Be2BO3F: A Phase of Beryllium Fluoride Borate Derived from KBe2BO3F2 with Short UV Absorption Edge

Mg(C3 O4 H2 )(H2 O)2 : A New Ultraviolet Nonlinear Optical Material Derived from KBe2 BO3 F2 with High Performance and Excellent Water-Resistance

Acquiring high-performance ultraviolet (UV) nonlinear optical (NLO) materials that simultaneously exhibit a strong second harmonic generation (SHG) coefficients, as short as possible SHG phase-matching (PM) wavelength and non-hygroscopic properties has consistently posed a significant challenge. Herein, through multicomponent modification of KBe2 BO3 F2 (KBBF), an excellent UV NLO crystal, Mg(C3 O4 H2 )(H2 O)2 , was successfully synthesized in malonic system. This material possesses a unique 2D NLO-favorable electroneutral [Mg(C3 O4 H2 )3 (H2 O)2 ]∞ layer, resulting in the rare coexistence of a strong SHG response of 3×KDP (@1064 nm) and short PM wavelength of 200 nm. More importantly, it exhibits exceptional water resistance, which is rare among ionic organic NLO crystals. Theoretical calculations revealed that its excellent water-resistant may be originated from its small available cavity volumes, which is similar to the famous LiB3 O5 (LBO). Therefore, excellent NLO properties and stability against air and moisture indicate it should be a promising UV NLO crystal.

Ba3.75MgB7O14F2.5: A Mixed Alkaline-Earth Metal Borate Fluoride with Short Ultraviolet Cutoff Edge and Large Birefringence

Fluorine-containing borate crystal materials are particularly attractive due to their rich structural chemistry and excellent properties for optical applications. In this work, a new compound Ba3.75MgB7O14F2.5 has been synthesized through the high-temperature solution method. In the crystal structure of Ba3.75MgB7O14F2.5, the [B7O14] basic building unit and the [MgO3F3] octahedra are interconnected to create a complex three-dimensional network. The structural feature of the less commonly observed [B7O14] units is discussed, and it has been found that such units in Ba3.75MgB7O14F2.5 are most conducive to achieving large birefringence. In addition, Ba3.75MgB7O14F2.5 exhibits good thermal stability, a short ultraviolet cutoff of 203 nm, and large birefringence (0.081@546 nm), indicating its potential as a new UV birefringent crystal.

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].

Realization of Enlarged Birefringence from BaCdBe2(BO3)2F2 to NaMgBe2(BO3)2F via the Cation Size Effect as a Potential Deep-Ultraviolet Birefringent Material

Birefringence, as one of the most important factors for birefringent materials, governs their performances in applications. In this study, two previously unreported beryllium borates, BaCdBe₂(BO₃)₂F₂ (BDBBF) and NaMgBe₂(BO₃)₂F (NMBBF), have been rationally designed by modulating interstitial cations. When smaller sizes of the cations are used, the crystal structure of NMBBF exhibits closer-packed 2D [Be₆B₆O₁₂F₃]_∞ double layers rather than the 2D [Be₃B₃O₆F₃]_∞ single layers in the crystal structure of BDBBF. The ultraviolet (UV) transmittance spectrum indicates that the short UV absorption edges of BDBBF and NMBBF are below 200 nm. The results from both theoretical calculations (theo.) and experimental characterizations (exp.) reveal enlarged birefringence from BDBBF (0.067 at 589 nm from theo. and 0.059 at 546.1 nm from exp.) to NMBBF (0.078 at 589 nm from theo. and 0.081 at 546.1 nm from exp.). Because of its excellent structure-based optical properties, NMBBF has the potential to be a deep-UV birefringent material. Our structural comparison and discussion provide a scope to aid in the design of potential deep-UV birefringent materials with large birefringence.

Novel design for a polarizing DUV spectrometer using a Wollaston prism and its application as a diagnostic for measuring Thomson scattering data in the presence of strong self-emission backgrounds

We present a novel design for an optical spectrometer for use in ultraviolet Thomson scattering measurements of plasma parameters in high energy density (HED) inertial confinement fusion experiments on large-scale high-energy laser facilities. In experiments investigating high-Z plasmas, the fidelity of measurements is commonly limited by signal/background ratios approaching or exceeding unity. An alpha barium borate Wollaston prism can provide both spectral dispersion and polarization channel separation, allowing simultaneous measurement of both the Thomson scattering signal and plasma self-emission along a single line of sight and in a single experiment, which should greatly improve data quality and reduce the opportunity cost of taking high quality measurements. We present a basic discussion of the design and a worked example of an instrument designed to take fourth harmonic electron plasma wave measurements in HED experiments at the OMEGA laser facility.

Recent advances of oxyfluorides for nonlinear optical applications

Oxyfluorides exhibit rich crystal structures that provide a new perspective for designing new NLO materials.

Crystal Chemistry of High-Temperature Borates

In recent years borate-based crystals has attracted substantial interest among the research community. The overall importance of this family of materials is reflected in miscellaneous articles and several reviews that have been published over the years. Crystalline borate materials exhibit numerous interesting physical properties, which make them promising for further practical applications. Diversity of functional characteristics results from their high structural flexibility caused in the linkage of planar/non-planar BO₃ groups and BO₄ tetrahedra, which can occur as isolated or condensed structural units. This report is a brief review on crystal chemistry and structure features of anhydrous/high-temperature borates. Polymorphism of boron-oxygen radicals has been considered basing on cations' nature and synthesis conditions. Analysis of the laws governing borates structures and general principles of their systematics was discussed. As a result, an alternative classification of anhydrous compounds has been considered. It is based on four orders of their subdivision: (1) by the variety of anion formers, (2) by the cation charge, (3) by the N = N_M:N_B, i.e., ratio of metal atoms number to the ratio of boron atoms number (N-factor) value indicating the borate structural type (if it is known), (4) by the cation type and size.

Li3CaB2O5F: a unique sandwich-like structure with diverse and wide Li ion diffusion pathways

A new borate fluoride Li₃CaB₂O₅F has been synthesized.

Prediction of ternary fluorooxoborates with coplanar triangular units [BOxF3−x]x− from first-principles

From first-principles prediction, we got all the basic structural units of fluorooxoborates, namely, tetrahedral elements [BO_xF_4−x] (x = 1,2,3) like [BO₄] and triangular elements [BO_xF_3−x] (x = 1,2) like [BO₃].

Nontoxic KBBF Family Member Zn2BO3(OH): Balance between Beneficial Layered Structure and Layer Tendency

The conflict between beneficial layered structure for performances and layered growth habits in KBe2BO3F2 (KBBF) always restricts its practical applications. A beryllium-free KBBF family member, Zn2BO3(OH), is explored to feature the same topological layer with KBBF by replacing [BeO3F]5- with [ZnO3(OH)]5- and excellent UV performances. It exhibits a second harmonic generation response of about 1.5 × KH2PO4 with the UV cutoff edge of 204 nm. The birefringence of Zn2BO3(OH) in the visible region is about 0.067, which is larger than those of commercial UV crystals LiB3O5, CsB3O5, and CsLiB6O10. Additionally, it has excellent thermal and water-resistant stabilities. Owing to the removal of interlayer cations, Zn2BO3(OH) shows better growth habits than KBBF while achieving the balance between beneficial layered structure and layer tendency.

Rational Design and Synthesis of a Deep-Ultraviolet Nonlinear Optical Fluorinated Orthophosphate: BaZn(PO4)F

Rational design and tailored synthesis of noncentrosymmetric compounds with nonlinear optical (NLO) properties, especially in the deep-ultraviolet (deep-UV) region, remains a great challenge. Herein, we report on the development of a modified fluoro-solvo-hydrothermal method with two additive reagents (trimethylamine and NaF solution) as the solvents, using BaFe(PO₄)(OH) ( P2₁2₁2₁) as the prototype, for the rational design and tailored synthesis of the first deep-UV fluorinated orthophosphate, BaZn(PO₄)F. It crystallizes in the polar space group Pna2₁ and exhibits transparency down to deep-UV region (<190 nm) with SHG effect at 0.26 × KH₂(PO₄). Its structure is built from strictly alternating ZnO₄F trigonal bipyramids and PO₄ tetrahedra, resulting in a four-connected ABW-type zeolite framework. First-principles calculations confirm the deep-UV absorption edge and reveal that ZnO₄F plays an essential role in the NLO properties. The synergetic effect of Zn and F atoms leads to its more polar crystal structure, much deeper absorption edge, and better SHG effect than the prototype.

NH4 Be2 BO3 F2 and γ-Be2 BO3 F: Overcoming the Layering Habit in KBe2 BO3 F2 for the Next-Generation Deep-Ultraviolet Nonlinear Optical Materials

KBe₂ BO₃ F₂ (KBBF) is still the only practically usable crystal that can generate deep-ultraviolet (DUV) coherent light by direct second harmonic generation (SHG). However, applications are hindered by layering, leading to difficulty in the growth of thick crystals and compromised mechanical integrity. Despite efforts, it is still a great challenge to discover new nonlinear optical (NLO) materials that overcome the layering while keeping the DUV SHG available. Now, two new DUV NLO beryllium borates have been successfully designed and synthesized, NH₄ Be₂ BO₃ F₂ (ABBF) and γ-Be₂ BO₃ F (γ-BBF), which not only overcome the layering but also can be used as next-generation DUV NLO materials with the shortest type I phase-matching second-harmonic wavelength down to 173.9 nm and 146 nm, respectively. Significantly, γ-BBF is superior to KBBF in all metrics and would be the most outstanding DUV NLO crystal.

Toward a Slow-Release Borate Inhibitor To Control Mild Steel Corrosion in Simulated Recirculating Water

On the basis of their potential passivating characteristics, in this study, borates have been used to synthesize a novel slow-release inhibitor to suppress long-term mild steel corrosion in simulated recirculating water. The passivating performance was characterized by various electrochemical measurements and the passivating mechanism was interpreted by the point defect model. The experimental results indicated that the slow-release inhibitor exhibited a passivating efficiency of over 98% after 30 days of immersion, due to the formation of a passive film that was predominant by a Fe-O-B structure on the mild steel surface. This study provides a novel controlled-release concept and a slow-release borate inhibitor to control long-term corrosion.

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.

Structural Design of Two Fluorine-Beryllium Borates BaMBe2(BO3)2F2 (M = Mg, Ca) Containing Flexible Two-Dimensional [Be3B3O6F3]∞ Single Layers without Structural Instability Problems

Molecular structural design is a compelling strategy to develop new compounds and optimize the crystal structure by atomic-scale manipulation. Herein, two fluorine-beryllium borates, BaMgBe₂(BO₃)₂F₂ and BaCaBe₂(BO₃)₂F₂, have been rationally designed to overcome the structural instability problems of Sr₂Be₂B₂O₇ (SBBO). When relatively large Ba atoms were introduced, the [Be₆B₆O₁₅]_∞ double layers of SBBO were successfully broken, generating flexible [Be₃B₃O₆F₃]_∞ single layers. Also, the strategy adopted in this work has many implications in understanding the structural chemistry and designing novel optical functional materials in a beryllium borate system.

Li6Zn3(BO3)4: a new zincoborate featuring vertex-, edge- and face-sharing LiO4tetrahedra and exhibiting reversible phase transitions

A new zincoborate, Li₆Zn₃(BO₃)₄, was prepared, which exhibits two reversible phase transitions and contains a face-sharing LiO₄configuration.

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.