CN114774115B - LED fluorescent powder and preparation method and application thereof - Google Patents

Abstract

The invention discloses an LED phosphor, its preparation method and application, and belongs to the technical field of material synthesis; the structural formula of the LED phosphor provided by the invention is A ₂ (MF ₆ ):Mn ⁴⁺ , and its D ₅₀ =3.5 ‑21.5μm, D ₁₀ ≥1.0μm, D ₉₀ ≤31.65μm, particle size distribution coefficient P=(D ₉₀ ‑D ₁₀ )/D ₅₀ ≤1.0; where, A includes Li, Na, K, Rb, Cs, NH ₄ Any one of them, M includes any one of Ge, Si, Sn, Ti, Zr, Sc; its preparation method is: the hydrofluoric acid solution of fluorosilicate and the hydrofluoric acid of hexafluoromanganate The acid solution is ultrasonically stirred, and the hydrofluoric acid solution of hydrogen fluoride salt is added dropwise. After the dropwise addition, ultrasonically stirred for crystallization, quenching, aging, washing, and drying to obtain LED fluorescent powder; the invention synthesizes fluorescent powder through chemical liquid phase ultrasonic , ultrasonic waves are introduced in the preparation process, and aging steps are taken in the follow-up, so as to obtain phosphor powder with uniform small particle size distribution; the preparation method of the present invention has high yield and simple operation, and the phosphor powder can be applied to LED products to improve light emission. Efficiency and light quality, and save package usage.

Description

LED phosphor and its preparation method and application

Technical Field

The invention belongs to the technical field of material synthesis, and in particular relates to an LED phosphor and a preparation method and application thereof.

Background Art

LED phosphors can improve the light quality and color rendering of LED products. Therefore, improving the luminous efficiency of LED packaging devices, improving light color quality, and reducing packaging costs through LED phosphor technology innovation is the eternal theme of LED phosphor technology development.

At present, the particle size of the fluoride LED red phosphors that are mass-produced or reported on the market is generally between 18-45μm, and there is no phosphor with a smaller particle size; at the same time, the fluoride LED red phosphors currently commercially available on the market are all synthesized using a chemical precipitation method, and because the fluoride LED red phosphor crystals are extremely easy to grow, it is difficult to control the powder particle size below 20μm using the current preparation method; in current industrial production, a liquid phase synthesis process is used to synthesize fluoride LED red phosphors, but the particle size of the powder synthesized by this method generally fluctuates between 4-8μm, resulting in insufficient particle size concentration. If further processed by screening, part of the yield will be sacrificed.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an LED phosphor with small particle size and high particle size concentration, and a preparation method and application thereof.

To achieve the above object, the technical solution adopted by the present invention is: an LED phosphor, the structural formula of the LED phosphor is _A2 ( _MF6 ):Mn4 ⁺ , its _D50 =3.5-21.5μm, _D10≥1.0μm , _{D90≤31.65μm} , and particle size distribution coefficient P=( _D90 - _D10 ) _/D50≤1.0 ; wherein A includes any one of Li, Na, K, Rb, Cs, and _NH4 , and M includes any one of Ge, Si, Sn, Ti, Zr, and Sc.

The technical solution of the present invention provides an LED phosphor with small particle size and concentrated particle size distribution, which can be well applied to LED products and has excellent improvement effect on the light efficiency and light quality of LED products.

As a preferred embodiment of the LED phosphor of the present invention, the structural formula of the LED phosphor is K ₂ Si _(1-x) F ₆ :Mn _x , wherein x=0.045-0.070.

In addition, the present invention also provides a method for preparing LED phosphor, comprising the following steps:

(1) adding a hydrofluoric acid solution of fluorosilicate to a hydrofluoric acid solution of hexafluoromanganate, stirring and mixing, to obtain a mixed solution;

(2) placing the mixed solution under ultrasonic stirring at 2-10° C. and adding dropwise a hydrofluoric acid solution of a hydrofluoride salt;

(3) After the dropwise addition is completed, ultrasonic stirring is performed for crystallization, reaction is quenched, aging is performed, washing is performed, and drying is performed to obtain LED phosphor.

The invention prepares LED fluorescent powder by a chemical liquid phase ultrasonic stirring synthesis method. In the preparation process, ultrasonic waves of a specific frequency are introduced to effectively inhibit the characteristic that crystals of the fluorescent powder are easy to grow, thereby preparing fluorescent powder with small particle size. In the chemical liquid phase ultrasonic stirring synthesis process, the crystal formation of the LED fluorescent powder generally includes two stages, one is the formation of crystal nuclei, and the other is the growth of crystal nuclei. Only when the rates of these stages are relatively balanced, the crystals of the prepared fluorescent powder will have smaller particle size and better distribution uniformity. The invention combines ultrasonic waves and dripping at a specific temperature to achieve a good balance between the formation of crystal nuclei and the growth of crystals, thereby achieving the purpose of synthesizing LED fluorescent powder with small particle size and high uniformity, wherein _D50 of the synthesized LED fluorescent powder is 3.5-21.5μm, and P is ( _D90 - _D10 ) _/D50≤1.0 .

As a preferred embodiment of the preparation method of the present invention, in the step (1), the temperature of the hydrofluoric acid solution of fluorosilicate and the hydrofluoric acid solution of hexafluoromanganate is 0-6°C.

As a preferred embodiment of the preparation method of the present invention, in the step (1), the mass volume ratio of hexafluoromanganate to hydrofluoric acid solution is (6-9) g:2.5L.

The mass-to-volume ratio of hexafluoromanganate to hydrofluoric acid solution can be used to adjust the concentration of tetravalent manganese ions in the luminescent center of the finished phosphor product, thereby adjusting the color coordinates, luminous intensity and the amount of powder used for packaging LED products of the phosphor. When the mass-to-volume ratio of the two is within the above range, the prepared LED phosphor has suitable color coordinates and luminous intensity, thereby reducing the packaging cost of subsequent applications.

As a preferred embodiment of the preparation method of the present invention, in the step (1), the fluorosilicate includes potassium fluorosilicate, sodium fluorosilicate, and ammonium fluorosilicate; and the hexafluoromanganate includes potassium hexafluoromanganate.

As a preferred embodiment of the preparation method of the present invention, in the step (1), the mass concentration of the hydrofluoric acid is 41-45%.

As a preferred embodiment of the preparation method of the present invention, in the step (1), the molar concentration of the solute in the hydrofluoric acid solution of the fluorosilicate is 1.3-1.8 mol/L.

As a preferred embodiment of the preparation method of the present invention, in the step (1), the stirring time is 1-4 minutes.

As a preferred embodiment of the preparation method of the present invention, in the step (2), the dropping speed is 2-10 mL/s.

As a preferred embodiment of the preparation method of the present invention, in the step (2), the dropping speed is 4-8 mL/s.

When the dropping speed is 2-10mL/s, especially 4-8mL/s, it can ensure that the formation points of the crystal nuclei are relatively dispersed, avoiding the formation of crystal nuclei clustering, resulting in larger crystal particle size in the later stage or decreased crystal dispersion uniformity; at the same time, it can reduce the impurities in the powder formation process, thereby ensuring the light efficiency of the prepared powder.

As a preferred embodiment of the preparation method of the present invention, in the step (2), the frequency of ultrasound is 5-50 kHz.

During the ultrasonic stirring process, the introduction of ultrasonic waves of the above-mentioned ultrasonic frequency can inhibit the excessive growth of the phosphor crystal nuclei, thereby ensuring the small particle size of the prepared phosphor; if the ultrasonic frequency is insufficient, the synthesized particle size will be too large; if the ultrasonic frequency is too high, the formed crystal nuclei will be destroyed, thereby failing to form a phosphor body with a certain shape and reducing the effect of subsequent applications.

As a preferred embodiment of the preparation method of the present invention, in the step (2), the molar concentration of the hydrofluoride salt in the hydrofluoric acid solution of the hydrofluoride salt is 1.8-2.2 mol/L.

As a preferred embodiment of the preparation method of the present invention, in the step (2), the molar concentration of the hydrofluoride salt in the hydrofluoric acid solution of the hydrofluoride salt is 2 mol/L.

Selecting the molar concentration within the above range for dropwise addition can be coordinated with the dropwise addition speed to ensure that the formation of crystal nuclei is relatively dispersed, and will not be too concentrated to cause the problem of excessively large crystal particles or decreased distribution uniformity due to the overlap of crystal nuclei in the later stage. It can also avoid the problem of increased impurities and decreased light efficiency caused by excessively high concentration of the added hydrogen fluoride salt.

As a preferred embodiment of the preparation method of the present invention, the mass ratio of the hydrogen fluoride salt to the fluoromanganate salt is (6-9):1.

As a preferred embodiment of the preparation method of the present invention, in the step (3), the frequency of ultrasound is 5-50 kHz; the temperature of crystallization is 2-10° C., and the time of crystallization is 8-12 min.

Maintaining the above-mentioned ultrasonic frequency, crystallization temperature and crystallization time during the crystallization stage can control the growth rate of the crystal nuclei formed in step (2), avoiding the formation of larger crystals or uneven particle size distribution of the formed crystals.

As a preferred embodiment of the preparation method of the present invention, in the step (3), the aging temperature is 2-10°C, and the aging time is 2-8 minutes.

Providing a suitable aging condition for the crystals after the quenching reaction and before washing can further improve the crystallinity of the particles, further concentrate the particle size distribution, and also ensure the crystallization yield.

As a preferred embodiment of the preparation method of the present invention, in the step (3), the quenching reaction is performed by adding hydrogen peroxide to the reaction system for quenching; the mass concentration of the hydrogen peroxide is 25-40%; and the amount of hydrogen peroxide added is sufficient to cause the system to change color.

As a preferred embodiment of the preparation method of the present invention, in the step (3), the solvent used for washing is acetone, and the end of washing is marked by the pH value of the system being 6.8-7.2.

As a preferred embodiment of the preparation method of the present invention, in the step (3), the drying method is vacuum drying, and the vacuum drying temperature is 70-90°C.

In addition, the present invention also provides application of the LED fluorescent powder in LED products.

Compared with the prior art, the present invention has the following beneficial effects:

First: The technical solution of the present invention provides an LED phosphor, whose D ₅₀ =3.5-21.5 μm, and particle size distribution coefficient P=(D ₉₀ -D ₁₀ )/D ₅₀ ≤1.0. Since the LED phosphor provided by the present invention has a narrow particle size distribution and high uniformity, it can provide excellent light efficiency and light quality for LED products, and at the same time, it can improve the packaging efficiency of LED products and reduce packaging costs;

Second: In the preparation process of the LED phosphor provided by the present invention, a chemical liquid phase ultrasonic stirring synthesis method is adopted, and at the same time, the dropwise mixing of the reaction raw materials, a specific mixing and crystallization temperature, and an appropriate crystallization time and subsequent aging time are coordinated, so that the rate of crystal nucleus formation and crystal growth in the process of crystal formation of the phosphor is relatively balanced, and the subsequent aging can further stabilize the crystal and narrow the particle size distribution range, thereby achieving the advantage of high particle size distribution concentration;

Third: In the preparation process of the LED phosphor provided by the present invention, ultrasound is introduced, and the power of ultrasound and the position and number of energy overflow ports in the preparation system are controlled to achieve different degrees of inhibition of crystal growth, thereby achieving the purpose of preparing phosphors in a specific small particle size range;

Fourth: The preparation process of the LED phosphor provided by the present invention is simple, easy to operate, and suitable for actual production.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a SEM image of the phosphor prepared in Example 1 of the present invention;

FIG2 is a SEM image of the phosphor prepared in Comparative Example 1 of the present invention;

FIG3 is an ultrasonic water bath temperature control device used in an embodiment of the present invention;

1-temperature-controlled circulating water outlet, 2-temperature-controlled circulating water outlet, 3-frequency-converting ultrasonic generator, 4-stirring paddle, 5-liquid feed inlet, 6-discharging port, 7-valve, 8-frequency-converting motor, 9-cooling water interlayer.

DETAILED DESCRIPTION

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

Example 1

The preparation method of the LED phosphor of the embodiment of the present invention is as follows:

(1) Preparation of potassium bifluoride hydrofluoric acid solution: Potassium bifluoride is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium bifluoride hydrofluoric acid solution, wherein the molar concentration of potassium bifluoride is 2 mol/L;

(2) Preparation of a potassium fluorosilicate hydrofluoric acid solution: Potassium fluorosilicate is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium fluorosilicate hydrofluoric acid solution, wherein the molar concentration of the potassium fluorosilicate is 1.5 mol/L;

(3) 2.5 L of hydrofluoric acid with a mass concentration of 41% was measured, 6 g of potassium fluoromanganate was added at 3° C., and the mixture was stirred for 2-4 min until the solid was completely dissolved, and then the mixture was added to 200 mL of potassium fluorosilicate hydrofluoric acid solution at 3° C., and stirred for 2-4 min to obtain a mixed solution;

(4) placing the mixed solution in step (3) in an ultrasonic water bath temperature control device (as shown in FIG. 3 ), controlling the water bath temperature at 6° C., turning on the stirring and ultrasonic generator at the same time, adjusting the ultrasonic frequency to 5 kHz, and after the temperature of the device stabilizes, starting to drop a hydrofluoric acid solution of potassium bifluoride at a temperature of 3° C., at a rate of 6.5 mL/s, and a drop volume of 400 mL. After the drop addition is completed, continue stirring the ultrasonic crystallization at this ultrasonic frequency for 10 min;

(5) After the crystallization is completed, add hydrogen peroxide with a mass concentration of 25% until the system changes color, then turn off the ultrasonic generator, control the water bath temperature to 6°C, and stir for 10 minutes;

(6) After aging, the mixture was washed with acetone until the system became neutral, filtered, and the solid was collected. The solid powder was dried at 80°C and then sieved to obtain LED phosphor. The structural formula of the LED phosphor is K ₂ Si _0.95 F ₆ :Mn _0.05 . The SEM image of the obtained LED phosphor is shown in FIG1 .

Example 2

The embodiment of the present invention explores the influence of the ultrasonic frequency in step (4). In this embodiment, 5 test cases are set. Except that the ultrasonic frequency in step (4) is inconsistent, the remaining operations are the same as those in Example 1. The ultrasonic frequencies of the test cases are shown in Table 1.

Table 1: Ultrasonic frequency table of test examples 1-5

Test Example 1 Test Example 2 Test Example 3 Test Example 4 Test Example 5 10kHz 20kHz 30kHz 40kHz 50kHz

Example 3

The embodiment of the present invention explores the influence of the addition amount of potassium fluoromanganate. In this embodiment, 3 test examples are set. Except for the different addition amounts of potassium fluoromanganate, the remaining operations are the same as those in Example 1. The potassium fluoromanganate of the test examples is shown in Table 2.

Table 2: Potassium Fluoromandate Addition Table of Test Examples 6-8

Test Example 6 Test Example 7 Test Example 8 7g 8g 9g

Example 4

The embodiment of the present invention explores the influence of the dropping speed. In this embodiment, 4 test examples are set. Except for the different dropping speeds, the rest of the operations are the same as those in Example 1. The potassium fluoromanganate of the test examples is shown in Table 3.

Table 3: Dropping rate table of test examples 9-12

Test Example 9 Test Example 10 Test Example 11 Test Example 12 2mL/s 4mL/s 8mL/s 10mL/s

Comparative Example 1

The preparation method of the LED phosphor of the comparative example of the present invention is as follows:

(1) Preparation of potassium bifluoride hydrofluoric acid solution: Potassium bifluoride is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium bifluoride hydrofluoric acid solution, wherein the molar concentration of potassium bifluoride is 2 mol/L;

(2) Preparation of a potassium fluorosilicate hydrofluoric acid solution: Potassium fluorosilicate is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium fluorosilicate hydrofluoric acid solution, wherein the molar concentration of the potassium fluorosilicate is 1.5 mol/L;

(3) 2.5 L of hydrofluoric acid with a mass concentration of 41% was measured, 6 g of potassium fluoromanganate was added at 3° C., and the mixture was stirred for 2-4 min until the solid was completely dissolved, and then the mixture was added to 200 mL of potassium fluorosilicate hydrofluoric acid solution at 3° C., and stirred for 2-4 min to obtain a mixed solution;

(4) placing the mixed solution in step (3) in a water bath temperature control device, the water bath temperature is controlled at 6°C, stirring is turned on, and after the temperature of the device stabilizes, potassium bifluoride hydrofluoric acid solution at a temperature of 3°C is added dropwise at a rate of 6.5 mL/s, and the volume added is 400 mL. After the addition is completed, stirring and crystallization is continued for 10 min;

(5) After the crystallization is completed, add hydrogen peroxide with a mass concentration of 25% until the system changes color, keep the water bath temperature at 6°C, and stir for 10 minutes;

(6) After aging, the mixture was washed with acetone until the system became neutral, filtered, and the solid was collected. The solid powder was dried at 80° C. and then sieved to obtain LED phosphor. The SEM image of the obtained LED phosphor is shown in FIG2 .

Comparative Example 2

The preparation method of the LED phosphor of the comparative example of the present invention is as follows:

(1) Preparation of potassium bifluoride hydrofluoric acid solution: Potassium bifluoride is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium bifluoride hydrofluoric acid solution, wherein the molar concentration of potassium bifluoride is 2 mol/L;

(2) Preparation of a potassium fluorosilicate hydrofluoric acid solution: Potassium fluorosilicate is added to hydrofluoric acid having a mass concentration of 41% to prepare a potassium fluorosilicate hydrofluoric acid solution, wherein the molar concentration of the potassium fluorosilicate is 1.5 mol/L;

(3) Measure 2.5 L of a 41% hydrofluoric acid solution, add 6 g of potassium fluoromanganate at 3° C., stir for 2-4 min until the solid is completely dissolved, then add the mixture to 200 mL of a 3° C. potassium fluorosilicate hydrofluoric acid solution, stir for 2-4 min, and obtain a mixed solution;

(4) placing the mixed solution in step (3) in an ultrasonic water bath temperature control device, the water bath temperature is controlled at 6°C, stirring and ultrasonic generator are turned on at the same time, the frequency of the ultrasonic wave is adjusted to 5kHz, after the temperature of the device is stable, potassium bifluoride hydrofluoric acid solution at a temperature of 3°C is added dropwise, the addition rate is 6.5mL/s, the drop volume is 400mL, after the addition is completed, stirring and ultrasonic crystallization are continued at this ultrasonic frequency for 10min;

(5) After the crystallization is completed, hydrogen peroxide with a mass concentration of 25% is added dropwise until the system changes color, and then acetone is used to wash until the system becomes neutral, and the solid is collected by filtration. The solid powder is dried at a temperature of 80° C. and then sieved to obtain LED phosphor.

Comparative Example 3

The only difference between the preparation process of the LED phosphor of the comparative example of the present invention and that of Example 1 is that the frequency of ultrasound is controlled to be 80 kHz.

Comparative Example 4

The only difference between the preparation process of the LED phosphor of the comparative example of the present invention and that of Example 1 is that in step (4), the water bath temperature is controlled at 18°C.

Comparative Example 5

The only difference between the preparation process of the LED phosphor of the comparative example of the present invention and that of Example 1 is that in step (2), the molar concentration of potassium fluorosilicate in the hydrofluoric acid solution of potassium fluorosilicate is 3 mol/L.

Comparative Example 6

The only difference between the preparation process of the LED phosphor of the comparative example of the present invention and that of Example 1 is that the amount of potassium fluoromanganate added is 12 g.

Effect example

The LED phosphors prepared in Examples 1-4 and Comparative Examples 1-6 were observed and recorded under a scanning electron microscope, and their particle size distribution was detected. The luminous intensity of the LED phosphors and the amount of powder used for LED lamp bead encapsulation were also tested. The structural statistics of the tests are shown in Table 4.

Powder quantity for packaging: Use 2835 450-457nm wavelength blue light chip, use LED aluminate yellow powder with a peak wavelength of 534nm, LED fluoride red phosphor and AB glue to make fluorescent glue, and use packaging equipment to package into 2700K SMD lamp beads. The ratio of LED fluoride red phosphor in fluorescent glue is the powder quantity for packaging of each embodiment of this patent, among which the powder quantity for packaging of LED fluoride red phosphor in embodiment 1 is 100%.

Relative luminous efficacy: The LED fluoride red phosphor synthesized in Example 1 is encapsulated into a 2700K SMD lamp bead, and the luminous efficacy value tested by the HASS-2000 spectrometer of the Yuanfang Optoelectronics LED light, color and electricity comprehensive test system is set to 100%, and compared with the relative luminous efficacy values of other embodiments.

Table 4: Test data of LED phosphors prepared in Examples 1-4 and Comparative Examples 1-6

It can be seen from Table 4 that the D ₅₀ of the LED phosphor prepared by the technical solution of the present invention in Examples 1-4 is 3.72-21.4 μm, and the P value is 0.86-0.98, both of which indicate that the LED phosphor prepared by the present invention has a smaller particle size and good distribution concentration; in addition, it can be seen from Table 4 that the yield of the phosphor obtained by the technical solution provided by the present invention is high, the yield is above 88.4%, and the obtained product has high relative brightness and less powder is used for packaging;

In addition, it can be seen from Examples 1 and 2 of the present invention and Comparative Example 1 that whether ultrasound is used and the frequency of ultrasound will affect the yield, particle size and distribution uniformity of the product. When ultrasound is not used, the particle size of the prepared powder increases significantly, and the distribution uniformity decreases significantly; when the frequency of ultrasound is too high, the product particle size is too small, resulting in an unstable structure, and it is very easy to be oxidized during the synthesis process, resulting in synthesis failure;

It can be seen from Example 1, Example 3 and Comparative Example 6 of the present invention that changing the amount of potassium fluoromanganate added will greatly reduce the amount of powder used in the product, and will also lead to quenching of the excitation center concentration, resulting in a serious decrease in the luminescence performance of the product;

It can be seen from Example 1 of the present invention and Comparative Example 2 that when there is no aging after the crystallization quenching reaction, the product yield will decrease significantly, and the luminescence performance of the product will be seriously reduced;

It can be seen from Example 1 of the present invention and Comparative Example 4 that when the temperature of the water bath temperature control is set too high during the crystallization process, the particle size of the product will increase significantly, the powder concentration will deteriorate significantly, and the amount of powder used in the product will also increase;

It can be seen from Example 1 of the present invention and Comparative Example 5 that when the molar concentration of potassium fluorosilicate in the hydrofluoric acid solution of potassium fluorosilicate is too high, the particle size of the product decreases, but a large amount of impurities are generated during the synthesis process, causing the luminescent properties of the product to be seriously reduced, while increasing the amount of powder used in the finished product.

Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims (5)

1. The LED fluorescent powder is characterized in that the structural formula of the LED fluorescent powder is A ₂ (MF ₆ ):Mn ⁴⁺ Of which D is ₅₀ ＝3.5-21.5μm，D ₁₀ ≥1.0μm，D ₉₀ Less than or equal to 31.65 mu m and a particle size distribution coefficient P = (D) ₉₀ -D ₁₀ )/D ₅₀ ≤1.0；

Wherein A comprises Li, na, K, rb, cs and NH ₄ M comprises any one of Ge, si, sn, ti, zr and Sc;

the preparation method of the LED fluorescent powder comprises the following steps:

(1) Adding a hydrofluoric acid solution of fluorosilicate with the temperature of 0-6 ℃ into a hydrofluoric acid solution of hexafluoromanganate with the temperature of 0-6 ℃, and stirring and mixing to obtain a mixed solution;

(2) Placing the mixed solution at 2-10 ℃ for ultrasonic stirring, and dropwise adding hydrofluoric acid solution of fluorohydrogenate at the dropwise adding speed of 2-10 mL/s;

(3) After the dropwise addition is finished, ultrasonically stirring, crystallizing, quenching, aging, washing and drying to obtain the LED fluorescent powder;

in the step (3), the ultrasonic frequency is 5-50kHz; the crystallization temperature is 2-10 ℃, and the crystallization time is 8-12min; the aging temperature is 2-10 deg.C, and the aging time is 2-8min.

2. The LED fluorescent powder as claimed in claim 1, wherein in the step (1), the mass-to-volume ratio of the hexafluoromanganate to the hydrofluoric acid solution is (6-9) g:2.5L.

3. The LED phosphor as claimed in claim 1, wherein in the step (2), the frequency of the ultrasound is 5 to 50kHz.

4. The LED phosphor as claimed in claim 1, wherein in the step (2), the molar concentration of the fluorohydrogenate in the hydrofluoric acid solution of the fluorohydrogenate is 1.8-2.2mol/L.

5. Use of the LED phosphor of claim 1 in LED products.

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