A high brightness fluorescent powder and preparation method thereof

Abstract

The present application belongs to the technical field of fluorescent material preparation, and discloses a method for preparing a high-brightness fluorescent powder. The method comprises the following steps: firstly placing hydrofluoric acid in a stirring device and stirring it, then dropping a potassium hexafluoromanganate precursor, a mixed solution one, and a mixed solution two in turn into the hydrofluoric acid in a stirring state to obtain a mixed solution three, then dropping a potassium salt solution into the mixed solution three in a stirring state to obtain a mixed solution four, then placing the hydrofluoric acid in a stirring device and stirring it, then dropping a potassium hexafluoromanganate precursor and a mixed solution five in turn into the hydrofluoric acid in a stirring state to obtain a mixed solution six, finally placing the mixed solution four in a stirring device and stirring it, then dropping the mixed solution six into the mixed solution four in a stirring state to obtain a mixed solution seven, then coating the mixed solution seven, washing, drying, and sieving to obtain a high-brightness fluorescent powder. In addition, the present application also discloses a high-brightness fluorescent powder.

Description

Technical Field

[0001] This application relates to the technical field of preparing fluorescent materials, and particularly relates to a high-brightness phosphor and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of optoelectronic technology, fluoride phosphors, as an important luminescent material, have been widely used in fields such as fluorescent displays, LED lighting, and bioimaging. However, traditional fluoride phosphors have some limitations in terms of luminous efficiency, luminous wavelength range, and light stability, which limit their application in high-performance optoelectronic devices.

[0003] Currently, research on (K 2 SiF 6 :Mn 4+ ) phosphors has made certain progress. (K 2 SiF 6 :Mn 4+ ) has excellent properties of high luminous efficiency and luminous intensity, and can produce a stable and uniform fluorescence effect. In addition, (K 2 SiF 6 :Mn 4+ ) phosphors have a broad luminous wavelength in the visible spectral range, can adjust the emission color, and provide more selection space for optoelectronic devices. In addition, (K 2 SiF 6 :Mn 4+ ) phosphors have good light stability and chemical stability, are suitable for long-term lighting and display, are not easily affected by chemical substances, and have high stability and reliability.

[0004] However, although (K 2 SiF 6 :Mn 4+ ) phosphors perform well in terms of luminous performance and stability, there are still some challenges and room for improvement. First, it is necessary to further improve the luminous efficiency of (K 2 SiF 6 :Mn 4+ ) phosphors to meet the requirements of optoelectronic devices for high brightness and high contrast. Second, it is necessary to expand the application fields of (K 2 SiF 6 :Mn 4+ ) phosphors and explore their potential application values in fields such as bioimaging, photocatalysis, and optical communication. In addition, it is also necessary to pay attention to the environmental protection performance of (K 2 SiF 6 :Mn 4+ ) phosphors and develop more environmentally friendly and sustainable preparation methods to meet the needs of green environmental protection.

[0005] In the future, the development directions of potassium fluorosilicate fluoride phosphors include but are not limited to: further optimizing the material structure and preparation process to improve the luminescence efficiency and stability; expanding the application fields to explore new application scenarios and market demands; paying attention to environmental protection and sustainability to develop more environmentally friendly preparation methods and material recycling schemes. Through continuous research and innovation, potassium fluorosilicate fluoride phosphors are expected to become important luminescent materials in future optoelectronic devices, promoting the development and application of optoelectronic technologies.

[0006] Chinese Patent Application No. 202211043571.4 discloses a preparation method of a red phosphor, and the chemical formula composition of the phosphor is: A 2 B 1-x F 6 :Mn x , where A is one or more elements of Li, Na, K, Cs, Ag, and Cu; B is one or more elements of Si, Sn, Ti, and Ge; 0.001 ≤ x ≤ 0.5; the preparation method of the phosphor includes the following steps:

[0007] S1) Prepare a fluoromanganate with an A 2 MnF 6 structure containing Mn 4+ , and the specific steps are as follows:

[0008] S1-1) Prepare hydrofluoric acid containing a fluoride or hydrogen fluoride of A for the reaction to obtain a solution for the first reaction; dissolve potassium permanganate in hydrofluoric acid to prepare a solution for the second reaction; mix hydrofluoric acid and hydrogen peroxide to prepare a solution for the third reaction;

[0009] S1-2) Cool the solution for the third reaction by freezing to -26 to -8 °C for standby;

[0010] S1-3) Place the solution for the third reaction cooled by freezing in step S1-2) into a reaction vessel with a heat preservation structure. With stirring, spray the solution for the first reaction and the solution for the second reaction into the reaction vessel. When the color of the reaction solution in the reaction vessel changes from yellow to purple, stop adding the solution for the first reaction and the solution for the second reaction, and then measure and add the solution for the third reaction cooled by freezing in step S1-2). When the color of the reaction solution in the reaction vessel changes from purple to yellow, let it stand, and then separate the golden precipitate, wash it, and dry it to obtain A 2 MnF 6 ;

[0011] S2) Preparation of a fluoride phosphor with an A 2 B 1-x F 6 :Mn x structure:

[0012] S2-1) Prepare the solution for Reaction No. 4: Take hydrofluoric acid, add fluoride or hydrogen fluoride containing element A thereto, and after dissolution, add A prepared in step S1). 2 MnF 6 , and after complete dissolution, obtain the solution for Reaction No. 4;

[0013] S2-2) Prepare the solution for Reaction No. 5: Take another hydrofluoric acid solution, heat it to a certain temperature, add a certain amount of fluorine-containing salts, acids or oxides thereto, and after complete dissolution, obtain the solution for Reaction No. 5;

[0014] S2-3) Keep the temperature of the solution for Reaction No. 5 constant, spray the solution for Reaction No. 4 into the solution for Reaction No. 5 while stirring, and perform solid-liquid separation and drying on the reaction product to obtain the phosphor;

[0015] The hydrofluoric acid used in step S1) and step S2) is an aqueous hydrofluoric acid solution with a mass concentration of greater than or equal to 40%;

[0016] The above solution improves the purity of the phosphor by reducing the temperature of the reaction system for preparing the fluoromanganate containing Mn with A 2 MnF 6 structure and reducing the impurities of A and Mn in the fluoromanganate containing Mn with A 4+ structure. However, through the analysis of the above solution, it can be seen that the above solution does not make excessive designs on the addition positions of the raw materials, the potassium source, and the ratio between the silicon source during the preparation process. 2 MnF 6 structure and reducing the impurities of A and Mn in the fluoromanganate containing Mn with A 4+ structure. However, through the analysis of the above solution, it can be seen that the above solution does not make excessive designs on the addition positions of the raw materials, the potassium source, and the ratio between the silicon source during the preparation process.

[0017] Chinese Patent Application No. 202210490258.9 discloses a phosphor composition with high luminous efficiency and a COB flexible light strip. The phosphor composition contains 40 wt% - 66 wt% of fluoride red phosphor, and the structural formula of the fluoride red phosphor is K 2 Si (1-x) F 6 :Mn x , where x = 0.045 - 0.070;

[0018] The phosphor composition containing fluoride red phosphor provided by the above solution has higher lamp-making luminous efficiency performance. In the color temperature range of 2700K - 6500K and a color rendering index of 90Ra, the lamp-making luminous efficiency is increased by at least 8% or more. However, further observing this solution, it can be seen that this solution does not make excessive descriptions and designs on the preparation method of the phosphor.

[0019] Problems to be solved by this solution: How to provide a preparation method of a phosphor to make the particle size of the phosphor more uniform and further improve the brightness and luminous flux. Summary of the Invention

[0020] One of the purposes of this application is to provide a preparation method of a high-brightness phosphor,

[0021] Another purpose of this application is to provide a high-brightness phosphor;

[0022] To achieve the above purposes, this application discloses a preparation method of a high-brightness phosphor, including the following steps:

[0023] Step 1: Place hydrofluoric acid in a stirring device and stir, and then sequentially drop the potassium hexafluoromanganate precursor, mixture one, and mixture two into the stirring hydrofluoric acid to obtain mixture three;

[0024] Step 2: Drop the potassium salt solution into the stirring mixture three to obtain mixture four;

[0025] Step 3: Place hydrofluoric acid in a stirring device and stir, and then sequentially drop the potassium hexafluoromanganate precursor and mixture five into the stirring hydrofluoric acid to obtain mixture six;

[0026] Step 4: Place mixture four in a stirring device and stir, and then drop mixture six into the stirring mixture four to obtain mixture seven. Then, envelope, wash, dry, and screen mixture seven to obtain a high-brightness phosphor;

[0027] During the preparation process, the dropping of mixture one, mixture two, the potassium salt solution, mixture five, and mixture six is realized through a nozzle. And in step 1, when adding the potassium hexafluoromanganate precursor, the adding position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0028] In step 1, when dropping mixture one, the flow rate of mixture one is 1.5 - 2.5 L / min, and the dropping position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0029] In step 1, when dropping mixture two, the flow rate of mixture two is 1.0 - 1.5 L / min, and the dropping position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0030] In step 2, when dropping the potassium salt solution, the flow rate of the potassium salt solution is 1.0 - 1.5 L / min, and the dropping position is at the edge of the vortex formed by the stirring mixture three;

[0031] In Step 3, when adding the fifth mixture, the flow rate of the fifth mixture is 1.5 - 2.5 L / min, and the adding position is at the edge of the vortex formed by the hydrofluoric acid under stirring;

[0032] In Step 3, when adding the potassium hexafluoromanganate precursor, the adding position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the hydrofluoric acid under stirring;

[0033] In Step 4, when adding the sixth mixture, the flow rate of the sixth mixture is 0.1 - 0.2 L / min, and the adding position is at the edge of the vortex formed by the fourth mixture under stirring;

[0034] The first mixture is a mixture prepared from a silicon source, hydrofluoric acid and water;

[0035] The second mixture is a mixture prepared from potassium hydrogen fluoride and hydrofluoric acid;

[0036] The fifth mixture is a mixture prepared from a silicon source, hydrofluoric acid and water;

[0037] The potassium salt in the potassium salt solution is selected from at least one of potassium chloride, potassium fluoride, potassium bromide, potassium sulfate, potassium nitrate;

[0038] The silicon source is selected from at least one of silicon dioxide and silicon monoxide.

[0039] Preferably, the potassium hexafluoromanganate precursor is prepared by dissolving potassium fluoride and potassium permanganate in hydrofluoric acid and then precipitating potassium hexafluoromanganate with hydrogen peroxide.

[0040] Preferably, in the third mixture, the concentration of potassium ions is greater than that of silicon ions;

[0041] In the sixth mixture, the concentration of silicon ions is greater than that of potassium ions;

[0042] In the seventh mixture, the concentration of potassium ions is greater than that of silicon ions.

[0043] Preferably, in Step 1, the temperature of the first mixture is 5 - 10 °C;

[0044] The temperature of the second mixture is 5 - 10 °C

[0045] The temperature of the hydrofluoric acid is 3 - 7 °C, and the temperature of the hydrofluoric acid is lower than the temperatures of the first mixture and the second mixture.

[0046] Preferably, in Step 2, the temperature of the potassium salt solution is 5 - 10 °C, and the temperature of the potassium salt solution in Step 2 is higher than the temperature of the hydrofluoric acid in Step 1.

[0047] Preferably, in Step 3, the temperature of the hydrofluoric acid is 3 - 7 °C, and the temperature of the fifth mixture is 5 - 10 °C.

[0048] Preferably, the distance between the nozzle and the liquid level of the liquid in the stirring device is 3-6 cm.

[0049] Preferably, step 4 is specifically as follows: place the mixed liquid four in the stirring device and stir it, then dropwise add the mixed liquid six to the mixed liquid four in a stirring state to obtain the mixed liquid seven, and then mix, wash, dry, and sieve the mixed liquid seven with hydrogen peroxide and silica solution to obtain a high-brightness phosphor.

[0050] In addition, the present application also discloses a phosphor, which is prepared by the above-mentioned method for preparing a high-brightness phosphor. The brightness of the phosphor is 100-120, and the median particle size of the phosphor is 25-32 μm.

[0051] Preferably, the luminous flux of the phosphor is greater than or equal to 99%.

[0052] The beneficial effects of the present application are as follows:

[0053] Since small-sized phosphors can effectively reduce internal scattering and reduce internal light absorption loss. At the same time, it is beneficial to improve the luminescence uniformity, with smaller fluctuations in color coordinates and color rendering index, and improve the packaging yield. This is because in the cured glue, the smaller the phosphor, the less likely it is to precipitate to the bottom of the chip, and the narrower the particle size distribution and the closer the particle size, the more conducive to the uniformity of precipitation. Therefore, the phosphor after baking will be more uniform; and in the present application, the particle size is regulated by changing the feeding position, so that the particle size of the phosphor is more controllable and the particle size is more uniform, thereby reducing the light absorption loss and improving the luminescence uniformity. Specific embodiments

[0054] The following will clearly and completely describe the present application in combination with the embodiments of the present application. In the description of the present application, it should be noted that for those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0055] Example 1

[0056] S1: Preparation of potassium hexafluoromanganate precursor

[0057] S1-1) Add 32 L of hydrofluoric acid to the bucket and turn on the stirrer;

[0058] S1-2) Measure 7 kg of potassium fluoride and slowly add it to the bottom liquid;

[0059] S1-3) After waiting for the circulating water to cool the solution to 30 °C, add 480 g of potassium permanganate and stir for 1 hour;

[0060] S1-4) Add 480 ml of hydrogen peroxide, with a titration time of 2 h. The solution changes from purple to brownish - black, and then continue to stir for 10 min;

[0061] S1-5) Wait for the precursor to precipitate, extract the upper layer solution, rinse the precursor with alcohol, perform wet sieving on the precursor containing alcohol, then carry out suction filtration until dry, place it on a tray and dry at a temperature of 70 °C. After drying for 12 h, perform dry sieving to obtain the potassium hexafluoromanganate precursor.

[0062] S2: Preparation of high - brightness phosphor

[0063] Step 1: Place 11 L of hydrofluoric acid at a temperature of 7 °C in a stirring device and stir. Subsequently, add 14 g of the potassium hexafluoromanganate precursor, 0.45 L of mixture one at a temperature of 10 °C, and 0.3 L of mixture two at a temperature of 10 °C to the stirring hydrofluoric acid in sequence to obtain mixture three;

[0064] Step 2: Add 2.5 L of potassium chloride solution at a temperature of 10 °C to the stirring mixture three to obtain mixture four;

[0065] Step 3: Place 1 L of hydrofluoric acid at a temperature of 3 °C in a stirring device and stir. Subsequently, add 12 g of the potassium hexafluoromanganate precursor and 0.45 L of mixture five at a temperature of 5 °C to the stirring hydrofluoric acid in sequence to obtain mixture six;

[0066] Step 4: Place mixture four in a stirring device and stir. Subsequently, add mixture six to the stirring mixture four to obtain mixture seven. Then, perform coating, cleaning, drying, and sieving on mixture seven to obtain high - brightness phosphor;

[0067] During the preparation process, the addition of mixture one, mixture two, potassium salt solution, mixture five, and mixture six is achieved through a nozzle. And in step 1, when adding the potassium hexafluoromanganate precursor, the addition position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0068] In step 1, when adding mixture one, the flow rate of mixture one is 1.5 L / min, and the addition position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0069] In step 1, when adding mixture two, the flow rate of mixture two is 1.0 L / min, and the addition position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0070] In step 2, when adding the potassium chloride solution, the flow rate of the potassium chloride solution is 1.0 L / min, and the addition position is at the edge of the vortex formed by the stirring mixture three;

[0071] In Step 3, when adding the fifth mixed solution, the flow rate of the fifth mixed solution is 1.5 L / min, and the dropping position is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0072] In Step 3, when adding the potassium hexafluoromanganate precursor, the adding position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0073] In Step 4, when adding the sixth mixed solution, the flow rate of the sixth mixed solution is 0.1 L / min, and the dropping position is at the edge of the vortex formed by the fourth mixed solution under stirring.

[0074] The first mixed solution is a mixed solution prepared from silicon dioxide, hydrofluoric acid and water.

[0075] The second mixed solution is a mixed solution prepared from potassium bifluoride and hydrofluoric acid.

[0076] The fifth mixed solution is a mixed solution prepared from silicon dioxide, hydrofluoric acid and water.

[0077] In the first mixed solution, the concentration of silicon dioxide is 1.5 mol / L.

[0078] In the second mixed solution, the concentration of potassium bifluoride is 6.5 mol / L.

[0079] In the potassium chloride solution, the concentration of potassium chloride is 1.2 mol / L.

[0080] In the fifth mixed solution, the concentration of silicon dioxide is 2.0 mol / L.

[0081] The distance between the nozzle and the liquid level of the liquid in the stirring device is 3 cm.

[0082] Example 2

[0083] It is basically the same as Example 1, except that:

[0084] S2: Preparation of high-brightness phosphor

[0085] Step 1: Place 12 L of hydrofluoric acid at 3°C in a stirring device and stir it. Then, sequentially add 14 g of potassium hexafluoromanganate precursor, 0.50 L of the first mixed solution at 5°C, and 0.25 L of the second mixed solution at 5°C into the stirring hydrofluoric acid to obtain the third mixed solution.

[0086] Step 2: Add 2.6 L of potassium salt solution at 5°C to the third mixed solution under stirring to obtain the fourth mixed solution.

[0087] Step 3: Place 1 L of hydrofluoric acid at 7 °C in a stirring device and stir it. Subsequently, sequentially add 12 g of the potassium hexafluoromanganate precursor and 0.50 L of mixture five at 10 °C dropwise into the stirring hydrofluoric acid to obtain mixture six;

[0088] Step 4: Place mixture four in a stirring device and stir it. Subsequently, add mixture six dropwise to the stirring mixture four to obtain mixture seven. Then, coat, wash, dry, and screen mixture seven to obtain a high-brightness phosphor;

[0089] During the preparation process, the addition of mixture one, mixture two, the potassium salt solution, mixture five, and mixture six is achieved through a nozzle. And in step 1, when adding the potassium hexafluoromanganate precursor, the addition position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0090] In step 1, when adding mixture one, the flow rate of mixture one is 2.5 L / min, and the addition position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0091] In step 1, when adding mixture two, the flow rate of mixture two is 1.5 L / min, and the addition position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0092] In step 2, when adding the potassium chloride solution, the flow rate of the potassium chloride solution is 1.5 L / min, and the addition position is at the edge of the vortex formed by the stirring mixture three;

[0093] In step 3, when adding mixture five, the flow rate of mixture five is 2.5 L / min, and the addition position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0094] In step 4, when adding mixture six, the flow rate of mixture four is 0.2 L / min, and the addition position is at the edge of the vortex formed by the stirring mixture four;

[0095] The mixture one is a mixture prepared from silicon dioxide, hydrofluoric acid, and water;

[0096] The mixture two is a mixture prepared from potassium bifluoride and hydrofluoric acid;

[0097] The mixture five is a mixture prepared from silicon dioxide, hydrofluoric acid, and water;

[0098] In mixture one, the concentration of silicon dioxide is 2.0 mol / L;

[0099] In mixture two, the concentration of potassium bifluoride is 7.5 mol / L;

[0100] The potassium salt solution is a potassium chloride solution, and in the potassium chloride solution, the concentration of potassium chloride is 0.8 mol / L;

[0101] The concentration of silicon dioxide in the fifth mixture is 1.5 mol / L;

[0102] The distance between the nozzle and the liquid level of the liquid in the stirring device is 6 cm.

[0103] Example 3

[0104] Basically the same as Example 1, the differences are as follows:

[0105] S2: Preparation of high-brightness phosphor

[0106] Step 1: Place 10 L of hydrofluoric acid at a temperature of 5°C in a stirring device and stir, then sequentially add 14 g of potassium hexafluoromanganate precursor, 0.4 L of the first mixture at a temperature of 7°C, and 0.4 L of the second mixture at a temperature of 7°C dropwise into the stirring hydrofluoric acid to obtain the third mixture;

[0107] Step 2: Add 2 L of potassium chloride solution at a temperature of 7°C dropwise to the stirring third mixture to obtain the fourth mixture;

[0108] Step 3: Place 1 L of hydrofluoric acid at a temperature of 5°C in a stirring device and stir, then sequentially add 12 g of potassium hexafluoromanganate precursor and 0.40 L of the fifth mixture at a temperature of 7°C dropwise into the stirring hydrofluoric acid to obtain the sixth mixture;

[0109] Step 4: Place the fourth mixture in a stirring device and stir, then add the sixth mixture dropwise to the stirring fourth mixture to obtain the seventh mixture, and then coat, wash, dry, and screen the seventh mixture to obtain a high-brightness phosphor;

[0110] During the preparation process, the dropping of the first mixture, the second mixture, the potassium salt solution, the fifth mixture, and the sixth mixture is realized through a nozzle. And in Step 1, when adding the potassium hexafluoromanganate precursor, the adding position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0111] In Step 1, when dropping the first mixture, the flow rate of the first mixture is 2.0 L / min, and the dropping position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0112] In Step 1, when dropping the second mixture, the flow rate of the second mixture is 1.3 L / min, and the dropping position is at the edge of the vortex formed by the stirring hydrofluoric acid;

[0113] In Step 2, when adding the potassium chloride solution, the flow rate of the potassium chloride solution is 1.3 L / min, and the dropping position is at the edge of the vortex formed by the stirred mixture three.

[0114] In Step 3, when adding the mixture five, the flow rate of the mixture five is 2.0 L / min, and the dropping position is at the edge of the vortex formed by the stirred hydrofluoric acid.

[0115] In Step 3, when adding the potassium hexafluoromanganate precursor, the adding position of the potassium hexafluoromanganate precursor is at the edge of the vortex formed by the stirred hydrofluoric acid.

[0116] In Step 4, when adding the mixture six, the flow rate of the mixture six is 0.15 L / min, and the dropping position is at the edge of the vortex formed by the stirred mixture four.

[0117] The mixture one is a mixture prepared from silicon dioxide, hydrofluoric acid and water.

[0118] The mixture two is a mixture prepared from potassium bifluoride and hydrofluoric acid.

[0119] The mixture five is a mixture prepared from silicon dioxide, hydrofluoric acid and water.

[0120] In the mixture one, the concentration of silicon dioxide is 1.8 mol / L.

[0121] In the mixture two, the concentration of potassium bifluoride is 7.2 mol / L.

[0122] In the potassium chloride solution, the concentration of potassium chloride is 1 mol / L.

[0123] In the mixture five, the concentration of silicon dioxide is 1.8 mol / L.

[0124] The distance between the nozzle and the liquid level of the liquid in the stirring device is 4 cm.

[0125] Example 4

[0126] It is basically the same as Example 1, except that in Step 1, the temperature of the hydrofluoric acid is 10 °C, the temperature of the mixture one is 7 °C, and the temperature of the mixture two is 7 °C.

[0127] Example 5

[0128] It is basically the same as Example 1, except that in Step 2, the temperature of the potassium salt solution is 5 °C.

[0129] Example 6

[0130] It is basically the same as Example 1, except that in the mixture three, the concentration of silicon ions is greater than that of potassium ions.

[0131] Example 7

[0132] It is basically the same as Example 1, except that in the third mixed solution, the concentration of silicon ions is equal to the concentration of potassium ions.

[0133] Example 8

[0134] It is basically the same as Example 1, except that in the sixth mixed solution, the concentration of silicon ions is greater than the concentration of potassium ions.

[0135] Example 9

[0136] It is basically the same as Example 1, except that in the sixth mixed solution, the concentration of silicon ions is equal to the concentration of potassium ions.

[0137] Example 10

[0138] It is basically the same as Example 1, except that in the seventh mixed solution, the concentration of silicon ions is greater than the concentration of potassium ions.

[0139] Example 11

[0140] It is basically the same as Example 1, except that in the seventh mixed solution, the concentration of silicon ions is equal to the concentration of potassium ions.

[0141] Comparative Example 1

[0142] It is basically the same as Example 1, except that in Step 1, when adding the first mixed solution, the flow rate of the first mixed solution is 1.0 L / min, and the addition position is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0143] Comparative Example 2

[0144] It is basically the same as Example 1, except that in Step 1, when adding the first mixed solution, the flow rate of the first mixed solution is 3.0 L / min, and the addition position is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0145] Comparative Example 3

[0146] It is basically the same as Example 1, except that in Step 1, when adding the second mixed solution, the flow rate of the second mixed solution is 0.5 L / min, and the addition position is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0147] Comparative Example 4

[0148] It is basically the same as Example 1, except that in Step 1, when adding the second mixed solution, the flow rate of the second mixed solution is 2.0 L / min, and the addition position is at the edge of the vortex formed by the hydrofluoric acid under stirring.

[0149] Comparative Example 5

[0150] It is basically the same as Example 1, except that in Step 2, when adding the potassium salt solution, the flow rate of the potassium salt solution is 0.5 L / min, and the addition position is at the edge of the vortex formed by the stirred mixture three.

[0151] Comparative Example 6

[0152] It is basically the same as Example 1, except that in Step 2, when adding the potassium salt solution, the flow rate of the potassium salt solution is 2.0 L / min, and the addition position is at the edge of the vortex formed by the stirred mixture three.

[0153] Comparative Example 7

[0154] In Step 3, when adding mixture five, the flow rate of mixture five is 1.0 L / min, and the addition position is at the edge of the vortex formed by the stirred hydrofluoric acid.

[0155] Comparative Example 8

[0156] In Step 3, when adding mixture five, the flow rate of mixture five is 3.0 L / min, and the addition position is at the edge of the vortex formed by the stirred hydrofluoric acid.

[0157] Comparative Example 9

[0158] It is basically the same as Example 1, except that in Step 4, when adding mixture six, the flow rate of mixture six is 0.05 L / min, and the addition position is at the edge of the vortex formed by the stirred mixture four.

[0159] Comparative Example 10

[0160] It is basically the same as Example 1, except that in Step 4, when adding mixture six, the flow rate of mixture six is 0.5 L / min, and the addition position is at the edge of the vortex formed by the stirred mixture four.

[0161] Comparative Example 11

[0162] It is basically the same as Example 1, except that in Step 1, when adding the potassium hexafluoromanganate precursor, the addition position is at the center of the vortex formed by the stirred hydrofluoric acid.

[0163] Comparative Example 12

[0164] It is basically the same as Example 1, except that in Step 1, when adding mixture one, the addition position is at the center of the vortex formed by the stirred hydrofluoric acid.

[0165] Comparative Example 13

[0166] Basically the same as Example 1, except that in Step 1, when adding the second mixture dropwise, the dropping position is at the center of the vortex formed by the hydrofluoric acid under stirring.

[0167] Comparative Example 14

[0168] Basically the same as Example 1, except that in Step 2, when adding the potassium salt solution dropwise, the dropping position is at the center of the vortex formed by the third mixture under stirring.

[0169] Comparative Example 15

[0170] Basically the same as Example 1, except that in Step 3, when adding the fifth mixture dropwise, the dropping position is at the center of the vortex formed by the hydrofluoric acid under stirring.

[0171] Comparative Example 16

[0172] Basically the same as Example 1, except that in Step 3, when adding the potassium hexafluoromanganate precursor, the adding position is at the center of the vortex formed by the hydrofluoric acid under stirring.

[0173] Comparative Example 17

[0174] Basically the same as Example 1, except that in Step 4, when adding the sixth mixture dropwise, the adding position is at the center of the vortex formed by the fourth mixture under stirring.

[0175] Comparative Example 18

[0176] Basically the same as Example 1, except that: the operations of Steps 2 and 3 are not carried out, that is:

[0177] Step 1: Place the hydrofluoric acid in a stirring device and stir, then sequentially add the potassium hexafluoromanganate precursor, the first mixture, and the second mixture dropwise into the stirring hydrofluoric acid to obtain the third mixture;

[0178] Step 4: Place the third mixture in a stirring device and stir, then dry and sieve the third mixture to obtain a high-brightness phosphor.

[0179] Comparative Example 19

[0180] Basically the same as Example 1, except that: the operation of Step 2 is not carried out, that is:

[0181] Step 1: Place the hydrofluoric acid in a stirring device and stir, then sequentially add the potassium hexafluoromanganate precursor, the first mixture, and the second mixture dropwise into the stirring hydrofluoric acid to obtain the third mixture;

[0182] Step 3: Place hydrofluoric acid in a stirring device and stir it. Subsequently, drop the potassium hexafluoromanganate precursor and mixture five into the stirring hydrofluoric acid in sequence to obtain mixture six.

[0183] Step 4: Drop mixture six into mixture three which is in a stirring state in a stirring device and stir it. Subsequently, dry and screen mixture three to obtain high-brightness phosphor powder.

[0184] Performance test

[0185] Brightness: HAAS-2000 high-precision fast optical performance test radiometer

[0186] Luminous flux: HAAS-2000 high-precision fast optical performance test radiometer (LED lamp test system)

[0187] Powder consumption: HAAS-2000 high-precision fast optical performance test radiometer (LED lamp test system)

[0188] Particle size uniformity: Laser particle size analyzer (LS-POP6 / LS-POP9)

[0189] The test results are shown in Table 1:

[0190] Table 1

[0191]

[0192]

[0193] Result analysis:

[0194] 1. It can be seen from Examples 1-5 that when making small adjustments to the flow rate, temperature, and solution volume of mixture one, mixture two, potassium chloride solution, mixture five, and mixture four in each step, there are no obvious changes in the brightness, luminous flux, particle size uniformity, etc. of the phosphor powder.

[0195] 2. As can be seen from Examples 6 - 11, when the concentration of silicon ions in Mixed Solution III is greater than or equal to the concentration of potassium ions, the concentration of silicon ions in Mixed Solution VI is greater than or equal to the concentration of potassium ions, and the concentration of silicon ions in Mixed Solution VII is greater than or equal to the concentration of potassium ions, there is an obvious downward trend in the brightness, luminous flux, and particle size uniformity of the phosphor, and an upward trend in the powder usage. We believe that the reason for this phenomenon may be: when the input amount of potassium ions in the system is relatively small, except for reacting with silicon ions, the remaining potassium ions will react less with fluoride ions, resulting in a smaller temperature rise in the solution reaction, which is not conducive to particle growth and manganese ion doping. The particle size is smaller, the ability to absorb and radiate light is weaker, and the light scattering effect is stronger, which will lead to a weaker excitation efficiency of the powder, smaller brightness. At the same time, when the manganese content is low, with the same powder usage, less light is excited, and the luminous flux is also smaller. Under the condition of the same luminous flux, more phosphor is needed to emit light to achieve the same effect, so the powder usage will also be greater;

[0196] 3. As can be seen from Example 1 and Comparative Examples 1 - 10, when the flow rates of Mixed Solution I, Mixed Solution II, potassium chloride solution, Mixed Solution V, and Mixture VI in each step are adjusted significantly, there is an obvious downward trend in the brightness, luminous flux, and particle size uniformity of the phosphor. We believe that, on the one hand, when the flow rates of Mixed Solution I, Mixed Solution II, potassium chloride solution, Mixed Solution V, and Mixture IV are too small, the concentration of the reaction per unit time becomes dilute. At low concentrations, the crystals tend to grow. During the growth process, due to the temperature difference between the reaction position and other positions in the solution, there will be small particles and large particles in the overall solution environment. The more intense the growth process, the greater the difference in particles. Therefore, along with the growth process, the particle uniformity becomes worse. At the same time, in the low - concentration reaction, the reaction is relatively slow, and the promotion effect on the doping effect of manganese ions is not significant, so it will lead to a slightly lower brightness of the powder and the luminous flux after encapsulation;

[0197] When the flow rates of Mixed Solution I, Mixed Solution II, potassium chloride solution, Mixed Solution V, and Mixture VI are too large, it will lead to an increase in the local reaction concentration, thus promoting the fluoride synthesis reaction. The nucleation process of small - sized crystals accounts for a large part, and the growth process accounts for a small part, ultimately affecting the crystal morphology. Generally, the smoother the crystal morphology, the weaker the light scattering and other effects, and the more conducive it is to light output. However, since the growth process of small - sized crystals accounts for a small proportion, this will increase the surface area of the powder, and the surface is not smooth, which will reduce the light output efficiency, the brightness of the powder, and the luminous flux after encapsulation;

[0198] 4. As can be seen from Example 1 and Comparative Examples 11 - 17, when the addition positions of Mixture 1, Mixture 2, potassium chloride solution, Mixture 5, and potassium hexafluoromanganate are at the center of the vortex formed by the solution, there is an obvious downward trend in the luminous flux and particle size uniformity of the phosphor, and an obvious upward trend in brightness and phosphor consumption. We believe that because the dispersion ability in the central region of the vortex-shaped liquid is stronger, the above-mentioned Mixture 1, Mixture 2, potassium chloride solution, Mixture 5, and potassium hexafluoromanganate are too highly dispersed in the system, the reaction concentration per unit area is lower, resulting in too large particle sizes. At the same time, since the concentration and temperature at the titration position in the solution are inconsistent with those at other positions, the driving force for the crystal growth process in the reaction system is different, and the difference in particles during the growth process will become larger and larger, resulting in a decrease in the particle size uniformity; because large-sized phosphors themselves have characteristics such as strong absorption of radiation and weak scattering, and at the same time the reaction concentration is low, the doping efficiency of manganese will also be lower, resulting in a decline in the overall performance of the phosphor, and further causing an increase in the luminous flux and phosphor consumption after encapsulation, and an increase in the phosphor cost.

[0199] 5. As can be seen from Example 1 and Comparative Examples 18 - 19, when the potassium and silicon supplementation operations in Steps 2 and 3 are not carried out, there is an obvious downward trend in the brightness, luminous flux, and particle size uniformity of the phosphor. We believe that the reason for this phenomenon is that when the silicon source and low-concentration potassium source in Steps 2 and 3 are lacking, the crystal synthesis mainly focuses on nucleation, resulting in the crystal lacking the primary and secondary growth processes, making the crystal particle size smaller and the surface roughness increase, thereby reducing the luminous efficiency of the phosphor and the luminous flux after encapsulation;

[0200] When the potassium supplementation operation in Step 2 is not carried out, there is an obvious downward trend in the brightness, luminous flux, and particle size uniformity of the phosphor. We believe that the reason for this phenomenon is that in the hydrofluoric acid bottom solution, only Mixture 1, high-concentration Mixture 2, and Mixture 5 react, which will facilitate the nucleation process of the crystal, the particle size will be smaller, and the light scattering ability will be stronger, further reducing the brightness of the powder; at the same time, the surface of the crystal after nucleation is not as smooth as that of the crystal after growth, and the shape is irregular, which will also reduce the luminous flux after encapsulation. In addition, if the operation of supplementing the low-concentration potassium source is not carried out, the potassium content in the solution will decrease, which will reduce the reaction between potassium ions and fluoride ions in the solution, the reaction temperature rise will decrease, the particle size and the doping amount of manganese will decrease accordingly, and finally the brightness and luminous flux will decrease.

[0201] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing a high-brightness phosphor, characterized in that: The following steps are involved: Step 1: placing hydrofluoric acid in a stirring device and stirring it, and then dropping a potassium hexafluoromanganate precursor, a mixed solution 1, and a mixed solution 2 into the stirred hydrofluoric acid in sequence to obtain a mixed solution 3; Step 2: adding the potassium salt solution dropwise to the mixed solution 3 in a stirring state to obtain a mixed solution 4; Step 3: placing hydrofluoric acid in a stirring device and stirring, and then dropping the potassium hexafluoromanganate precursor and the mixed solution 5 into the stirred hydrofluoric acid in sequence to obtain the mixed solution 6; Step 4: placing the mixed solution 4 in a stirring device and stirring it, then dropping the mixed solution 6 into the stirred mixed solution 4 to obtain the mixed solution 7, then coating the mixed solution 7, washing, drying, and sieving to obtain a high-brightness phosphor; In the preparation process, the mixed solution 1, the mixed solution 2, the potassium salt solution, the mixed solution 5, and the mixed solution 6 are added dropwise through the nozzle, and in step 1, when the potassium hexafluoromanganate precursor is added, the adding position of the potassium hexafluoromanganate precursor is the edge of the vortex formed by the hydrofluoric acid in the stirring state; In step 1, when the mixed solution 1 is added dropwise, the flow rate of the mixed solution 1 is 1.5 to 2.5 L / min, and the dropping position is the edge of the vortex formed by the hydrofluoric acid in a stirring state; In step 1, when the mixed solution 2 is added dropwise, the flow rate of the mixed solution 2 is 1.0 to 1.5 L / min, and the dropping position is the edge of the vortex formed by the hydrofluoric acid in a stirring state; In step 2, when the potassium salt solution is added dropwise, the flow rate of the potassium salt solution is 1.0 to 1.5 L / min, and the dropping position is the edge of the vortex formed by the mixed solution 3 in a stirring state; In step 3, when the mixed solution 5 is added dropwise, the flow rate of the mixed solution 5 is 1.5 to 2.5 L / min, and the dropping position is the edge of the vortex formed by the hydrofluoric acid in a stirring state; In step 3, when the potassium hexafluoromanganate precursor is added, the potassium hexafluoromanganate precursor is added at the edge of the vortex formed by the hydrofluoric acid in a stirring state; In step 4, when the mixed solution 6 is added dropwise, the flow rate of the mixed solution 6 is 0.1-0.2 L / min, and the dropping position is the edge of the vortex formed by the mixed solution 4 in a stirring state; The first mixed solution is a mixed solution made of silicon source, hydrofluoric acid and water; The second mixed solution is a mixed solution made of potassium bifluoride and hydrofluoric acid; The mixed solution five is a mixed solution made of silicon source, hydrofluoric acid and water; The potassium salt in the potassium salt solution is selected from at least one of potassium chloride, potassium fluoride, potassium bromide, potassium sulfate and potassium nitrate; The silicon source is selected from at least one of silicon dioxide and silicon monoxide.

2. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: The potassium hexafluoromanganate precursor is prepared by dissolving potassium fluoride and potassium permanganate in hydrofluoric acid and then precipitating the potassium hexafluoromanganate by hydrogen peroxide.

3. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: In mixed solution three, the concentration of potassium ions is greater than the concentration of silicon ions; In mixed solution 6, the concentration of silicon ions is greater than that of potassium ions; In mixed solution seven, the concentration of potassium ions is greater than the concentration of silicon ions.

4. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: In step 1, the temperature of the mixed solution 1 is 5-10°C; The temperature of the mixed solution 2 is 5-10°C The temperature of the hydrofluoric acid is 3-7° C., and the temperature of the hydrofluoric acid is lower than the temperature of the first mixed solution and the second mixed solution.

5. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: In step 2, the temperature of the potassium salt solution is 5-10° C., and the temperature of the potassium salt solution in step 2 is higher than the temperature of the hydrofluoric acid in step 1.

6. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: In step 3, the temperature of the hydrofluoric acid is 3-7°C, and the temperature of the mixed solution 5 is 5-10°C.

7. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: The distance between the nozzle and the liquid surface of the liquid in the stirring device is 3 to 6 cm.

8. The method for preparing a high-brightness phosphor according to claim 1, characterized in that: The step 4 is specifically as follows: placing the mixed solution 4 in a stirring device and stirring it, then dropping the mixed solution 6 into the stirred mixed solution 4 to obtain the mixed solution 7, then mixing the mixed solution 7 with hydrogen peroxide and silicon dioxide solution, washing, drying, and sieving to obtain a high-brightness phosphor.

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