Red fluorescent powder of europium ion doped lanthanum fluoride nanoparticles

Abstract

According to the europium ion-doped lanthanum fluoride nanoparticle red phosphor, europium ion doping is carried out by taking the lanthanum fluoride nanoparticles as a base material, both lanthanum and europium are lanthanide elements, atomic extranuclear electrons are approximately arranged, the radiuses of the ions are the same, and the europium ions are more easily doped in lanthanum salt. Europium ions in the beta-diketo complex can only replace lanthanum ions located on the surfaces of the lanthanum fluoride nanoparticles, are bonded with fluorine ions to form bonds and cannot enter crystal lattices of the lanthanum fluoride nanoparticles, finally, the surfaces of the lanthanum fluoride nanoparticles are evenly coated with the beta-diketo complex, and the particle size of the particles is controlled to be 3-7 nanometers. Through experimental determination, under the same determination condition, the energy of the prepared sample is concentrated on excitation of red fluorescence, and the luminous intensity of the red light is improved by more than one hundred times. The red fluorescent powder is prepared by adopting the method, the preparation method is simple, the cost is reduced, the performance of the complex is optimized, the luminous efficiency and the luminous intensity of the red fluorescent powder are relatively high, and the application range of the red fluorescent powder can be expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of red fluorescent powder, and in particular relates to red fluorescent powder doped with europium ions and lanthanum fluoride nanoparticles. Background Art

[0002] Rare earth ion doped nanoparticles have unique luminescent properties and have considerable application potential in the fields of display, lighting, laser, information security, and sensing. Since lanthanum fluoride has low phonon energy and very small multi-phonon relaxation in the excited state, it is an ideal matrix material for various fluorescent powders. Europium ions are rare earth ions that emit red and orange fluorescence. The color of the fluorescence emitted depends on the position of the europium ions in the matrix. When the europium ions are located in a highly symmetrical position in the matrix, the probability of emitting orange fluorescence is high, and when they are located in an asymmetric position in the matrix, the probability of emitting red fluorescence is high. The smaller the particle size of the luminescent powder, the larger its specific surface area, which can fully absorb the excitation energy and increase the probability of the europium ions being on the surface of the particles, that is, the probability of the europium ions being located in an asymmetric position in the matrix increases. Therefore, the smaller the particle size of the luminescent powder, the higher the intensity of the emitted fluorescence, and the greater the probability of the europium ions emitting red fluorescence.

[0003] In recent years, luminescent materials of rare earth ion-doped inorganic nanoparticles have received extensive attention. Compared with traditional nanoluminescent materials (such as fluorescent dyes and quantum dots), luminescent materials of rare earth ion-doped inorganic nanoparticles have advantages such as good photochemical stability, long fluorescence lifetime, and tunable fluorescence emission wavelength. However, due to the surface fluorescence quenching effect, its further application is limited. So far, how to significantly improve the luminescent performance of luminescent materials of rare earth ion-doped inorganic nanoparticles is still a major problem faced by everyone.

[0004] Through searching, we know that there are many existing patents related to red fluorescent materials. For example, 1. "A red rare earth fluorescent material and its preparation method" (patent number: 201510837621X), with rare earth europium as the luminescent center ion, o-methoxybenzoic acid with high rigidity and good conjugation performance as the first ligand, and polyamide-amine dendrimer with good energy transfer effect and three-dimensional structure as the second ligand. The luminescence intensity of the prepared material is 2.5 times that of the binary complex without PAMAM under the same test conditions, and 1.3 times that of the ternary complex with o-phenanthroline as the second ligand under the same test conditions. 2. "A red luminescent uniform porous rare earth composite material, preparation method and application" (patent number: 2017105202713), the rare earth europium complex of this material is covalently bonded to the cellulose macromolecular network, and emits pure red fluorescence under ultraviolet light, which has potential application prospects in the field of luminescent display and new porous materials. 3. "A red luminescent rare earth composite material, preparation method and application" (Patent No.: 2017104871880). The composite material is CHDP / Eu, where CHDP is a chitosan biomacromolecule modified with 2,3-pyridinedicarboxylic anhydride, and Eu is a rare earth europium ion. The composite material is in the form of a hydrogel and can emit the characteristic red fluorescence of rare earth europium ions. The prepared composite material is non-toxic to rat thoracic aortic endothelial cells (RAECs), has good biocompatibility, and can be used as a bioluminescent imaging material. 4. "A strong red fluorescent rare earth nanoparticle and its preparation method and application in cell fluorescence imaging" (Patent No.: 2018104926816). It utilizes the dual energy transfer effect of carbon quantum dots and terbium ions, and can emit strong light in aqueous solution without the use of organic ligands. It overcomes the shortcomings of conventional fluorescent imaging materials containing organic ligands, which require complex organic synthesis and poor water solubility and require organic solvents for solubilization. It has low cytotoxicity, good biocompatibility and safety, and can be used in cell fluorescence imaging. 5. "A rare earth-doped scandium oxide nanomaterial, its preparation method and application" (Patent No.: 2019101274529). The nanomaterial includes a europium ion-doped scandium oxide nanoparticle core, an oil-soluble ligand on the oxide surface and a surface modification layer with a cavity structure formed by an external amphiphilic ligand, and a rare earth ion sensitizer loaded in the cavity. The surface modification layer is adsorbed on the surface of the oil-soluble ligand. The red luminescence intensity of the rare earth-doped ultra-small scandium oxide nanomaterial after surface modification and loading of the rare earth ion sensitizer is 3 orders of magnitude higher than that of the unmodified rare earth-doped ultra-small scandium oxide nanomaterial, and has great development potential in the fields of biological imaging and biological detection.

[0005] It can be seen that europium ion complexes require the design and optimization of ligands, and changes in ligands have a great impact on the luminescent properties of the complexes. The luminous efficiency, luminous intensity and stability of the red light of the complexes can be improved by changing the ligands. However, the existing red fluorescent materials have the disadvantages of complex preparation methods, high production costs and narrow application ranges. Under this background, the inventors of this application have worked hard to develop a red fluorescent powder of europium ion-doped lanthanum fluoride nanoparticles, which has high luminous efficiency and luminous intensity, and a simple preparation method, which not only reduces costs but also optimizes the performance of the complex, thereby expanding the application range of the red fluorescent powder. Summary of the invention

[0006] The present invention mainly solves the technical problems existing in the prior art and provides a red fluorescent powder of europium ion-doped lanthanum fluoride nanoparticles.

[0007] The above technical problems of the present invention are mainly solved by the following technical scheme: a red fluorescent powder doped with europium ions and lanthanum fluoride nanoparticles, wherein the preparation method of the red fluorescent powder comprises the following steps: step (1), preparing solution A, adding oleic acid to ethanol, wherein the volume ratio of oleic acid to ethanol is 1:20-60, stirring at 60-80°C for 20-40 minutes, then dripping a deionized water solution containing a fluorine source, stirring while dripping, so that the pH value is within the range of 4-6, and continuing to maintain 60-80°C during the dripping process; step (2), preparing solution B, adding an organic substance containing a β-diketonate organic ligand to ethanol, wherein the volume ratio of the organic substance containing a β-diketonate organic ligand to ethanol is 1:10-30, and stirring at 60 -80 ℃ stirring for 20-40 minutes, then add europium source and lanthanum source, stir at 60-80 ℃ for 1-3 hours; step (3), add solution B dropwise into solution A, stirring while adding dropwise, and keep the temperature at 60-80 ℃; step (4), pour the mixed solution of step (3) into a reactor, the temperature of the reactor is 110-140 ℃, and keep it for 10-14 hours; step (5), after the reactor is naturally cooled, take out the reactant of step (4), centrifuge it with a centrifuge, remove the supernatant, and then wash the precipitate with deionized water, and repeat the process 3-5 times; step (6), place the product of step (5) in a vacuum environment at 40-60 ℃, dry it for 10-14 hours, and obtain a red phosphor of europium ion doped lanthanum fluoride nanoparticles. Wherein, the fluorine source in step (1) is sodium fluoride or ammonium fluoride or a mixture of the two, and the analytical purity is ≥99.7%; the organic matter containing the β-diketonate organic ligand in step (2) is acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof; the europium source in step (2) is europium nitrate or europium oxide or a mixture of the two, and the analytical purity is ≥99.7%, and the concentration of europium ions in ethanol is 0.0008-0.0025 mmol / ml; the lanthanum source in step (2) is lanthanum oxide or lanthanum nitrate or a mixture of the two, and the analytical purity is ≥99.7%, and the concentration of lanthanum ions in ethanol is 0.015-0.055 mmol / ml.

[0008] The present invention uses lanthanum fluoride nanoparticles as a matrix material for europium ion doping. Lanthanum and europium are both lanthanide elements, and their electron configurations outside the nucleus are similar. The ion radius is the same, and europium ions are more easily doped in lanthanum salts. In the technical scheme of the present invention, solution A is first prepared with an ethanol solution of oleic acid, and the oleic acid is evenly distributed in ethanol. Then, after adding a deionized aqueous solution of sodium fluoride or ammonium fluoride or a mixture of the two, it is beneficial to the isolation of oleic acid molecules, so that the fluoride ions are evenly dispersed in solution A; solution B is first prepared with an ethanol solution of acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof, and acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof are evenly distributed in ethanol. Then, after adding europium nitrate or europium oxide or a mixture of the two, since acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate all contain β-diketonate organic ligands, Europium ions and beta-diketone acid form a beta-diketone complex; lanthanum oxide or lanthanum nitrate or a mixture of the two is also added to solution B. In the process of adding solution B to solution A, lanthanum ions are bonded with uniformly dispersed fluorine ions to form lanthanum fluoride crystal nuclei. Subsequently, during high-temperature reaction in a reactor, the presence of oleic acid can prevent the generated lanthanum fluoride crystal nuclei from growing into large particles due to large aggregation, thereby controlling the size of lanthanum fluoride nanoparticles to be no larger than 3-5 nanometers, and the size of lanthanum fluoride nanoparticles is uniform and evenly distributed. At the same time, due to the large volume of the beta-diketone complex, the europium ions in the beta-diketone complex can only replace the lanthanum ions located on the surface of the lanthanum fluoride nanoparticles and bond with the fluorine ions, and cannot enter the lattice of the lanthanum fluoride nanoparticles. Finally, the β-diketone complex is evenly coated on the surface of lanthanum fluoride nanoparticles, and the particle size is controlled between 3-7 nanometers. First, the europium ions are placed on the surface of the lanthanum fluoride nanoparticles, increasing the probability of emitting red fluorescence. Second, the β-diketone complex can absorb excitation energy and effectively transfer the energy to the europium ions. Third, the quenching effect within the lanthanum fluoride nanoparticles is suppressed, thereby improving the red fluorescence emission intensity and luminescence efficiency.

[0009] The present invention is used to prepare red fluorescent powder, the preparation method is simple, the cost is reduced and the performance of the complex is optimized, the luminous efficiency and luminous intensity of the red fluorescent powder are both high, and its application range can be expanded. After experimental measurement, under the same measurement conditions, the sample prepared by the present invention is excited with an excitation light wave of 375 nanometers, the orange light relative intensity of the sample prepared by the present invention is 5693, and the red light intensity is 14327, and the orange light relative intensity of the sample without using organic ligands and oleic acid is 429, and the red light intensity is 142. Calculation shows that the relative intensity ratio of the red fluorescence to the orange fluorescence of the sample prepared by the present invention is 2.517, and the relative intensity ratio of the red fluorescence to the orange fluorescence of the sample without using organic ligands and oleic acid is 0.331, and the two relative intensity ratios are increased by 7.6 times. The energy of the sample prepared by the present invention is concentrated on the excitation of red fluorescence, and the red light luminous intensity is increased by more than 100 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a comparison diagram of the fluorescence emission intensities of different complexes, wherein line a is the fluorescence emission intensity of the sample prepared by the present invention, and line b is the fluorescence emission intensity of the sample without using organic ligands and oleic acid. DETAILED DESCRIPTION

[0011] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0012] Example:

[0013] A red fluorescent powder doped with europium ions and lanthanum fluoride nanoparticles. The preparation method of the red fluorescent powder comprises the following steps: step (1), preparing solution A, adding oleic acid to ethanol, wherein the volume ratio of oleic acid to ethanol is 1:20-60, stirring at 60-80°C for 20-40 minutes, then dripping a deionized water solution containing a fluorine source, stirring while dripping, so that the pH value is within the range of 4-6, and maintaining 60-80°C during the dripping process; step (2), preparing solution B, adding an organic substance containing a β-diketonate organic ligand to ethanol, wherein the volume ratio of the organic substance containing the β-diketonate organic ligand to ethanol is 1:10-30, stirring at 60-80°C for 20-40 minutes. minutes, then add the europium source and the lanthanum source, and stir at 60-80°C for 1-3 hours; step (3), add solution B dropwise to solution A, stirring while adding dropwise, and maintaining the temperature of 60-80°C; step (4), pour the mixed solution of step (3) into a reactor, the temperature of the reactor is 110-140°C, and maintain for 10-14 hours; step (5), after the reactor is naturally cooled, take out the reactant of step (4), centrifuge it with a centrifuge, remove the supernatant, and then wash the precipitate with deionized water, and repeat the process 3-5 times; step (6), place the product of step (5) in a vacuum environment at 40-60°C, and dry it for 10-14 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles. Wherein, the fluorine source in step (1) is sodium fluoride or ammonium fluoride or a mixture of the two, and the analytical purity is ≥99.7%; the organic matter containing the β-diketonate organic ligand in step (2) is acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof; the europium source in step (2) is europium nitrate or europium oxide or a mixture of the two, and the analytical purity is ≥99.7%, and the concentration of europium ions in ethanol is 0.0008-0.0025 mmol / ml; the lanthanum source in step (2) is lanthanum oxide or lanthanum nitrate or a mixture of the two, and the analytical purity is ≥99.7%, and the concentration of lanthanum ions in ethanol is 0.015-0.055 mmol / ml.

[0014] The present invention uses lanthanum fluoride nanoparticles as a matrix material for europium ion doping. Lanthanum and europium are both lanthanide elements, and their electron configurations outside the nucleus are similar. The ion radius is the same, and europium ions are more easily doped in lanthanum salts. In the technical scheme of the present invention, solution A is first prepared with an ethanol solution of oleic acid, and the oleic acid is evenly distributed in ethanol. Then, after adding a deionized aqueous solution of sodium fluoride or ammonium fluoride or a mixture of the two, it is beneficial to the isolation of oleic acid molecules, so that the fluoride ions are evenly dispersed in solution A; solution B is first prepared with an ethanol solution of acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof, and acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof are evenly distributed in ethanol. Then, after adding europium nitrate or europium oxide or a mixture of the two, since acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate all contain β-diketonate organic ligands, Europium ions and beta-diketone acid form a beta-diketone complex; lanthanum oxide or lanthanum nitrate or a mixture of the two is also added to solution B. In the process of adding solution B to solution A, lanthanum ions are bonded with uniformly dispersed fluorine ions to form lanthanum fluoride crystal nuclei. Subsequently, during high-temperature reaction in a reactor, the presence of oleic acid can prevent the generated lanthanum fluoride crystal nuclei from growing into large particles due to large aggregation, thereby controlling the size of lanthanum fluoride nanoparticles to be no larger than 3-5 nanometers, and the size of lanthanum fluoride nanoparticles is uniform and evenly distributed. At the same time, due to the large volume of the beta-diketone complex, the europium ions in the beta-diketone complex can only replace the lanthanum ions located on the surface of the lanthanum fluoride nanoparticles and bond with the fluorine ions, and cannot enter the lattice of the lanthanum fluoride nanoparticles. Finally, the β-diketone complex is evenly coated on the surface of lanthanum fluoride nanoparticles, and the particle size is controlled between 3-7 nanometers. First, the europium ions are placed on the surface of the lanthanum fluoride nanoparticles, increasing the probability of emitting red fluorescence. Second, the β-diketone complex can absorb excitation energy and effectively transfer the energy to the europium ions. Third, the quenching effect within the lanthanum fluoride nanoparticles is suppressed, thereby improving the red fluorescence emission intensity and luminescence efficiency.

[0015] The red fluorescent powder is prepared by the present invention, the preparation method is simple, the cost is reduced and the performance of the complex is optimized, the luminous efficiency and luminous intensity of the red fluorescent powder are both high, and the application range thereof can be expanded.

[0016] Preparation of sample example 1: Prepare solution A by adding 1.0 ml of oleic acid to 40 ml of ethanol, stirring at 70°C for 30 minutes, then dropwise adding a deionized aqueous solution of sodium fluoride, the analytical purity of which is 99.8%, and stirring while dropping until the pH value is 5, and continue to maintain 70°C during the dropping process; Step (2), prepare solution B by adding 2.0 ml of acetylacetone to 40 ml of ethanol, stirring at 70°C for 30 minutes, then adding 0.06 mmol of europium nitrate and 1.1 mmol of lanthanum nitrate, the analytical purity of which is 99.8%. .8%, and stirring at 70°C for 3 hours; step (3), adding solution B dropwise into solution A, stirring while adding dropwise, and maintaining the temperature at 70°C; step (4), pouring the mixed solution of step (3) into a reactor, the temperature of the reactor is 125°C, and maintaining it for 13 hours; step (5), after the reactor is naturally cooled, taking out the reactant of step (4), centrifuging and washing with deionized water, and removing the supernatant, and treating it 5 times; step (6), placing the product of step (5) in a vacuum environment of 50°C, and drying it for 14 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0017] Preparation of sample example 2: Prepare solution A by adding 1.5 ml of oleic acid to 45 ml of ethanol, stirring at 60° C. for 40 minutes, then dropwise adding deionized ammonium fluoride aqueous solution, the analytical purity of ammonium fluoride is 99.8%, stirring while dropping until the pH value is 6, and maintaining 60° C. during the dropping process; Step (2), prepare solution B by adding 2.5 ml of methyl acetoacetate to 45 ml of ethanol, stirring at 80° C. for 40 minutes, then adding 0.07 mmol of europium nitrate and 1.5 mmol of lanthanum nitrate, the analytical purity of europium nitrate and lanthanum nitrate is 9 9.8%, stirring at 80°C for 3 hours; step (3), adding solution B dropwise to solution A, stirring while adding dropwise, and maintaining the temperature at 80°C; step (4), pouring the mixed solution of step (3) into a reactor, the temperature of the reactor is 140°C, and maintaining it for 12 hours; step (5), after the reactor is naturally cooled, taking out the reactant of step (4), centrifuging and washing with deionized water, and removing the supernatant, and treating it 5 times; step (6), placing the product of step (5) in a vacuum environment at 60°C, and drying it for 12 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0018] Preparation of sample example 3: Prepare solution A, add 1.0 ml of oleic acid to 35 ml of ethanol, stir at 70°C for 30 minutes, then drop a deionized aqueous solution of a mixture of sodium fluoride and ammonium fluoride, the analytical purity of sodium fluoride and ammonium fluoride is 99.8%, and stir while dropping until the pH value is 5, and keep 70°C during the dropping process; Step (2), prepare solution B, add 1.8 ml of 2-enoyl trifluoroacetate to 35 ml of ethanol, stir at 70°C for 40 minutes, then add 0.035 mmol of europium oxide and 1.2 mmol of lanthanum nitrate, europium oxide and nitric acid. The analytical purity of lanthanum is 99.8%, and it is stirred at 70°C for 2.5 hours; step (3), solution B is added dropwise to solution A, stirring while adding dropwise, and the temperature is maintained at 70°C; step (4), the mixed solution of step (3) is poured into a reactor, the temperature of the reactor is 135°C, and maintained for 13 hours; step (5), after the reactor is naturally cooled, the reactant of step (4) is taken out, centrifuged and washed with deionized water, and the supernatant is removed, and the treatment is performed 4 times; step (6), the product of step (5) is placed in a vacuum environment at 40°C, and dried for 14 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0019] Preparation of sample example 4: Prepare solution A, add 0.8 ml of oleic acid to 30 ml of ethanol, stir at 70°C for 40 minutes, then add deionized ammonium fluoride solution dropwise, the analytical purity of ammonium fluoride is 99.8%, stir while adding dropwise until the pH value is 6, and keep 70°C during the addition process; Step (2), prepare solution B, add 2.0 ml of a mixture of acetylacetone and methyl acetoacetate to 40 ml of ethanol, stir at 80°C for 30 minutes, then add 0.06 mmol of europium nitrate and 0.7 mmol of lanthanum oxide, the analytical purity of europium nitrate and lanthanum oxide ... and the analytical purity of europium nitrate and lanthanum oxide is 99.8%. The purity is 99.8%, and it is stirred at 80°C for 2.5 hours; step (3), solution B is added dropwise to solution A, stirring while adding dropwise, and the temperature is maintained at 80°C; step (4), the mixed solution of step (3) is poured into a reactor, the temperature of the reactor is 130°C, and maintained for 13 hours; step (5), after the reactor is naturally cooled, the reactant of step (4) is taken out, centrifuged and washed with deionized water, and the supernatant is removed, and the treatment is repeated 5 times; step (6), the product of step (5) is placed in a vacuum environment of 50°C and dried for 14 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0020] Preparation of Sample Example 5: Prepare Solution A by adding 1.0 ml of oleic acid to 30 ml of ethanol, stirring at 70°C for 30 minutes, then dropwise adding a deionized aqueous solution of sodium fluoride, the analytical purity of which is 99.8%, while stirring until the pH value is 5.5, and keep the temperature at 70°C during the dropping process; Step (2), prepare Solution B by adding 1.5 ml of a mixture of acetylacetone and 2-enoyl trifluoroacetate to 35 ml of ethanol, stirring at 70°C for 30 minutes, then adding 0.03 mmol of europium oxide and 0.5 mmol of lanthanum oxide, europium oxide and lanthanum oxide. The analytical purity of lanthanum is 99.8%, and it is stirred at 80°C for 2 hours; step (3), solution B is added dropwise to solution A, stirring while adding dropwise, and the temperature is maintained at 80°C; step (4), the mixed solution of step (3) is poured into a reactor, the temperature of the reactor is 130°C, and maintained for 13 hours; step (5), after the reactor is naturally cooled, the reactant of step (4) is taken out, centrifuged and washed with deionized water, and the supernatant is removed, and the treatment is performed 5 times; step (6), the product of step (5) is placed in a vacuum environment of 50°C, and dried for 13 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0021] Preparation of Sample Example 6: Prepare Solution A by adding 1.2 ml of oleic acid to 40 ml of ethanol, stirring at 70° C. for 40 minutes, then dropwise adding a deionized aqueous solution of a mixture of sodium fluoride and ammonium fluoride, wherein the analytical purity of the sodium fluoride and ammonium fluoride is 99.8%, and stirring while dropping until the pH value is 5.5, and maintaining 70° C. during the dropping process; Step (2), prepare Solution B by adding 2.0 ml of a mixture of acetylacetone, methyl acetoacetate and 2-enoyl trifluoroacetate to 45 ml of ethanol, stirring at 75° C. for 45 minutes, and then adding 0.02 mmol each of europium oxide and europium nitrate, and 0.4 mmol each of lanthanum oxide and lanthanum nitrate; mmol, the analytical purity of europium oxide, europium nitrate, lanthanum oxide and lanthanum nitrate is 99.8%, and it is stirred at 80°C for 3 hours; step (3), solution B is added dropwise to solution A, stirring while adding dropwise, and the temperature is maintained at 80°C; step (4), the mixed solution of step (3) is poured into a reactor, the temperature of the reactor is 130°C, and maintained for 13 hours; step (5), after the reactor is naturally cooled, the reactant of step (4) is taken out, centrifuged and washed with deionized water, and the supernatant is removed, and the treatment is performed 5 times; step (6), the product of step (5) is placed in a vacuum environment at 50°C, and dried for 13 hours to obtain a red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

[0022] Experimental Example: The present invention uses the sample prepared in Sample Example 1 as an example for experimental measurement. Figure 1Under the same measurement conditions, the samples prepared by the present invention were excited by an excitation light wave of 375 nanometers. The relative intensity of orange light was 5693, and the intensity of red light was 14327. The relative intensity of orange light was 429, and the intensity of red light was 142 for the samples without organic ligands and oleic acid. Calculations show that the relative intensity ratio of red fluorescence to orange fluorescence of the samples prepared by the present invention is 2.517, and the relative intensity ratio of red fluorescence to orange fluorescence of the samples without organic ligands and oleic acid is 0.331. The two relative intensity ratios are increased by 7.6 times. The energy of the samples prepared by the present invention is concentrated on the excitation of red fluorescence, and the luminous intensity of red light is increased by more than 100 times.

[0023] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A red phosphor of europium ion-doped lanthanum fluoride nanoparticles, Features The method for preparing red fluorescent powder comprises the following steps: Step (1), preparing solution A, adding oleic acid to ethanol, the volume ratio of oleic acid to ethanol is 1:20-60, stirring at 60-80°C for 20-40 minutes, and then dropping a deionized water solution containing a fluoride source, stirring while dropping, so that the pH value is in the range of 4-6, and continuing to maintain 60-80°C during the dropping process; Step (2), preparing solution B, adding an organic substance containing a β-diketonate organic ligand to ethanol, wherein the volume ratio of the organic substance containing a β-diketonate organic ligand to ethanol is 1:10-30, stirring at 60-80° C. for 20-40 minutes, then adding a europium source and a lanthanum source, and stirring at 60-80° C. for 1-3 hours; Step (3), adding solution B dropwise to solution A, stirring while adding dropwise, while maintaining the temperature at 60-80° C.; Step (4), pouring the mixed solution of step (3) into a reaction kettle at a temperature of 110-140° C. and maintaining the temperature for 10-14 hours; Step (5), after the reactor is cooled naturally, the reactant of step (4) is taken out, centrifuged with a centrifuge, the supernatant is removed, and the precipitate is washed with deionized water, and the treatment is repeated 3-5 times; Step (6), placing the product of step (5) in a vacuum environment at 40-60° C. and drying for 10-14 hours to obtain red phosphor of europium ion-doped lanthanum fluoride nanoparticles.

2. The red phosphor of europium ion-doped lanthanum fluoride nanoparticles according to claim 1, Features The fluoride source in step (1) is sodium fluoride or ammonium fluoride or a mixture of the two, and the analytical purity is ≥99.7%.

3. The red phosphor of europium ion-doped lanthanum fluoride nanoparticles according to claim 1, Features The organic substance containing the β-diketonate organic ligand in step (2) is acetylacetone, methyl acetoacetate or 2-enoyl trifluoroacetate or a mixture of two or three thereof.

4. The red phosphor of europium ion-doped lanthanum fluoride nanoparticles according to claim 1, Features The europium source in step (2) is europium nitrate or europium oxide or a mixture of the two, with an analytical purity of ≥99.7%, and the concentration of europium ions in ethanol is 0.0008-0.0025 mmol / ml.

5. The red fluorescent powder of europium ion doped lanthanum fluoride nanoparticles according to claim 1, Features The lanthanum source in step (2) is lanthanum oxide or lanthanum nitrate or a mixture of the two, with an analytical purity of ≥99.7%, and the concentration of lanthanum ions in ethanol is 0.015-0.055 mmol / ml.

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