Preparation method and use of compound rubidium potassium borophosphate and its nonlinear optical crystal

Abstract

The present application relates to a kind of compound potassium rubidium borophosphate and a kind of preparation method and purposes of potassium rubidium borophosphate nonlinear optical crystal, the chemical formula of the compound potassium rubidium borophosphate and its crystal is K 0.9 Rb 2.1 B8PO 16 Crystal belongs to monoclinic system, space group Cc, cell parameter Z=4, molecular weight is 586.16. Compound potassium rubidium borophosphate is synthesized using high-temperature solid-phase reaction method, and potassium rubidium borophosphate nonlinear optical crystal is grown using high-temperature melt method. The preparation method is simple and low in cost. The obtained crystal has a wide light transmission range, stable physical and chemical properties, and can be used to prepare nonlinear optical devices.

Description

TECHNICAL FIELD

[0001] The present application relates to a compound of the formula K 0.9 Rb 2.1 B8PO 16 The present application relates to a compound of the formula K BACKGROUND

[0002] Deep-ultraviolet lasers have high efficiency, good beam quality, long life and other advantages, and have wide applications in the fields of semiconductor lithography, precision machining and ultra-precision optoelectronic instruments. Nonlinear optical crystals are the key materials for laser frequency conversion in all-solid-state lasers. Based on the multi-stage frequency conversion technology of nonlinear optical crystals, deep-ultraviolet lasers can be obtained by taking near-infrared all-solid-state solid lasers as the fundamental light source. At present, the commonly used nonlinear optical crystals mainly include β-BaB2O4, LiB3O5, CsB3O5, CsLiB6O 10 , KBe2BO3F2, etc. However, these materials have the following shortcomings: poor shortest frequency-doubled output wavelength, low frequency conversion efficiency, easy deliquescence, serious layered growth habit, long growth cycle, etc. Therefore, high-performance nonlinear optical crystal materials have always been a research hotspot in the field of functional materials. A suitable ultraviolet or deep-ultraviolet nonlinear optical crystal must meet the following requirements: 1) non-centrosymmetric structure; 2) effective nonlinear optical coefficient is more than 1 times of KDP, i.e. d eff > d 36 (kdp) = 0.39 pm / v; 3) wide transmission range, ultraviolet cutoff edge is lower than 200 nm; 4) moderate birefringence (Δn = 0.05-0.08) to meet the phase matching conditions of ultraviolet or deep-ultraviolet harmonic generation; 5) easy to grow large-size single crystals, stable physical and chemical properties, easy to process, etc.

[0003] The multi-anion group design strategy is effective in exploring high-performance ultraviolet or deep-ultraviolet nonlinear optical crystals. Borophosphates with asymmetric [BO4] and [PO4] tetrahedra as basic structural units usually have a large band gap, but the large band gap materials often have small frequency doubling response and birefringence. However, based on the anion group theory, when the structure contains parallel arranged π-conjugated [BO3] motifs, larger frequency doubling effect and birefringence can be easily obtained. On the other hand, the introduction of non-π-conjugated [BO4] and [PO4] motifs is conducive to eliminating the dangling bonds of [BO3] motifs and obtaining a shorter cutoff edge. Therefore, the design and synthesis of borophosphates with mixed coordination groups of [BO3], [BO4] and [PO4] are considered to be potential candidate materials for exploring high-performance ultraviolet or deep-ultraviolet nonlinear optical crystals. SUMMARY

[0004] The application aims to provide a compound potassium rubidium borophosphate and a method for synthesizing the compound potassium rubidium borophosphate by using a high-temperature solid phase method. 0.9 Rb 2.1 B8PO 16 ;

[0005] The application aims to provide a potassium rubidium borophosphate nonlinear optical crystal and a preparation method for growing the potassium rubidium borophosphate nonlinear optical crystal by using a high-temperature melt method.

[0006] The application aims to provide an application of the potassium rubidium borophosphate nonlinear optical crystal, which is used for preparing a frequency doubler, a frequency converter or a nonlinear optical device such as an optical parametric oscillator.

[0007] The technical solution of the application is as follows:

[0008] The application aims to provide a compound potassium rubidium borophosphate, which is characterized by a chemical formula of K 0.9 Rb 2.1 B8PO 16 , a molecular weight of 586.16, and a preparation method for preparing the compound potassium rubidium borophosphate by using a high-temperature solid phase method according to the following chemical reaction formula.

[0009] 1) 0.9K2CO3+2.1Rb2CO3+16H3BO3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +27H2O↑+3CO2↑+2NH3↑

[0010] 2) 0.9K2CO3+2.1Rb2CO3+16H3BO3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +24H2O↑+3CO2↑

[0011] 3) 1.8KOH+4.2RbOH+16H3BO3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +27H2O↑

[0012] 4) 0.9K2O+2.1Rb2O+16H3BO3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +27H2O↑+2NH3↑

[0013] 5) 1.8KF+4.2RbF+16H3BO3+P2O5→2K 0.9 Rb2.1 B8PO 16 +21H2O↑+6HF↑

[0014] 6)1.8KCl+4.2RbCl+16H3BO3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +24H2O↑+2NH3↑+6HCl↑

[0015] 7)0.9K2CO3+2.1Rb2CO3+8B2O3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +3H2O↑+3CO2↑+2NH3↑

[0016] 8)0.9K2CO3+2.1Rb2CO3+8B2O3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +3CO2↑

[0017] 9)1.8KOH+4.2RbOH+8B2O3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +3H2O↑

[0018] 10)0.9K2O+2.1Rb2O+8B2O3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +3H2O↑+2NH3↑

[0019] 11)1.8KF+4.2RbF+8B2O3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +6HF↑+2NH3↑

[0020] 12)1.8KCl+4.2RbCl+8B2O3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +2NH3↑+6HCl↑

[0021] 13)0.9K2CO3+2RbH2PO4+1.1Rb2CO3+16H3BO3→2K 0.9 Rb 2.1 B8PO 16 +26H2O↑+2CO2↑

[0022] 14) 0.9 K2CO3 + 2 RbH2PO4 + 1.1 Rb2CO3 + 8 B2O3 → 2 K 0.9 Rb 2.1 B8PO 16 + 2 H2O↑ + 2 CO2↑

[0023] 15) 1.8 KNO3 + 4.2 RbNO3 + 16 H3BO3 + P2O5 → 2 K 0.9 Rb 2.1 B8PO 16 + 24 H2O↑ + 6 NO2↑

[0024] The second object of the present application is to provide a potassium rubidium borophosphate nonlinear optical crystal, characterized in that the crystal has a chemical formula of K 0.9 Rb 2.1 B8PO 16 , crystallized in a monoclinic system, space group Cc, with a non-centrosymmetric structure, and cell parameters of a = 0.8 nm, b = 0.8 nm, c = 1.2 nm, β = 90°, and Z = 4. The potassium rubidium borophosphate nonlinear optical crystal is grown by a high-temperature melt method, and has an ultraviolet cutoff edge less than 190 nm.

[0025] A preparation method of a potassium rubidium borophosphate nonlinear optical crystal, characterized in that the crystal is grown by a high-temperature melt method, and the specific operation is as follows:

[0026] a. mixing single-phase polycrystalline powder of the compound potassium rubidium borophosphate with a fluxing agent uniformly, heating the mixture to 650-750°C at a heating rate of 10-30°C / h, keeping the temperature constant for a period of time to obtain a mixed solution, and then cooling the solution to 550-650°C, wherein the molar ratio of the single-phase polycrystalline powder of the compound potassium rubidium borophosphate to the fluxing agent is 1:0-30.

[0027] or directly heating a mixture containing a potassium compound, a rubidium compound, a boron compound, a phosphorus compound or a mixture of a potassium compound, a rubidium compound, a boron compound, a phosphorus compound and a fluxing agent to 650-750°C at a heating rate of 10-30°C / h, keeping the temperature constant for a period of time to obtain a mixed solution, and then cooling the solution to 550-650°C, wherein the molar ratio of the potassium compound, the rubidium compound, the boron compound, the phosphorus compound to the fluxing agent is 0.6-1.2:1.8-2.4:7.7-8.3:0.7-1.3:30.

[0028] The fluxing agent includes single fluxing agent and composite fluxing agent, which respectively correspond to alkali metal salts, i.e. at least one or more of alkali metal carbonate, alkali metal nitrate, alkali metal sulfate, alkali metal oxalate, alkali metal borate, alkali metal phosphate, alkali metal halide, alkali metal fluoborate, alkali metal metaborate, and alkali metal oxide, alkali metal hydroxide, monobasic phosphate, dibasic phosphate, boron oxide, boric acid, phosphoric acid, lead oxide, lead fluoride, molybdenum oxide, bismuth oxide.

[0029] The single-phase polycrystalline powder of the compound potassium rubidium borophosphate is prepared by a high-temperature solid-phase reaction method, and the specific operation is as follows: the potassium-containing compound, the rubidium-containing compound, the boron-containing compound and the phosphorus-containing compound are uniformly mixed, wherein the molar ratio of potassium in the potassium-containing compound, rubidium in the rubidium-containing compound, boron in the boron-containing compound and phosphorus in the phosphorus-containing compound is 0.6-1.2:1.8-2.4:7.7-8.3:0.7-1.3, and then the mixture is ground and placed in a muffle furnace for calcination to remove water and gas in the raw materials. After grinding, the mixture is placed in a muffle furnace for calcination, and during the calcination, the mixture is fully ground for multiple times. After cooling to room temperature, the single-phase polycrystalline powder of the compound potassium rubidium borophosphate is obtained.

[0030] b. Preparing the seed crystal of the compound potassium rubidium borophosphate: the mixed melt obtained in step a is slowly cooled to room temperature at a cooling rate of 2-10 ℃ / h, and the potassium rubidium borophosphate seed crystal is spontaneously crystallized;

[0031] c. The crucible containing the mixed melt prepared in step a is placed in a crystal growth furnace, and the seed crystal obtained in step b is fixed on a seed crystal rod and lowered from the top of the crystal growth furnace. The seed crystal is preheated for a period of time, and then the seed crystal is lowered to contact the surface of the mixed melt or the mixed melt for remelting. After constant temperature for a period of time, the temperature is slowly lowered to the saturation point temperature.

[0032] d. The temperature is continuously lowered slowly, and the seed crystal rod is rotated for crystal growth. After the single crystal grows to the required size, the crystal is lifted away from the surface of the mixed melt, and the temperature is slowly lowered to room temperature. Then the crystal is taken out of the furnace, and the potassium rubidium borophosphate nonlinear optical crystal is obtained.

[0033] The third object of the present application is the potassium rubidium borophosphate nonlinear optical crystal, and the chemical formula of the crystal is K 0.9 Rb 2.1 B8PO 16, crystallized in monoclinic system, space group Cc. It has non-central symmetric structure, high purity of crystal product, easy growth of crystal, no inclusion in the inside, fast growth speed, short growth period, low cost, easy to obtain large size crystal and other advantages; the obtained crystal has a relatively wide light transmission waveband, high hardness, good mechanical properties, not easy to break and deliquesce, easy to process and store and other advantages. The potassium rubidium borophosphate nonlinear optical crystal obtained by the method has the advantages that according to the needs of device application, it can be used as a nonlinear optical device, which comprises the device for generating at least one output radiation with different frequency from the incident electromagnetic radiation after at least one piece of nonlinear optical device is passed through at least one incident electromagnetic radiation. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 For the compound K in the application 0.9 Rb 2.1 B8PO 16 Powder XRD spectrum.

[0035] Figure 2 For the potassium rubidium borophosphate nonlinear optical crystal K in the application 0.9 Rb 2.1 B8PO 16 Crystal structure diagram.

[0036] Figure 3 For the K in the application 0.9 Rb 2.1 B8PO 16 UV-Vis diffuse reflectance spectrum.

[0037] Figure 4 For the working principle diagram of the nonlinear optical device made by the application, wherein 1 is a laser, 2 is a lens, 3 is K 0.9 Rb 2.1 B8PO 16 Nonlinear optical crystal, 4 is a light splitting prism, and 5 is a filter. DETAILED DESCRIPTION

[0038] The application will be described in detail below in combination with the drawings and implementation examples, but is not limited to the described examples. Any improvement and change made on the basis of the application is within the protection scope of the application.

[0039] Example 1:

[0040] According to the reaction formula: 0.9K2CO3+2.1Rb2CO3+16H3BO3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +27H2O↑+3CO2↑+2NH3↑Synthesis of compound K 0.9 Rb 2.1B8PO 16 :

[0041] K2CO3, Rb2CO3, H3BO3, NH4H2PO4 were weighed according to the molar ratio of 0.9:2.1:16:2, mixed uniformly and ground thoroughly in a mortar, then loaded into a Φ60mmx60mm open platinum crucible, placed in a muffle furnace, slowly heated to 350°C, kept constant for 24 hours, cooled to room temperature, taken out, ground for the second time, then loaded into a muffle furnace, heated to 700°C again, kept constant for 24 hours, cooled to room temperature, taken out, ground for the third time, then loaded into a muffle furnace, kept constant at 700°C for 24 hours again, taken out, and the borophosphate potassium rubidium single-phase polycrystal powder was prepared by grinding. The product was analyzed by X-ray, and the obtained X-ray diffraction spectrum was consistent with the X-ray spectrum in Figure 1 attached hereto; Figure 1

[0042] The obtained borophosphate potassium rubidium K 0.9 Rb 2.1 B8PO 16 The single-phase polycrystal powder was mixed with a flux H3BO3-PbO according to the molar ratio of 1:3, wherein the molar ratio of H3BO3 to PbO was 1:5, loaded into a Φ60mmx60mm open platinum crucible, heated to 750°C at a heating rate of 20°C / h, kept constant for 10 hours, to obtain a mixed solution, and then cooled to 700°C;

[0043] Slowly cooled to room temperature at a rate of 0.5°C / h, and the borophosphate potassium rubidium seed crystal was obtained by spontaneous crystallization;

[0044] Growth of crystals in a compound melt: the obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal was fixed on a seed crystal rod, the seed crystal was preheated on the surface of the mixed melt for 10 minutes from the top of the crystal growth furnace, immersed into the liquid surface, and the seed crystal was subjected to remelting in the mixed melt, kept constant for 30 minutes, and then rapidly cooled to the saturation point temperature of 650°C;

[0045] Then, the temperature was decreased at a rate of 1°C / day, the seed crystal rod was rotated at a speed of 10 rpm, after the growth of the crystal was completed, the crystal was separated from the liquid surface, the temperature was decreased to room temperature at a rate of 10°C / h, and then the crystal was taken out from the furnace, to obtain the K 0.9 Rb 2.1 B8PO 16 crystal.

[0046] Example 2

[0047] According to the reaction formula: 1.8KOH+4.2RbOH+16H3BO3+P2O5→2K 0.9 Rb 2.1 B8PO​16 +27H2O↑synthesis of compound K 0.9 Rb 2.1 B8PO 16 ;

[0048] KOH, RbOH, H3BO3, P2O5 were weighed directly as raw materials in a molar ratio of 1.8:4.2:16:1, the raw materials were mixed with flux KOH-P2O5 in a molar ratio of 1:5, wherein the molar ratio of KOH to P2O5 was 2:3, and were loaded into a Φ60mm×60mm open platinum crucible and heated to 780℃, and kept at this temperature for 48 hours to obtain a mixed solution, and then cooled to 730℃;

[0049] Slowly cooled to room temperature at a rate of 1℃ / h, and spontaneously crystallized to obtain potassium rubidium borophosphate seed crystals;

[0050] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal was fixed on the seed crystal rod and the seed crystal was lowered from the top of the crystal growth furnace, preheated on the surface of the mixed melt for 10 minutes, immersed into the liquid surface, and allowed to remelt in the mixed melt, kept at a constant temperature for 30 minutes, and then quickly cooled to the saturation point temperature of 680℃;

[0051] Then cooled at a rate of 0.5℃ / day, rotated the seed crystal rod at a speed of 5rpm, and after the crystal growth was completed, the crystal was separated from the liquid surface, cooled to room temperature at a rate of 10℃ / h, and then the crystal was taken out of the furnace to obtain K 0.9 Rb 2.1 B8PO 16 crystal.

[0052] Example 3

[0053] According to the reaction formula: 0.9K2O+2.1Rb2O+16H3BO3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +27H2O↑+2NH3↑synthesis of compound K 0.9 Rb 2.1 B8PO 16 ;

[0054] K2O, Rb2O, H3BO3, NH4H2PO4 were weighed directly as raw materials in a molar ratio of 0.9:2.1:16:2, the raw materials were mixed with flux K2O-MoO3 in a molar ratio of 1:10, wherein the molar ratio of K2O to MoO3 was 1:2, and were loaded into a Φ60mm×60mm open platinum crucible and heated to 730℃, and kept at this temperature for 48 hours to obtain a mixed solution, and then cooled to 680℃;

[0055] Slowly cool to room temperature at a rate of 2°C / h, and obtain the potassium rubidium borophosphate seed crystal by spontaneous crystallization;

[0056] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal is fixed on the seed crystal rod and is lowered from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the mixed melt for 10 minutes, is immersed into the liquid surface, and is subjected to remelting in the mixed melt. The temperature is kept constant for 30 minutes, and is rapidly cooled to the saturation point temperature of 650°C.

[0057] Then, the temperature is cooled at a rate of 1.5°C / day, and the seed crystal rod is not rotated. After the crystal is grown to the required size, the crystal is lifted away from the liquid surface, is cooled to room temperature at a rate of 20°C / h, and is then taken out of the furnace, thereby obtaining the K 0.9 Rb 2.1 B8PO 16 crystal.

[0058] Example 4

[0059] According to the reaction formula: 1.8KF+4.2RbF+16H3BO3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +21H2O↑+6HF↑, the compound K 0.9 Rb 2.1 B8PO 16 is synthesized.

[0060] The KF, RbF, H3BO3 and P2O5 are directly weighed according to the molar ratio of 1.8:4.2:16:1. The raw materials are mixed with the flux KF-P2O5 according to the molar ratio of 1:8, wherein the molar ratio of KF to P2O5 is 3:5. The mixture is loaded into a Φ60mm×60mm open platinum crucible, is heated to 760°C, and is kept constant for 48 hours, thereby obtaining a mixed solution. Then, the temperature is cooled to 710°C.

[0061] The temperature is slowly cooled to room temperature at a rate of 3°C / h, and the potassium rubidium borophosphate seed crystal is obtained by spontaneous crystallization.

[0062] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal is fixed on the seed crystal rod and is lowered from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the mixed melt for 10 minutes, is immersed into the liquid surface, and is subjected to remelting in the mixed melt. The temperature is kept constant for 30 minutes, and is rapidly cooled to the saturation point temperature of 670°C.

[0063] K 0.9 Rb 2.1 B8PO 16 crystal.

[0064] Example 5

[0065] According to the reaction formula: 0.9K2CO3+2.1Rb2CO3+8B2O3+2NH4H2PO4→2K 0.9 Rb 2.1 B8PO 16 +3H2O↑+3CO2↑+2NH3↑, the compound K 0.9 Rb 2.1 B8PO 16 ;

[0066] K2CO3, Rb2CO3, B2O3, NH4H2PO4 are directly weighed as raw materials in a molar ratio of 0.9:2.1:8:2, and the raw materials are mixed with a flux K2CO3-PbO-B2O3 in a molar ratio of 1:15, wherein the molar ratio of K2CO3, PbO and B2O3 is 10:8:15, and then the mixture is loaded into a Φ60mm*60mm open platinum crucible and heated to 700°C, and kept at this temperature for 48 hours to obtain a mixed solution, and then the temperature is lowered to 650°C;

[0067] The temperature is slowly lowered to room temperature at a rate of 1.5°C / h, and the potassium rubidium borophosphate seed crystal is spontaneously crystallized;

[0068] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal is fixed on the seed crystal rod and lowered from the top of the crystal growth furnace, and the seed crystal is preheated on the surface of the mixed melt for 10 minutes, immersed in the liquid surface, and then the seed crystal is remelted in the mixed melt, and kept at a constant temperature for 30 minutes, and then rapidly cooled to the saturation point temperature of 670°C;

[0069] The temperature is lowered at a rate of 0.3°C / day, the seed crystal rod is rotated at a speed of 5rpm, and after the crystal growth is completed, the crystal is separated from the liquid surface, the temperature is lowered to room temperature at a rate of 5°C / h, and then the crystal is taken out of the furnace to obtain K 0.9 Rb 2.1 B8PO 16 crystal.

[0070] Example 6

[0071] According to the reaction formula: 1.8KOH+4.2RbOH+8B2O3+P2O5→2K 0.9 Rb2.1 B8PO 16 + 3H2O↑ to synthesize compound K 0.9 Rb 2.1 B8PO 16 ;

[0072] KOH, RbOH, B2O3, P2O5 were weighed directly according to the molar ratio of 1.8:4.2:8:1, the raw materials were mixed with flux KF-P2O5 according to the molar ratio of 2:7, wherein the molar ratio of KF to B2O3 was 4:5, and were loaded into a Φ60mm*60mm open platinum crucible, heated to 790℃, and kept constant for 48 hours to obtain a mixed solution, and then cooled to 730℃;

[0073] Slowly cooled to room temperature at a rate of 2.5℃ / h, and spontaneously crystallized to obtain potassium rubidium borophosphate seed crystals;

[0074] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal was fixed on the seed crystal rod and the seed crystal was lowered from the top of the crystal growth furnace, preheated on the surface of the mixed melt for 10 minutes, immersed into the liquid surface, and the seed crystal was remelted in the mixed melt, kept constant for 30 minutes, and quickly cooled to the saturation point temperature of 690℃;

[0075] Then cooled at a rate of 1℃ / day, and rotated the seed crystal rod at a speed of 10rpm, after the crystal growth was completed, the crystal was separated from the liquid surface, cooled to room temperature at a rate of 10℃ / h, and then the crystal was taken out from the furnace, to obtain K 0.9 Rb 2.1 B8PO 16 crystal.

[0076] Example 7

[0077] According to the reaction formula: 0.9K2CO3+2RbH2PO4+1.1Rb2CO3+16H3BO3→2K 0.9 Rb 2.1 B8PO 16 +26H2O↑+2CO2↑ to synthesize compound K 0.9 Rb 2.1 B8PO 16 ;

[0078] K2CO3, RbH2PO4, Rb2CO3, H3BO3 were weighed directly as raw materials in a molar ratio of 0.9:2:1.1:16, and the raw materials were mixed with the flux KF-PbO-H3BO3 in a molar ratio of 1:20, wherein the molar ratio of KF, PbO and H3BO3 was 4:5:10, and were loaded into a Φ60mm*60mm open platinum crucible and heated to 730°C, and kept at this temperature for 48 hours to obtain a mixed solution, and then the temperature was lowered to 680°C;

[0079] The temperature was slowly lowered to room temperature at a rate of 3°C / h, and the potassium rubidium borophosphate seed crystal was obtained by spontaneous crystallization;

[0080] The obtained K 0.9 Rb 2.1 B8PO 16 The seed crystal was fixed on the seed crystal rod and was lowered from the top of the crystal growth furnace, and the seed crystal was preheated on the surface of the mixed solution for 10 minutes, then was immersed into the liquid surface, and was remelted in the mixed solution, and was kept at this temperature for 30 minutes, and was quickly cooled to the saturation point temperature of 640°C;

[0081] Then the temperature was lowered at a rate of 0.7°C / day, and the seed crystal rod was rotated at a speed of 5rpm, and after the crystal growth was completed, the crystal was separated from the liquid surface, and the temperature was lowered to room temperature at a rate of 20°C / h, and then the crystal was taken out of the furnace, and the K 0.9 Rb 2.1 B8PO 16 crystal was obtained.

[0082] Example 8

[0083] According to the reaction formula: 1.8KNO3+4.2RbNO3+16H3BO3+P2O5→2K 0.9 Rb 2.1 B8PO 16 +24H2O↑+6NO2↑, the compound K 0.9 Rb 2.1 B8PO 16 was synthesized.

[0084] K2CO3, RbH2PO4, Rb2CO3, H3BO3 were weighed directly as raw materials in a molar ratio of 0.9:2:1.1:16, and the raw materials were mixed with the flux KF-H3BO3 in a molar ratio of 1:6, wherein the molar ratio of KF and H3BO3 was 1:5, and were loaded into a Φ60mm*60mm open platinum crucible and heated to 800°C, and kept at this temperature for 48 hours to obtain a mixed solution, and then the temperature was lowered to 760°C;

[0085] The temperature was slowly lowered to room temperature at a rate of 5°C / h, and the potassium rubidium borophosphate seed crystal was obtained by spontaneous crystallization;

[0086] The obtained K 0.9Rb 2.1 B8PO 16 The seed crystal is fixed on the seed crystal rod and dropped from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the mixed melt for 10 minutes, then immersed in the melt to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 30 minutes and then rapidly cooled to the saturation point temperature of 710℃.

[0087] Then, the temperature is lowered at a rate of 1℃ / day, and the seed crystal rod is rotated at a speed of 5 rpm. After crystal growth is complete, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 10℃ / h. The crystal is then removed from the furnace to obtain K. 0.9 Rb 2.1 B8PO 16 Crystal.

[0088] Example 9

[0089] The K obtained in Examples 1-8 0.9 Rb 2.1 B8PO 16 A single-crystal device is fabricated by matching nonlinear optical crystals in a matching direction, and then attached... Figure 4 As shown, the laser is positioned at location 3 and, at room temperature, is pumped by a 532 nm Nd:YAG Q-switched laser source, which is then injected into the K laser. 0.9 Rb 2.1 B8PO 16 The nonlinear optical crystal 3 generates frequency-doubled light with a wavelength of 266nm. The emitted beam 4 contains frequency-doubled light with wavelengths of 532nm and 266nm. After being filtered out by the filter 5, a laser with a wavelength of 266nm is obtained.

[0090] Example 10

[0091] The K obtained in Examples 1-8 0.9 Rb 2.1 B8PO 16 After being oriented and polished, the nonlinear optical crystal is made into a single crystal device. Using a 1064nm Nd:YAG Q-switched laser source as the pump source, it produces laser output with a wavelength shorter than 266nm.

Claims

1. A potassium rubidium borophosphate nonlinear optical crystal, characterized by The crystal has the chemical formula K 0.9 Rb 2.1 B8PO 16 , crystallized in monoclinic system, space group Cc, cell parameters Z = 4.

2. The potassium rubidium borophosphate nonlinear optical crystal of claim 1, wherein, The borophosphate rubidium potassium nonlinear optical crystal is grown by a high-temperature melt method.

3. The method of claim 2, wherein the potassium rubidium borophosphate nonlinear optical crystal is prepared by the steps of: The application relates to a high-temperature melt method for growing a potassium rubidium borophosphate nonlinear optical crystal K 0.9 Rb 21 B8PO 16 The specific operation steps are as follows: single-phase polycrystal powder of the compound potassium rubidium borophosphate or a mixture of single-phase polycrystal powder of the compound potassium rubidium borophosphate and a fluxing agent, or a mixture of a potassium-containing compound, a rubidium-containing compound, a boron-containing compound and a phosphorus-containing compound or a mixture of the potassium-containing compound, the rubidium-containing compound, the boron-containing compound, the phosphorus-containing compound and the fluxing agent is heated to 650-750 DEG C to obtain a mixed melt; then, a crucible containing the mixed melt is placed in a crystal growth furnace to be heated, and the temperature is lowered to a saturation point temperature; at this time, a seed rod is inserted into the melt, and then the seed rod is taken out of the melt before the melt solidifies, so that the potassium rubidium borophosphate nonlinear optical crystal is prepared. ​ The preparation method of the single-phase polycrystalline powder of the compound borophosphate rubidium potassium comprises the following steps: uniformly mixing a potassium-containing compound, a rubidium-containing compound, a boron-containing compound and a phosphorus-containing compound, and preparing the compound borophosphate rubidium potassium by a solid-phase reaction method, wherein the molar ratio of potassium in the potassium-containing compound, rubidium in the rubidium-containing compound, boron in the boron-containing compound and phosphorus in the phosphorus-containing compound is 0.6-1.2:1.8-2.4:7.7-8.3:0.7-1.3, and the mixture is ground and then placed in a muffle furnace for calcination, and the mixture is sufficiently ground for multiple times during the calcination to prepare the single-phase polycrystalline powder of the compound borophosphate rubidium potassium; The potassium-containing compound comprises at least one of KOH, K2O and a potassium salt, and the potassium salt comprises at least one of KF, KCl, KBr, KNO3, K2CO3, KHCO3, K2C2O4 and K2SO4; The rubidium-containing compound comprises at least one of RbOH, Rb2O and a rubidium salt, and the rubidium salt comprises at least one of RbF, RbCl, RbBr, RbNO3, Rb2CO3, RbHCO3, Rb2C2O4 and Rb2SO4; The boron-containing compound comprises at least one of B2O3, H3BO3 and a borate, and the borate comprises at least one of ABO2, ABO3, A3BO3 and A2B4O7, wherein A=K, Rb; The phosphorus-containing compound comprises at least one of P2O5, H3PO4 and a phosphate, and the phosphate comprises at least one of AH2PO4, A2HPO4, A3PO4, A2H2P2O7 and A4P2O7, wherein A=K, Rb, NH4.

4. The preparation method of the borophosphate rubidium potassium nonlinear optical crystal according to claim 3, wherein the molar ratio of the single-phase polycrystalline powder of the compound borophosphate rubidium potassium to a fluxing agent is 1:0-30; or the molar ratio of the potassium-containing compound, the rubidium-containing compound, the boron-containing compound, the phosphorus-containing compound to the fluxing agent is 0.6-1.2:1.8-2.4:7.7-8.3:0.7-1.3:30; and the fluxing agent comprises at least one or more of alkali metal carbonates, alkali metal nitrates, alkali metal sulfates, alkali metal oxalates, alkali metal borates, alkali metal phosphates, alkali metal halides, alkali metal fluoborates, alkali metal metaborates, alkali metal oxides and hydroxides, monobasic phosphates, dibasic phosphates, boron oxide, boric acid, phosphoric acid, lead oxide, lead fluoride, molybdenum oxide and bismuth oxide. The borophosphate rubidium potassium nonlinear optical crystal is used for preparing a frequency-doubling generator, a frequency converter or a nonlinear optical device of an optical parametric oscillator.

5. Use of potassium rubidium borophosphate nonlinear optical crystal according to claim 1, characterized in that, ​

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