Preparation method of single-component rare earth fluorescent powder

Abstract

The invention relates to a preparation method of single-component rare earth fluorescent powder, which comprises the following steps of: mixing yttrium chloride, europium chloride and terbium chloride serving as rare earth raw materials in proportion, preparing a ligand solution, dripping the ligand solution into a rare earth mixed solution, and coprecipitating to obtain the rare earth fluorescent powder. The preparation method is easy and convenient to operate and simple in process, the obtained fluorescent powder is uniform in ligand structure, few in impurity, high in color purity and high in luminous efficiency, meanwhile, the proportion of rare earth raw materials can be adjusted according to actual requirements, fluorescent powder with different colors is obtained, and the color gamut of the product is wide. The method is an ideal method for preparing the rare earth fluorescent powder.

Description

Technical Field

[0001] The invention relates to the field of luminescent material synthesis, in particular to a method for preparing a single-component rare earth phosphor. Background Art

[0002] At present, LED lamps with rare earth phosphors as the core luminescent material have become the fourth generation of lighting sources because of their good color reproduction, high efficiency and energy saving, green environmental protection, and long service life. Compared with fluorescent lamps made of rare earth tri-color phosphors, the luminous efficiency of LED lamps made of rare earth phosphors can reach 50-200lm / w, which is nearly 4 times higher. Therefore, the market demand for rare earth phosphors is increasing and the requirements are getting higher and higher.

[0003] Existing LED lamps generally use the "light-emitting chip + phosphor" method to achieve color display. Due to the high cost and immature technology of ultraviolet chips, they have not been widely used. Therefore, the existing chips are generally blue light-emitting chips, which have higher luminous efficiency. Among them, the commonly used rare earth phosphor preparation processes include high-temperature solid phase method, solution-gel method, combustion method, chemical precipitation method, etc., but different methods have certain defects. The high-temperature solid phase method is easy to mass produce, but has high requirements for raw materials and production equipment; the solution gel method has good reaction activity, but the preparation process is highly toxic and the yield is low; the combustion method has a short reaction time and simple operation, but the product luminescence performance is slightly poor; although the chemical precipitation method has better product quality, the process is complex and not conducive to mass production.

[0004] CN102827599B discloses a method for preparing a red, green and blue blended white light phosphor, which uses europium chloride, terbium chloride and beryllium sulfate as raw materials, needs to first prepare red, green and blue rare earth complexes, and then prepare red, green and blue monochrome polymer blends, and obtain white light phosphors by chemical precipitation. The disadvantage is that the ligands of different rare earth complexes are different, which will affect the luminous effect, and the preparation process is complicated, the steps are complicated, and it is not suitable for large-scale production. Therefore, there is still a lot of room for optimization in preparing rare earth phosphors by chemical precipitation. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing a single-component rare earth phosphor. By means of a coprecipitation method, the process flow of preparing rare earth phosphor by chemical precipitation is simplified. The ligand structure of the rare earth phosphor is single, and the product has few impurities, which is beneficial to improving the luminous effect of the product. At the same time, the proportion of rare earth compounds can be adjusted according to actual needs to obtain phosphors with different color development. Compared with other phosphors, this product is easier to prepare and has a wider range of applications.

[0006] A method for preparing a single-component rare earth phosphor, characterized in that it comprises the following steps:

[0007] Evenly mix yttrium chloride, europium chloride and terbium chloride to obtain a mixed solution;

[0008] adding the mixed solution while stirring the ligand solution to obtain a reaction solution;

[0009] Adjusting the pH value of the reaction solution to 6-8 is conducive to promoting the rightward shift of the reaction equilibrium and completely precipitating the rare earth complex;

[0010] Heating the reaction solution at 78-82°C for 2-2.5 hours. Heating the reaction solution at 80°C is beneficial to improving the reaction activity, fully reacting, and increasing the yield of the rare earth complex. At the same time, it can effectively remove the residual catalyst in the ligand.

[0011] The reaction solution was cooled to below 30°C, allowed to stand, and filtered to obtain a rare earth complex;

[0012] The solid product is washed with deionized water for 3-4 times and dried to obtain a single-component rare earth phosphor.

[0013] Preferably, the molar ratio of yttrium chloride, europium chloride and terbium chloride is x:y:z, wherein x+y+z=1, x, y and z are all non-negative rational numbers less than or equal to 1, and the molar ratio of yttrium chloride, europium chloride and terbium chloride can be adjusted according to the color rendering requirements, and different ratios will affect the luminous effect of the final phosphor product.

[0014] Preferably, the ligand is a dialkoxy terephthalic acid compound, wherein the alkyl group is one or two of methyl, ethyl, phenyl, benzyl, butyl, cyclohexyl, and isooctyl, and the ligand has a single structure, thereby avoiding the influence of impurities on the luminescence properties of the phosphor.

[0015] Preferably, the ligand preparation comprises the following steps:

[0016] A mixture of dihydroxyterephthalic acid and 200 mL of methanol is placed in an environment of 0-4°C, thionyl chloride is added, and the mixture is heated to 78°C and stirred for reaction for 4-4.5 hours to obtain system 1. The reaction at 78°C can avoid the volatilization of the catalyst thionyl chloride, and the reaction within 4.5 hours can avoid the increase of the reverse reaction leading to the reduction of dihydroxyterephthalic acid methyl ester;

[0017] Concentrate system 1 until solid appears, filter and obtain methyl dihydroxy terephthalate;

[0018] Methyl dihydroxyterephthalate, 30 mL of N,N-dimethylformamide, potassium carbonate, and alkyl halide are mixed, placed in an inert gas environment, heated to above 100°C, and stirred for reaction for 7.5-8 hours to obtain system 2. The hydroxyl group and alkyl halide in this step undergo a substitution reaction, and the reaction activity of both is low. Therefore, the reaction is catalyzed by high temperature heating (above 100°C) and adding potassium carbonate, and the reaction time is longer to make the reaction more complete;

[0019] Add water to system 2 until solid appears, cool to -12-15°C, filter, and obtain dialkoxy terephthalic acid methyl ester compounds. Freeze filtration can precipitate, agglomerate, and precipitate impurities whose solubility is reduced at low temperatures, such as inorganic products, to facilitate impurity removal and reduce the loss of effective ingredients.

[0020] Mix a dialkoxy terephthalic acid methyl ester compound, sodium hydroxide, and 80 mL of water, heat to 100° C. in an inert gas environment, and stir to react for 2.5-3 hours to obtain system 3. Sodium hydroxide introduces sodium ions into the dialkoxy terephthalic acid methyl ester compound, increases the solubility and stability of the compound in water, and prepares for subsequent acidification;

[0021] Add hydrochloric acid to system 3 until the pH is 2, cool to room temperature, and filter to obtain a dialkoxy terephthalic acid compound. Acidification with hydrochloric acid is beneficial to a full reaction and removes the alkaline cosolvent and catalyst at the same time.

[0022] Preferably, the alkyl group of the alkyl halide includes one of methyl, ethyl, phenyl, benzyl, butyl, cyclohexyl and isooctyl, and the halogen atom includes one of chlorine, bromine and iodine.

[0023] Preferably, the molar ratio of dihydroxyterephthalic acid to thionyl chloride in the system 1 is 1:2-2.25.

[0024] Preferably, the molar ratio of dihydroxyterephthalate, potassium carbonate and alkyl halide in the system 2 is 1:2.6:2.5-2.6.

[0025] Preferably, the molar ratio of the dialkoxy methyl terephthalate compound to sodium hydroxide in the system 3 is 1:4.

[0026] Preferably, the ligand solution contains sodium hydroxide solution, and the pH of the ligand solution is 6-8. Sodium hydroxide helps the ligand to dissolve in water. Adjusting the pH to neutral can avoid decomposition of the ligand during the dissolution process and reduce the ligand content.

[0027] Preferably, the mass ratio of the ligand solution to the mixed solution is 60-70:30-40.

[0028] Compared with the prior art, the beneficial effect of the present invention is that yttrium chloride, europium chloride, and terbium chloride are mixed in proportion in advance and added to the ligand solution, and a precipitate, i.e., a rare earth complex, can be obtained under low temperature (≤100°C). First, the rare earth complex prepared by this method has a unified structure, high particle uniformity, and high physical purity of the product, which avoids the influence of impurities on the luminous effect of the product. Second, the present invention can adjust the molar ratio of yttrium chloride, europium chloride, and terbium chloride according to actual needs, so that the product can obtain different color-developing luminous effects, and achieve the purpose of adjusting the color coordinates, color gamut, and brightness of the product. Third, compared with the existing preparation of rare earth complexes corresponding to blue, green, and red light separately, and then making corresponding monochrome polymers, and then mixing and processing them into fluorescent powder, the present invention greatly simplifies the process of preparing fluorescent powder, has strong practicality, saves production costs, and is of great significance to promoting the large-scale production of fluorescent powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] In the attached figure:

[0032] Figure 1 : Schematic diagram of the chemical reaction principle for ligand preparation, wherein compound 1 is dihydroxyterephthalic acid, compound 2 is dihydroxyterephthalic acid methyl ester, compound 3 is a dialkoxyterephthalic acid methyl ester compound, compound 4 is a dialkoxyterephthalic acid compound, and the R group is one of methyl, ethyl, phenyl, benzyl, butyl, cyclohexyl, and isooctyl.

[0033] Figure 2 : Excitation spectrum and emission spectrum of rare earth phosphor I.

[0034] Figure 3 : Excitation and emission spectra of yttrium complexes.

[0035] Figure 4 : Excitation and emission spectra of europium complexes.

[0036] Figure 5 : Excitation and emission spectra of terbium complexes.

[0037] Figure 6 : Spectrum and chromaticity diagram of rare earth phosphor II.

[0038] Figure 7 : Spectrum and chromaticity diagram of rare earth phosphor III.

[0039] Figure 8 : Spectrum and chromaticity diagram of rare earth phosphor IV.

[0040] Fig. 9 : Spectrum and chromaticity diagram of rare earth phosphor V. DETAILED DESCRIPTION

[0041] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention all belong to the scope of protection of the present invention. Unless otherwise specified, the experimental materials, reagents, instruments, etc. used in the examples of the present invention are all commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0042] Example 1 Preparation of 2,5-dimethoxyterephthalic acid ligand solution

[0043] A mixture of 50 g (252 mmol) of 2,5-dihydroxyterephthalic acid and 200 mL of methanol was placed in an ice bath, 40 mL (550 mmol) of thionyl chloride was slowly added dropwise, and the mixture was slowly heated to 78°C and stirred for 4 hours to obtain system 1;

[0044] System 1 was concentrated until solid appeared, and after cooling to room temperature, it was filtered to obtain methyl 2,5-dihydroxyterephthalate with a reaction yield of 93%;

[0045] 5 g (20 mmol) of methyl 2,5-dihydroxyterephthalate, 30 mL of N,N-dimethylformamide, 8 g (58 mmol) of potassium carbonate, and 7 g (50 mmol) of methyl iodide were mixed, placed in a nitrogen environment, slowly heated to 100° C., and stirred for reaction for 8 hours to obtain system 2;

[0046] Add water to system 2 until solid appears, cool to -12-15°C, filter, and obtain methyl 2,5-dimethoxyterephthalate compounds with a reaction yield of 88%;

[0047] 15 g (62.5 mmol) of methyl 2,5-dimethoxyterephthalate compound, 10 g (250 mmol) of sodium hydroxide, and 80 mL of water were mixed, heated to 100° C. in a nitrogen environment, and stirred for reaction for 3 hours to obtain system 3;

[0048] Hydrochloric acid was added to system 3 until the pH value was 2, the mixture was cooled to room temperature, and filtered to obtain 2,5-dimethoxyterephthalic acid with a reaction yield of 90%.

[0049] 2 g of 2,5-dimethoxyterephthalic acid and 100 mL of water were mixed, and 10% sodium hydroxide solution was added dropwise while stirring until the 2,5-dimethoxyterephthalic acid solid was completely dissolved, and then dilute hydrochloric acid was added dropwise to adjust the pH to 7 to obtain a 2,5-dimethoxyterephthalic acid ligand solution.

[0050] Example 2 Preparation of 2,5-dibenzyl ether terephthalic acid ligand solution

[0051] 5 g (20 mmol) of methyl 2,5-dihydroxyterephthalate prepared in Example 1 was mixed with 30 mL of N,N-dimethylformamide, 8 g (58 mmol) of potassium carbonate, and 6.5 g (51 mmol) of benzyl chloride, placed in a nitrogen environment, slowly heated to 100° C., and stirred for reaction for 8 hours to obtain System 2;

[0052] Add water to system 2 until solid appears, cool to -12-15°C, filter, and obtain 2,5-dibenzyl ether methyl terephthalate compounds with a reaction yield of 88%;

[0053] 12 g (30 mmol) of methyl 2,5-dibenzyl ether terephthalate compound, 4.8 g (120 mmol) of sodium hydroxide, and 80 mL of water were mixed, heated to 100° C. in a nitrogen environment, and stirred for reaction for 3 hours to obtain system 3;

[0054] Hydrochloric acid was added to system 3 until the pH value was 2, the mixture was cooled to room temperature, and filtered to obtain 2,5-dibenzyl ether terephthalic acid with a reaction yield of 90%.

[0055] Mix 2 g of 2,5-dibenzyl ether terephthalic acid and 100 mL of water, add 10% sodium hydroxide solution dropwise while stirring until the 2,5-dibenzyl ether terephthalic acid solid is completely dissolved, and then add dilute hydrochloric acid dropwise to adjust the pH to 7 to obtain a 2,5-dibenzyl ether terephthalic acid ligand solution.

[0056] Example 3 Preparation of rare earth phosphor I

[0057] Yttrium chloride, europium chloride and terbium chloride are mixed in a molar ratio of 0.96:0.02:0.02 to obtain a rare earth compound mixed solution;

[0058] Take the 2,5-dibenzyl ether terephthalic acid ligand solution of Example 2, and add the 2,5-dibenzyl ether terephthalic acid ligand solution dropwise to the rare earth compound mixed solution while stirring. After the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0059] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0060] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain rare earth phosphor I.

[0061] Example 4 Preparation of yttrium complex

[0062] Take the 2,5-dibenzyl ether terephthalic acid ligand solution of Example 2, add the 2,5-dibenzyl ether terephthalic acid ligand solution dropwise to the yttrium chloride solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0063] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0064] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain a yttrium complex.

[0065] Example 5 Preparation of Europium Complex

[0066] Take the 2,5-dibenzyl ether terephthalic acid ligand solution of Example 2, add the 2,5-dibenzyl ether terephthalic acid ligand solution dropwise to the europium chloride solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0067] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0068] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain a europium complex.

[0069] Example 6 Preparation of Terbium Complex

[0070] Take the 2,5-dibenzyl ether terephthalic acid ligand solution of Example 2, add the 2,5-dibenzyl ether terephthalic acid ligand solution dropwise to the terbium chloride solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0071] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0072] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain a terbium complex.

[0073] Example 7 Preparation of rare earth phosphor II

[0074] Yttrium chloride, europium chloride and terbium chloride are mixed in a molar ratio of 0.98:0.01:0.01 to obtain a rare earth compound mixed solution;

[0075] Take the 2,5-dialkoxy terephthalic acid ligand solution of Example 1, add the 2,5-dialkoxy terephthalic acid ligand solution dropwise to the rare earth compound mixed solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0076] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0077] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain rare earth phosphor II.

[0078] Example 8 Preparation of Rare Earth Phosphor III

[0079] Yttrium chloride, europium chloride and terbium chloride are mixed in a molar ratio of 0.954:0.045:0.01 to obtain a rare earth compound mixed solution;

[0080] Take the 2,5-dialkoxy terephthalic acid ligand solution of Example 1, add the 2,5-dialkoxy terephthalic acid ligand solution dropwise to the rare earth compound mixed solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0081] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0082] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain rare earth phosphor III.

[0083] Example 9 Preparation of rare earth phosphor IV

[0084] Yttrium chloride, europium chloride and terbium chloride are mixed in a molar ratio of 0.93:0.04:0.03 to obtain a rare earth compound mixed solution;

[0085] Take the 2,5-dialkoxy terephthalic acid ligand solution of Example 1, add the 2,5-dialkoxy terephthalic acid ligand solution dropwise to the rare earth compound mixed solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0086] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0087] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain rare earth phosphor IV.

[0088] Example 10 Preparation of rare earth phosphor V

[0089] Yttrium chloride, europium chloride and terbium chloride are mixed in a molar ratio of 0.905:0.043:0.057 to obtain a rare earth compound mixed solution;

[0090] Take the 2,5-dialkoxy terephthalic acid ligand solution of Example 1, add the 2,5-dialkoxy terephthalic acid ligand solution dropwise to the rare earth compound mixed solution while stirring, and after the addition is completed, adjust the pH of the reaction system to 7 with dilute hydrochloric acid to precipitate the rare earth complex;

[0091] The reaction system was heated to 80°C and reacted for 2 hours. After the reaction was completed, the system was slowly cooled to room temperature, allowed to stand, and filtered to obtain a rare earth complex.

[0092] The rare earth complex is washed with deionized water for 3-4 times and dried to obtain rare earth phosphor V.

[0093] Experimental Example Preparation of Spectra of Rare Earth Phosphors and Rare Earth Complexes

[0094] The excitation light wavelength was set to 365 nm and 395 nm, and the excitation spectrum (EX) and emission spectrum (EM) of the rare earth phosphor I at room temperature were measured using a fluorescence spectrometer.

[0095] The excitation spectra (EX) and emission spectra (EM) of yttrium complex, europium complex and terbium complex at room temperature were measured by fluorescence spectrometer.

[0096] The fluorescence intensity of rare earth phosphors II, III, IV, and V under excitation light of different wavelengths at room temperature was measured using a fluorescence spectrometer. The color coordinates were calculated based on the spectral data of the samples, and the chromaticity diagram was drawn using CIE1931 color coordinate software.

[0097] Depend on Figure 2 It can be seen that the fluorescence intensity of rare earth phosphor I (2,5-dibenzyl ether-1,6-phthalic acid-Y0.96-Eu0.02-Tb0.02) is the highest at 260-270nm. When rare earth phosphor I is excited by 395nm near-ultraviolet light and 365nm ultraviolet light, it shows blue light. This shows that the rare earth phosphor of this product can meet the requirements of ultraviolet excitation in addition to the common blue light excitation conditions, and can be used for the preparation of "ultraviolet light-emitting chip + phosphor" luminescent LED lamps.

[0098] Depend on Figure 3 It can be seen that the fluorescence intensity of the yttrium complex (2,5-dibenzyl ether-1,6-phthalic acid 3-Y2) is the highest at 270-280nm, and the emission spectrum (EM) shows that the yttrium complex emits blue light.

[0099] Depend on Figure 4It can be seen that the fluorescence intensity of the europium complex (2,5-dibenzyl ether-1,6-phthalic acid 3-Eu2) is the largest at 340-350nm, and the emission spectrum (EM) shows that the europium complex emits red light.

[0100] Depend on Figure 5 It can be seen that the fluorescence intensity of the terbium complex (2,5-dibenzyl ether-1,6-phthalic acid 3-Tb2) is the largest at 320-350nm, and the emission spectrum (EM) shows that the terbium complex emits green light.

[0101] Depend on Figure 6 It can be seen that the fluorescence spectrum (intensity / au represents light intensity, wavelength / nm represents wavelength) shows that blue light accounts for the largest proportion in the emission light of rare earth phosphor II, with a small amount of red light. The chromaticity diagram shows that the phosphor is dark blue, and its color coordinates are (x=0.194, y=0.108).

[0102] Depend on Figure 7 It can be seen that as the molar amount of red-emitting europium chloride increases, the fluorescence spectrum (intensity / au represents light intensity, wavelength / nm represents wavelength) shows that red light accounts for the largest proportion in the emission light of the rare earth phosphor III, and the chromaticity diagram shows that the phosphor is rose red, and its color coordinates are (x=0.398, y=0.261).

[0103] Depend on Figure 8 It can be seen that as the molar amount of terbium chloride emitting green light increases, the fluorescence spectrum (intensity / au represents light intensity, wavelength / nm represents wavelength) shows that blue light accounts for the largest proportion in the emission light of rare earth phosphor IV, and the chromaticity diagram shows that the phosphor is cyan, and its color coordinates are (x=0.252, y=0.306).

[0104] Depend on Fig. 9 It can be seen that by gradually adjusting the proportion of rare earth compounds, the fluorescence spectrum (intensity / au represents light intensity, wavelength / nm represents wavelength) shows that the proportions of blue light, red light and green light in the emission light of the rare earth phosphor V are basically close, and the chromaticity diagram shows that the phosphor is nearly white, and its color coordinates are (x=0.357, y=0.328), which is close to the color coordinate center of white light (x=0.333, y=0.333).

[0105] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for preparing a single-component rare earth phosphor, characterized in that: The following steps are involved: Evenly mix yttrium chloride, europium chloride and terbium chloride to obtain a mixed solution; adding the mixed solution while stirring the ligand solution to obtain a reaction solution; Adjust the pH value of the reaction solution to 6-8, and heat the reaction solution at 78-82°C for 2-2.5 hours; The reaction solution was cooled to below 30°C, allowed to stand, and filtered to obtain a rare earth complex; The solid product is washed with deionized water for 3-4 times and dried to obtain a single-component rare earth phosphor.

2. The preparation method according to claim 1, characterized in that: The molar ratio of yttrium chloride, europium chloride and terbium chloride is x:y:z, wherein x+y+z=1, and x, y and z are all non-negative rational numbers less than or equal to 1.

3. The preparation method according to claim 1, characterized in that: The ligand is a dialkoxy terephthalic acid compound, wherein the alkyl group is one or two of methyl, ethyl, phenyl, benzyl, butyl, cyclohexyl and isooctyl.

4. The preparation method according to claim 3, characterized in that: The ligand preparation comprises the following steps: The mixture of dihydroxyterephthalic acid and methanol is placed in an environment of 0-4°C, thionyl chloride is added, and the mixture is heated to 78°C and reacted for 4-4.5 hours to obtain system 1; Concentrate system 1 until solid appears, filter and obtain methyl dihydroxy terephthalate; Methyl dihydroxyterephthalate, N,N-dimethylformamide, potassium carbonate and alkyl halide are mixed, placed in an inert gas environment, heated to above 100° C., and reacted for 7.5-8 hours to obtain system 2; Add water to system 2 until solid appears, cool to -12--15°C, filter, and obtain dialkoxy terephthalic acid methyl ester compounds; Mix a dialkoxy terephthalic acid methyl ester compound, sodium hydroxide and water, heat to 100° C. in an inert gas environment, and react for 2.5-3 hours to obtain system 3; Add hydrochloric acid to the system 3 until the pH is 2, cool to room temperature, and filter to obtain a dialkoxy terephthalic acid compound.

5. The preparation method according to claim 4, characterized in that: The alkyl group of the alkyl halide includes one of methyl, ethyl, phenyl, benzyl, butyl, cyclohexyl and isooctyl, and the halogen atom includes one of chlorine, bromine and iodine.

6. The preparation method according to claim 4, characterized in that: The molar ratio of dihydroxyterephthalic acid to thionyl chloride in the system 1 is 1:2-2.

25.

7. The preparation method according to claim 4, characterized in that: The molar ratio of dihydroxyterephthalate, potassium carbonate and alkyl halide in the system 2 is 1:2.6:2.5-2.

6.

8. The preparation method according to claim 4, characterized in that: The molar ratio of the dialkoxy terephthalic acid methyl ester compound to sodium hydroxide in the system 3 is 1:

4.

9. The preparation method according to claim 1, characterized in that: The ligand solution contains sodium hydroxide solution, and the pH value of the ligand solution is 6-8.

10. The preparation method according to claim 1, characterized in that: The mass ratio of the ligand solution to the mixed solution is 60-70:30-40.

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