A method for obtaining nanoscale nitride fluorescent materials

Abstract

The application relates to a method for obtaining a nanoscale nitride fluorescent material, belonging to the field of fluorescent materials, and comprising the following steps: uniformly mixing Ca m Si alloy, EuSi alloy and AlN powder are uniformly mixed in a molar ratio of (1-x):x:1 under a protective atmosphere, high-temperature sintering is carried out under an ammonia atmosphere, grinding treatment is carried out, ultrasonic treatment is carried out after mixing with an oxalic acid solution, filtration is carried out, and drying is carried out; the nanoscale nitride fluorescent material Ca x Eu 1‑x AlSiN3, 0.02<=x<=0.08, D50 median particle size 80-100 nm; under the excitation of 450 nm light, the main peak of the emission spectrum is 670-710 nm, and the quantum efficiency is 50%-70%. In the preparation step, non-stoichiometric raw materials are specially used to prepare the nanoscale nitride fluorescent material, and under relatively mild and non-ball milling synthesis conditions, a nanoscale nitride fluorescent material for Mini LED device packaging is obtained.

Description

Technical Field

[0001] This invention relates to the field of fluorescent materials, and more particularly to a method for obtaining nanoscale nitride fluorescent materials. Background Technology

[0002] Mini LED display technology is a novel backlighting technology that uses light-emitting chips with planar dimensions between 50 μm and 200 μm, smaller than traditional LEDs. This means that more LED units can be integrated within the same area, resulting in higher resolution, brightness, contrast, and a wider color gamut. As is well known, traditional LED packaging technology involves mixing fluorescent materials (particles) with silicone and then coating them onto the surface of the LED chip. Traditional LED chips are typically millimeter-sized, and the fluorescent materials encapsulated on the LED chip are often synthesized using high-temperature solid-state synthesis technology, as described in document 1 (Haohao Wang, Yujie Liu, Xudong Zhu, Liangshu Wei, Xiping Jiang, Yong Chen, Langkai Li, Preparation of CaAlSiN3:Eu 2+ The median D50 particle size disclosed in "Red-emitting phosphor by a two-step method for solid-state lighting applications, Ceramics International, 2020, 46, 14:23035-23040" is typically ~10 μm. This means that for millimeter-sized traditional LED chips, the number of phosphor particles encapsulated on the chip is considerable, on the order of tens of thousands (millimeter-sized chip versus ~10 μm phosphor particles). Therefore, even if there are differences in luminescence performance between phosphor particles, statistically, these differences have no decisive impact on the final LED package performance. In other words, for traditional LED packaging, the particle size of the phosphor material has little impact on the final luminescence performance of the LED product.

[0003] However, for Mini LED display technology, since the planar size of Mini LED chips ranges from 50 μm to 200 μm, when using phosphor materials with a median D50 particle size of ~10 μm for encapsulation, the number of phosphor material particles encapsulated on the Mini LED chip is drastically reduced to several hundred (comparing micrometer-sized chips to ~10 μm phosphor material particles). At this point, the difference in luminous performance between the phosphor material particles will cause fluctuations in the luminous performance of the individual encapsulated Mini LED device, ultimately leading to color differences between Mini LED display modules composed of multiple Mini LED devices. To ensure the performance of Mini LED display devices, reducing the median D50 particle size of the phosphor material is clearly a more feasible approach without changing the Mini LED chip size.

[0004] One method to reduce the median D50 particle size of fluorescent materials is ball milling, which grinds existing fluorescent materials with a median D50 particle size of approximately ~10 μm to the submicron or nanometer scale. For example, document 2 (Li Shuxing, Xie Rongjun, A high-brightness, high-external-quantum-efficiency red mini-LED and its preparation method, CN114447190A) discloses a method for preparing micro-nano-level red fluorescent materials using ball milling, centrifugation, and acid washing. Ultimately, commercial nitride red phosphors (Sr,Ba)2Si5N8:Eu with a D50 of 11.5 μm can be ball milled to a median D50 particle size of 0.1 μm. However, it should be noted that, as disclosed in document 3 (Liu Qingling, Jiang Kuiming, A method for preparing spherical phosphor without ball milling, CN100554364C) and document 4 (Lei Lixu, Gao Xiaorui, Fluorescent material that converts ultraviolet light into red light and its preparation method, CN100489055C), the ball milling process can easily damage the crystal form of the luminescent material, reduce its luminescent performance, and result in uneven particle size distribution and the generation of many impurities or impurity phases. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems in the prior art and provide a method for obtaining nanoscale nitride fluorescent materials. The method specifically uses non-stoichiometric raw materials to prepare fluorescent materials and obtains a nanoscale nitride fluorescent material under relatively mild conditions without using a ball milling process that would damage the luminescence performance of the fluorescent material particles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for obtaining nanoscale nitride fluorescent materials includes the following steps:

[0008] 1) Ca mSi alloy, EuSi alloy and AlN powder are mixed uniformly in a molar ratio of (1-x):x:1 under a protective atmosphere. The uniformly mixed powder is then sintered at high temperature in an ammonia atmosphere to obtain an intermediate, wherein 1.2≤m≤1.4 and 0.02≤x≤0.08.

[0009] 2) Grind the intermediate obtained in step 1), mix the powder obtained after grinding with oxalic acid solution and sonicate to obtain a mixture containing precipitate;

[0010] 3) Filter and dry the mixture obtained in step 2) to obtain the nano-scale nitride fluorescent material.

[0011] The high-temperature sintering temperature is 1600–1800℃, and the high-temperature sintering time is 4–10 hours.

[0012] The aforementioned nanoscale nitride fluorescent material has the chemical formula Ca. x Eu 1-x AlSiN3, where 0.02≤x≤0.08.

[0013] Preferably, x can be 0.05 and m can be 1.32.

[0014] The median D50 particle size of the nanoscale nitride fluorescent material is 80 nm to 100 nm.

[0015] When excited by 450 nm light, the main peak of the emission spectrum of the nanoscale nitride fluorescent material is located at 670–710 nm, and the quantum efficiency is 50%–70%.

[0016] The aforementioned nanoscale nitride fluorescent material is used to prepare Mini LED devices.

[0017] The Mini LED device includes a Mini LED and the aforementioned nanoscale nitride fluorescent material; the Mini LED has an emission wavelength range of 380 nm to 480 nm and a planar size of 100 μm × 100 μm.

[0018] Compared with the prior art, the beneficial effects achieved by the technical solution of this invention are:

[0019] This invention provides a method for obtaining nanoscale nitride fluorescent materials. The chemical formula of the nanoscale nitride fluorescent material can be represented as: Ca x Eu 1-xAlSiN3, where 0.02≤x≤0.08; the median D50 particle size of this nanoscale nitride fluorescent material is 80 nm~100 nm; under 450 nm light excitation, the main peak position of the emission spectrum of this nanoscale nitride fluorescent material is 670 nm~710 nm, and the quantum efficiency is 50%~70%. In the preparation of this nanoscale nitride fluorescent material, non-stoichiometric raw materials were deliberately used. Under relatively mild synthesis conditions without ball milling processes that would damage the luminescence performance of the fluorescent material particles, a nanoscale nitride fluorescent material for Mini LED device packaging was finally obtained. Attached Figure Description

[0020] Figure 1 The emission spectrum of the sample obtained in Comparative Example 1 under 450 nm light excitation;

[0021] Figure 2 The emission spectrum of the sample obtained in Example 1 under 450 nm light excitation;

[0022] Figure 3 The image shows the SEM image of the sample obtained in Example 1.

[0023] Figure 4 This is a physical image of the sample obtained in Example 23 packaged as a Mini LED device. Detailed Implementation

[0024] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] This invention proposes a method for obtaining nanoscale nitride fluorescent materials, the chemical formula of which can be represented as: Ca x Eu 1-x AlSiN3, where 0.02≤x≤0.08; the median D50 particle size of this nanoscale nitride fluorescent material is between 80 nm and 100 nm; under excitation by 450 nm light, the main peak position of the emission spectrum of this nanoscale nitride fluorescent material is between 670 nm and 710 nm, and the quantum efficiency is between 50% and 70%.

[0026] To obtain the above-mentioned nanoscale nitride fluorescent material, the following steps were adopted:

[0027] Step (A): The chemical composition is Ca mSi alloys and alloys with the chemical composition EuSi and AlN powder are mixed uniformly in a protective atmosphere at a molar ratio of (1-x):x:1. The uniformly mixed powder is then sintered at high temperature in an ammonia atmosphere under a certain pressure to obtain an intermediate, wherein 1.2≤m≤1.4 and 0.02≤x≤0.08.

[0028] Step (B): Grind the intermediate obtained in step (A), mix the powder obtained after grinding with oxalic acid solution in a container, put the container into an ultrasonic cleaner for ultrasonic treatment, and obtain a solution containing precipitate.

[0029] Step (C): Filter the solution containing the precipitate obtained in step (B) using a filter membrane. After filtration, remove the residue from the filter membrane and dry it to obtain a final product with the chemical formula Ca. x Eu 1-x Nanoscale nitride fluorescent materials of AlSiN3 (where 0.02≤x≤0.08).

[0030] In step (A) above, Ca m The purity of Si alloy, EuSi alloy, and AlN powder is not less than 99.5%, where 1.2 ≤ m ≤ 1.4.

[0031] In step (A) above, the protective atmosphere is one or both of nitrogen or argon. In some embodiments provided by the present invention, the protective atmosphere is preferably nitrogen.

[0032] In step (A) above, the temperature of the high-temperature solid-phase reaction is between 1600 and 1800°C, the pressure of the ammonia atmosphere is 1 MPa, and the time of the high-temperature solid-phase reaction is between 4 and 10 hours.

[0033] In step (A) above, the temperature of the high-temperature solid phase is preferably 1600-1800°C, under an ammonia atmosphere pressure of 1 MPa; in some embodiments provided by the present invention, the temperature of the high-temperature solid phase is preferably 1700°C.

[0034] In step (A) above, the time for the high-temperature solid phase is preferably 4 to 10 hours, more preferably 5 to 8 hours; in some embodiments provided by the present invention, the time for the high-temperature solid phase is preferably 6 hours.

[0035] In step (A) above, the mixing process can be carried out in an environment familiar to those skilled in the art, and there are no special limitations; in this invention, a glove box is preferred. The sintering process can be carried out in an environment familiar to those skilled in the art, and there are no special limitations; in this invention, a high-temperature furnace is preferred. After the above sintering reaction is carried out, the mixture is cooled to room temperature in the furnace to obtain the intermediate.

[0036] In step (B) above, the mass ratio of powder to oxalic acid is 1:10, the concentration of oxalic acid is 0.5 mol / L, and the ultrasonic treatment time is 1 h.

[0037] In step (B) above, the ultrasonic treatment equipment can be any equipment known to those skilled in the art, and there are no special restrictions. In this invention, an ultrasonic cleaner is preferred, and the ultrasonic power is 50W.

[0038] In step (B) above, the pore size of the filter membrane is 50 nm, the drying temperature is 50℃, and the drying time is 3 h.

[0039] In Embodiment 1 of the present invention, m is preferably 1.32, and x is preferably 0.05; in Embodiments 2 to 8 of the present invention, m is preferably 1.2, and x is preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08; in Embodiments 9 to 15 of the present invention, m is preferably 1.3, and x is preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08; in further Embodiments 16 to 22 of the present invention, m is preferably 1.4, and x is preferably 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08.

[0040] The light-emitting device comprises a Mini LED and a fluorescence conversion material. The Mini LED emits light in the wavelength range of 380 nm to 480 nm and has a planar dimension of 100 μm × 100 μm. The fluorescence conversion material includes at least the material synthesized in the above steps, with the chemical formula Ca. x Eu 1-x Nanoscale nitride fluorescent materials of AlSiN3 (where 0.02≤x≤0.08).

[0041] All raw materials used in the following comparative examples and embodiments are commercially available.

[0042] Comparative Example 1

[0043] Make it according to the following steps:

[0044] CaSi alloy, EuSi alloy, and AlN were mixed uniformly in a nitrogen atmosphere at a ratio of 0.95:0.05:1. The uniformly mixed powder was then placed into a crucible, which was then placed in a high-temperature furnace and sintered at 1700℃ for 6 hours under an ammonia atmosphere at a pressure of 1 MPa. This yielded a compound with a theoretical chemical composition of Ca... 0.95 Eu 0.05 AlSiN3 material.

[0045] The luminescence properties of the material obtained in Comparative Example 1 were tested using a fluorescence spectrometer, and its emission spectrum is as follows: Figure 1 The results show that, under 450 nm light excitation, the main peak of the emission spectrum of the material obtained in Comparative Example 1 is located at 655 nm. The median D50 particle size of the obtained material was measured using a laser particle size analyzer. Due to the use of a conventional high-temperature solid-state reaction, the final median D50 particle size of the material was 12.445 μm. This value is obviously extremely large and completely unsuitable for packaging Mini LED devices. The sample was tested using a quantum efficiency meter. Since no destructive ball milling treatment was performed, the quantum efficiency of this sample under 450 nm light excitation was relatively high, at 71.7%. Specific data are shown in Table 1.

[0046] That is, without using raw materials with non-stoichiometric ratios and washing with oxalic acid, the material obtained in Comparative Example 1 is not a nanoscale nitride fluorescent material.

[0047] Comparative Example 2

[0048] Make it according to the following steps:

[0049] Step (A): CaSi alloy, EuSi alloy, and AlN were mixed uniformly in a nitrogen atmosphere at a ratio of 0.95:0.05:1. The uniformly mixed powder was then placed into a crucible, which was then placed in a high-temperature furnace and sintered at 1700℃ for 6 hours under an ammonia atmosphere at a pressure of 1 MPa. Finally, a powder with a theoretical chemical composition of Ca was obtained. 0.95 Eu 0.05 AlSiN3 material.

[0050] Step (B): Take a theoretical chemical composition obtained in step (A) that is Ca 0.95 Eu 0.05 50 grams of AlSiN3 material was placed in a 200 ml ball mill jar, along with 100 grams of agate grinding balls. The jar was then installed in a ball mill, and the milling speed was set to 600 rpm. The mill was started and milled for 4 hours. The milling process was then stopped. The material with the theoretical chemical composition Ca... 0.95 Eu 0.05 After the AlSiN3 material is removed from the ball mill jar, a ball-milled material with a theoretical chemical composition of Ca is obtained. 0.95 Eu 0.05 AlSiN3 material.

[0051] The luminescence performance of the material obtained in Comparative Example 2 was tested using a fluorescence spectrometer. Due to the ball milling process, the surface of the sample was damaged, resulting in numerous defects and a shift in the emission spectrum. Ultimately, under 450 nm light excitation, the main peak of the emission spectrum of the material obtained in Comparative Example 2 was located at 660 nm. The median D50 particle size of the material was measured using a laser particle size analyzer. Due to the prolonged ball milling process, the final median D50 particle size was 1.152 μm, indicating a significant decrease in the median particle size after ball milling. This median particle size is generally acceptable for Mini LED device packaging. However, the quantum efficiency test showed that due to the destructive ball milling process, the quantum efficiency of the sample was low at 35.1% under 450 nm light excitation. This means that the luminous efficiency of the Mini LED device packaged with the material obtained in Comparative Example 2 will be poor. Specific data are shown in Table 1.

[0052] That is, the material obtained in Comparative Example 2 is not a nanoscale nitride fluorescent material.

[0053] Comparative Example 3

[0054] Make it according to the following steps:

[0055] Step (A): The chemical composition is Ca 1.15 Si alloys, EuSi alloys, and AlN powder were mixed uniformly in a nitrogen atmosphere at a molar ratio of 0.95:0.05:1. The uniformly mixed powder was then placed into a crucible, which was then placed into a high-temperature furnace and sintered at 1700°C for 6 hours in an ammonia atmosphere at a pressure of 1 MPa to obtain an intermediate.

[0056] Step (B): Grind the intermediate obtained in step (A), mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10, and then put the container into an ultrasonic cleaner with a power of 50W for ultrasonic treatment for 1 hour to finally obtain a solution containing precipitate.

[0057] Step (C): The solution containing the precipitate obtained in step (B) is filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven for drying at 50°C for 3 hours, finally yielding a solid powder material.

[0058] Compared with Comparative Example 1, the chemical component selected for Comparative Example 3 is Ca. 1.15 The alloy used in Comparative Example 3 is a Si alloy, not a CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 3 are not stoichiometric. Theoretically, Ca...1.15 In a high-temperature furnace, Si reacts with ammonia to produce Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately produce Ca. 0.95 Eu 0.05 AlSiN3. However, due to Ca... 1.15 The Si alloy contains excess Ca, meaning that during the reaction with ammonia, excess Ca3N2 is produced. This excess Ca3N2 inhibits the solid-state reaction, preventing the solid particles obtained from the high-temperature solid-state reaction from growing to a large size; the median D50 particle size is even only in the nanometer range. The excess Ca3N2 decomposes after washing with oxalic acid, and after filtration and drying, the final solid powder contains only fluorescent material (due to the inability of the solid particles to grow to a large size).

[0059] The median D50 particle size of the material obtained in Comparative Example 3 was measured using a laser particle size analyzer, and the median particle size was 933 nm. Clearly, the above steps can indeed yield a nanoscale nitride phosphor, and this median particle size is suitable for Mini LED device packaging. The luminescence performance of the material obtained in Comparative Example 3 was tested using a fluorescence spectrometer. Due to the absence of ball milling, the micro-nano scale characteristics of the sample altered its energy level band gap, resulting in a main peak in the emission spectrum at 661 nm under 450 nm light excitation. The quantum efficiency of the sample was tested using a quantum efficiency meter, and the results showed that, due to the absence of destructive ball milling, the sample exhibited a high quantum efficiency of 55.2% under 450 nm light excitation. Specific data are shown in Table 1.

[0060] That is, the material obtained in Comparative Example 3 is a nanoscale nitride fluorescent material, but the median particle size is relatively high.

[0061] Comparative Example 4

[0062] Make it according to the following steps:

[0063] Step (A): The chemical composition is Ca 1.45 Si alloys, EuSi alloys, and AlN powder were mixed uniformly in a nitrogen atmosphere at a molar ratio of 0.95:0.05:1. The uniformly mixed powder was then placed into a crucible, which was then placed into a high-temperature furnace and sintered at 1700°C for 6 hours in an ammonia atmosphere at a pressure of 1 MPa to obtain an intermediate.

[0064] Step (B): Grind the intermediate obtained in step (A), mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10, and then put the container into an ultrasonic cleaner with a power of 50W for ultrasonic treatment for 1 hour to finally obtain a solution containing precipitate.

[0065] Step (C): The solution containing the precipitate obtained in step (B) is filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven for drying at 50°C for 3 hours, finally yielding a solid powder material.

[0066] Compared with Comparative Example 1, the chemical component selected for Comparative Example 4 is Ca. 1.45 The alloy used in Comparative Example 4 is a Si alloy, not a CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 4 are not stoichiometric. Theoretically, Ca... 1.45 In a high-temperature furnace, Si reacts with ammonia to produce Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately produce Ca. 0.95 Eu 0.05 AlSiN3. However, due to Ca... 1.45 The Si alloy contains a greater excess of Ca (compared to Comparative Example 3), meaning that during the reaction with ammonia, a greater excess of Ca3N2 is produced. This excess Ca3N2 inhibits the solid-state reaction, preventing the solid particles obtained in the high-temperature solid-state reaction from growing to a larger size; the median D50 particle size is even only in the nanometer range. The excess Ca3N2 decomposes after washing with oxalic acid, and after filtration and drying, the final solid powder contains only fluorescent material (due to the inability of the solid particles to grow to a large size).

[0067] The median D50 particle size of the material obtained in Comparative Example 4 was measured using a laser particle size analyzer, and the median particle size was 57 nm. Clearly, the above steps can indeed yield a nanoscale nitride phosphor, and this median particle size is suitable for Mini LED device packaging. The luminescence performance of the material obtained in Comparative Example 4 was tested using a fluorescence spectrometer. Due to the absence of ball milling, the micro-nano scale characteristics of the sample altered its energy level band gap, resulting in a main peak in the emission spectrum at 711 nm under 450 nm light excitation. The quantum efficiency of the sample was tested using a quantum efficiency meter, and the results showed that, due to the absence of destructive ball milling, the sample exhibited a high quantum efficiency of 57.3% under 450 nm light excitation. Specific data are shown in Table 1.

[0068] That is, the material obtained in Comparative Example 4 is a nanoscale nitride fluorescent material. However, the median particle size of the material obtained in Comparative Example 4 is too small, resulting in a low bulk density of the sample, making storage inconvenient.

[0069] Comparative Example 5

[0070] Step (A): The alloy with chemical composition CaSi, the alloy with chemical composition EuSi, and AlN powder are mixed evenly under nitrogen atmosphere in a molar ratio of 0.95:0.05:1. The evenly mixed powder is then placed into a crucible, which is then placed into a high-temperature furnace and sintered at 1700℃ for 6 hours under an ammonia atmosphere at a pressure of 1MPa to obtain an intermediate.

[0071] Step (B): Grind the intermediate obtained in step (A), mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10, and then put the container into an ultrasonic cleaner with a power of 50W for ultrasonic treatment for 1 hour to finally obtain a solution containing precipitate.

[0072] Step (C): The solution containing the precipitate obtained in step (B) is filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven for drying at 50°C for 3 hours, finally yielding a solid powder material.

[0073] Comparative Example 5 uses an alloy with the chemical composition CaSi, and therefore does not have the non-stoichiometric ratio problem of Comparative Example 3 / 4. However, Comparative Example 5 uses an oxalic acid washing process, which will obviously remove the tiny particles present in the obtained material, theoretically leading to an increase in the median particle size of the sample.

[0074] The median D50 particle size of the material obtained in Comparative Example 5 was measured using a laser particle size analyzer, and the median particle size was 16.701 μm. The median particle size of this phosphor does not meet the requirements for Mini LED device packaging. The luminescence performance of the material obtained in Comparative Example 5 was tested using a fluorescence spectrometer. Since it was not ball-milled, the main peak of the emission spectrum was located at 656 nm under 450 nm light excitation. The quantum efficiency of this sample was tested using a quantum efficiency meter. The results show that, due to the lack of destructive ball-milling, the quantum efficiency of this sample under 450 nm light excitation is relatively high, at 76.3%. Specific data are shown in Table 1.

[0075] That is, the material obtained in Comparative Example 5 is not a nanoscale nitride fluorescent material.

[0076] Example 1

[0077] Make it according to the following steps:

[0078] Step (A): The chemical composition is Ca 1.32 Si alloys, EuSi alloys, and AlN powder were mixed uniformly in a nitrogen atmosphere at a molar ratio of 0.95:0.05:1. The uniformly mixed powder was then placed into a crucible, which was then placed into a high-temperature furnace and sintered at 1700°C for 6 hours in an ammonia atmosphere at a pressure of 1 MPa to obtain an intermediate.

[0079] Step (B): Grind the intermediate obtained in step (A), mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10, and then put the container into an ultrasonic cleaner with a power of 50W for ultrasonic treatment for 1 hour to finally obtain a solution containing precipitate.

[0080] Step (C): The solution containing the precipitate obtained in step (B) is filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven for drying at 50°C for 3 hours, finally yielding a solid powder material.

[0081] Compared with Comparative Example 1, the chemical component selected in Example 1 was Ca. 1.32 The alloy used is Si, not the CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 1 are not stoichiometric. Theoretically, Ca... 1.32 In a high-temperature furnace, Si reacts with ammonia to produce Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately produce Ca. 0.95 Eu 0.05 AlSiN3. Due to Ca 1.32 The amount of Ca in the Si alloy is suitable (compared to 3 / 4 of the comparative example), meaning that during the reaction with ammonia, a suitable amount of Ca3N2 will be produced. This suitable amount of Ca3N2 will inhibit the solid-state reaction, but the degree of inhibition is appropriate. Ultimately, the solid particles obtained in the high-temperature solid-state reaction meet the packaging requirements of Mini LED devices, and the quantum efficiency and the main peak position of the emission spectrum are suitable. Furthermore, the excess Ca3N2 is decomposed after washing with oxalic acid, and after filtration and drying, only fluorescent material with a suitable median particle size remains in the final solid powder.

[0082] The luminescence properties of the material obtained in Example 1 were tested using a fluorescence spectrometer, and the results are as follows: Figure 2 As shown, the micro-nano particle size characteristics of the sample lead to a change in its (structure's) energy level band gap, with the main peak of the emission spectrum located at 690 nm under 450 nm photoexcitation. Figure 3The SEM image of the sample shows that the particle size is relatively small. The D50 median particle size of the material obtained in Example 1 was measured using a laser particle size analyzer, and the median particle size was 90 nm.

[0083] Both Example 1 and Comparative Example 5 employed an oxalic acid washing process. The difference lies in the proportions: Comparative Example 5 used stoichiometric CaSi alloy raw materials, while Example 1 used non-stoichiometric Ca... 1.32 The Si alloy raw material resulted in a significant difference in the median D50 particle size between the two materials. The median D50 particle size of the material obtained in Comparative Example 5 was 16.701 μm, while that of Example 1 was 90 nm. The reason for this is as described above: Comparative Example 5 used a stoichiometric CaSi alloy raw material, and during the high-temperature sintering process, all the raw materials reacted, ultimately producing a single product (fluorescent material); while Example 1 used a non-stoichiometric CaSi alloy raw material. 1.32 Si alloy raw materials, Ca 1.32 In the Si alloy, excess Ca reacts with ammonia to generate (excess Ca3N2 that cannot participate in further reaction). This excess Ca3N2 surrounds the newly generated fluorescent material particles, preventing them from growing further. In other words, the excess Ca3N2 acts as a barrier layer, preventing further high-temperature solid-state reactions. Ultimately, this results in a significant difference in the median D50 particle size of the fluorescent material obtained in Example 1 compared to that in Comparative Example 5.

[0084] Clearly, by following the above steps, a nanoscale nitride phosphor can be obtained, whose median particle size meets the requirements for Mini LED device packaging. Tests using a quantum efficiency meter show that, due to the absence of destructive ball milling, the sample exhibits a high quantum efficiency of 69.9% under 450 nm light excitation. Specific data are shown in Table 1.

[0085] That is, the material obtained in Example 1 is a nanoscale nitride fluorescent material with a D50 median particle size of 80 nm to 100 nm, an emission spectrum with a main peak position of 670 nm to 710 nm under 450 nm light excitation, and a quantum efficiency of 50% to 70%.

[0086] Examples 2-8

[0087] Make it according to the following steps:

[0088] Step (A): The chemical composition is Ca 1.2Si alloys, EuSi alloys, and AlN powder were mixed uniformly under a nitrogen atmosphere at molar ratios of 0.98:0.02:1 (Example 2), 0.97:0.03:1 (Example 3), 0.96:0.04:1 (Example 4), 0.95:0.05:1 (Example 5), 0.94:0.06:1 (Example 6), 0.93:0.07:1 (Example 7), and 0.92:0.08:1 (Example 8). The uniformly mixed powders were then placed into crucibles, which were then placed in a high-temperature furnace and sintered at 1700°C for 6 hours under an ammonia atmosphere at a pressure of 1 MPa to obtain different intermediates.

[0089] Step (B): Grind the different intermediates obtained in step (A), and mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10. Then, place the container in an ultrasonic cleaner with a power of 50W and ultrasonically treat it for 1 hour. Finally, solutions containing precipitates are obtained.

[0090] Step (C): The different solutions containing precipitates obtained in step (B) are filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven to dry at 50°C for 3 hours, finally obtaining different solid powder materials.

[0091] Compared with Comparative Example 1, the chemical component selected in Examples 2-8 was Ca. 1.2 The alloy used is Si, not the CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 1 are not stoichiometric. Theoretically, Ca... 1.2 In a high-temperature furnace, Si reacts with ammonia to form Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately yield Eu-doped CaAlSiN3. Because Ca... 1.2 The amount of Ca in the Si alloy is suitable (compared to 3 / 4 of the comparative example), meaning that during the reaction with ammonia, a suitable amount of Ca3N2 will be produced. This suitable amount of Ca3N2 will inhibit the solid-state reaction, but the degree of inhibition is appropriate. Ultimately, the solid particles obtained in the high-temperature solid-state reaction meet the packaging requirements of Mini LED devices, and the quantum efficiency and the main peak position of the emission spectrum are suitable. Furthermore, the excess Ca3N2 is decomposed after washing with oxalic acid, and after filtration and drying, only fluorescent material with a suitable median particle size remains in the final solid powder.

[0092] The luminescence properties of the materials obtained in Examples 2–8 were tested using a fluorescence spectroscopy instrument. The micro-nano particle size characteristics of the samples caused changes in their (structural) band gaps. Under 450 nm light excitation, the main peaks of the emission spectra were located at 670 nm (Example 2), 675 nm (Example 3), 681 nm (Example 4), 685 nm (Example 5), 690 nm (Example 6), 698 nm (Example 7), and 702 nm (Example 8), respectively. The median D50 particle size of the materials obtained in Examples 2–8 was measured using a laser particle size analyzer. The median particle size values ​​were 99 nm (Example 2), 96 nm (Example 3), 97 nm (Example 4), 93 nm (Example 5), 96 nm (Example 6), 92 nm (Example 7), and 90 nm (Example 8), respectively. Obviously, by adopting the above steps, a nano-sized nitride phosphor can be obtained, and the median particle size of this phosphor can meet the packaging requirements of Mini LED devices. The results of testing samples 2-8 using a quantum efficiency meter show that, due to the absence of destructive ball milling, these samples exhibit high quantum efficiencies under 450nm light excitation: 50.3% (Example 2), 57.2% (Example 3), 59.9% (Example 4), 67.1% (Example 5), 66.8% (Example 6), 54.2% (Example 7), and 51.1% (Example 8), respectively. Specific data are shown in Table 1.

[0093] That is, the materials obtained in Examples 2 to 8 are nanoscale nitride fluorescent materials with a D50 median particle size of 80 nm to 100 nm, an emission spectrum with a main peak position of 670 nm to 710 nm under 450 nm light excitation, and a quantum efficiency of 50% to 70%, which can meet the packaging requirements of Mini LED.

[0094] Examples 9-15

[0095] Make it according to the following steps:

[0096] Step (A): The chemical composition is Ca 1.3Si alloys and EuSi alloys with AlN powder were mixed uniformly under a nitrogen atmosphere at molar ratios of 0.98:0.02:1 (Example 9), 0.97:0.03:1 (Example 10), 0.96:0.04:1 (Example 11), 0.95:0.05:1 (Example 12), 0.94:0.06:1 (Example 13), 0.93:0.07:1 (Example 14), and 0.92:0.08:1 (Example 15). The uniformly mixed powders were then placed into crucibles, which were then placed in a high-temperature furnace and sintered at 1700°C for 6 hours under an ammonia atmosphere at a pressure of 1 MPa to obtain different intermediates.

[0097] Step (B): Grind the different intermediates obtained in step (A), and mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10. Then, place the container in an ultrasonic cleaner with a power of 50W and ultrasonically treat it for 1 hour. Finally, solutions containing precipitates are obtained.

[0098] Step (C): The different solutions containing precipitates obtained in step (B) are filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven to dry at 50°C for 3 hours, finally obtaining different solid powder materials.

[0099] Compared with Comparative Example 1, the chemical component selected in Examples 9-15 was Ca. 1.3 The alloy used is Si, not the CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 1 are not stoichiometric. Theoretically, Ca... 1.3 In a high-temperature furnace, Si reacts with ammonia to form Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately yield Eu-doped CaAlSiN3. Because Ca... 1.3 The amount of Ca in the Si alloy is suitable (compared to 3 / 4 of the comparative example), meaning that during the reaction with ammonia, a suitable amount of Ca3N2 will be produced. This suitable amount of Ca3N2 will inhibit the solid-state reaction, but the degree of inhibition is appropriate. Ultimately, the solid particles obtained in the high-temperature solid-state reaction meet the packaging requirements of Mini LED devices, and the quantum efficiency and the main peak position of the emission spectrum are suitable. Furthermore, the excess Ca3N2 is decomposed after washing with oxalic acid, and after filtration and drying, only fluorescent material with a suitable median particle size remains in the final solid powder.

[0100] The luminescence properties of the materials obtained in Examples 9–15 were tested using a fluorescence spectroscopy instrument. The micro-nano particle size characteristics of the samples resulted in changes in their (structural) band gaps. Under 450 nm light excitation, the main peaks of the emission spectra were located at 671 nm (Example 9), 678 nm (Example 10), 685 nm (Example 11), 690 nm (Example 12), 695 nm (Example 13), 703 nm (Example 14), and 707 nm (Example 15), respectively. The median D50 particle size of the materials obtained in Examples 9–15 was measured using a laser particle size analyzer. The median particle size values ​​were 88 nm (Example 9), 87 nm (Example 10), 86 nm (Example 11), 91 nm (Example 12), 92 nm (Example 13), 86 nm (Example 14), and 88 nm (Example 15), respectively. Clearly, by using the above steps, a nano-sized nitride phosphor can be obtained, and the median particle size of this phosphor meets the requirements for Mini LED device packaging. The results of testing samples 9-15 using a quantum efficiency meter show that, due to the absence of destructive ball milling, these samples exhibit high quantum efficiencies under 450 nm light excitation: 54.4% (Example 9), 56.7% (Example 10), 59.2% (Example 11), 68.2% (Example 12), 60.3% (Example 13), 61.5% (Example 14), and 66.6% (Example 15), respectively. Specific data are shown in Table 1.

[0101] That is, the materials obtained in Examples 9 to 15 are nanoscale nitride fluorescent materials with a D50 median particle size of 80 nm to 100 nm, an emission spectrum with a main peak position of 670 nm to 710 nm under 450 nm light excitation, and a quantum efficiency of 50% to 70%, which can meet the packaging requirements of Mini LED.

[0102] Examples 16-22

[0103] Make it according to the following steps:

[0104] Step (A): The chemical composition is Ca 1.4Si alloys and EuSi alloys with chemical composition and AlN powder were mixed uniformly under a nitrogen atmosphere at molar ratios of 0.98:0.02:1 (Example 16), 0.97:0.03:1 (Example 17), 0.96:0.04:1 (Example 18), 0.95:0.05:1 (Example 19), 0.94:0.06:1 (Example 20), 0.93:0.07:1 (Example 21), and 0.92:0.08:1 (Example 22). The uniformly mixed powders were then placed into crucibles, which were then placed in a high-temperature furnace and sintered at 1700°C for 6 hours under an ammonia atmosphere at a pressure of 1 MPa to obtain different intermediates.

[0105] Step (B): Grind the different intermediates obtained in step (A), and mix the powder obtained after grinding with a 0.5 mol / L oxalic acid solution in a container at a mass ratio of 1:10. Then, place the container in an ultrasonic cleaner with a power of 50W and ultrasonically treat it for 1 hour. Finally, solutions containing precipitates are obtained.

[0106] Step (C): The different solutions containing precipitates obtained in step (B) are filtered through a filter membrane with a pore size of 50 nm. After filtration, the residue on the filter membrane is removed and placed in an oven to dry at 50°C for 3 hours, finally obtaining different solid powder materials.

[0107] Compared with Comparative Example 1, the chemical component selected in Examples 16-22 was Ca. 1.4 The alloy used is Si, not the CaSi alloy used in Comparative Example 1. This means that the raw materials used in Comparative Example 1 are not stoichiometric. Theoretically, Ca... 1.3 In a high-temperature furnace, Si reacts with ammonia to form Ca3N2 and Si3N4. Ca3N2 and Si3N4 then react with EuN (the product of the reaction of EuSi and ammonia) and AlN to ultimately yield Eu-doped CaAlSiN3. Because Ca... 1.4 The amount of Ca in the Si alloy is suitable (compared to 3 / 4 of the comparative example), meaning that during the reaction with ammonia, a suitable amount of Ca3N2 will be produced. This suitable amount of Ca3N2 will inhibit the solid-state reaction, but the degree of inhibition is appropriate. Ultimately, the solid particles obtained in the high-temperature solid-state reaction meet the packaging requirements of Mini LED devices, and the quantum efficiency and the main peak position of the emission spectrum are suitable. Furthermore, the excess Ca3N2 is decomposed after washing with oxalic acid, and after filtration and drying, only fluorescent material with a suitable median particle size remains in the final solid powder.

[0108] The luminescence properties of the materials obtained in Examples 16–22 were tested using a fluorescence spectroscopy instrument. The micro-nano particle size characteristics of the samples resulted in changes in their (structural) band gaps. Under 450 nm light excitation, the main peaks of the emission spectra were located at 673 nm (Example 16), 682 nm (Example 17), 685 nm (Example 18), 693 nm (Example 19), 699 nm (Example 20), 705 nm (Example 21), and 710 nm (Example 22), respectively. The median D50 particle size of the materials obtained in Examples 16–22 was measured using a laser particle size analyzer. The median particle size values ​​were 86 nm (Example 16), 86 nm (Example 17), 82 nm (Example 18), 81 nm (Example 19), 86 nm (Example 20), 85 nm (Example 21), and 90 nm (Example 22), respectively. Clearly, by using the above steps, a nano-sized nitride phosphor can be obtained, and the median particle size of this phosphor meets the requirements for MiniLED device packaging. The results of testing samples 16–22 using a quantum efficiency meter show that, due to the absence of destructive ball milling, these samples exhibit high quantum efficiencies under 450 nm light excitation: 59.1% (Example 16), 59.4% (Example 17), 63.4% (Example 18), 66.7% (Example 19), 67.2% (Example 20), 50.9% (Example 21), and 50.4% (Example 22), respectively. Specific data are shown in Table 1.

[0109] That is, the materials obtained in Examples 16 to 22 are nanoscale nitride fluorescent materials with a D50 median particle size of 80 nm to 100 nm, an emission spectrum with a main peak position of 670 nm to 710 nm under 450 nm light excitation, and a quantum efficiency of 50% to 70%, which can meet the packaging requirements of Mini LED.

[0110] Example 23

[0111] The chemical formula obtained in Example 1 is Ca 0.95 Eu 0.05 AlSiN3 nanoscale nitride fluorescent material is encapsulated with a Mini LED with an emission wavelength of 450 nm and a planar size of 100 μm × 100 μm. The specific encapsulation process involves: encapsulating AlSiN3 nanoscale nitride fluorescent material with a chemical formula of Ca... 0.95 Eu 0.05 AlSiN3 nano-scale nitride fluorescent material is mixed with epoxy resin at a mass ratio of 1:3.75, then coated onto the surface of a Mini LED with an emission wavelength of 450 nm and a planar size of 100 μm × 100 μm, and then cured at 150°C for 30 minutes to obtain a Mini LED device. Figure 4 A physical diagram of the device obtained in Example 23 is provided.

[0112] Table 1. Data on material properties corresponding to comparative examples and embodiments.

[0113]

[0114] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for obtaining nanoscale nitride fluorescent materials, characterized in that, Includes the following steps: 1) Ca m Si alloy, EuSi alloy and AlN powder are mixed uniformly in a molar ratio of (1-x):x:1 under a protective atmosphere. The uniformly mixed powder is then sintered at high temperature in an ammonia atmosphere to obtain an intermediate, wherein 1.2≤m≤1.4 and 0.02≤x≤0.

08. 2) Grind the intermediate obtained in step 1), mix the powder obtained after grinding with oxalic acid solution and sonicate to obtain a mixture containing precipitate; 3) Filter and dry the mixture obtained in step 2) to obtain the nano-scale nitride fluorescent material.

2. The method for obtaining nanoscale nitride fluorescent materials as described in claim 1, characterized in that: The high-temperature sintering temperature is 1600–1800℃, and the high-temperature sintering time is 4–10 hours.

3. A nanoscale nitride fluorescent material, characterized in that: Prepared by the method described in any one of claims 1 to 2.

4. The nanoscale nitride fluorescent material as described in claim 3, characterized in that: The chemical formula is Ca 1- x Eu x AlSiN3, where 0.02≤x≤0.

08.

5. A nanoscale nitride fluorescent material as described in claim 3, characterized in that: The median D50 particle size of the nanoscale nitride fluorescent material is 80 nm to 100 nm.

6. A nanoscale nitride fluorescent material as described in claim 3, characterized in that: When excited by 450 nm light, the main peak of the emission spectrum of the nanoscale nitride fluorescent material is located at 670–710 nm, and the quantum efficiency is 50%–70%.

7. The application of the nanoscale nitride fluorescent material according to claim 3, characterized in that: Used to fabricate Mini LED devices.

8. A Mini LED device, characterized in that: It includes Mini LEDs and the nanoscale nitride fluorescent material as described in claim 3.

9. A Mini LED device as described in claim 8, characterized in that: The Mini LED emits wavelengths in the range of 380 nm to 480 nm.

10. A Mini LED device as described in claim 8, characterized in that: The Mini LED has a planar dimension of 100 μm × 100 μm.

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