Potassium lanthanum borate, rare earth doped compound and crystal thereof, and preparation method and application thereof

Abstract

The chemical formula of the lanthanum potassium borate compound is K15La7 (BO3) 12, the chemical general formula of the rare earth doped compound of the lanthanum potassium borate is K15 (La1-xREx) 7 (BO3) 12, 0 < x < = 0.3, RE is a rare earth element and is selected from one or more of Nd, Eu, Tb, Ho, Er and Yb, and the rare earth doped compound of the lanthanum potassium borate is selected from one or more of Nd, Eu, Tb, Ho, Er and Yb. The material has the advantages of low cost, easily available resources, simple preparation process, stable physicochemical properties and the like, shows excellent nonlinear optical effect, self-frequency-doubling characteristic and fluorescence property, is expected to become a high-performance nonlinear optical material, and can also be used as an LED fluorescent powder material.

Description

Technical field:

[0001] The invention relates to the technical field of rare earth crystal materials, and in particular to potassium lanthanum borate and rare earth doped compounds and crystals thereof, as well as preparation methods and uses thereof. Background technology:

[0002] Nonlinear optical crystals play a vital role in laser frequency conversion technology. In recent decades, many excellent borate nonlinear optical (NLO) crystals have emerged, such as β-BaB2O4 (BBO), LiB3O5 (LBO), KBe2BO3F2 (KBBF), CsB3O5 (CBO), CsLiB6O 10 (CLBO), etc. These crystals are widely used to produce ultraviolet (UV) or deep ultraviolet (DUV) lasers by frequency conversion of YAG and YVO4 lasers.

[0003] Rare earth borates are an important optical material in the borate system. Since the radii of rare earth elements are similar and their chemical valences are the same, the replacement of rare earth ions usually does not significantly change the crystal structure. Therefore, rare earth borates can have both laser and nonlinear optical properties. YAl3(BO3)4(YAB) is the first rare earth borate nonlinear optical crystal, which outputs ultraviolet laser through Nd:YVO4 laser. Yb doping in YAB 3+ After that, continuous self-doubling green light output can be achieved in Yb:YAB crystal. GdCa4O(BO3)3 (GdCOB), discovered in the 1990s, exhibits excellent nonlinear optical properties and good growth performance. By doping Nd 3+ Ion, Nd 3+ :GdCOB has become the only commercial self-frequency doubling crystal and has achieved significant output power at the green wavelength of 545.5nm. 10 O 19 As a kind of rare earth borate nonlinear optical crystal that has attracted much attention, it exhibits a wide optical transparency range, a large nonlinear coefficient, a high laser damage threshold and excellent anti-deliquescent property. 3+ ions, whose f 0 The electron layer has good optical transmittance, and La 3+ The large distortion of the coordination polyhedron also helps to enhance the nonlinear optical effect. Therefore, it is of great significance to explore new nonlinear optical crystal materials in the lanthanum borate system. Summary of the invention:

[0004] The purpose of the present invention is to provide potassium lanthanum borate and its rare earth doped compound and crystal and its preparation method and use.

[0005] The present invention is achieved through the following technical solutions:

[0006] Potassium lanthanum borate compound, chemical formula K 15 La7(BO3) 12 .

[0007] The preparation method of potassium lanthanum borate compound comprises the following steps:

[0008] A potassium-containing compound, a lanthanum-containing compound and a boron-containing compound are uniformly placed in a mortar according to a molar ratio of potassium: lanthanum: boron of 15:7:12, fully mixed and ground, then placed in a crucible, placed in a muffle furnace, heated to 300-600° C. within 3-6 hours, kept at a constant temperature for 12-48 hours, cooled to room temperature, taken out for a second grinding, then placed in a muffle furnace, heated to 600-750° C., kept at a constant temperature for 12-48 hours, cooled to room temperature, taken out, and after a third grinding, placed in a muffle furnace, heated to 800-850° C., kept at a constant temperature for 12-48 hours, taken out, and ground to obtain a potassium lanthanum borate compound.

[0009] Among them, the potassium-containing compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the boron-containing compound is B2O3 or H3BO3.

[0010] Potassium lanthanum borate crystals, chemical formula K 15 La7(BO3) 12 , belongs to the monoclinic system, point group m, space group Pn, unit cell parameters are α=90°, β=90.342°, γ=90°, Z=4.

[0011] Rare earth doped compounds of potassium lanthanum borate, with the general chemical formula K 15 (La 1-x RE x )7(BO3) 12 , wherein 0<x≤0.3, RE is a rare earth element selected from one or more of Nd, Eu, Tb, Ho, Er, and Yb.

[0012] The present invention also provides a method for preparing a rare earth doped compound of potassium lanthanum borate, comprising the following steps:

[0013] A potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound, and a boron-containing compound are uniformly placed in a mortar according to a molar ratio of potassium: (lanthanum + rare earth): boron element of 15:7:12, mixed and ground thoroughly, then placed in a crucible and placed in a muffle furnace, gradually heated to 300-600°C within 3-6 hours, and kept at a constant temperature within this temperature range for 12-48 hours, then naturally cooled to room temperature, ground again, and after grinding, placed in a muffle furnace again, and heated to 600-750°C within 6 to 7 hours, kept at this temperature range for 12-48 hours, cooled to room temperature and taken out, ground for the third time, placed in a muffle furnace again, heated to 800-850°C, kept at this temperature range for 12-48 hours, taken out and finally ground to obtain a rare earth-doped compound of potassium lanthanum borate.

[0014] The potassium-containing compound is one or more of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3· The rare earth-containing compound is selected from any one of Nd2O3, Nd(NO3)3·6H2O, Eu2O3, Eu(NO3)3·6H2O, Tb2O3, Tb4O7, Tb(NO3)3·6H2O, Ho2O3, Ho(NO3)3·5H2O, Ho(NO3)3·6H2O, Er2O3, Er(NO3)3·6H2O, and Yb2O3; the boron-containing compound is B2O3 or H3BO3.

[0015] Rare earth doped crystals of potassium lanthanum borate, with the general chemical formula K 15 (La 1-x RE x )7(BO3) 12 , where 0<x≤0.3, RE is a rare earth element, selected from one or more of Nd, Eu, Tb, Ho, Er, Yb, belonging to the monoclinic system, m point group, space group is Pn, and the range of unit cell parameters is α=90°, β=90.342-90.017°, γ=90°, Z=4.

[0016] The asymmetric unit in the crystal structure of potassium lanthanum borate and its rare earth doped compounds is composed of three La 1-x RE x (0≤x≤0.3), 8 K, 19 O and 6 B independent lattice sites. 1-x REx (0≤x≤0.3) has a coordination number of 8-9 with O, a coordination number of 7-11 with K, and a coordination number of 3-4 with B. In the crystal structure of potassium lanthanum borate and its rare earth doped compounds, all (La 1-x RE x ) 3+ (0<x≤0.3) are almost in the ac plane, and the layers are connected by strong BO covalent bonds, thus eliminating the layered habit.

[0017] A method for preparing the above-mentioned potassium lanthanum borate crystals, the method comprising the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound, and a boron-containing compound according to a potassium: lanthanum: boron element molar ratio of 6-9:1:4-10, then loading into a crucible, heating to a temperature of 800-1050°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, keeping the temperature for 6-24h, and then cooling to room temperature at a rate of 0.5-5°C / h to obtain potassium lanthanum borate crystals; wherein the potassium-containing compound is K 2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3·; the boron-containing compound is B2O3 or H3BO3.

[0018] In particular, when preparing potassium lanthanum borate crystals, a flux is also added, and the flux is any one of KF, KCl, KBr, K2MoO4 or MoO3.

[0019] When a solvent is added, the preparation method of potassium lanthanum borate crystals is as follows: a potassium-containing compound, a lanthanum-containing compound, a boron-containing compound and a flux are uniformly mixed and ground according to a molar ratio of potassium: lanthanum: boron element: flux of 3-5:1:5-10:2-5, and then loaded into a crucible, heated to a temperature of 800-950°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, kept warm for 6-24h, and then cooled to room temperature at a rate of 0.5-5°C / h to obtain potassium lanthanum borate crystals; wherein the potassium-containing compound The compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the compound containing lanthanum is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the compound containing boron is B2O3 or H3BO3.

[0020] A method for preparing the above-mentioned potassium lanthanum borate rare earth doped crystals, the method comprising the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound, and a boron-containing compound according to a potassium: (lanthanum + rare earth) : boron element molar ratio of 6-9:1:4-10, then loading into a crucible, heating to a temperature of 800-1000°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, keeping the temperature for 6-24h, and then cooling to room temperature at a rate of 0.1-5°C / h to obtain potassium lanthanum borate rare earth doped crystals; wherein the potassium-containing compound is K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, any one of K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the rare earth-containing compound is any one of Nd2O3, Eu2O3, Tb2O3, Tb4O7, Ho2O3, Er2O3, Yb2O3, Nd(NO3)3·6H2O, Eu(NO3)3·6H2O, Tb(NO3)3·6H2O, Ho(NO3)3·5H2O, Ho(NO3)3·6H2O, Er(NO3)3·6H2O; the boron-containing compound is B2O3 or H3BO3.

[0021] When preparing rare earth-doped crystals of potassium lanthanum borate crystals, a flux can also be added, and the flux is any one of KF, KCl, KBr, K2MoO4 or MoO3.

[0022] When a solvent is added, the preparation method of potassium lanthanum borate rare earth doped crystals is as follows: a potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound, and a boron-containing compound are uniformly mixed and ground according to a molar ratio of potassium: (lanthanum + rare earth): boron element: flux of 3-5:1:5-10:2-5, and then loaded into a crucible, heated to a temperature of 800-950°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, kept warm for 6-24h, and then cooled to room temperature at a rate of 0.5-5°C / h to obtain potassium lanthanum borate rare earth doped crystals. body; wherein the potassium-containing compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the boron-containing compound is B2O3 or H3BO3.

[0023] The present invention also protects the use of the potassium lanthanum borate compound or crystal, and the rare earth doped compound or crystal thereof. The potassium lanthanum borate compound and crystal are used as nonlinear optical crystal materials for second harmonic generation, and the potassium lanthanum borate rare earth doped compound or crystal can be used as a self-frequency doubling crystal, or as a phosphor material for LED lighting.

[0024] The beneficial effects of the present invention are as follows: The present invention provides a new type of potassium lanthanum borate and its rare earth doped compounds or crystals and a preparation method thereof, which have the advantages of low cost, easy availability of resources, simple preparation process and stable physical and chemical properties, and exhibit excellent nonlinear optical effects, self-frequency doping characteristics and fluorescence properties, and are expected to become high-performance nonlinear optical materials, and can also be used as LED phosphor materials. Potassium lanthanum borate compounds and crystals can be used as nonlinear optical crystal materials for second harmonic generation, and the potassium lanthanum borate rare earth doped compounds or crystals can be used as self-frequency doubling crystals, or as phosphor materials for LED lighting. It shows important economic and scientific research value in the fields of nonlinear optics and light illumination. Description of the drawings:

[0025] Figure 1 The potassium lanthanum borate K prepared in Example 1 of the present invention 15 La7(BO3) 12 Schematic diagram of the crystal structure of a single crystal along the ac plane;

[0026] Figure 2 The potassium lanthanum borate K prepared in Example 1 of the present invention 15 La7(BO3) 12 Transmission spectrum of a single crystal;

[0027] Figure 3 The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 Solid-state NMR image after single crystal grinding;

[0028] Figure 4 The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 Single crystal infrared spectrum;

[0029] Figure 5 The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 Raman spectrum of single crystal;

[0030] Figure 6 is K prepared in Example 2 15 La7(BO3) 12 Schematic diagram of second harmonic generation of a single crystal;

[0031] Figure 7 is K prepared in Example 4 15 (La 0.99 Nd 0.01 )7(BO3) 12 Schematic diagram of the self-frequency doubling output of a single crystal;

[0032] Figure 8 The potassium lanthanum borate K prepared in Example 1 of the present invention 15 La7(BO3) 12 Powder XRD diffraction pattern of single crystal after grinding;

[0033] Fig. 9 The europium-doped potassium lanthanum borate K prepared in Example 6 of the present invention 15 (La 0.995 Eu 0.005 )7(BO3) 12 Powder XRD diffraction pattern of the compound;

[0034] Fig.10 The Nd-doped potassium lanthanum borate K prepared in Example 7 of the present invention 15 (La 0.99 Nd 0.01 )7(BO3) 12 Powder XRD diffraction pattern of the compound;

[0035] Fig.11 The terbium-doped potassium lanthanum borate K prepared in Example 8 of the present invention 15 (La 0.8 Tb 0.2 )7(BO3) 12 Powder XRD diffraction pattern of the compound;

[0036] Fig.12 The europium-doped potassium lanthanum borate K prepared in Example 6 15 (La 0.995 Eu 0.005 )7(BO3) 12 Fluorescence emission spectra of compounds;

[0037] Fig.13 The europium-doped potassium lanthanum borate K prepared in Example 6 15 (La 0.995 Eu 0.005 )7(BO3) 12 CIE chromaticity coordinates of the compound;

[0038] Fig.14 The europium-doped potassium lanthanum borate K prepared in Example 6 15 (La 0.995 Eu 0.005 )7(BO3)12 Fluorescence lifetime diagram of the compounds. Specific implementation method:

[0039] The following is a further description of the present invention, rather than a limitation of the present invention.

[0040] Example 1: Self-solvent method potassium lanthanum borate K 15 La7(BO3) 12 Crystal

[0041] Raw materials used (analytical grade): KHCO3 0.09 mol, La2O3 0.005 mol, H3BO3 0.05 mol.

[0042] The specific steps are as follows: weigh the above raw materials, mix and grind them in a mortar, and then put them into The gold crucible was placed in a molten salt furnace and heated to 850°C at 100°C / h. The temperature was kept for 18 hours until the raw material was completely melted. Then the temperature was slowly lowered at a rate of 1.5°C / h to obtain a 0.63×0.32×0.28mm 3 K 15 La7(BO3) 12 Crystal.

[0043] Example 2: Solvent-assisted potassium lanthanum borate K 15 La7(BO3) 12 Crystal

[0044] Raw materials used (analytical grade): K2CO3 0.25 mol, La2O3 0.05 mol, B2O3 0.5 mol, KF 0.5 mol.

[0045] The specific steps are as follows: weigh the above raw materials, mix and grind them in a mortar, and then put them into The crucible was placed in a platinum crucible, and then placed in a molten salt furnace, heated to 920°C at 50°C / h, and kept warm for 12 hours until the raw materials were completely melted. Then the seed crystal tied with platinum wire was slowly put into the crucible, and then the temperature was slowly lowered at a rate of 1°C / hour. Before the melt solidified, the crystal was taken out of the liquid surface to obtain a crystal with a size of 2.53×2.63×1.58cm 3 K 15 La7(BO3) 12 Crystal.

[0046] Example 3: Europium-doped crystals of potassium lanthanum borate K 15 (La 0.8 Eu 0.2 )7(BO3) 12 Crystal

[0047] Raw materials used (analytical grade): KOH 0.08 mol, La(NO3)3·6H2O 0.008 mol, Eu(NO3)3·6H2O 0.002 mol, H3BO3 0.08 mol.

[0048] The specific steps are as follows: weigh the above raw materials, mix and grind them in a mortar, and then put them into The gold crucible was placed in a molten salt furnace and heated to 920°C at 50°C / h. The temperature was kept for 24 hours until the raw material was completely melted. Then the temperature was slowly lowered at a rate of 2.0°C / h to obtain a 0.54×0.42×0.13mm 3 K 15 (La 0.8 Eu 0.2 )7(BO3) 12 Crystal.

[0049] Example 4: Preparation of Nd-doped Potassium Lanthanum Borate K by Solvent Co-solvent Method 15 (La 0.99 Nd 0.01 )7(BO3) 12 Crystal

[0050] Raw materials used (analytical grade): KHCO3 0.4 mol, La2O3 0.0495 mol, Nd2O3 0.0005 mol, H3BO3 1.0 mol, KF 0.3 mol.

[0051] The specific steps are as follows: weigh the above raw materials, mix and grind them in a mortar, and then put them into The crucible was placed in a platinum crucible, and then placed in a molten salt furnace, heated to 935°C at 50°C / h, and kept warm for 12 hours until the raw materials were completely melted. Then the seed crystal tied with platinum wire was slowly put into the crucible, and then the temperature was slowly lowered at a rate of 0.5°C / h. Before the melt solidified, the crystal was taken out of the liquid surface to obtain a crystal with a size of 2.86×2.73×2.08cm 3 K 15 (La 0.99 Nd 0.01 )7(BO3) 12 Crystal.

[0052] Example 5: Synthesis of Potassium Lanthanum Borate K 15 La7(BO3) 12 Compound

[0053] Raw materials used (analytical grade): KHCO3 0.15 mol, La(OH)3 0.07 mol, H3BO3 0.12 mol.

[0054] The specific steps are as follows: weigh the above raw materials, mix and grind them carefully in an agate mortar, and then put them into The platinum crucible is placed in a muffle furnace, heated to 600°C for 6 hours, kept at this temperature for 12 hours, cooled to room temperature, taken out, and put into a muffle furnace after a second grinding, and then heated to 700°C, kept at this temperature for 24 hours, cooled to room temperature, taken out, and put into a muffle furnace after a third grinding, and then heated to 825°C, kept at this temperature for 48 hours, taken out, and ground to obtain the potassium lanthanum borate K of the present invention. 15 La7(BO3) 12 Compound.

[0055] Example 6: Synthesis of Europium-doped Potassium Lanthanum Borate K 15 (La 0.995 Eu 0.005 )7(BO3) 12 Compound

[0056] Raw materials used (analytical grade): KNO3 0.15 mol, La(NO3)3·6H2O 0.06965 mol, Eu(NO3)3·6H2O 0.00035 mol, H3BO3 0.12 mol.

[0057] The specific steps are as follows: weigh the above raw materials, mix and grind them carefully in an agate mortar, and then put them into The gold crucible was heated to 300°C, kept at the constant temperature for 48 hours, cooled to room temperature, taken out, and put into a muffle furnace after a second grinding. The temperature was then raised to 600°C, kept at the constant temperature for 24 hours, cooled to room temperature, taken out, and put into a muffle furnace after a third grinding. The temperature was then raised to 820°C, kept at the constant temperature for 24 hours, taken out, and the K of the present invention was obtained by grinding. 15 (La 0.995 Eu 0.005 )7(BO3) 12 Compound.

[0058] Example 7: Synthesis of Nd-doped Potassium Lanthanum Borate K 15 (La 0.99 Nd 0.01 )7(BO3) 12 Compound

[0059] Raw materials used (analytical grade): K2C2O4 0.075 mol, La(NO3)3·6H2O 0.0693 mol, Nd(NO3)3·6H2O 0.0007 mol, H3BO3 0.12 mol.

[0060] The specific steps are as follows: weigh the above raw materials, mix and grind them carefully in an agate mortar, and then put them into The gold crucible was heated to 500°C, kept at this temperature for 24 hours, cooled to room temperature, taken out, and put into a muffle furnace after a second grinding. The temperature was then raised to 650°C, kept at this temperature for 24 hours, cooled to room temperature, taken out, and put into a muffle furnace after a third grinding. The temperature was then raised to 825°C, kept at this temperature for 24 hours, taken out, and the K of the present invention was obtained by grinding. 15 (La 0.99 Nd 0.01 )7(BO3) 12 Compound.

[0061] Example 8: Synthesis of Terbium-doped Potassium Lanthanum Borate K 15 (La 0.8 Tb 0.2 )7(BO3) 12 Compound

[0062] Raw materials used (analytical grade): KHCO3 0.03 mol, KBO2 0.12 mol, La2O3 0.028 mol, Tb4O7 0.0035 mol.

[0063] The specific steps are as follows: weigh the above raw materials, mix and grind them carefully in an agate mortar, and then put them into The gold crucible was heated to 450°C, kept at this temperature for 12 hours, cooled to room temperature, taken out, and put into a muffle furnace after a second grinding. The temperature was then raised to 650°C, kept at this temperature for 24 hours, cooled to room temperature, taken out, and put into a muffle furnace after a third grinding. The temperature was then raised to 850°C, kept at this temperature for 48 hours, taken out, and the K of the present invention was obtained by grinding. 15 (La 0.8 Tb 0.2 )7(BO3) 12 Compound.

[0064] Example 9: Characteristic Testing of Potassium Lanthanum Borate and Its Rare Earth Doped Compounds and Crystals

[0065] The potassium lanthanum borate K prepared in Example 1 of the present invention 15 La7(BO3) 12 The unit cell structure of the single crystal was determined by X-ray single crystal diffraction method. Figure 1 As shown by Figure 1 It can be concluded that the potassium lanthanum borate crystal K 15 La7(BO3) 12 It belongs to the monoclinic system, the polar m point group, the space group is Pn, and the unit cell parameters are: α=90°, β=90.342°, γ=90°, Z=4.

[0066] The 1% neodymium doped K 15 (La 0.99 Nd 0.01 )7(BO3) 12 The single crystal was measured by X-ray single crystal diffraction method to determine the unit cell structure, and K 15 (La 0.99 Nd 0.01 )7(BO3) 12 The crystal belongs to the monoclinic system, polar m point group, space group is Pn, and the unit cell parameters are: α=90°, β=90.336°, γ=90°, Z=4.

[0067] The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 The single crystal was tested by solid-state nuclear magnetic resonance, Fourier transform infrared, and Raman spectroscopy. The results are as follows Figure 3-5 As shown, it is proved that the B atom is 3- or 4-coordinated with O, which further verifies the crystal structure analyzed by X-ray diffraction.

[0068] The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 The single crystal was tested through the transmission spectrum, and the results were as follows Figure 3 As shown, it has good transmittance in the test range, proving that it can be used as an optical material in the infrared-visible light band.

[0069] The potassium lanthanum borate K prepared in Example 2 of the present invention 15 La7(BO3) 12 After single crystal is cut and polished in matching direction, the processing size is 1cm×0.8cm×0.6cm wafer, and the optical path is as follows Figure 6 As shown, a Nd:YAG laser with an incident wavelength of 1064nm is used as a light source, and the filter filters the fundamental frequency light to produce green doubled frequency light with an output wavelength of 532nm, proving its use as a nonlinear optical material.

[0070] The 1% Nd doped K prepared in Example 4 of the present invention 15 (La 0.99 Nd 0.01 )7(BO3) 12 The crystal is cut and polished in the matching direction to produce a 1.2cm×0.8cm×0.8cm wafer. A laser diode is used as the pump source. The wafer is placed in the optical resonant cavity through an optical focusing system. The optical path is as follows: Figure 7 As shown, green light with a self-doubled wavelength of 540 nm can be generated, proving its use as a self-doubled frequency material.

[0071] The K prepared in Examples 1, 6, 7 and 8 of the present invention 15 La7(BO3) 12 Single crystal, K 15 (La 0.995 Eu 0.005 )7(BO3) 12 , K 15 (La 0.99 Nd 0.01 )7(BO3) 12 , K 15 (La 0.8 Tb 0.2 )7(BO3) 12 After the compound is carefully ground, an X-ray powder diffractometer is used to perform a room temperature XRD test, such as Figure 8-11 As shown, the results show that the prepared compound is a pure phase without other obvious impurities.

[0072] The K prepared in Example 6 of the present invention 15 (La 0.995 Eu 0.005 )7(BO3) 12 The compound, after careful grinding, emits characteristic red light under ultraviolet or visible light excitation. Its fluorescence emission spectrum is as follows Fig.12 As shown, its CIE chromaticity coordinates (0.656, 0.343, 0.000) are Fig.13 The fluorescence lifetime and its decay curve are shown in Fig.14 As shown, red phosphor has good use value in LED.

Claims

1. Chemical formula is K 15 La7(BO3) 12 The potassium lanthanum borate compound is characterized in that The preparation method comprises the following steps: uniformly placing a potassium-containing compound, a lanthanum-containing compound and a boron-containing compound in a mortar according to a molar ratio of potassium: lanthanum: boron of 15:7:12, fully mixing and grinding, then placing the compounds in a crucible, placing the compounds in a muffle furnace, heating the compounds to 300-600°C within 3-6 hours, keeping the temperature constant for 12-48 hours, cooling the compounds to room temperature, taking the compounds out for a second grinding, then placing the compounds in a muffle furnace, heating the compounds to 600-750°C, keeping the temperature constant for 12-48 hours, cooling the compounds to room temperature, taking the compounds out, grinding the compounds for a third time, then heating the compounds to 800-850°C, keeping the temperature constant for 1 2-48 hours, take out and grind to obtain potassium lanthanum borate compound; the potassium-containing compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the boron-containing compound is B2O3 or H3BO3.

2. Potassium lanthanum borate crystal, characterized in that: The chemical formula is K 15 La7(BO3) 12 , belongs to the monoclinic system, point group m, space group Pn, unit cell parameters are α=90°, β=90.342°, γ=90°, Z=4.

3. A rare earth doped compound of potassium lanthanum borate, characterized in that: The chemical formula is K 15 (La 1-x RE x )7(BO3) 12 , wherein 0<x≤0.3, RE is a rare earth element selected from one or more of Nd, Eu, Tb, Ho, Er, and Yb.

4. Rare earth doped crystal of potassium lanthanum borate, characterized in that: The chemical formula is K 15 (La 1-x RE x )7(BO3) 12 , where 0<x≤0.3, RE is a rare earth element, selected from one or more of Nd, Eu, Tb, Ho, Er, Yb, belonging to the monoclinic system, m point group, space group is Pn, and the range of unit cell parameters is α=90°, β=90.342-90.017°, γ=90°, Z=4.

5. A method for preparing potassium lanthanum borate crystals according to claim 2, characterized in that: The method comprises the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound and a boron-containing compound according to a potassium: lanthanum: boron element molar ratio of 6-9:1:4-10, then loading the mixture into a crucible, heating the mixture to a temperature of 800-1050°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, preserving the temperature for 6-24h, and then cooling the mixture to room temperature at a rate of 0.5-5°C / h to obtain potassium lanthanum borate crystals; wherein the potassium-containing compound is K2CO3, KHC O3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3·; the boron-containing compound is B2O3 or H3BO3.

6. The method for preparing potassium lanthanum borate crystals according to claim 5, characterized in that: A solvent is also added, and the flux is any one of KF, KCl, KBr, K2MoO4 or MoO3, comprising the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound, a boron-containing compound and a flux according to a molar ratio of potassium: lanthanum: boron element: flux of 3-5:1:5-10:2-5, and then loading into a crucible, heating to a temperature of 800-950°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, keeping the temperature for 6-24h, and then cooling to room temperature at a rate of 0.5-5°C / h to obtain boric acid Potassium lanthanum crystals; wherein the potassium-containing compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the boron-containing compound is B2O3 or H3BO3.

7. A method for preparing the rare earth doped potassium lanthanum borate compound according to claim 3, characterized in that: The invention comprises the following steps: putting a potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound and a boron-containing compound into a mortar in a molar ratio of potassium: (lanthanum + rare earth): boron element of 15:7:12, mixing and grinding them, then putting them into a crucible and placing them into a muffle furnace, gradually heating them to 300-600°C within 3-6 hours, and keeping a constant temperature within the temperature range for 12-48 hours, then cooling them naturally to room temperature, grinding them again, putting them into the muffle furnace again after grinding, heating them to 600-750°C within 6 to 7 hours, keeping them within the temperature range for 12-48 hours, cooling them to room temperature and taking them out, grinding them for the third time, putting them into the muffle furnace again, heating them to 800-850°C, keeping them within the temperature range for 12-48 hours, taking them out and grinding them finally, so as to obtain a rare earth doped compound of potassium lanthanum borate; wherein the potassium-containing compound is K2CO3, KH One or more of CO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3·; a rare earth-containing compound Selected from any one of Nd2O3, Nd(NO3)3·6H2O, Eu2O3, Eu(NO3)3·6H2O, Tb2O3, Tb4O7, Tb(NO3)3·6H2O, Ho2O3, Ho(NO3)3·5H2O, Ho(NO3)3·6H2O, Er2O3, Er(NO3)3·6H2O, Yb2O3; the boron-containing compound is B2O3 or H3BO3.

8. A method for preparing the potassium lanthanum borate rare earth doped crystal according to claim 4, characterized in that: The method comprises the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound and a boron-containing compound according to a potassium: (lanthanum + rare earth) : boron element molar ratio of 6-9:1:4-10, then loading the mixture into a crucible, heating the mixture to a temperature of 800-1000°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, keeping the temperature for 6-24h, and then cooling the mixture to room temperature at a rate of 0.1-5°C / h to obtain a potassium borate lanthanum rare earth doped crystal; wherein the potassium-containing compound is K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2 O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3·; the rare earth-containing compound is any one of Nd2O3, Eu2O3, Tb2O3, Tb4O7, Ho2O3, Er2O3, Yb2O3, Nd(NO3)3·6H2O, Eu(NO3)3·6H2O, Tb(NO3)3·6H2O, Ho(NO3)3·5H2O, Ho(NO3)3·6H2O, Er(NO3)3·6H2O; the boron-containing compound is B2O3 or H3BO3.

9. The method for preparing potassium lanthanum borate rare earth doped crystals according to claim 8, characterized in that: A solvent is also added, and the flux is any one of KF, KCl, KBr, K2MoO4 or MoO3, comprising the following steps: uniformly mixing and grinding a potassium-containing compound, a lanthanum-containing compound, a rare earth-containing compound, and a boron-containing compound according to a molar ratio of potassium: (lanthanum + rare earth): boron element: flux of 3-5:1:5-10:2-5, and then loading into a crucible, heating to a temperature of 800-950°C at a heating rate of 50-100°C / h to obtain a high-temperature melt, keeping the temperature for 6-24h, and then cooling to room temperature at a rate of 0.5-5°C / h, Potassium borate lanthanum rare earth doped crystals are obtained; the potassium-containing compound is any one of K2CO3, KHCO3, CH3COOK, K2C2O4, KNO3, KOH or KBO2, K2B2O4·3H2O, K2B4O7, K2B4O7·4H2O; the lanthanum-containing compound is any one of La2O3, La(NO3)3·6H2O, La2(C2O4)3, La(CH3COO)3, La(OH)3, La2(CO3)3; the boron-containing compound is B2O3 or H3BO3.

10. Use of the potassium lanthanum borate compound according to claim 1 or the potassium lanthanum borate crystal according to claim 2, and the rare earth-doped compound of potassium lanthanum borate according to claim 3 or the rare earth-doped crystal of potassium lanthanum borate according to claim 4, characterized in that: The potassium lanthanum borate compound and crystal are used as nonlinear optical crystal materials for second harmonic generation, and the potassium lanthanum borate rare earth doped compound or crystal can be used as a self-frequency doubling crystal or as a phosphor material for LED lighting.

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