Method for preparing super-long phosphorescent monodisperse SiO2 particles on large scale
Through the improved sol-gel method and high-temperature calcination technology, ultra-long phosphorescence monodispersed SiO2 particles were prepared, which solved the problems of irregular material morphology and expensive raw materials in the prior art, achieved large-scale preparation and good optical stability, and had wide application prospects.
Patent Information
- Application Number
- CN202411738054.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-03-04
AI Technical Summary
It is difficult to prepare ultra-long phosphorescence monodispersed SiO2 particles on a large scale, and in traditional methods, the material morphology is irregular, the optical behavior is static, the raw materials are expensive and have high toxicity.
The modified sol-gel method was used to add organic small molecules as dopants to the reaction precursor prepared by SiO2 to prepare SiO2 particles with oxygen or nitrogen chemical defects, and the fluorescence defect center and stable excitation triplet state were formed by high-temperature calcination to achieve the preparation of phosphorescent monodispersed SiO2 particles with long-lived life.
It has achieved large-scale preparation of ultra-long phosphorescence monodispersed SiO2 particles, the material has good optical stability, the raw materials are cheap, suitable for industrial production, and has wide application prospects in fields such as multi-mode information encryption and multi-optical response smart windows.
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Figure CN119551680A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of preparation of phosphorescent materials with regular morphology, and in particular relates to a method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence. Background Art
[0002] In nature, silicon is an extremely common element, mainly existing in the form of oxides and silicates. The simplest of these is silicon dioxide (SiO2), a compound of silicon and oxygen. SiO2 material is not only non-toxic, odorless, and environmentally friendly, but also has strong physical rigidity, low refractive index, small thermal expansion coefficient, and high insulation. Therefore, it has been widely used in solar cells, integrated circuits, optical lenses, and biomedicine. Among them, monodisperse SiO2 nanoparticles have important application value in the field of optics, especially in photonic crystal materials, due to their regular spherical morphology and good dispersibility. Traditional monodisperse SiO2 nanoparticles are prepared by sol-gel polymerization. It is synthesized by hydrolyzing an organic silicon source in an alkaline environment and then polymerizing it. However, with the rapid development of optical functional materials, the optical materials and devices formed by monodisperse SiO2 nanoparticles with a single characteristic have relatively simple performances, including optical behavior mainly relying on physical structural color, single optical morphology, and can only work under white light / natural light, which greatly limits their practical applications. Therefore, it is urgent to develop a monodisperse SiO2 nanoparticle that integrates multiple optical signals. Nowadays, some researchers have prepared fluorescent functionalized SiO2 particles by combining fluorescent materials with SiO2 particles. The photonic crystal materials prepared by this material can cleverly combine physical structural color and chemical fluorescent color, and have also made many major breakthroughs in the fields of sensing and anti-counterfeiting. However, the preparation process of fluorescent functionalized SiO2 particles is relatively complicated, and the decay lifetime of excitons in fluorescence is short (ns), resulting in the optical behavior of the prepared optical devices being still static. Recently, some researchers have combined long-life luminescent phosphorescent materials with monodisperse SiO2 nanoparticles to prepare optical devices with multiple optical morphologies. However, these current methods usually rely on simple physical mixing of commercial phosphors and SiO2 nanoparticles. The optical stability of the prepared phosphorescent monodisperse SiO2 particles is poor, and the raw materials are expensive and highly toxic. Therefore, it is urgent to develop a simple method for large-scale preparation of phosphorescent monodisperse SiO2 particles.
[0003] However, it is extremely difficult to achieve phosphorescent monodisperse colloidal particles. First, the preparation methods of traditional phosphorescent materials include molecular crystallization, polymer encapsulation and hydrothermal method. However, these methods are uncontrollable during the material growth and molding process, and the morphology of the produced materials is random and irregular. On the contrary, the current preparation method of monodisperse particles relies on the sol-gel method, which has significant differences in preparation methods. In addition, the generation of phosphorescence requires two necessary conditions, one is the presence of chemiluminescent defect centers, and the other is to stabilize these luminescent centers in a specific way, inhibit non-radiative transitions and stabilize triplet excitons. Therefore, it is very difficult to prepare this type of SiO2 phosphorescent material with a regular spherical shape, and it is necessary to find a new preparation method that can not only achieve monodisperse SiO2 particles with chemical defect centers, but also stabilize triplet excitons to achieve phosphorescent emission while ensuring morphological stability. Summary of the invention
[0004] In order to achieve the above design goals, the present invention provides a method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence. First, a modified sol-gel method is used to synthesize monodisperse SiO2 particles doped with organic small molecules, by uniformly dispersing the reaction solvent (ethanol, tetraethyl orthosilicate, organic molecule solution and ammonia water), generating active monomers through hydrolysis reaction, and then these monomers gradually polymerize to form spherical colloidal particles encapsulating organic small molecules. After complete hydrolysis and separation, organic small molecule doped monodisperse SiO2 particles are obtained, which contain other chemical defect groups other than silicon oxygen chain groups, such as oxygen and nitrogen related defect states. Subsequently, the obtained organic small molecule doped monodisperse SiO2 particles are placed in a crucible and calcined at high temperature for several hours. During the calcination process, oxygen and nitrogen related defect states gradually form luminescent centers, and the SiO2 particles are more compact in structure and form additional covalent bond networks after calcination, so that the luminescent center is supported by a more stable environment, thereby reducing the non-radiative attenuation of electrons, thereby producing long-life phosphorescence. This method has the advantages of simple preparation, cheap raw materials and large-scale production. At the same time, the prepared materials have broad application prospects in the fields of multi-mode information encryption, multi-optical responsive smart windows, photonic materials and photonic coatings.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] A method for large-scale preparation of monodisperse SiO2 particles with ultralong phosphorescence using a modified sol-gel method Organic small molecules are added as dopants to the reaction precursor solution for preparing SiO2 to prepare SiO2 particles with oxygen or nitrogen chemical defects. Then, through high-temperature calcination, fluorescent defect centers and stable excited triplet states are achieved, thereby obtaining long-life phosphorescent monodisperse SiO2 particles. The specific steps are as follows:
[0007] The first step is to prepare the organic small molecule solution:
[0008] A certain concentration of citric acid aqueous solution is prepared. The concentration of the citric acid aqueous solution is 0.075-0.15 mmol / mL. In addition to citric acid, the solute of the organic small molecule solution can also be replaced by glucose, melamine, urea, tartaric acid, terephthalic acid, ascorbic acid or coumarin; in addition, the solute can also be replaced by fluorescent dyes such as rhodamine B, rhodamine 6G, quinine sulfate and sulforhodamine B. The concentration of the dye molecule aqueous solution is 0.1-1 mmol / L. Ensure that the solute in the organic molecule aqueous solution is completely dissolved before the reaction.
[0009] The second step is to synthesize monodisperse SiO2 nanoparticles doped with organic small molecules:
[0010] The preparation method of monodisperse SiO2 nanoparticles is based on the modified Method, the citric acid aqueous solution prepared in the first step replaces the traditional Deionized water in the method. Specifically, 5-6 mL of citric acid aqueous solution, 150-230 mL of anhydrous ethanol and 15-18 mL of ammonia water are mixed in a 500 mL beaker (the capacity of the beaker can be selected according to the actual volume of the reaction liquid), the beaker is placed in a collector magnetic stirrer and stirred for 20-40 minutes, and the temperature of the mixed solution is raised to 60-65°C, then 11-12 mL of ethyl orthosilicate and 10-15 mL of anhydrous ethanol mixed solution are added, stirring is continued for 80-130 minutes and the temperature is maintained at 60-65°C, and finally a monodisperse SiO2 nanoparticle suspension doped with organic small molecules is obtained.
[0011] The ammonia solution is of analytical grade, with an ammonia content of 25%; the tetraethyl orthosilicate is of analytical grade, with a purity of 98%. During the preparation process, the beaker mouth is sealed with a sealing film to prevent the solution from volatilizing during the reaction. The liquid level of water in the collector magnetic stirrer should be higher than the liquid level of the precursor liquid in the beaker to ensure that the precursor liquid is heated evenly during the reaction. In industrial production, the proportion of the reaction solution can be enlarged in proportion, but the reaction temperature and reaction time remain fixed.
[0012] The third step is to purify SiO2 particles:
[0013] The monodisperse SiO2 nanoparticle suspension obtained in the second step is subjected to multiple centrifugal purification. The suspension is placed in a 50mL centrifuge tube and centrifuged at 6000-7000 rpm for 10-15min. The supernatant after centrifugation is discarded and the white SiO2 precipitate at the bottom is collected. The solid is then redispersed in 100-200mL ethanol and centrifuged again at 6000-7000 rpm for 10-15min. The centrifuged product is then dispersed in ultrapure water and the centrifugation process is repeated. Finally, the obtained white SiO2 precipitate is dried in a 40-60°C air drying oven to obtain a white SiO2 solid.
[0014] The fourth step is to prepare phosphorescent SiO2 nanoparticles by high temperature calcination:
[0015] The SiO2 solid obtained in the third step is ground into powder by an agate mortar and spread in an alumina crucible. The crucible is placed in a muffle furnace for calcination, with an initial temperature of 20-30°C (room temperature) and a heating rate of 170-272°C / h. After about 2-3h, the temperature is raised to 530-575°C, and the temperature is kept at 530-575°C for 2-3h, and finally cooled naturally to room temperature to obtain phosphorescent SiO2 powder.
[0016] The specification of the alumina crucible is 50mm×25mm (no strict specification, the appropriate specification can be selected according to the amount of reaction), SiO2 powder is placed in the alumina crucible and covered with a crucible of the same specification to prevent the sample from being contaminated. In addition to the alumina crucible, a quartz crucible can also be used instead. In industrial production, the size of the alumina crucible can be selected according to the output of SiO2 solid in the third step.
[0017] The beneficial effects of the present invention are as follows:
[0018] (1) The method is simple and easy to implement, and suitable for mass production: The present invention uses cheap organic small molecules to be doped into monodisperse SiO2 nano-microspheres, and directly performs high-temperature calcination in a muffle furnace to prepare persistent phosphorescent monodisperse SiO2 nano-microspheres. The raw materials are cheap, the experimental repeatability is high, and low-cost large-scale preparation is possible. The nano-microsphere particle size adjustment method is simple during the preparation process, and it is easy to prepare phosphorescent monodisperse SiO2 nano-microspheres of different particle sizes.
[0019] (2) The prepared phosphorescent monodisperse SiO2 nanospheres have good optical stability. Thanks to the rigid structure of SiO2, the luminescent groups generated inside the microspheres after calcination have good protection and confinement. After being stored in air for six months, the fluorescence intensity, phosphorescence intensity and phosphorescence lifetime of the phosphorescent SiO2 remain almost unchanged. At the same time, the invented phosphorescent monodisperse SiO2 continues to maintain its original optical properties in various organic solvents and can be recovered from organic solvents.
[0020] (3) The prepared phosphorescent monodisperse SiO2 nanospheres have low biological toxicity, which greatly reduces the cost of industrial production and transportation of the product. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the preparation process of phosphorescent SiO2 nanoparticles of the present invention.
[0022] Figure 2 The transmission electron microscope (TEM) and scanning electron microscope (SEM) images of the phosphorescent SiO2 nanoparticles of the present invention are shown in FIG.
[0023] Figure 3 It is the steady-state fluorescence spectrum, phosphorescence spectrum and lifetime spectrum of the phosphorescent SiO2 nanoparticles of the present invention.
[0024] Figure 4 These are photos of the phosphorescent SiO2 nanoparticles of the present invention under natural light, ultraviolet light, and after being turned off. DETAILED DESCRIPTION
[0025] The present invention is further described below in conjunction with specific examples, but the protection scope of the present invention is not limited thereto. Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.
[0026] Referring to the attached drawings, the meanings of the Roman numerals in the drawings are as follows: Ⅰ. Fix the reaction precursor solution (ammonia water, anhydrous ethanol, tetraethyl orthosilicate, organic molecule aqueous solution) in a heat collecting stirrer, and the water level in the heat collecting stirrer should be higher than the reaction precursor solution. Then raise the temperature of the mixed solution to 62°C and stir for 100 minutes. Ⅱ. Centrifuge the suspension of organic molecule-doped SiO2 particles after the reaction to obtain organic molecule-doped SiO2 particles. Ⅲ. Dry the obtained organic molecule-doped SiO2 particles to obtain organic molecule-doped SiO2 particle powder. Ⅳ. Place the organic molecule-doped SiO2 particle powder in an alumina (or quartz) crucible and calcine it in a muffle furnace. The initial temperature is 30°C, the heating rate is 250°C / h, and the temperature is raised to 530°C after about 2 hours, and kept at 530°C for 3 hours. Ⅴ. After the calcination is completed, the muffle furnace is cooled to room temperature, and the reacted solid powder is taken out, which is the phosphorescent SiO2 nanoparticles.
[0027] The Arabic numerals in the figure represent the following meanings: 1. Reaction precursor liquid (ammonia water, anhydrous ethanol, tetraethyl orthosilicate, organic molecule aqueous solution), 2. Heat collecting stirrer, 3. SiO2 particles doped with organic molecules, 4. Muffle furnace, 5. Phosphorescent SiO2 nanoparticles.
[0028] Example 1: A method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence, comprising the following steps:
[0029] Ⅰ. Solution preparation: Prepare citric acid aqueous solution with a concentration of 0.1mmol / mL. Ensure that the solute in the organic molecule aqueous solution is completely dissolved before the reaction. The citric acid should be of analytical grade purity.
[0030] II. Synthesis of monodisperse SiO2 nanoparticles doped with citric acid molecules: Based on the improved Method, the prepared citric acid aqueous solution replaces the traditional Deionized water in the method. 3 mL of citric acid aqueous solution, 110 mL of anhydrous ethanol and 8 mL of ammonia water were mixed in a 250 mL beaker, and the beaker was placed in a collector magnetic stirrer and stirred for 30 minutes, and the temperature of the mixed solution was raised to 62 ° C, and then 6 mL of tetraethyl orthosilicate was added, and the stirring was continued for 130 minutes and the temperature was kept at 62 ° C, and finally a monodisperse SiO2 nanoparticle suspension doped with citric acid molecules was obtained. The suspension was repeatedly centrifuged at a centrifugal speed of 7000 rpm, and the monodisperse SiO2 nanoparticle powder doped with citric acid molecules was obtained by drying the centrifugal product.
[0031] III. Calcination to obtain phosphorescent SiO2 nanoparticles: Grind the monodisperse SiO2 nanoparticle powder doped with citric acid molecules and spread it in an alumina crucible. Place the crucible in a muffle furnace for calcination, with an initial temperature of 30°C and a heating rate of 173°C / h. After about 2 hours, the temperature is raised to 530°C, kept at 530°C for 3 hours, and finally cooled naturally to room temperature to obtain phosphorescent SiO2 powder.
[0032] The structure of the phosphorescent SiO2 nanoparticles obtained in Example 1 is as follows: Figure 2 The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results are shown in Figure 1. TME and SEM show that the prepared phosphorescent SiO2 nanoparticles have a uniform spherical structure and good monodispersity.
[0033] The optical characterization of the phosphorescent SiO2 nanoparticles obtained in Example 1 is as follows Figure 3As shown, it includes fluorescence spectrum, phosphorescence spectrum and phosphorescence decay spectrum, and the average phosphorescence lifetime is 1.5s. Under the excitation wavelength of 365nm, the fluorescence emission peak of the prepared phosphorescent SiO2 nanoparticles is located at 460nm, emitting bright blue fluorescence. The emission center of the phosphorescence spectrum is located at 507nm, indicating that the color of phosphorescence is green. In addition, by measuring the phosphorescence kinetic decay spectrum of the prepared phosphorescent SiO2 nanoparticles, it is shown that the phosphorescence lifetime is as long as 1.5s.
[0034] The optical effect of the phosphorescent SiO2 nanoparticles in Example 1 is as follows: Figure 4 As shown in the attached Figure 4 It can be clearly seen that the phosphorescent SiO2 nanoparticles emit bright fluorescence after being irradiated with ultraviolet light, and produce an optical afterglow lasting up to 15 seconds after the ultraviolet light is turned off.
[0035] Example 2: A method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence, comprising the following steps:
[0036] Ⅰ. Solution preparation: Prepare the glucose aqueous solution at a concentration of 1 mmol / mL. Ensure that the solute in the organic molecule aqueous solution is completely dissolved before the reaction. Glucose should be of analytical grade purity.
[0037] II. Synthesis of Glucose-doped Monodisperse SiO2 Nanoparticles: Based on the Improved Method, the prepared glucose aqueous solution replaces the traditional Deionized water in the method. 30mL of glucose aqueous solution, 675mL of anhydrous ethanol and 80mL of ammonia water were mixed in a 1000mL beaker, and the beaker was placed in a collector magnetic stirrer and stirred for 30min, and the temperature of the mixed solution was raised to 62°C, followed by adding 60mL of ethyl orthosilicate, and continued stirring for 130min while the temperature was maintained at 62°C, and finally a monodisperse SiO2 nanoparticle suspension doped with glucose molecules was obtained. The suspension was repeatedly centrifuged at a centrifugal speed of 7000 rpm, and monodisperse SiO2 nanoparticle powder doped with glucose molecules was obtained by drying the centrifugal product.
[0038] III. Calcination to obtain phosphorescent SiO2 nanoparticles: Grind the monodisperse SiO2 nanoparticle powder doped with glucose molecules and spread it in an alumina crucible. Place the crucible in a muffle furnace for calcination, with an initial temperature of 30°C and a heating rate of 173°C / h. After about 2 hours, the temperature is raised to 530°C, kept at 530°C for 3 hours, and finally cooled naturally to room temperature to obtain phosphorescent SiO2 powder. About 35g of the powder can be prepared at one time.
[0039] Example 3: A method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence, comprising the following steps:
[0040] Ⅰ. Solution preparation: Prepare the Rhodamine B aqueous solution at a concentration of 0.1 mmol / mL. Ensure that the solute in the organic molecule aqueous solution is completely dissolved before the reaction. Rhodamine B is of analytical grade purity.
[0041] II. Synthesis of monodisperse SiO2 nanoparticles doped with rhodamine B molecules: Based on the improved Method, the prepared Rhodamine B aqueous solution replaces the traditional Deionized water in the method. 3mL of rhodamine B aqueous solution, 110mL of anhydrous ethanol and 8mL of ammonia water were mixed in a 250mL beaker, and the beaker was placed in a collector magnetic stirrer and stirred for 30min, and the temperature of the mixed solution was raised to 62°C, and then 6mL of ethyl orthosilicate was added, and the stirring was continued for 130min and the temperature was kept at 62°C, and finally a monodisperse SiO2 nanoparticle suspension doped with rhodamine B molecules was obtained. The suspension was repeatedly centrifuged at a centrifugal speed of 7000 rpm, and the monodisperse SiO2 nanoparticle powder doped with rhodamine B molecules was obtained by drying the centrifugal product.
[0042] III. Calcination to obtain phosphorescent SiO2 nanoparticles: The monodispersed SiO2 nanoparticle powder doped with rhodamine B molecules was ground and spread flat in an alumina crucible. The crucible was placed in a muffle furnace for calcination, with an initial temperature of 30°C and a heating rate of 173°C / h. The temperature was raised to 530°C after about 2h, kept at 530°C for 3h, and finally cooled naturally to room temperature to obtain phosphorescent SiO2 powder.
[0043] The above embodiments are only used to explain the inventive concept of the present invention, rather than to limit the protection of the rights of the present invention. Any non-substantial changes to the present invention using this concept shall fall within the protection scope of the present invention.
Claims
1. A method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence, characterized in that: Using improved The method is to replace the traditional reaction precursor deionized water with a citric acid organic molecule aqueous solution to synthesize monodisperse SiO2 nanoparticles, and to prepare monodisperse SiO2 particles with bright fluorescence and ultra-long phosphorescence by high-temperature calcination of the synthesized organic molecule-doped SiO2 nanoparticles. The specific steps are as follows: The first step is to prepare the organic small molecule solution: The second step is to synthesize monodisperse SiO2 nanoparticles doped with organic small molecules: The third step is to purify SiO2 particles: The fourth step is high-temperature calcination to prepare phosphorescent SiO2 nanoparticles.
2. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 1, characterized in that: In the first step, a citric acid aqueous solution is prepared, wherein the concentration of the citric acid organic molecule aqueous solution is 0.075-0.15 mmol / mL.
3. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 2, characterized in that: In addition to citric acid, the solute in the organic molecule aqueous solution can also be replaced by glucose, melamine, urea, tartaric acid, terephthalic acid, ascorbic acid or coumarin; in addition, the solute can be replaced by fluorescent dyes, rhodamine B, rhodamine 6G, quinine sulfate or sulforhodamine B, wherein the concentration of the dye molecule aqueous solution is 0.1-1mmol / L, and it is ensured that the solute in the organic molecule aqueous solution is completely dissolved before the reaction.
4. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 1, characterized in that: In the second step, monodisperse SiO2 nanoparticles were prepared based on a modified Method, the citric acid aqueous solution prepared in the first step replaces the traditional Deionized water in the method.
5. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 4, characterized in that: Specific steps: Mix 5-6mL of citric acid aqueous solution, 150-230mL of anhydrous ethanol and 15-18mL of ammonia water in a 500mL beaker. The capacity of the beaker can be selected according to the actual volume of the reaction liquid. Place the beaker in the collector magnetic stirrer and stir for 20-40min, and raise the temperature of the mixed solution to 60-65°C. Then add 11-12mL of tetraethyl orthosilicate and 10-15mL of anhydrous ethanol mixture, continue stirring for 80-130min and keep the temperature at 60-65°C, and finally obtain a monodisperse SiO2 nanoparticle suspension doped with organic small molecules.
6. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 5, characterized in that: The ammonia solution is of analytical grade with an ammonia content of 25%; the tetraethyl orthosilicate is of analytical grade with a purity of 98%. During the preparation process, a sealing film is used to seal the mouth of the beaker to prevent the solution from volatilizing during the reaction. The liquid level of water in the collector magnetic stirrer must be higher than the liquid level of the precursor liquid in the beaker to ensure that the precursor liquid is heated evenly during the reaction. In industrial production, the proportion of the reaction solution can be proportionally enlarged, but the reaction temperature and reaction time remain fixed.
7. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 1, characterized in that: In the third step, the monodisperse SiO2 nanoparticle suspension obtained in the second step is subjected to multiple centrifugal purification. The suspension is placed in a 50mL centrifuge tube and centrifuged at 6000-7000 rpm for 10-15 min. The supernatant after centrifugation is poured out, and the white SiO2 precipitate at the bottom is collected. The solid is then redispersed in 100-200mL ethanol and centrifuged again at 6000-7000 rpm for 10-15 min. The product after centrifugation is then dispersed in ultrapure water and the centrifugation process is repeated. Finally, the obtained white SiO2 precipitate is dried in a 40-60°C forced air drying oven to obtain a white SiO2 solid.
8. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 1, characterized in that: In the fourth step, the SiO2 solid obtained in the third step is ground into powder with an agate mortar and spread evenly in an alumina crucible, and the crucible is placed in a muffle furnace for calcination. The initial temperature is 20-30°C (room temperature), and the heating rate is 170-272°C / h. After about 2-3h, the temperature is raised to 530-575°C, and it is kept at 530-575°C for 2-3h. Finally, it is naturally cooled to room temperature to obtain phosphorescent SiO2 powder.
9. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 8, characterized in that: The specification of the alumina crucible is 50 mm×25 mm. The appropriate specification is selected according to the amount of reaction. The SiO2 powder is placed in the alumina crucible and covered with a crucible of the same specification to prevent the sample from being contaminated.
10. The method for large-scale preparation of monodisperse SiO2 particles with ultra-long phosphorescence according to claim 9, characterized in that: In addition to the alumina crucible, a quartz crucible can also be used instead. In industrial production, the size of the alumina crucible can be selected according to the output of SiO2 solid in the third step.