Compound potassium fluoborate and potassium fluoborate nonlinear optical crystal and preparation method and use

Abstract

This invention relates to a compound, potassium fluoroborate, a nonlinear optical crystal of potassium fluoroborate, its preparation method, and its uses. The chemical formula of the compound is K₂B₂OF₆, and its molecular weight is 229.82. It is prepared by a room temperature solution method or a hydrothermal method. The crystal belongs to the hexagonal crystal system, with space group P₆(_)₂m, and cell parameters a=9.1105(13)Å, b=9.1105(13)Å, c=6.9919(17)Å, α=90°, β=90°, γ=120°, Z=3, and V=502.59(16)Å. 3 Potassium fluoroborate nonlinear optical crystals obtained by growing crystals using room-temperature solution methods, hydrothermal methods, or high-temperature melt methods possess advantages such as a wide transmission band, stable physicochemical properties, moderate mechanical hardness, resistance to breakage, and ease of cutting, polishing, and storage. They can be widely used in nonlinear optical devices such as frequency doubling converters and optical parametric oscillators.

Description

Technical Field

[0001] This invention relates to a compound potassium fluoroborate K2B2OF6 and a potassium fluoroborate K2B2OF6 nonlinear optical crystal, as well as their preparation methods and uses. Background Technology

[0002] Short-wavelength nonlinear optical crystals can utilize their frequency conversion properties to convert near-infrared and visible lasers into short-wavelength lasers, which has significant application value in fields such as medicine, communications, and scientific research. Therefore, in the past few decades, scientists have invented several short-wavelength nonlinear optical crystals in the ultraviolet and deep ultraviolet bands, including β-BaB₂O₄ (BBO), LiB₃O₅ (LBO), CsB₃O₅ (CBO), and CsLiB₆O₅. 10 Examples include (CLBO), KBe₂BO₃F₂ (KBBF), and NH₄B₄O₆F (ABF). It is well known that the only practically applicable deep-ultraviolet nonlinear optical crystal is the (KBBF) crystal invented by Chinese scientists. This crystal exhibits a layered growth habit, making the growth of large-size crystals difficult, which limits its applications to some extent. Scientists worldwide continue to focus on the exploration and research of various novel nonlinear optical crystals, emphasizing not only their optical and mechanical properties but also increasingly their fabrication characteristics. Therefore, the preparation and synthesis of novel short-wavelength nonlinear optical crystal materials with excellent comprehensive performance is of great significance and practical value. Summary of the Invention

[0003] The purpose of this invention is to provide a compound, potassium fluoroborate, with the chemical formula K2B2OF6 and a molecular weight of 229.82, which is prepared by room temperature solution method and hydrothermal method.

[0004] Another object of the present invention is to provide a potassium fluoroborate nonlinear optical crystal with the chemical formula K₂B₂OF₆, a molecular weight of 229.82, belonging to the hexagonal crystal system, space group P₆2m, and cell parameters of [missing information]. α=90°, β=90°, γ=120°, Z=3,

[0005] Another objective of this invention is to provide a method for preparing potassium fluoroborate nonlinear optical crystals, using a room temperature solution method, a hydrothermal method, or a high-temperature melt method.

[0006] Another object of the present invention is to provide the use of potassium fluoroborate nonlinear optical crystals.

[0007] The present invention discloses a compound, potassium fluoroborate, with the chemical formula K2B2OF6 and a molecular weight of 229.82, which is prepared by room temperature solution method or hydrothermal method.

[0008] The potassium fluoroborate compound is prepared by a room temperature solution method or a hydrothermal method, and the specific operation is carried out according to the following steps:

[0009] The compound potassium fluoroborate was prepared using a room temperature solution method.

[0010] a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, place them in a clean container, add 5-30 mL of deionized water, and stir to fully mix and dissolve the compounds; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2;

[0011] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 5-30 days until crystals gradually precipitate in the solution, at which point the reaction is complete. Then, quickly wash the product in the container with deionized water and air dry it at room temperature to obtain compound K2B2OF6.

[0012] The compound potassium fluoroborate was prepared using a hydrothermal method.

[0013] a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, add 0.5-6 mL of deionized water to fully mix and dissolve, and obtain a mixed solution; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2;

[0014] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150-230℃ at a rate of 20-50℃ / h, keep the temperature constant for 2-5 days, and slowly lower it to room temperature.

[0015] c. Open the high-pressure reactor, filter the product in the liner and wash it quickly with deionized water, and dry it at room temperature to obtain compound K2B2OF6.

[0016] A potassium fluoroborate nonlinear optical crystal, with the chemical formula K₂B₂OF₆, belonging to the hexagonal crystal system and space group [missing information]. Cell parameters are α=90°, β=90°, γ=120°, Z=3,

[0017] The method for preparing the potassium fluoroborate nonlinear optical crystal involves growing the crystal using a room temperature solution method, a hydrothermal method, or a high-temperature melt method.

[0018] The potassium fluoroborate nonlinear optical crystal is grown using a room temperature solution method.

[0019] a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, place them in a polytetrafluoroethylene beaker, add 20-100 mL of deionized water, and stir to fully mix and dissolve the compounds; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2;

[0020] b. Seal the polytetrafluoroethylene beaker containing the solution from step a with a polyvinyl chloride film, place it in a static environment without shaking, pollution, or air convection, poke several small holes in the seal to adjust the evaporation rate, and let it stand for 5-30 days; wait for crystal particles to grow at the bottom of the container until the size of the crystal particles no longer changes significantly, the growth is complete, and seed crystals are obtained.

[0021] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 10-40 days to obtain the K2B2OF6 nonlinear optical crystal.

[0022] The potassium fluoroborate nonlinear optical crystal is grown using a hydrothermal method.

[0023] a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, add 5-30 mL of deionized water to fully mix and dissolve, and obtain a mixed solution; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2;

[0024] b. Transfer the mixed solution from step a into the liner of a high-pressure reactor with a volume of 23-100 mL, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150-230℃ at a rate of 20-50℃ / h, keep the temperature constant for 2-5 days, and slowly lower it to room temperature.

[0025] c. Open the high-pressure reactor and obtain millimeter-sized K2B2OF6 nonlinear optical crystals from the colorless, clear solution;

[0026] The potassium fluoroborate nonlinear optical crystal is grown using a high-temperature melt method.

[0027] a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, place the mixture in a platinum crucible, heat it to 250-400℃ in a muffle furnace, hold it at that temperature for 2-5 days, and then slowly cool it to room temperature to obtain the polycrystalline powder of compound K2B2OF6; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2;

[0028] b. The polycrystalline powder of compound K2B2OF6 obtained in step a is placed in a platinum crucible, heated to 300-400℃, and kept at the temperature for 10-60 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 0.1-2℃ / h, and then rapidly reduced to room temperature at a rate of 5-10℃ / h to obtain K2B2OF6 seed crystals.

[0029] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 2-20 rpm through the crystal growth controller, and cool down at a rate of 0.1-3℃ / h. After the crystal growth stops, the K2B2OF6 nonlinear optical crystal is obtained.

[0030] The application of the potassium fluoroborate nonlinear optical crystal in the fabrication of multi-band frequency doubling devices or optical elements.

[0031] The potassium fluoroborate nonlinear optical crystal is used to prepare second-harmonic light output from the 1064nm fundamental frequency light of an Nd:YAG laser.

[0032] The potassium fluoroborate nonlinear optical crystal is used in the fabrication of frequency multiplier generators, up or down frequency converters, or optical parametric oscillators.

[0033] The method for preparing potassium fluoroborate nonlinear optical crystals according to the present invention uses a platinum crucible, a ceramic crucible, an Erlenmeyer flask, a polytetrafluoroethylene (PTFE) beaker, a plastic beaker, or a hydrothermal reactor with a PTFE liner or a stainless steel liner fitted with a platinum sleeve. When the container is an Erlenmeyer flask, a PTFE beaker, or a plastic beaker, it must first be cleaned with acid, then rinsed with deionized water, and then dried.

[0034] The method for preparing potassium fluoroborate nonlinear optical crystals described in this invention requires a muffle furnace or a drying oven as the resistance furnace used in the preparation process. Attached Figure Description

[0035] Figure 1 The XRD pattern of compound K2B2OF6 of this invention is shown below.

[0036] Figure 2 This is a structural diagram of the K2B2OF6 crystal of the present invention;

[0037] Figure 3 This is a schematic diagram of the working principle of the nonlinear optical device made of K2B2OF6 crystal of the present invention, wherein 1 is a laser, 2 is the emitted beam, 3 is a K2B2OF6 crystal, 4 is the emitted beam, and 5 is a filter. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments. It should be noted that the following embodiments are not intended to limit the scope of protection of the present invention, and any improvements made based on the present invention do not depart from the spirit of the present invention. Unless otherwise specified, the raw materials or equipment used in the present invention are commercially available.

[0039] Example 1

[0040] Preparation of compounds:

[0041] According to the reaction formula: 2KF + 2H3BO3 + 4HF → K2B2OF6 + 5H2O, compound K2B2OF6 was synthesized by room temperature solution method.

[0042] a. Mix KF, ​​H3BO3 and HF evenly in a molar ratio of 2.2:1.8:4, put them into a clean container, add 10 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0043] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 5 days until crystals gradually precipitate in the solution. The reaction is then complete. Quickly wash the product in the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0044] Example 2

[0045] Preparation of compounds:

[0046] According to the reaction formula: 2KF + B₂O₃ + 4HF → K₂B₂OF₆ + 2H₂O, compound K₂B₂OF₆ was synthesized by room temperature solution method.

[0047] a. Mix KF, ​​B2O3 and HF evenly in a molar ratio of 2.2:1.1:4.2, put them into a clean plastic container, add 15 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0048] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 10 days until crystals gradually precipitate in the solution. The reaction is then complete. Quickly wash the product in the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0049] Example 3

[0050] Preparation of compounds:

[0051] According to the reaction formula: KBF4 + KF + H3BO3 + HF → K2B2OF6 + 2H2O, compound K2B2OF6 was synthesized by room temperature solution method.

[0052] a. Mix KBF4, KF, H3BO3, and HF evenly in a molar ratio of 1:1.4:1.1:0.8, put the mixture into a clean container, add 15 mL of deionized water, and stir to fully mix and dissolve the compounds.

[0053] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment free from shaking, contamination, and air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 20 days. Once crystals gradually precipitate from the solution, the reaction is complete. Quickly wash the product from the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0054] Example 4

[0055] Preparation of compounds:

[0056] According to the reaction formula: KBF4 + KF + 0.5B2O3 + HF → K2B2OF6 + 0.5H2O, compound K2B2OF6 was synthesized by room temperature solution method.

[0057] a. Mix KBF4, KF, B2O3 and HF evenly in a molar ratio of 1:0.6:0.7:1.1, put them into a clean container, add 15 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0058] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment free from shaking, contamination, and air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 25 days. Once crystals gradually precipitate from the solution, the reaction is complete. Quickly wash the product from the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0059] Example 5

[0060] Preparation of compounds:

[0061] According to the reaction formula: 2KHF₂ + 2HBO₂ + 2HF → K₂B₂OF₆ + 3H₂O, compound K₂B₂OF₆ was synthesized by room temperature solution method.

[0062] a. Mix KHF2, HBO2 and HF evenly in a molar ratio of 2.2:2.4:1.7, put them into a clean container, add 20 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0063] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 30 days until crystals gradually precipitate in the solution. The reaction is then complete. Quickly wash the product in the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0064] Example 6

[0065] Preparation of compounds:

[0066] According to the reaction formula: KBF4 + KHF2 + HBO2 → K2B2OF6 + H2O, compound K2B2OF6 was synthesized by room temperature solution method.

[0067] a. Mix KBF4, KHF2 and HBO2 evenly in a molar ratio of 1:1.1:0.9, put them into a clean container, add 15 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0068] b. Seal the container containing the solution with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make small holes in the seal to control the evaporation rate. Let it stand at room temperature for 15 days until crystals gradually precipitate in the solution. The reaction is then complete. Quickly wash the product in the container with deionized water and air dry at room temperature to obtain compound K2B2OF6.

[0069] Example 7

[0070] Preparation of compounds:

[0071] According to the reaction formula: 0.5K₂B₄O₇·4H₂O + KF + 5HF → K₂B₂OF₆ + 4.5H₂O, compound K₂B₂OF₆ was synthesized by hydrothermal method.

[0072] a. Mix K2B4O7·4H2O, KF and HF evenly in a molar ratio of 0.5:1.4:5, add 1 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0073] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 230 °C at a rate of 50 °C / h, keep the temperature constant for 4 days, and slowly lower it to room temperature.

[0074] c. Open the high-pressure reactor, filter the product in the liner and quickly wash it with deionized water to obtain compound K2B2OF6.

[0075] Example 8

[0076] Preparation of compounds:

[0077] According to the reaction formula: KBF4 + KHF2 + H3BO3 → K2B2OF6 + 2H2O, compound K2B2OF6 was synthesized by hydrothermal method.

[0078] a. Mix KBF4, KHF2 and H3BO3 evenly in a molar ratio of 1:1.1:0.8, add 0.5 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0079] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150 °C at a rate of 20 °C / h, keep the temperature constant for 4 days, and slowly lower it to room temperature.

[0080] c. Open the high-pressure reactor, filter the product in the liner and quickly wash it with deionized water to obtain compound K2B2OF6.

[0081] Example 9

[0082] Preparation of compounds:

[0083] According to the reaction formula: 2KHF2 + 2H3BO3 + 2HF → K2B2OF6 + 5H2O, compound K2B2OF6 was synthesized by hydrothermal method.

[0084] a. Mix KHF2, H3BO3 and HF evenly in a molar ratio of 1.6:2.4:2, add 2 mL of deionized water to fully mix and dissolve, and obtain a mixed solution;

[0085] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 180 °C at a rate of 30 °C / h, keep the temperature constant for 3 days, and slowly lower it to room temperature.

[0086] c. Open the high-pressure reactor, filter the product in the liner and quickly wash it with deionized water to obtain compound K2B2OF6.

[0087] Example 10

[0088] Preparation of compounds:

[0089] According to the reaction formula: 2KHCO3 + 2H3BO3 + 6HF → K2B2OF6 + 7H2O + 2CO2, compound K2B2OF6 was synthesized by hydrothermal method.

[0090] a. Mix KHCO3, H3BO3 and HF evenly in a molar ratio of 2.2:2:6.4, add 6 mL of deionized water to fully mix and dissolve, and obtain a mixed solution;

[0091] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 220 °C at a rate of 30 °C / h, keep the temperature constant for 4 days, and slowly lower it to room temperature.

[0092] c. Open the high-pressure reactor, filter the product in the liner and quickly wash it with deionized water to obtain compound K2B2OF6.

[0093] Example 11

[0094] Preparation of compounds:

[0095] According to the reaction formula: 2KOH + 2H₃BO₃ + 6HF → K₂B₂OF₆ + 7H₂O, compound K₂B₂OF₆ was synthesized by hydrothermal method.

[0096] a. Mix KOH, H3BO3 and HF evenly in a molar ratio of 2.1:1.8:6, add 5 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0097] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 200 °C at a rate of 40 °C / h, keep the temperature constant for 3 days, and slowly lower it to room temperature.

[0098] c. Open the high-pressure reactor, filter the product in the liner and quickly wash it with deionized water to obtain compound K2B2OF6.

[0099] Example 12

[0100] According to the reaction formula: 2KF + 2H3BO3 + 4HF → K2B2OF6 + 5H2O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0101] a. Mix KF, ​​H3BO3 and HF evenly in a molar ratio of 2.2:1.8:4, put them into a clean polytetrafluoroethylene beaker, add 20 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0102] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 5 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0103] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 10 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 0.9mm × 0.7mm × 0.6mm.

[0104] Example 13

[0105] According to the reaction formula: 2KF + B₂O₃ + 4HF → K₂B₂OF₆ + 2H₂O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0106] a. Mix KF, ​​B2O3 and HF evenly in a molar ratio of 2.2:1.1:4.2, put them into a clean polytetrafluoroethylene beaker, add 40 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0107] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 10 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0108] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 15 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.1mm × 0.8mm × 0.5mm.

[0109] Example 14

[0110] According to the reaction formula: KBF4 + KF + H3BO3 + HF → K2B2OF6 + 2H2O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0111] a. Mix KBF4, KF, H3BO3 and HF evenly in a molar ratio of 1:1.4:1.1:0.8, put them into a clean polytetrafluoroethylene beaker, add 60mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0112] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 20 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0113] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 20 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.3mm × 1.0mm × 0.7mm.

[0114] Example 15

[0115] According to the reaction formula: KBF4 + KF + HBO2 + HF → K2B2OF6 + H2O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0116] a. Mix KBF4, KF, HBO2 and HF evenly in a molar ratio of 1:0.6:0.7:1.1, put them into a clean polytetrafluoroethylene beaker, add 80 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0117] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 22 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0118] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 25 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.4mm × 1.0mm × 0.9mm.

[0119] Example 16

[0120] According to the reaction formula: 2KHF₂ + 2HBO₂ + 2HF → K₂B₂OF₆ + 3H₂O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0121] a. Mix KHF2, HBO2, and HF evenly in a molar ratio of 2.2:2.4:1.7, pour the mixture into a clean polytetrafluoroethylene beaker, add 100 mL of deionized water, and stir to ensure the compound is fully mixed and dissolved; the room temperature solution method is used.

[0122] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 25 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0123] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 30 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.5mm × 1.3mm × 1.0mm.

[0124] Example 17

[0125] According to the reaction formula: KBF4 + KHF2 + HBO2 → K2B2OF6 + H2O, potassium fluoroborate nonlinear optical crystals are grown using a room temperature solution method.

[0126] a. Mix KBF4, KHF2 and HBO2 evenly in a molar ratio of 1:1.1:0.9, put them into a clean polytetrafluoroethylene beaker, add 50 mL of deionized water, and stir to make the compound fully mixed and dissolved.

[0127] b. Seal the container containing the solution from step a with a polyvinyl chloride film and place it in a static environment without shaking, pollution, or air convection. Make several small holes in the seal to adjust the evaporation rate. Let it stand for 30 days until crystal particles grow at the bottom of the container. The growth ends when the size of the crystal particles no longer changes significantly. Seed crystals are obtained.

[0128] c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 40 days to obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.1mm × 1.1mm × 0.6mm.

[0129] Example 18

[0130] Potassium fluoroborate nonlinear optical crystals were grown using a hydrothermal method according to the reaction formula: 0.5K₂B₄O₇·4H₂O + KF + 5HF → K₂B₂OF₆ + 4.5H₂O.

[0131] a. Mix K2B4O7·4H2O, KF and HF evenly in a molar ratio of 0.5:1.4:5, add 5 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0132] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 230 °C at a rate of 50 °C / h, keep the temperature constant for 4 days, and slowly lower it to room temperature.

[0133] c. Open the high-pressure reactor and obtain a K2B2OF6 nonlinear optical crystal with a diameter of 0.8mm × 0.6mm × 0.5mm from the colorless, clear solution.

[0134] Example 19

[0135] According to the reaction formula: KBF4 + KHF2 + H3BO3 → K2B2OF6 + 2H2O, potassium fluoroborate nonlinear optical crystals are grown using a hydrothermal method.

[0136] a. Mix KBF4, KHF2 and H3BO3 evenly in a molar ratio of 1:1.1:0.8, add 10 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0137] b. Transfer the mixed solution from step a into the liner of a 50 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150 °C at a rate of 20 °C / h, keep it at the temperature for 2 days, and slowly lower it to room temperature.

[0138] c. Open the high-pressure reactor and obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.0mm × 0.8mm × 0.7mm from the colorless, clear solution.

[0139] Example 20

[0140] According to the reaction formula: 2KHF2 + 2H3BO3 + 2HF → K2B2OF6 + 5H2O, potassium fluoroborate nonlinear optical crystals are grown using a hydrothermal method.

[0141] a. Mix KHF2, H3BO3 and HF evenly in a molar ratio of 1.6:2.4:2, add 30 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0142] b. Transfer the mixed solution from step a into the liner of a 100 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 180 °C at a rate of 30 °C / h, keep the temperature constant for 3 days, and slowly lower it to room temperature.

[0143] c. Open the high-pressure reactor and obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.5mm × 1.1mm × 1.0mm from the colorless clear solution.

[0144] Example 21

[0145] According to the reaction formula: 2KHCO3 + 2H3BO3 + 6HF → K2B2OF6 + 7H2O + 2CO2, potassium fluoroborate nonlinear optical crystals are grown using a hydrothermal method.

[0146] a. Mix KHCO3, H3BO3 and HF evenly in a molar ratio of 2.2:2:6.4, add 30 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0147] b. Transfer the mixed solution from step a into the liner of a 100 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 200 °C at a rate of 40 °C / h, keep the temperature constant for 5 days, and slowly lower it to room temperature.

[0148] c. Open the high-pressure reactor and obtain a K2B2OF6 nonlinear optical crystal with a diameter of 1.4mm × 1.3mm × 1.0mm from the colorless, clear solution.

[0149] Example 22

[0150] According to the reaction formula: 2KOH + 2H₃BO₃ + 6HF → K₂B₂OF₆ + 7H₂O, potassium fluoroborate nonlinear optical crystals are grown using a hydrothermal method.

[0151] a. Mix KOH, H3BO3 and HF evenly in a molar ratio of 2.1:1.8:6, add 5 mL of deionized water to mix and dissolve thoroughly to obtain a mixed solution;

[0152] b. Transfer the mixed solution from step a into the liner of a 23 mL high-pressure reactor, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 230 °C at a rate of 20 °C / h, keep it at the temperature for 2 days, and slowly lower it to room temperature.

[0153] c. Open the high-pressure reactor and obtain a K2B2OF6 nonlinear optical crystal with a diameter of 0.9mm × 0.7mm × 0.6mm from the colorless, clear solution.

[0154] Example 23

[0155] Following the reaction formula: 0.5K₂B₄O₇·4H₂O + KF + 5NH₄F → K₂B₂OF₆ + 2.5H₂O + 5NH₃, potassium fluoroborate nonlinear optical crystals are grown using the high-temperature melt method.

[0156] a. Mix K2B4O7·4H2O, KF and NH4F evenly in a molar ratio of 0.5:1.4:5, put the mixture into a platinum crucible, place it in a muffle furnace and heat it to 250°C, keep it at the temperature for 2 days, and then slowly cool it down to room temperature to obtain K2B2OF6 polycrystalline powder.

[0157] b. The K2B2OF6 polycrystalline powder obtained in step a is placed in a platinum crucible, heated to 300℃, and kept at that temperature for 60 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 0.1℃ / h, and then rapidly reduced to room temperature at a rate of 5℃ / h to obtain K2B2OF6 seed crystals.

[0158] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 2 rpm through the crystal growth controller, and cool down at a rate of 0.1℃ / h. After the crystal growth stops, a K2B2OF6 nonlinear optical crystal with a diameter of 3.1mm×2.5mm×1.7mm is obtained.

[0159] Example 24

[0160] Based on the reaction formula: KBF4 + KHF2 + H3BO3 → K2B2OF6 + 2H2O, potassium fluoroborate nonlinear optical crystals are grown using a high-temperature melt method.

[0161] a. Mix KBF4, KHF2 and H3BO3 evenly in a molar ratio of 1:1.1:0.8, put the mixture into a platinum crucible, place it in a muffle furnace and heat it to 300°C. Keep the temperature constant for 3 days, and then slowly cool it to room temperature to obtain K2B2OF6 polycrystalline powder.

[0162] b. The K2B2OF6 polycrystalline powder obtained in step a is placed in a platinum crucible, heated to 350°C, and kept at that temperature for 50 hours to obtain a mixed melt. The temperature is then slowly reduced to 250°C at a rate of 0.5°C / h, and then rapidly reduced to room temperature at a rate of 7°C / h to obtain K2B2OF6 seed crystals.

[0163] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 10 rpm through the crystal growth controller, and cool down at a rate of 1℃ / h. After the crystal growth stops, a K2B2OF6 nonlinear optical crystal with a diameter of 2.5mm×2.3mm×1.5mm is obtained.

[0164] Example 25

[0165] According to the reaction formula: 2KHF2 + 2H3BO3 + NH4HF2 → K2B2OF6 + 5H2O + NH3, potassium fluoroborate nonlinear optical crystals are grown using the high-temperature melt method.

[0166] a. Mix KHF2, H3BO3 and NH4HF2 evenly in a molar ratio of 1.6:2.4:1, put the mixture into a platinum crucible, place it in a muffle furnace and heat it to 350°C. Hold the temperature for 4 days and then slowly cool it to room temperature to obtain K2B2OF6 polycrystalline powder.

[0167] b. The K2B2OF6 polycrystalline powder obtained in step a is placed in a platinum crucible, heated to 400℃, and kept at the temperature for 10 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 2℃ / h, and then rapidly reduced to room temperature at a rate of 10℃ / h to obtain K2B2OF6 seed crystals.

[0168] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 15 rpm through the crystal growth controller, and cool down at a rate of 3℃ / h. After the crystal growth stops, a nonlinear optical crystal of K2B2OF6Φ3.7mm×2.6mm×2.1mm is obtained.

[0169] Example 26

[0170] Based on the reaction formula: 2KHCO3 + 2H3BO3 + 3NH4HF2 → K2B2OF6 + 7H2O + 2CO2 + 3NH3, potassium fluoroborate nonlinear optical crystals are grown using the high-temperature melt method.

[0171] a. Mix KHCO3, H3BO3 and NH4HF2 evenly in a molar ratio of 2.2:2:3.2, put the mixture into a platinum crucible, place it in a muffle furnace and heat it to 400℃, keep it at the temperature for 2 days, and then slowly cool it down to room temperature to obtain K2B2OF6 polycrystalline powder.

[0172] b. The K2B2OF6 polycrystalline powder obtained in step a is placed in a platinum crucible, heated to 300℃, and kept at that temperature for 40 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 1℃ / h, and then rapidly reduced to room temperature at a rate of 8℃ / h to obtain K2B2OF6 seed crystals.

[0173] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 15 rpm through the crystal growth controller, and cool down at a rate of 2℃ / h. After the crystal growth stops, a K2B2OF6 nonlinear optical crystal with a diameter of 2.7mm×1.9mm×1.7mm is obtained.

[0174] Example 27

[0175] According to the reaction formula: 2KOH + 2H3BO3 + 6NH4F → K2B2OF6 + 7H2O + 6NH3, potassium fluoroborate nonlinear optical crystals are grown using the high-temperature melt method.

[0176] a. Mix KOH, H3BO3 and NH4F evenly in a molar ratio of 2.1:1.8:6, put the mixture into a platinum crucible, place it in a muffle furnace and heat it to 28°C. Keep the temperature constant for 5 days, and then slowly cool it to room temperature to obtain K2B2OF6 polycrystalline powder.

[0177] b. The K2B2OF6 polycrystalline powder obtained in step a is placed in a platinum crucible, heated to 380℃, and kept at that temperature for 30 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 2℃ / h, and then rapidly reduced to room temperature at a rate of 10℃ / h to obtain K2B2OF6 seed crystals.

[0178] c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 20 rpm through the crystal growth controller, and cool down at a rate of 3℃ / h. After the crystal growth stops, a K2B2OF6 nonlinear optical crystal with a diameter of 3.0mm×2.6mm×2.1mm is obtained.

[0179] Example 28

[0180] Process any one of the potassium fluoroborate nonlinear optical crystals obtained in Examples 12-27 according to a matching direction, and according to the attached... Figure 3 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. An infrared beam with a wavelength of 1064nm emitted by the Q-switched Nd:YAG laser 1 is incident on the single crystal 3, producing green frequency-doubled light with a wavelength of 532nm. The output intensity is approximately 0.1-1.5 times that of KDP under the same conditions.

Claims

1. A potassium fluoroborate nonlinear optical crystal, characterized in that... The crystal has the chemical formula K₂B₂OF₆, belongs to the hexagonal crystal system, and has the space group [space group number missing]. The unit cell parameters are a = 9.1105(13) Å, b = 9.1105(13) Å, c = 6.9919(17) Å, α = 90°, β = 90°, γ = 120°, Z = 3, V = 502.59(16) Å. 3 .

2. A method for preparing a potassium fluoroborate nonlinear optical crystal as described in claim 1, characterized in that... Crystals are grown using room temperature solution method, hydrothermal method, or high temperature melt method; The potassium fluoroborate nonlinear optical crystal is grown using a room temperature solution method. a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, place them in a polytetrafluoroethylene beaker, add 20-100 mL of deionized water, and stir to fully mix and dissolve the compounds; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2; b. Seal the polytetrafluoroethylene beaker containing the solution from step a with a polyvinyl chloride film, place it in a static environment without shaking, pollution, or air convection, poke several small holes in the seal to adjust the evaporation rate, and let it stand for 5-30 days; wait for crystal particles to grow at the bottom of the container until the size of the crystal particles no longer changes significantly, the growth is complete, and seed crystals are obtained. c. Filter the remaining solution from step b with qualitative filter paper to remove the crystal grains and other impurities in the solution. Select a seed crystal of good quality, fix the seed crystal with platinum wire, suspend it in the filtered solution, seal the opening with small holes to control the evaporation rate, and let it stand at room temperature for 10-40 days to obtain the K2B2OF6 nonlinear optical crystal. The potassium fluoroborate nonlinear optical crystal is grown using a hydrothermal method. a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, add 5-30 mL of deionized water to fully mix and dissolve, and obtain a mixed solution; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, KBF4, KHF2, HF, NH4F, or NH4HF2; b. Transfer the mixed solution from step a into the liner of a high-pressure reactor with a volume of 23-100 mL, tighten and seal the high-pressure reactor, then place the high-pressure reactor in a constant temperature chamber, raise the temperature to 150-230℃ at a rate of 20-50℃ / h, keep the temperature constant for 2-5 days, and slowly lower it to room temperature. c. Open the high-pressure reactor and obtain millimeter-sized K2B2OF6 nonlinear optical crystals from the colorless, clear solution; The potassium fluoroborate nonlinear optical crystal is grown using a high-temperature melt method. a. Mix the K-containing compound, B-containing compound, and F-containing compound evenly in a molar ratio of 1.6-2.4∶1.8-2.4∶5.2-6.4, place the mixture in a platinum crucible, heat it to 250-400℃ in a muffle furnace, hold it at that temperature for 2-5 days, and then slowly cool it to room temperature to obtain the polycrystalline powder of compound K2B2OF6; wherein the K-containing compound is KF, KBF4, KHF2, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, K2CO3, KHCO3, or KOH, the B-containing compound is H3BO3, B2O3, HBO2, KBF4, K2B4O7·4H2O, KBO2, K2B2O4·3H2O, or B2(OH)4, and the F-containing compound is KF, NH4F, NH4HF2, KBF4, or KHF2; b. The polycrystalline powder of compound K2B2OF6 obtained in step a is placed in a platinum crucible, heated to 300-400℃, and kept at the temperature for 10-60 hours to obtain a mixed melt. The temperature is then slowly reduced to 250℃ at a rate of 0.1-2℃ / h, and then rapidly reduced to room temperature at a rate of 5-10℃ / h to obtain K2B2OF6 seed crystals. c. Fix the seed crystal obtained in step b onto the seed crystal rod, lower the seed crystal from above the mixed melt obtained in step b, apply a crystal rotation of 2-20 rpm through the crystal growth controller, and cool down at a rate of 0.1-3℃ / h. After the crystal growth stops, the K2B2OF6 nonlinear optical crystal is obtained.

3. The use of the potassium fluoroborate nonlinear optical crystal of claim 1 in the fabrication of multi-band frequency doubling devices or optical elements.

4. The use of the potassium fluoroborate nonlinear optical crystal according to claim 1 in preparing second-harmonic light output from the 1064 nm fundamental frequency light output by an Nd:YAG laser.

5. The use of the potassium fluoroborate nonlinear optical crystal according to claim 1 in the preparation of frequency multiplier generators, up or down frequency converters, or optical parametric oscillators.

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