Borate Systems Research Articles

LiNa2Ca8B12O24F6Cl and Li1.2Na2.8B6O11: A Case of Cation-Induced Birefringence Enhancement via Dimensional Changes of Highly Polymerized [B12O24] Motifs.

Borates, due to their structural chemistry diversity and exceptional performance, are premier material systems for investigating UV optical crystals. The B-O anionic groups with high polymerization (B ≥ 6) are much less in the borate-based system, which is worthy of further research. Herein, cations with different radii and proportions are introduced to borate system, and two new highly polymerized borates, LiNa2Ca8B12O24F6Cl (LNCBFC) and Li1.2Na2.8B6O11 (LNBO) were designed and synthesized successfully. LNCBFC possesses commonly isolated high-symmetry [B12O24] groups, while the structure of LNBO contains an unprecedented 1∞[B12O22] chain constructed by [B12O24] groups. Owing to the orientation of the functional motifs in the chain structure, LNBO displays an enhanced birefringence, which is about 25 × higher than that of LNCBFC and retains a short UV cutoff edge (< 200 nm). Even more significantly, a discussion of the cationic modulation of [B12O24]-based compounds and the patterns of isolated [BnO2n] motifs consisting of B-O rings was carried out by reviewing previous studies and existing borates. This work puts forward a decent structure design and property regulation strategy for highly polymerized borates.

Theoretical Studies on γ-Photon/Neutron Shielding Characteristics of RE3+Co-Doped Borate, Phosphate, and Silicate Glass Systems

The Phy-X program software was used to investigate the γ- and neutron shielding properties of trivalent rare earth co-doped borate-, phosphate- and silicate glasses (G1-G10) concerning elemental composition and density. The attenuation coefficients (μ/ρ and μ), half/tenth value layer (HVL and TVL), and mean free path (MFP) were calculated, and each revealed the influence of rare earth including the Pb, Ba, and Bi elements. Energy and compositional dependent effective atomic number (Zeff), effective electron density (Neff), and effective electron conductivity (Ceff) of all the glasses were studied. On the high-density glasses G6, G9, and G10, the HVL and TVL values are projected to be lower than on the other examined glasses. The neutron radiation shielding abilities of the studied glasses were investigated by determining removal cross-section (RCS). The results were compared to those of commercially available materials such as concrete, graphite, water, and Hematite-serpentine concrete. The γ-ray exposure buildup and energy absorption factor values (EBF/EABF) of glass samples were determined in the energy range of 0.015 to 15 MeV.

Discovery of a new bimetallic borate with strong optical anisotropy activated by π-conjugated [B2O5] units.

Birefringent materials with high optical anisotropy have been identified as a research hotspot owing to their significant scientific and technological significance in modern optoelectronics for manipulating light polarization. Researchers studying borate systems have discovered that adding π-conjugated units placed in parallel can significantly increase the birefringence of crystalline solids; some examples include [BO3] units, [B2O5] units, and [B3O6] units. However, there are not many borates with strictly parallel configurations of π-conjugated [B2O5] units. In this study, a new bimetallic borate Sr2Cd4(B2O5)3 with near-parallel arrangement of π-conjugated [B2O5] units was discovered. Sr2Cd4(B2O5)3 possesses the maximum number density of [B2O5] units, shortest dihedral angle of [B2O5] units (between the two [BO3]), and largest degree of [CdO6] octahedral distortion among all the currently known Sr-Cd-B-O tetragonal system borates, making it demonstrate a large birefringence of 0.102 at 532 nm. Theoretical analysis proves that π-conjugated [B2O5] anions are the primary source of the large birefringence of Sr2Cd4(B2O5)3.

Activation parameters of viscous flow of guar gum and its cross-linked system

The structure of a cross-linked form of a concentrated solution of guar gum was studied using IR spectroscopy. The processes of viscous flow of concentrated solutions of guar gum and its cross-linked system have been studied. It is shown that this system is a non-Newtonian fluid with a thixotropic type of viscous flow anomaly, which is also determined by the nature of the complexing agent. The influence of temperature on viscous flow processes, as well as the structure of aqueous systems of guar gum and its cross-linked form, were studied based on the average statistical sizes of kinetic units, which makes it possible to estimate the mobility of structural elements and their sizes for concentrated systems. The activation parameters of the viscous flow of aqueous systems of guar gum and its cross-linked system were studied. Calculations of thermodynamic parameters were carried out free energy, heat of activation of viscous flow, characterizing the strength of structures, and entropy of activation of viscous flow, characterizing the ordering of structures. At high shear stresses, for the guar gum solution system, the processes of ordering and orientation prevail during flow, and for the guar gum - pentaerythritol borate system, the processes of structure destruction and disordering prevail.

Physical and radiation shielding properties for borate, boro-tellurite, and tellurite glass system modified with different modifiers: Comparative study

Two newly synthesized glass series, 10Bi2O3-20BaO-(70-x)B2O3-xTeO2, and 10MoO3-20SrO-(70-x)B2O3-xTeO2, where x = 0, 35, and 70 mol%, were fabricated using the melt-quenching technique. The fabricated glass samples' physical properties and radiation shielding capabilities were examined. The insertion of TeO2 into the glass composition increased the density values, with the glass samples labeled BBB-T70 (6.53 g/cm3) and SBM-T70 (5.66 g/cm3) exhibiting the highest density due to the increased concentration of TeO2. The addition of TeO2 led to loosely bonded glasses, indicating lower glass stability. Using SRIM and Phy-X/PSD software, the radiation shielding capabilities of the produced samples were investigated for various radiation types, including alpha particles, protons, neutrons, and gamma rays. The increase in TeO2 content and the reduction in B2O3 revealed significant increases in the linear attenuation coefficient (LAC) values and improved gamma shielding properties. For example, the LAC values at 0.283 MeV are 0.283, 0.367, 0.667, 0.902, 1.095, 1.313, and 1.55315 cm−1 for SBM-T00, SBM-T35, SBM-T70, BBB-T00, BBB-T53, and BBB-T70, respectively. However, the SBM-T00 sample exhibited lower charged particle shielding properties. The SBT-T35 and BBB-T00 samples showed the highest ability to stop fast neutrons. In conclusion, the glass samples synthesized in this work are highly recommended for shielding against various ionizing radiation sources.

Application of topological constraint theory to alkali borate and silicate glass systems

Principles of Topological Constraint Theory (TCT) were applied to alkali borate and silicate glass systems using intermediate range structural models over wide compositional ranges. The structural model for lithium borate was derived from the Feller, Dell, and Bray model [1] and extended to the terminal composition at R=3 where R is the molar ratio of lithium oxide to borate. The sodium borate structural model was built using both NMR [2] and Raman [3] data, and also included carbonate retention in the glass [4]. This model was extended to R=3 similarly to the lithium borate system. The silicate system models were created from 29Si NMR data [5] and also incorporated carbonate retention where necessary [6].Constraint models considered the effect of intermediate range structures on the system, and also incorporated the effect of “loose” alkali which is not directly associated with a non-bridging oxygen. Constraint models of the alkali borate, silicate, and borosilicate systems were then used to predict properties such as glass transition temperature and fragility.

A series of new rare-earth sulfide borates RE3S3BO3 (RE = Nd, Tb, Dy): Syntheses, structures and optical properties

Exploration of new compounds belonging to unusual families is always attractive for the everlasting development of material science. Here, three isomorphic rare-earth sulfide borates RE3S3BO3 (RE = Nd, Tb, Dy) have been obtained via a facile metal oxide-boron-sulfur solid-state routine. Their centrosymmetric triclinic structures feature 3D framework built by three types of REOxSy units, viz. REOS6, REO4S3, and REO3S6. Their structural relationship with similar phases and lanthanide contraction rule are discussed. Their optical band gaps are measured to be 2.59–2.70 eV, and the corresponding theoretical calculations are also performed. This work enriches the rarely studied chalcogenide borate system and is conducive to discovering more inorganic materials.

Target-Oriented Synthesis of Borate Derivatives Featuring Isolated [B3O3] Six-Membered Rings as Structural Features.

Borates provide an excellent platform for investigating the optical nonlinearity and linearity of crystals as photoelectric functional materials. In our work, borate derivatives with isolated [B3O3] six-membered rings as structural features are the preferred system due to their simple functional units and excellent properties. Herein, by utilizing the target-oriented synthesis, a series of borate derivatives, A2[B3O3F4(OH)] (A= NH4, Rb, Cs) (ABOFH), K2.3Cs0.7B3O3F6 (KCsBOF), and Cs3[B3O3(OH)3]Cl3 (CsBOHCl), with novel heteroanionic groups containing [BOxF4-x] (x = 0-3) and/or [BO2(OH)] units were obtained. ABOFH, KCsBOF, and CsBOHCl construct different two-dimensional pesudolayers featuring [B3O3F4(OH)], [B3O3F6], and [B3O3(OH)3] units, respectively. Also, the optical properties and the arrangement information of these anionic groups were studied. Among the total five compounds, (NH4)2[B3O3F4(OH)] and Cs3[B3O3(OH)3]Cl3 with enlarged birefringence and sufficient band gaps were screened out as promising birefringent crystals due to the optimally aligned configuration of birefringence-active heteroanionic units. The successful results of target-oriented synthesis indicate a more profound conclusion that the borate system now has more diversified structural chemistry, and an effective strategy was proposed to modify the arrangement and species of anionic units to optimize the performance of optical crystals.

КРИСТАЛЛИЗАЦИЯ СТЕКОЛ В РАЗРЕЗЕ Nа2O·2B2O3 — BaO·2B2O3 НАТРИЕВО-БАРИЕВО-БОРАТНОЙ СИСТЕМЫ

The results of crystallization of glass powders of the diborate section of the Na2O BaO B2O3 system are presented. The glass transition temperatures and temperature regions of crystallization at a heating rate of 10 K/min were determined by DTA and XRD methods; the formed crystalline phases were identified, and the nature and temperatures of their melting were established. It is shown that the section under study is not a pseudobinary system, but only a partial section of the sodium-barium borate system. It is shown that the Na2O·2BaO·9B2O3 compound is the phase of primary crystallization in the section; its field covers the majority of the section. The second known ternary compound, Na2O·2BaO·5B2O3, apparently melts peritectically. It has been established that during long-term heat treatment of glasses in a monolithic state, a new phase is formed in them with an approximate composition of Na2O·2BaO·6B2O3.

Gamma-ray-induced changes in the radiation shielding, structural, mechanical, and optical properties of borate, tellurite, and borotellurite glass systems modified with barium and bismuth oxide

This study explores the impact of different gamma-ray doses (2.5, 50, and 100 kGy) and TeO2 ratios on the structural, optical, mechanical, and radiation-shielding properties of borate glass systems modified with barium and bismuth oxide. Various physicochemical instruments were utilized to investigate these properties. The samples’ colors changed for all glasses with gamma-ray irradiation, and the color became more darkened with increasing doses. The Fourier transform infrared (FTIR) and Raman results confirmed the glass structure stability with different doses, but they offer a variation in intensity compatible with the bandgap energy results. Borate glass has the highest mechanical properties compared to the tellurite and borotellurite glass systems. Concomitantly, a gamma dose of up to 2.5 kGy enhanced the mechanical properties of all glass systems and then showed a reduction. Moreover, borate glass has the highest thermal stability compared to the tellurite and borotellurite glass, and gamma doses showed a slight variation. The tellurite and borate glasses recorded the highest and lowest band gaps, respectively. Experiments on the radiation-shielding properties and the effect of gamma doses were performed. The gamma-ray doses affected the mass attenuation coefficient (MAC) values of the tellurite and borotellurite glass samples. In contrast, the borate glass samples exhibited the highest MAC withstanding against gamma doses, and MAC values showed no variation with changing gamma doses. In summary, borate glass has the highest thermal stability, structural and mechanical properties, and stability in radiation-shielding features, which shows promise as an alternative for use in the radiation-shielding field.

Tailoring Variations in the Microstructures, Linear/Nonlinear Optical, and Mechanical Properties of Dysprosium-Oxide-Reinforced Borate Glasses

Hybrid dysprosium-doped borate glassy samples [B-Gly/Dy]HDG (Borate Glass/Dysprosium)Hybrid Doped Glass were prepared in this study via the melt-quenching method. Its linear/nonlinear optical, photoluminescence, hardness indentation, and micro-creep properties were analyzed. The amorphous structure for all the prepared samples was confirmed from the XRD patterns. In addition, density functional theory (DFT), optimized by TD-DFT and Crystal Sleuth, was used to study the structure and crystallinity of the [B-Gly/Dy]HDG as isolated molecules and agreed with the peaks of experimental XRD patterns. Additionally, theoretical lattice types were studied using Polymorph, a content studio software, and orthorhombic Pc21b (29) and triclinic P-1 (2) structures were provided. Both mechanical and optical properties were responses to different concentrations of Dy2O3 in the glassy borate system. It was found that the length of indentation increases by increasing the load time, and the hardness decreases by increasing the load time. The stress exponent value also increased from 4.1 to 6.3. The indentation strain increases by increasing the load time. The direct optical band gap was evaluated using the Davis–Mott relation. Urbach energy and its connection to the disorder degree in materials were studied depending on the Dy2O3 concentration. The acquired optical parameters were also analyzed to determine the nonlinear refractive index as well as the linear and third-order nonlinear optical susceptibility of the investigated glass samples. The photoluminescence emission spectra were recorded, and their attributed transitions were studied. The mechanical studies showed that the hardness values increased by increasing Dy2O3 concentrations from 4160.54 to 5631.58 Mpa. The stress exponent value also increased from 4.1 to 6.3. Therefore, the higher value of stress exponent (S) is more resistant to indentation creep.

Rational Design of the First Ammonium Magnesium Borate with Deep-Ultraviolet Cutoff Edge and Moderate Birefringence and Further Investigation into the Nature of Ammonium in the Borate System.

Through the rational design of the experimental method, the first combination of ammonium and magnesium in the borate system was successfully achieved. In this paper, a case of ammonium magnesium borate, (NH4)2{Mg(H2O)2[B6O7(OH)6]2}·2H2O, was successfully synthesized by a mild hydrothermal method at a relatively low temperature. A brief review was performed to show the participation of NH4+ in the recent development of optical materials. By discussing the optimum synthesis method of ammonium-containing borates and the main factors affecting the dimensionality of B-O anionic groups in their structures, the design strategy for synthesizing ammonium-containing borate and adjusting its structure has been put forward. Relevant experimental measurement results and the first-principles calculation results show that the title compound has a deep-UV cutoff edge (<200 nm) and moderate birefringence (Δncal. = 0.064 @546 nm), which indicates its potential application in the deep-UV region.

LiCs3AlB7O14: achieving enhanced optical anisotropy via [AlO4] tetrahedron introduction to rearrange the anionic framework.

Borate has become a hot topic because of its rich structural chemistry and excellent properties for functional materials fields. The rearrangement of π-conjugated B-O units is key to enhancing the optical anisotropy, but it remains a challenge. Herein, by introducing [AlO4] tetrahedra, a new congruent melting aluminoborate LiCs3AlB7O14 with [B7O14] clusters was discovered. This work confirms that the introduction of [AlO4] tetrahedra can lead to the rearrangement of anionic framework of the borate system and thereby enhance the birefringence of LiCs3AlB7O14. The birefringence is about 4.1 times higher than that of its congener Li4Cs3B7O14 with the same [B7O14] clusters. Similarly, the effects of [AlO4] tetrahedra on the rearrangement of the B-O anionic framework are also demonstrated in other known borates.

Li2PbB2O5: A Pyroborate with Large Birefringence Induced by the Synergistic Effect of Stereochemical Active Lone Pair Cations and π-Conjugated [B2O5] Groups.

Through the inclusion of two kinds of birefringence reactive groups, that is, Pb2+ cations with stereochemically active lone pairs and π-conjugated [B2O5] groups, a new pyroborate Li2PbB2O5 used to be acquired by the usage of the high-temperature solution method. The three-dimensional structural framework of Li2PbB2O5 is made up of highly distorted [PbO5] polyhedra and parallelly arranged π-conjugated [B2O5] groups via the connection of four- and five-coordinated Li+ cations. The birefringence of Li2PbB2O5 is 0.091 at 1064 nm, which is relatively large and revealed by the first-principles calculations. The contribution from the synergistic effect of the two kinds of birefringence reactive groups was substantiated via the analysis of the real-space atom cutting method. Also, the diffuse reflectance spectrum suggests that Li2PbB2O5 features a band gap of 4.0 eV, which corresponds to an ultraviolet (UV) cutoff edge. We hope that this work will foster further improvements in the design of UV birefringent crystal materials in the borate system.

Colorless SnO- and Sb2O3-containing borate and borosilicate glasses with small photoelastic and high refractive properties

We examined the relationship between optical properties and structures of 5s2-type cations such as Sn2+- and Sb3+-containing borate and borosilicate glass. Linear evolutions were observed for the compositional dependences of density, glass transition temperature, refractive index, and photoelastic constant in visible transparent oxide glasses. The structural information was provided using vibrational spectroscopy to elucidate polyhedral units of the borate and borosilicate systems. A weak ligand field around a Sn2+ close to tetrahedral borate unit, which is supported by applying density functional theory calculation, might lead to a blueshift of optical bandgap keeping small photoelastic constant and high refractive index.

Borates as a new direction in the design of oxide ion conductors

Lowering the operating temperature of solid oxide fuel cells (SOFCs) has extensively stimulated the development of new oxide ion conductors. Here, inspired by the structural commonalities of oxide ion conductors, the inability to accommodate oxygen vacancies in the rigid, isolated, 3-fold tetrahedral rings of SrSi/GeO3-based materials, and the considerable flexibility of BOn polyhedra in terms of coordination number, rotation, deformation, and linkage, we report the first borate-base family of oxide ion conductors, (Gd/Y)1−xZnxBO3−0.5x, through combined computational prediction and experimental verification. The oxygen vacancies in (Gd/Y)BO3 can be accommodated by forming B3O8 units in isolated, 3-fold, tetrahedral rings of B3O9 and transported through a cooperative mechanism of oxygen exchange between the B3O9 and B3O8 units, which is assisted by the intermediate opening and extending of these units. This study opens a new scientific field of the borate system for designing and discovering oxide ion conductors.

Radiation Shielding Parameters for Zinc Borate and Zinc Silicate Glasses Doped with Oxides of Bismuth -A Comparative Study

In the present work borate and silicate glass systems containing oxides of zinc and bismuth are explored as potential candidates for the radiation shielding applications. NIST XCOM computer program is employed for the estimations of mass attenuation and half value layer at different photon energy values ranging from 10-3MeV to 105 MeV. To get the idea regarding thickness of the glass material required to decrease the intensity of gamma ray photons to 50% of its starting value, the values of half value layer are analysed. Physical parameters like molar volume and density measurements are conducted to get insight of glass structure. The results obtained are compared with conventional shielding materials like concretes. The present work shows that the reports glasses in the present study are quite useful for radiation shielding purpose.

Ba2Zn2B6O13: coplanar [B2O5] in unnoted U-shaped [B6O13] groups achieving large birefringence.

Currently, π-conjugated [B2O5] moieties are rarely studied for designing deep-UV birefringent crystals. Here, we report a new deep-UV birefringent crystal Ba2Zn2B6O13 with a deep-UV cut-off edge of 190 nm and large birefringence (Δn = 0.085@ 532 nm), indicating that it can be used as the birefringent material in the DUV area. The first-principles calculation analyses suggest that its large birefringence mainly originates from the coplanar [B2O5] dimers in the unnoted U-shaped [B6O13].

Ba2B13O19(OH)5·5H2O: A promising nonlinear optical material with a unique 2[B13O19(OH)5]∞ two-dimensional layer

A case of hydrous borate with the formula of Ba2B13O19(OH)5·5H2O was synthesized by the traditional hydrothermal method. It crystallizes in the chiral P1 space group and has a unique two-dimensional 2[B13O19(OH)5]∞ layer that is constructed by the hydrogen involved [B13O22(OH)5] fundamental building blocks (FBBs). The Ba atoms and H2O molecules are filled in the three-dimensional pore constructed by the 2[B13O19(OH)5]∞ layer. Interestingly, Ba2B13O19(OH)5·5H2O is the first case of hydrous borates that has the above rare [B13O22(OH)5] FBB and 2[B13O19(OH)5]∞ layer, which enriching the structural chemistry of borate system. The diffuse reflection spectrum result shows that the ultraviolet (UV) cutoff edge of Ba2B13O19(OH)5·5H2O is below 200 nm. Its second harmonic generation (SHG) response is approximately 1.0 times that of potassium dihydrogen phosphate at the 1064 nm fundamental wavelength and it is also phase-matchable. Both results indicate that the title compound is a nonlinear optical crystal for UV spectral region. Theoretical simulation calculation shows that the occupied VE states are mainly contributed by the O-2p orbitals, and therefore [B13O22(OH)5] groups are the main sources of SHG effects.

A 4-hydroxyproline/trimethyl borate system for asymmetric synthesis of triple aldols from double aldol cyclic hemiacetals

We developed a 4-hydroxyproline-catalyzed asymmetric cross-aldol reaction between aldehydes and cyclic hemiacetals derived from copper-catalyzed asymmetric double aldol reaction reported previously by our group. The addition of trimethyl borate, which acted as a ring-opening reagent for hemiacetals, was critical for producing triple aldol compounds with excellent diastereoselectivity.