Guanylated borofluoride compounds, methods of making and using the same

Abstract

The disclosure provides a fluorinated guanidinium borate compound and a preparation method and application thereof, and belongs to the technical field of crystal materials and the technical field of optics. The chemical formula of the fluorinated guanidinium borate compound is (C(NH2)3)2B2OF6.

Description

Technical Field

[0001] This disclosure relates to the fields of crystal materials technology and optical technology, and in particular to a guanidine fluoride borate compound, its preparation method and application. Background Technology

[0002] Second-order nonlinear optical crystals are an important class of novel optoelectronic functional materials with significant application value in laser frequency conversion, laser intensity and phase modulation, optoelectronic communication, and optical information processing. With the development of laser technology and the emergence of tunable lasers, nonlinear optical devices have developed rapidly, including laser frequency doubling, mixing, parametric oscillation and amplification; electro-optic modulation, deflection, Q-switching, and photorefractive devices. With the strong demand for deep ultraviolet laser sources (generally referring to wavelengths shorter than 200 nm) from modern instruments such as 193nm photolithography, micro-nano precision laser processing, thorium-229 nuclear clocks, and ultra-high energy resolution photoelectron spectrometers and photoelectron emission microscopes, the development of all-solid-state deep ultraviolet laser sources has become a research hotspot. Deep ultraviolet nonlinear optical crystals are a crucial core component for the development of all-solid-state deep ultraviolet laser sources.

[0003] In related technologies, ultraviolet and deep ultraviolet nonlinear optical crystals mainly include LiB3O5 (LBO), CsB3O5 (CBO), and CsLiB6O. 10 LBO (Clear-Cooled Bone) crystals, BaB₂O₄ (BBO), KBa₂BO₃F₂ (KBBF), and KH₂PO₄ (KDP) crystals are used. LBO crystals, due to their relatively small nonlinear optics (Δn = 0.04 - 0.05), cannot achieve phase matching in the deep ultraviolet region, with a shortest harmonic wavelength of 276 nm. Similarly, CBO and CLBO crystals, like LBO, are limited in their applications in the deep ultraviolet region due to their relatively small nonlinear optics. While BBO crystals possess large harmonic coefficients and nonlinear optics, their relatively high ultraviolet absorption cutoff edge (189 nm) and shortest harmonic wavelength of 204.8 nm limit their applications in the deep ultraviolet region. KBBF can achieve direct sixth-harmonic output of 1064 nm fundamental frequency light, but its layered growth habit makes large-size crystal growth difficult, limiting its applications to some extent. KDP crystals currently have a transmittance range of 0.18–1.7 μm and are mainly used in the visible light band. Therefore, there is an urgent need to develop new deep ultraviolet nonlinear optical crystals with excellent comprehensive performance. Summary of the Invention

[0004] In view of this, the present disclosure provides a guanidine fluoride borate compound, its preparation method and application.

[0005] According to one aspect of the present disclosure, a guanidine fluoride borate compound is provided, the chemical formula of which is (C(NH2)3)2B2OF6.

[0006] According to embodiments of this disclosure, the aforementioned guanidine fluoride borate compound has a nonlinear optical crystal structure belonging to the monoclinic crystal system, including crystal form I and / or crystal form II; wherein, the space group of crystal form I is Cc, and the cell parameters are a = 12.58 ± 0.02 Å, b = 7.34 ± 0.02 Å, c = 13.02 ± 0.02 Å, alpha = 90°, beta = 114.27 ± 0.02°, gamma = 90°, and Z = 1; the space group of crystal form II is Cm, and the cell parameters are a = 11.85 ± 0.02 Å, b = 7.21 ± 0.02 Å, c = 8.06 ± 0.02 Å, alpha = 90°, beta = 128.40 ± 0.02°, gamma = 90°, and Z = 2.

[0007] According to embodiments of this disclosure, the aforementioned guanidine fluoride borate compound includes crystal form I and / or crystal form II; crystal form I includes one or more diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ; crystal form II includes a diffraction peak at 19.1°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0008] According to embodiments of the present disclosure, the crystal form I further includes one or more diffraction peaks at 14.6°±0.2°, 15.4°±0.2°, 16.5°±0.2°, 24.5°±0.2°, 27.6°±0.2°, 29.3°±0.2°, and 30.1°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0009] According to embodiments of the present disclosure, the crystal form II further includes one or more diffraction peaks at 14.0°±0.2°, 15.5°±0.2°, 16.5°±0.2°, 24.7°±0.2°, 27.7°±0.2°, 30.5°±0.2°, and 31.4°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0010] According to another aspect of this disclosure, a method for preparing the above-mentioned guanidine fluoride borate compound is provided, comprising the following steps: reacting a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound to obtain the guanidine fluoride borate compound; wherein the guanidine-containing compound and the fluorine-containing compound may be the same or different.

[0011] According to embodiments of this disclosure, the reaction of a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound to obtain a guanidine fluoride borate compound comprises: mixing the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound with a first solvent to obtain a mixed solution; and reacting the mixed solution by a hydrothermal method, a solvent method, or an evaporation method to obtain the guanidine fluoride borate compound.

[0012] According to embodiments of this disclosure, the hydrothermal method includes: placing the above mixed solution in a sealed container, heating it to 160-230°C at a rate of 20-60°C / h, maintaining the temperature for 3-15 days, and then cooling it to room temperature at a rate of 2-10°C / h to obtain the above guanidine fluoride borate compound.

[0013] According to embodiments of this disclosure, the solvent method comprises: evaporating the first solvent in the mixed solution at room temperature to obtain the guanidine fluoride borate compound.

[0014] According to embodiments of this disclosure, the above-mentioned evaporation method includes: heating the above-mentioned mixed solution to 50-120°C at a rate of 5-10°C / h, evaporating the first solvent, and obtaining the above-mentioned guanidine fluoride borate compound.

[0015] According to embodiments of this disclosure, the compound with the C(NH2)3 group is one or more of C(NH2)3BF4, C(NH2)3F, C(NH2)3HF2, C(NH2)3CO3, and C(NH2)3Cl.

[0016] According to embodiments of this disclosure, the boron-containing compound is one or more of boric acid, boron oxide, and soluble borate.

[0017] According to embodiments of this disclosure, the fluorinated compound is one or more of C(NH2)3F, C(NH2)3HF2, HBF4, C(NH2)3BF4, or HF.

[0018] According to embodiments of this disclosure, the molar ratio of the above-mentioned guanidine-containing compound, the above-mentioned boron-containing compound, and the above-mentioned fluorine-containing compound is (0.5~2):(1~5):(0~4).

[0019] According to embodiments of this disclosure, in the above-described hydrothermal method, the first solvent is water.

[0020] According to embodiments of this disclosure, in the above-described solvent method, the first solvent is one or more of water, ethanol, hydrofluoric acid, or tetrafluoroboric acid.

[0021] According to embodiments of this disclosure, in the above-described evaporation method, the first solvent is water.

[0022] According to another embodiment of this disclosure, a crystal growth method is provided, comprising: growing a seed crystal using a flux method, a crucible lowering method, a room temperature solution method, or a solvothermal method to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20 mm. The seed crystal is a nonlinear optical crystal of the guanidine fluoride compound (C(NH2)3)2B2OF6, including crystal form I or crystal form II. Crystal form I has a space group of Cc, cell parameters a = 12.58 ± 0.02 Å, b = 7.34 ± 0.02 Å, c = 13.02 ± 0.02 Å, alpha = 90°, beta = 114.27 ± 0.02°, gamma = 90°, and Z = 1. Crystal form II has a space group of Cm, cell parameters a = 11.85 ± 0.02 Å, b = 7.21 ± 0.02 Å, c = 8.06±0.02 Å, alpha=90°, beta=128.40±0.02°, gamma=90°, Z = 2.

[0023] According to another aspect of this disclosure, the application of the guanidine fluoride borate compound or the guanidine fluoride borate nonlinear optical crystal grown by the crystal growth method described above is provided in optical frequency doubling, optical parametric amplification, and optical parametric oscillation.

[0024] According to embodiments of this disclosure, a guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6 can be used to prepare a nonlinear optical crystal. This nonlinear optical crystal exhibits a large frequency doubling coefficient and nonlinear optics, with an ultraviolet cutoff edge below 200 nm, demonstrating good overall performance. Furthermore, this nonlinear optical crystal also possesses a wide transmission band, stable physicochemical properties, high mechanical hardness, is not easily broken or deliquescent, and is easy to cut, polish, and store.

[0025] The preparation method of the guanidine fluoride borate compound provided in this disclosure is simple and low in cost.

[0026] The method for preparing guanidine fluoride borate compounds provided in this disclosure can obtain crystal form I and / or crystal form II with a size on the order of centimeters, and without obvious layered growth habit; and by using a large crucible or container and extending the crystal growth period, a correspondingly large nonlinear optical crystal can be obtained. In the growth of this nonlinear optical crystal, the crystal is easy to grow, transparent, and without encapsulation, and has the advantages of fast growth rate, low cost, and easy acquisition of large-size crystals.

[0027] According to the embodiments of this disclosure, a large-size nonlinear optical crystal provided in the embodiments of this disclosure can be used. Based on the crystallographic data of the crystal, the crystal blank is oriented, the crystal is cut according to the required angle, thickness and cross-sectional size, and the light-transmitting surface of the crystal is polished. It can then be used as a nonlinear optical device. This nonlinear optical crystal has advantages such as a wide light transmission band, stable physical and chemical properties, high mechanical hardness, not easy to break or deliquesce, and easy to cut, polish and store. Attached Figure Description

[0028] Figure 1 A crystal structure diagram of crystal form I of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0029] Figure 2 A crystal structure diagram of crystal form II of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown;

[0030] Figure 3 The X-ray powder diffraction pattern of crystal form I of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0031] Figure 4 The X-ray powder diffraction pattern of crystal form II of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0032] Figure 5 The diagram shows the working principle of a nonlinear optical device fabricated from a nonlinear optical crystal according to an embodiment of the present disclosure, wherein 1 is a laser, 2 is a convex lens, 3 is a nonlinear optical crystal, 4 is a prism, and 5 is a filter. Detailed Implementation

[0033] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0035] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0036] In related technologies, ultraviolet and deep ultraviolet nonlinear optical crystals mainly include LiB3O5 (LBO), CsB3O5 (CBO), and CsLiB6O. 10 LBO (ClO2), BaB2O4 (BBO), and KBa2BO3F2 (KBBF) crystals. LBO crystals exhibit a wide transmission range, high optical uniformity, a large effective frequency doubling factor (3KDP), and a high damage threshold (18.9 GW / cm²). 2 However, due to its relatively small nonlinear optics (Δn = 0.04 - 0.05), it cannot achieve phase matching in the deep ultraviolet region, with a minimum harmonic doubling wavelength of 276 nm. Similar to LBO crystals, CBO and CLBO crystals are also limited in their application in the deep ultraviolet region due to their relatively small nonlinear optics. Although BBO crystals have a large harmonic doubling coefficient and nonlinear optics, their relatively high ultraviolet absorption cutoff edge (189 nm) results in a minimum harmonic doubling wavelength of 204.8 nm, thus limiting their application in the deep ultraviolet region. KBBF can achieve direct sixth-harmonic output of 1064 nm fundamental frequency light, but due to its layered growth habit, growing large-size crystals is difficult, which limits its application to some extent. Therefore, there is an urgent need to develop new deep ultraviolet nonlinear optical crystals with excellent comprehensive performance.

[0037] Deep ultraviolet (DUV) nonlinear optical crystals are crucial core components for the development of all-solid-state DUV laser sources (generally referring to wavelengths shorter than 200 nm). Currently, existing UV and DUV nonlinear optical crystals are insufficient to meet application requirements, necessitating the development of novel DUV nonlinear optical crystals with superior overall performance.

[0038] In the process of realizing this disclosure, it was discovered that guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6 can be used to prepare nonlinear optical crystals.

[0039] Specifically, according to one aspect of the present disclosure, a guanidine fluoride borate compound is provided, the chemical formula of which is (C(NH2)3)2B2OF6.

[0040] According to embodiments of this disclosure, the molecular weight of the guanidine fluoride borate compound is 271.77.

[0041] According to embodiments of this disclosure, a guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6 can be used to prepare a nonlinear optical crystal. This nonlinear optical crystal exhibits a large frequency doubling coefficient and nonlinear optics, with an ultraviolet cutoff edge below 200 nm, demonstrating good overall performance. Furthermore, this nonlinear optical crystal also possesses a wide transmission band, stable physicochemical properties, high mechanical hardness, is not easily broken or deliquescent, and is easy to cut, polish, and store.

[0042] According to embodiments of this disclosure, the guanidine fluoride borate compound has a nonlinear optical crystal structure belonging to the monoclinic crystal system, including crystal form I and / or crystal form II; wherein, crystal form I has a space group of Cc, and cell parameters of a = 12.58 ± 0.02 Å, b = 7.34 ± 0.02 Å, c = 13.02 ± 0.02 Å, alpha = 90°, beta = 114.27 ± 0.02°, gamma = 90°, and Z = 1; crystal form II has a space group of Cm, and cell parameters of a = 11.85 ± 0.02 Å, b = 7.21 ± 0.02 Å, c = 8.06 ± 0.02 Å, alpha = 90°, beta = 128.40 ± 0.02°, gamma = 90°, and Z = 2.

[0043] For example, the unit cell parameters of crystal form I are a = 12.586(3) Å, b = 7.346(2) Å, c = 13.023(3) Å, alpha = 90°, beta = 114.274(9)°, gamma = 90°, Z = 1, V = 1097.6(5) Å. 3 The unit cell parameters of crystal form II are a = 11.8550(17) Å, b = 7.2135(9) Å, c = 8.0657(10) Å, alpha = 90°, beta = 128.408(4)°, gamma = 90°, Z = 2, V = 540.49(12) Å. 3 .

[0044] Figure 1 A crystal structure diagram of crystal form I of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0045] Figure 2A crystal structure diagram of crystal form II of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0046] According to embodiments of this disclosure, the guanidine fluoride borate compound may include crystal form I or crystal form II, that is, the guanidine fluoride borate compound is a single crystal form, so as to achieve better application results.

[0047] According to embodiments of the present disclosure, the guanidine fluoride borate compound includes crystal form I and / or crystal form II; crystal form I includes one or more diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ; crystal form II includes a diffraction peak at 19.1°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0048] According to embodiments of the present disclosure, crystal form I may include a diffraction peak at one of the following locations in an X-ray powder diffraction pattern with a diffraction angle of 2θ: 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, or 32.5°±0.2°.

[0049] According to embodiments of this disclosure, crystal form I may include diffraction peaks at two of the following locations in an X-ray powder diffraction pattern with a diffraction angle of 2θ: 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2°. Exemplarily, crystal form I may include diffraction peaks at 17.6°±0.2° and 18.3°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ. Crystal form I may also include diffraction peaks at 22.9°±0.2° and 32.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0050] According to embodiments of this disclosure, crystal form I may include diffraction peaks at three of the following locations in an X-ray powder diffraction pattern with a diffraction angle of 2θ: 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2°. Exemplarily, crystal form I may include diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, and 22.9°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ. Crystal form I may also include diffraction peaks at 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0051] According to embodiments of the present disclosure, crystal form I may include diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0052] According to embodiments of the present disclosure, crystal form I also includes one or more diffraction peaks at 14.6°±0.2°, 15.4°±0.2°, 16.5°±0.2°, 24.5°±0.2°, 27.6°±0.2°, 29.3°±0.2°, and 30.1°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0053] For example, crystal form I includes diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 14.6°±0.2° and 15.4°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0054] Crystal form I exhibits diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, 32.5°±0.2°, 14.6°±0.2°, 15.4°±0.2°, 16.5°±0.2°, 24.5°±0.2°, 27.6°±0.2°, 29.3°±0.2°, and 30.1°±0.2° in its X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0055] According to embodiments of the present disclosure, crystal form II also includes one or more diffraction peaks at 14.0°±0.2°, 15.5°±0.2°, 16.5°±0.2°, 24.7°±0.2°, 27.7°±0.2°, 30.5°±0.2°, and 31.4°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0056] For example, crystal form II includes diffraction peaks at 19.1°±0.2° and 14.0°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ. Crystal form II also includes diffraction peaks at 19.1°±0.2° and 15.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ. Furthermore, crystal form II includes diffraction peaks at 19.1°±0.2°, 15.5°±0.2°, and 16.5°±0.2° in an X-ray powder diffraction pattern with a diffraction angle of 2θ. Crystal form II includes diffraction peaks at 19.1°±0.2°, 14.0°±0.2°, 15.5°±0.2°, 16.5°±0.2°, 24.7°±0.2°, 27.7°±0.2°, 30.5°±0.2°, and 31.4°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0057] According to embodiments of this disclosure, a crystal form refers to a crystal structure (or polymorph) having a specific molecular packing arrangement in a crystal lattice. Crystal forms can be identified and distinguished from each other using one or more characterization techniques, including, for example, X-ray powder diffraction (XRPD). In embodiments of this disclosure, the crystal form of the guanidine fluoride borate compound refers to a unique crystal form that can be identified and distinguished from each other using one or more characterization techniques, including, for example, X-ray powder diffraction (XRPD). According to embodiments of this disclosure, the X-ray powder diffraction pattern of the crystal form of the guanidine fluoride borate compound has one or more diffraction peaks at one or more specified 2θ diffraction angles.

[0058] According to embodiments of this disclosure, X-ray powder diffraction is a method for performing diffraction analysis on powdered polycrystalline samples using monochromatic X-rays. An X-ray powder diffraction pattern refers to an experimentally obtained spectrum plotted as signal position (x-axis) versus signal intensity (y-axis). For amorphous materials, an X-ray powder diffraction pattern may include one or more broad, flat diffraction peaks; for crystalline materials, an X-ray powder diffraction pattern may include one or more fine, tall, and sharp diffraction peaks, each identified by its angle value, measured as angle 2θ, plotted on the x-axis of the X-ray powder diffraction pattern.

[0059] According to embodiments of this disclosure, the repeatability of the measured angle value is within ±0.2°, that is, the angle value can be an angle value +0.2°, an angle value -0.2°, or any value between these two endpoints (angle value +0.2° and angle value -0.2°). Optionally, the repeatability of the measured angle value is within ±0.1°.

[0060] According to embodiments of this disclosure, the X-ray powder diffraction pattern of crystal form I is substantially as follows: Figure 3 As shown. Figure 3 The X-ray powder diffraction pattern of crystal form I of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0061] According to embodiments of this disclosure, the X-ray powder diffraction pattern of crystal form II is substantially as follows: Figure 4 As shown. Figure 4 The X-ray powder diffraction pattern of crystal form II of the guanidine fluoride borate compound provided in the embodiments of this disclosure is shown.

[0062] According to embodiments of this disclosure, "substantially" refers to the fact that the positions and intensities of diffraction peaks in an X-ray powder diffraction pattern can vary. For example, the position of the diffraction peaks (2θ) can exhibit some inter-device variability, typically up to 0.2°. Sometimes, the variability may be greater than 0.2° depending on differences in device calibration.

[0063] According to another aspect of this disclosure, a method for preparing the above-mentioned guanidine fluoride borate compound is provided, comprising the following steps: reacting a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound to obtain the guanidine fluoride borate compound; wherein the guanidine-containing compound and the fluorine-containing compound may be the same or different.

[0064] For example, when a guanidine-containing compound contains fluorine, the fluorine-containing compound can be the same substance as the guanidine-containing compound.

[0065] The preparation method of the guanidine fluoride borate compound provided in this disclosure is simple and low in cost.

[0066] According to embodiments of this disclosure, the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound is (0.5~2):(1~5):(0~4). Exemplarily, the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound can be 0.5:1:0.1, 0.5:2:3, 0.5:5:4, 1:2:3, 1:5:4, 2:1:1, 2:2, 2:3:3, 2:5:4, etc.

[0067] According to embodiments of this disclosure, reacting a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound to obtain a guanidine fluoride borate compound includes: mixing the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound with a first solvent to obtain a mixed solution; and reacting the mixed solution by a hydrothermal method, a solvent method, or an evaporation method to obtain the guanidine fluoride borate compound.

[0068] According to embodiments of this disclosure, the concentration of the guanidine-containing compound can be 2-6 mol / L. Exemplarily, the concentration of the guanidine-containing compound can be 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, etc. The concentration of the boron-containing compound can be 2-6 mol / L. Exemplarily, the concentration of the boron-containing compound can be 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, etc. The concentration of the fluorine-containing compound can be 0-6 mol / L. Exemplarily, the concentration of the fluorine-containing compound can be 0, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, etc.

[0069] The method for preparing guanidine fluoride borate compounds provided in this disclosure can obtain crystal form I and / or crystal form II with a size on the order of centimeters, and without obvious layered growth habit; and by using a large crucible or container and extending the crystal growth period, a correspondingly large nonlinear optical crystal can be obtained. In the growth of this nonlinear optical crystal, the crystal is easy to grow, transparent, and without encapsulation, and has the advantages of fast growth rate, low cost, and easy acquisition of large-size crystals.

[0070] According to embodiments of this disclosure, the hydrothermal method includes: placing the mixed solution in a sealed container, heating it to 160-230°C at a rate of 20-60°C / h, maintaining the temperature for 3-15 days, and then cooling it to room temperature at a rate of 2-10°C / h to obtain a guanidine fluoride borate compound.

[0071] According to embodiments of this disclosure, the hydrothermal preparation of guanidine fluoride borate compounds can be carried out in a high-pressure reactor with a capacity of 23 mL to 100 mL.

[0072] According to embodiments of this disclosure, in the hydrothermal method, the first solvent is water.

[0073] Specifically, the hydrothermal method may include: mixing a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound evenly, adding deionized water to fully mix and dissolve them to obtain a mixed solution; transferring the mixed solution into a clean, uncontaminated high-pressure reactor and sealing the reactor tightly; placing the high-pressure reactor in a constant temperature chamber, heating it to 160-230°C at a rate of 20-50°C / h, maintaining the temperature for 2-5 days, and then cooling it to room temperature at a rate of 2-10°C / h to obtain a guanidine fluoride borate compound, which includes crystal form I and / or crystal form II.

[0074] According to embodiments of this disclosure, the solvent method includes: evaporating a first solvent in a mixed solution at room temperature to obtain a guanidine fluoride borate compound.

[0075] According to embodiments of this disclosure, room temperature can be an indoor temperature, such as the temperature of a laboratory or factory where guanidine fluoride borate compounds are prepared. For example, room temperature can be 20~40°C.

[0076] According to embodiments of this disclosure, in the solvent method, the first solvent may be one or more of water, ethanol, hydrofluoric acid, or tetrafluoroboric acid.

[0077] Specifically, the solvent method may include: mixing a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound evenly, placing them in a polytetrafluoroethylene (PTFE) beaker, adding a first solvent to fully mix and dissolve them to obtain a mixed solution; sealing the container containing the mixed solution with a polyvinyl chloride (PVC) film, placing it in a static environment free from shaking, pollution, and air convection, punching several small holes in the seal to adjust the evaporation rate of the solvent in the solution, allowing it to stand at room temperature, and then gradually precipitating crystals in the solution. After the growth is complete, quickly washing the product in the PTFE beaker with deionized water, evaporating and crystallizing at room temperature to obtain a guanidine fluoride borate compound, which includes crystal form I and / or crystal form II.

[0078] According to embodiments of this disclosure, in the solvent method, the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound is preferably (0.5~2):(3~5):(0.5~2).

[0079] According to embodiments of this disclosure, the evaporation method includes: heating the mixed solution to 50-120°C at a rate of 5-10°C / h, evaporating the first solvent, and obtaining a guanidine fluoride borate compound.

[0080] According to embodiments of this disclosure, in the evaporation method, the first solvent is water.

[0081] Specifically, the evaporation method may include: mixing and grinding a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound evenly, then adding deionized water to fully mix and dissolve them to obtain a mixed solution; placing the mixed solution in a beaker, then subjecting it to ultrasonic treatment to ensure thorough mixing and dissolution, and filtering it with qualitative filter paper; placing the beaker containing the mixed solution in a constant temperature chamber, raising the temperature of the chamber to 50-120°C at a rate of 5-10°C / h, and maintaining the temperature for 3-15 days (standing) until growth is complete, thereby obtaining a guanidine fluoride borate compound, which includes crystal form I and / or crystal form II.

[0082] According to embodiments of this disclosure, in the evaporation method, the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound is preferably (0.5~2):(3~5):(0.5~2).

[0083] According to embodiments of this disclosure, the guanidine-containing compound is one or more of C(NH2)3BF4, C(NH2)3F, C(NH2)3HF2, C(NH2)3CO3, and C(NH2)3Cl.

[0084] According to embodiments of this disclosure, the boron-containing compound is one or more selected from boric acid, boron oxide, and soluble borate. Exemplarily, the boron-containing compound may be one or more selected from HBO2, H3BO3, B2O3, and K2B2O4·3H2O.

[0085] According to embodiments of this disclosure, the fluorinated compound is one or more of C(NH2)3F, C(NH2)3HF2, HBF4, C(NH2)3BF4, or HF.

[0086] According to another aspect of this disclosure, a crystal growth method is provided, comprising: growing a seed crystal using a flux method, a crucible lowering method, a room temperature solution method, or a solvothermal method to obtain a guanidine fluoride borate nonlinear optical crystal with a size of 1-20 mm (e.g., 1 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, etc.), wherein the seed crystal is a nonlinear optical crystal of a guanidine fluoride borate compound (C(NH2)3)2B2OF6, including crystal form I or crystal form II.

[0087] Crystal form I satisfies at least one of the following conditions:

[0088] (1) The space group of crystal form I is Cc, and the unit cell parameters are a = 12.58±0.02 Å, b = 7.34±0.02 Å, c = 13.02±0.02 Å, alpha = 90°, beta = 114.27±0.02°, gamma = 90°, Z = 1;

[0089] (2) Crystal form I includes one or more diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0090] Crystal form II satisfies at least one of the following conditions:

[0091] (1) The space group of crystal form II is Cm, and the unit cell parameters are a = 11.85±0.02 Å, b = 7.21±0.02 Å, c = 8.06±0.02 Å, alpha = 90°, beta = 128.40±0.02°, gamma = 90°, Z = 2;

[0092] (2) Crystal form II includes a diffraction peak at 19.1°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

[0093] According to embodiments of this disclosure, the flux method includes: mixing seed crystal, raw materials and flux evenly to obtain a first mixture; heating the first mixture to 120-350°C at a rate of 20-40°C / h under vacuum conditions, holding the temperature for 10-48h, and cooling it to 30°C to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20mm.

[0094] According to embodiments of this disclosure, the cooling can be carried out at a rate of 1~3℃ / day to 30℃, or a staged cooling method can be adopted, especially in the later stage of crystal growth, the cooling rate can be appropriately accelerated.

[0095] According to embodiments of this disclosure, the flux can be one or more of NH4F, NH4F:H3BO3, NH4F:B2O3, H3BO3, or B2O3.

[0096] Specifically, the flux method may include: mixing the seed crystal, raw materials, and flux evenly, placing the mixture into a quartz tube, and evacuating the quartz tube to a vacuum level of 1×10⁻⁶. −3 Pa is vacuum-sealed using a flame gun; the quartz tube is placed in a resistance furnace and heated to 120-350°C at a rate of 20-40°C / h, held at that temperature for 10-48h, and then cooled to 30°C to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20mm.

[0097] Preferably, crystal growth of seed crystal of crystal form I using the flux method may include: mixing seed crystal, raw materials and flux evenly to obtain a first mixture; heating the first mixture to 150 to 350°C at a rate of 20 to 40°C / h under vacuum conditions, holding it at the temperature for 10 to 48 hours, cooling it to 50 to 100°C at a rate of 1 to 3°C / day, and then cooling it to 30°C at a rate of 1 to 10°C / h to obtain a guanidine fluoride nonlinear optical crystal with a size of 1 to 20 mm.

[0098] Preferably, crystal growth of crystal type II seed crystal using the flux method may include: mixing the seed crystal, raw materials and flux evenly to obtain a first mixture; heating the first mixture to 120 to 260°C at a rate of 20 to 40°C / h under vacuum conditions, holding it at the temperature for 10 to 48 hours, and then cooling it to 30°C at a rate of 1 to 3°C / day to obtain a guanidine fluoride nonlinear optical crystal with a size of 1 to 20 mm.

[0099] According to embodiments of this disclosure, the crucible lowering method includes: placing a sealed container containing seed crystals and raw materials in a crucible lowering furnace, heating it to 200~450°C, and holding it at that temperature for 10~20 hours; adjusting the position of the sealed container so that the spontaneous nucleation temperature or inoculation temperature is between 250~500°C, and then slowly lowering the container at a rate of 0.05~2 mm / h, while keeping the growth temperature constant or slowly cooling it at a rate of 0~3°C / h; after the growth is completed, lowering the temperature of the growth furnace to 30°C to obtain a guanidine fluoride nonlinear optical crystal with a size of 1~20 mm.

[0100] Preferably, the crystal growth of seed crystal of crystal form I using the crucible lowering method may include: placing a sealed container containing the seed crystal and raw materials in a crucible lowering furnace, heating it to 300~450℃, and holding it at that temperature for 10~20h; adjusting the position of the sealed container so that the spontaneous nucleation temperature or inoculation temperature is 350~500℃, and then slowly lowering the container at a rate of 0.05~2mm / h, while keeping the growth temperature constant or slowly cooling it at a rate of 0~3℃ / h; after the growth is completed, lowering the temperature of the growth furnace to 30℃ to obtain a guanidine fluoride nonlinear optical crystal with a size of 1~20mm.

[0101] Preferably, the crystal growth of crystal type II seed crystal using the crucible lowering method may include: placing a sealed container containing the seed crystal and raw materials in a crucible lowering furnace, heating it to 200~350℃, and holding it at that temperature for 10~20h; adjusting the position of the sealed container so that the spontaneous nucleation temperature or inoculation temperature is 250~400℃, and then slowly lowering the container at a rate of 0.05~2mm / h, while keeping the growth temperature constant or slowly cooling it at a rate of 1~3℃ / h; after the growth is completed, lowering the temperature of the growth furnace to 30℃ to obtain a guanidine fluoride nonlinear optical crystal with a size of 1~20mm.

[0102] According to embodiments of this disclosure, the room temperature solution method includes: mixing a seed crystal, a raw material, and a second solvent to obtain a second mixture; and evaporating the second solvent in the second mixed solution at room temperature to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20 mm.

[0103] According to embodiments of this disclosure, the second solvent is one or more of deionized water, fluoroboric acid, or hydrofluoric acid.

[0104] Specifically, the room temperature solution method may include: mixing seed crystals, raw materials, and a second solvent to obtain a second mixture; adjusting the pH of the solution of the second mixture to 1-11, filtering with qualitative filter paper, sealing with a polyvinyl chloride film, placing it in a static environment without shaking, pollution, or air convection, punching several small holes in the seal to adjust the evaporation rate of the solvent in the solution, and letting it stand at room temperature for 2-168 hours until growth is complete, thereby obtaining a guanidine fluoride nonlinear optical crystal with a size of 1-20 mm.

[0105] According to embodiments of this disclosure, the solvothermal method includes: mixing a seed crystal, raw materials, and a third solvent to obtain a third mixture; placing the third mixture in a sealed container, heating it to 120-220°C at a rate of 20-40°C / h, holding it at that temperature for 10-48h, and then cooling it to room temperature at a rate of 3-10°C / day to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20mm.

[0106] According to embodiments of this disclosure, the third solvent is one or more of hexafluorophosphate, fluoroboric acid C(NH2)3HF2 aqueous solution, or hydrofluoric acid.

[0107] Preferably, crystal growth of crystal type I seed crystal by solvothermal method may include: mixing seed crystal, raw material and third solvent to obtain third mixture; placing third mixture in sealed container, heating to 120~220℃ at a rate of 20~40℃ / h, holding at temperature for 10~48h, and then cooling to room temperature at a rate of 5~10℃ / day to obtain guanidine fluoride nonlinear optical crystal with size of 1~20mm.

[0108] Preferably, crystal growth of crystal type II seed crystal using a solvothermal method may include: mixing the seed crystal, raw materials and a third solvent to obtain a third mixture; placing the third mixture in a sealed container, heating it to 120-220°C at a rate of 20-40°C / h, holding it at the temperature for 10-48h, and then cooling it to room temperature at a rate of 3-5°C / day to obtain a guanidine fluoride nonlinear optical crystal with a size of 1-20mm.

[0109] According to embodiments of this disclosure, the raw materials include guanidine-containing compounds, boron-containing compounds, and fluorine-containing compounds; the guanidine-containing compounds and fluorine-containing compounds may be the same or different.

[0110] According to embodiments of this disclosure, the guanidine-containing compound is one or more of C(NH2)3BF4, C(NH2)3F, C(NH2)3HF2, or C(NH2)3CO3 and C(NH2)3Cl. According to embodiments of this disclosure, the boron-containing compound is one or more of boric acid, boron oxide, and soluble borate. Exemplarily, the boron-containing compound can be one or more of HBO2, H3BO3, B2O3, K2B2O4·3H2O, and C(NH2)3BF4. According to embodiments of this disclosure, the fluorine-containing compound is one or more of C(NH2)3F, C(NH2)3HF2, HBF4, C(NH2)3BF4, or HF.

[0111] According to embodiments of this disclosure, the containers used in the above preparation and crystal growth methods are platinum crucibles, iridium crucibles, ceramic crucibles, quartz tubes, conical flasks, beakers, and hydrothermal reactors with polytetrafluoroethylene (PTFE) linings or stainless steel linings fitted with platinum sleeves. When the container is a quartz tube, a vacuum must be applied before sealing to prevent gas release during the reaction from causing the quartz tube to crack. When the container is a conical flask or beaker, it must first be cleaned with acid, then rinsed with deionized water, and dried. The resistance furnace used is a muffle furnace or a drying oven.

[0112] According to another aspect of this disclosure, the application of the guanidine fluoride borate compound or the guanidine fluoride borate nonlinear optical crystal grown by the above-described crystal growth method in the optical field, particularly in optical frequency doubling, optical parametric amplification, and optical parametric oscillation. The optical frequency doubling can be 2nd, 3rd, 4th, 5th, or 6th harmonics, etc.

[0113] According to embodiments of this disclosure, a large-size nonlinear optical crystal provided in these embodiments can be used. Based on the crystallographic data of the crystal, the crystal blank is oriented, cut to the required angle, thickness, and cross-sectional dimensions, and the light-transmitting surface of the crystal is polished. This allows it to be used as a nonlinear optical device. This nonlinear optical crystal has advantages such as a wide light transmission band, stable physicochemical properties, high mechanical hardness, resistance to breakage and deliquescence, and ease of cutting, polishing, and storage.

[0114] The nonlinear optical crystals provided in this disclosure can be applied to the infrared-visible-ultraviolet-deep ultraviolet bands.

[0115] Specifically, the applications of guanidine fluoride borate nonlinear optical crystals can include:

[0116] (1) Used to output harmonic light at 2nd, 3rd, 4th, 5th or 6th harmonics from the 1064 nm fundamental frequency light output by the Nd:YAG laser;

[0117] (2) Used to generate deep ultraviolet frequency-doubled light output below 200nm;

[0118] (3) Used to prepare frequency multiplier generators, up or down frequency converters, and optical parametric oscillators.

[0119] The following detailed description provides several specific embodiments to illustrate the technical solutions of this disclosure. It should be noted that the specific embodiments described below are merely examples and are not intended to limit this disclosure.

[0120] Examples 1-24

[0121] Examples 1-24 provide a guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6. This guanidine fluoride borate compound is prepared by a hydrothermal method, comprising the following steps:

[0122] A guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound were mixed uniformly in a specific molar ratio and placed into a clean, uncontaminated hydrothermal reactor lined with polytetrafluoroethylene (PTFE). Deionized water was added to ensure thorough mixing and dissolution, and the reactor was then tightly sealed. The reactor was placed in a drying oven and heated to a preset temperature at a controlled rate, held at that temperature for a period of time, and then cooled to 30°C at a controlled rate to obtain the guanidine fluoride borate compound. The guanidine fluoride borate compounds provided in Examples 1-13 are crystal form I, and the guanidine fluoride borate compounds provided in Examples 14-24 are crystal form II.

[0123] The preparation conditions for Examples 1-24 are detailed in Table 1. The molar ratio of the three compounds is the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound, and the total weight of the three compounds is the total weight of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound. The HF used was a 40 wt% aqueous solution, the HBF4 used was a 60 wt% aqueous solution, and the HPF6 used was a 60 wt% aqueous solution.

[0124] Table 1

[0125]

[0126] Examples 25-53

[0127] Examples 25-53 provide a guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6. This guanidine fluoride borate compound is prepared by a solvent method, comprising the following steps:

[0128] A guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound were mixed uniformly in a specific molar ratio and placed in a polytetrafluoroethylene (PTFE) beaker. A certain amount of solvent was added, and the mixture was stirred at a mixing temperature to ensure complete mixing and dissolution of the compounds, resulting in a mixed solution. The container containing the mixed solution was sealed with a polyvinyl chloride (PVC) film and placed in a static environment free from shaking, contamination, and air convection. Several small holes were punched in the seal to adjust the evaporation rate of the solvent in the solution. The container was left to stand at room temperature, and crystals gradually precipitated from the solution. After the growth was complete, the product in the PTFE beaker was quickly washed with deionized water and dried at room temperature to obtain the guanidine fluoride borate compound. Among them, the guanidine fluoride borate compounds provided in Examples 25-38 are crystal form I, and the guanidine fluoride borate compounds provided in Examples 39-53 are crystal form II.

[0129] The preparation conditions for Examples 25-53 are detailed in Table 2. The molar ratio of the three compounds is the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound, and the total weight of the three compounds is the total weight of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound. The HF used was a 40 wt% aqueous solution, the HBF4 used was a 60 wt% aqueous solution, and the HPF6 used was a 60 wt% aqueous solution.

[0130] Table 2

[0131]

[0132] Examples 54-63

[0133] Examples 54-63 provide a guanidine fluoride borate compound with the chemical formula (C(NH2)3)2B2OF6. This guanidine fluoride borate compound is prepared by an evaporation method, comprising the following steps:

[0134] A guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound were mixed evenly and thoroughly ground. A certain amount of deionized water was added, and the mixture was stirred at a mixing temperature to ensure complete dissolution and mixing, resulting in a mixed solution. The mixed solution was then placed in a beaker and subjected to ultrasonic treatment to ensure complete dissolution and mixing. The solution was filtered through qualitative filter paper. The beaker containing the mixed solution was placed in a constant temperature chamber, which was heated to the evaporation temperature at a specific rate and held at this temperature for a period of time (stationary). Once growth was complete, the guanidine fluoride borate compound was obtained. The guanidine fluoride borate compounds provided in Examples 54-58 were of crystal form I, and the guanidine fluoride borate compounds provided in Examples 59-63 were of crystal form II.

[0135] The preparation conditions for Examples 54-63 are detailed in Table 3. The molar ratio of the three compounds is the molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound, and the total weight of the three compounds is the total weight of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound. The HF used was a 40 wt% aqueous solution, the HBF4 used was a 60 wt% aqueous solution, and the HPF6 used was a 60 wt% aqueous solution.

[0136] Table 3

[0137]

[0138] Example 64

[0139] The guanidine fluoride borate compound (crystal form I) provided in Example 1 was used as a seed crystal for crystal growth using a room temperature solution method. The specific steps are as follows:

[0140] The seed crystal, raw materials, and second solvent are mixed to obtain a second mixture. The pH of the solution of the second mixture is adjusted to 7, filtered with qualitative filter paper, sealed with a polyvinyl chloride film, and placed in a static environment without shaking, pollution, or air convection. Several small holes are punched in the seal to adjust the evaporation rate of the solvent in the solution. After standing at room temperature for 50 hours until the growth is complete, a guanidine fluoride nonlinear optical crystal with a size in the centimeter range is obtained.

[0141] Example 65

[0142] The guanidine fluoride borate compound (crystal form II) provided in Example 16 was used as a seed crystal for crystal growth using the room temperature solution method. The specific steps are the same as in Example 70 and will not be repeated here.

[0143] Application Example 1

[0144] The guanidine fluoride borate nonlinear optical crystals provided in Examples 64 and 65 were processed according to matching directions, and then... Figure 5 As shown, the laser is positioned at position 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 1064nm. The infrared beam with a wavelength of 1064nm emitted by the Q-switched Nd:YAG laser 1 is focused by the convex lens 2 and enters the nonlinear optical crystal 3, producing green frequency-doubled light with a wavelength of 532nm. After being split by the prism 4 and filtered by the filter 5, the output intensity is approximately 1.5 or 3 times that of KDP under the same conditions.

[0145] Application Example 2

[0146] The guanidine fluoride borate nonlinear optical crystals provided in Examples 64 and 65 were processed according to matching directions, and then... Figure 5 As shown, the laser is positioned at position 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 532nm. The infrared beam with a wavelength of 532nm emitted by the Q-switched Nd:YAG laser 1 is focused by the convex lens 2 and enters the nonlinear optical crystal 3, producing a frequency-doubled light with a wavelength of 266nm. After being split by the prism 4 and filtered by the filter 5, the output intensity is approximately 1.5 times that of BBO under the same conditions.

[0147] Application Example 3

[0148] The guanidine fluoride borate nonlinear optical crystals provided in Examples 64 and 65 were processed according to matching directions, and then... Figure 5 As shown, the laser beam is positioned at position 3. At room temperature, a Q-switched Nd:YAG laser is used as the light source with an incident wavelength of 355nm. The infrared beam with a wavelength of 355nm emitted by the Q-switched Nd:YAG laser 1 is focused by the convex lens 2 and enters the nonlinear optical crystal 3. After being split by the prism 4 and filtered by the filter 5, the deep ultraviolet frequency-doubled light output with a wavelength of 193.3nm can be observed.

[0149] Stability test:

[0150] The guanidine fluoride borate nonlinear optical crystals provided in Examples 64 and 65 were observed at room temperature. After 30 days, the nonlinear optical crystals showed no significant changes and maintained good light transmittance.

[0151] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, or improvements made by those skilled in the art to the technical methods within the spirit and principles of this disclosure shall still be included within the protection scope of the technical solution of this disclosure.

Claims

1. A guanidine fluoride borate compound, wherein, The chemical formula of the guanidine fluoride borate compound is (C(NH2)3)2B2OF6.

2. The guanidine fluoride borate compound according to claim 1, wherein, The guanidine fluoride borate compound has a nonlinear optical crystal structure belonging to the monoclinic crystal system, including crystal form I and / or crystal form II; Wherein, the space group of crystal form I is Cc, and the unit cell parameters are a = 12.58±0.02 Å, b = 7.34±0.02 Å, c = 13.02±0.02 Å, alpha = 90°, beta = 114.27±0.02°, gamma = 90°, Z = 1; The space group of the crystal form II is Cm, and the cell parameters are a = 11.85 ± 0.02 Å, b = 7.21 ± 0.02 Å, c = 8.06 ± 0.02 Å, alpha = 90°, beta = 128.40 ± 0.02°, gamma = 90°, and Z = 2.

3. The guanidine fluoride borate compound according to claim 1, wherein, The guanidine fluoride borate compound includes crystal form I and / or crystal form II; The crystal form I includes one or more diffraction peaks at 17.6°±0.2°, 18.3°±0.2°, 22.9°±0.2°, and 32.5°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ; The crystal form II includes a diffraction peak at 19.1°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

4. The guanidine fluoride borate compound according to claim 3, wherein, The crystal form I also includes one or more diffraction peaks at 14.6°±0.2°, 15.4°±0.2°, 16.5°±0.2°, 24.5°±0.2°, 27.6°±0.2°, 29.3°±0.2°, and 30.1°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ; The crystal form II also includes one or more diffraction peaks at 14.0°±0.2°, 15.5°±0.2°, 16.5°±0.2°, 24.7°±0.2°, 27.7°±0.2°, 30.5°±0.2°, and 31.4°±0.2° in the X-ray powder diffraction pattern with a diffraction angle of 2θ.

5. A method for preparing a guanidine fluoride borate compound according to any one of claims 1 to 4, comprising the following steps: A guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound are reacted to obtain a guanidine fluoride borate compound; The guanidine-containing compound and the fluorine-containing compound may be the same or different.

6. The preparation method according to claim 5, wherein, The reaction of a guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound to obtain a guanidine fluoride borate compound includes: A guanidine-containing compound, a boron-containing compound, and a fluorine-containing compound are mixed with a first solvent to obtain a mixed solution; and The guanidine fluoride borate compound is obtained by reacting the mixed solution using a hydrothermal method, a solvent method, or an evaporation method. The hydrothermal method includes: placing the mixed solution in a sealed container, heating it to 160-230°C at a rate of 20-60°C / h, maintaining the temperature for 3-15 days, and then cooling it to room temperature at a rate of 2-10°C / h to obtain the guanidine fluoride borate compound. The solvent method includes: evaporating the first solvent in the mixed solution at room temperature to obtain the guanidine fluoride borate compound; The evaporation method includes: heating the mixed solution to 50-120°C at a rate of 5-10°C / h, evaporating the first solvent, and obtaining the guanidine fluoride borate compound.

7. The preparation method according to claim 6, wherein, In the hydrothermal method, the first solvent is water; In the solvent method, the first solvent is one or more of water, ethanol, hydrofluoric acid, or tetrafluoroboric acid; In the evaporation method, the first solvent is water.

8. The preparation method according to claim 5, wherein, The guanidine-containing compound is one or more of C(NH2)3BF4, C(NH2)3F, C(NH2)3HF2, C(NH2)3CO3, and C(NH2)3Cl; The boron-containing compound is one or more selected from boric acid, boron oxide, and soluble borates; The fluorinated compound is one or more of C(NH2)3F, C(NH2)3HF2, HBF4, C(NH2)3BF4 or HF; The molar ratio of the guanidine-containing compound, the boron-containing compound, and the fluorine-containing compound is (0.5~2):(1~5):(0~4).

9. A crystal growth method, comprising: Crystal growth is achieved by using a flux method, crucible lowering method, room temperature solution method, or solvothermal method to grow a seed crystal, resulting in a guanidine fluoride nonlinear optical crystal with a size of 1-20 mm. The seed crystal is a nonlinear optical crystal of guanidine fluoride compound (C(NH2)3)2B2OF6, including crystal form I or crystal form II. Wherein, the space group of crystal form I is Cc, and the unit cell parameters are a = 12.58±0.02 Å, b = 7.34±0.02 Å, c = 13.02±0.02 Å, alpha = 90°, beta = 114.27±0.02°, gamma = 90°, Z = 1; The space group of the crystal form II is Cm, and the cell parameters are a = 11.85 ± 0.02 Å, b = 7.21 ± 0.02 Å, c = 8.06 ± 0.02 Å, alpha = 90°, beta = 128.40 ± 0.02°, gamma = 90°, and Z = 2.

10. The application of a guanidine fluoride borate compound according to any one of claims 1 to 4 or a guanidine fluoride borate nonlinear optical crystal grown by the crystal growth method according to claim 9 in optical frequency doubling, optical parametric amplification, or optical parametric oscillation.

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