A method for preparing a fluoride polycrystalline composite by a template sustained-release in-situ forming

Abstract

This invention discloses a method for preparing polycrystalline fluoride composites through template-based slow-release in-situ molding, belonging to the field of inorganic luminescent functional materials technology. The method includes: providing raw materials, including at least one bulk material as a template, with the raw materials collectively providing A, B, and M ions; mixing the raw materials in a solvent and maintaining the reaction temperature for a specified time, allowing the template to slowly dissolve and release ions; the ions provided by the raw materials react with fluoride ions provided by the solvent and / or the raw materials to grow fluoride crystals in situ on the template surface, with the crystals interpenetrating and fusing to form a polycrystalline composite; after the reaction, the product is obtained by washing and drying. This invention eliminates the need for tableting, high-temperature sintering, and organic binders, and can generate polycrystalline fluorescent fluoride composites of predetermined sizes in a single self-stacking process, avoiding the defects of powder breakage and high-temperature degradation of luminescent ions in traditional two-step methods. It features high luminescence quantum efficiency, a simple process, and ease of industrial production.

Description

Technical Field

[0001] This invention belongs to the fields of inorganic luminescent functional materials, fluorescent ceramics, and polycrystalline molding technology, specifically relating to a method for preparing fluoride polycrystalline composites by template-based slow-release in-situ molding. Background Technology

[0002] Phosphor-converted white light emitting diodes (pc-WLEDs) are currently the most widely used solid-state lighting source due to their advantages such as high energy efficiency, low cost, and long lifespan. These pc-WLEDs are typically assembled by mixing phosphors with epoxy or silicone resins and then coating the mixture onto a GaN blue light chip. However, the low thermal conductivity and poor heat dissipation of organic binders limit the output power and luminous intensity of the devices, making it difficult to meet the demands of high-power lighting.

[0003] To meet the application requirements of high-power WLEDs, highly thermally conductive inorganic ceramic phosphors are gradually replacing powder phosphors in WLEDs. This improves the device's lifespan and stability, which is crucial for high luminous flux applications. Currently, research on ceramic phosphors mainly focuses on yellow-emitting Y3Al5O3. 12 :Ce 3+ (YAG:Ce) 3+ ) and its derivative systems. However, relying solely on YAG:Ce 3+ Ceramic WLEDs lack red light components, and their color rendering index (CRI) and correlated color temperature (CCT) are insufficient to meet the requirements of high-quality lighting. Therefore, there is an urgent need to develop red phosphors suitable for high-power LEDs with high color rendering and low color temperature.

[0004] Fluoride red fluorescent materials can significantly improve the luminescence performance of pc-WLEDs, achieving warm white light emission. Mn... 4+ When Mn is used as a dopant ion in the fluoride matrix 4+ It exhibits a broad excitation band in the blue light region (approximately 450nm) and a narrow emission band in the red light region (approximately 630nm), which highly matches the requirements of pc-WLED and can significantly improve its performance. Currently, Mn 4+ Activated fluoride red fluorescent materials have been widely studied and reported mainly in powder form, while research on bulk morphology (i.e. fluoride fluorescent ceramics) still faces challenges, as existing preparation methods are difficult to obtain high-performance fluorescent ceramic materials.

[0005] Researchers have attempted a two-step method to prepare fluoride fluorescent ceramics: first, fluoride fluorescent powder is synthesized using liquid-phase methods (co-precipitation, etching, hydrothermal methods, ion exchange, etc.), and then the powder is densified in a mold using traditional cold pressing or hot pressing methods. For example, Li et al. prepared KLiSnF6:Mn using an ion exchange method. 4+ Phosphors were then used to prepare translucent ceramic sheets via cold pressing and sintering (Ceramic International, 2023, 49(23): 39499-39505). Ren et al. prepared Rb2GeF6:Mn using a co-precipitation method. 4+ and K2GeF6:Mn 4+ Two phosphors were used, and two ceramic phosphor sheets were subsequently prepared by hot pressing and sintering (Journal of the American Ceramic Society, 2025, 108:e20674). RA Osborne et al. used K2SiF6:Mn 4+ Phosphor powder was placed in a steel mold under argon protection, pressurized at 172 MPa in a vacuum, and heated to 500℃ for 1 hour to obtain a transparent ceramic sheet (Optical Materials, 2020, 107:110140). Patent CN119080497A uses a hydrothermal method to synthesize nanoscale fluoride powder, which is then hot-pressed to form (K... 0.99-x Li x )2(SiM)F6:Mn 4+ (Where M = Ge or Ti) Transparent fluorescent ceramic.

[0006] However, the above two-step preparation strategy has the following drawbacks: First, the process is cumbersome, requiring powder synthesis before sintering, which increases production costs and time. Second, during sintering, the polycrystalline powder breaks down and pulverizes under pressure, generating numerous defects. Light repeatedly refracts and reabsorbs at these defects, leading to a decrease in quantum efficiency. Furthermore, the manganese outer shell contains multiple valence electrons, allowing it to exhibit various valence states. Heating (typically requiring hundreds of degrees Celsius) easily causes Mn to... 4+ The conversion of fluorescent ions to other valence states severely impairs their luminescence performance. Therefore, the existing two-step method cannot fundamentally avoid the decrease in luminescence quantum efficiency, preventing the industrial-scale production and application of fluoride red fluorescent ceramics. Summary of the Invention

[0007] This invention addresses the problems of existing traditional two-step methods (liquid-phase powder preparation + cold pressing or hot pressing sintering to prepare bulk materials), which are not only cumbersome in process but also difficult to produce high quantum efficiency fluoride red phosphor ceramics. Furthermore, these methods cannot overcome the defects caused by pressure during preparation and the degradation of luminescent ions due to high temperatures, hindering industrial application. This invention provides a template-based slow-release in-situ molding method for preparing polycrystalline fluoride composites. This method eliminates the need for pelletizing, high-temperature sintering, and organic binders, and can generate polycrystalline fluoride phosphors of predetermined sizes in a single self-stacking process. These phosphors can be directly used in optical functional devices such as high color rendering index WLEDs and high-power laser lighting.

[0008] To achieve the above objectives, the specific solution adopted by the present invention is as follows: A method for preparing fluoride polycrystalline complexes by template-based slow-release in-situ molding, wherein the general chemical formula of the fluoride polycrystalline complex is A2(B 1-x M x )F6 or A(B 1-x M x F6, where: When the general formula is A2(B) 1-x M x When F6 is present, A is NH4. + Li + Na + K + 、Rb + Cs + At least one of them; When the general formula is A(B) 1-x M x When F6, A is Ba 2+ Ca 2+ Mg 2+ 、Sr 2+ At least one of them; B is Si 4+ 、Ge 4+ Ti 4+ Sn 4+ Zr 4+ Hf 4+ At least one of them; M is Mn 4+ Cr 3+ Eu 3+ Yb 3+ At least one of them; And 0 <x<1.0; Includes the following steps: Step (1): Provide raw materials, wherein the raw materials contain at least one block as a template, and the raw materials provide at least A ions, B ions and M ions together; Step (2): Mix the raw materials in a solvent and maintain the reaction time at the reaction temperature to allow the template to slowly dissolve and release ions. The A, B and M ions provided by the raw materials react together with the fluoride ions provided by the solvent and / or the raw materials to grow fluoride crystals in situ on the surface of the template. The fluoride crystals interpenetrate and fuse to form a polycrystalline composite. Step (3): After the reaction is complete, remove the solvent, wash and dry to obtain the fluoride polycrystalline composite.

[0009] Furthermore, the raw materials collectively provide A ions, B ions, M ions and fluoride ions, and the raw materials are fluorides capable of simultaneously providing A ions, B ions and M ions.

[0010] Furthermore, the solvent is hydrofluoric acid with a mass concentration of 5% to 70%.

[0011] Furthermore, the reaction temperature is -40℃ to 40℃, and the reaction time is 0.01 days to 20 days.

[0012] Further, in step (1), the template comprises a block containing B ions and powder capable of providing A ions and M ions; in step (2), the powder is mixed in a solvent, and then the template is placed therein, and the reaction time is maintained at the reaction temperature.

[0013] Furthermore, the template is an elemental substance or a compound containing at least one of Si, Ge, Sn, Zr, and Ti, and its form is single crystal, polycrystalline, ceramic, or glass.

[0014] Furthermore, in the general chemical formula of the fluoride polycrystalline complex, A is Na. + or K + B is Si 4+ Or Ge 4+ M is Mn 4+ or Cr 3+ .

[0015] Furthermore, the template is a single crystal of silicon dioxide, quartz glass, or germanium dioxide glass.

[0016] Furthermore, the M ions are provided by K2MnF6, Na2MnF6, K3CrF6 or Na3CrF6.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: (1) The traditional two-step method requires first synthesizing powder in liquid phase and then cold pressing or hot pressing sintering, which is complicated, time-consuming and energy-intensive. The present invention places the template directly in the reaction system and forms the product in one step by slow release in situ growth through the template. It does not require separate powder synthesis, tableting and high-temperature sintering, or the addition of organic binders, which significantly simplifies the process, reduces production costs and makes it easy to achieve industrial-scale production.

[0018] (2) In the traditional sintering process, polycrystalline powder breaks and pulverizes under pressure, generating a large number of defects. Light is repeatedly refracted and reabsorbed at the defects, resulting in a serious decrease in quantum efficiency. The present invention adopts a template slow-release in-situ growth method, in which crystals grow naturally on the template surface and interpenetrate and fuse with each other. No external pressure is applied throughout the process, avoiding powder breakage and defect generation, and growing a bulk fluorescent composite material with perfect crystallization and very few defects, thereby maintaining a high luminescence quantum efficiency.

[0019] (3) Manganese has multiple valence electrons in its outer shell, which can easily lead to Mn valence electron depletion at high temperatures. 4+ Restored to other valence states (such as Mn) 2+ Mn 3+ This results in the loss of luminescence ability; traditional hot-pressing sintering methods typically require temperatures of several hundred degrees Celsius, which easily leads to the degradation of luminescent ions; the reaction process of this invention is carried out entirely at low temperatures (-40℃ to 40℃), requiring no heating, effectively avoiding the damage of high temperatures to Mn. 4 + Cr 3+ The destruction of the valence state of doped ions ensures the activity of luminescent ions and improves luminescence performance.

[0020] (4) The bulk materials prepared by traditional methods need to be cut and polished to obtain a specific shape, which not only increases the process but also wastes materials. The present invention uses a bulk material of a specific shape and size as a template, and the product grows in situ on the template surface. The resulting polycrystalline composite has the same macroscopic geometry and size as the template, and phosphors of the required shape and size can be obtained directly without secondary processing.

[0021] (5) The fluoride polycrystalline fluorescent composite prepared by the present invention has excellent luminescence performance and controllable shape and size. It can be directly used in optical functional devices such as high color rendering index WLED, high power laser lighting, and liquid crystal display backlight. It solves the technical problem that existing fluoride red fluorescent ceramics are difficult to industrialize and apply, and has broad industrialization prospects. Attached Figure Description

[0022] Figure 1 A schematic diagram of in-situ integral molding preparation of fluoride polycrystalline composites using a template-based sustained-release method.

[0023] Figure 2The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite cell in Example 1 is shown.

[0024] Figure 3 This is a photograph of the original SiO2 crystal pillar from Example 1.

[0025] Figure 4 This is a photograph of the polycrystalline fluorescent composite cell obtained in Example 1.

[0026] Figure 5 This is a photograph of the polycrystalline fluorescent composite cell obtained in Example 1 under 365nm ultraviolet light excitation.

[0027] Figure 6 The PL spectrum of the polycrystalline fluorescent composite cell obtained in Example 1 under 365nm ultraviolet light excitation.

[0028] Figure 7 The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite square sheet in Example 2 is shown.

[0029] Figure 8 This is a photograph of the original quartz glass sheet from Example 2.

[0030] Figure 9 This is a photograph of the polycrystalline fluorescent composite sheet obtained in Example 2.

[0031] Figure 10 The image shows the polycrystalline fluorescent composite sheet obtained in Example 2 under 365nm ultraviolet light excitation.

[0032] Figure 11 The PL spectrum of the polycrystalline fluorescent composite sheet obtained in Example 2 under 365nm ultraviolet light excitation.

[0033] Figure 12 The XRD pattern is shown in Example 3, which is the powder obtained by grinding the polycrystalline fluorescent composite disc.

[0034] Figure 13 This is a photograph of the original quartz glass disc from Example 3.

[0035] Figure 14 This is a photograph of the polycrystalline fluorescent composite disc obtained in Example 3.

[0036] Figure 15 This is a photograph of the polycrystalline fluorescent composite disc obtained in Example 3 under 365nm ultraviolet light excitation.

[0037] Figure 16 The photoluminescence (PL) spectrum of the polycrystalline fluorescent composite disc obtained in Example 3 under 365 nm ultraviolet light excitation.

[0038] Figure 17The XRD pattern is shown in Example 4, which is the powder obtained by grinding the polycrystalline fluorescent composite disc.

[0039] Figure 18 This is a photograph of the original quartz glass disc from Example 4.

[0040] Figure 19 This is a photograph of the polycrystalline fluorescent composite disc obtained in Example 4.

[0041] Figure 20 This is a photograph of the polycrystalline fluorescent composite disc obtained in Example 4 under 365nm ultraviolet light excitation.

[0042] Figure 21 The PL spectrum of the polycrystalline fluorescent composite disc obtained in Example 4 under 365nm ultraviolet light excitation. Detailed Implementation

[0043] This invention provides a method for preparing polycrystalline fluoride composites using a template-based slow-release in-situ molding process. The method utilizes the slow dissolution of a template (single crystal, polycrystalline, ceramic, or glass) in a solvent. The template slowly dissolves in the solvent, releasing ions that react with other ions provided by the raw materials (if present) and fluoride ions in the solvent to form fluoride crystals on the template surface. As the template gradually dissolves, the crystals continuously grow and interpenetrate on the template surface, eventually forming a polycrystalline bulk. The macroscopic geometry and dimensions of this bulk are substantially consistent with the template. This method is not limited to specific solvents, raw materials, or templates.

[0044] The fluoride polycrystalline complex of the present invention is of the general chemical formula A2(B 1-x M x )F6 or A(B 1-x M x F6 represents this. Where the general formula is A2(B 1-x M x When F6 is present, A is NH4. + Li + Na + K + 、Rb + Cs + At least one of them; When the general formula is A(B) 1-x M x When F6, A is Ba 2+ Ca 2+ Mg 2+ 、Sr 2+ At least one of them; B is Si 4+ 、Ge 4+ Ti 4+ Sn 4+ Zr4+ Hf 4+ At least one of them; M is Mn 4+ Cr 3+ Eu 3+ Yb 3+ At least one of them; And 0 <x<1.0。

[0045] The specific preparation method of the above-mentioned fluoride polycrystalline complex is described in detail below.

[0046] Step (1) Provide raw materials According to the stoichiometric ratio, weigh the raw material compound containing A ions, B ions, and dopant M ions. The raw material contains at least one bulk component as a template. Depending on the different combinations of raw materials, the following situations can be identified: (1-1) When the template contains only B ions, the raw material also needs to provide powder that can provide A and M ions, and the powder and template are used together as raw materials. For example, SiO2 crystal pillars or quartz glass sheets are used as templates (providing B ions and SiO2 crystals). 4 + A ions (Na+) are provided by NaF or KF powder. + or K + K2MnF6 powder provides M ions (Mn 4+ ); (1-2) When the template contains only A ions, the raw material also needs to provide powder that can provide B ions and M ions, and the powder and the template are used together as raw materials; (1-3) When the template contains both B ions and A ions, the raw material also needs to provide powder that can provide M ions, and, if necessary, powder that can provide A ions. (1-4) When the template contains both B ions and M ions, the raw material also needs to provide powder that can provide A ions; (1-5) When the template contains both A ions and M ions, the raw material also needs to provide powder that can provide B ions; (1-6) When the template contains A ions, B ions and M ions at the same time, the raw material can use only the template and no other raw materials are required.

[0047] It should be noted that the above are some common raw material combinations, but the raw material combination of the present invention is not limited to these. As long as the raw material contains at least one block as a template, and the raw material can jointly provide A ions, B ions and M ions, and the product is prepared by template slow-release in-situ molding method, it falls within the protection scope of the present invention.

[0048] The template is a bulk material that dissolves slowly in the reaction solvent, gradually providing its own ions for crystal growth. Its surface also serves as the growth site for the crystals. The macroscopic geometry and size of the template determine the macroscopic geometry and size of the final product. The roles of each raw material are as follows: the bulk template serves as both an ion source and a crystal growth site; its slow dissolution ensures the stability of the crystal growth process. Powdered or other raw materials provide the ions lacking in the template. The solvent provides fluoride ions and reacts with other ions to form fluoride crystals.

[0049] Step (2) Template-released in-situ growth The raw materials are mixed with a solvent, and the reaction is maintained at the reaction temperature for a specified time, allowing the template to slowly dissolve and release ions. The ions provided by the raw materials react with fluoride ions provided by the solvent and / or the raw materials, resulting in the in-situ growth of fluoride crystals on the template surface. As the reaction proceeds, the crystals continuously grow, interpenetrate, and fuse, ultimately forming a polycrystalline composite. The principle of this step is that the template slowly dissolves in the solvent, continuously releasing its contained ions, avoiding uneven nucleation caused by excessively high ion concentrations. Simultaneously, ions provided by other raw materials are uniformly dispersed in the reaction system, participating in the reaction together with fluoride ions provided by the solvent and / or the raw materials. Due to the low interfacial energy of the template surface, crystals preferentially nucleate and grow on the template surface. As the template continues to dissolve, crystals grow outwards on the template surface, adjacent crystals contact and interpenetrate, ultimately forming a complete block, whose macroscopic geometry and dimensions are essentially the same as the template. In this step, the reaction temperature range is -40℃ to 40℃. The lower temperature helps to control the dissolution rate of the template and makes the crystal growth more uniform. The reaction time range is 0.01 days to 20 days. The longer reaction time ensures that the crystals grow and fuse fully.

[0050] The solvent is preferably hydrofluoric acid. It should be noted that hydrofluoric acid can be used as the solvent regardless of whether the raw material itself can provide fluoride ions; that is, hydrofluoric acid can be used as a supplementary source of fluoride ions or as the sole source of fluoride ions.

[0051] Step (3), Post-processing After the reaction is complete, the supernatant is removed, and the mixture is rinsed with a cleaning agent to remove residual solvent and unreacted raw materials. After drying, the polycrystalline fluoride composite is obtained.

[0052] Example 1: Preparation of Na2(Si) using a quartz crystal column template 1-x Mn x F6 polycrystalline fluorescent composite cell (1) Material preparation: Weigh 2.002 g of NaF (Aladdin, ≥99.99%) and 0.1006 g of K2MnF6 (laboratory-made), place them in a plastic petri dish (φ120 mm), add 100 mL of hydrofluoric acid (Aladdin, GR, ≥40%) to obtain a mixed solution. Then add a SiO2 crystal column (Aladdin, ≥99.99%, φ2 mm × 10 mm, such as...) Figure 3 (As shown) 5.1 g. After standing at room temperature for 21 h, the supernatant was removed, and the sample was washed twice each with glacial acetic acid and anhydrous ethanol. It was then dried at 30°C for 2 h to obtain Na₂(Si)₂ with x ≈ 0.0048 (i.e., Mn doping content approximately 0.48%). 1-x Mn x F6 polycrystalline fluorescent composite cell; (2) Material characterization: Figure 2 The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite cell in this embodiment matches PDF#96-901-1059, confirming that its main crystalline phase is Na2SiF6. Figure 3 These are physical photos of the original SiO2 crystal pillars, showing a total of ten pillars. Figure 4 The following is a photograph of the polycrystalline fluorescent composite cell obtained in this embodiment. A total of ten composite cells are shown. The left side of the image shows the groove facing upwards, and the right side shows the groove facing downwards. The black line on the graph paper can be clearly observed at the bottom of the groove on the left, indicating that it has good light transmittance. Figure 5 The image shows a polycrystalline fluorescent composite cell obtained in this embodiment under 365nm ultraviolet light excitation, which can be seen to emit bright red light throughout. Figure 6 The PL spectrum of the polycrystalline fluorescent composite cell obtained in this embodiment under 365nm ultraviolet light excitation is Mn. 4+ Activated fluorides exhibit typical discrete narrowband sharp-line emission spectra.

[0053] Example 2: Preparation of Na2(Si) using a quartz glass square template 1-x Mn x F6 polycrystalline fluorescent composite sheet (1) Material preparation: Weigh 0.401 g of NaF (Aladdin, ≥99.99%) and 0.021 g of K2MnF6 (laboratory-made), place them in a plastic petri dish (φ70 mm), add 20 mL of hydrofluoric acid (Aladdin, GR, ≥40%) to obtain a mixed solution. Then add a quartz glass square (15 mm × 15 mm × 2 mm, such as...) Figure 8 One sample (net weight approximately 0.95 g) was placed at room temperature for 25 h, the supernatant was removed, and the sample was washed twice each with glacial acetic acid and anhydrous ethanol. The sample was then dried at 30°C for 2 h to obtain Na₂(Si)₂ with x ≈ 0.0053 (i.e., Mn doping content approximately 0.53%). 1-x Mn xF6 polycrystalline fluorescent composite wafer; (2) Material characterization: Figure 7 The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite square sheet in this embodiment matches PDF#96-901-1059, confirming that its main crystalline phase is Na2SiF6. Figure 8 This is a photograph of the original square of quartz glass. Figure 9 The photograph shows the actual polycrystalline fluorescent composite sheet obtained in this embodiment. It can be seen that it perfectly inherits the size of the original quartz sheet, which is a regular sheet of 15mm×15mm. Figure 10 The image shows the polycrystalline fluorescent composite sheet obtained in this embodiment under 365nm ultraviolet light excitation, which can be seen to emit bright red light throughout. Figure 11 The PL spectrum of the polycrystalline fluorescent composite sheet obtained in this embodiment under 365nm ultraviolet light excitation is Mn. 4+ Activated fluorides exhibit typical discrete narrowband sharp-line emission spectra.

[0054] Example 3: Preparation of Na2(Si) using a quartz glass disc template 1-x Mn x F6 polycrystalline fluorescent composite disc (1) Material preparation: Weigh 0.163 g of NaF (Aladdin, ≥99.99%) and 0.008 g of K2MnF6 (laboratory-made), place them in a plastic petri dish (φ35 mm), add 8 mL of hydrofluoric acid (Aladdin, GR, ≥40%) to obtain a mixed solution. Then add a quartz glass disc (φ10 mm × 2 mm, such as...) Figure 13 One sample (net weight approximately 0.4 g) was placed at room temperature (25°C) for 22 h, the supernatant was removed, and the sample was washed twice each with glacial acetic acid and anhydrous ethanol. The sample was then dried at 30°C for 2 h to obtain Na₂(Si)₂ with x ≈ 0.0048 (i.e., Mn doping content approximately 0.48%). 1-x Mn x F6 polycrystalline fluorescent composite disc; (2) Material characterization: Figure 12 The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite disc in this embodiment matches PDF#96-901-1059, confirming that its main crystalline phase is Na2SiF6. Figure 13 This is a photograph of the original quartz glass disc. Figure 14 The photograph shows the actual polycrystalline fluorescent composite disc obtained in this embodiment. It can be seen that it perfectly inherits the size of the original quartz disc, which is a regular disc with a diameter of φ10mm. The black lines on the graph paper can be clearly observed, indicating that it has good light transmittance. Figure 15The image shows the polycrystalline fluorescent composite disc obtained in this embodiment under 365nm ultraviolet light excitation. It can be seen that it emits bright red light throughout, and the black lines on the graph paper further illustrate its excellent light transmittance. Figure 16 The PL spectrum of the polycrystalline fluorescent composite disc obtained in this embodiment under 365nm ultraviolet light excitation is Mn. 4+ Activated fluorides exhibit typical discrete narrowband sharp-line emission spectra.

[0055] Example 4: Preparation of K2(Si) using a quartz glass disc template 1-x Mn x F6 polycrystalline fluorescent composite disc (1) Material preparation: Weigh 0.241 g of KF (Aladdin, ≥99.9%) and 0.008 g of K2MnF6 (laboratory-made), place them in a plastic petri dish (φ35 mm), add 8 mL of hydrofluoric acid (Aladdin, GR, ≥40%) to obtain a mixed solution. Then add a quartz glass disc (φ10 mm × 2 mm, such as...) Figure 18 One sample (net weight approximately 0.4 g) was placed at room temperature (25°C) for 22 h, the supernatant was removed, and the sample was washed twice each with glacial acetic acid and anhydrous ethanol. The sample was then dried at 30°C for 2 h to obtain K2(Si) with x ≈ 0.0048 (i.e., Mn doping content approximately 0.48%). 1-x Mn x F6 polycrystalline fluorescent composite disc; (2) Material characterization: Figure 17 The XRD pattern of the powder obtained by grinding the polycrystalline fluorescent composite wafer in this embodiment matches PDF#96-901-1293, confirming that its main crystalline phase is K2SiF6. Figure 18 This is a photograph of the original quartz glass disc. Figure 19 The photograph shows the actual polycrystalline fluorescent composite disc obtained in this embodiment. It is light yellow and inherits the size of the original quartz disc, which is a regular disc with a diameter of φ10mm. Its surface is covered with a large number of regular crystal particles. Figure 20 The image shows the polycrystalline fluorescent composite disc obtained in this embodiment under 365nm ultraviolet light excitation. It can be seen that it emits bright red light throughout and a large number of regular crystal particles can be observed. Figure 21 The PL spectrum of the polycrystalline fluorescent composite disc obtained in this embodiment under 365nm ultraviolet light excitation is Mn. 4+ Activated fluorides exhibit typical discrete narrowband sharp-line emission spectra.

[0056] In summary, Examples 1-4 used quartz crystal pillars, quartz glass squares, and quartz glass discs as templates, respectively, with NaF or KF as the A ion source and K2MnF6 as the Mn ion source. 4+ Na2(Si) was prepared in situ using an ion source in hydrofluoric acid solvent via a template-based slow-release in-situ molding method.1-x Mn x F6 and K2(Si) 1-x Mn x F6 polycrystalline fluorescent complex. All examples demonstrate that it contains B ions (Si). 4+ The bulk template slowly dissolves in hydrofluoric acid solvent, continuously releasing B ions. Simultaneously, A and M ions provided by the powder react with fluoride ions in the solvent, resulting in the in-situ growth of fluoride crystals on the template surface. These crystals interpenetrate and fuse to form a polycrystalline composite, which possesses a macroscopic geometry and size essentially identical to the template. XRD characterization confirms that the main crystalline phase of the obtained product is the target fluoride, and PL spectroscopy shows that the product exhibits Mnn... 4+ The activation of the typical discrete narrow-band sharp-line red light emission of fluorides proves that the method of the present invention successfully prepared high-quality polycrystalline fluorescent fluoride complexes.

[0057] The template-based slow-release in-situ molding method provided by this invention eliminates the need for tableting, high-temperature sintering, and organic binders. It can generate polycrystalline fluoride phosphors of predetermined sizes in one step through self-deposition, which can be directly used in optical functional devices such as high color rendering index WLEDs and high-power laser lighting. This method effectively overcomes the defects of powder crushing under pressure and high temperature leading to degradation of luminescent ions in the traditional two-step method, and has significant prospects for industrial application.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the 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 polycrystalline composite by template-based slow-release in-situ molding, wherein the general chemical formula of the fluoride polycrystalline composite is A2(B 1-x M x )F6 or A(B 1-x M x F6, where: When the general formula is A2(B) 1-x M x When F6 is present, A is NH4. + Li + Na + K + 、Rb + Cs + At least one of them; When the general formula is A(B) 1-x M x When F6, A is Ba 2+ Ca 2+ Mg 2+ 、Sr 2+ At least one of them; B is Si 4+ 、Ge 4+ Ti 4+ Sn 4+ Zr 4+ Hf 4+ At least one of them; M is Mn 4+ Cr 3+ Eu 3+ Yb 3+ At least one of them; And 0 <x<1.0; Its characteristic is that it includes the following steps: Step (1): Provide raw materials, wherein the raw materials contain at least one block as a template, and the raw materials provide at least A ions, B ions and M ions together; Step (2): Mix the raw materials in a solvent and maintain the reaction time at the reaction temperature to allow the template to slowly dissolve and release ions. The A, B and M ions provided by the raw materials react together with the fluoride ions provided by the solvent and / or the raw materials to grow fluoride crystals in situ on the surface of the template. The fluoride crystals interpenetrate and fuse to form a polycrystalline composite. Step (3): After the reaction is complete, remove the solvent, wash and dry to obtain the fluoride polycrystalline composite.

2. The method according to claim 1, characterized in that, The raw materials collectively provide A ions, B ions, M ions and fluoride ions, and the raw materials are fluorides that can simultaneously provide A ions, B ions and M ions.

3. The method according to claim 1 or 2, characterized in that, The solvent used is hydrofluoric acid, with a mass concentration of 5% to 70%.

4. The method according to claim 1, characterized in that, The reaction temperature is -40℃ to 40℃, and the reaction time is 0.01 days to 20 days.

5. The method according to claim 1, characterized in that, In step (1), the template comprises a block containing B ions and powder capable of providing A and M ions; in step (2), the powder is mixed in a solvent, and then the template is placed therein, and the reaction time is maintained at the reaction temperature.

6. The method according to claim 5, characterized in that, The template is an element or compound containing at least one of Si, Ge, Sn, Zr, and Ti, and its form is single crystal, polycrystalline, ceramic, or glass.

7. The method according to claim 5, characterized in that, In the general chemical formula of the fluoride polycrystalline complex, A is Na. + or K + B is Si 4+ Or Ge 4+ M is Mn 4+ or Cr 3+ .

8. The method according to claim 5, characterized in that, The template is a single crystal of silicon dioxide, quartz glass, or germanium dioxide glass.

9. The method according to claim 5, characterized in that, The M ions are provided by K2MnF6, Na2MnF6, K3CrF6 or Na3CrF6.

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