Compound lanthanum calcium potassium borate and lanthanum calcium potassium borate birefringent optical crystal and preparation method and use thereof

Abstract

This invention provides a compound, lanthanum calcium potassium borate, and a birefringent optical crystal thereof, along with their preparation method and applications, belonging to the field of inorganic optical crystal materials technology. The compound, lanthanum calcium potassium borate, has the chemical formula KCaLa(BO3)2. The lanthanum calcium potassium borate birefringent optical crystal belongs to the orthorhombic crystal system, space group Pbca, with cell parameters a=10.2819(4) Å, b=9.0869(3) Å, c=13.3677(6) Å, α=β=γ=90°, cell volume 1248.95(8) ų, Z=8, molecular weight 335.70, and theoretically calculated birefringence Δn=0.0129@1064nm. The lanthanum calcium potassium borate crystal of this invention can be used as a birefringent crystal to manufacture refractive index modulators, phase modulators, polarization devices, etc.; it can provide a new candidate system for borate birefringent materials.

Description

Technical Field

[0001] This invention relates to the field of inorganic optical crystal materials technology, and in particular to the compounds lanthanum calcium potassium borate and lanthanum calcium potassium borate birefringent optical crystals, their preparation methods and uses. Background Technology

[0002] Birefringent optical crystals are important functional materials in optoelectronic technology, and can be used in devices such as optical isolation, beam shifting, polarization modulation, and phase modulation. Practical applications typically require crystals to have large optical anisotropy, a wide transmission range, good physicochemical stability, and easy processing properties such as cutting, polishing, and storage.

[0003] Borate crystals have attracted attention in areas such as birefringent materials, nonlinear optical materials, and ultraviolet-transmitting materials due to their rich structural types, wide transmission range, and good chemical stability. Introducing alkali metal, alkaline earth metal, and rare earth metal cations can help regulate the spatial arrangement of boron oxide elements and the anisotropy of crystal structure, thus providing possibilities for obtaining new birefringent optical crystals.

[0004] Existing birefringent crystals still suffer from problems such as harsh growth conditions, limited crystal size and processing performance, or insufficient selection of material systems. Therefore, it is necessary to provide a new lanthanum calcium potassium borate compound and its crystal, and to establish an operable solid-phase synthesis and crystal growth method. Summary of the Invention

[0005] In view of this, the present invention aims to provide a compound lanthanum calcium potassium borate and a lanthanum calcium potassium borate birefringent optical crystal, as well as their preparation method and uses.

[0006] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is a compound, lanthanum calcium potassium borate, with the chemical formula KCaLa(BO3)2.

[0007] The second technical solution of this invention is a method for preparing the compound lanthanum calcium potassium borate, comprising the following steps: Potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds are mixed, ground, pre-calcined, cooled to room temperature, ground a second time, and calcined to obtain the lanthanum calcium potassium borate.

[0008] The third technical solution of this invention is a lanthanum calcium potassium borate birefringent optical crystal with the chemical formula KCaLa(BO3)2, belonging to the orthorhombic crystal system, space group Pbca, cell parameters a=10.2819(4) Å, b=9.0869(3) Å, c=13.3677(6) Å, α=β=γ=90°, cell volume 1248.95(8) Å3, Z=8, molecular weight 335.70, and theoretically calculated birefringence Δn=0.0129@1064nm.

[0009] The fourth technical solution of this invention is a method for preparing a lanthanum calcium potassium borate birefringent optical crystal, comprising the following steps: The above compound, lanthanum calcium potassium borate, was heated and melted to obtain a molten liquid; The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt 1 for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

[0010] or, A mixture of potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds is heated and melted to obtain a molten liquid. The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

[0011] The fifth technical solution of the present invention is the application of the above-mentioned lanthanum calcium potassium borate birefringent optical crystal in the preparation of birefringent optical devices.

[0012] The present invention discloses the following technical effects: (1) The lanthanum calcium potassium borate crystal of the present invention has definite crystal structure parameters and can be used as a birefringent crystal to manufacture refractive index modulators, phase modulators, polarization devices, etc., and can provide a new candidate system for borate birefringent materials.

[0013] (2) This invention uses common inorganic raw materials and muffle furnace solid-state reaction to prepare single-phase polycrystalline powder. The process steps are clear and easy to repeat and scale up. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is the powder XRD pattern of crystal KCaLa(BO3)2 in Example 1 of this invention.

[0016] Figure 2 This is a diagram of the birefringent optical crystal structure of lanthanum calcium potassium borate of the present invention; Figure 3 The birefringence Δn of the lanthanum calcium potassium borate crystal of this invention is the calculated result. Figure 4 This is a schematic diagram illustrating the working principle of an optical device fabricated from the lanthanum calcium potassium borate birefringent optical crystal KCaLa(BO3)2 of this invention. In the diagram, 1 represents the incident light, 2 represents the polarizer, 3 represents the prism bonding joint made from a processed lanthanum calcium potassium borate birefringent optical crystal, and 4 and 5 represent two beams of light with different refractive indices, where 4 represents the extraordinary light and 5 represents the ordinary light. Detailed Implementation

[0017] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0020] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0021] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0022] The first aspect of this invention provides a compound, lanthanum calcium potassium borate, with the chemical formula KCaLa(BO3)2.

[0023] A second aspect of this invention provides a method for preparing the compound lanthanum calcium potassium borate, comprising the following steps: Potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds are mixed, ground, pre-calcined, cooled to room temperature, ground a second time, and calcined to obtain the lanthanum calcium potassium borate.

[0024] This compound can proceed according to the following balanced representative chemical reaction formula: 0.5K2CO3+CaCO3+0.5La2O3+B2O3→KCaLa(BO3)2+1.5CO2↑ 0.5K2CO3+CaCO3+0.5La2O3+2H3BO3→KCaLa(BO3)2+1.5CO2↑+3H2O↑ 2KF+2CaCO3+La2O3+4H3BO3→2KCaLa(BO3)2+2CO2↑+2HF↑+5H2O↑ 2KOH+2CaCO3+La2O3+4H3BO3→2KCaLa(BO3)2+2CO2↑+7H2O↑ 2KNO3+2CaCO3+La2O3+4H3BO3→2KCaLa(BO3)2+2CO2↑+2HNO3↑+5H2O↑ K2CO3+2CaO+La2O3+4H3BO3→2KCaLa(BO3)2+CO2↑+6H2O↑ K2CO3+2CaF2+La2O3+4H3BO3→2KCaLa(BO3)2+CO2↑+4HF↑+4H2O↑ K2CO3+2Ca(NO3)2+La2O3+4H3BO3→2KCaLa(BO3)2+CO2↑+4HNO3↑+4H2O↑ 2KF+2CaO+La2O3+4H3BO3→2KCaLa(BO3)2+2HF↑+5H2O↑ 2KF+2CaF2+La2O3+4H3BO3→2KCaLa(BO3)2+6HF↑+3H2O↑ 2KF+2Ca(NO3)2+La2O3+4H3BO3→2KCaLa(BO3)2+2HF↑+4HNO3↑+3H2O↑ 2KOH+2CaO+La2O3+4H3BO3→2KCaLa(BO3)2+7H2O↑ 2KOH+2CaF2+La2O3+4H3BO3→2KCaLa(BO3)2+4HF↑+5H2O↑ 2KOH+2Ca(NO3)2+La2O3+4H3BO3→2KCaLa(BO3)2+4HNO3↑+5H2O↑ 0.5K2CO3+CaCO3+LaF3+B2O3+1.5H2O→KCaLa(BO3)2+1.5CO2↑+3HF↑ 0.5K2CO3+CaCO3+LaF3+2H3BO3→KCaLa(BO3)2+1.5CO2↑+3HF↑+1.5H2O↑ KF+CaCO3+LaF3+2H3BO3→KCaLa(BO3)2+CO2↑+4HF↑+H2O↑ KOH+CaCO3+LaF3+2H3BO3→KCaLa(BO3)2+CO2↑+3HF↑+2H2O↑ In a preferred embodiment of the present invention, the molar ratio of potassium in the potassium-containing compound, calcium in the calcium-containing compound, lanthanum in the lanthanum-containing compound, and boron in the boron-containing compound is 0.8-1.5:0.8-1.5:0.8-1.5:1.3-2.8; the pre-calcination is performed by heating to 300-600℃ at a heating rate of 10-50℃ / h and holding at that temperature for 12-72h; the calcination is performed by heating to 300-1000℃ at a heating rate of 10-50℃ / h and holding at that temperature for 24-72h.

[0025] In this invention, the heating rate during preheating is 10-50℃ / h, for example 10℃ / h, 20℃ / h, 30℃ / h, 40℃ / h or 50℃ / h.

[0026] In this invention, the pre-firing temperature is 300-600℃, for example, 300℃, 400℃, 500℃ or 600℃.

[0027] In this invention, the heat preservation time during pre-firing is 12-72h, for example, 12h, 16h, 20h, 24h, 28h, 32h, 36h, 48h, 52h, 56h, 60h, 64h, 68h or 72h.

[0028] In this invention, the heating rate during calcination is 10-50℃ / h, for example, 10℃ / h, 20℃ / h, 30℃ / h, 40℃ / h or 50℃ / h.

[0029] In this invention, the calcination temperature is 300-1000℃, for example, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 850℃, 900℃, 950℃ or 1000℃.

[0030] In this invention, the constant temperature time during calcination is 24h, 28h, 32h, 36h, 48h, 52h, 56h, 60h, 64h, 68h or 72h.

[0031] In a preferred embodiment of the present invention, the potassium-containing compound is selected from at least one of potassium oxide, potassium hydroxide, and potassium salts; The calcium-containing compound is selected from at least one of calcium oxide, calcium hydroxide, and calcium salts; Lanthanum-containing compounds are selected from lanthanum oxide or lanthanum salts; Boron-containing compounds are selected from boron oxide, boron hydroxide, boric acid, or boron salts.

[0032] Furthermore, the potassium salt is selected from at least one of potassium fluoride, potassium carbonate, potassium hydroxide, potassium chloride, potassium bromide, potassium nitrate, potassium oxalate, and potassium sulfate; The calcium salt is selected from at least one of calcium fluoride, calcium carbonate, calcium hydroxide, calcium chloride, calcium bromide, calcium nitrate, calcium oxalate, and calcium sulfate. The lanthanum salt is selected from at least one of lanthanum chloride, lanthanum fluoride, lanthanum bromide, lanthanum nitrate, lanthanum oxalate, lanthanum carbonate, and lanthanum sulfate.

[0033] The third aspect of this invention provides a lanthanum calcium potassium borate birefringent optical crystal with the chemical formula KCaLa(BO3)2, belonging to the orthorhombic crystal system, space group Pbca, cell parameters a=10.2819(4) Å, b=9.0869(3) Å, c=13.3677(6) Å, α=β=γ=90°, cell volume 1248.95(8) Å3, Z=8, molecular weight 335.70, and theoretically calculated birefringence Δn=0.0129@1064nm.

[0034] The lanthanum calcium potassium borate birefringent optical crystal of this invention is a colorless bulk crystal with a theoretical density of 3.571 g / cm³. 3 .

[0035] The fourth aspect of this invention provides a method for preparing the above-mentioned lanthanum calcium potassium borate birefringent optical crystal.

[0036] Method 1: Includes the following steps: The compound lanthanum calcium potassium borate was heated to melt, yielding a molten liquid; The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt 1 for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

[0037] In a preferred embodiment of the present invention, the parameters for heating and melting are set as follows: heating to 400-1000℃ at a heating rate of 1-25℃ / h, and holding at that temperature for 10-60h; the holding time during remelting is 10-60min; the saturation temperature is 720-840℃; the cooling rate to the saturation temperature is 1-60℃ / min; and the cooling crystallization is performed by cooling at a rate of 0.1-5℃ / day while rotating the seed crystal rod at a speed of 0-50rpm. After the single crystal grows to the required size, crystallization is stopped, and the crystal is lifted off the surface of the melt and cooled to room temperature at a rate of 1-80℃ / h.

[0038] In this invention, the heating rate during melting is 1-25℃ / h, for example, 1℃ / h, 5℃ / h, 10℃ / h, 15℃ / h, 20℃ / h or 25℃ / h.

[0039] In this invention, the temperature during heating and melting is 400-1000℃, for example, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃.

[0040] In this invention, the constant temperature time for heating and melting is 10-60 hours, for example, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours or 60 hours.

[0041] In this invention, the constant temperature holding time during remelting is 10-60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0042] In this invention, the cooling rate during cooling crystallization is 0.1-5℃ / day, for example, 0.1℃ / day, 0.5℃ / day, 1℃ / day, 2℃ / day, 3℃ / day, 4℃ / day or 5℃ / day.

[0043] In this invention, after the crystal is removed from the surface of the melt, the cooling rate to room temperature is 1-80℃ / h, for example, 1℃ / h, 5℃ / h, 10℃ / h, 20℃ / h, 30℃ / h, 40℃ / h, 50℃ / h, 60℃ / h, 70℃ / h or 80℃ / h.

[0044] In a preferred embodiment of the present invention, when heating and melting the above-mentioned compound lanthanum calcium potassium borate, a fluxing agent is also added; the fluxing agent is a single fluxing agent or a composite fluxing agent.

[0045] Furthermore, the molar ratio of the compound lanthanum calcium potassium borate to the flux is 1:0-20, and is not 0.

[0046] Furthermore, the single flux is selected from at least one of boric acid, barium fluoride, sodium fluoride, potassium fluoride, lithium fluoride, lead fluoride, rubidium fluoride, cesium fluoride, sodium carbonate, lithium carbonate, cesium carbonate, barium carbonate, lithium metaborate, potassium metaborate, and sodium metaborate. The composite flux is selected from NaF-KF, NaF-LiF, LiF-KF, NaF-BaF2, KF-BaF2, LiF-BaF2, NaF-H3BO3, KF-H3BO3, LiF-H3BO3, BaF2-H3BO3, Na2CO3-H3BO3, K2CO3-H3BO3, Cs2CO3-H3BO3, PbO-H3BO3, BaF2-Na2CO3, NaF One or more of the following: Na₂CO₃, LiF-Na₂CO₃, KF-Na₂CO₃, PbF₂-Na₂CO₃, PbF₂-BaF₂, PbO-BaF₂, PbO-PbF₂, PbO-NaF, PbO-Na₂CO₃, PbF₂-NaF, BaF₂-NaBO₂, H₃BO₃-BaF₂-NaBO₂, H₃BO₃-BaF₂-NaF, and H₃BO₃-BaF₂-KF.

[0047] Furthermore, the molar ratio of NaF to KF in NaF-KF is 1-3:1-6; the molar ratio of NaF to LiF in NaF-LiF is 1-3:1-6; the molar ratio of LiF to KF in LiF-KF is 1-4:1-5; the molar ratio of NaF to BaF2 in NaF-BaF2 is 1-4:1-3; the molar ratio of KF to BaF2 in KF-BaF2 is 1-4:1-3; the molar ratio of LiF to BaF2 in LiF-BaF2 is 1-4:1-3; the molar ratio of NaF to H3BO3 in NaF-H3BO3 is 1-6:1-7; and the molar ratio of KF to H3BO3 in KF-H3BO3 is 1-6:1-7. 1-7; The molar ratio of LiF to H3BO3 in LiF-H3BO3 is 1-6:1-7; The molar ratio of BaF2 to boric acid in BaF2-H3BO3 is 1-6:1-7; The molar ratio of Na2CO3 to H3BO3 in Na2CO3-H3BO3 is 1-2:1-4; The molar ratio of K2CO3 to H3BO3 in K2CO3-H3BO3 is 1-2:1-4; The molar ratio of Cs2CO3 to H3BO3 in Cs2CO3-H3BO3 is 1-2:1-4; The molar ratio of PbO to H3BO3 in PbO-H3BO3 is 0.5-3:1-5; The molar ratio of BaF2 to Na2CO3 in BaF2-Na2CO3 is 0.5-3:1-5. The molar ratio of O3 is 1-5:1-3; the molar ratio of NaF to Na2CO3 in NaF-Na2CO3 is 1-5:1-3; the molar ratio of NaF to Na2CO3 in NaF-Na2CO3 is 1-5:1-3; the molar ratio of LiF to Na2CO3 in LiF-Na2CO3 is 1-5:1-3; the molar ratio of KF to Na2CO3 in KF-Na2CO3 is 1-5:1-3; the molar ratio of KF to Na2CO3 in KF-Na2CO3 is 1-5:1-3; the molar ratio of PbF2 to Na ... The molar ratio of CO3 is 1-5:1-3; the molar ratio of PbF2 to BaF2 in PbF2-BaF2 is 0.3-3:1-4; the molar ratio of PbO to BaF2 in PbO-BaF2 is 0.3-3:1-4; the molar ratio of PbO to PbF2 in PbO-PbF2 is 0.3-3:1-4; the molar ratio of PbO to NaF in PbO-NaF system is 0.3-3:1-4; the molar ratio of PbO to NaF in PbO-NaF system is 0.3-3:1-4; the molar ratio of PbO to Na2CO3 in PbO-Na2CO3 is 0.5-2:0.5-2; the molar ratio of PbF2 to NaF in PbF2-NaF is 0.The molar ratio of BaF2 to NaBO2 in the BaF2-NaBO2 system is 1:5:1:8; the molar ratio of H3BO3, BaF2, and NaBO2 in the H3BO3-BaF2-NaBO2 system is 1:5:1:3:1:8; the molar ratio of H3BO3, BaF2, and NaF in the H3BO3-BaF2-NaF system is 2:4:1:3:1:5; and the molar ratio of H3BO3, BaF2, and KF in the H3BO3-BaF2-KF system is 2:4:1:3:1:5.

[0048] Method 2: Includes the following steps: A mixture of potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds is heated and melted to obtain a molten liquid. The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

[0049] In a preferred embodiment of the present invention, the molar ratio of potassium-containing compound, calcium-containing compound, lanthanum-containing compound, and boron-containing compound is 0.8-1.5:0.8-1.5:0.8-1.5:1.3-2.8; the parameters for the heating and melting are set as follows: heating to 400-1000℃ at a heating rate of 1-25℃ / h and holding at that temperature for 10-60h; the holding time during the remelting is 10-60min; the saturation temperature is 720-840℃; the cooling rate to the saturation temperature is 1-60℃ / min; the cooling crystallization is performed by cooling at a rate of 0.1-5℃ / day while rotating the seed crystal rod at a speed of 0-50rpm, stopping crystallization after the single crystal grows to the required size, lifting the crystal off the surface of the melt, and then cooling to room temperature at a rate of 1-80℃ / h. When heating and melting a mixture of potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds, a fluxing agent is also added; the fluxing agent may be a single fluxing agent or a composite fluxing agent.

[0050] In this invention, the heating rate during melting is 1-25℃ / h, for example, 1℃ / h, 5℃ / h, 10℃ / h, 15℃ / h, 20℃ / h or 25℃ / h.

[0051] In this invention, the temperature during heating and melting is 400-1000℃, for example, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃.

[0052] In this invention, the constant temperature time for heating and melting is 10-60 hours, for example, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours or 60 hours.

[0053] In this invention, the constant temperature holding time during remelting is 10-60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0054] In this invention, the cooling rate to saturation temperature is 1-60℃ / min, for example, 1℃ / min, 5℃ / min, 10℃ / min, 20℃ / min, 30℃ / min, 40℃ / min, 50℃ / min or 60℃ / min.

[0055] In this invention, the cooling rate during cooling crystallization is 0.1-5℃ / day, for example, 0.1℃ / day, 0.5℃ / day, 1℃ / day, 2℃ / day, 3℃ / day, 4℃ / day or 5℃ / day.

[0056] In this invention, after the crystal is removed from the surface of the melt, the cooling rate to room temperature is 1-80℃ / h, for example, 1℃ / h, 5℃ / h, 10℃ / h, 20℃ / h, 30℃ / h, 40℃ / h, 50℃ / h, 60℃ / h, 70℃ / h or 80℃ / h.

[0057] Furthermore, the total molar number of the potassium-containing compound, calcium-containing compound, lanthanum-containing compound, and boron-containing compound, and the molar ratio of the flux, are 1:0-20, and not 0. The potassium-containing compound, calcium-containing compound, lanthanum-containing compound, and boron-containing compound are the same as those used in the preparation method of the aforementioned compound, lanthanum calcium potassium borate.

[0058] Furthermore, the single flux is selected from at least one of boric acid, barium fluoride, sodium fluoride, potassium fluoride, lithium fluoride, lead fluoride, rubidium fluoride, cesium fluoride, sodium carbonate, lithium carbonate, cesium carbonate, barium carbonate, lithium metaborate, potassium metaborate, and sodium metaborate. The composite flux is selected from NaF-KF, NaF-LiF, LiF-KF, NaF-BaF2, KF-BaF2, LiF-BaF2, NaF-H3BO3, KF-H3BO3, LiF-H3BO3, BaF2-H3BO3, Na2CO3-H3BO3, K2CO3-H3BO3, Cs2CO3-H3BO3, PbO-H3BO3, BaF2-Na2CO3, NaF One or more of the following: Na₂CO₃, LiF-Na₂CO₃, KF-Na₂CO₃, PbF₂-Na₂CO₃, PbF₂-BaF₂, PbO-BaF₂, PbO-PbF₂, PbO-NaF, PbO-Na₂CO₃, PbF₂-NaF, BaF₂-NaBO₂, H₃BO₃-BaF₂-NaBO₂, H₃BO₃-BaF₂-NaF, and H₃BO₃-BaF₂-KF.

[0059] Furthermore, the molar ratio of NaF to KF in NaF-KF is 1-3:1-6; the molar ratio of NaF to LiF in NaF-LiF is 1-3:1-6; the molar ratio of LiF to KF in LiF-KF is 1-4:1-5; the molar ratio of NaF to BaF2 in NaF-BaF2 is 1-4:1-3; the molar ratio of KF to BaF2 in KF-BaF2 is 1-4:1-3; the molar ratio of LiF to BaF2 in LiF-BaF2 is 1-4:1-3; the molar ratio of NaF to H3BO3 in NaF-H3BO3 is 1-6:1-7; and the molar ratio of KF to H3BO3 in KF-H3BO3 is 1-6:1-7. 1-7; The molar ratio of LiF to H3BO3 in LiF-H3BO3 is 1-6:1-7; The molar ratio of BaF2 to boric acid in BaF2-H3BO3 is 1-6:1-7; The molar ratio of Na2CO3 to H3BO3 in Na2CO3-H3BO3 is 1-2:1-4; The molar ratio of K2CO3 to H3BO3 in K2CO3-H3BO3 is 1-2:1-4; The molar ratio of Cs2CO3 to H3BO3 in Cs2CO3-H3BO3 is 1-2:1-4; The molar ratio of PbO to H3BO3 in PbO-H3BO3 is 0.5-3:1-5; The molar ratio of BaF2 to Na2CO3 in BaF2-Na2CO3 is 0.5-3:1-5. The molar ratio of O3 is 1-5:1-3; the molar ratio of NaF to Na2CO3 in NaF-Na2CO3 is 1-5:1-3; the molar ratio of NaF to Na2CO3 in NaF-Na2CO3 is 1-5:1-3; the molar ratio of LiF to Na2CO3 in LiF-Na2CO3 is 1-5:1-3; the molar ratio of KF to Na2CO3 in KF-Na2CO3 is 1-5:1-3; the molar ratio of KF to Na2CO3 in KF-Na2CO3 is 1-5:1-3; the molar ratio of PbF2 to Na ... The molar ratio of CO3 is 1-5:1-3; the molar ratio of PbF2 to BaF2 in PbF2-BaF2 is 0.3-3:1-4; the molar ratio of PbO to BaF2 in PbO-BaF2 is 0.3-3:1-4; the molar ratio of PbO to PbF2 in PbO-PbF2 is 0.3-3:1-4; the molar ratio of PbO to NaF in PbO-NaF system is 0.3-3:1-4; the molar ratio of PbO to NaF in PbO-NaF system is 0.3-3:1-4; the molar ratio of PbO to Na2CO3 in PbO-Na2CO3 is 0.5-2:0.5-2; the molar ratio of PbF2 to NaF in PbF2-NaF is 0.The molar ratio of BaF2 to NaBO2 in the BaF2-NaBO2 system is 1:5:1:8; the molar ratio of H3BO3, BaF2, and NaBO2 in the H3BO3-BaF2-NaBO2 system is 1:5:1:3:1:8; the molar ratio of H3BO3, BaF2, and NaF in the H3BO3-BaF2-NaF system is 2:4:1:3:1:5; and the molar ratio of H3BO3, BaF2, and KF in the H3BO3-BaF2-KF system is 2:4:1:3:1:5.

[0060] In this invention, the method for preparing the seed crystal of lanthanum calcium potassium borate includes the following steps: cooling the melt to room temperature at a rate of 0.5-10℃ / h, allowing it to crystallize spontaneously, and obtaining the seed crystal; Alternatively, the melt is first cooled to 900°C at a rate of 0.5-10°C / h, then cooled to 600°C at a rate of 1-15°C / h, and finally the furnace is turned off and allowed to cool naturally to room temperature, allowing spontaneous crystallization to obtain the seed crystal. The method for preparing the melt is the same as that for the melt preparation method in Method 1 or Method 2 above.

[0061] The fourth aspect of this invention provides an application of lanthanum calcium potassium borate birefringent optical crystal in the fabrication of birefringent optical devices.

[0062] In this invention, the birefringent optical device includes an optical isolator, a circulator, a beam shifter, a refractive index modulator, a phase modulator, or a polarization device.

[0063] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0064] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0065] Example 1 According to the reaction formula: 0.5K2CO3+CaCO3+0.5La2O3+2H3BO3→KCaLa(BO3)2+1.5CO2↑+3H2O↑, compound KCaLa(BO3)2 is synthesized. K₂CO₃, CaCO₃, La₂O₃, and H₃BO₃ were weighed out in a molar ratio of 0.5:1:0.5:2 and placed in a mortar. The mixture was then ground and placed into an open corundum crucible (Φ100mm×100mm). The crucible was placed in a muffle furnace and slowly heated to 400℃ at a rate of 20℃ / h, held at that temperature for 24 hours, cooled to room temperature, ground again, and then placed back into the muffle furnace. The temperature was then increased to 950℃ at a rate of 20℃ / h and held at that temperature for 24 hours. The resulting single-phase polycrystalline powder containing the calcium potassium lanthanum borate compound KCaLa(BO₃)₂ was extracted and subjected to X-ray diffraction (XRD). The obtained XRD pattern was compared with the XRD pattern obtained from the single-crystal structure of KCaLa(BO₃)₂. Figure 1 To.

[0066] The obtained KCaLa(BO3)2 single-phase polycrystalline powder was placed in an open platinum crucible with a diameter of 50 mm × 50 mm and heated to 1000 °C at a heating rate of 25 °C / h, and held at that temperature for 60 hours to obtain a melt. The solution was then cooled to 900 °C at a rate of 0.5 °C / h, and then slowly cooled to 600 °C at a rate of 1 °C / h. After the furnace was turned off, the solution was allowed to cool naturally to room temperature. Seed crystals of lanthanum calcium potassium borate KCaLa(BO3)2 were obtained by spontaneous crystallization. Crystal growth in compound melt: The obtained seed crystal is fixed on the seed crystal rod and the seed crystal is lowered from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the melt for 10 minutes and then immersed in the melt to allow the seed crystal to remelt in the melt. The temperature is kept constant for 30 minutes and then cooled to the saturation temperature of 720℃ at a rate of 10℃ / h. The temperature is then lowered at a rate of 0.1℃ / day, and the seed crystal rod is rotated at a speed of 5 rpm. After the crystal grows to the specified size, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 5℃ / hour to obtain the lanthanum calcium potassium borate birefringent optical crystal KCaLa(BO3)2.

[0067] Structural characterization: The KCaLa(BO3)2 crystal obtained in this example was characterized by XRD, and the results are as follows: Figure 1 As shown in the figure, it belongs to the orthorhombic crystal system, the space group is Pbca, the cell parameters are a=10.2819(4) Å, b=9.0869(3) Å, c=13.3677(6) Å, α=β=γ=90°, the cell volume is 1248.95(8) Å3, Z=8, and the molecular weight is 335.70.

[0068] Theoretical calculation results are as follows Figure 3 As shown, the birefringence Δn = 0.0129@1064nm.

[0069] Example 2 According to the reaction formula: 2KF + 2CaCO3 + La2O3 + 4H3BO3 → 2KCaLa(BO3)2 + 2CO2↑ + 2HF↑ + 5H2O↑, KCaLa(BO3)2 is synthesized. KF, CaCO3, La2O3, and H3BO3 were weighed directly in a molar ratio of 2:2:1:4. The weighed raw materials were mixed with flux PbO-H3BO3 in a molar ratio of 1:20, wherein the molar ratio of PbO to H3BO3 was 1:2. The mixture was placed in an open platinum crucible with a diameter of 50mm and a diameter of 50mm, and heated to 900℃ at a heating rate of 20℃ / h. The temperature was maintained for 60 hours to obtain a mixed melt. Seed crystals of KCaLa(BO3)2 were obtained by slowly cooling the temperature to room temperature at a rate of 3℃ / h. The obtained seed crystal is fixed on the seed crystal rod and lowered 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 below the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 30 minutes and then cooled to the saturation temperature of 800℃ at a rate of 10℃ / h. The temperature is then slowly reduced at a rate of 3℃ / day, and the seed crystal crucible is rotated at a speed of 10 rpm. After the crystal grows to the required size, the crystal is lifted off the surface of the melt and cooled to room temperature at a rate of 5℃ / h. Then the crystal is taken out of the furnace to obtain the lanthanum calcium potassium borate birefringent optical crystal KCaLa(BO3)2.

[0070] The KCaLa(BO3)2 crystal obtained in this example was characterized by XRD, and the results were basically consistent with those of Example 1.

[0071] Example 3 According to the reaction formula: 2KOH + 2CaCO3 + La2O3 + 4H3BO3 → 2KCaLa(BO3)2 + 2CO2↑ + 7H2O↑, KCaLa(BO3)2 is synthesized. KOH, CaCO3, La2O3, and H3BO3 were weighed directly in a molar ratio of 2:2:1:4. The weighed raw materials were mixed with flux PbO-H3BO3 in a molar ratio of 1:15, wherein the molar ratio of PbO to H3BO3 was 1:4. The mixture was placed in an open platinum crucible with a diameter of 50 mm × 50 mm and heated to 900 °C at a heating rate of 20 °C / h. The mixture was held at this temperature for 60 hours to obtain a mixed melt. Seed crystals of KCaLa(BO3)2 were obtained by slowly cooling the temperature to room temperature at a rate of 3℃ / h. The obtained seed crystal is fixed on the seed crystal rod and lowered from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the mixed melt for 15 minutes, then immersed below the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 60 minutes and then cooled to the saturation temperature of 840℃ at a rate of 10℃ / h. The temperature is then slowly reduced at a rate of 3℃ / day, and the seed crystal crucible is rotated at a speed of 10 rpm. After the crystal grows to the required size, the crystal is lifted off the surface of the melt and cooled to room temperature at a rate of 5℃ / h. Then the crystal is taken out of the furnace to obtain the lanthanum calcium potassium borate birefringent optical crystal KCaLa(BO3)2.

[0072] The KCaLa(BO3)2 crystal obtained in this example was characterized by XRD, and the results were basically consistent with those of Example 1.

[0073] Example 4 According to the reaction formula: KF + CaCO3 + LaF3 + 2H3BO3 → KCaLa(BO3)2 + CO2↑ + 4HF↑ + H2O↑, lanthanum-containing calcium borate potassium salt crystals KCaLa(BO3)2 are synthesized. KF, CaCO3, LaF3, and H3BO3 were weighed directly in a molar ratio of 1:1:1:2. The weighed raw materials were then mixed with flux KF-PbO-H3BO3 in a molar ratio of 1:10, wherein the molar ratio of KF, PbO, and H3BO3 was 1:3:5. The mixture was placed in an open platinum crucible with a diameter of 50 mm × 50 mm and heated to 950 ℃ at a heating rate of 20 ℃ / h. The mixture was held at this temperature for 60 hours to obtain a mixed melt. Seed crystals of KCaLa(BO3)2 were obtained by slowly cooling the temperature to room temperature at a rate of 3℃ / h. The obtained seed crystal is fixed on the seed crystal rod and lowered from the top of the crystal growth furnace. The seed crystal is preheated on the surface of the mixed melt for 15 minutes, then immersed below the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 60 minutes and then cooled to the saturation temperature of 840℃ at a rate of 10℃ / h. The temperature is then slowly reduced at a rate of 3℃ / day, and the seed crystal crucible is rotated at a speed of 10 rpm. After the crystal grows to the required size, the crystal is lifted off the surface of the melt and cooled to room temperature at a rate of 5℃ / h. Then the crystal is taken out of the furnace to obtain the lanthanum calcium potassium borate birefringent optical crystal KCaLa(BO3)2.

[0074] The KCaLa(BO3)2 crystal obtained in this example was characterized by XRD, and the results were basically consistent with those of Example 1.

[0075] Example 5 Using the KCaLa(BO3)2 crystal obtained in Examples 1-4 as a birefringent crystal, a single-crystal device was obtained through directional cutting and polishing. Figure 4 As shown, at position 3, incident light 1 is incident through polarizer 2 into the prism cementation 3 made of processed birefringent crystal KCaLa(BO3)2, producing two beams of light with different refractive indices: extraordinary light 4 and ordinary light 5.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A compound, lanthanum calcium potassium borate, characterized in that, The chemical formula is KCaLa(BO3)2.

2. The method for preparing the compound lanthanum calcium potassium borate as described in claim 1, characterized in that, Includes the following steps: Potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds are mixed, ground, pre-calcined, cooled to room temperature, ground a second time, and calcined to obtain the lanthanum calcium potassium borate.

3. The preparation method according to claim 2, characterized in that, The molar ratio of potassium in the potassium-containing compound, calcium in the calcium-containing compound, lanthanum in the lanthanum-containing compound, and boron in the boron-containing compound is 0.8-1.5:0.8-1.5:0.8-1.5:1.3-2.8; the pre-calcination is performed by heating to 300-600℃ at a heating rate of 10-50℃ / h and holding at that temperature for 12-72h; the calcination is performed by heating to 300-1000℃ at a heating rate of 10-50℃ / h and holding at that temperature for 24-72h.

4. A lanthanum calcium potassium borate birefringent optical crystal, characterized in that, The chemical formula is KCaLa(BO3)2, which belongs to the orthorhombic crystal system, space group is Pbca, cell parameters are a=10.2819(4) Å, b=9.0869(3) Å, c=13.3677(6) Å, α=β=γ=90°, cell volume is 1248.95(8) Å3, Z=8, molecular weight is 335.70, and theoretically calculated birefringence Δn=0.0129@1064nm.

5. The method for preparing the lanthanum calcium potassium borate birefringent optical crystal as described in claim 4, characterized in that, Includes the following steps: The compound lanthanum calcium potassium borate of claim 1 is heated and melted to obtain a molten liquid; The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt 1 for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

6. The preparation method according to claim 5, characterized in that, The parameters for heating and melting are set as follows: heating to 400-1000℃ at a heating rate of 1-25℃ / h, and holding at that temperature for 10-60h; the holding time during remelting is 10-60min; the saturation temperature is 720-840℃; the cooling rate to the saturation temperature is 1-60℃ / min; the cooling crystallization is as follows: cooling at a rate of 0.1-5℃ / day, while rotating the seed crystal rod at a speed of 0-50rpm, stopping crystallization after the single crystal grows to the required size, lifting the crystal off the surface of the melt, and cooling to room temperature at a rate of 1-80℃ / h.

7. The preparation method according to claim 5, characterized in that, When heating and melting the compound lanthanum calcium potassium borate according to claim 1, a fluxing agent is also added; the fluxing agent is a single fluxing agent or a composite fluxing agent.

8. The method for preparing the lanthanum calcium potassium borate birefringent optical crystal as described in claim 4, characterized in that, Includes the following steps: A mixture of potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds is heated and melted to obtain a molten liquid. The seed crystal of lanthanum calcium potassium borate is preheated and then immersed in the melt for remelting. It is then cooled to the saturation temperature and then cooled to crystallize, thus obtaining the lanthanum calcium potassium borate birefringent optical crystal.

9. The preparation method according to claim 8, characterized in that, The molar ratio of potassium in potassium-containing compounds, calcium in calcium-containing compounds, lanthanum in lanthanum-containing compounds, and boron in boron-containing compounds is 0.8-1.5:0.8-1.5:0.8-1.5:1.3-2.

8. The heating and melting parameters are set as follows: heating to 400-1000℃ at a heating rate of 1-25℃ / h and holding at that temperature for 10-60h; the holding time during remelting is 10-60min; the saturation temperature is 720-840℃; the cooling rate to the saturation temperature is 1-60℃ / min; the cooling crystallization is carried out by cooling at a rate of 0.1-5℃ / day while rotating the seed crystal rod at a speed of 0-50rpm. After the single crystal grows to the required size, crystallization is stopped, and the crystal is lifted off the surface of the melt and cooled to room temperature at a rate of 1-80℃ / h. When heating and melting a mixture of potassium-containing compounds, calcium-containing compounds, lanthanum-containing compounds, and boron-containing compounds, a fluxing agent is also added; the fluxing agent may be a single fluxing agent or a composite fluxing agent.

10. The application of the lanthanum calcium potassium borate birefringent optical crystal as described in claim 4 in the fabrication of birefringent optical devices.

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