structural validity. Furthermore, the UV–Vis–NIR diffuse reflectance spectra reveal that they exhibit short cutoff edges below 180 nm (6.88 eV). The first-principles theoretical studies carried out to increase the understanding of electronic structure and linear optical property.

Two mixed halogen borate–carbonates K9[B4O5(OH)4]3(CO3)X·7H2O (X = Cl, Br) have been successfully synthesized with the hydrothermal method. They crystallize in the space group P62c, and their stru...

Substitution of oxygen by fluorine in the borate group offers a materials platform from which intriguing structure and functionality may arise. Herein, we report a new fluorooxoborate, BaB2 O3 F2 , synthesized by introducing the F atoms into the BaO-B2 O3 system. BaB2 O3 F2 exhibits a unique oxyfluoride layer 2∞ [B2 O3 F]- and a deep-ultraviolet cutoff edge below 180 nm. The effect of the introduction of F atoms on the structure and optical property of the borate group has been investigated; this should be useful to further expand borate chemistry and materials.