Degradation-preventing red phosphor, method for manufacturing the same, and use

Abstract

The present application relates to a degradation-resistant red phosphor, its manufacturing method, and its use, which belong to the technical field of phosphor materials. The degradation-resistant red phosphor of the present application has a core-shell structure, the core-shell structure including a core and a shell, the core and the shell being independently selected from materials represented by Chemical Formula I: A2M (1-x) F6:xMn 4+ The present application is 4+ The atomic percentage of Mn is controlled to be lowest in the innermost layer of the core and highest in the outermost layer of the core. 4+ The content of the phosphor is extremely low, and thus the phosphor core is covered with a shell, which improves the moisture resistance and deterioration prevention ability of the phosphor, and at the same time, in combination with the core, is advantageous in maintaining a relatively high luminous efficiency.

Description

[Technical Field]

[0001] This application relates to a degradation-preventing red phosphor, a method for manufacturing the same, and its use, and belongs to the technical field of phosphor materials. [Background technology]

[0002] In LED lighting, the phosphor is typically dispersed with silica gel through stirring, and then spotted into the LED packaging bracket cup with spinning bond. During use, excitation light is emitted from the blue chip, absorbed by the phosphor within the LED package, and then the phosphor's light is propagated by reflection, refraction, and other processes. When the excitation light is shone on the surface of the phosphor, scattering occurs, and some of the phosphor's light efficiency is lost.

[0003] A red phosphor with high luminescence efficiency should satisfy the following conditions: 1) strong absorption at approximately 450 nm, 2) narrow emission at approximately 630 nm, and 3) low emission above 650 nm. K2SiF6:Mn 4+ Fluorescent materials have emission spectra that match these characteristics, have a color rendering index (CRI) greater than 90, and offer significant advantages over conventional red nitride phosphors in terms of luminescence efficiency. However, MnF6 2- Due to surface hydrolysis of the substrate, the fluoride phosphor has low moisture resistance, which can easily degrade the performance of the corresponding LED package device during long-term use.

[0004] Conventional technology involves using a reducing agent to treat the surface of phosphor particles with Mn 4+ After the activation center deactivation treatment is applied, the closer the phosphor particles are to the shell from the inside out after the treatment, the more Mn 4+ This invention provides a tetravalent Mn-doped fluoride phosphor that forms a core-shell structure with a low content of [unclear]. This method improves the moisture resistance of the phosphor to some extent, but adversely affects the luminescence efficiency of the phosphor. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Regarding the deficiencies of the prior art, the present application provides a deterioration-preventing red phosphor, a method for manufacturing the same, and its use. By adopting a core-shell structure, controlling the concentration of the activator to be the lowest in the innermost layer of the core and the highest in the outermost layer of the core, with an extremely low content of the activator, and providing a shell that does not contain an activator to coat the phosphor core, it is beneficial to improve the moisture resistance and deterioration prevention ability of the phosphor, and at the same time, maintain a relatively high luminous efficiency in combination with the core.

Means for Solving the Problems

[0006] The first object of the present application is to provide a deterioration-preventing red phosphor, and the technical solution adopted is as follows. A deterioration-preventing red phosphor having a core-shell structure, the core-shell structure including a core and a shell, the core and the shell being independently selected from substances represented by Chemical Formula I: A2M (1-x) F6:xMn 4+ In Chemical Formula I, A includes at least one of Li, Na, K, Rb, and Cs, and M includes at least one of Si, Ge, and Ti. Here, the atomic percentage of Mn in the innermost layer of the core 4+ is a, the atomic percentage of Mn in the outermost layer of the core 4+ is b, b > a, the atomic percentage of Mn at each location inside the core particles of the phosphor 4+ is x1, the value range of x is a ≤ x1 ≤ b, the atomic percentage of Mn in the shell 4+ is x2, the value range of x2 is 0 ≤ x2 ≤ 0.1%. In the present application, the phosphor is in particle form. The innermost layer of the core refers to the central layer inside the phosphor particles, and at the same time, it is also the layer with the lowest atomic percentage of Mn. The outermost layer of the core refers to the layer with the highest atomic percentage of Mn in the phosphor. The shell refers to the part of the phosphor other than the outermost layer of the core, that is, the part from the outermost layer of the core, excluding the outermost layer of the core, to the outer surface of the phosphor. The present application is about Mn 4+ and the atomic percentage of Mn in the outermost layer of the core 4+ is the highest layer, and the shell refers to the part of the phosphor other than the outermost layer of the core, that is, the part from the outermost layer of the core, excluding the outermost layer of the core, to the outer surface of the phosphor. The present application is about Mn 4+By controlling the atomic percentage of Mn to be lowest in the innermost layer of the core and highest in the outermost layer, it is advantageous to reduce the activator concentration at the core center of the phosphor, suppress the thermal quenching effect, and improve thermal stability. Furthermore, it is advantageous to increase the concentration of activator ions on the core surface, thereby improving the absorption rate of the phosphor to excitation light, further suppressing the scattering effect, and improving the luminous efficiency of the corresponding LED device. 4+ By covering the phosphor core with a shell containing an extremely low amount of [unclear], contact between the luminescent center and the external environment is avoided, improving the phosphor's moisture resistance and degradation prevention capabilities. Furthermore, this does not affect the phosphor's luminescence efficiency in conjunction with the core, which is advantageous for the phosphor to stably maintain high luminescence intensity during long-term use.

[0007] Furthermore, in the aforementioned shell, the range of the value of x2 is 0 ≤ x2 ≤ 0.05%, which further improves the moisture resistance and degradation prevention ability of the phosphor particles.

[0008] Preferably, x1 tends to increase from the inside to the outside in the radial direction of the core. In this application, x1 tending to increase from the inside to the outside in the radial direction means that the Mn inside the phosphor particles 4+ The content of Mn shows an overall increasing trend from the inside to the outside in the radial direction, that is, with the distance from the innermost layer in the radial direction as the horizontal axis, 4+ The correlation curve plotted with the content of Mn on the vertical axis shows an increasing trend. However, in the radial direction of the phosphor particles, in two adjacent layers from the inside out, Mn 4+ The atomic percentage of Mn can increase, decrease, or remain constant. 4+ By controlling the atomic percentage of Mn to increase from the inside to the outside in the radial direction of the core, the innermost and outermost layers of the phosphor core are made Mn 4+ The content relationship is ensured, and at the same time, Mn in each case inside the core 4+ The smooth transition of the content from the inside to the outside in the radial direction ensures the absorption efficiency of the core to excitation light and is advantageous in promoting an improvement in the luminescence efficiency of the phosphor particles.

[0009] Preferably, the increasing trend is such that x1 increases linearly and uniformly from the inside to the outside in the radial direction of the core. In this application, linear and uniform increase means that Mn increases from the inside to the outside in the radial direction of the core. 4+ The atomic percentage of the core Mn 4+ The atomic percentage of Mn is increased linearly and uniformly, and as the phosphor particles get closer to the outermost layer of the core, 4+ The concentration of Mn is high. 4+ By controlling the content of such a substance to tend to increase uniformly in the core, the phosphor can absorb excitation light sufficiently, and it is advantageous to improve the conversion efficiency of the phosphor and further improve the luminescence efficiency of the phosphor.

[0010] Preferably, in the core, the range of the value of a is 0 ≤ a ≤ 0.1%, and the range of the value of b is 0.3% ≤ b ≤ 5%. This application relates to Mn in the core. 4+ By controlling the atomic percentage range, the Mn within the core from the innermost layer to the outermost layer can be controlled. 4+ This is advantageous for adjusting the content distribution, ensuring the concentration of activators on the core surface and inside, and improving the absorption efficiency of the phosphor.

[0011] Preferably, in the core, 0.2% ≤ (ba) ≤ 5%, and more preferably 0.5% ≤ (ba) ≤ 2%.

[0012] For example, the range of values ​​for a is 0 ≤ a ≤ 0.01%, and the range of values ​​for b is 0.5% ≤ b ≤ 1.5%.

[0013] Preferably, in the core, the value of a is 0, and the range of the value of b is 0.7% ≤ b ≤ 1%. For example, in the core, the value of a is 0, and the range of the value of b is 0.7% ≤ b ≤ 0.85%.

[0014] Preferably, in the phosphor, b > x².

[0015] Preferably, in the phosphor, 0 ≤ x² / b ≤ 1 / 10.

[0016] Preferably, the average particle size of the degradation-preventing red phosphor is 5 to 40 μm. For example, the average particle size of the degradation-preventing red phosphor is 25 to 40 μm.

[0017] Preferably, the average thickness of the shell is 0.1 to 2 μm. Using a shell with this average thickness is advantageous in improving the moisture resistance and degradation prevention ability of the phosphor, as well as in avoiding scattering of excitation light and promoting the full luminescence efficiency of the core.

[0018] The second object of this application is to provide a method for producing a degradation-preventing red phosphor, and the technical solution employed is as follows. A method for producing any of the above-mentioned degradation-preventing red phosphors, comprising: Step 1) dissolving A salt in a hydrofluoric acid solution and referring to it as base solution A; Step 2) dissolving each of the K2MnF6 series in equal masses of H2MF6 solution to prepare a series of BX solutions with different concentrations of K2MnF6; and sequentially adding the BX solution series to the base solution A, controlling the K2MnF6 concentration so that the first BX solution added has the lowest concentration of K2MnF6 and the last BX solution added has the highest concentration of K2MnF6. Step 3) includes obtaining a core mixture and using it to manufacture the core, and adding H2MF6 solution to the core mixture and using it to manufacture the shell, i.e., obtaining the degradation-preventing red phosphor, wherein the A salt is at least one selected from fluoride, hydrofluoric acid, sulfate, nitrate, bisulfate, carbonate, and bicarbonate of A, A is selected from Li, Na, K, Rb, and Cs, and in H2MF6, M is selected from Si, Ge, and Ti. The present invention uses K2MnF6 and H2MF6 solutions to prepare a BX solution series in which the concentration of K2MnF6 increases, and when mixed with base solution A, it reacts instantaneously to form A2MF6:Mn 4+ By producing a precipitate and controlling the concentration of K2MnF6 in the BX solution added first and last, Mn 4+The atomic percentage is lowest in the innermost layer of the core and highest in the outermost layer, which is advantageous in improving the overall thermal stability and luminous efficiency of the phosphor. Subsequently, H2MF6 is used and reacted with base solution A to produce a shell, improving the moisture resistance and degradation prevention ability of the phosphor without affecting the luminous efficiency of the phosphor.

[0019] Preferably, in step 3), sequentially adding the BX solution series to the base solution A means sequentially adding the BX solution series to the base solution A in an order in which the concentration of K2MnF6 increases sequentially. In this application, the BX solution series is added sequentially in an order in which the concentration of K2MnF6 increases sequentially, and the activator Mn 4+ A core is obtained in which the atomic percentage tends to increase radially from the inside to the outside, further improving the absorption rate of the phosphor to excitation light.

[0020] Preferably, in step 2), sampling the K2MnF6 series means sequentially sampling K2MnF6 whose mass increases in an arithmetic progression manner. Using K2MnF6 raw materials whose mass increases in an arithmetic progression manner, the Mn in the manufactured core 4+ The atomic percentage increases linearly and uniformly from the inside to the outside in the radial direction, which is advantageous for improving the absorption effect and conversion efficiency of the phosphor to excitation light. Optionally, the tolerance for the arithmetic progression of the mass is 0.1 to 0.3 g.

[0021] Preferably, the mass concentration of the H2MF6 solution is 10-15%, and the mass of K2MnF6 used for every 5-7.5 g of H2MF6 in the BX solution series is 0-3 g.

[0022] Preferably, the mass concentration of the hydrofluoric acid solution is 35-55%, and the volume of hydrofluoric acid solution used for each 15-25 g of salt A in the base solution A is 200-300 mL.

[0023] Preferably, the mass of the BX solution series added in step 3) is 100 to 1300 g, and the mass of the H2MF6 solution added to the core mixture is 5 to 200 g.

[0024] Preferably, the BX solution series and H2MF6 solution are added while being stirred at 10-50°C, and after stirring is complete, the supernatant is removed for washing and drying.

[0025] Preferably, the rate at which the BX solution series and the H2MF6 solution are added is 10 to 50 mL / s, and the stirring time is 2 to 5 hours.

[0026] Preferably, in the salt A, A is element K, i.e., the salt A is a potassium salt. Optionally, the salt A is potassium hydrogen fluoride.

[0027] Furthermore, the mass concentration of the hydrofluoric acid solution is 40% to 55%.

[0028] Preferably, in the H2MF6, M is Si, and the H2MF6 solution is an H2SiF6 solution, i.e., a fluorosilicic acid solution.

[0029] A third object of the present invention is to provide the use of any of the above-described degradation-preventing red phosphors or degradation-preventing red phosphors manufactured by any of the above-described manufacturing methods in the field of liquid crystal backlights or LED lighting.

[0030] A fourth object of the present invention is to provide a liquid crystal backlight comprising an excitation chip and a phosphor coated on the excitation chip, wherein the phosphor is any of the above-described degradation-preventing red phosphors, or the phosphor is a degradation-preventing red phosphor manufactured by any of the above-described manufacturing methods.

[0031] A fifth object of the present invention is to provide a lighting device comprising a light-emitting device, wherein the light-emitting device comprises an excitation chip and a phosphor coated on the excitation chip, wherein the phosphor is any of the above-described degradation-preventive red phosphors, or the phosphor is a degradation-preventive red phosphor manufactured by any of the above-described manufacturing methods. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram of the radial distribution of the relative content of Mn4+ in the degradation-preventing red phosphor particles of Examples 1 to 5. [Figure 2] These are SEM images of phosphor particles before cutting in a specific embodiment. The image on the left is a planar SEM image of the phosphor particles, and the image on the right is a 45° lateral SEM image of the phosphor particles after cutting, exposing a new cross-section. [Figure 3] This is a diagram showing the locations of the EDS spot scanning analysis performed on the degradation-preventing red phosphor particles in Example 1. [Figure 4] This is a diagram showing the location of the EDX scanning analysis performed on the degradation-preventing red phosphor particles in Example 5. [Figure 5] This shows the EDX scanning analysis results for the degradation-preventing red phosphor particles of Example 5. [Modes for carrying out the invention]

[0033] To further clarify the purpose, technical solutions, and advantages of this application, the application will be described in more detail below with reference to specific embodiments. The following embodiments are exemplary embodiments used to illustrate the principle of this application, namely, red phosphor A2M (1-x) F6:xMn 4+ A and M are preferably K and Si, respectively, and the synthetic raw materials are preferably potassium hydrogen fluoride, fluorosilicic acid, etc., but it should be understood that the present invention is not limited to these. Those skilled in the art can make various changes and improvements without departing from the spirit and essence of the present invention, and these changes and improvements are also considered to be within the scope of protection of the present invention.

[0034] For the sake of brevity, this application explicitly discloses only a few numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range, and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with other arbitrary upper limits to form an unspecified range. Furthermore, unless otherwise specified, each point or single value between the endpoints of a range shall be included in that range. Thus, each point or single value may, as its own lower or upper limit, be combined with any other point or single value, or with other lower or upper limits, to form an unspecified range.

[0035] K2SiF6:Mn 4+ While red phosphors offer the advantage of higher luminous efficiency compared to conventional red phosphors, their low moisture resistance makes them prone to performance degradation, affecting their effectiveness in LED lighting. Conventional red phosphors inevitably suffer negative impacts on luminous efficiency when attempting to improve moisture resistance, creating a strong demand for red phosphors that achieve both high moisture resistance and high luminous efficiency.

[0036] To solve the above problem, this application provides a degradation-resistant red phosphor, the degradation-resistant red phosphor having a core-shell structure, the core-shell structure comprising a core and a shell, the core and the shell being independently selected from a substance represented by chemical formula I, chemical formula I: A2M (1-x) F6:xMn 4+ In chemical formula I, A comprises at least one of Li, Na, K, Rb, and Cs, and M comprises at least one of Si, Ge, and Ti, where the innermost layer of the core is Mn 4+ The atomic percentage is a, and the outermost layer of the core is Mn 4+ The atomic percentage is b, where b > a, and Mn at each location within the particle of the core. 4+ The atomic percentage is x1, and the range of x values ​​is a ≤ x1 ≤ b, and the Mn of the shell. 4+The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.1%.

[0037] For example, in chemical formula I, 0 <x≦0.05である。

[0038] In some embodiments, x1 tends to increase from the inside to the outside in the radial direction of the core. In this application, the direction from the inside to the outside in the radial direction of the core refers to the direction starting from the innermost layer of the core and ending at the point on the outermost layer of the core closest to the innermost layer, and the innermost layer of the core refers to the first layer of core that is initially formed during the production of the degradation-preventing red phosphor, that is, the first layer of core formed by reacting the base solution A with the initially added BX solution. In the phosphor particles of this application, the region where the innermost layer of the core is located is the region with the lowest concentration of the activator.

[0039] In some specific embodiments, the core is divided into n layers from the inside to the outside in the radial direction, where n is an integer and the range of n is 5 ≤ ​​n ≤ 20, and Mn within the same layer 4+ The atomic percentages are the same, and the different interlayers are Mn from the inside out along the radial direction of the core. 4+ The atomic percentage shows an increasing trend.

[0040] In some specific examples, the lower limit of n is any value selected from 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, the upper limit of n is any value selected from 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and the range of values ​​for n is a range consisting of any of the values ​​selected from the lower and upper limits, respectively.

[0041] In some specific embodiments, the increasing trend is such that x1 increases linearly or non-linearly from the inside to the outside in the radial direction of the core.

[0042] In some specific embodiments, the increasing trend is such that x1 increases linearly and uniformly from the inside to the outside in the radial direction of the core. In this application, linear and uniform increase means that Mn increases from the inside to the outside in the radial direction of the core. 4+ The atomic percentages maintain the same linear increasing trend, for example, Mn in Example 1 of Figure 1. 4+ This is an increasing trend in the relative content, that is, between any two adjacent layers of the core, Mn 4+ The increasing trend of the atomic percentages is the same.

[0043] This application further provides a method for producing a degradation-resistant red phosphor for producing any of the above-mentioned degradation-resistant red phosphors, comprising: step 1) dissolving A salt in a hydrofluoric acid solution and referring to it as base solution A; step 2) dissolving the K2MnF6 series in equal masses of H2MF6 solution to prepare a series of BX solutions with different concentrations of K2MnF6; and sequentially adding the BX solution series to the base solution A, so that the concentration of K2MnF6 in the first BX solution added is the lowest, and the concentration of K2MnF6 in the last BX solution added is the lowest. Step 3) involves controlling the temperature to be as high as possible to obtain a core mixture, which is used for the production of the core, and then adding an H2MF6 solution to the core mixture and using it for the production of the shell, i.e., obtaining the degradation-preventing red phosphor, wherein the A salt is at least one selected from fluoride, hydrofluoric acid, sulfate, nitrate, bisulfate, carbonate, and bicarbonate of A, A is selected from Li, Na, K, Rb, and Cs, and in the H2MF6, M is selected from Si, Ge, and Ti.

[0044] In some exemplary examples, the fluoride of A may be selected from lithium fluoride, sodium fluoride, potassium fluoride, rubidium fluoride, and cesium fluoride; the hydrofluoric acid of A may be selected from LiHF2, NaHF2, KHF2, RbHF2, and CsHF2; the sulfate of A may be selected from Li2SO4, Na2SO4, K2SO4, Rb2SO4, and Cs2SO4; and the nitrate of A may be LiNO3 or NaNO3 The hydrogen sulfate of A may be selected from KNO3, RbNO3, and CsNO3, the carbonate of A may be selected from LiHSO4, NaHSO4, KHSO4, RbHSO4, and CsHSO4, the bicarbonate of A may be selected from Li2CO3, Na2CO3, K2CO3, Rb2CO3, and Cs2CO3, and the bicarbonate of A may be selected from LiHCO3, NaHCO3, KHCO3, RbHCO3, and CsHCO3.

[0045] In some exemplary embodiments, H2MF6 may be selected from H2SiF6, H2GeF6, and H2TiF6.

[0046] In some embodiments, sequentially adding the BX solution series to the base solution A in step 3) means sequentially adding the BX solution series to the base solution A in an order in which the concentration of K2MnF6 increases sequentially.

[0047] In some specific embodiments, the sampling of the K2MnF6 series in step 2) is performed with masses a1, a2, a3, ..., a n The purpose is to collect the K2MnF6 raw material, a1, a2, a3, ..., a n The expression shows a progressively increasing trend, n is an integer, and the range of n values ​​is 5 ≤ ​​n ≤ 20.

[0048] In some specific examples, the range of n values ​​is 10 ≤ n ≤ 20.

[0049] In some specific embodiments, the masses are a1, a2, a3, ..., a n The K2MnF6 raw materials are each dissolved in H2MF6 solution, and a series of BX solutions are prepared, with increasing concentrations of K2MnF6, named BX1, BX2, BX3, ..., BX n It is written as BX1, BX2, BX3, ..., BX n The concentration of K2MnF6 in the solution shows a progressively increasing trend.

[0050] In some specific examples, the range of the value of a1 is 0 ≤ a1 ≤ 0.01 g, and when a1 is 0, the mass of K2MnF6 increases from 0, and the concentration of K2MnF6 in the BX1 solution in the prepared BX solution series is 0.

[0051] In some specific embodiments, the BX solution series is added sequentially to the base solution A in an increasing order of concentration, such as BX1 to BX n The solutions are sequentially added to base solution A and reacted sequentially to produce a core. The core is divided into n layers radially from the inside out, and each time BX solution is added, it reacts with base solution A to form a new layer of the core.

[0052] In some specific embodiments, the mass of H2MF6 in the BX solution and H2MF6 solution added each time in step 3) is the same, and the number of times the H2MF6 solution is added to the core mixing system is 1 to 5 times.

[0053] In some specific examples, a n The range of values ​​is 2.5g ≤ a n The value is ≤3g.

[0054] In some specific examples, the mass concentration of the H2MF6 solution is 10-15%, and the mass of the H2MF6 solution is 40-60g, for example, the mass of the H2MF6 solution is 50g.

[0055] In some specific embodiments, the mass of salt A is 15 to 25 g.

[0056] In some specific examples, the mass concentration of the hydrofluoric acid solution is 35-55%, and the volume of the hydrofluoric acid solution is 200-300 mL, for example, the volume of the hydrofluoric acid solution is 250 mL.

[0057] In some specific embodiments, the washing is performed by sequentially adding an aqueous HF solution and anhydrous ethanol and stirring, with the mass concentration of the aqueous HF solution being 3-10%.

[0058] In some specific examples, the drying is performed at a temperature of 50-70°C.

[0059] Examples The technical solution of the present invention will be described below with reference to specific examples. All raw materials used in the following examples are from common commercially available products, and all devices or equipment used are purchased from conventional commercial sales channels.

[0060] Example 1 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction of the core, and the range of the value of x1 is 0 ≤ x1 ≤ 0.77%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for manufacturing the degradation-preventing red phosphor in this embodiment is: Step 1) involves dissolving 21 g of KHF2 in 250 mL of 40% hydrofluoric acid solution to prepare base solution A, Step 2) involves collecting the K2MnF6 series and dissolving each in 50g of 10% by mass fluorosilicic acid solution in increasing order of mass to prepare a series of BX solutions in which the concentration of K2MnF6 increases. The BX solution series is added sequentially to the base solution A in order of increasing concentration, and the number of additions is designated as A1, A2, A3, ..., A 16 The following steps were taken to obtain a core mixture system, which was used in the production of the core. Then, 50 g of a 10% by mass fluorosilicic acid solution was added to the core mixture system three times, with each addition being A 17 , A 18 , A 19 It is written that it is used in the manufacture of the shell (number of times added A1~A 19 Step 3) includes the following steps: (The mass of the K2MnF6 raw material contained in is shown in Table 1 below), (The process of adding the BX solution series and fluorosilicic acid solution is controlled to stir at 40°C, after stirring for 2 hours the supernatant is discarded, a 5% by mass aqueous HF solution is added and stirred and washed twice, then washed twice with anhydrous ethanol, and then dried under forced-air drying conditions at 60°C to obtain the degradation-preventing red phosphor of the present invention.

[0061] Example 2 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase from the inside to the outside in the radial direction of the core, and the range of x1 is 0 ≤ x1 ≤ 0.80%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 in that, in step 2), the K2MnF6 raw material whose mass increases is separately collected and a BX solution series is prepared, and in step 3), the mass of the K2MnF6 raw material contained in the BX solution series added is shown in Table 1 below.

[0062] Example 3 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase from the inside to the outside in the radial direction of the core, and the range of x1 is 0 ≤ x1 ≤ 0.82%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.02%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 in that, in step 2), the K2MnF6 raw material whose mass increases is separately collected and a BX solution series is prepared, and in step 3), the mass of the K2MnF6 raw material contained in the BX solution series added is shown in Table 1 below.

[0063] Example 4 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase from the inside to the outside in the radial direction of the core, and the range of x1 is 0 ≤ x1 ≤ 0.79%, and the Mn in the shell 4+The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 in that, in step 2), the K2MnF6 raw material whose mass increases is separately collected and a BX solution series is prepared, and in step 3), the mass of the K2MnF6 raw material contained in the BX solution series added is shown in Table 1 below.

[0064] Example 5 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase from the inside to the outside in the radial direction of the core, and the range of x1 is 0 ≤ x1 ≤ 0.81%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.02%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 in that, in step 2), the K2MnF6 raw material whose mass increases is separately collected and a BX solution series is prepared, and in step 3), the mass of the K2MnF6 raw material contained in the BX solution series added is shown in Table 1 below.

[0065] Example 6 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ And here, the innermost layer of the phosphor core is Mn 4+The atomic percentage is 0, and the outermost layer of the core is Mn 4+ The atomic percentage is 0.77%, and Mn is present at each location within the particles of the phosphor core. 4+ The atomic percentage of Mn in the shell is x1, and x1 is randomly distributed from the inside to the outside in the radial direction of the core, excluding the innermost and outermost layers of the core, and the range of x1 is 0 ≤ x1 ≤ 0.77%, and the Mn in the shell is 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 in that, in step 2), the K2MnF6 raw material whose mass increases is separately collected and a BX solution series is prepared, and in step 3), the mass of the K2MnF6 raw material contained in the BX solution series added is shown in Table 1 below.

[0066] Example 7 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Si (1-x) F6:xMn 4+ And here, the innermost layer of the phosphor core is Mn 4+ The atomic percentage is 0, and the outermost layer of the core is Mn 4+ The atomic percentage is 5%, and Mn is present at each location within the phosphor core particle. 4+ The atomic percentage of is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction, and the range of x1 is 0 ≤ x1 ≤ 5%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.1%.

[0067] Example 8 The red phosphor for preventing deterioration in this embodiment has a core-shell structure, and the core-shell structure includes a core and a shell. The core and the shell are independently selected from the substances represented by Chemical Formula I. Chemical Formula I: K2Si (1-x) F6:xMn 4+ wherein the atomic percentage of Mn in the innermost layer of the phosphor core is 0.1%, the atomic percentage of Mn in the outermost layer of the core is 0.3%, the atomic percentage of Mn at each location inside the particles of the phosphor core is x1, and x1 shows a tendency to linearly and uniformly increase from the inside to the outside in the radial direction. The range of the value of x1 is 0.1% ≤ x1 ≤ 0.3%. The atomic percentage of Mn in the shell is x2, and the range of the value of x2 is 0 ≤ x2 ≤ 0.01%.

[0068] Example 9 The red phosphor for preventing deterioration in this embodiment has a core-shell structure, and the core-shell structure includes a core and a shell. The core and the shell are independently selected from the substances represented by Chemical Formula I. Chemical Formula I: K2Si (1-x) F6:xMn 4+ wherein the atomic percentage of Mn in the innermost layer of the phosphor core is 0, the atomic percentage of Mn in the outermost layer of the core is 2%, the atomic percentage of Mn at each location inside the particles of the phosphor core is x1, and x1 shows a tendency to linearly and uniformly increase from the inside to the outside in the radial direction. The range of the value of x1 is 0 ≤ x1 ≤ 2%. The atomic percentage of Mn in the shell is x2, and the range of the value of x2 is 0 ≤ x2 ≤ 0.05%.

[0069] Example 10 The red phosphor for preventing deterioration in this embodiment has a core-shell structure, and the core-shell structure includes a core and a shell. The core and the shell are independently selected from the substances represented by Chemical Formula I. Chemical Formula I: K2Si (1-x) F6:xMn​​​​​​​​​​​​​​​​4+ And here, the innermost layer of the phosphor core is Mn 4+ The atomic percentage is 0, and the outermost layer of the core is Mn 4+ The atomic percentage is 0.5%, and Mn is present at each location within the phosphor core particle. 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction, and the range of x1 is 0 ≤ x1 ≤ 0.5%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%.

[0070] Example 11 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: Li2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction of the core, and the range of the value of x1 is 0 ≤ x1 ≤ 0.81%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 only in that, in step 1), Li2CO3 is used instead of KHF2 and dissolved in a hydrofluoric acid solution.

[0071] Example 12 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: Cs2Si (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction of the core, and the range of the value of x1 is 0 ≤ x1 ≤ 0.80%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 only in that CsF is used instead of KHF2 in step 1) and dissolved in a hydrofluoric acid solution.

[0072] Example 13 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, where chemical formula I: K2Ge (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core 4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction of the core, and the range of the value of x1 is 0 ≤ x1 ≤ 0.82%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this example differs from Example 1 only in that an H2GeF6 solution is used instead of a fluorosilicic acid solution in steps 2) and 3).

[0073] Example 14 The degradation-preventing red phosphor of this embodiment has a core-shell structure, the core-shell structure comprising a core and a shell, the core and shell being independently selected from a substance represented by chemical formula I, chemical formula I: K2Ti (1-x) F6:xMn 4+ Here, Mn at each location inside the particle of the core4+ The atomic percentage of Mn in the shell is x1, and x1 tends to increase linearly and uniformly from the inside to the outside in the radial direction of the core, and the range of the value of x1 is 0 ≤ x1 ≤ 0.81%, and the Mn in the shell 4+ The atomic percentage is x², and the range of x² is 0 ≤ x² ≤ 0.01%. The degradation-preventing red phosphor in this embodiment has an average particle size of 30 μm, where the average shell thickness is 1.8 μm. The method for producing the degradation-preventing red phosphor in this embodiment differs from Example 1 only in that an H2TiF6 solution is used instead of a fluorosilicic acid solution in steps 2) and 3).

[0074] Comparative Example 1 The phosphor in this comparative example differs from that in Example 1 only in that it contains only the core of the degradation-preventing red phosphor of Example 1 and does not contain the shell. In the method for producing the phosphor in this comparative example, in step 3), the BX solution series is added sequentially to the base solution A in an order of increasing concentration, with the number of additions being A1, A2, A3, ..., A 16 The number of times to add is A1~A 16 The mass of the K2MnF6 raw material contained in the following Table 1 is shown, and A1 to A in step 3) of Example 1) 16 The mass of the K2MnF6 raw material is the same as that of the corresponding K2MnF6 raw material, and the only difference from Example 6 is that fluorosilicic acid solution is not added after the BX solution is added.

[0075] Comparative Example 2 The phosphor of this comparative example has Mn at each location inside the particles of the core within the phosphor. 4+ The only difference from Example 1 is that the atomic percentage is x1, and x1 is uniformly distributed radially from the inside to the outside. The method for producing the phosphor in this comparative example involves, in step 2) taking 16 equivalent parts of K2MnF6 raw material, dissolving 1.35 g of each part in 50 g of a 10% by mass fluorosilicic acid solution to prepare a series of BX solutions with equal concentrations of K2MnF6, and in step 3) adding each of the BX solution series to base solution A, with the number of additions being A1, A2, A3, ..., A 16It is written as Mn 4+ The only difference from Example 1 is that a core is manufactured in which the atomic percentages are uniformly distributed, and the shell is manufactured in the same way as in Example 1.

[0076] Comparative Example 3 The phosphor in this comparative example differs from that of Comparative Example 2 only in that it contains only the core of the phosphor in Comparative Example 2 and does not contain the shell. The method for producing the phosphor in this comparative example differs from that of Comparative Example 2 in that, in step 3), after adding the BX solution series to the base solution A, the fluorosilicic acid solution is not added.

[0077] The mass of K2MnF6 in the BX solution series and fluorosilicic acid solution added in step 3) of Examples 1-6 and Comparative Example 1

[0078] [Table 1]

[0079] As can be seen from Table 1, Examples 1 to 5 used a K2MnF6 raw material that exhibited a gradually increasing mass to produce a series of BX solutions, which were then used to manufacture the core. In Example 1, the mass of the K2MnF6 raw material used to manufacture the core increased in an arithmetic progression manner with a tolerance of 0.18 g. In Examples 2 to 5, the increasing trend was non-linear. In Example 6, the mass of the K2MnF6 raw material in the BX solution added first and last during core production was a minimum of 0 g and a maximum of 2.70 g, respectively, and the mass of the K2MnF6 raw material in the remaining additions was controlled to be randomly arranged. In Comparative Example 1, the mass of the K2MnF6 raw material used to manufacture the core was the same as in Example 1, but no shell was manufactured.

[0080] Test Example 1 Using a FIB-SEM focused ion beam scanning electron microscope, the degradation-preventing red phosphors of Examples 1-5 were cut using dual ion beams, and EDS spectral analysis was performed from the core to the surface of the new surface. Taking Example 1 as an example, Figure 2 is an SEM image of the degradation-preventing red phosphor before cutting, where the left figure is a planar SEM image of the phosphor particles, and the right figure is a 45° lateral SEM image of the phosphor particles after cutting to expose the new cross-section. Figure 3 is a scanning position diagram of the EDS spot scanning analysis of the degradation-preventing red phosphor particles of Example 1. The radial distribution of Mn atomic percentage from the innermost layer of the core to the outermost layer of the shell of the degradation-preventing red phosphor particles of Examples 1-5 obtained by EDS spectroscopy is shown in Table 2 below.

[0081] Radial distribution table of Mn atomic percentages for Examples 1-5

[0082] [Table 2]

[0083] As can be seen from Table 2, the degradation-preventing red phosphors of Examples 1 to 5 are divided into 16 layers from the inside to the outside in the radial direction of the core, and the shell is divided into 3 layers from the inside to the outside in the radial direction. The percentage of Mn atoms shows an increasing trend from the inside to the outside in the radial direction of the core, and individual values ​​are equal to or slightly decrease from the previous value, but this does not affect the overall increasing trend of the percentage of Mn atoms in the radial direction of the core. Here, the innermost layer of the core does not contain Mn atoms and the percentage of Mn atoms is 0% in all cases, the percentage of Mn atoms in the outermost layer of the core is between 0.77 and 0.82%, and the percentage of Mn atoms in the shell is between 0 and 0.02%. Here, the percentage of Mn atoms in Example 1 increases linearly and uniformly overall in the radial direction of the core.

[0084] To more intuitively reflect the increasing trend in the Mn element content of Examples 1-5, the Mn in the degradation-preventing red phosphor particles of Examples 1-5 is shown. 4+Figure 1 shows a schematic diagram of the radial distribution of the relative content of Mn, where the content of the outermost layer of each example core is taken as the reference (denoted as 1.0), and the black circles in the image indicate the Mn content at different positions in the inner radial direction of the phosphor particles. 4+ The relative content is shown, and points where it cannot be obtained are indicated by white circles. As can be seen from Figure 1, the core of the degradation-preventing red phosphor particles in Examples 1-5 is Mn 4+ It does not contain Mn, and in the process of moving away from the body center and approaching the outermost layer of the core, 4+ The relative content of Mn in Example 1 shows an increasing trend, and here it is. 4+ The relative content of shows a linear and uniform increasing trend. Mn in the phosphor particles of Examples 1-5 4+ The relative content of Mn is highest in the outermost layer of the core, and then on the shell. 4+ The relative content approaches 0 or reaches 0.

[0085] Using a FIB-SEM focused ion beam scanning electron microscope, an EDX test was performed on the surface of the phosphor particles after cutting the degradation-preventing red phosphor particles of Example 5, from the core to the surface. The EDX scanning positions are shown in Figure 4, and the obtained EDX scanning analysis results are shown in Figure 5. From the scanning results, it can be seen that the degradation-preventing red phosphor particles show a tendency for the Mn content to increase in a gradient from the innermost layer of the core to the outermost layer of the core, and that the Mn content, which is the shell activator, tends to decrease sharply.

[0086] Test Example 2 Aging tests were performed on the phosphors of Examples 1-6 and Comparative Examples 1-3, and the luminous flux at 0, 250, 500, 750, and 1000 h for each example and comparative example was tested. Table 3 shows the test method and apparatus for the 1000-hour aging test in this application, and Table 4 shows the aging test data for the KSF phosphors produced in the examples and comparative examples. (Explanation: KSF-0 is the sample from Comparative Example 1, KSF-1 is the sample from Example 1, KSF-2 is the sample from Example 2, KSF-3 is the sample from Example 3, KSF-4 is the sample from Example 4, KSF-5 is the sample from Example 5, KSF-6 is the sample from Example 6, KSF-7 is the sample from Comparative Example 2, and KSF-8 is the sample from Comparative Example 3)

[0087] Test methods and apparatus for aging tests in Examples 1-6 and Comparative Examples 1-3

[0088] [Table 3]

[0089] Luminous flux and luminance ratio results for Examples 1-6 and Comparative Examples 1-3 in the aging test.

[0090] [Table 4]

[0091] As can be seen from Table 4, the LED devices made using the phosphors of Examples 1-6 and Comparative Example 1 had an initial luminous flux of 126.34lm to 128.35lm at 85°C and 85RH%, while the LED device using the phosphor of Comparative Example 2 had an initial luminous flux of only 117.48lm. Comparative Example 3, compared to this, had an initial luminous flux of 120.83lm. The core of Comparative Example 2 showed a 2.8% decrease in initial luminous flux after the addition of the shell. This invention demonstrates that by controlling the Mn content of the innermost and outermost layers of the core, the luminous efficiency of the phosphor is not affected even when a shell with a relatively low combined Mn atomic percentage is used. It was found to be advantageous in ensuring high luminous intensity. As the test time increased, the luminous flux of the LED device using the phosphor of Comparative Example 1 gradually decreased, with the luminance ratio decreasing by approximately 1% every 250 hours. After 1000 hours, the luminous flux was only 123.47 lm, and the luminance was only 96.2% of the initial luminance, a decrease of 3.8% compared to the previous year. However, the decrease in luminous flux of the LED devices corresponding to the degradation-preventing red phosphors of Examples 1 to 6 was small. Even after 1000 hours of high-temperature and high-humidity testing, the luminous flux was still maintained at 125.10 lm to 127.05 lm, the luminance still reached 98.9% to 99.2% of the initial luminance, and the luminance ratio level was maintained at almost 99%. This application is based on the principle that Mn 4+By providing a shell with an extremely low content of the substance, the phosphor core is covered, and assuming that this does not affect the phosphor's luminescence efficiency, the phosphor's moisture resistance and degradation prevention capabilities are significantly improved, allowing the phosphor to maintain high luminescence intensity even when used in harsh environments of high temperature and humidity for extended periods.

[0092] Furthermore, comparing Examples 1 to 5 laterally, Example 1 employs a method in which the percentage of Mn atoms increases linearly and uniformly throughout the radial direction of the core. The measured initial luminous flux was the highest at 128.21 lm, and in the aging test, the decrease in luminous flux was the lowest. After 1000 hours, the luminance ratio was still maintained at 99.2%, decreasing by only 1.8%. This invention is advantageous in ensuring the conversion efficiency of the phosphor by controlling the percentage of Mn atoms to increase linearly and uniformly in the radial direction of the core, reducing the impact of harsh environments on the luminous flux during long-term use after being combined with the shell, and ensuring higher luminous efficiency.

[0093] Test Example 3 The phosphor samples from Example 1, 7-10 were sealed in light bulbs using the method shown in Table 3 of Test Example 2, and the luminous flux of each sample was tested. The results are shown in Table 5 below.

[0094] Light flux results of the samples from Example 1 and Examples 7-10

[0095] [Table 5]

[0096] As can be seen from Table 5, the luminous flux of the phosphor samples in Examples 1 and 7-10 can reach between 119.35 and 128.21 lm, demonstrating strong luminescence performance. Here, the luminous flux of the phosphors in Examples 1, 9, and 10, where the difference in atomic percentage of activator between the outermost and innermost layers of the core is 0.5% to 2%, is 124.20 to 128.21 lm, which is an improvement over Examples 7 and 8. In this application, the Mn in the core... 4+It has been found that controlling the distribution of atomic percentage content is advantageous for improving the absorption efficiency of the phosphor and obtaining superior luminescence performance.

[0097] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Those skilled in the art can easily envision modifications or substitutions within the technical scope disclosed herein, and these are included within the scope of protection of the present disclosure. Accordingly, equivalent modifications by the claims of the present disclosure are within the scope covered by the present disclosure.

[0098] [Cross-reference of related applications] This application claims priority to the Chinese patent application filed on June 25, 2023, application number 202310724565.3, with the title of the invention "Degradation-preventing red phosphor, method for manufacturing the same, and use thereof," and the entirety of that application is referred to hereby.

Claims

1. A degradation-preventing red phosphor having a core-shell structure, wherein the core-shell structure includes a core and a shell, and the core and the shell are independently selected from a substance represented by chemical formula I. A ２ M （１－ｘ） F ６ : xMn ４＋ Chemical formula I In chemical formula I, A contains at least one of Li, Na, K, Rb, and Cs, and M contains at least one of Si, Ge, and Ti. Here, the Mn in the innermost layer of the core ４＋ has an atomic percentage of a, and the Mn in the outermost layer of the core ４＋ has an atomic percentage of b, where b > a, and the Mn at each location inside the particles of the core ４＋ has an atomic percentage of x １ , and the range of the value of x1 is a ≤ x １ ≤ b. Mn in the aforementioned shell ４＋ The atomic percentage is x ２ and x ２ The range of values ​​is 0 ≤ x ２ ≤0.1%, A degradation-preventing red phosphor characterized in that b > x² in the aforementioned phosphor.

2. x １ The degradation-preventing red phosphor according to claim 1, characterized in that it shows an increasing tendency from the inside to the outside in the radial direction of the core.

3. The degradation-preventing red phosphor according to claim 1, characterized in that, in the core, the range of the value of a is 0 ≤ a ≤ 0.1%, and the range of the value of b is 0.3% ≤ b ≤ 5%.

4. The degradation-preventing red phosphor according to claim 3, characterized in that, in the core, the range of the value of a is 0 ≤ a ≤ 0.01%, and the range of the value of b is 0.5% ≤ b ≤ 1.5%.

5. In the aforementioned phosphor, 0 ≤ x ２ The degradation-preventing red phosphor according to claim 1, characterized in that / b ≤ 1 / 10.

6. The degradation-preventing red phosphor according to claim 1, characterized in that the average particle size of the degradation-preventing red phosphor is 5 to 40 μm, and the average thickness of the shell is 0.1 to 2 μm.

7. Step 1) involves dissolving salt A in hydrofluoric acid solution and referring to this as base solution A, K ２ MnF ６ Each in the series is H of equal mass ２ MF ６ Dissolve in solution, K ２ MnF ６ Step 2) prepares a series of BX solutions with different concentrations, The BX solution series is added sequentially to the base solution A, and the K of the first BX solution added ２ MnF ６ The concentration of was made the lowest, and the K of the BX solution added last was the lowest. ２ MnF ６ The concentration of is controlled to be as high as possible to obtain a core mixture system, which is used in the production of the core, and H is added to the core mixture system. ２ MF ６ Step 3) adds a solution and uses it to manufacture the shell, i.e., to obtain the degradation-preventing red phosphor, The A salt is at least one selected from fluoride, hydrofluoric acid, sulfate, nitrate, hydrogen sulfate, carbonate, and bicarbonate of A, and A is one selected from Li, Na, K, Rb, and Cs, and the H ２ MF ６ A method for producing a degradation-preventive red phosphor according to any one of claims 1 to 6, characterized in that M is selected from Si, Ge, and Ti.

8. Step 3) Adding the BX solution series sequentially to the base solution A means that the BX solution series is K ２ MnF ６ The method for producing a degradation-preventing red phosphor according to claim 7, characterized in that the concentration of is added sequentially to the base solution A in an order in which it increases sequentially.

9. Step 2) In step K ２ MnF ６ Collecting a series of samples is possible if the mass increases in the manner of an arithmetic progression. ２ MnF ６ The method for producing a degradation-preventive red phosphor according to claim 8, characterized in that the materials are collected sequentially.

10. The aforementioned H ２ MF ６ The mass concentration of the solution is 10-15%, and in the BX solution series, 5 g of H ２ MF ６ K used in each ２ MnF ６ Its mass is 0 to 3 g. The method for producing a degradation-preventive red phosphor according to claim 7, characterized in that the mass concentration of the hydrofluoric acid solution is 35 to 55%, and the volume of hydrofluoric acid solution used for each 15 to 25 g of salt A in the base solution A is 200 to 300 mL.

11. The mass of the BX solution series added in step 3) is 100 to 1300 g, and the H added to the core mixing system ２ MF ６ The method for producing a degradation-preventing red phosphor according to claim 7, characterized in that the mass of the solution is 5 to 200 g.

12. Use of a degradation-preventing red phosphor according to any one of claims 1 to 6 in the field of liquid crystal backlights or LED lighting.

13. The device comprises an excitation chip and a phosphor coated on the excitation chip, The liquid crystal backlight is characterized in that the phosphor is a degradation-preventing red phosphor according to any one of claims 1 to 6.

14. Including a light-emitting device, The light-emitting device includes an excitation chip and a phosphor coated on the excitation chip. The lighting device is characterized in that the phosphor is a degradation-preventing red phosphor according to any one of claims 1 to 6.

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