Fluorescence-conversion red phosphor for display, preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of light-emitting display materials, and provides a fluorescence-conversion red phosphor for display, a preparation method therefor and a use thereof. In the present invention, metal Sr, metal Al, and metal Eu are mixed and melted according to a stoichiometric ratio, and then ground to obtain alloy powder. Lithium aluminum hydride powder and the alloy powder are ground and mixed, calcined and ground again to obtain a red phosphor for laser display having high brightness under blue light excitation. In the present invention, an alloying method is used in combination with a nitridation method. In the prepared phosphor product, the molar proportion (greater than 70%) of Eu2+ (radiative transition) among all Eu elements is significantly increased. Therefore, the prepared red phosphor has high color purity, and high luminous efficiency and thermal stability; and the phosphor sample has an ultra-high saturation threshold under blue laser excitation, can be applied to fluorescence-conversion laser display technology, and has great potential for use in laser display devices.

Description

A fluorescence-converting red phosphor for display, its preparation method and application Technical Field

[0001] This invention relates to the field of light-emitting display materials technology, and in particular to a fluorescence-converting red phosphor for display, its preparation method, and its application. Background Technology

[0002] Fluorescence-conversion laser display technology uses blue laser as the primary light source and achieves the emission of red, green, and blue primary colors through fluorescence conversion materials. It boasts advantages such as large size, high definition, and high brightness, and has become one of the mainstream international laser display technologies, with wide applications in home displays, laser cinemas, and engineering projection. This technology primarily uses blue lasers to remotely excite luminescent materials; therefore, the luminescent material is one of the core components of laser fluorescence display technology. With the increasing demand for ultra-high color gamut fluorescence-conversion laser displays, higher requirements are being placed on the performance of red and green rare-earth luminescent materials.

[0003] To promote the development of fluorescence conversion laser display technology, high-purity, high-efficiency, and mass-producible phosphors are urgently needed. 3+ While doped green high-efficiency phosphor systems have been extensively studied, research on red-emitting phosphor systems is more challenging and significant. Nitride red phosphors exhibit higher stability and spectral characteristics compared to other phosphor systems. Among them, (Sr,Ca)AlSiN3:Eu 2+ and (Sr,Ca,Ba)2Si5N8:Eu 2+ Due to their high luminous efficiency, LEDs have been used in commercial displays; however, their inherent broadband emission limits their use in laser display devices. SrLiAl3N4:Eu 2+ Red phosphors, due to the high symmetry and rigidity of the channel structure formed by LiN4 and AlN4 tetrahedra, exhibit narrow-band emission characteristics, meeting the requirements of laser display applications. However, the preparation of high-quantum-efficiency SLAN red phosphors faces challenges such as expensive raw materials (SrH (strontium hydride)) and demanding synthesis conditions. Using common nitrides as raw materials generally yields SLAN phosphors with lower quantum efficiencies. Therefore, developing a simple and economical strategy for synthesizing high-quantum-efficiency SLAN red phosphors is of great significance for promoting their commercial application and advancing fluorescence-conversion laser display technology. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorescence-converting red phosphor for display, its preparation method and application. The method is simple and economical, and the prepared red phosphor has high color purity, high luminous efficiency and thermal stability, while having an ultra-high saturation threshold under blue laser excitation.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a fluorescence-converting red phosphor for display, comprising the following steps;

[0007] The chemical formula of the fluorescence-converting red phosphor used in the display is: Sr (1-x) Eu x LiAl3N4, where 0.001≤x≤0.007;

[0008] According to the chemical formula Sr (1-x) Eu x The required stoichiometric ratio for LiAl3N4 is obtained by mixing metallic Sr, metallic Al, and metallic Eu, followed by vacuum melting under a protective atmosphere, and then crushing and grinding to obtain alloy powder.

[0009] According to the chemical formula Sr (1-x) Eu x The required stoichiometric ratio of Li element in LiAl3N4 is determined by grinding and mixing lithium aluminum hydride with the alloy powder, and then sintering the resulting mixed powder under gas pressure in a nitrogen atmosphere to obtain a fluorescent conversion type red phosphor for display.

[0010] The total amount of Al in the metallic Al and lithium aluminum hydride reaches the chemical formula Sr (1-x) Eu x The required stoichiometric ratio of Al in LiAl3N4.

[0011] Preferably, the protective gas used in the protective atmosphere includes argon.

[0012] Preferably, the vacuum melting conditions include: a temperature of 1500–1800°C, an ignition time of 10–20 seconds per ignition, and a vacuum degree of <5 × 10⁻⁶. -3 Pa.

[0013] Preferably, the theoretical mass is the mass of lithium aluminum hydride corresponding to the required stoichiometric ratio of Li, and the actual added mass of lithium aluminum hydride is 20-40% of the theoretical mass.

[0014] Preferably, the gas pressure sintering temperature is 1050–1100°C and the time is 4–6 hours.

[0015] Preferably, the nitrogen pressure during the gas pressure sintering is 0.4 to 0.6 MPa.

[0016] The present invention provides a display fluorescent conversion type red phosphor prepared by the preparation method described in the above technical solution.

[0017] Preferably, the display fluorescent conversion type red phosphor contains Eu. 2+ The molar percentage of total Eu is >70%.

[0018] Preferably, blue light with a wavelength of 450-500 nm is used as the excitation source for irradiation, and the display fluorescent conversion type red phosphor exhibits luminescence characteristics with an emission spectrum peak of 652 nm and a half-width of 52 nm.

[0019] This invention provides the application of the fluorescence-converting red phosphor for display described in the above technical solution in the field of laser display.

[0020] This invention provides a method for preparing a fluorescence-converting red phosphor for displays. Metals Sr, Al, and Eu are mixed and smelted according to a stoichiometric ratio, and then ground to obtain an alloy powder. Lithium aluminum hydride powder is then ground and mixed with the alloy powder, calcined, and ground again to obtain a red phosphor for laser displays with high brightness under blue light excitation. This invention employs an alloying method combined with a nitriding method. During the nitriding process, due to the presence of the alloy precursor, Eu… 2+ (Radiative transition) Oxidation to Eu 3+ The process of (non-radiative transition) is greatly reduced, Eu 2+ As a radiative transition center, an increase in its proportion is beneficial for emission enhancement. And the generation of Eu... 3+ This will force the formation of Li + The use of vacancies to maintain charge balance leads to an increase in the local lattice volume, disrupting the original symmetry and resulting in an increase in internal defects and nonradiative transitions. Therefore, the method of this invention can reduce Eu... 3+ The formation of Eu in the prepared phosphor product 2+ The significantly increased molar percentage (greater than 70%) of Eu in the total elemental composition is beneficial for reducing internal defects formed by doping. This is particularly relevant in the radiative transition state of Eu. 2+ With the combined effect of defect reduction, red phosphors with high color purity, high luminous efficiency and thermal stability can be obtained. At the same time, they have an ultra-high saturation threshold under blue laser excitation, which can be applied to fluorescence conversion laser display technology and has great potential for use in laser display devices.

[0021] The red phosphor prepared by this invention has high brightness, with an external quantum efficiency of 52.38% at room temperature; it also has high color purity, at 21 W / mm². 2 Under power density laser excitation, its CIE-X value is 0.7026; it has a high laser saturation threshold, reaching 72.64 W / mm² under different power density laser excitations. 2 .

[0022] This invention uses an alloying method combined with a nitriding method to prepare a high-brightness red phosphor, which is a high-purity phase product with good stability and high color purity. The method is efficient and can be scaled up. Attached Figure Description

[0023] Figure 1 shows the powder X-ray diffraction patterns of the red phosphors prepared in Examples 1-4;

[0024] Figure 2 shows the excitation spectrum of the red phosphor prepared in Example 2;

[0025] Figure 3 shows the emission spectrum of the red phosphor prepared in Example 2;

[0026] Figure 4 shows the scanning electron microscope (SEM) image (a) and particle size distribution (b) of the red phosphor prepared in Example 1;

[0027] Figure 5 shows the quantum efficiency spectrum of the red phosphor prepared in Example 1;

[0028] Figure 6 shows the quantum efficiency spectrum of the red phosphor prepared in Comparative Example 1;

[0029] Figure 7 shows the X-ray near-edge absorption spectrum of the red phosphor prepared in Example 1;

[0030] Figure 8 shows the curves (a) and emission spectra (b) of the light flux of the red phosphor prepared in Example 1 as a function of increasing incident laser power density under different laser power excitation.

[0031] Figure 9 shows the emission spectra of the red phosphor prepared in Example 1 at different temperatures. Detailed Implementation

[0032] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0033] This invention provides a method for preparing a fluorescence-converting red phosphor for display, comprising the following steps;

[0034] The chemical formula of the fluorescence-converting red phosphor used in the display is: Sr (1-x) Eu x LiAl3N4, where 0.001≤x≤0.007;

[0035] According to the chemical formula Sr (1-x) Eu x The required stoichiometric ratio for LiAl3N4 is obtained by mixing metallic Sr, metallic Al, and metallic Eu, followed by vacuum melting under a protective atmosphere, and then crushing and grinding to obtain alloy powder.

[0036] According to the chemical formula Sr (1-x) Eu xThe required stoichiometric ratio of Li element in LiAl3N4 is determined by grinding and mixing lithium aluminum hydride with the alloy powder, and then sintering the resulting mixed powder under gas pressure in a nitrogen atmosphere to obtain a fluorescent conversion type red phosphor for display.

[0037] The total amount of Al in the metallic Al and lithium aluminum hydride reaches the chemical formula Sr (1-x) Eu x The required stoichiometric ratio of Al in LiAl3N4.

[0038] In this invention, the chemical formula of the fluorescence-converting red phosphor for display is: Sr (1-x) Eu x LiAl3N4, wherein 0.001≤x≤0.007, and x is preferably 0.003~0.005.

[0039] The present invention does not have any special limitation on the source of the metals Sr, Al and Eu, and any commercially available products well known in the art are acceptable.

[0040] In this invention, the protective gas used in the protective atmosphere preferably includes argon.

[0041] In this invention, the preferred conditions for vacuum melting include: a temperature of 1500–1800°C, an ignition time of 10–20 seconds per ignition, and a vacuum degree of <5 × 10⁻⁶. -3 Pa.

[0042] This invention preferably involves weighing blocky Sr, blocky Al, and blocky Eu metals in a glove box, sealing all the blocky metals in a sealed bag, transferring them from the glove box to a vacuum arc melting furnace for melting, turning them 2-3 times, and then allowing them to cool naturally to room temperature to obtain a silvery-white metal alloy block. The metal alloy block is then transferred back to the glove box in a sealed bag, crushed, and ground to obtain alloy powder. This invention does not have a specific limitation on the particle size of the alloy powder; it can be adjusted according to actual needs.

[0043] In this invention, the theoretical mass of lithium aluminum hydride corresponding to the required stoichiometric ratio of Li is used, and the actual added mass of lithium aluminum hydride is 20-40% of the theoretical mass. That is, this invention is based on the chemical formula Sr... (1-x) Eu x The stoichiometric ratio of lithium in LiAl3N4 (0.001≤x≤0.07) is determined by weighing an excess of lithium aluminum hydride (the excess lithium aluminum hydride should be 20-40% of the actual mass used); simultaneously, the amount of bulk metallic Al is reduced according to the stoichiometric ratio. Since lithium aluminum hydride is easily decomposed and volatilized, this invention uses an excess of lithium aluminum hydride to avoid raw material loss affecting the elemental content of the product.

[0044] Preferably, in this invention, lithium aluminum hydride powder is added to alloy powder in a glove box, ground and mixed evenly, the resulting mixed powder is added to a molybdenum crucible, placed in a sealed bag, and transferred from the glove box to a pressure sintering furnace. The mixed powder is placed in the sintering furnace, the pressure sintering furnace is evacuated to a vacuum state of <0.1 Pa, high-purity nitrogen (99.99% purity) is introduced, the temperature is raised to the sintering temperature, cooled to room temperature with the furnace, and ground to obtain a fluorescent conversion type red phosphor for display.

[0045] In this invention, the temperature of the gas pressure sintering is preferably 1050-1100℃, more preferably 1080℃, and the time is preferably 4-6h, more preferably 5h; the nitrogen pressure of the gas pressure sintering is preferably 0.4-0.6MPa, more preferably 0.5MPa; and the heating rate to the temperature of the gas pressure sintering is preferably 15℃ / min.

[0046] The present invention does not impose any special limitations on the grinding process; it can be carried out according to a process known in the art.

[0047] The present invention provides a display fluorescent conversion type red phosphor prepared by the preparation method described in the above technical solution.

[0048] In this invention, the display fluorescent conversion type red phosphor contains Eu. 2+ The total Eu element has a molar percentage of >70%, more preferably 77.4%; blue light with a wavelength of 450-500 nm is used as the excitation source for irradiation, and the display fluorescent conversion type red phosphor exhibits luminescence characteristics with an emission spectrum peak of 652 nm and a half-width of 52 nm.

[0049] In this invention, 95% of the particle size of the fluorescent conversion red phosphor for display is distributed between 2 and 9 μm, with an average particle size of 5.42 μm.

[0050] This invention provides the application of the fluorescence-converting red phosphor for display described in the above technical solution in the field of laser display. This invention does not specifically limit the method of application; any method well-known in the art can be used.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] According to the chemical formula Sr 0.995 Eu 0.005The stoichiometric ratios of Sr, Al, Li, and Eu in LiAl3N4 were determined by weighing 2.934 g of bulk Sr, 1.271 g of bulk Al, and 0.026 g of bulk Eu in a glove box. All the weighed bulk metals were sealed in the same sealed bag and transferred from the glove box to a vacuum arc melting furnace, maintaining a vacuum level <5 × 10⁻⁶. -3 Pa, the melting temperature was adjusted to 1500-1800℃ according to the color and morphology of the alloy block, the ignition time lasted for 15s each time, the melting was turned over 3 times under argon atmosphere, and the metal alloy block was naturally cooled to room temperature. The obtained metal alloy block was transferred to the glove box in a sealed bag, crushed and ground to obtain alloy powder.

[0054] Weigh 0.386 g of LiAlH4 powder and add it to the alloy powder in a glove box. Grind and mix evenly in an agate mortar, transfer to a molybdenum crucible, place in a sealed bag, and transfer to a pressure sintering furnace. Evacuate the furnace to a vacuum of <0.1 Pa, introduce high-purity nitrogen (99.99% purity), and heat to 1050 °C at a heating rate of 15 °C / min. Calcinate for 5 h under a nitrogen pressure of 0.5 MPa in the furnace, cool to room temperature with the furnace, and grind to obtain the red phosphor Sr. 0.995 LiAl3N4:0.005Eu 2+ .

[0055] Example 2

[0056] According to the chemical formula Sr 0.993 Eu 0.007 The stoichiometric ratios of Sr, Al, Li, and Eu in LiAl3N4 were determined. 2.93 g of bulk Sr, 1.301 g of bulk Al, and 0.036 g of bulk Eu were weighed out and sealed in the same bag. The bag was then transferred from the glove box to a vacuum arc melting furnace, with the vacuum level controlled to be <5 × 10⁻⁶. -3 Pa, the melting temperature was adjusted to 1500-1800℃ according to the color and morphology of the alloy block, the ignition time lasted for 15s each time, the melting was turned over 3 times under argon atmosphere, and the metal alloy block was naturally cooled to room temperature. The obtained metal alloy block was transferred into a glove box in a sealed bag, crushed and ground to obtain alloy powder.

[0057] 0.356 g of LiAlH4 powder was added to the alloy powder in a glove box and thoroughly ground and mixed in an agate mortar to obtain a mixed powder. The mixed powder was then transferred to a molybdenum crucible. The molybdenum crucible containing the mixed powder was placed in a sealed bag and transferred to a gas pressure sintering furnace. The furnace was evacuated to a vacuum state with a vacuum degree of <0.1 Pa, and high-purity nitrogen (purity 99.99%) was introduced. The temperature was increased to 1100 °C at a heating rate of 15 °C / min, and calcined for 4 h under the conditions of nitrogen pressure of 0.4 MPa in the sintering furnace. After cooling to room temperature in the furnace, the powder was ground to obtain the red phosphor Sr. 0.993 LiAl3N4:0.007Eu 2+ .

[0058] Example 3

[0059] According to the chemical formula Sr 0.997 Eu 0.003 The stoichiometric ratios of Sr, Al, Li, and Eu in LiAl3N4 were determined. 2.938 g of bulk Sr, 1.256 g of bulk Al, and 0.016 g of bulk Eu were weighed out respectively. All the weighed bulk metals were sealed in the same sealed bag and transferred from the glove box to a vacuum arc melting furnace, controlling the vacuum level to <5 × 10⁻⁶. -3 Pa, the melting temperature was adjusted to 1500-1800℃ according to the color and morphology of the alloy block, the ignition time lasted for 15s each time, the melting was turned over 3 times under argon atmosphere, and the metal alloy block was naturally cooled to room temperature. The obtained metal alloy block was transferred into a glove box in a sealed bag, crushed and ground to obtain alloy powder.

[0060] 0.327 g of LiAlH4 powder was added to the alloy powder in a glove box and thoroughly ground and mixed in an agate mortar to obtain a mixed powder. The mixed powder was then transferred to a molybdenum crucible. The molybdenum crucible containing the mixed powder was placed in a sealed bag and transferred to a gas pressure sintering furnace. The furnace was evacuated to a vacuum state with a vacuum degree of <0.1 Pa, and high-purity nitrogen (99.99% purity) was introduced. The temperature was increased to 1050 °C at a heating rate of 15 °C / min, and calcined for 6 h under the conditions of nitrogen pressure of 0.6 MPa in the sintering furnace. After cooling to room temperature in the furnace, the powder was ground to obtain the red phosphor Sr. 0.997 LiAl3N4:0.003Eu 2+ .

[0061] Example 4

[0062] According to the chemical formula Sr 0.995 Eu 0.005The stoichiometric ratios of Sr, Al, Li, and Eu in LiAl3N4 were determined by weighing 2.934 g of bulk Sr, 1.271 g of bulk Al, and 0.026 g of bulk Eu in a glove box. All the weighed bulk metals were sealed in the same sealed bag and transferred from the glove box to a vacuum arc melting furnace, maintaining a vacuum level <5 × 10⁻⁶. -3 Pa, the melting temperature was adjusted to 1500-1800℃ according to the color and morphology of the alloy block, the ignition time lasted for 15s each time, the melting was turned over 3 times under argon atmosphere, and the metal alloy block was naturally cooled to room temperature. The obtained metal alloy block was transferred to the glove box in a sealed bag, crushed and ground to obtain alloy powder.

[0063] Weigh 0.386 g of LiAlH4 powder and add it to the alloy powder in a glove box. Grind and mix thoroughly in an agate mortar until homogeneous. Transfer the mixture to a molybdenum crucible, place it in a sealed bag, and transfer it to a pressure sintering furnace. Evacuate the furnace to a vacuum of <0.1 Pa, introduce high-purity nitrogen (99.99% purity), and heat to 1080 °C at a rate of 15 °C / min. Calcinate for 4 h under a nitrogen pressure of 0.6 MPa in the furnace. Cool to room temperature with the furnace, grind, and obtain the red phosphor Sr. 0.995 LiAl3N4:0.005Eu 2+ .

[0064] Comparative Example 1

[0065] According to the chemical formula Sr 0.995 Eu 0.005 The stoichiometric ratios of Sr, Al, Li, and Eu elements in LiAl3N4 were determined. In a glove box, 0.965 g of Sr3N2 powder, 0.737 g of AlN powder, 0.456 g of LiAlH4 powder, and 0.011 g of EuF3 powder were weighed out, respectively. These raw materials were ground and mixed evenly in an agate mortar, transferred to a molybdenum crucible, placed in a sealed bag, and then transferred to a pressure sintering furnace. The furnace was evacuated to a vacuum of <0.1 Pa, and high-purity nitrogen (99.99% purity) was introduced. The temperature was increased to 1050 °C at a rate of 15 °C / min, and calcined for 5 hours under a nitrogen pressure of 0.5 MPa. After cooling to room temperature in the furnace, the mixture was ground to obtain the red fluorescent powder Sr. 0.995 LiAl3N4:0.005Eu 2+ .

[0066] Characterization and testing

[0067] Figure 1 shows the XRD patterns of the red phosphors prepared in Examples 1-4. Figure 1 shows that all diffraction peaks correspond one-to-one with the ICSD standard data cards, and no impurity peaks were observed. The results indicate that pure-phase red phosphors were successfully prepared using alloying and nitriding methods under different reaction conditions.

[0068] Figures 2 and 3 show the excitation and emission spectra of the red phosphor prepared in Example 2, respectively. As can be seen from Figures 2 and 3, under blue light excitation at a wavelength of 460 nm, the emission spectrum of the red phosphor is in the range of 620–680 nm, with an emission peak at 652 nm, indicating that the phosphor emits red light. The half-width at half-maximum (WHM) of the emission spectrum is 52 nm, indicating that the phosphor exhibits narrow-band red emission. The excitation spectrum of the red phosphor prepared in Example 2 covers the blue light region and can be effectively excited by a blue light chip, meeting the application requirements of fluorescence conversion laser display technology.

[0069] Figure 4 shows the scanning electron microscope (SEM) spectrum (a) and particle size distribution (b) of the red phosphor prepared in Example 1. As can be seen from Figure 4, the prepared red phosphor has a relatively uniform particle size distribution, a relatively smooth surface, and good dispersibility; 95% of the particles are distributed in the range of 2 to 9 μm, and the average particle size is 5.42 μm.

[0070] Figures 5 and 6 are the quantum efficiency spectra of the red phosphors prepared in Example 1 and Comparative Example 1, respectively. The standard sample is the standard reflectance sample - barium sulfate. The inset is a magnified view of a part. As can be seen from Figures 5 and 6, the red phosphor prepared in Example 1 has an external quantum efficiency of up to 52.38%, while the quantum efficiency of the red phosphor prepared in Comparative Example 1 is only 31.36%.

[0071] Figure 7 shows the X-ray near-edge absorption (XANES) spectrum of the red phosphor prepared in Example 1. The Eu content in the prepared phosphor was calculated from the XANES spectrum. 2+ The red phosphor of this invention has a molar percentage of 77.4% in the total Eu element. Therefore, it has high quantum efficiency and great application potential in the field of fluorescence conversion laser display technology.

[0072] Figure 8 shows the luminous flux (a) and emission spectrum (b) of the red phosphor prepared in Example 1 under different laser power excitation conditions as the incident laser power density increases. As can be seen from Figure 8, with increasing laser power, the phosphor sample exhibits a very high luminescence saturation threshold of 72.64 W / mm². 2 Combined with the emission spectrum (b), the chromatic coordinates were calculated, and the results showed that at 21 W / mm²... 2 Under power density laser excitation, its CIE-X value is 0.7026. This indicates that the red phosphor of this invention has great application potential in the field of fluorescence conversion laser display technology.

[0073] Figure 9 shows the emission spectra of the red phosphor prepared in Example 1 at different temperatures (25-225℃). As can be seen from Figure 9, the red phosphor prepared by the alloying method of the present invention has an integrated emission intensity of 95.6% at 150℃, indicating that the red phosphor of the present invention has excellent thermal stability.

[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a fluorescence-converting red phosphor for display, characterized in that, Includes the following steps; The chemical formula of the fluorescence-converting red phosphor used in the display is: Sr (1-x) Eu x LiAl3N4, where 0.001≤x≤0.007; According to the chemical formula Sr (1-x) Eu x The required stoichiometric ratio for LiAl3N4 is obtained by mixing metallic Sr, metallic Al, and metallic Eu, followed by vacuum melting under a protective atmosphere, and then crushing and grinding to obtain alloy powder. According to the chemical formula Sr (1-x) Eu x The required stoichiometric ratio of Li element in LiAl3N4 is determined by grinding and mixing lithium aluminum hydride with the alloy powder, and then sintering the resulting mixed powder under gas pressure in a nitrogen atmosphere to obtain a fluorescent conversion type red phosphor for display. The total amount of Al in the metallic Al and lithium aluminum hydride reaches the chemical formula Sr (1-x) Eu x The required stoichiometric ratio of Al in LiAl3N4.

2. The preparation method according to claim 1, characterized in that, The protective gas used in the protective atmosphere includes argon.

3. The preparation method according to claim 1 or 2, characterized in that, The conditions for vacuum melting include: a temperature of 1500–1800℃, an ignition time of 10–20 seconds per ignition, and a vacuum degree of <5×10⁻⁶. -3 Pa.

4. The preparation method according to claim 1, characterized in that, The theoretical mass is the mass of lithium aluminum hydride corresponding to the required stoichiometric ratio of Li, and the actual added mass of lithium aluminum hydride is 20-40% of the theoretical mass.

5. The preparation method according to claim 1 or 4, characterized in that, The pressure sintering temperature is 1050–1100℃, and the time is 4–6 hours.

6. The preparation method according to claim 5, characterized in that, The nitrogen pressure during the gas pressure sintering is 0.4–0.6 MPa.

7. The display fluorescent conversion red phosphor prepared by the preparation method according to any one of claims 1 to 6.

8. The display phosphor with fluorescence conversion according to claim 7, characterized in that, The display fluorescent conversion red phosphor contains Eu 2+ The molar percentage of total Eu is >70%.

9. The display phosphor with fluorescence conversion according to claim 7, characterized in that, Using blue light with a wavelength of 450–500 nm as the excitation source, the display uses a fluorescent conversion type red phosphor to exhibit luminescence characteristics with an emission spectrum peak of 652 nm and a half-width of 52 nm.

10. The application of the display phosphor-converting red phosphor according to any one of claims 7 to 9 in the field of laser display.

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