Fluoride fluorescent powder as well as preparation method and application thereof

Abstract

The invention discloses fluoride fluorescent powder and a preparation method and application thereof.The fluoride fluorescent powder contains an inorganic compound with the chemical general formula being AaDbEcMm, the inorganic compound has the crystal structure identical to that of a monoclinic system K3TiF7 or K3GeF7, the space group of the inorganic compound is C2 / c, and by selecting the types and content of elements of the inorganic compound, the content of the elements of the inorganic compound is increased, and the content of the elements of the inorganic compound is increased. The inorganic compound provided by the invention can emit red light with a peak wavelength range of about 600-650nm under the excitation of light with a wave band of 400-470nm, has the advantages of higher emission intensity and narrower half-peak width, is matched with the excitation wave band of a blue light LED chip, and can be used for realizing the purpose of enhancing the luminous efficiency. Good application prospects are realized in the fields of backlight sources for ultra-high color gamut display and the like.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of luminescent materials, and in particular to a fluoride phosphor and a preparation method and application thereof. Background Art

[0002] With the rapid development of information technology, flat-panel display devices have continuously achieved breakthroughs in lightweighting, high resolution, and high color saturation. Liquid crystal display (LCD) technology, with its advantages such as stable performance, low energy consumption, and long life, remains dominant in the current flat-panel display market. In LCD systems, the choice of backlight source plays a crucial role in image clarity, color rendering, and overall color gamut coverage. In recent years, with the continuous advancement of display technology, white LEDs using a single blue LED chip paired with one or more phosphors have gradually become the mainstream choice. This configuration not only offers longer life, reduced light attenuation, lower manufacturing costs, and more stable light color characteristics, but also effectively replaces traditional backlight technologies such as cold cathode fluorescent lamps (CCFLs), driving further development in the LCD field. Currently, there are three main implementation methods for phosphor-converted white LEDs, with the most common combination being a blue LED chip combined with red and green phosphors. By precisely controlling the type and ratio of red and green phosphors, diverse light source requirements can be met for different application scenarios. This combination not only optimizes color performance, but also ensures color consistency and brightness uniformity of display devices in various environments while maintaining high color saturation, and is gradually becoming the main implementation path for white light LEDs.

[0003] Color gamut, one of the core metrics for evaluating display device performance, reflects a device's ability to reproduce natural colors. The wider the color gamut, the more colors a display can cover, and the more vivid and lifelike the images it presents. While LCD display technology using LEDs as backlights offers significant advantages in lifespan, production process maturity, and cost control, its color gamut performance still has room for improvement compared to emerging display technologies such as OLED and QLED, making it difficult to fully meet users' growing visual experience needs. Therefore, expanding the color gamut has become a key issue that LCD display technology urgently needs to address.

[0004] According to the working principle of liquid crystal display, the light emitted by the backlight source needs to pass through the color filter to separate the three independent spectra of red (R), green (G), and blue (B), and then combine them into a variety of colors. Only when the spectrum of the backlight source and the spectrum of the filter are highly matched can the light be effectively transmitted through the filter without causing significant loss of light intensity. Therefore, the green and red phosphors that make up the white light LED need to have narrow spectral band emission characteristics, and the corresponding red and green phosphors are required to have a high level of light efficiency. However, the red phosphors currently used for display, such as K2SiF6:Mn 4+ , luminous efficiency performance has reached a bottleneck. Therefore, to meet the market's greater demand for high color gamut, it is urgent to develop a new red phosphor system to further improve the color gamut performance of LCD devices and meet the needs of the high-end display market.

[0005] In summary, expanding the color gamut of LCD technology will not only enhance the realism and visual impact of displays, but will also promote the widespread application and adoption of display technology in a variety of fields, including consumer electronics, professional displays, and medical imaging. To this end, the development of new high-purity, narrow-bandwidth red phosphor systems has become a key direction in the development of LCD technology. This will not only help address bottlenecks in existing technologies but also provide a solid material foundation for the innovation of future high-performance display devices. Summary of the Invention

[0006] (1) Purpose of the invention

[0007] The purpose of the present invention is to provide a fluoride phosphor and its preparation method and application, so as to meet the application end's demand for higher light efficiency of red phosphor and provide a high-efficiency new red fluorescent material for high-performance display equipment.

[0008] (2) Technical solution

[0009] At present, red phosphors are mainly concentrated in Eu 3+ 、Eu 2+ Cr 3+ or Mn 4+ ions as activation centers. 3+ The excitation-emission of Eu belongs to ff transition. Since its 4f electrons are in the internal energy level, the emission spectrum has a narrow feature and high color purity. 2+ The excitation-emission belongs to the 4f-5d transition, with 4f 7 5d 1The electronic configuration of Cr is relatively exposed, and is easily affected by the strong influence of the surrounding crystal field, resulting in a large energy level splitting. Therefore, it can emit red light of different wavelengths in different crystal environments. The emission spectrum is usually wide, with a half-peak width generally above 100nm. However, in some rigid crystal structures, the emission spectrum width can be controlled to a certain extent. 3+ and Mn 4+ The excitation-emission belongs to dd transition, especially Mn 4+ The electronic configuration is 3d 3 , can achieve efficient red light emission under appropriate crystal field, the emission wavelength is usually in the range of 620-700nm, and the emission spectrum half-peak width is narrow and the color purity is high. 4+ Not only does it have high color purity and high energy efficiency, its excited state non-radiative transition loss is low, and it has excellent thermal stability and is suitable for high temperature working environments. 4+ The energy level structure of Mn has good energy level matching with a variety of main activators, which facilitates energy transfer and improves the overall luminescence performance. 4+ It has shown significant advantages in LED and display technology and has broad application prospects, although its luminous efficiency still has room for improvement. 4+ With its high color purity, high energy efficiency, good thermal stability and environmental friendliness, it is a highly competitive activator in red phosphors.

[0010] In combination with the above theory, the first aspect of the present invention provides a fluoride phosphor containing an inorganic compound having the same crystal structure as monoclinic K3TiF7 or K3GeF7 and a space group of C2 / c. K3TiF7 and K3GeF7 are a new type of crystal structure. 4+ Mainly occupied Ti 4+ 、Ge 4+ The chemical formula of the inorganic compound is A a D b E c M m , where component A includes Li, Na, K, Rb, Cs, At least one of Mg, Ca, Sr and Ba elements or ionic groups; wherein Li + 、Na + , K + , Rb + 、Cs + Mg 2+ , Ca 2+ 、Sr 2+ 、Ba 2+ Chemical properties belong to I A or II AGroup elements, active chemical properties, Active chemical properties can also be used to replace Li + 、Na + , K + , Rb + 、Cs + The elements are regarded as positive monovalent ionic groups and as important components in the K3TiF7 and K3GeF7 type crystal structures. They can replace each other without changing the matrix structure, and the luminescence properties can be adjusted according to needs.

[0011] The D component includes at least one of Ti, Zr, Hf, Si, Ge and Sn elements; Ti, Hf and Zr in the D component belong to IV B Group elements, Si, Ge, Sn all belong to IV A The E component is at least one of F, Cl, Br, I and O. In the E component, F, Cl, Br, I and O affect the crystal field environment of the luminescence center through the difference in electronegativity of the anions, and have the characteristics of stabilizing the luminescence performance of the luminescence center. The M component includes one or two of Mn and Eu elements, and at least contains Mn element. The doping of Mn and Eu elements in the M component utilizes energy transfer to improve the absorption efficiency of the original single-doped Mn within the excitation range, thereby promoting the improvement of emission intensity and external quantum efficiency.

[0012] Furthermore, in the general chemical formula of the inorganic compound, 2≤a≤3.5, 0.6≤b≤1.4, 6≤c≤8, 0.001≤m≤0.3, preferably, 2.8≤a≤3.2, 0.8≤b≤1.2, 6.8≤c≤7.2.

[0013] Furthermore, the component A contains at least K, and the molar percentage of K in the component A is 50% to 100%.

[0014] Furthermore, the D component contains at least Ti and Ge, and the total molar percentage of Ti and Ge in D is 50% to 100%. Preferably, the D component is Ti or Ge.

[0015] Furthermore, the E component is one or two of the elements F, Cl, Br, I and O, and contains at least F, and the molar percentage of F in the E is greater than 50%. Preferably, the E component is F.

[0016] Furthermore, the fluoride phosphor can emit red light with a peak wavelength range of 600-650 nm after being excited by light with a peak wavelength range of 400-470 nm.

[0017] A second aspect of the present invention provides a method for preparing the fluoride phosphor described in any one of the above descriptions, comprising:

[0018] According to the chemical formula A a D b E c M m The stoichiometric ratios of each element were weighed and mixed as follows:

[0019] S1, mixing a D-containing compound, part of an A-containing compound, and an M-containing compound, and dissolving the mixed raw materials in a 30-50% (mass concentration percentage) HF aqueous solution to prepare a first solution; wherein the D-containing compound includes at least one of a D-containing fluoride and an oxide, and the M-containing compound includes at least one of a fluoromanganate, a manganese oxide, and a europium-containing compound; and the mass concentration percentage of the D compound solution is 10-15%.

[0020] S2. Dissolving the remaining portion of compound A in an organic acid, heating and stirring, to prepare a second solution. The organic acid is at least one of trifluoromethanesulfonic acid, benzenesulfonic acid, citric acid, formic acid, and oleic acid. The mass concentration of the organic acid solution used should be between 10% and 15%. If the mass concentration of the organic acid is too low, the corresponding phosphor grains cannot be efficiently obtained. If the concentration of the acid solution is too high, the quality of the phosphor grains will be affected, making it impossible to reasonably evaluate the performance of the corresponding phosphor.

[0021] S3, dropwise adding the second solution to the first solution and heating the solution. The reaction product is filtered to obtain a precipitate. The second solution is added at a rate of 5 to 12 ml / min. A too fast addition rate is detrimental to the growth of fluoride phosphor crystals, resulting in low luminous efficiency. A too slow addition rate has no significant adverse effect on crystal growth, but consumes a significant amount of time and cost.

[0022] S4. The precipitate is washed with a 2% to 5% (mass concentration) HF aqueous solution and a detergent, followed by drying to obtain a fluoride phosphor powder. The detergent comprises ethanol or acetone. The precipitate is first washed with a 2% to 5% (mass concentration) HF aqueous solution with stirring three times, and then washed twice with ethanol or acetone. The washed precipitate is then air-dried at a temperature of 60 to 100° C. to obtain the corresponding fluoride phosphor powder.

[0023] Furthermore, the heating and stirring temperature in step S2 is 10-70°C. A temperature too low is not conducive to the growth of fluoride crystals, while a temperature too high can cause changes in the Mn valence state of the reaction system, reducing luminous efficiency. The heating and stirring time is 50-150 minutes. Insufficient stirring time will result in the first solution and the second solution not being mixed evenly, while excessive stirring time can easily lead to excessively large particle size, which cannot meet application requirements.

[0024] A third aspect of the present invention provides a light-emitting device comprising a housing, an excitation light source, and a fluoride phosphor. The excitation light source is fixedly connected to the fluoride phosphor and encapsulated in the housing. The fluoride phosphor comprises the fluoride phosphor described in any one of the above descriptions or the fluoride phosphor obtained by the preparation method described in any one of the above descriptions.

[0025] Furthermore, the excitation light source is a semiconductor chip with an emission peak wavelength range of 400-470nm. The excitation light source adopts a GaN light-emitting chip with a main emission wavelength range of 400-470nm. Preferably, the fluoride fluorescent material used in this scheme has a characteristic excitation peak at a wavelength of 460nm, corresponding to the excitation spectrum of the semiconductor chip, thereby obtaining a significantly improved Stokes luminescence efficiency. More preferably, by accurately mixing the fluoride phosphor with a green phosphor (or quantum dot green light material) with an emission wavelength of 510-540nm, and then implementing a multi-layer packaging structure with a blue light semiconductor chip, a display device with high color purity and wide color gamut coverage can be synergistically produced.

[0026] (3) Beneficial effects

[0027] The above technical solution of the present invention has the following beneficial technical effects: The present invention provides a fluoride phosphor and its preparation method and application, wherein the inorganic compound is a monoclinic material and its space group is C2 / c. The fluoride phosphor has a composition formula of A a D b E c M m The chemical composition of the fluoride phosphor of the present invention can be characterized as A a D b E c M m The innovation of this type of inorganic compound is mainly reflected in the coordinated design of the element system and the combination effect of specific elements. In the material design, each component element realizes crystal field regulation and luminescence performance optimization through the following functional division of labor. Component A is the matrix cation of the fluoride phosphor, which is selected from alkali metals (Li + 、Na + , K+ , Rb + 、Cs + ), Alkaline earth metals (Mg 2+ , Ca 2+ 、Sr 2 + 、Ba 2+ ) and other metal ions or ionic groups, primarily responsible for charge balance and lattice stabilization of the crystal structure. The chemically active alkali metals (Li, Na, K, Rb, Cs) in component A form a stable charge compensation system with component D, reducing the lattice oxygen vacancy concentration and achieving a stable crystal structure. Component D is a coordination center, selected from at least one of Ti, Zr, Hf, Si, Ge, and Sn. Through strong covalent bonds, it constructs a stable [DE6] octahedral structural framework, providing ample and stable structural substitution sites for component M, thereby achieving stable luminescence properties. In particular, the Ti and Ge elements in this compound have stable valences (+4) and a stable coordination environment, which not only enhances the rigidity of the crystal structure but also broadens the excitation spectrum response range through charge transfer bands. The E component is a coordinating anion of the D component, selected from at least one of F, Cl, Br, I, and O, responsible for regulating the local coordination environment of the luminescence center and having the function of stabilizing the luminescence performance of the luminescence center. Among them, the F element (fluorine) is the core constituent element of the E component, and its extremely strong electronegativity of up to 3.98 (Pauling scale) plays a key role in optimizing the material properties and can ensure that the luminescence center is in a stable octahedral crystal field environment. The M component is a luminescence center, including one or two of the Mn and Eu elements, and at least contains the Mn element Mn. 4+ The electronic configuration is 3d 3, efficient red light emission can be achieved under appropriate crystal fields. The present invention achieves precise control of luminescence characteristics and spectral performance by rationally designing the composition of the inorganic compound. The energy level structure of the luminescence center is optimized, allowing the material to efficiently absorb light energy within a specific excitation wavelength range, thereby improving the absorption efficiency of the doping element. The inorganic compound can produce high-intensity red light emission with a peak wavelength range of 600-650nm under light excitation in the 400-470nm band. This red light has a high emission intensity and a narrow half-maximum width (<10nm), ensuring the purity and saturation of the luminescent color. At the same time, the strongest point of the excitation band (460nm) is highly matched with the emission band of the blue light LED chip (GaN emission wavelength is 460nm). The strongest point of the excitation band is the same as the emission wavelength of the blue light LED chip, indicating that all the blue light emitted by the chip is used to be absorbed by the luminescence center, achieving maximum utilization of the energy of the blue light LED and improving light conversion efficiency. This matching not only helps to reduce energy loss, but also effectively improves the color expression and brightness of the display device. The inorganic compound has the same crystal structure as K3TiF7 and K3GeF7 (monoclinic system) and the space group is C2 / c. The structural substance is Mn 4+ A unique placeholder environment is provided, which ensures the stability and high light output of the material while improving the luminous efficiency of the luminescent material. Therefore, the fluoride phosphor (luminescent material) shows broad application prospects in the fields of ultra-high color gamut display backlight, intelligent lighting, display devices and high-efficiency energy conversion equipment. Especially in the context of current display technology pursuing higher color accuracy and wider color gamut coverage, the luminescent material can significantly improve the visual effect of the display and meet the demanding demand for display quality in the high-end market. In addition, by virtue of its excellent thermal stability and light efficiency, the luminescent material of the present invention is also expected to play an important role in applications such as high-power lighting and industrial light sources, and promote the technological progress and development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the spatial structure of space group C2 / c materials (standard crystal structure);

[0029] Figure 2 Schematic diagram of the spatial structure and XRD diffraction pattern of the luminescent material sample prepared in Example 1 of the present invention; Figure 2 (a) Schematic diagram of the spatial structure of the luminescent material sample prepared in Example 1, Figure 2 (b) is the XRD diffraction pattern of the luminescent material sample prepared in Example 1;

[0030] Figure 3 1 is an excitation and emission spectrum diagram of an experimental sample of the luminescent material prepared in Example 1 of the present invention; Figure 3(a) is the emission spectrum of the sample prepared in Example 1 at 460 nm excitation. Figure 3 (b) is a 627 nm excitation spectrum of the luminescent material sample prepared in Example 1;

[0031] Figure 4 Schematic diagram of the spatial structure and XRD diffraction pattern of the luminescent material sample prepared in Example 2 of the present invention; Figure 4 (a) Schematic diagram of the spatial structure of the luminescent material sample prepared in Example 2, Figure 4 (b) is the XRD diffraction pattern of the luminescent material sample prepared in Example 2;

[0032] Figure 5 1 is an excitation and emission spectrum diagram of an experimental sample of a luminescent material prepared in Example 2 of the present invention; Figure 5 (a) is an emission spectrum of the luminescent material sample prepared in Example 2 at 460 nm excitation;

[0033] Figure 5 (b) is the 627nm excitation spectrum prepared in Example 2. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0035] Comparative Example 1

[0036] The molecular formula is K2Ti 0.98 F6Mn 0.02 The compound (the constituent elements are shown in Table 1) is prepared, and its luminescence intensity under 460nm blue light excitation is set to 100. The specific steps are as follows: weigh 58.10g potassium fluoride (KF), 39.90g titanium dioxide (TiO2) and 0.87g manganese dioxide (MnO2), and mix the above raw materials evenly according to the stoichiometric ratio; dissolve the mixed raw materials in 240mL of a 40% mass concentration of hydrofluoric acid (HF) aqueous solution, and add 10mL of a 30% mass concentration of hydrogen peroxide (H2O2) as an oxidant, and stir thoroughly until completely dissolved to prepare a first solution. During the dissolution process, the solution temperature is maintained at 50°C in a water bath to ensure that TiO2 and MnO2 fully react to generate H2TiF6 and H2MnF6, while maintaining the Mn element in a tetravalent state. Subsequently, the solution is allowed to stand in a constant temperature water bath at 60°C for 24 hours to allow K2Ti 0.98 F6Mn 0.02Crystals gradually precipitated. After the reaction was completed, the precipitate was collected by filtration using a polytetrafluoroethylene filter membrane and washed three times with a 5% dilute HF solution and deionized water to remove unreacted fluoride and by-products. Finally, the washed precipitate was placed in a vacuum drying oven and dried at 80°C for 8 hours, followed by annealing at 250°C in an inert gas (Ar) atmosphere for 4 hours to ensure that the Mn element remained in a tetravalent state and obtained a stable crystal structure, ultimately obtaining the target product K2Ti 0.98 F6Mn 0.02 .

[0037] Example 1

[0038] This embodiment provides a K3Ti 0.95 F7M 0.05 The phosphor is prepared as follows: 87.15g of potassium fluoride (KF), 0.25g of manganese tetrafluoride (MnF4), and 37.94g of titanium oxide (TiO2) are weighed and dissolved in 300g of a 40% (by mass) hydrofluoric acid (HF) aqueous solution, and stirred thoroughly until completely dissolved to obtain a first solution. Simultaneously, 52.59g of potassium fluoride (KF) is dissolved in 200g of a 10% (by mass) trifluoromethanesulfonic acid solution to obtain a second solution. Subsequently, the second solution is slowly injected into the first solution at a rate of 5mL / min and mechanically stirred at 55°C for 2 hours to ensure sufficient reaction. After the reaction is completed, the supernatant is removed by centrifugation or filtration, and the precipitate is retained. The precipitate is washed three times with a 4% (by mass) HF aqueous solution to remove impurities, and then washed three times with acetone for further purification. Finally, the washed precipitate is dried at 100°C to obtain the fluorescent material K3TiO2. 0.95 F7M 0.05 The crystal structure of the luminescent material obtained in Example 1 was analyzed by single crystal X-ray spectroscopy. The main phase of the luminescent material has a crystal structure of K3TiF7 and a space group of C2 / c. Figure 2 (a) is shown. Its XRD is as follows Figure 2 As shown in (b), the results are basically consistent with the standard XRD results of K3TiF7. Figure 1 This is a schematic diagram of the standard crystal structure (created using Vesta software) based on the symmetry of the C2 / c space group, generally referring to a class of materials belonging to the C2 / c space group. Fluorescence spectrophotometry analysis of its luminescence properties revealed that this material exhibits narrow-spectrum red luminescence under 460nm blue light excitation, with a peak wavelength of 628nm and a relative luminous intensity of 117.2. Figure 3 The excitation and emission spectra of the luminescent material sample prepared in this embodiment are shown in FIG. Figure 3 (b) is the excitation spectrum of the luminescent material sample prepared in this embodiment at 627 nm, Figure 3 (a) is the emission spectrum of the luminescent material sample prepared in this embodiment at 460nm excitation. Figure 3 It can be seen that the luminescent material has high absorption intensity in the blue light region and the emission spectrum ranges from 600 to 650 nm.

[0039] Example 2

[0040] This embodiment provides a K3Ge 0.95 F7M 0.05 The phosphor is prepared as follows: 87.15g of potassium fluoride (KF), 3.27g of manganese tetrafluoride (MnF4) and 49.70g of germanium oxide (GeO2) are weighed and dissolved in 280g of a 35% by mass hydrofluoric acid (HF) aqueous solution, and stirred thoroughly until completely dissolved to obtain a first solution; at the same time, 50.00g of potassium fluoride (KF) is dissolved in 180g of a 12% by mass benzenesulfonic acid aqueous solution to obtain a second solution. Subsequently, the second solution is slowly injected into the first solution at a rate of 4mL / min and mechanically stirred at 58°C for 1.8 hours to ensure that the reaction is fully carried out. After the reaction is completed, the supernatant is removed by centrifugation or filtration, and the precipitate is retained; the precipitate is washed three times with a 3.5% (mass concentration percentage) HF aqueous solution to remove impurities, and then washed three times with ethanol for further purification. Finally, the washed precipitate is dried at 95°C to obtain a block fluoride phosphor K3Ge 0.95 F7M 0.05 Through the above steps, high-purity and structurally stable K3Ge can be prepared. 0.95 F7M 0.05 Phosphors are suitable for various optoelectronic applications, such as LED lighting, display devices and lasers. Single crystal X-ray diffraction analysis was performed on the sample of the embodiment to obtain the crystal structure. The crystal structure is as follows Figure 4 As shown, the main crystal structure is K3GeF7, the space group is C2 / c, and its crystal structure is as follows Figure 4 (a) shows that its XRD is as follows Figure 4 As shown in (b), the result is basically consistent with the standard XRD pattern of K3GeF7. Figure 5 (a) and Figure 5 (b) It can be seen that the luminescence performance of the sample of Example 2 was analyzed by fluorescence spectrometer, and the luminescent material has high absorption intensity in the blue light region and the emission spectrum range is 600-650nm.

[0041] Example 3

[0042] This embodiment provides a Na 1.7 CaHf 0.6 I 6.1 Mn0.001 The phosphor is prepared as follows: 63.70g of sodium iodide (NaI), 73.47g of calcium iodide (CaI2), 102.92g of hafnium iodide (HfI4) and 0.022g of manganese dioxide (MnO2) are weighed and dissolved in 400g of deionized water with a mass concentration of 40%, and stirred until completely dissolved to obtain a first solution; at the same time, 10.00g of sodium iodide (NaI) is dissolved in 450g of a 12% citric acid aqueous solution to obtain a second solution. Subsequently, the second solution is slowly injected into the first solution at a rate of 3.5mL / min and mechanically stirred at 75°C for 2.2 hours to ensure that the reaction is fully carried out. After the reaction is completed, the supernatant is removed by centrifugation or filtration, and the precipitate is retained; the precipitate is washed three times with a 4.5g / L hydrofluoric acid (HF) aqueous solution to remove impurities, and then washed three times with ethanol for further purification. Finally, the washed precipitate was dried at 98°C to obtain the phosphor Na 1.7 CaHf 0.6 I 6.1 Mn 0.001 Through the above steps, high-purity and structurally stable Na 1.7 CaHf 0.6 I 6.1 Mn 0.001 Phosphors are suitable for various optoelectronic applications, such as LED lighting, display devices and lasers.

[0043] Example 4

[0044] This embodiment provides a Na 3.3 Sn 0.7 Br 6.1 Mn 0.001 The preparation method of the phosphor is as follows: weigh 84.88g of sodium bromide (NaBr), 76.71g of tin bromide (SnBr4) and 0.022g of manganese dioxide (MnO2), dissolve the above raw materials in 290g of a 36% hydrofluoric acid aqueous solution, and stir thoroughly until completely dissolved to obtain a first solution; at the same time, dissolve 75.00g of sodium bromide (NaBr) in 190g of a 13% citric acid aqueous solution to obtain a second solution. Subsequently, the second solution is slowly injected into the first solution at a rate of 4mL / min and mechanically stirred at 62°C for 1.9 hours to ensure that the reaction is fully carried out. After the reaction is completed, the supernatant is removed by centrifugation or filtration, and the precipitate is retained; the precipitate is washed three times with a 3.0% (mass concentration percentage) hydrobromic acid (HBr) aqueous solution to remove impurities, and then washed three times with ethanol for further purification. Finally, the washed precipitate is dried at 96°C to obtain a block-shaped bromide phosphor Na3.3 Sn 0.7 Br 6.1 Mn 0.001 Through the above steps, high-purity and structurally stable Na 3.3 Sn 0.7 Br 6.1 Mn 0.001 Phosphors are suitable for various optoelectronic applications, such as LED lighting, display devices and lasers.

[0045] The preparation processes of Examples 5-37 were similar to those of Examples 1-4. The raw powders used and the resulting compounds are shown in Table 1. The compositions of Comparative Example 1 and Examples 1-37, as well as the emission peak wavelengths and relative luminous intensities under 460 nm excitation, are shown in Table 1.

[0046] Table 1 Chemical formula and luminescence properties of comparative examples and embodiments

[0047]

[0048]

[0049]

[0050] It can be seen from Table 1 that under the same preparation conditions, the luminescent material provided by the embodiment of the present invention has improved luminous intensity when excited by the blue light chip compared with the comparative example, which can further improve the luminous efficiency of the narrow-emission red phosphor and meet the application needs in the field of backlight sources for ultra-high color gamut displays.

[0051] According to Examples 3-14, the values ​​of each element in the composition formula of the inorganic substance can be: 2.0≤a≤3.5, 0.6≤b≤1.4, 6.0≤c≤8.0, 0.001≤m≤0.3. Within this condition range, the luminescent material can basically maintain the C2 / c type crystal structure of K3TiF7 and K3GeF7 with the same space group. According to Examples 1, 2 and Examples 15-37, by optimizing the value ranges of component A, component D, and component E, so that 2.8≤a≤3.2, 0.8≤b≤1.2, and 6.8≤c≤7.2, its crystal structure can be further stabilized. Within the above value ranges, the contents of A, D, and E can be lower than or higher than the corresponding stoichiometric ratios to provide a stable luminescent environment for the corresponding luminescent center.

[0052] Comparing Examples 23-30 with Examples 3-22, the elemental composition is further optimized, and the K element is introduced into component A. The molar percentage of K in component A is d, 50%≤d≤100%, which can improve the luminous intensity of the corresponding luminescent material, and its luminous intensity increases with the increase of the K molar percentage.

[0053] Comparing Examples 23-26 with Examples 27-33, further optimizing the elemental composition and introducing Ti and Ge elements into component D can enhance the luminous intensity of the corresponding luminescent materials, and the luminous intensity increases with the increase of the ratio of Ti and Ge elements.

[0054] According to Examples 1-31, the E component can be one or two of the elements F, Cl, Br, I, and O. According to Examples 32-37, the F element is introduced into the E component, and the F element accounts for f, f ≥ 50%. E usually becomes a luminescent center in the luminescent material as an anion component (such as Mn 4+ ) ligands and provide a corresponding crystal field environment for the luminescence center. The F element, the most electronegative element, forms a stable coordination bond with the luminescence center, providing a stable crystal field environment for the luminescence center. Therefore, ensuring that the proportion of F in the E component is greater than 50% can stabilize the crystal environment of the corresponding luminescence center and enhance its luminescence performance.

[0055] According to Examples 1, 2, 36, and 37, it is further determined that component A is K, component D is Ti or Ge, and component E is F. 4+ Ge 4+ Ionic radius and Mn 4+ Similar, Mn 4+ It can be better embedded in the crystal structure to maintain the integrity and stability of the crystal. This good ion matching reduces the generation of lattice defects and helps to improve the optical properties of the luminescent material. Moreover, compared with other elements such as Hf and Zr, Ti 4+ 、Ge 4+ Can more effectively with Mn 4+Energy exchange reduces non-radiative transition pathways, improving overall luminescence efficiency and external quantum efficiency. Element K generally exhibits excellent chemical stability, remaining stable over a wide temperature range and under diverse chemical environments. This allows potassium-containing luminescent materials to maintain excellent performance even under high-temperature operating conditions, extending the lifespan of the luminescent material. Furthermore, in luminescent materials, potassium ions, as dopants or auxiliary ions, can provide a stable environment, reducing the formation of defect states, thereby improving the efficiency and consistency of luminescent centers. This helps enhance the luminescence intensity of the material. Fluorine has the highest electronegativity of all elements, with its electronegativity (F = 3.98) significantly higher than that of oxygen (O = 3.44), chlorine (Cl = 3.16), bromine (Br = 2.96), and iodine (I = 2.66). This extremely high electronegativity gives fluorine a strong electron-withdrawing ability in chemical reactions, significantly affecting the electronic structure and chemical properties of the molecule. Compared to elements O, Cl, Br, and I, the chemical bonds formed between metal ions and F elements have higher bond energies, enabling the corresponding luminescent material to maintain a stable lattice structure.

[0056] According to Examples 1-37 in Table 1, in K3TiF7 and K3GeF7 structural materials, the K element position can be partially or completely replaced by other "+1" or "+2" cations with similar chemical properties, including but not limited to Li + 、Na + , K + , Rb + 、Cs + Mg 2+ , Ca 2+ 、Sr 2+ 、Ba 2+ Plasma, in addition, Ti or Ge elements can be partially or completely replaced by other "+4" cations, including but not limited to Si 4+ 、Sn 4+ , Hf 4+ 、Zr 4+ If the space group of the compound formed by the elements A, D, and E is C2 / c, it can be considered to have the same crystal structure as K3TiF7 and K3GeF7. In addition, under the above conditions, if the stoichiometric ratio of elements A, D, and E is not strictly 3:1:7, as long as it does not change the main crystal structure or the basic luminescence properties, it is considered to have the same crystal structure as K3TiF7 and K3GeF7.

[0057] In addition, according to the data in Table 1, it can be seen that the emission peak wavelength of the luminescent materials with the composition of the present application in Examples 1-37 is 627nm. According to Examples 4-14, it can be seen that the position of component A can be partially or completely replaced by other "+1" or "+2" valent cations with similar chemical properties, including but not limited to Li+ 、Na + , Rb + 、Cs + Mg 2+ , Ca 2+ 、Sr 2+ 、Ba 2 + Plasma, in addition, Ti or Ge elements can be partially or completely replaced by other "+4" cations, including but not limited to Si 4 + 、Sn 4+ , Hf 4+ 、Zr 4+ The E component can be partially or completely substituted by Cl, Br, I, or O. The space groups of the formed compounds are all C2 / c space structures, and they are all narrow-band red luminescent materials.

[0058] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A fluoride phosphor, characterized in that: The fluoride phosphor contains an inorganic compound having the same crystal structure as monoclinic K3TiF7 or K3GeF7 and a space group of C2 / c. The general chemical formula of the inorganic compound is A a D b E c M m , where component A includes Li, Na, K, Rb, Cs, At least one of Mg, Ca, Sr and Ba; the D component includes at least one of Ti, Zr, Hf, Si, Ge and Sn elements; the E component includes at least one of F, Cl, Br, I and O elements; the M component includes one or two of Mn and Eu elements, and at least contains Mn element.

2. The fluoride phosphor according to claim 1, characterized in that: In the general chemical formula of the inorganic compound, 2≤a≤3.5, 0.6≤b≤1.4, 6≤c≤8, and 0.001≤m≤0.

3.

3. The fluoride phosphor according to claim 1 or 2, characterized in that: The component A contains at least K, and the molar percentage of K in the component A is 50% to 100%.

4. The fluoride phosphor according to claim 1 or 2, characterized in that: The D component contains at least Ti and Ge, and the total molar percentage of Ti and Ge in the D component is 50% to 100%.

5. The fluoride phosphor according to claim 1 or 2, characterized in that: The E component is one or two of the elements F, Cl, Br, I and O, and contains at least F. The molar percentage of F in the E is greater than 50%.

6. The fluoride phosphor according to claim 2, characterized in that: In the general chemical formula of the inorganic compound, 2.8≤a≤3.2, 0.8≤b≤1.2, and 6.8≤c≤7.

2.

7. The fluoride phosphor according to claim 1, characterized in that: The A component is K, and the D component is Ti or Ge.

8. The fluoride phosphor according to claim 1, characterized in that: The E component is F.

9. The fluoride phosphor according to claim 1, characterized in that: The fluoride phosphor can emit red light with a peak wavelength range of 600-650nm after being excited by light with a peak wavelength range of 400-470nm.

10. A method for preparing the fluoride phosphor according to claims 1-9, characterized in that: include: According to the chemical formula A a D b E c M m The stoichiometric ratios of each element were weighed and mixed as follows: Mixing a D-containing compound, a portion of an A-containing compound, and an M-containing compound, and dissolving the mixed raw materials in an HF aqueous solution having a mass concentration of 30 to 50%, to prepare a first solution; wherein the D-containing compound comprises at least one of a D-containing fluoride and an oxide, and the M-containing compound comprises at least one of a fluoromanganate, a manganese oxide, and a europium-containing compound; dissolving the remaining portion of compound A in an organic acid, heating and stirring, to prepare a second solution; adding the second solution dropwise to the first solution and heating the mixture, filtering the reactant to obtain a precipitate; The precipitate is washed with an HF aqueous solution with a mass concentration of 2% to 5% and a detergent in sequence, and then dried to obtain fluoride phosphor powder, wherein the detergent comprises at least one of ethanol and acetone.

11. A light-emitting device comprising a housing, an excitation light source and fluoride phosphor, characterized in that: The excitation light source is fixedly connected to the fluoride phosphor and encapsulated in the housing. The fluoride phosphor comprises the fluoride phosphor according to any one of claims 1 to 9.

12. The light emitting device according to claim 11, characterized in that The excitation light source is a semiconductor chip with an emission peak wavelength range of 400-470nm.

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