Preparation Method of Spherical Nitride Phosphor, Spherical Nitride Phosphor and Its Application

Abstract

The present application discloses a preparation method of spherical nitride phosphor, the spherical nitride phosphor and its application. The preparation method of the spherical nitride phosphor includes: (1) weighing Sr source, Ca source, Al source, Si source and Eu source according to the chemical dosage ratio of Sr 1‑x Ca x AlSiN3:Eu 2+ , mixing to obtain a mixture; (2) performing multi-stage calcination on the mixture under a protective atmosphere to obtain a calcined product; (3) dispersing the calcined product to obtain the spherical nitride phosphor. The spherical nitride phosphor prepared by the preparation method of the present application has good morphology uniformity, small particle size distribution and relatively smooth surface. At the same time, it has high target shooting concentration and good luminous efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of luminescent materials, and in particular, to a preparation method of spherical nitride phosphor, the spherical nitride phosphor, and their applications. Background Art

[0002] Currently, the combination of blue GaN chips and Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ) phosphor and red nitride phosphor has become the current mainstream lighting source. With the development of the lighting industry, the industry has put forward higher requirements for phosphors: high luminous efficiency, high thermal stability, high concentration, excellent morphology, etc. The nitride raw materials for synthesizing nitride red phosphors have strong covalent bonds and low diffusion coefficients, and the reaction needs to be carried out at higher temperatures and pressures. In the traditional preparation process, there are serious hard agglomerations in the sintering necks between the nitride red phosphor powder particles, the particle growth orientations are different, the particle size and morphology uniformity are poor, and the surface of the particles is easily damaged after crushing treatment, generating a large number of defects and reducing the luminous efficiency; at the same time, it will also cause the particle concentration to become worse, resulting in a significant decrease in the yield of the packaging target concentration.

[0003] The prior art discloses the preparation of nitride red phosphors by the high-temperature solid-phase method. At high temperatures, through the self-diffusion and mutual diffusion of interfacial ions, the original chemical bonds are broken and new bonds are formed to generate new substances. This method requires high temperatures, long times, and uneven heating, and the obtained powder has poor morphology uniformity, large particle distribution, and has an adverse effect on the packaging color coordinates and target concentration of the light-emitting device.

[0004] The prior art also discloses the preparation of nitride red phosphors by the secondary sintering method, which can reduce the reaction synthesis temperature and reduce powder agglomeration, but the ability to control the morphology of the phosphor is still limited. In addition, in the hydrothermal synthesis and sol-gel methods, the target solution after being mixed evenly is sintered at a low temperature to obtain a precursor, and then the precursor material is sintered at a high temperature to synthesize the target product. This method has a relatively low synthesis temperature, and the synthesized phosphors usually have the advantages of uniform morphology, fine particle size, and concentrated particle size distribution. However, its process operation is cumbersome, the synthesis cycle is long, the efficiency and output are low, and the luminous efficiency of the synthesized phosphor is low, which limits the application of this type of method in industrial production. Summary of the Invention

[0005] In view of this, the present application provides a preparation method of spherical nitride phosphor. The spherical nitride phosphor prepared by the preparation method of the present application has good morphology uniformity, small particle size distribution, and a relatively smooth surface. At the same time, it has good luminous efficiency and high target concentration.

[0006] In a first aspect, the present application provides a method for preparing a quasi-spherical nitride phosphor, and the preparation method includes the following steps: (1) Weigh Sr 1-x Ca x AlSiN 3 :Eu 2+ source, Ca source, Al source, Si source and Eu source according to the stoichiometric ratio, mix them to obtain a mixture; (2) Under a protective atmosphere, perform multi-stage calcination on the mixture to obtain a calcined product; (3) Disperse the calcined product to obtain the quasi-spherical nitride phosphor.

[0007] In some embodiments, in step (1), the mass ratio of the Sr source, Ca source, Al source, Si source and Eu source is:

[0008] (40% - 50%):(0.5% - 5%):(20% - 25%):(25% - 30%):(0.001% - 5%).

[0009] Among them, the Sr source is a nitride containing Sr element, the Ca source is a nitride containing Ca element, the Al source is a nitride containing Al element, the Si source is a nitride containing Si element, and the Eu source is a nitride containing Eu element.

[0010] In some embodiments, in step (2), the multi-stage calcination includes: setting a constant temperature platform at 1200 - 1500 °C in the first stage, setting the pressure maintaining pressure at 1 - 5 Mpa, and performing constant temperature calcination for 1 - 10 h; the first stage is the starting stage of the reaction. Controlling the reaction temperature, pressure maintaining pressure and calcination time in the first stage within the above ranges is beneficial to the growth of powder particles with a suitable particle size distribution. Exemplarily, the temperature of the constant temperature platform in the first stage is 1200 °C, 1250 °C, 1300 °C, 1350 °C, 1400 °C, 1450 °C, 1500 °C or a range composed of any two of the above values. The pressure maintaining pressure in the first stage is 1 Mpa, 2 Mpa, 3 Mpa, 4 Mpa, 5 Mpa or a range composed of any two of the above values. The calcination time in the first stage is 1 h, 3 h, 5 h, 6 h, 7 h, 8 h, 10 h or a range composed of any two of the above values.

[0011] In the second stage, a constant temperature platform is set at 1500 - 1800 °C, the pressure holding pressure is set at 5 - 20 Mpa, and it is baked at a constant temperature for 1 - 10 h; the second stage is the core stage of crystal growth. The appropriate pressure holding pressure increases the saturated vapor pressure between grains, making it not easy for the crystals to grow by fusion. At the same time, the appropriate pressure holding pressure increases the melting point of the phase and reduces the liquid phase amount, thereby controlling the oriented growth of particle sintering. At the same time, the crystal grows under the temperature condition of 1500 - 1800 °C. The cooperation of the appropriate reaction temperature, relatively high pressure holding pressure, and appropriate baking time can, on the one hand, inhibit the uniaxial oriented growth of the crystal, so that the prepared spherical nitride phosphor has a uniform and spherical morphology, a concentrated particle size distribution, which is beneficial to improving the targeting concentration of the light-emitting device; on the other hand, crystals with appropriate particle sizes can be obtained. Exemplarily, the temperature of the constant temperature platform in the second stage is 1500 °C, 1550 °C, 1600 °C, 1650 °C, 1700 °C, 1750 °C, 1800 °C or the range composed of any two of the above values. The pressure holding pressure in the second stage is 5 Mpa, 8 Mpa, 9 Mpa, 10 Mpa, 12 Mpa, 14 Mpa, 16 Mpa, 18 Mpa, 20 Mpa or the range composed of any two of the above values. The baking time in the second stage is 1 h, 3 h, 5 h, 6 h, 7 h, 8 h, 10 h or the range composed of any two of the above values.

[0012] In the third stage, a constant temperature platform is set at 1800 - 2000 °C, the pressure holding pressure is set at 5 - 20 Mpa, and it is baked at a constant temperature for 1 - 10 h. The third stage is the surface modification stage of the phosphor powder. The appropriate repair temperature, appropriate pressure holding pressure combined with a certain baking time can promote the repair of defects on the surface of the powder particles, so that the prepared phosphor powder particles have a higher sphericity and better morphology. Exemplarily, the temperature of the constant temperature platform in the third stage is 1800 °C, 1850 °C, 1900 °C, 1950 °C, 2000 °C or the range composed of any two of the above values. The pressure holding pressure in the second stage is 5 Mpa, 8 Mpa, 9 Mpa, 10 Mpa, 12 Mpa, 14 Mpa, 16 Mpa, 18 Mpa, 20 Mpa or the range composed of any two of the above values. The baking time in the second stage is 1 h, 3 h, 5 h, 6 h, 7 h, 8 h, 10 h or the range composed of any two of the above values.

[0013] In some embodiments, in the second stage, a constant temperature platform is set at 1650 - 1700 °C, the pressure holding pressure is set at 8 - 10 Mpa, and it is baked at a constant temperature for 6 - 10 h. In the third stage, a constant temperature platform is set at 1850 - 1950 °C, the pressure holding pressure is set at 8 - 10 Mpa, and it is baked at a constant temperature for 4 - 6 h.

[0014] In some embodiments, in step (2), the protective atmosphere is a pure nitrogen atmosphere or a nitrogen-hydrogen mixed gas atmosphere. When the protective atmosphere is a nitrogen-hydrogen mixed gas atmosphere, the volume ratio of nitrogen to hydrogen is 10-95:5-90.

[0015] In some embodiments, in step (3), the dispersion treatment includes: crushing the calcined product and sieving it to obtain a sieved intermediate product; placing the intermediate product in deionized water, stirring, filtering by suction, washing until the conductivity is less than 10 μs / cm, and drying to obtain the spherical nitride phosphor. Among them, the stirring time is 20-30 min. Exemplarily, the stirring time is 20 min, 23 min, 25 min, 28 min, 30 min or the range composed of any two of the above values. The crushing / sieving process can refer to the conventional technical means in the art, and this application does not make any limitations.

[0016] Second, this application provides a spherical nitride phosphor, and the chemical structural formula of the spherical nitride phosphor is Sr 1-x Ca x AlSiN 3 :Eu 2+ ; wherein, the value range of x is 0≤x≤1.

[0017] In some embodiments, the particle size range of the spherical nitride phosphor is 5 μm to 40 μm, the sphericity is 0.55 to 0.7, D10 is 11 μm to 13 μm, D50 is 21 μm to 22 μm, D90 is 33 μm to 35 μm, and the particle size concentration [(D90-D10) / D50] is 0.9-1.2. Among them, the particle size range means that the particle size of the finest phosphor particles is 5 μm and the particle size of the coarsest phosphor particles is 40 μm.

[0018] In some embodiments, the spherical nitride phosphor is prepared according to the above preparation method.

[0019] Third, this application provides a light-emitting device, and the light-emitting device includes a fluorescent layer and a blue light chip, and the fluorescent layer includes the spherical nitride phosphor prepared by the above preparation method.

[0020] Fourth, this application provides a white LED lighting device, and the white LED lighting device includes the above light-emitting device. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 SEM image of Example 1 of the present application;

[0023] Figure 2 SEM image of Comparative Example 1 of the present application;

[0024] Figure 3 SEM image of Example 3 of the present application;

[0025] Figure 4 SEM image of Comparative Example 3 of the present application;

[0026] Figure 5 Target shooting diagram of Example 1 of the present application;

[0027] Figure 6 Target shooting diagram of Comparative Example 1 of the present application. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the following further details the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] The following further illustrates the present application through examples and comparative examples.

[0030] Other fluorescent materials used in the examples and comparative examples of the present application can all be purchased through commercial channels.

[0031] (1) Preparation of spherical nitride fluorescent powder

[0032] Example 1

[0033] The raw materials were weighed according to the mass ratio of strontium nitride 46.97%, calcium nitride 3.93%, aluminum nitride 20.37%, silicon nitride 28.52%, and europium oxide 0.21%. The above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, loaded into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1200°C under the protection of a pure nitrogen atmosphere, the pressure was increased to 2Mpa, and the constant temperature roasting time was 6 hours, and then heated to 1700°C, the pressure was increased to 9Mpa, and the constant temperature roasting time was 6 hours; then heated to 1900°C, and the constant temperature roasting time was 4 hours, the obtained nitride phosphor was crushed and sieved, the sieved nitride phosphor was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 8.56μs / cm, and dried to obtain a spherical nitride phosphor. The test results are shown in Table 1.

[0034] Comparative Example 1

[0035] The raw materials were weighed according to the mass ratio of strontium nitride 46.97%, calcium nitride 3.93%, aluminum nitride 20.37%, silicon nitride 28.52%, and europium oxide 0.21%. The above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, put into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1900°C under the protection of a pure nitrogen atmosphere, and the pressure was increased to 2Mpa. The constant temperature roasting time was 12 hours. The obtained nitride phosphor powder was crushed and sieved, and the sieved nitride phosphor powder was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 7.44μs / cm. After drying, the nitride phosphor product was obtained. The test results are shown in Table 1.

[0036] Figure 1 This is the SEM image of Example 1 of the present application. Figure 2 It is the SEM image of Comparative Example 1 of the present application. It can be seen that the morphology of Example 1 is spherical, the particle size is relatively uniform, the particle size distribution is small, and the surface is relatively smooth. The light efficiency is significantly higher than that of Comparative Example 1, while the morphology of Comparative Example 1 is rod-shaped, with different lengths and a larger particle size distribution. The data are shown in Table 1.

[0037] Figure 5 This is the target shooting diagram of Example 1 of the present application. Figure 6 This is the target shooting diagram of Comparative Example 1 of this application. Figure 5 The yield rate of 3rd-order target shooting is 93.2%, and the yield rate of 5th-order target shooting is 99.2%; Figure 6 The 3rd-order target yield is 90.1%, and the 5th-order target yield is 98.5%. It can be seen that compared with Comparative Example 1, the 3rd-order yield of Example 1 is improved by 3.1%, and the 5th-order yield is improved by 0.7%.

[0038] Embodiment 2:

[0039] The raw materials were weighed according to the mass ratio of strontium nitride 47.58%, calcium nitride 2.76%, aluminum nitride 22.9%, silicon nitride 26.12%, and europium nitride 0.64%. The above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, loaded into a crucible, and quickly moved into a gas pressure sintering furnace. Then, the temperature was gradually raised to 1300°C under the protection of a nitrogen-hydrogen mixed gas (volume ratio 95:5), the pressure was increased to 5Mpa, and the constant temperature roasting time was 4 hours. Then, the temperature was raised to 1800°C, the pressure was increased to 12Mpa, and the constant temperature roasting time was 5 hours; then, the temperature was raised to 1950°C, and the constant temperature roasting time was 4 hours. The obtained nitride phosphor was crushed and sieved, and the sieved nitride phosphor was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 8.56μs / cm. After drying, a spherical nitride phosphor was obtained. The test results are shown in Table 1.

[0040] Comparative Example 2

[0041] The raw materials were weighed according to the mass ratio of strontium nitride 47.58%, calcium nitride 2.76%, aluminum nitride 22.9%, silicon nitride 26.12%, and europium nitride 0.64%, and the above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, put into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1950°C under the protection of nitrogen and hydrogen mixed gas (volume ratio 95:5), the pressure was increased to 5Mpa, and the constant temperature roasting time was 12 hours. The obtained nitride phosphor powder was crushed and sieved, and the sieved nitride phosphor powder was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 6.25μs / cm. After drying, the nitride phosphor product was obtained. The test results are shown in Table 1.

[0042] Embodiment 3:

[0043] The raw materials were weighed according to the mass ratio of strontium nitride 43.61%, calcium nitride 4.83%, aluminum nitride 22.91%, silicon nitride 26.12%, and europium fluoride 2.53%, and the above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, loaded into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1400°C under the protection of a pure nitrogen atmosphere, the pressure was increased to 3Mpa, and the constant temperature roasting time was 3 hours, and then heated to 1600°C, the pressure was increased to 15Mpa, and the constant temperature roasting time was 2 hours; then heated to 1850°C, and the constant temperature roasting time was 6 hours, the obtained nitride phosphor was crushed and sieved, and the sieved nitride phosphor was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 8.09μs / cm, and dried to obtain a spherical nitride phosphor. The test results are shown in Table 1.

[0044] Comparative Example 3

[0045] The raw materials were weighed according to the mass ratio of strontium nitride 43.61%, calcium nitride 4.83%, aluminum nitride 22.91%, silicon nitride 26.12%, and europium fluoride 2.53%, and the above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, put into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1850°C under the protection of a pure nitrogen atmosphere, and the pressure was increased to 3Mpa, and the constant temperature roasting time was 12 hours. The obtained nitride phosphor powder was crushed and sieved, and the sieved nitride phosphor powder was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 5.11μs / cm, and the nitride phosphor product was obtained after drying. The test results are shown in Table 1.

[0046] Figure 3 is the SEM picture of Example 3, Figure 4 This is the SEM image of Comparative Example 3. It can be seen that the morphology of Example 3 is spherical, the particle size is relatively uniform, the particle size distribution is small, and the surface is relatively smooth. The light efficiency is significantly higher than that of Comparative Example 3, while the morphology of Comparative Example 3 is rod-shaped, with different lengths and a larger particle size distribution. The data are shown in Table 1.

[0047] Embodiment 4:

[0048] The raw materials were weighed according to the mass ratio of strontium nitride 47.31%, calcium nitride 3.22%, aluminum nitride 22.27%, silicon nitride 25.41%, and europium chloride 1.78%. The above raw materials were fully mixed in a nitrogen atmosphere for 3 hours, loaded into a crucible, and quickly moved into a gas pressure sintering furnace, and then gradually heated to 1500°C under the protection of nitrogen and hydrogen mixed gas (volume ratio 90:10), the pressure was increased to 3Mpa, and the constant temperature roasting time was 4 hours, and then heated to 1750°C, the pressure was increased to 7Mpa, and the constant temperature roasting time was 4 hours; then heated to 1950°C, and the constant temperature roasting time was 4 hours, the obtained nitride phosphor was crushed and sieved, the sieved nitride phosphor was placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity was 6.17μs / cm, and dried to obtain a spherical nitride phosphor. The test results are shown in Table 1.

[0049] Comparative Example 4

[0050] Weigh the raw materials according to the mass ratio of strontium nitride 47.31%, calcium nitride 3.22%, aluminum nitride 22.27%, silicon nitride 25.41%, and europium chloride 1.78%, fully mix the above raw materials in a nitrogen atmosphere for 3 hours, put them into a crucible, quickly move them into a gas pressure sintering furnace, and then gradually heat them to 1950°C under the protection of nitrogen and hydrogen mixed gas (volume ratio 90:10), increase the pressure to 3Mpa, and calcine them at a constant temperature for 12 hours. The obtained nitride phosphor powder is crushed and sieved, and the sieved nitride phosphor powder is placed in deionized water and stirred for 30 minutes, then filtered, and finally washed until the conductivity is 6.57μs / cm. After drying, the nitride phosphor product can be obtained. The test results are shown in Table 1.

[0051] (II) Test of spherical nitride phosphors

[0052] (1) Phosphor particle size: tested by laser particle size analyzer.

[0053] (2) Sphericity of particles: According to the sphericity formula:

[0054]

[0055] Where Vp is the particle volume and Sp is the particle surface area. The total volume of the tested powder particles is measured by the liquid displacement method, and the total specific surface area of ​​the powder particles is measured by a laser particle size analyzer, and the average sphericity of the particles can be calculated.

[0056] The phosphors prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were packaged with YAG (Y3Al5O12: Ce3+) and a blue light chip, and a light efficiency test was performed. The test results are shown in Table 1.

[0057] Table 1

[0058] Group D10 D50 D90 Granularity distribution coefficient Sphericity Light efficiency Example 1 12.2 21.5 33.5 0.99 0.65 101.5％ Comparative Example 1 10.2 21.8 40.2 1.38 0.11 100.0％ Example 2 11.5 21.2 33.1 1.02 0.58 101.2％ Comparative Example 2 10.0 21.5 40.6 1.42 0.08 100.0％ Example 3 11.9 21.4 33.9 1.03 0.57 101.4％ Comparative Example 3 10.2 21.3 39.6 1.38 0.08 100.0％ Example 4 11.6 21.7 34.2 1.04 0.55 101.4％ Comparative Example 4 10.2 21.9 41.5 1.43 0.06 100.0％

[0059] It can be seen from Table 1 that the particle size distribution coefficient of the quasi-spherical nitride phosphor prepared in the present application is significantly reduced when the D50 value of the powder particles is similar to that of the comparative example. The particle size distribution coefficients of the embodiments are all around 1.0, while the particle size distribution coefficients of the comparative examples are all around 1.4. The smaller the particle size distribution coefficient, the higher the target concentration. Figure 5 , and the spherical nitride phosphor prepared by the preparation method of the present application has better luminous efficiency.

[0060] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A preparation method of a quasi-spherical nitride phosphor, characterized in that, it comprises the following steps: (1) According to Sr 1-x Ca x AlSiN 3 :Eu 2+ Weigh the Sr source, Ca source, Al source, Si source and Eu source according to the chemical dosage ratio, and mix them to obtain a mixture; wherein, the value range of x is 0 < x < 1; (2) Under a protective atmosphere, subjecting the mixture to multi-stage calcination to obtain a calcined product; (3) Subjecting the calcined product to dispersion treatment to obtain the quasi-spherical nitride phosphor; In step (2), the multi-stage calcination includes: In the first stage, set a constant temperature platform at 1200~1500 °C, set the pressure maintaining pressure at 1~5 Mpa, and perform isothermal calcination for 1~10 h; In the second stage, set a constant temperature platform at 1500~1800 °C, set the pressure maintaining pressure at 5~20 Mpa, and perform isothermal calcination for 1~10 h; In the third stage, set a constant temperature platform at 1800~2000 °C, set the pressure maintaining pressure at 5~20 Mpa, and perform isothermal calcination for 1~10 h.

2. The preparation method according to claim 1, characterized in that, In the second stage, set a constant temperature platform at 1650~1700 °C, set the pressure maintaining pressure at 8~10 Mpa, and perform isothermal calcination for 6~10 h; In the third stage, set a constant temperature platform at 1850~1950 °C, set the pressure maintaining pressure at 8~10 Mpa, and perform isothermal calcination for 4~6 h.

3. The preparation method according to claim 1, characterized in that, at least one of the following conditions is satisfied: Condition I: In step (1), the mass ratio of the Sr source, Ca source, Al source, Si source and Eu source is: (40%~50%):(0.5%~5%):(20%~25%):(25%~30%):(0.001%~5% )； Condition II: In step (2), the protective atmosphere is a pure nitrogen atmosphere or a nitrogen-hydrogen mixed gas atmosphere; When the protective atmosphere is a nitrogen-hydrogen mixed gas atmosphere, the volume ratio of nitrogen to hydrogen is 10~95:5~90.

4. The preparation method according to claim 1, characterized in that, In step (3), the dispersion treatment includes: Crushing the calcined product and sieving it to obtain a sieved intermediate product; Placing the intermediate product in deionized water, stirring, filtering by suction, washing until the conductivity is less than 10 μs / cm, and drying to obtain the quasi-spherical nitride phosphor.

5. A quasi-spherical nitride phosphor, characterized in that, The chemical structural formula of the spherical nitride phosphor is Sr 1-x Ca x AlSiN 3 :Eu 2+ ; where the value range of x is 0 < x < 1; the quasi-spherical nitride phosphor is prepared by the preparation method according to any one of claims 1 to 4.

6. The quasi-spherical nitride phosphor according to claim 5, characterized in that, the particle size range of the quasi-spherical nitride phosphor is 5 μm~40 μm, the sphericity is 0.55~0.7, D10 is 11 μm~13 μm, D50 is 21 μm~22 μm, and D90 is 33 μm~35 μm.

7. A light-emitting device, characterized in that, the light-emitting device includes a fluorescent layer and a blue light chip; the fluorescent layer includes the quasi-spherical nitride phosphor prepared by the preparation method according to any one of claims 1 to 4; or, the fluorescent layer includes the quasi-spherical nitride phosphor according to claim 5 or 6.

8. A white LED lighting device, characterized in that, the white LED lighting device includes the light-emitting device according to claim 7.

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