A kind of fluoride fluorescent powder and its preparation method
The preparation of A2MF6:Mn4+ structured fluoride phosphors by HF-free solution solves the problems of environmental pollution and poor stability, and realizes efficient and safe preparation of fluoride phosphors. It is suitable for near-ultraviolet and blue light excitation and has good moisture resistance and thermal stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LANZHOU UNIV
- Filing Date
- 2025-12-19
- Publication Date
- 2026-07-10
AI Technical Summary
Existing methods for synthesizing Mn4+ doped fluoride phosphors suffer from environmental pollution, safety risks, and poor stability. In particular, they are prone to hydrolysis in humid environments, which leads to a decrease in luminescence intensity.
A fluoride phosphor with an A2MF6:Mn4+ structure was prepared by mixing A2MF6, KMnO4, and MnF2, adding inorganic salts, and then sintering. The surface was coated with A2MF6, and high-efficiency phosphor was obtained by low-temperature short-time sintering and washing with a specific solvent.
It achieves a green and environmentally friendly preparation process, has high luminescence intensity, good moisture resistance and thermal stability, is suitable for large-scale production, is applicable to near-ultraviolet light and blue light excitation, and has a suitable emission spectrum peak position.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of luminescent material preparation technology, specifically relating to a fluoride phosphor and its preparation method. Background Technology
[0002] Mn 4+ Fluoride-doped red phosphors have attracted widespread attention due to their unique narrow-band red light emission, high color purity, and simple preparation methods. However, current synthesis methods often use highly corrosive hydrogen fluoride (HF) as the reaction solution. This process not only causes serious environmental pollution but also poses a threat to human health. Therefore, to achieve a greener and safer synthesis process, there is an urgent need to innovate HF-free synthesis methods. Although several phosphors synthesized using HF-free solutions have emerged in recent years, the luminescence intensity of the resulting phosphors is relatively weak. To overcome this problem and obtain phosphors with higher luminescence efficiency, researchers have tried various HF-free preparation methods; however, these methods have not completely eliminated the generation of HF, and most Mn... 4+ The sources all contain [MnF6]. 2- Precursors of the group (such as CN 112094643 B, a Mn group) 4+ The preparation of fluoride-doped narrow-band red phosphors, including their preparation methods and applications, also relies on HF solution, necessitating the separate construction of HF protection and waste liquid treatment systems and increasing safety risks for operators during material preparation. This indicates that further research is needed to synthesize fluoride phosphors in the absence of HF solution.
[0003] Another factor limiting the practical application of fluoride phosphors is their poor stability in humid environments, due to [MnF6]. 2- The group readily hydrolyzes in water to form manganese hydroxides and oxides. Water molecules can also replace fluorine to form KMnF4·H2O, which darkens the phosphor and severely weakens its luminescence intensity. Therefore, increasing the Mn content... 4+ The waterproof properties of activated fluoride phosphors are crucial. Summary of the Invention
[0004] To address the problems of existing technologies, the purpose of this invention is to provide a novel fluoride phosphor and its preparation method. This preparation method is characterized by its simplicity, low cost, high safety, and suitability for large-scale production. The resulting fluoride red phosphor can be efficiently excited by near-ultraviolet and blue light, exhibiting suitable emission spectrum peak positions, high luminescence intensity, good moisture resistance and waterproof performance, and excellent stability.
[0005] To achieve its purpose, the present invention adopts the following technical solution: The present invention provides a method for preparing a fluoride phosphor, comprising the following steps: Step 1: Mix and grind A2MF6, KMnO4 and MnF2 thoroughly; wherein, A is selected from one or more of the alkali metals Li, Na, K, Rb or Cs; M is selected from one or more of the alkali metals Ti, Si, Ge, Sn or Zr. Step 2: Add inorganic salts to the mixture obtained in Step 1 and grind thoroughly again; Step 3: Place the mixture obtained in Step 2 into a crucible and transfer it to a sintering device. Set the sintering temperature and sintering time. After sintering, obtain the powder product. Step four: Grind the powder product obtained in step three into a fine powder, place it in a solvent, stir and wash it, and dry it to obtain the fluoride red fluorescent powder.
[0006] As a further preferred embodiment of the technical solution of the present invention, in step one, the molar ratio of KMnO4 to MnF2 is 1:3-2:3; the molar ratio of the total amount of KMnO4 and MnF2 to A2MF6 is 0.1:1-0.6:1.
[0007] Furthermore, in step two, the inorganic salt is one of NH4HF2 and KHF2, or a mixture of both.
[0008] Furthermore, in step two, when the inorganic salt is a mixture of NH4HF2 and KHF2, the mixing molar ratio is 1:1 to 1:5.
[0009] Furthermore, the molar ratio of the mixture obtained in step one to the inorganic salt in step two is 1:1 to 1:4.
[0010] Furthermore, in step three, the sintering temperature is 140℃-230℃, and the sintering time is 1-6h.
[0011] Furthermore, in step four, the solvent is any one of H2O2 aqueous solution, H2CO4 aqueous solution, or C6H8O7 aqueous solution.
[0012] Furthermore, in step four, the concentration of the H2O2 aqueous solution is 20%-50% by mass percentage, and the concentrations of the H2CO4 aqueous solution and the C6H8O7 aqueous solution are both 10%-50%.
[0013] The above preparation method can be used to prepare fluoride phosphors that can be efficiently excited by near-ultraviolet and blue light. Regarding the structure of the phosphor, it consists of activator ions Mn... 4+ Doped fluoride A2MF6:Mn 4+ It has a core and is covered with A2MF6.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a method for preparing fluoride phosphors, which can efficiently synthesize A2MF6-coated A2MF6:Mn 4+ Fluoride red phosphors are prepared using a green and environmentally friendly method that does not require the use of toxic HF or HF solutions. The sintering temperature is low, the time is short, and the process is easy to control, making it suitable for large-scale industrial production.
[0015] 2. The fluoride phosphor provided by this invention has excellent optical properties and stability, and its application range is wider. Specifically: (1) In terms of optical properties, a near-ultraviolet excitation peak at about 360 nm and a blue light excitation peak at about 460 nm can be observed in the excitation spectrum, among which the strongest excitation peak is located in the blue light region ( Figure 2 It can be well matched with blue light chips and has a higher luminous intensity compared to existing fluoride phosphors. Figure 3 (2) In terms of stability, the luminescence intensity of the sample gradually decreased with the increase of soaking time. After soaking for 240 minutes, the luminescence intensity was still 53% of the initial intensity, showing good moisture resistance. Figure 5 Furthermore, as the temperature increases, the emission intensity of the sample gradually decreases, reaching 60% of its initial intensity at 150℃, demonstrating good thermal stability. Figure 6 ). Attached Figure Description
[0016] Figure 1 The XRD diffraction pattern and standard data card comparison diagram of the phosphor sample obtained in Example 1 of this invention; Figure 2 The excitation and emission spectra of the phosphor sample obtained in Example 1 of this invention are shown. Figure 3 This is a comparison of the emission spectra of the phosphor sample obtained in Example 1 of the present invention and the phosphor sample obtained in Comparative Example 1. Figure 4 This is a SEM image of the phosphor sample obtained in Example 1 of the present invention; Figure 5 This is a graph showing the change in photoluminescence intensity of the phosphor sample obtained in Example 1 of the present invention over time under water immersion conditions; Figure 6 This is a graph showing the change in photoluminescence intensity of the phosphor sample obtained in Example 1 of the present invention as a function of temperature; Figure 7 The graph shows the performance (color coordinate diagram, emission spectrum) of the phosphor sample obtained in Example 1 of this invention, the commercially available YAG yellow phosphor, and the color conversion LED device packaged with a blue light chip. Figure 8 This is a SEM image of the phosphor sample obtained in Example 2 of the present invention; Figure 9 This is a SEM image of the phosphor sample obtained in Example 3 of the present invention; Figure 10 This is a SEM image of the phosphor sample obtained in Example 4 of the present invention; Figure 11 This is a SEM image of the phosphor sample obtained in Example 5 of the present invention; Figure 12 This is a SEM image of the phosphor sample obtained in Example 6 of the present invention. Detailed Implementation
[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. These embodiments are only for the purpose of helping to understand the present invention and should not be considered as specific limitations of the present invention.
[0018] Example 1: K2TiF6: 20% Mn 4+ Preparation of fluoride red phosphor 0.058 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0447 g of manganese fluoride (MnF2) were weighed out respectively. The raw materials were ground in an agate mortar for 20 min. After grinding until homogeneous, 0.2619 g of ammonium bifluoride (NH4HF2) and 0.1183 g of potassium hydrofluoride (KHF2) were added and ground for another 10 min. After grinding until homogeneous, the mixture was placed in a corundum crucible and sintered on a constant-temperature heating table in a sintering apparatus at 180 ℃ for 4 h. The mixture was then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained. It was then sequentially washed in a 30 wt% citric acid (C6H8O7) solution and anhydrous ethanol, and dried at 70 ℃ for 2 h to obtain the K2TiF6: 20%Mn 4+ Fluoride red fluorescent powder.
[0019] The XRD diffraction pattern of the phosphor is shown in the figure. Figure 1 Excitation and emission spectra are shown below. Figure 2 SEM images can be found Figure 4 The graph showing the change in photoluminescence intensity over time under water immersion conditions is shown below. Figure 5 The graph showing the change in photoluminescence intensity with temperature is shown below. Figure 6 The performance (color coordinate diagram, emission spectrum) data of color conversion LED devices packaged with commercially available YAG yellow phosphor and blue light chips are shown in the figure. Figure 7 .
[0020] from Figure 1 As can be seen, the obtained sample is consistent with the PDF standard card of K2TiF6, indicating that no impurity phase remains. From Figure 2As can be seen in the excitation spectrum, a near-ultraviolet excitation peak at approximately 360 nm and a blue light excitation peak at approximately 460 nm can be observed. The strongest excitation peak is located in the blue light region, which matches well with the blue light chip. The strongest narrowband emission peak is located at 632 nm, a region sensitive to visible light. From... Figure 4 As can be seen, the sample has a regular microstructure, well-developed crystal form, smooth particle surface, and a particle size distribution below 10 μm. Figure 5 It can be seen that the luminescence intensity of the sample gradually decreases with increasing soaking time. After soaking for 240 minutes, the luminescence intensity is still 53% of the initial intensity, indicating good moisture resistance. Figure 6 It can be seen that the emission intensity of the sample gradually decreases with increasing temperature, reaching 60% of its initial intensity at 150℃, indicating good thermal stability. Figure 7 As can be seen, the packaged white LED has a spectrum covering all regions from blue to red, a color rendering index of 88.5, a color temperature of 3647K, and color coordinates of (0.3900, 0.3745), and has the potential for practical applications in display lighting.
[0021] Comparative Example 1: To illustrate the difference between the phosphor described in this invention and existing Mn... 4+ Fluoride-doped phosphor (CN 112094643 B, a type of Mn) 4+ The advantages of doped fluoride narrowband red phosphor in photoluminescence performance were compared between Comparative Example 1 and Example 1.
[0022] Weigh out 0.98g of potassium fluorotitanate (K2TiF6) and 0.02g of potassium fluoromanganate (K2MnF6), respectively, and grind the above raw materials by hand in an agate mortar for 30 minutes to obtain K2TiF6:2%Mn 4+ Fluoride luminescent materials.
[0023] The emission spectra of the samples obtained in Example 1 and Comparative Example 1 of the present invention are compared as follows: Figure 3 As shown. From Figure 3 It can be seen that the ratio of the strongest luminous intensity of the sample obtained in Example 1 of the present invention to that in Comparative Example 1 is 2.52:1, indicating that the present invention has better optical performance.
[0024] Example 2: K2TiF6: 15% Mn 4+ Preparation of fluoride red phosphor 0.0381 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0335 g of manganese fluoride (MnF2) were weighed out and ground in an agate mortar for 20 min. After grinding evenly, 0.0873 g of ammonium bifluoride (NH4HF2) and 0.355 g of potassium hydrofluoride (KHF2) were added and ground for 10 min. After grinding evenly, the mixture was placed in a corundum crucible and sintered on a constant temperature heating table at 180 ℃ for 3 h, and then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained, and then washed successively in a 30 wt% citric acid (C6H8O7) solution and anhydrous ethanol. After drying at 70 ℃ for 2 h, the K2TiF6:15%Mn2 powder was obtained. 4+ Fluoride red fluorescent powder.
[0025] Figure 8 K2TiF6: 15% Mn 4+ The SEM image of the phosphor shows that the phosphor has a uniform particle size.
[0026] Example 3: K2TiF6: 15% Mn 4+ Preparation of fluoride red phosphor 0.0381 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0335 g of manganese fluoride (MnF2) were weighed out respectively. The raw materials were ground in an agate mortar for 20 min. After grinding until homogeneous, 0.2619 g of ammonium bifluoride (NH4HF2) and 0.1183 g of potassium hydrofluoride (KHF2) were added and ground for another 10 min. After grinding until homogeneous, the mixture was placed in a corundum crucible and sintered on a constant-temperature heating table in a sintering device at 160 ℃ for 5 h. The mixture was then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained. It was then washed sequentially in a 30 wt% hydrogen peroxide (H2O2) solution and anhydrous ethanol, and dried at 70 ℃ for 2 h to obtain the K2TiF6: 15%Mn 4+ Fluoride red fluorescent powder.
[0027] Figure 9 K2TiF6: 15% Mn 4+ The SEM image of the phosphor shows that the phosphor has a uniform particle size.
[0028] Example 4: K2TiF6: 13% Mn 4+ Preparation of fluoride red phosphor 0.0255 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0335 g of manganese fluoride (MnF2) were weighed out respectively. These raw materials were ground in an agate mortar for 20 min. After grinding until homogeneous, 0.2328 g of ammonium bifluoride (NH4HF2) and 0.1578 g of potassium hydrofluoride (KHF2) were added and ground for another 10 min. After grinding until homogeneous, the mixture was placed in a corundum crucible and sintered on a constant-temperature heating table in a sintering device at 200 ℃ for 3 h. The mixture was then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained. It was then sequentially washed in a 30 wt% hydrogen peroxide (H2O2) solution and anhydrous ethanol, and dried at 70 ℃ for 2 h to obtain the modified K2TiF6: 13% Mn 4+ Fluoride red fluorescent powder.
[0029] Figure 10 K2TiF6: 13% Mn 4+ The SEM image of the phosphor shows that the phosphor has a uniform particle size.
[0030] Example 5: K2TiF6: 35% Mn 4+ Preparation of fluoride red phosphor 0.0889 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0781 g of manganese fluoride (MnF2) were weighed out respectively. These raw materials were ground in an agate mortar for 20 min. After grinding until homogeneous, 0.1746 g of ammonium bifluoride (NH4HF2) and 0.2367 g of potassium hydrofluoride (KHF2) were added and ground for another 10 min. After grinding until homogeneous, the mixture was placed in a corundum crucible and sintered on a constant-temperature heating table in a sintering device at 200 ℃ for 3 h. The mixture was then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained. It was then sequentially washed in a 40 wt% oxalic acid (H2CO4) solution and anhydrous ethanol, and dried at 70 ℃ for 2 h to obtain the modified K2TiF6: 35% Mn 4+ Fluoride luminescent materials.
[0031] Figure 11 K2TiF6: 35% Mn 4+ The SEM image of the phosphor shows that the phosphor has a uniform particle size.
[0032] Example 6: K2TiF6: 40% Mn 4+ Preparation of fluoride red phosphor 0.1016 g of potassium permanganate (KMnO4), 0.9650 g of potassium fluorotitanate (K2TiF6), and 0.0892 g of manganese fluoride (MnF2) were weighed out respectively. The raw materials were ground in an agate mortar for 20 min. After grinding until homogeneous, 0.2328 g of ammonium bifluoride (NH4HF2) and 0.1578 g of potassium hydrofluoride (KHF2) were added and ground for another 10 min. After grinding until homogeneous, the mixture was placed in a corundum crucible and sintered on a constant-temperature heating table in a sintering device at 180 ℃ for 4 h. The mixture was then cooled to room temperature. The product was thoroughly ground until a uniform fine powder was obtained. It was then sequentially washed in a 40 wt% oxalic acid (H2CO4) solution and anhydrous ethanol, and dried at 70 ℃ for 2 h to obtain the modified K2TiF6:40%Mn. 4+ Fluoride red fluorescent powder.
[0033] Figure 12 K2TiF6: 40% Mn 4+ The SEM image of the phosphor shows that the phosphor has a uniform particle size.
[0034] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing a fluoride phosphor, characterized in that, Includes the following steps: Step 1: Mix and grind A2MF6, KMnO4 and MnF2 thoroughly; wherein, A is selected from one or more of the alkali metals Li, Na, K, Rb or Cs; M is selected from one or more of the alkali metals Ti, Si, Ge, Sn or Zr. Step 2: Add inorganic salts to the mixture obtained in Step 1 and grind thoroughly again; Step 3: Place the mixture obtained in Step 2 into a crucible and transfer it to a sintering device. Set the sintering temperature and sintering time. After sintering, obtain the powder product. Step four: Grind the powder product obtained in step three into a fine powder, place it in a solvent, stir and wash it, and dry it to obtain the fluoride red fluorescent powder.
2. The method for preparing a fluoride phosphor as described in claim 1, characterized in that, In step one, the molar ratio of KMnO4 to MnF2 is 1:3-2:3; the molar ratio of the total amount of KMnO4 and MnF2 to A2MF6 is 0.1:1-0.6:
1.
3. The method for preparing a fluoride phosphor as described in claim 1, characterized in that, In step two, the inorganic salt is one of NH4HF2 and KHF2 or a mixture of both.
4. The method for preparing a fluoride phosphor as described in claim 3, characterized in that, In step two, when the inorganic salt is a mixture of NH4HF2 and KHF2, the mixing molar ratio is 1:1-1:
5.
5. The method for preparing a fluoride phosphor as described in claim 1, characterized in that, The molar ratio of the mixture obtained in step one to the inorganic salt in step two is 1:1 to 1:
4.
6. The method for preparing a fluoride phosphor as described in claim 1, characterized in that, In step three, the sintering temperature is 140℃-230℃ and the sintering time is 1-6h.
7. The method for preparing a fluoride phosphor as described in claim 1, characterized in that, In step four, the solvent is any one of H2O2 aqueous solution, H2CO4 aqueous solution, or C6H8O7 aqueous solution.
8. The method for preparing a fluoride phosphor as described in claim 6, characterized in that, In step four, the concentration of the H2O2 aqueous solution is 20%-50% by mass percentage, and the concentrations of the H2CO4 aqueous solution and the C6H8O7 aqueous solution are both 10%-50%.
9. Fluoride phosphors prepared by any one of the preparation methods described in 1-8.
10. A fluoride phosphor as described in claim 9, characterized in that, The phosphor is composed of activator ions Mn. 4+ Doped fluoride A2MF6:Mn 4+ It has a core and is covered with A2MF6.