Preparation of Cr < 3 + >-doped fluorescent material and application of Cr < 3 + >-doped fluorescent material in plant light supplement lamp

Abstract

The invention discloses preparation of a Cr < 3 + >-doped fluorescent material and application of the Cr < 3 + >-doped fluorescent material in a plant light supplement lamp, and relates to the technical field of preparation of Cr < 3 + >-doped fluorescent materials.The preparation method comprises the following steps that a matrix raw material and a Cr < 3 + >-containing raw material are weighed according to the stoichiometric ratio, and the matrix raw material and the Cr < 3 + >-containing raw material are ground and stored in a dryer; putting the raw materials into a ball milling tank, and carrying out planetary ball milling for 3-6 hours; transferring to an alumina crucible, and pre-sintering for 2-5 hours; after secondary ball milling, adding a fluxing agent; sintering in a high-temperature furnace for 6-10 hours, and cooling along with the furnace or under the protection of inert gas; the preparation method comprises the following steps: coarsely crushing, grinding to 10-30 microns, alternately cleaning with deionized water and ethanol, drying in an air dry oven, detecting and screening 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 light-emitting efficiency is high, the spectrum adapts to plant photosynthetic absorption, the plant growth can be promoted when the light-supplementing lamp is applied, the plant height and the chlorophyll content are obviously increased, the natural spectrum is simulated, and the light-supplementing lamp is suitable for multiple cultivation scenes.

Description

Technical Field

[0001] The present invention relates to Cr 3+ The technical field of preparation of doped fluorescent materials, specifically Cr 3+ Preparation of doped fluorescent materials and their application in plant supplementary lighting. Background Art

[0002] With the continuous development of modern agricultural technology, plant lighting technology plays an increasingly important role in the fields of facility agriculture, plant factories and indoor gardening. Plant growth is inseparable from light, and different wavelengths of light have different effects on plant photosynthesis, morphological construction, physiological metabolism, etc.

[0003] In the natural environment, sunlight is the main light source for plant growth, and its spectrum covers a wide range from ultraviolet to infrared. However, in some specific planting environments, such as greenhouses in winter or rainy days, natural light is insufficient; plant factories rely entirely on artificial light sources due to the lack of natural lighting; when ornamental plants are cultivated indoors, the indoor light intensity and spectrum often cannot meet the needs of plants. Therefore, artificial plant supplementary lights came into being.

[0004] Traditional plant lighting mainly includes incandescent lamps, fluorescent lamps, high-pressure sodium lamps, etc. Incandescent lamps have low luminous efficiency, and most of the electrical energy is converted into heat energy rather than light energy. In addition, there are more infrared components in their spectrum and relatively less visible light. When used for plant lighting, it not only wastes energy, but also has limited effect on promoting plant growth. Although fluorescent lamps have improved the luminous efficiency to a certain extent, the light conversion efficiency of phosphors still needs to be improved, and the matching degree of their spectral distribution with the absorption spectrum of plant photosynthesis is not ideal, and cannot fully meet the needs of plants for specific wavelengths of light. High-pressure sodium lamps mainly emit orange-yellow light, with more red light components, but other light components that are beneficial to plant growth, such as blue light, are relatively lacking. Long-term use will lead to problems such as leggy plants and thin stems.

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

[0006] Cr 3+ The doped fluorescent material has unique optical properties. When excited by light of a specific wavelength, it can emit red light that matches the absorption spectrum of plant photosynthesis. 3+Doped fluorescent materials and their applications in plant lighting are expected to overcome the shortcomings of traditional plant lighting and existing fluorescent materials. Through reasonable design and preparation process optimization, efficient and precise plant lighting can be achieved, the growth quality and yield of plants can be improved, and the growing demand for plant lighting technology in modern agriculture can be met, which will promote the further development of fields such as facility agriculture and plant factories. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] In view of the deficiencies in the prior art, the present invention provides a preparation method of a Cr3+-doped fluorescent material and its application in a plant supplementary light.

[0009] (II) Technical solution

[0010] A Cr 3+ The method for preparing the doped fluorescent material comprises the following steps:

[0011] S1: Raw material weighing and pretreatment, weighing matrix raw materials and Cr-containing 3+ Raw materials, matrix raw materials are oxides, carbonates, nitrates, 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° C. for 3-6 hours to remove moisture and impurities, and each raw material is stored in a dryer to prevent deliquescence.

[0012] S2: Initial mixing: Place the processed raw materials in a ball mill (made of stainless steel or ceramic, with zirconia balls or agate balls as the milling medium, 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 make the raw materials preliminarily mixed and uniform.

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

[0014] S4: Secondary mixing and adding flux: the pre-sintered material is ball-milled again for 2-4 hours (same conditions as the initial mixing), and then a flux (such as ammonium fluoride, boric acid or sodium fluoride) is added according to 2-8% of the total mass of the raw materials, and the ball milling is continued for 1-2 hours to ensure that the flux is evenly dispersed.

[0015] S5: high temperature sintering and doping, the secondary mixed materials are put into the high temperature furnace again, and sintered at 1000-1400℃ for 6-10 hours to achieve Cr 3+Doping is performed into the matrix lattice, the sintering atmosphere is nitrogen or inert gas (such as argon), the heating rate is 5-10°C / min, and the cooling is performed by furnace cooling or cooling at a rate of 3-8°C / min under the protection of inert gas.

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

[0017] S7: Performance testing and screening. Use a fluorescence spectrometer 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, detect the crystal structure (through X-ray diffractometer) and grain size (through scanning electron microscope) of the material to screen out products that meet the requirements, and return unqualified products for reprocessing.

[0018] Furthermore, in step S1, the grinding equipment is a vibration mill or a 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 0.02-0.08MPa, which can further reduce residual impurities.

[0019] In step S2, the ball mill is equipped with a cooling system (such as a water-cooling jacket or an air-cooling device) to prevent the properties of the raw materials from changing due to frictional heat during the ball milling process. The ball mill jar needs to be cleaned and dried with acetone or ethanol 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 properties, and is equipped with an automatic temperature control system, which can control temperature fluctuations within ±3°C, and can monitor the oxygen content or nitrogen content of the furnace atmosphere in real time (with an accuracy of ±0.1%).

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

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

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

[0024] Furthermore, in step S7, the excitation light source of the fluorescence spectrometer is a xenon lamp or a mercury lamp, the spectral resolution is 0.1-1nm, the scanning step of the X-ray diffractometer is 0.01-0.03°, the scanning speed is 0.5-2° / minute, and the resolution of the scanning electron microscope is 1-5nm, which can accurately detect 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, constant temperature (22-28°C), and constant humidity (30%-50%) environmentally controlled room to reduce the impact of external factors on material quality, and each device is connected by an automated transmission system to reduce errors and pollution caused by manual operation.

[0027] The raw materials, intermediates and final products in the preparation process have detailed quality record files, including the source of raw materials, processing procedures, test data, etc., to facilitate quality traceability and process optimization.

[0028] Furthermore, in the high temperature sintering doping process of step S5, a staged sintering process is adopted, first sintering at 1000-1200°C for 3-5 hours, and then heating to 1200-1400°C for 3-5 hours, so that Cr 3+ More uniform and stable doping into the matrix lattice improves the performance consistency of the fluorescent material.

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

[0030] Furthermore, a Cr 3+ Application of doped fluorescent materials in plant supplementary lighting:

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

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

[0033] The luminous efficiency of the plant fill light reaches 80-150lm / W, and the color rendering index is 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 fill light adopts aluminum heat sink fins or heat pipe radiator to ensure that the temperature of the lamp is stable at 40-70℃ when working for a long time, extending the service life of the lamp. The lamp shell is made of polycarbonate or glass material 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 performance, by precisely controlling Cr 3+ By optimizing the doping concentration and the preparation process, the material can emit red light with a peak wavelength between 600-800nm ​​and high spectral purity under ultraviolet or blue light excitation. Its luminous efficiency is high, which can be increased by 30%-50% compared with some traditional fluorescent materials. This makes it possible to more effectively provide plants with the red light required for photosynthesis in the application of plant supplementary lighting, and promote the absorption and utilization of light energy by plants.

[0037] As for plant growth, the application of the fluorescent material in plant fill-in lights can significantly increase the growth rate of plants. Experiments show that in the same growth cycle, the growth indicators such as plant height, stem thickness, and number of leaves of plants illuminated by fill-in lights containing the fluorescent material of the present invention are significantly improved compared with those of plants using traditional fill-in lights. For example, plant height can be increased by 20%-30%. At the same time, the chlorophyll content of plants is also increased, which can be enhanced by 15%-25%, which helps to improve the photosynthesis efficiency of plants, allowing plants to synthesize more organic matter and provide more sufficient energy and material basis for their own growth.

[0038] In terms of plant stress resistance, the supplementary light can enhance the resistance of plants to adverse environments. Under adverse conditions such as low temperature and weak light, the plants irradiated by it can better maintain their own physiological balance, reduce the incidence of diseases and pests, and reduce the risk of growth inhibition or death caused by environmental stress.

[0039] From the overall performance of the plant fill light, after being packaged with a blue light chip or a UV light chip, the luminous efficiency can reach 80-150lm / W, and the color rendering index is greater than 80, which can better simulate the spectral characteristics of natural sunlight and provide a suitable lighting environment for plants. This is not only suitable for large-scale greenhouse cultivation, improving the yield and quality of crops, but also suitable for indoor plant cultivation and other scenarios, allowing people to more conveniently cultivate healthy and beautiful ornamental plants, with broad application prospects and good economic and social benefits. DETAILED DESCRIPTION

[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 Cr 3+ Source. Al2O3, Li2CO3 and Cr(NO3)3 were ground in a mortar to control the particle size of the raw materials to 5-15μm. The ground raw materials were then placed in a vacuum drying oven and dried for 4 hours at 50℃ and a vacuum degree of 0.05MPa to remove moisture and impurities.

[0044] Initial Mixing

[0045] The treated raw materials were accurately weighed according to the stoichiometric ratio of LiAl2O4, placed in a stainless steel ball mill, and zirconium oxide balls were added, with a ball-to-material ratio of 6:1. The ball mill was milled in a planetary ball mill for 4 hours at a speed of 400 rpm to make the raw materials preliminarily mixed. The ball mill was cleaned with acetone and dried before use.

[0046] Pre-sintering

[0047] The ball-milled mixed raw material 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 naturally cooled to room temperature.

[0048] Secondary mixing and addition of flux

[0049] The pre-sintered material was ball-milled again for 3 hours (same conditions as the initial mixing), and then ammonium fluoride was added as a flux at 5% of the total weight of the raw materials, and the ball milling was continued for 1.5 hours to ensure that the flux was evenly dispersed. The flux should be ground to a particle size of 1-3 μm before addition and passed through a 300 mesh sieve.

[0050] High temperature sintering doping

[0051] The secondary mixed materials are put into the high temperature furnace again and sintered at 1200℃ for 8 hours to achieve Cr 3+ Doping into the matrix lattice, sintering atmosphere is nitrogen, heating rate is 8℃ / min. The heating element of the high temperature furnace is silicon molybdenum rod, which can accurately control the temperature, and the temperature fluctuation range is within ±3℃. After sintering, it is cooled to room temperature at a rate of 5℃ / min under nitrogen protection.

[0052] Post-processing

[0053] The sintered material was first crushed by a jaw crusher and then ground by a planetary ball mill to a particle size of 15-25 μm. It was then washed alternately with deionized water and ethanol for 4 times. After each washing, it was centrifuged at a speed of 3000 rpm for 10 minutes. Finally, it was dried in a 90°C 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 the excitation of blue light (450nm) was detected by a fluorescence spectrometer (the excitation light source was a xenon lamp, and the spectral resolution was 0.5nm), and its peak wavelength was 680nm. The crystal structure of the material was detected by an X-ray diffractometer (the scanning step was 0.02° and the scanning speed was 1° / min), and it was found to be a cubic crystal system with a grain size of 10-20μm, which met the requirements.

[0056] Application and effect of plant supplementary lighting

[0057] The fluorescent material is combined with a blue light chip and packaged in a plant fill light. The mass fraction of the fluorescent material in the packaging material (silicone resin) is 30%. The heat dissipation structure of the plant fill light adopts aluminum heat dissipation fins to ensure that the temperature of the lamp is stable at 50-60°C when working for a long time. The lamp shell is made of polycarbonate material. The fill light is used to grow tomatoes in greenhouses. During the growth cycle, the height of the tomato plants increased by 25% compared with the use of traditional high-pressure sodium fill lights, the chlorophyll content increased by 20%, and the fruit yield increased by 18%.

[0058] Example 2

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

[0060] Raw material preparation and pretreatment

[0061] Silicon dioxide (SiO2) is used as silicon source, calcium carbonate (CaCO3) is used as alkaline earth metal source, and chromium acetate (Cr(CH3COO)3) is used as Cr 3+ Each raw material was ground to a particle size of 8-18 μm and dried at 60°C and a vacuum degree of 0.03 MPa for 3.5 hours.

[0062] Initial Mixing

[0063] The material was weighed according to the stoichiometric ratio of CaSiO3 and placed in a ceramic ball mill with a ball-to-material ratio of 5:1. The ball mill was milled for 5 hours at a speed of 350 rpm. The ball mill medium was agate balls. The ball mill was cleaned and dried with ethanol before use.

[0064] Pre-sintering

[0065] The mixed raw materials were pre-sintered at 950° C. for 2.5 hours (nitrogen atmosphere, heating rate 4° C. / 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, boric acid flux (particle size 2-4 μm, passed through a 250 mesh sieve) was added at 3% of the total mass of the raw materials, and ball milling was continued for 1.2 hours.

[0068] High temperature sintering doping

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

[0070] Post-processing

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

[0072] Performance testing and screening

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

[0074] Application and effect of plant supplementary lighting

[0075] Packaged with UV chip, the fluorescent material is 40% by mass in epoxy resin. Heat dissipation uses heat pipe radiator, and the shell is glass. Used for indoor cultivation of green radish, the number of green radish leaves increased by 30% in two months compared with ordinary fluorescent lamps, the stem thickness increased by 22%, and the leaves were greener and the growth state was healthier.

[0076] Example 3

[0077] Cr 3+ Preparation of Phosphate-doped 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 Cr 3 + The raw materials were ground to 6-16 μm and dried at 55 °C and vacuum degree 0.04 MPa for 4.5 hours.

[0080] Initial Mixing

[0081] Weigh according to the SrPO4 metering ratio, place in a stainless steel ball mill, with a ball-to-material ratio of 7:1, and ball mill for 3.5 hours at a speed of 450 rpm. The ball mill is cleaned and dried in the same way as in Example 1.

[0082] Pre-sintering

[0083] Pre-sintering was performed at 1000°C for 3.5 hours (air atmosphere, heating rate 6°C / min), and then the product was operated after cooling.

[0084] Secondary mixing and addition of flux

[0085] After the second ball milling for 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 ball milling was continued for another 1.8 hours.

[0086] High temperature sintering doping

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

[0088] Post-processing

[0089] The product was crushed and ball-milled to a particle size of 18-28 μm, washed and centrifuged alternately (speed 3500 rpm, time 12 minutes), and dried in a 95°C forced air drying oven for 3.5 hours.

[0090] Performance testing and screening

[0091] Fluorescence spectrometer (xenon lamp excitation, spectral resolution of 0.8nm) detected the emission spectrum peak at 650nm under blue light (460nm) excitation, and X-ray diffractometer (scanning step 0.025°, speed 1.5° / min) detected the crystal structure to be monoclinic, with a grain size of 15-25μm, which met the requirements.

[0092] Application and effect of plant supplementary lighting

[0093] Packaged with blue light chip, the fluorescent material is 20% by mass in polyurethane resin. Aluminum heat sink fins are used for heat dissipation, and the shell is polycarbonate. It is used for rose cultivation in flower planting greenhouses. The diameter of rose flowers increases by 15% compared with traditional fill light, the flowering period is extended by 10%, the flower color is brighter, and the overall ornamental value is higher.

[0094] Comparative Example:

[0095] Preparation and application of traditional fluorescent materials

[0096] Fluorescent material preparation

[0097] Using ordinary commercial phosphor (non-Cr 3+ doping), the matrix is ​​silicate, and no special doping and optimization process treatment is performed.

[0098] Application and effect of plant supplementary lighting

[0099] The traditional phosphor and the blue light chip were packaged in a plant fill light, and the mass fraction of the phosphor in the packaging material was 30%. In the same greenhouse tomato planting experiment as in Example 1, the height of the tomato plants increased by only 10%, the chlorophyll content increased by 8%, and the fruit yield increased by 5%, which was far lower than the effect of using the fluorescent material of the present invention in Example 1. In the indoor green radish cultivation experiment, the number of leaves increased by 12% and the stem thickness increased by 8%, which was also significantly inferior to the effect of Example 2. In the rose planting experiment, the flower diameter increased by 5% and the flowering period was extended by 3%, which was also inferior to the performance of the fluorescent material of the present invention in Example 3.

[0100]

[0101]

[0102] Conclusion: The Cr involved in Examples 1-3 3+ The doped fluorescent material is superior to the conventional fluorescent material in many aspects. 3+The doping source, the precise emission spectrum peak wavelength under specific excitation light, the clear and ordered crystal structure and the controllable grain size, while the comparative example has no special doping and the relevant characteristics are not optimized. In the application of plant supplementary lighting, the embodiments significantly promote plant growth in their respective scenarios. For example, Example 1 increases tomato plant height by 25%, chlorophyll by 20%, and fruit yield by 18%, while the comparative example has a small improvement. This shows that the Cr 3+ Doped fluorescent materials can better meet the needs of plant lighting supplementation, effectively improve plant growth quality and yield, have outstanding application advantages in agriculture and horticulture, and provide strong support for the development of plant lighting supplementation technology.

[0103] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A Cr 3 + The preparation method of the doped fluorescent material is characterized in that, The following steps are involved: S1: Raw material weighing and pretreatment, weighing matrix raw materials and Cr-containing 3 + Raw materials, the matrix raw materials are oxides, carbonates, nitrates, 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°C for 3-6 hours to remove moisture and impurities; S2: Initial mixing: the treated raw materials are placed in a ball milling jar made of stainless steel or ceramic, the ball milling medium is zirconia balls or agate balls, the ball-to-material ratio is 4:1-8:1, and the raw materials are ball milled in a planetary ball mill for 3-6 hours at a ball milling speed of 300-500 rpm to make the raw materials preliminarily mixed; S3: Pre-sintering: the ball-milled mixed raw material is transferred to an alumina crucible, and placed in a high-temperature furnace for pre-sintering at 800-1000°C for 2-5 hours. The sintering atmosphere is air or nitrogen, and the heating rate is 3-8°C / min. S4: Secondary mixing and adding flux, the pre-sintered material is ball-milled again for 2-4 hours under the same conditions as the initial mixing, and then a flux including ammonium fluoride, boric acid or sodium fluoride is added at 2-8% of the total weight of the raw materials, and the ball milling is continued for 1-2 hours to ensure that the flux is evenly dispersed; S5: high temperature sintering and doping, the secondary mixed materials are put into the high temperature furnace again, and sintered at 1000-1400℃ for 6-10 hours to achieve Cr 3 + doping into the matrix lattice, the sintering atmosphere is nitrogen or inert gas, including argon, the heating rate is 5-10℃ / min, and the temperature is cooled by furnace cooling or cooling at a rate of 3-8℃ / min under the protection of inert gas; S6: Post-treatment: the sintered material is first crushed by a jaw crusher, then ground by a planetary ball mill to a particle size of 10-30 μm, then washed alternately with deionized water and ethanol for 3-5 times, and finally dried in a blast drying oven at 80-100 ° C for 3-5 hours to obtain Cr 3 +Doped fluorescent materials; S7: Performance testing and screening. Use a fluorescence spectrometer 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, use an X-ray diffractometer to detect the crystal structure of the material and a scanning electron microscope 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 vibration mill or a 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 0.02-0.08MPa; In step S2, the ball mill is equipped with a cooling system of a water-cooled jacket or an air-cooled device to prevent the properties of the raw materials from changing due to frictional heat during the ball milling process. The ball mill jar needs to be cleaned and dried with acetone or ethanol before use.

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

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 carbon rod or a silicon molybdenum rod, which heats up quickly and has a uniform temperature distribution. During the sintering process, the pressure in the furnace can be monitored by a pressure sensor, and the sintering process parameters can be adjusted according to the pressure change; In step S6, key components of the crusher and ball mill, including the crushing tooth plate and the inner wall of the ball mill, are made of wear-resistant materials, including cemented carbide or ceramic coating, to extend the service life of the equipment. Ultrasonic assisted washing is used during the washing process for 10-20 minutes with an ultrasonic frequency of 20-40kHz.

5. The preparation method according to claim 1, characterized in that: In step S7, the excitation light source of the fluorescence spectrometer is a xenon lamp or a mercury lamp, the spectral resolution is 0.1-1 nm, the scanning step length 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 unqualified products, the reasons are analyzed according to 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, constant temperature 22-28°C, and constant humidity 30%-50% environment-controlled room to reduce the impact of external factors on material quality, and each device is connected by an automated transmission system; The raw materials, intermediates and final products in the preparation process have detailed quality record files, 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 and doping process of step S5, a staged sintering process is adopted, first sintering at 1000-1200°C for 3-5 hours, and then heating to 1200-1400°C for 3-5 hours; The final fluorescent material was tested for its anti-aging performance. The material was placed in an environmental chamber simulating changes in light, temperature and humidity, with a light intensity of 1000-5000lx, a temperature of 20-60°C, and a relative humidity of 30%-90%. The test was continued for 100-500 hours to detect the fluorescence performance decay rate.

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

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