Preparation of cr 3+-doped fluorescent material and use thereof in plant light supplement lamp

Abstract

The present invention relates to the technical field of the preparation of Cr3+-doped fluorescent materials. Disclosed are the preparation of a Cr3+-doped fluorescent material and the use thereof in a plant light supplement lamp. The preparation comprises the following steps: weighing a matrix raw material and a Cr3+-containing raw material according to the stoichiometric ratio, and respectively grinding and then storing same in a dryer; placing the raw materials into a ball milling tank, and subjecting same to planetary ball milling for 3-6 hours; transferring same to an alumina crucible, and pre-sintering same for 2-5 hours; after secondary ball milling, adding a fluxing agent thereto; placing same in a high-temperature furnace and sintering same for 6-10 hours, and furnace cooling same or cooling same under the protection of an inert gas; and firstly coarsely crushing same, then grinding same to 10-30 μm, alternately cleaning same with deionized water and ethanol, drying same in an air dry oven, detecting and screening the product by using a fluorescence spectrophotometer, an X-ray diffractometer and a scanning electron microscope, and remanufacturing unqualified products after adjusting process parameters according to detection results. The present invention has a high light-emitting efficiency, and the spectrum thereof is suitable for plant photosynthetic absorption. When being applied to a light-supplementing lamp, plant growth can be promoted, the plant height and the chlorophyll content are significantly increased, and the natural spectrum is simulated, such that the material is suitable for multiple cultivation scenarios.

Description

Cr 3+ Preparation of doped fluorescent materials and their application in plant grow lights Technical Field

[0001] This invention relates to Cr 3+ The field of preparation technology for doped fluorescent materials, specifically Cr 3+ Preparation of doped fluorescent materials and their application in plant grow lights. Background Technology

[0002] With the continuous development of modern agricultural technology, plant supplemental lighting technology is playing an increasingly important role in fields such as facility agriculture, plant factories, and indoor horticulture. Plant growth is inseparable from light, and different wavelengths of light have different effects on plant photosynthesis, morphogenesis, and physiological metabolism.

[0003] In the natural environment, sunlight is the primary light source for plant growth, and its spectrum covers a wide range from ultraviolet to infrared. However, in certain growing environments, such as greenhouses during winter or rainy days, natural light is insufficient; plant factories rely entirely on artificial light sources due to a lack of natural lighting; and when cultivating ornamental plants indoors, the intensity and spectrum of indoor light often fail to meet the plants' needs. Therefore, artificial plant grow lights have emerged.

[0004] Traditional plant grow lights mainly include incandescent lamps, fluorescent lamps, and high-pressure sodium lamps. Incandescent lamps have low luminous efficiency, converting most of their electrical energy into heat rather than light. Furthermore, their spectrum contains a large infrared component and relatively little visible light, making them not only energy-wasting but also having limited effect on plant growth when used for supplemental lighting. While fluorescent lamps improve luminous efficiency to some extent, the light conversion efficiency of the phosphor still needs improvement, and their spectral distribution does not perfectly match the absorption spectrum of plant photosynthesis, failing to fully meet the plant's need for specific wavelengths of light. High-pressure sodium lamps primarily emit orange-yellow light with a high red component, but lack other beneficial light components such as blue light, leading to problems like excessive vegetative growth and weak stems with long-term use.

[0005] In recent years, LED plant grow lights have gained widespread attention and application due to their advantages such as energy saving, long lifespan, and adjustable spectrum. However, current LED plant grow lights still have some shortcomings in spectral design. For example, a simple combination of blue or red LEDs cannot accurately simulate the spectral characteristics of natural sunlight, and cannot fully meet the complex requirements of plants for light quality and intensity at different growth stages. Moreover, some existing fluorescent materials used in plant grow lights have defects in luminous efficiency, spectral purity, and compatibility with the chip.

[0006] Cr 3+Doped fluorescent materials possess unique optical properties; when excited by specific wavelengths of light, they can emit red light that matches the absorption spectrum of plant photosynthesis. Developing Cr... 3+ Doped fluorescent materials and their application in plant grow lights are expected to overcome the shortcomings of traditional plant grow lights and existing fluorescent materials. Through rational design and optimized preparation processes, efficient and precise plant lighting can be achieved, improving plant growth quality and yield, meeting the growing demand of modern agriculture for plant lighting technology, and promoting the further development of facility agriculture and plant factories. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the shortcomings of existing technologies, this invention provides a method for preparing Cr3+-doped fluorescent materials and their application in plant grow lights.

[0009] (II) Technical Solution

[0010] A type of Cr 3+ A method for preparing doped fluorescent materials includes the following steps:

[0011] S1: Raw material weighing and pretreatment. Weigh the matrix raw material and Cr-containing raw material. 3+ The raw materials, including the matrix, are oxides, carbonates, nitrates, and halides of alkali metals or alkaline earth metals, containing Cr. 3+ The raw materials are chromium oxide, nitrate, and acetate. Each raw material is ground to a particle size of 5-20 μm, and then dried in an oven at 50-70℃ for 3-6 hours to remove moisture and impurities. Each raw material is stored in a desiccator to prevent deliquescence.

[0012] S2: Initial mixing. Place the processed raw materials in a ball mill jar (made of stainless steel or ceramic, with zirconia balls or agate balls as the milling media, and a ball-to-material ratio of 4:1-8:1), and mill them in a planetary ball mill for 3-6 hours at a speed of 300-500 rpm to ensure that the raw materials are initially mixed evenly.

[0013] S3: Pre-sintering. The ball-milled mixed raw materials are transferred to an alumina crucible and placed in a high-temperature furnace for pre-sintering at 800-1000℃ for 2-5 hours. The sintering atmosphere is air or nitrogen, and the heating rate is 3-8℃ / minute. Pre-sintering can initially stabilize the structure of the raw materials and remove some volatiles.

[0014] S4: Secondary mixing and addition of flux. Ball mill the pre-sintered material again for 2-4 hours (under the same conditions as the initial mixing). Then add flux (such as ammonium fluoride, boric acid or sodium fluoride) at 2-8% of the total mass of raw materials and continue ball milling for 1-2 hours to ensure uniform dispersion of flux.

[0015] S5: High-temperature sintering doping. The material after secondary mixing is placed back into a high-temperature furnace and sintered at 1000-1400℃ for 6-10 hours to achieve Cr doping. 3+ Doping is incorporated into the matrix lattice, and the sintering atmosphere is nitrogen or an inert gas (such as argon). The heating rate is 5-10℃ / min, and the cooling is achieved by furnace cooling or cooling at a rate of 3-8℃ / min under inert gas protection.

[0016] S6: Post-processing. The sintered material is first coarsely crushed by a jaw crusher, then ground to a particle size of 10-30 μm by a planetary ball mill. It is then washed alternately with deionized water and ethanol 3-5 times, and finally dried in a forced-air drying oven at 80-100℃ for 3-5 hours to obtain Cr. 3+ Doped fluorescent materials.

[0017] S7: Performance testing and screening. Fluorescence spectrometer is used to detect the emission spectrum of fluorescent materials under ultraviolet or blue light excitation to ensure that the peak wavelength is between 600-800nm. At the same time, the crystal structure of the material (using X-ray diffraction) and grain size (using scanning electron microscopy) are detected to screen out products that meet the requirements. Unqualified products are returned for reprocessing.

[0018] Furthermore, in step S1, the grinding equipment is a vibratory mill or an air jet mill, which can more efficiently control the particle size of the raw material within the required range, and the drying process is carried out in a vacuum environment with a vacuum degree of 0.02-0.08 MPa, which can further reduce impurity residue.

[0019] In step S2, the ball mill is equipped with a cooling system (such as a water-cooled jacket or an air-cooled device) to prevent changes in the properties of the raw materials due to frictional heat during the ball milling process. The ball mill jar must be cleaned with acetone or ethanol and dried before use.

[0020] Furthermore, in step S3, the furnace chamber of the high-temperature furnace is made of high-purity alumina or mullite material, which has good high-temperature resistance and heat insulation performance, and is equipped with an automatic temperature control system that can control temperature fluctuations within ±3℃, while also monitoring the oxygen or nitrogen content of the atmosphere inside the furnace in real time (accuracy of ±0.1%).

[0021] In step S4, the flux needs to be ground to a particle size of 1-5 μm and passed through a 200-400 mesh sieve before being added to ensure better uniform dispersion.

[0022] Furthermore, in step S5, the heating element of the high-temperature furnace is a silicon carbide rod or a silicon molybdenum rod, which can heat up quickly and have a uniform temperature distribution. During the sintering process, the pressure inside the furnace can be monitored by a pressure sensor (accuracy of ±0.05MPa), and the sintering process parameters can be adjusted according to the pressure changes.

[0023] In step S6, key components of the crusher and ball mill (such as crushing tooth plates, inner walls of the ball mill jar, etc.) are made of wear-resistant materials (such as hard alloy or ceramic coating) to extend the service life of the equipment. Ultrasonic assisted washing is used for 10-20 minutes (ultrasonic frequency 20-40kHz) during the washing process to improve the washing effect.

[0024] Furthermore, in step S7, the excitation source of the fluorescence spectrometer is a xenon lamp or a mercury lamp with a spectral resolution of 0.1-1 nm, the scanning step size of the X-ray diffractometer is 0.01-0.03°, the scanning speed is 0.5-2° / min, and the resolution of the scanning electron microscope is 1-5 nm, which can accurately detect the material properties.

[0025] For unqualified products, the reasons are analyzed based on the test results (such as inaccurate doping concentration, crystal structure defects, etc.), and the preparation process parameters are adjusted accordingly before re-preparation.

[0026] Furthermore, the entire preparation process is carried out in a dust-free, temperature-controlled (22-28℃), and humidity-controlled (30%-50%) environment to reduce the impact of external factors on material quality. In addition, the various devices are connected through an automated transmission system to reduce errors and contamination caused by manual operation.

[0027] Detailed quality records are kept for raw materials, intermediate products, and final products during the preparation process, including the source of raw materials, processing procedures, and test data, which facilitates quality traceability and process optimization.

[0028] Furthermore, in the high-temperature sintering doping process of step S5, a segmented sintering process is adopted. First, sintering is performed at 1000-1200℃ for 3-5 hours, then the temperature is raised to 1200-1400℃ for another 3-5 hours. This allows Cr to... 3 + More uniform and stable doping into the matrix lattice improves the performance consistency of fluorescent materials.

[0029] The anti-aging performance of the final prepared fluorescent material was tested by placing it in an environmental chamber simulating light and temperature and humidity changes (light intensity 1000-5000 lx, temperature 20-60℃, relative humidity 30%-90%) for 100-500 hours to detect its fluorescence performance decay rate and ensure that the material has good stability.

[0030] Furthermore, a type of Cr 3+ Application of doped fluorescent materials in plant grow lights:

[0031] The Cr 3+The doped fluorescent material is combined with a blue light chip or an ultraviolet light chip and encapsulated in a plant grow light. The mass fraction of the fluorescent material in the encapsulation material is 10-60%, and the encapsulation material is one or more of silicone resin, epoxy resin, or polyurethane resin.

[0032] The light emitted by the plant grow light can promote plant photosynthesis, increase plant growth rate, increase plant chlorophyll content, and enhance plant stress resistance. Its spectrum matches the absorption spectrum of plant photosynthesis and has a high light intensity distribution in the 600-800nm ​​red light band.

[0033] The plant grow light has a luminous efficiency of 80-150 lm / W and a color rendering index greater than 80. It can simulate the spectral characteristics of natural sunlight and provide a suitable lighting environment for plants. It is suitable for various plant cultivation scenarios such as greenhouses and indoor plant cultivation.

[0034] The heat dissipation structure of the plant grow light uses aluminum heat sink fins or heat pipe radiators to ensure that the temperature of the lamp remains stable at 40-70℃ during long-term operation, thus extending the lamp's service life. In addition, the lamp housing is made of polycarbonate or glass materials with good UV resistance and weather resistance to protect the internal components and ensure uniform light transmission.

[0035] (III) Beneficial Technical Effects

[0036] In terms of fluorescent material properties, by precisely controlling Cr 3+ By adjusting the doping concentration and optimizing the preparation process, the material can emit red light with a peak wavelength between 600-800 nm and high spectral purity under ultraviolet or blue light excitation. Its luminous efficiency is high, increasing by 30%-50% compared to some traditional fluorescent materials. This allows for more effective provision of red light for plant photosynthesis in plant supplemental lighting applications, promoting the absorption and utilization of light energy by plants.

[0037] For plant growth, applying this fluorescent material to plant grow lights can significantly improve plant growth rate. Experiments show that, within the same growth cycle, plants irradiated with grow lights containing the fluorescent material of this invention exhibit significantly improved growth indicators such as plant height, stem diameter, and leaf number compared to plants using traditional grow lights; for example, plant height can increase by 20%-30%. Simultaneously, the chlorophyll content of the plants also increases, by 15%-25%, which helps improve the efficiency of photosynthesis, enabling the plants to synthesize more organic matter and provide a more sufficient energy and material basis for their growth.

[0038] In terms of plant stress resistance, this supplemental lighting can enhance plants' ability to resist adverse environments. Under adverse conditions such as low temperature and low light, plants exposed to it can better maintain their physiological balance, reduce the incidence of pests and diseases, and lower the risk of growth inhibition or death caused by environmental stress.

[0039] From the perspective of overall performance, when combined with blue or ultraviolet light chips, plant grow lights can achieve a luminous efficiency of 80-150 lm / W and a color rendering index greater than 80. This effectively simulates the spectral characteristics of natural sunlight, providing a suitable lighting environment for plants. This is not only suitable for large-scale greenhouse cultivation, improving crop yield and quality, but also for indoor plant cultivation, making it easier for people to cultivate healthy and aesthetically pleasing ornamental plants. It has broad application prospects and significant economic and social benefits. Detailed Implementation

[0040] Example 1

[0041] Cr 3+ Preparation of doped aluminate fluorescent materials

[0042] Raw material preparation and pretreatment

[0043] Alumina (Al₂O₃) was selected as the aluminum source, lithium carbonate (Li₂CO₃) as the alkali metal source, and chromium nitrate (Cr(NO₃)₃) as the chromium source. 3+ Source. Al2O3, Li2CO3, and Cr(NO3)3 were ground separately in a mortar to control the particle size of the raw materials to 5-15 μm. Then, the ground raw materials were placed in a vacuum drying oven and dried at 50℃ and 0.05 MPa for 4 hours to remove moisture and impurities.

[0044] Initial mixing

[0045] The processed raw materials were precisely weighed according to the stoichiometric ratio of LiAl2O4 and placed in a stainless steel ball mill jar. Zirconia balls were added at a ball-to-material ratio of 6:1. A planetary ball mill was used for milling for 4 hours at a speed of 400 rpm to ensure initial homogeneity of the raw materials. The ball mill jar was cleaned with acetone and dried before use.

[0046] Pre-sintering

[0047] The ball-milled mixture was transferred to an alumina crucible and placed in a high-temperature furnace for pre-sintering at 900°C for 3 hours in an air atmosphere at a heating rate of 5°C / min. The pre-sintered material was then allowed to cool naturally to room temperature.

[0048] Secondary mixing and addition of flux

[0049] The pre-sintered material is ball-milled again for 3 hours (under the same conditions as the initial mixing). Then, ammonium fluoride is added as a flux at 5% of the total mass of the raw materials, and ball-milling is continued for 1.5 hours to ensure uniform dispersion of the flux. The flux needs to be ground to a particle size of 1-3 μm and passed through a 300-mesh sieve before being added.

[0050] High-temperature sintering doping

[0051] The material after secondary mixing is placed back into a high-temperature furnace and sintered at 1200℃ for 8 hours to achieve Cr. 3+ The dopant is incorporated into the matrix lattice, and the sintering atmosphere is nitrogen, with a heating rate of 8°C / min. The heating element of the high-temperature furnace is a silicon molybdenum rod, which allows for precise temperature control with fluctuations within ±3°C. After sintering, the material is cooled to room temperature at a rate of 5°C / min under nitrogen protection.

[0052] Post-processing

[0053] The sintered material was first coarsely crushed using a jaw crusher, and then ground to a particle size of 15-25 μm using a planetary ball mill. It was then washed four times alternately with deionized water and ethanol, followed by centrifugation at 3000 rpm for 10 minutes after each wash. Finally, it was dried in a 90℃ forced-air drying oven for 4 hours to obtain Cr. 3+ Doped aluminate fluorescent materials.

[0054] Performance testing and screening

[0055] The emission spectrum of the fluorescent material under blue light (450 nm) excitation was detected using a fluorescence spectrometer (xenon lamp as the excitation source, spectral resolution of 0.5 nm), with a peak wavelength of 680 nm. X-ray diffraction (scanning step size of 0.02°, scanning speed of 1° / min) confirmed the material's crystal structure to be cubic, with a grain size of 10-20 μm, meeting the requirements.

[0056] Application and effects of plant grow lights

[0057] The fluorescent material was combined with a blue light chip and encapsulated in a plant grow light, with the fluorescent material comprising 30% of the encapsulation material (silicone resin). The plant grow light's heat dissipation structure uses aluminum heat sinks to ensure a stable temperature of 50-60℃ during prolonged operation. The lamp housing is made of polycarbonate. When this grow light was used in greenhouse tomato cultivation, the plant height increased by 25% compared to using traditional high-pressure sodium lamps, chlorophyll content increased by 20%, and fruit yield increased by 18% during the growing season.

[0058] Example 2

[0059] Cr 3+ Preparation of doped silicate fluorescent materials

[0060] Raw material preparation and pretreatment

[0061] Using silicon dioxide (SiO2) as the silicon source, calcium carbonate (CaCO3) as the alkaline earth metal source, and chromium acetate (Cr(CH3COO)3) as the chromium source... 3+ Source. All raw materials are ground to a particle size of 8-18μm and dried at 60℃ and a vacuum of 0.03MPa for 3.5 hours.

[0062] Initial mixing

[0063] Weigh the material according to the stoichiometric ratio of CaSiO3, place it in a ceramic ball mill jar, with a ball-to-material ratio of 5:1, and mill for 5 hours at a speed of 350 rpm. The milling media are agate balls. The ball mill jar should be cleaned and dried with ethanol before use.

[0064] Pre-sintering

[0065] The mixed raw materials were pre-sintered at 950℃ for 2.5 hours (nitrogen atmosphere, heating rate 4℃ / min), and then cooled before proceeding to the next step.

[0066] Secondary mixing and addition of flux

[0067] After ball milling for another 2.5 hours, add boric acid flux (particle size 2-4μm, passing through a 250-mesh sieve) at 3% of the total mass of the raw materials, and ball mill for 1.2 hours.

[0068] High-temperature sintering doping

[0069] The sample was placed in a high-temperature furnace and sintered at 1300℃ for 7 hours (argon atmosphere, heating rate 6℃ / min). The heating element was a silicon carbide rod. During sintering, a pressure sensor monitored the pressure inside the furnace (accuracy ±0.05MPa). The sample was cooled with the furnace.

[0070] Post-processing

[0071] The particles were processed to a particle size of 12-22μm by a crusher and ball mill, ultrasonically assisted washing (ultrasonic frequency 30kHz, 15 minutes), and dried in a vacuum drying oven at 85℃ (vacuum degree 0.08MPa, 4 hours).

[0072] Performance testing and screening

[0073] The peak wavelength of the emission spectrum under ultraviolet light (365nm) excitation was 720nm, as measured by a fluorescence spectrometer (mercury lamp excitation, spectral resolution of 0.3nm). The crystal structure was determined to be orthorhombic with a grain size of 8-15μm by an X-ray diffractometer (scanning step size of 0.015°, speed of 0.8° / min), and the crystal passed the screening.

[0074] Application and effects of plant grow lights

[0075] The UV chip is packaged with fluorescent material comprising 40% by mass in epoxy resin. Heat dissipation utilizes a heat pipe radiator with a glass outer shell. When used for indoor cultivation of pothos, the number of leaves increased by 30% and stem diameter by 22% within two months compared to under ordinary fluorescent lighting; the leaves were also more vibrant green, and the plant exhibited healthier growth.

[0076] Example 3

[0077] Cr 3+ Preparation of doped phosphate fluorescent materials

[0078] Raw material preparation and pretreatment

[0079] Potassium dihydrogen phosphate (KH₂PO₄) was selected as the phosphorus source, strontium oxide (SrO) as the alkaline earth metal source, and chromium oxide (Cr₂O₃) as the chromium source. 3+ Source. The raw material is ground to 6-16μm and dried at 55℃ and 0.04MPa vacuum for 4.5 hours.

[0080] Initial mixing

[0081] Weigh the SrPO4 according to the specified ratio, place it in a stainless steel ball mill jar, with a ball-to-material ratio of 7:1, and mill for 3.5 hours at a speed of 450 rpm. Clean and dry the ball mill jar as in Example 1.

[0082] Pre-sintering

[0083] Pre-sinter at 1000℃ for 3.5 hours (air atmosphere, heating rate 6℃ / min), then proceed with operation after cooling.

[0084] Secondary mixing and addition of flux

[0085] After a second ball milling of 3.5 hours, sodium fluoride flux (particle size 1-4 μm, passed through a 200-mesh sieve) was added at a mass ratio of 4%, and the mixture was ball milled again for 1.8 hours.

[0086] High-temperature sintering doping

[0087] Sintering at 1100℃ for 9 hours (nitrogen atmosphere, heating rate 7℃ / min), heating with silicon molybdenum rod, cooling at 4℃ / min under nitrogen protection.

[0088] Post-processing

[0089] The particles were crushed and ball-milled to a particle size of 18-28 μm, then washed and centrifuged alternately (3500 rpm for 12 minutes), and dried in a 95℃ forced-air drying oven for 3.5 hours.

[0090] Performance testing and screening

[0091] Fluorescence spectroscopy (xenon lamp excitation, spectral resolution of 0.8 nm) detected an emission spectrum peak of 650 nm under blue light (460 nm) excitation. X-ray diffraction (scanning step size of 0.025°, speed of 1.5° / min) confirmed that the crystal structure is monoclinic with a grain size of 15-25 μm, which meets the requirements.

[0092] Application and effects of plant grow lights

[0093] The blue light chip is packaged with fluorescent material comprising 20% ​​by mass in polyurethane resin. It features aluminum heat sink fins for heat dissipation and a polycarbonate outer shell. Used for rose cultivation in greenhouses, it increases rose flower diameter by 15% and extends the flowering period by 10% compared to traditional supplemental lighting, resulting in more vibrant flower colors and higher overall ornamental value.

[0094] Comparative example:

[0095] Preparation and application of traditional fluorescent materials

[0096] Preparation of fluorescent materials

[0097] Using common commercial phosphors (non-Cr) 3+ (Doped), its matrix is ​​silicate, and it has not undergone special doping and optimization process treatment.

[0098] Application and effects of plant grow lights

[0099] The conventional phosphor was combined with a blue light chip and encapsulated in a plant grow light, with the phosphor comprising 30% of the encapsulation material by mass. In a greenhouse tomato cultivation experiment similar to Example 1, the tomato plant height increased by only 10%, chlorophyll content increased by 8%, and fruit yield increased by 5%, far lower than the effect of using the fluorescent material of the present invention in Example 1. In an indoor pothos cultivation experiment, the number of leaves increased by 12%, and stem diameter increased by 8%, also significantly less than the effect of Example 2. In a rose cultivation experiment, flower diameter increased by 5%, and flowering period was extended by 3%, again less than the performance of the fluorescent material of the present invention in Example 3.

[0100] Conclusion: The Cr involved in Examples 1-3 3+ The doped fluorescent materials outperform the comparative conventional fluorescent materials in many aspects. Regarding material properties, the examples exhibit clearly defined Cr... 3+ The doping source, precise emission spectrum peak wavelength under specific excitation light, well-defined and ordered crystal structure, and controllable grain size, while the comparative example has no special doping and its related properties are not optimized. In plant supplemental lighting applications, the examples significantly promoted plant growth in their respective scenarios; for example, Example 1 increased tomato plant height by 25%, chlorophyll content by 20%, and fruit yield by 18%, while the comparative example showed a smaller increase. This indicates that the Cr of the present invention...3+ Doped fluorescent materials can better meet the light requirements of plants, effectively improve the quality and yield of plant growth, and have outstanding advantages in the fields of agriculture and horticulture, providing strong support for the development of plant supplemental lighting technology.

[0101] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A type of Cr 3+ A method for preparing doped fluorescent materials, characterized in that, Includes the following steps: S1: Raw material weighing and pretreatment. Weigh the matrix raw material and Cr-containing raw material. 3+ The raw materials, including the matrix, are oxides, carbonates, nitrates, and halides of alkali metals or alkaline earth metals, containing Cr. 3+ The raw materials are chromium oxide, nitrate, and acetate. Each raw material is ground to a particle size of 5-20 μm and then dried in an oven at 50-70℃ for 3-6 hours to remove moisture and impurities. S2: Initial mixing. Place the processed raw materials in a ball mill jar made of stainless steel or ceramic. Use zirconia balls or agate balls as the milling media. The ball-to-material ratio is 4:1-8:

1. Mill the raw materials in a planetary ball mill for 3-6 hours at a speed of 300-500 rpm to ensure that the raw materials are initially mixed evenly. S3: Pre-sintering. The ball-milled mixed raw materials are transferred to an alumina crucible and placed in a high-temperature furnace for pre-sintering at 800-1000℃ for 2-5 hours. The sintering atmosphere is air or nitrogen, and the heating rate is 3-8℃ / minute. S4: Secondary mixing and addition of flux. The pre-sintered material is ball-milled again for 2-4 hours under the same conditions as the initial mixing. Then, flux, including ammonium fluoride, boric acid or sodium fluoride, is added at 2-8% of the total mass of the raw materials. Ball milling continues for 1-2 hours to ensure uniform dispersion of the flux. S5: High-temperature sintering doping. The material after secondary mixing is placed back into a high-temperature furnace and sintered at 1000-1400℃ for 6-10 hours to achieve Cr doping. 3+ Doping is incorporated into the matrix lattice, and the sintering atmosphere is nitrogen or an inert gas, including argon. The heating rate is 5-10℃ / min, and the cooling is carried out by furnace cooling or cooling at a rate of 3-8℃ / min under inert gas protection. S6: Post-processing. The sintered material is first coarsely crushed by a jaw crusher, then ground to a particle size of 10-30 μm by a planetary ball mill. It is then washed alternately with deionized water and ethanol 3-5 times, and finally dried in a forced-air drying oven at 80-100℃ for 3-5 hours to obtain Cr. 3+ Doped fluorescent materials; S7: Performance testing and screening. Fluorescence spectrometer is used to detect the emission spectrum of fluorescent materials under ultraviolet or blue light excitation to ensure that the peak wavelength is between 600-800nm. At the same time, X-ray diffraction is used to detect the crystal structure of the material and scanning electron microscopy is used to detect the grain size. Products that meet the requirements are screened out, and unqualified products are returned for reprocessing.

2. The preparation method according to claim 1, characterized in that: In step S1, the grinding equipment is a vibratory mill or an air jet mill, which can more efficiently control the particle size of the raw material within the required range, and the drying process is carried out in a vacuum environment with a vacuum degree of 0.02-0.08 MPa. In step S2, the ball mill is equipped with a cooling system consisting of a water-cooled jacket or an air-cooled device to prevent changes in the properties of the raw materials due to frictional heat during the ball milling process. The ball mill jar must be cleaned with acetone or ethanol and dried before use.

3. The preparation method according to claim 1, characterized in that: In step S3, the furnace chamber of the high-temperature furnace is made of high-purity alumina or mullite and is equipped with an automatic temperature control system to keep the temperature fluctuation within ±3℃, while monitoring the oxygen or nitrogen content of the atmosphere inside the furnace in real time. In step S4, the flux needs to be ground to a particle size of 1-5 μm and passed through a 200-400 mesh sieve before being added.

4. The preparation method according to claim 1, characterized in that: In step S5, the heating element of the high-temperature furnace is a silicon carbide rod or a silicon molybdenum rod, which heats up rapidly and has a uniform temperature distribution. During the sintering process, the pressure inside the furnace can be monitored by a pressure sensor, and the sintering process parameters can be adjusted according to the pressure changes. In step S6, key components of the crusher and ball mill, including the crushing tooth plate and the inner wall of the ball mill jar, are made of wear-resistant materials, including hard alloy or ceramic coatings, to extend the service life of the equipment. During the washing process, ultrasonic-assisted washing is carried out for 10-20 minutes at an ultrasonic frequency of 20-40kHz.

5. The preparation method according to claim 1, characterized in that: In step S7, the excitation source of the fluorescence spectrometer is a xenon lamp or a mercury lamp with a spectral resolution of 0.1-1 nm; the scanning step size of the X-ray diffractometer is 0.01-0.03°; the scanning speed is 0.5-2° / min; and the resolution of the scanning electron microscope is 1-5 nm. For substandard products, the reasons are analyzed based on the test results, and the preparation process parameters are adjusted accordingly before re-preparation.

6. The preparation method according to claim 1, characterized in that: The entire preparation process is carried out in a dust-free, temperature-controlled room of 22-28℃ and humidity of 30%-50%, which reduces the impact of external factors on material quality, and the various devices are connected by an automated transmission system. Detailed quality records are kept for raw materials, intermediate products, and final products during the preparation process, including the source of raw materials, processing procedures, and test data, which facilitates quality traceability and process optimization.

7. The preparation method according to claim 1, characterized in that: In the high-temperature sintering doping process of step S5, a segmented sintering process is adopted. First, sintering is carried out at 1000-1200℃ for 3-5 hours, and then the temperature is raised to 1200-1400℃ for 3-5 hours. The anti-aging performance of the finally prepared fluorescent material was tested. The material was placed in an environmental chamber simulating light and temperature and humidity changes, with light intensity of 1000-5000 lx, temperature of 20-60℃, and relative humidity of 30%-90%, and tested continuously for 100-500 hours to detect its fluorescence performance decay rate.

8. A Cr prepared according to any one of claims 1-7 3+ The application of doped fluorescent materials in plant grow lights is characterized by: The Cr 3+ The doped fluorescent material is combined with a blue light chip or an ultraviolet light chip and encapsulated in a plant grow light. The mass fraction of the fluorescent material in the encapsulation material is 10-60%. The encapsulation material is one or more of silicone resin, epoxy resin or polyurethane resin. The light emitted by the plant grow light can promote photosynthesis in plants, increase plant growth rate, increase chlorophyll content and enhance plant stress resistance. Its spectrum matches the absorption spectrum of plant photosynthesis and has a high light intensity distribution in the 600-800nm ​​red light band. The luminous efficiency of the plant grow light reaches 80-150 lm / W, and the color rendering index is greater than 80. The heat dissipation structure of the plant grow light uses aluminum heat sink fins or heat pipe radiators, and the lamp housing is made of polycarbonate or glass material with good UV resistance and weather resistance to protect the internal components and ensure uniform light transmission.

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