Series of compounds calcium halogenoborates and nonlinear optical crystals of calcium halogenoborates, methods of preparation and uses

Abstract

The present application relates to a series of compounds calcium halogenated borate and calcium halogenated borate nonlinear optical crystal and preparation method and use, the molecular general formula of the series of compounds is Ca2B3O6X, wherein X=Cl, Br, molecular weight 244.04-288.50, the compound is synthesized using solid phase reaction method;The crystal is orthorhombic, space group Cmc 21, the cell parameter is a=15.360 (6)-15.406 (2) Å, b=22.115 (3)-22.175 (10) Å, c=7.3617 (11)-7.454 (4) Å, Z=16, V=2508.2 (6)-2538.7 (19) Å 3 , the crystal is grown using cosolvent method, the powder frequency doubling effect is about 1.5-2 times of KDP (KH2PO4), has wide light transmission waveband, the crystal preparation method is simple, and the cost is low, the prepared crystal is large in mechanical hardness, easy to cut, polishing processing and preservation, the series of calcium halogenated borate nonlinear optical crystal described in the application has the advantages of stable physical and chemical properties, moderate mechanical hardness, not easy to break, easy to cut, polishing processing and preservation and the like.

Description

Technical Field

[0001] This invention relates to a series of compounds, calcium borate halide and calcium borate halide nonlinear optical crystals, their preparation methods and uses. Background Technology

[0002] Ultraviolet nonlinear optical materials are key materials for generating coherent ultraviolet light in solid-state lasers. To obtain nonlinear optical materials with nonlinear optical properties, the commonly used international method is to introduce nonlinear optical functional units that easily cause distortion into the structure. These units mainly contain d... 0 d 10 Transition metal cation polyhedra or metal cation polyhedra containing lone pairs of electrons have electronic structures. However, these structural units often cause a redshift of the ultraviolet cutoff edge, making them unsuitable for use in the ultraviolet region. Borates, on the other hand, are characterized by their ability to transmit ultraviolet radiation. Many excellent nonlinear optical crystals have been discovered among borates, such as BBO (β-BBO), LBO (LiB3O5), CBO (CsB3O5), and CLBO (CsLiB6O5). 10 Nonlinear optical crystals include KBBF (KBe₂BO₃F₂) crystals. Although the crystal growth techniques for these materials have become increasingly mature, they still have significant drawbacks: such as hygroscopicity, long growth cycles, severe layered growth habits, and high cost. Therefore, synthesizing new nonlinear optical crystal materials remains a very important and challenging task.

[0003] When developing new ultraviolet nonlinear optical crystals, people still choose borate crystals with a wide transmission range and a high laser damage threshold. In order to further broaden the transmission range and make its ultraviolet cutoff edge reach the deep ultraviolet, cations are usually alkali metals or alkaline earth metals without dd electron transitions. Summary of the Invention

[0004] The purpose of this invention is to provide a series of compounds, calcium borate halide, with the general molecular formula Ca2B3O6X, where X = Cl and Br, and the compounds are synthesized by solid-state reaction.

[0005] Another objective of this invention is to provide a series of calcium borate halide nonlinear optical crystals, the general molecular formula of which is Ca2B3O6X, where X = Cl, Br, lacks a center of symmetry, belongs to the orthorhombic crystal system, space group Cmc21 (No. 36), and the cell parameters are: Ca2B3O6Cl: α=90, β=90, γ=90, Z=16, α=90, β=90, γ=90, Z=16,

[0006] Another objective of this invention is to provide a method for preparing a series of calcium borate halide nonlinear optical crystals.

[0007] Another object of the present invention is to provide the use of a series of calcium borate halide nonlinear optical crystals.

[0008] The present invention discloses a series of compounds, calcium borate halide, with the general molecular formula Ca2B3O6X, where X = Cl or Br, and the compounds are synthesized by solid-state reaction method.

[0009] A series of calcium borate halide nonlinear optical crystals, with the general molecular formula Ca₂B₃O₆X, where X = Cl or Br, lacking a center of symmetry, belonging to the orthorhombic crystal system, space group Cmc₂₁ (No. 36), and cell parameters: Ca₂B₃O₆Cl: α=90, β=90, γ=90, Z=16, Ca2B3O6Br: α=90, β=90, γ=90, Z=16,

[0010] The preparation method of the aforementioned series of calcium haloborate nonlinear optical crystals employs a fluxing method for crystal growth, and the specific operation is carried out according to the following steps:

[0011] a. Weigh out calcium-containing compounds (CaO, CaCO3, Ca(NO3)2, Ca(OH)2, or CaSO4), halogen-containing compounds (CaCl2 or CaBr2), and boron-containing compounds (H3BO3 or B2O3) in a mortar at a molar ratio of 3:1:6. Mix and grind the mixture thoroughly. Then, place it in a Φ100mm×100mm open corundum crucible and put it in a muffle furnace. Slowly heat the crucible to 350℃ and hold it at that temperature for 24 hours. Cool it to room temperature, remove the crucible, grind it a second time, and transfer it to a Φ350mm×3500mm quartz glass tube. Place the tube in a muffle furnace, heat it to 800℃, hold it at that temperature for 48 hours, and slowly cool it to room temperature. Remove the tube and grind it to obtain calcium borate chloride or calcium borate bromide single-phase polycrystalline powder. Then, perform X-ray analysis on the product. The obtained X-ray spectrum is consistent with the X-ray spectrum obtained from a series of calcium borate halide single-crystal structures.

[0012] b. With a molar ratio of 1:1-3, the calcium borate compound or calcium borate polycrystalline powder obtained in step a is mixed evenly with CaF2, LiF, KF2, LiF-H3BO3, LiF-KF-H3BO3 or LiF-KF2 as a co-solvent. The mixture is heated to 700-800℃ at a heating rate of 1-30℃ / h, held at the temperature for 15-60 hours, and then cooled to 550-650℃ to obtain a mixed melt.

[0013] Alternatively, calcium-containing compounds such as CaCO3, Ca(NO3)2, or Ca(OH)2; halogen-containing compounds such as CaX2, where X = Cl or Br; and boron-containing compounds such as H3BO3 or B2O3, are mixed with cosolvents such as CaF2, LiF, KF2, LiF-H3BO3, LiF-KF-H3BO3, or LiF-KF2 in a molar ratio of 3:1:6:1-3. The mixture is heated to 650-800℃ at a heating rate of 1-30℃ / h, held at that temperature for 15-60 hours, and then cooled to 620-700℃ to obtain a mixed melt.

[0014] c. Preparation of calcium borate halide seed crystals: The mixed melt obtained in step b is slowly cooled to room temperature at a rate of 0.5-10℃ / h to spontaneously crystallize and obtain calcium borate halide seed crystals.

[0015] d. Fix the seed crystal obtained in step c onto the seed crystal rod, lower the seed crystal from the top of the crystal growth furnace, preheat the seed crystal for 5-60 minutes, lower the seed crystal to the surface of the mixed melt or into the mixed melt for remelting, keep the temperature constant for 5-60 minutes, and lower the temperature to 620-700℃ at a rate of 1-60℃ / h.

[0016] e. Then, slowly cool down at a rate of 0.1-3℃ / day, and rotate the seed crystal rod at a speed of 1-60 rpm to grow the crystal. After the single crystal grows to the required size, lift the crystal off the surface of the mixed melt and cool it down to room temperature at a rate of 10-80℃ / h. Then take the crystal out of the furnace to obtain the calcium borate halide nonlinear optical crystal.

[0017] In the preparation method of the calcium borate halide nonlinear optical crystal, in step b, the molar ratio of LiF to H3BO3 in the co-solvent LiF-H3BO3 system is 1:1-3; the molar ratio of LiF to PbF2 in the LiF-PbF2 system is 2-3:1; and the molar ratio of LiF, NaF, and H3BO3 in the LiF-NaF-H3BO3 system is 1-3:1-3:1.

[0018] The use of the calcium borate halide nonlinear optical crystal in the fabrication of frequency multiplier generators, up-frequency converters, down-frequency converters, or optical parametric oscillators.

[0019] The present invention describes a series of calcium borate halides and calcium borate nonlinear optical crystals, their preparation methods, and applications. The series of calcium borate halides have the general molecular formula Ca₂B₃O₆X, where X = Cl, Br. These calcium borate halides are prepared using a solid-state reaction method according to the following chemical reaction formulas:

[0020] (1)3CaO+CaCl2+6H3BO3→2Ca2B3O6Cl+9H2O↑;

[0021] (2)3CaO+CaBr2+6H3BO3→2Ca2B3O6Br+9H2O↑;

[0022] (3)3CaO+CaCl2+3B2O3→2Ca2B3O6Cl;

[0023] (4)3CaO+CaBr2+3B2O3→2Ca2B3O6Br;

[0024] (5) 3CaCO3 + CaCl2 + 6H3BO3 → 2Ca2B3O6Cl + 3CO2↑ + 9H2O↑;

[0025] (6)3CaCO3+CaBr2+6H3BO3→2Ca2B3O6Br+3CO2↑+9H2O↑;

[0026] (7)3CaCO3+CaCl2+3B2O3→2Ca2B3O6Cl+3CO2↑;

[0027] (8)3CaCO3+CaBr2+3B2O3→2Ca2B3O6Cl+3CO2↑;

[0028] (9)3Ca(NO3)2+CaCl2+6H3BO3→2Ca2B3O6Cl+6NO2↑+9H2O↑;

[0029] (10)3Ca(NO3)2+CaBr2+6H3BO3→2Ca2B3O6Br+6NO2↑+9H2O↑;

[0030] (11)3Ca(NO3)2+CaCl2+3B2O3→2Ca2B3O6Cl+6NO2↑;

[0031] (12)3Ca(NO3)2+CaBr2+3B2O3→2Ca2B3O6Br+6NO2↑;

[0032] (13)3Ca(OH)2+CaCl2+6H3BO3→2Ca2B3O6Cl+12H2O↑;

[0033] (14)3Ca(OH)2+CaBr2+6H3BO3→2Ca2B3O6Br+12H2O↑;

[0034] (15)3Ca(OH)2+CaCl2+3B2O3→2Ca2B3O6Cl+3H2O↑;

[0035] (16)3Ca(OH)2+CaBr2+3B2O3→2Ca2B3O6Br+3H2O↑;

[0036] (17)3CaSO4+CaCl2+6H3BO3→2Ca2B3O6Cl+3SO3↑+9H2O↑;

[0037] (18)3CaSO4+CaBr2+3B2O3→2Ca2B3O6Br+3SO3↑+9H2O↑;

[0038] (19)3CaSO4+CaCl2+3B2O3→2Ca2B3O6Cl+3SO3↑;

[0039] (20)3CaSO4+CaBr2+3B2O3→2Ca2B3O6Br+3SO3↑.

[0040] This invention relates to a series of calcium borate halide compounds and calcium borate halide nonlinear optical crystals, their preparation methods, and applications. The obtained crystals possess advantages such as a wide transmission band, high hardness, good mechanical properties, resistance to breakage and deliquescence, and ease of processing and storage. Nonlinear optical devices fabricated using the calcium borate halide nonlinear optical crystals obtained by the method described in this invention, at room temperature, using an Nd:YAG Q-switched laser as the light source, with an incident infrared wavelength of 1064 nm, output green laser light with a wavelength of 532 nm, and the laser intensity is equivalent to 1.5-2 times that of KDP (KH₂PO₄). Attached Figure Description

[0041] Figure 1 The experimental powder X-ray diffraction pattern of this invention;

[0042] Figure 2 The crystal structure of Ca2B3O6X (X=Cl,Br) of this invention is shown.

[0043] Figure 3 The working principle diagram of the nonlinear optical device fabricated for this invention includes (1) a laser, (2) a full-focus lens, (3) a Ca2B3O6X (X=Cl,Br) nonlinear optical crystal, (4) a beam splitter, and (5) a filter. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0045] Example 1

[0046] According to the reaction formula: 3CaO + CaCl2 + 6H3BO3 → 2Ca2B3O6Cl + 9H2O↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0047] a. CaCO3, CaCl2, and H3BO3 were mixed and ground in a mortar in a molar ratio of 3:1:6. The mixture was then placed in an open corundum crucible with a diameter of 100 mm × 100 mm and placed in a muffle furnace. The temperature was slowly raised to 350 °C and held for 24 hours. After cooling to room temperature, the mixture was removed, ground a second time, and then transferred to a quartz glass tube with a diameter of 350 mm × 3500 mm. The tube was placed in a muffle furnace and heated to 800 °C. The temperature was held for 48 hours and then slowly cooled to room temperature. The mixture was then ground to obtain a single-phase polycrystalline powder of calcium borate chloride. X-ray analysis of the product showed that the obtained X-ray spectrum was consistent with the X-ray spectra obtained from a series of single-crystal structures of calcium borate halide.

[0048] b. Mix the calcium borate polycrystalline powder obtained in step a with the co-solvent CaF2 at a molar ratio of 1:5, heat it to 700℃ at a heating rate of 1℃ / h, keep it at the temperature for 15 hours, and then lower it to 600℃ to obtain a mixed melt.

[0049] c. Preparation of Ca2B3O6Cl seed crystals: The mixed melt obtained in step b is slowly cooled to room temperature at a rate of 10℃ / h, and Ca2B3O6Cl seed crystals are obtained by spontaneous crystallization.

[0050] d. Crystal growth in mixed melt: The Ca2B3O6Cl2 seed crystal obtained in step c 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 mixed melt for 60 minutes, then immersed in the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 60 minutes and then reduced to 650℃ at a rate of 60℃ / h.

[0051] e. Then, cool down at a rate of 3℃ / day, rotate the seed crystal rod at a speed of 60rpm, and after the crystal growth is completed, remove the crystal from the liquid surface and cool it down to room temperature at a rate of 80℃ / hour to obtain a Ca2B3O6Cl nonlinear optical crystal with a size of 10mm×8mm×8mm.

[0052] In the reaction formula, the raw material calcium oxide can be replaced by calcium carbonate, calcium nitrate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0053] Example 2

[0054] According to the reaction formula: 3CaO + CaBr2 + 6H3BO3 → 2Ca2B3O6Br + 9H2O↑, Ca2B3O6Br nonlinear optical crystals are prepared.

[0055] a. CaCO3, CaBr2, and H3BO3 were placed in a mortar in a molar ratio of 3:1:6, mixed, and ground carefully. The mixture was then placed in an open corundum crucible with a diameter of 100 mm × 100 mm and placed in a muffle furnace. The temperature was slowly raised to 350 °C and held for 24 hours. After cooling to room temperature, the mixture was removed, ground a second time, and then transferred to a quartz glass tube with a diameter of 350 mm × 3500 mm. The tube was placed in a muffle furnace and heated to 800 °C and held for 48 hours. After slowly cooling to room temperature, the mixture was removed and ground to obtain a single-phase polycrystalline powder of calcium borate chloride. X-ray analysis of the product showed that the obtained X-ray spectrum was consistent with the X-ray spectra obtained from a series of single-crystal structures of calcium borate halide.

[0056] b. The synthesized calcium borate bromide (Ca2B3O6Br) polycrystalline powder was mixed with the flux CaF2 at a molar ratio of 1:3 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 800 °C at a heating rate of 15 °C / h, held at the temperature for 70 hours, and then cooled to 750 °C to obtain a mixed melt.

[0057] c. Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 8℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization.

[0058] d. Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 50 minutes, then immersed in the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 50 minutes and then reduced to 700℃ at a rate of 45℃ / h.

[0059] e. Then, cool down at a rate of 2℃ / day, rotate the seed crystal rod at a speed of 50 rpm, and after the crystal growth is completed, remove the crystal from the liquid surface and cool it down to room temperature at a rate of 70℃ / hour to obtain a Ca2B3O6Br crystal with a size of 14mm×12mm×7mm.

[0060] In the reaction formula, the raw material calcium oxide can be replaced by calcium carbonate, calcium nitrate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0061] Example 3

[0062] According to the reaction formula: 3CaO + CaCl2 + 3B2O3 → 2Ca2B3O6Cl, Ca2B3O6Cl nonlinear optical crystals are prepared.

[0063] The preparation of single-phase polycrystalline powder of Ca2B3O6Cl compound was carried out according to Example 1:

[0064] The synthesized calcium borate polycrystalline powder (Ca2B3O6Cl) was mixed with the fluxing agent LiF2 at a molar ratio of 1:4 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 780 °C at a heating rate of 15 °C / h, held at that temperature for 5 hours, and then cooled to 750 °C to obtain a mixed melt.

[0065] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 1℃ / h, and Ca2B3O6Cl seed crystals were obtained by spontaneous crystallization.

[0066] Crystal growth in mixed melt: The obtained Ca2B3O6Cl 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 mixed melt for 5 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 5 minutes and then reduced to 700℃ at a rate of 1℃ / h.

[0067] The temperature is then reduced at a rate of 0.1℃ / day, and the seed crystal rod is rotated at a speed of 1 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and the temperature is reduced to room temperature at a rate of 10℃ / hour, thus obtaining a Ca2B3O6Cl crystal with a size of 10mm×11mm×7mm.

[0068] In the reaction formula, the raw material calcium oxide can be replaced by calcium carbonate, calcium nitrate, calcium hydroxide, or calcium sulfate; boron oxide can be replaced by boric acid.

[0069] Example 4

[0070] According to the reaction formula: 3CaO + CaBr2 + 3B2O3 → 2Ca2B3O6Br, Ca2B3O6Br nonlinear optical crystals are prepared.

[0071] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0072] The synthesized calcium borate bromide (Ca2B3O6Br) polycrystalline powder was mixed with the co-solvent LiF2 at a molar ratio of 1:5 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 770 °C at a heating rate of 15 °C / h, held at that temperature for 5 hours, and then cooled to 730 °C to obtain a mixed melt.

[0073] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 5℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization.

[0074] Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 5 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 5 minutes and then reduced to 670℃ at a rate of 1℃ / h.

[0075] The temperature is then reduced at a rate of 0.1℃ / day, and the seed crystal rod is rotated at a speed of 1 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 10℃ / hour, thus obtaining a Ca2B3O6Br crystal with a size of 11mm×8mm×9mm.

[0076] In the reaction formula, the raw material calcium oxide can be replaced by calcium carbonate, calcium nitrate, calcium hydroxide, or calcium sulfate; boron oxide can be replaced by boric acid.

[0077] Example 5

[0078] According to the reaction formula: 3CaCO3 + CaCl2 + 6H3BO3 → 2Ca2B3O6Cl + 3CO2↑ + 9H2O↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0079] The preparation of single-phase polycrystalline powder of Ca2B3O6Cl compound was carried out according to Example 1:

[0080] The synthesized calcium borate Ca2B3O6Cl compound polycrystalline powder was mixed with the flux KF at a molar ratio of 1:3 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 750 °C at a heating rate of 1 °C / h, held at the temperature for 25 hours, and then cooled to 700 °C to obtain a mixed melt.

[0081] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 0.5℃ / h, and calcium borate seed crystals were obtained by spontaneous crystallization.

[0082] Crystal growth in mixed melt: The obtained Ca2B3O6Cl 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 mixed melt for 25 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 25 minutes and then reduced to 670℃ at a rate of 15℃ / h.

[0083] The temperature is then reduced at a rate of 0.8℃ / day, and the seed crystal rod is rotated at a speed of 15 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 80℃ / hour, thus obtaining a Ca2B3O6Cl crystal with a size of 12mm×8mm×14mm.

[0084] In the reaction equation, the raw material calcium carbonate can be replaced by calcium oxide, calcium nitrate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0085] Example 6

[0086] According to the reaction formula: 3CaCO3 + CaBr2 + 6H3BO3 → 2Ca2B3O6Br + 3CO2↑ + 9H2O↑, Ca2B3O6Br nonlinear optical crystal is prepared.

[0087] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0088] The synthesized calcium borate bromide (Ca2B3O6Br) polycrystalline powder was mixed with the flux KF at a molar ratio of 1:4 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 780 °C at a heating rate of 1 °C / h, held at that temperature for 30 hours, and then cooled to 740 °C to obtain a mixed melt.

[0089] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 2℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization.

[0090] Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 15 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 15 minutes and then reduced to 700℃ at a rate of 60℃ / h.

[0091] The temperature is then reduced at a rate of 3℃ / day, and the seed crystal rod is rotated at a speed of 5 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 50℃ / hour, thus obtaining a Ca2B3O6Br crystal with a size of 14mm×11mm×7mm.

[0092] In the reaction equation, the raw material calcium carbonate can be replaced by calcium oxide, calcium nitrate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0093] Example 7

[0094] According to the reaction formula: 3CaCO3 + CaCl2 + 3B2O3 → 2Ca2B3O6Cl + 3CO2↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0095] The preparation of single-phase polycrystalline powder of Ca2B3O6Cl compound was carried out according to Example 1:

[0096] The synthesized Ca2B3O6Cl compound polycrystalline powder was mixed with the fluxing agent LiF-H3BO3 in a molar ratio of 1:3:1 and placed in an open platinum crucible with a diameter of 100mm×100mm. The mixture was heated to 800℃ at a heating rate of 1℃ / h, held at that temperature for 40 hours, and then cooled to 750℃ to obtain a mixed melt.

[0097] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 15℃ / h, and calcium borate seed crystals were obtained by spontaneous crystallization.

[0098] Crystal growth in mixed melt: The obtained Ca2B3O6Cl 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 mixed melt for 35 minutes and then immersed in the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 70 minutes and then reduced to 720℃ at a rate of 25℃ / h.

[0099] The temperature is then lowered at a rate of 3℃ / day, and the seed crystal rod is rotated at a speed of 15 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 40℃ / hour, thus obtaining a Ca2B3O6Cl crystal with a size of 13mm×16mm×11mm.

[0100] In the reaction equation, the raw material calcium carbonate can be replaced by calcium oxide, calcium nitrate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0101] Example 8

[0102] According to the reaction formula: 3CaCO3 + CaBr2 + 3B2O3 → 2Ca2B3O6Br + 3CO2↑, Ca2B3O6Br nonlinear optical crystal is prepared.

[0103] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0104] The synthesized calcium borate (Ca2B3O6Br) polycrystalline powder was mixed with the flux LiF-H3BO3 in a molar ratio of 1:3:1 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 830 °C at a heating rate of 1 °C / h, held at that temperature for 40 hours, and then cooled to 770 °C to obtain a mixed melt.

[0105] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 20℃ / h, and calcium borate bromide seed crystals were obtained by spontaneous crystallization.

[0106] Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 40 minutes and then immersed in the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 55 minutes and then reduced to 710℃ at a rate of 10℃ / h.

[0107] The temperature is then lowered at a rate of 4℃ / day, and the seed crystal rod is rotated at a speed of 25 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 30℃ / hour, thus obtaining a Ca2B3O6Br crystal with a size of 10mm×7mm×7mm.

[0108] In the reaction equation, the raw material calcium carbonate can be replaced by calcium oxide, calcium nitrate, calcium hydroxide, or calcium sulfate; boron oxide can be replaced by boric acid.

[0109] Example 9

[0110] According to the reaction formula: 3Ca(NO3)2 + CaCl2 + 6H3BO3 → 2Ca2B3O6Cl + 6NO2↑ + 9H2O↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0111] The preparation of Ca2B3O6Cl calcium compound single-phase polycrystalline powder was carried out according to Example 1:

[0112] The synthesized calcium borate Ca2B3O6Cl compound polycrystalline powder was mixed with the flux LiF-KF-H3BO3 in a molar ratio of 1:2:1:1, and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 820 °C at a heating rate of 15 °C / h, held at that temperature for 40 hours, and then cooled to 780 °C to obtain a mixed melt.

[0113] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 20℃ / h, and calcium borate seed crystals were obtained by spontaneous crystallization.

[0114] Crystal growth in mixed melt: The obtained Ca2B3O6Cl 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 mixed melt for 45 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 45 minutes and then reduced to 750℃ at a rate of 12℃ / h.

[0115] The temperature is then lowered at a rate of 4℃ / day, and the seed crystal rod is rotated at a speed of 28 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 38℃ / hour, thus obtaining a Ca2B3O6Cl crystal with a size of 10mm×7mm×8mm.

[0116] The calcium nitrate raw material in the reaction formula can be replaced by calcium oxide, calcium carbonate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0117] Example 10

[0118] According to the reaction formula: 3Ca(NO3)2 + CaBr2 + 6H3BO3 → 2Ca2B3O6Br + 6NO2↑ + 9H2O↑, Ca2B3O6Br nonlinear optical crystal is prepared.

[0119] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0120] The synthesized calcium borate (Ca2B3O6Br) polycrystalline powder was mixed with the flux LiF-KF-H3BO3 in a molar ratio of 1:2:1:3 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 760 °C at a heating rate of 25 °C / h, held at that temperature for 45 hours, and then cooled to 720 °C to obtain a mixed melt.

[0121] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 25℃ / h, and calcium borate bromide seed crystals were obtained by spontaneous crystallization.

[0122] Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 5 minutes and then immersed in the liquid surface to allow the seed crystal to remelt in the mixed melt. The temperature is kept constant for 15 minutes and then reduced to 650℃ at a rate of 30℃ / h.

[0123] The temperature is then lowered at a rate of 5℃ / day, and the seed crystal rod is rotated at a speed of 25 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 40℃ / hour to obtain a Ca2B3O6Br crystal with a size of 14mm×12mm×10mm.

[0124] The calcium nitrate raw material in the reaction formula can be replaced by calcium oxide, calcium carbonate, calcium hydroxide, or calcium sulfate; boric acid can be replaced by boron oxide.

[0125] Example 11

[0126] According to the reaction formula: 3Ca(NO3)2 + CaCl2 + 3B2O3 → 2Ca2B3O6Cl + 6NO2↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0127] The preparation of single-phase polycrystalline powder of Ca2B3O6Cl compound was carried out according to Example 1:

[0128] The synthesized calcium borate Ca2B3O6Cl compound polycrystalline powder was mixed with the flux LiF-KF2 in a molar ratio of 1:2:1 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 830 °C at a heating rate of 25 °C / h, held at that temperature for 45 hours, and then cooled to 800 °C to obtain a mixed melt.

[0129] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 25℃ / h, and calcium borate seed crystals were obtained by spontaneous crystallization.

[0130] Crystal growth in mixed melt: The obtained Ca2B3O6Cl 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 mixed melt for 25 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 35 minutes and then reduced to 760℃ at a rate of 40℃ / h.

[0131] The temperature is then lowered at a rate of 5℃ / day, and the seed crystal rod is rotated at a speed of 25 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 40℃ / hour, thus obtaining a Ca2B3O6Cl crystal with a size of 25mm×17mm×9mm.

[0132] In the reaction formula, the raw material calcium nitrate can be replaced by calcium carbonate, calcium hydroxide, or calcium oxalate; boric acid can be replaced by boron oxide.

[0133] Example 12

[0134] According to the reaction formula: 3Ca(NO3)2 + CaBr2 + 3B2O3 → 2Ca2B3O6Br + 6NO2↑, Ca2B3O6Br nonlinear optical crystal is synthesized.

[0135] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0136] The synthesized calcium borate bromide (Ca2B3O6Br2) polycrystalline powder was mixed with the flux LiF-KF2 in a molar ratio of 1:1:3 and placed in an open platinum crucible with a diameter of 100 mm × 100 mm. The mixture was heated to 1000 °C at a heating rate of 25 °C / h, held at that temperature for 25 hours, and then cooled to 790 °C to obtain a mixed melt.

[0137] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 15℃ / h, and calcium borate bromide seed crystals were obtained by spontaneous crystallization.

[0138] Crystal growth in mixed melt: The obtained Ca2B3O6Br 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 mixed melt for 25 minutes, then immersed in the liquid surface, so that the seed crystal is remelted in the mixed melt. The temperature is kept constant for 25 minutes and then reduced to 700℃ at a rate of 45℃ / h.

[0139] The temperature is then lowered at a rate of 3.5℃ / day, and the seed crystal rod is rotated at a speed of 60 rpm. After the crystal growth is completed, the crystal is removed from the liquid surface and cooled to room temperature at a rate of 40℃ / hour to obtain a Ca2B3O6Br crystal with a size of 24mm×18mm×13mm.

[0140] In the reaction equation, the raw material calcium nitrate can be replaced by calcium carbonate, calcium hydroxide, or calcium oxalate; boron oxide can be replaced by boric acid.

[0141] Example 13

[0142] According to the reaction formula: 3Ca(OH)₂ + CaCl₂ + 6H₃BO₃ → 2Ca₂B₃O₆Cl + 12H₂O↑, Ca₂B₃O₆Cl nonlinear optical crystal is prepared.

[0143] The preparation of single-phase polycrystalline powder of Ca2B3O6Cl compound was carried out according to Example 1:

[0144] The synthesized calcium borate Ca2B3O6Cl compound polycrystalline powder was mixed with the co-solvent LiF-KF2 in a molar ratio of 1:2:1, heated to 770℃ at a heating rate of 1℃ / h, held at the temperature for 5 hours, and then cooled to 720℃ to obtain a mixed melt.

[0145] Preparation of Ca2B3O6Cl seed crystals: The mixed melt obtained in step b was slowly cooled to room temperature at a rate of 1.5℃ / h, and Ca2B3O6Cl seed crystals were obtained by spontaneous crystallization.

[0146] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 5 minutes, the seed crystal is lowered to the surface of the mixed melt for remelting, the temperature is kept constant for 5 minutes, and the temperature is reduced to 680℃ at a rate of 1℃ / h.

[0147] The temperature is then slowly reduced at a rate of 0.1℃ / day, and the seed crystal rod is rotated at a speed of 1 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 10℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Cl nonlinear optical crystal with a size of 12mm×13mm×11mm.

[0148] Example 14

[0149] According to the reaction formula: 3Ca(OH)₂ + CaBr₂ + 6H₃BO₃ → 2Ca₂B₃O₆Br + 12H₂O↑, Ca₂B₃O₆Br nonlinear optical crystals are prepared.

[0150] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0151] The synthesized calcium borate bromide (Ca2B3O6Br) polycrystalline powder was mixed with the co-solvent LiF-KF2 in a molar ratio of 1:2:2, heated to 720℃ at a heating rate of 10℃ / h, held at that temperature for 50 hours, and then cooled to 660℃ to obtain a mixed melt.

[0152] Preparation of Ca2B3O6Br seed crystals: The mixed melt obtained in step b was slowly cooled to room temperature at a rate of 4℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization.

[0153] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 20 minutes, the seed crystal is lowered into the mixed melt for remelting, the temperature is kept constant for 50 minutes, and the temperature is reduced to 640℃ at a rate of 10℃ / h.

[0154] The temperature is then slowly reduced at a rate of 1℃ / day, and the seed crystal rod is rotated at a speed of 13 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 20℃ / h. Then the crystal is taken out of the furnace to obtain a calcium borate nonlinear optical crystal with a size of 11mm×13mm×9mm.

[0155] Example 15

[0156] According to the reaction formula: 3Ca(OH)₂ + CaCl₂ + 3B₂O₃ → 2Ca₂B₃O₆Cl + 3H₂O↑, Ca₂B₃O₆Cl nonlinear optical crystal is prepared.

[0157] Ca(OH)2, CaCl2, B2O3 and LiF-H3BO3 as a co-solvent were directly mixed uniformly in a molar ratio of 1:2:2:3, wherein the molar ratio of LiF to H3BO3 in the LiF-H3BO3 system was 1:1. The mixture was heated to 800℃ at a heating rate of 15℃ / h, held at that temperature for 50 hours, and then cooled to 700℃ to obtain a mixed melt.

[0158] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 5℃ / h, and Ca2B3O6Cl seed crystals were obtained by spontaneous crystallization.

[0159] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 15 minutes, the seed crystal is lowered to the surface of the mixed melt for remelting, the temperature is kept constant for 25 minutes, and the temperature is reduced to 680℃ at a rate of 20℃ / h.

[0160] The temperature is then slowly reduced at a rate of 0.5℃ / day, and the seed crystal rod is rotated at a speed of 60 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 80℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Cl nonlinear optical crystal with a size of 25mm×20mm×10mm.

[0161] Example 16

[0162] According to the reaction formula: 3Ca(OH)₂ + CaBr₂ + 3B₂O₃ → 2Ca₂B₃O₆Br + 3H₂O↑, Ca₂B₃O₆Br nonlinear optical crystal is prepared.

[0163] The preparation of single-phase polycrystalline powder of Ca2B3O6Br compound was carried out according to Example 2:

[0164] The synthesized calcium borate (Ca2B3O6Br) polycrystalline powder was mixed with the flux LiF-KF2-H3BO3 in a molar ratio of 1:2, wherein the molar ratio of LiF, KF and H3BO3 in the LiF-KF-H3BO3 system was 2:1:1. The mixture was heated to 780℃ at a heating rate of 25℃ / h, held at that temperature for 45 hours, and then cooled to 700℃ to obtain a mixed melt.

[0165] Preparation of calcium borate bromide seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 5℃ / h, and calcium borate bromide seed crystals were obtained by spontaneous crystallization.

[0166] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 60 minutes, the seed crystal is lowered into the mixed melt for remelting, the temperature is kept constant for 50 minutes, and the temperature is reduced to 640℃ at a rate of 30℃ / h.

[0167] The temperature is then slowly reduced at a rate of 3℃ / day, and the seed crystal rod is rotated at a speed of 60 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 80℃ / h. Then the crystal is taken out of the furnace to obtain a calcium borate nonlinear optical crystal with a size of 16mm×17mm×9mm.

[0168] Example 17

[0169] According to the reaction formula: 3CaSO4 + CaCl2 + 6H3BO3 → 2Ca2B3O6Cl + 3SO3↑ + 9H2O↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0170] CaSO4, CaCl2, H3BO3 and LiF-KF2 as a co-solvent were directly mixed in a molar ratio of 3:1:6:1, wherein the molar ratio of LiF to KF2 in the LiF-KF2 system was 2:1. The mixture was heated to 820℃ at a heating rate of 20℃ / h, held at that temperature for 60 hours, and then cooled to 690℃ to obtain a mixed melt.

[0171] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 8℃ / h, and Ca2B3O6Cl seed crystals were obtained by spontaneous crystallization.

[0172] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 50 minutes, the seed crystal is lowered into the mixed melt for remelting, the temperature is kept constant for 50 minutes, and the temperature is reduced to 630℃ at a rate of 30℃ / h.

[0173] The temperature is then slowly reduced at a rate of 1.5℃ / day, and the seed crystal rod is rotated at a speed of 20 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 50℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Cl nonlinear optical crystal with a size of 21mm×10mm×6mm.

[0174] Example 18

[0175] According to the reaction formula: 3CaSO4 + CaBr2 + 6H3BO3 → 2Ca2B3O6Br + 3SO3↑ + 9H2O↑, Ca2B3O6Br nonlinear optical crystal is prepared.

[0176] CaSO4, CaBr2, H3BO3 and LiF-KF2 as a co-solvent were directly mixed in a molar ratio of 3:1:6:1, wherein the molar ratio of LiF to H3BO3 in the LiF-KF2 system was 1:3. The mixture was heated to 780℃ at a heating rate of 25℃ / h, held at that temperature for 40 hours, and then cooled to 680℃ to obtain a mixed melt.

[0177] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 5℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization.

[0178] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 35 minutes, the seed crystal is lowered into the mixed melt for remelting, the temperature is kept constant for 25 minutes, and the temperature is reduced to 650℃ at a rate of 30℃ / h.

[0179] The temperature is then slowly reduced at a rate of 2℃ / day, and the seed crystal rod is rotated at a speed of 35rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 55℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Br nonlinear optical crystal with a size of 21mm×14mm×9mm.

[0180] Example 19

[0181] According to the reaction formula: 3CaSO4 + CaCl2 + 3B2O3 → 2Ca2B3O6Cl + 3SO3↑, Ca2B3O6Cl nonlinear optical crystal is prepared.

[0182] CaSO4, CaCl2, B2O3 and LiF-KF-H3BO3 were directly mixed uniformly in a molar ratio of 3:1:3:1, wherein the molar ratio of LiF, KF and H3BO3 in the LiF-KF-H3BO3 system was 2:1:1. The mixture was heated to 750℃ at a heating rate of 18℃ / h, held at that temperature for 65 hours, and then cooled to 720℃ to obtain a mixed melt.

[0183] Preparation of Ca2B3O6Cl seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 6℃ / h, and Ca2B3O6Cl seed crystals were obtained by spontaneous crystallization.

[0184] Crystal growth in mixed 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 for 55 minutes, and then the seed crystal is lowered to the surface of the mixed melt for remelting. The temperature is kept constant for 30 minutes and then reduced to 625℃ at a rate of 45℃ / h.

[0185] The temperature is then slowly reduced at a rate of 3℃ / day, and the seed crystal rod is rotated at a speed of 5 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 15℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Cl nonlinear optical crystal with a size of 20mm×12mm×8mm.

[0186] Example 20

[0187] According to the reaction formula: 3CaSO4 + CaCl2 + 3B2O3 → 2Ca2B3O6Cl + 3SO3↑, Ca2B3O6Br2 nonlinear optical crystals are prepared.

[0188] CaSO4, CaCl2, B2O3 and LiF-KF2 as a co-solvent were directly mixed in a molar ratio of 3:1:3:1, wherein the molar ratio of LiF to KF2 in the LiF-KF2 system was 3:1. The mixture was heated to 760℃ at a heating rate of 30℃ / h, held at that temperature for 20 hours, and then cooled to 700℃ to obtain a mixed melt.

[0189] Preparation of Ca2B3O6Br seed crystals: The obtained mixed melt was slowly cooled to room temperature at a rate of 0.5℃ / h, and Ca2B3O6Br seed crystals were obtained by spontaneous crystallization;

[0190] Crystal growth in mixed melt: The obtained seed crystal is fixed on the seed crystal rod, the seed crystal is lowered from the top of the crystal growth furnace, the seed crystal is preheated for 5 minutes, the seed crystal is lowered into the mixed melt for remelting, the temperature is kept constant for 50 minutes, and the temperature is reduced to 620℃ at a rate of 20℃ / h.

[0191] The temperature is then slowly reduced at a rate of 0.1℃ / day, and the seed crystal rod is rotated at a speed of 5 rpm to grow the crystal. After the single crystal grows to the required size, the crystal is lifted off the surface of the mixed melt and cooled to room temperature at a rate of 10℃ / h. Then the crystal is taken out of the furnace to obtain a Ca2B3O6Br2 nonlinear optical crystal with a size of 13mm×7mm×10mm.

[0192] Example 21

[0193] A frequency doubling device with dimensions of 5mm × 5mm × 6mm is fabricated from any Ca2B3O6X nonlinear optical crystal obtained in Examples 1-20 according to a matching orientation. 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 2 with a wavelength of 1064nm is emitted from the Q-switched Nd:YAG laser 1 and enters the Ca2B3O6X single crystal 3, producing green frequency-doubled light with a wavelength of 532nm. The output intensity is 1.5-2 times that of KDP under the same conditions. The output beam 4 contains infrared light with a wavelength of 1064nm and green light with a wavelength of 532nm. After being filtered by the filter 5, a green laser with a wavelength of 532nm is obtained.

Claims

1. A series of calcium haloborate nonlinear optical crystals characterized by The crystal has a molecular formula of Ca2B3O6X, wherein X = Cl or Br, has no symmetry center, belongs to the orthorhombic system, and has a space group of Pnma Cmc 21 (No. 36), cell parameters: Ca2B3O6Cl: a = 15.406(2) Å, b = 22.115(3) Å, c = 7.3617(11) Å, α = 90, β = 90, γ = 90, Z = 16, V = 2508.2(6) Å 3 ; Ca2B3O6Br: a = 15.360(6) Å, b = 22.175(10) Å, c = 7.454(4) Å, α = 90, β = 90, γ = 90, Z = 16, V = 2538.7(19) Å 3 .

2. The method of claim 1, wherein the series of calcium halogenoborate nonlinear optical crystals are prepared by the method comprising: The crystal is grown by using a cosolvent method, and the specific operation is performed according to the following steps: ​ a. The calcium-containing compounds CaO, CaCO3, Ca(NO3)2, Ca(OH)2 or CaSO4, the halogen-containing compound CaCl2 or CaBr2, and the boron-containing compound H3BO3 or B2O3 are weighed according to the molar ratio of 3:1:6, put into a mortar, mixed and carefully ground, then put into a Φ100mm*100mm open corundum crucible, put into a muffle furnace, slowly heated to 350℃, kept for 24 hours, cooled to room temperature, taken out, secondly ground, then transferred to a Φ350mm*3500mm quartz glass tube, put into a muffle furnace, again heated to 800℃, kept for 48 hours, slowly cooled to room temperature, taken out, ground, to obtain a calcium borate chloride compound or a calcium borate bromide polycrystal powder, and the product is subjected to X-ray analysis, and the obtained X-ray spectrum is consistent with the X-ray spectrum obtained from a series of halogenated calcium borate single crystal structures; b. The calcium borate chloride compound or the calcium borate bromide polycrystal powder obtained in step a is mixed with the cosolvent CaF2, LiF, KF2, LiF-H3BO3, LiF-KF-H3BO3 or LiF-KF2 according to the molar ratio of 1:1-3, heated to a temperature of 700-800℃ at a heating rate of 1-30℃ / h, kept for 15-60 hours, and then decreased to 550-650℃ to obtain a mixed melt; or the calcium-containing compounds CaCO3, Ca(NO3)2 or Ca(OH)2, the halogen-containing compound CaX2 (X = Cl or Br), the boron-containing compound H3BO3 or B2O3, and the cosolvent CaF2, LiF, KF2, LiF-H3BO3, LiF-KF-H3BO3 or LiF-KF2 are mixed according to the molar ratio of 3:1:6:1-3, heated to a temperature of 650-800℃ at a heating rate of 1-30℃ / h, kept for 15-60 hours, and then decreased to 620-700℃ to obtain a mixed melt; c. The mixed melt obtained in step b is slowly decreased to room temperature at a rate of 0.5-10℃ / h, and spontaneously crystallized to obtain a calcium halogenated borate seed crystal; d. The seed crystal obtained in step c is fixed on a seed crystal rod, the seed crystal is lowered from the top of a crystal growth furnace to contact the surface of the mixed melt or to be dissolved in the mixed melt, preheated for 5-60 minutes, kept for 5-60 minutes, and then decreased to a temperature of 620-700℃ at a rate of 1-60℃ / h; e. The temperature is slowly decreased at a rate of 0.1-3℃ / day, the seed crystal rod is rotated at a speed of 1-60 rpm to grow the crystal, the crystal is taken out of the surface of the mixed melt when it grows to a desired size, and then decreased to room temperature at a rate of 10-80℃ / h, and then the crystal is taken out of the furnace, to obtain a calcium halogenated borate nonlinear optical crystal.

3. The method for preparing calcium borate halide nonlinear optical crystal according to claim 2, characterized in that... The molar ratio of LiF to H3BO3 in the co-solvent LiF-H3BO3 system in step b is 1:1-3; the molar ratio of LiF to PbF2 in the LiF-PbF2 system is 2-3:1; and the molar ratio of LiF, NaF and H3BO3 in the LiF-NaF-H3BO3 system is 1-3:1-3:

1.

4. Use of the calcium haloborate nonlinear optical crystal according to claim 1 in the manufacture of a frequency doubler, an up-converter, a down-converter or an optical parametric oscillator.

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