A kind of phosphor and its preparation method and application

Abstract

The present invention relates to the technical field of inorganic luminescent materials, and in particular to a phosphor, a preparation method thereof, and an application thereof. The present invention adopts a method combining a coprecipitation method and a calcination method to synthesize a MgAl2O4:xEu sample. Fluorescence spectrum analysis shows that there are multiple defect centers in the MgAl2O4 matrix, which can emit blue-white light. The MgAl2O4 matrix itself has blue-white light emission and a short-term afterglow phenomenon. By changing the red luminescent center Eu 3+ The doping concentration realizes the change of the luminescent color of the fluorescent material from blue-white to pink-purple and finally to red, achieving the purpose of regulating the luminescent color.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic luminescent materials, and in particular to a phosphor and a preparation method and application thereof. Background Art

[0002] Inorganic luminescent materials have been extensively researched due to their exceptional properties, including high luminescence efficiency and excellent stability. Rare earth-doped luminescent materials, in particular, offer rich colors, high luminescence efficiency, and stable properties, playing a vital role in agriculture, industry, and biology. Luminescent materials are also finding applications in emerging fields such as optical temperature measurement, biosensing, and anti-counterfeiting security.

[0003] With the development of society and the needs of people, anti-counterfeiting encryption has attracted increasing attention in recent years. Researchers are constantly developing new technologies, and new information security technologies are also being developed and applied to anti-counterfeiting, such as plasma security tags, magnetic response tags, and fluorescent mapping technology. These new anti-counterfeiting encryption technologies mainly involve disciplines such as physics, chemistry, computer science, and optics. Fluorescent anti-counterfeiting encryption technology, a type of optical anti-counterfeiting encryption, is simple to process, difficult to imitate, and economical, making it of great research value.

[0004] Currently, color control of luminescent materials primarily utilizes the principle of three primary colors. This involves selecting two or more materials with different luminescent colors and adjusting the ratio of these materials to achieve different colors, thereby meeting the demand for different colors. However, the use of multiple luminescent materials increases costs and reduces the luminous efficiency of the materials. Furthermore, the uneven mixing of multiple luminescent materials during the blending process can also affect the color purity of the multicolor luminescent material. Furthermore, existing preparations of inorganic fluorescent materials mostly utilize high-temperature solid-phase methods. However, the inorganic materials obtained by direct calcination under high temperature conditions have relatively large particle sizes, reaching the micron level. In practical applications, these particles are coarse and have poor light resistance. Summary of the Invention

[0005] In view of the above shortcomings of the prior art, the present invention aims to provide a MgAl2O4:xEu phosphor and its preparation method. The present invention adopts a coprecipitation-calcination method to first obtain a precursor with relatively uniform size by coprecipitation, and then obtain a phosphor material with a particle size of about 20-30 nanometers by calcination. The MgAl2O4 matrix prepared by this method has a blue-white light emission and a short-term afterglow phenomenon. By changing the red luminescent center Eu 3+ The doping concentration enables the luminescent material to change its luminous color from blue to blue-white, then to pink-purple and finally to red, achieving the purpose of regulating the luminous color.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The first object of the present invention is to provide a phosphor having a chemical formula of MgAl2O4:xEu, wherein x is the molar ratio of Eu:Mg, and x=0-10%.

[0008] A second object of the present invention is to provide a method for preparing the phosphor described above, comprising the following steps:

[0009] (1) Weighing a soluble magnesium salt, a soluble europium salt, and a soluble aluminum salt according to the ratio of elements in MgAl2O4:xEu, where x is the molar ratio of Eu:Mg, and x = 0 to 10%;

[0010] (2) dissolving polyvinyl pyrrolidone and cetyltrimethylammonium bromide in water, adding the soluble magnesium salt weighed in step (1), stirring to form a solution, and then adding the soluble europium salt weighed in step (1) to obtain a mixed solution;

[0011] (3) dissolving the soluble aluminum salt weighed in step (1) in water to form an aluminum-containing solution, and adding the aluminum-containing solution to the mixed solution of step (2) with stirring;

[0012] (4) adjusting the pH of the solution obtained in step (3) to 9-10, stirring to obtain a precipitate, and allowing to stand at room temperature;

[0013] (5) The solution after standing in step (4) is centrifuged and dried to obtain a precursor, the precursor is ground, and then calcined to obtain MgAl2O4:xEu phosphor.

[0014] Preferably, in step (1), the soluble magnesium salt is Mg(NO3)2·6H2O, the soluble europium salt is Eu(NO3)3·6H2O, and the soluble aluminum salt is Al(NO3)3·9H2O.

[0015] Preferably, in step (2), the mass ratio of polyvinyl pyrrolidone to hexadecyltrimethylammonium bromide is 5:2, the mass volume ratio of polyvinyl pyrrolidone to water is 0.5 g:30 mL, and the mass ratio of soluble magnesium salt to polyvinyl pyrrolidone is 1.28:0.5.

[0016] Preferably, in step (4), stirring is first continued for 0.5 to 2 hours to obtain a precipitate, and then stirring is continued for 36 hours at room temperature, and the standing time at room temperature is 24 to 36 hours.

[0017] Preferably, the reagent used to adjust the pH of the solution in step (4) is NH3·H2O.

[0018] Preferably, in step (5), the drying temperature is 60-80° C. and the drying time is 4-8 hours.

[0019] Preferably, a two-step calcination procedure is adopted in step (5), specifically, first reacting at 250° C. for 2 h, and then reacting at 600° C. for 4 h.

[0020] The third object of the present invention is to provide an application of the above-mentioned phosphor in the field of anti-counterfeiting security.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention adopts the coprecipitation method and calcination method to synthesize MgAl2O4:xEu samples. Fluorescence spectrum analysis shows that there are multiple defect centers in the MgAl2O4 matrix, which can emit blue-white light. The MgAl2O4 matrix itself has blue-white light emission and a short-term afterglow phenomenon, and Eu 3+ It can emit high-efficiency red, and the combination of the two can change the color according to the hue relationship. By changing Eu 3+ By adjusting the doping concentration, the luminescent color of the fluorescent material changes from blue to blue-white, then to pink-purple and finally to red, achieving the purpose of regulating the luminescent color. After the MgAl2O4:xEu sample is irradiated with ultraviolet light, the sample emits a green afterglow that lasts for 15 seconds after the ultraviolet light is turned off. This material has great development potential in the field of anti-counterfeiting security.

[0023] 2. The preparation process of the present invention first adopts the room temperature coprecipitation method and then calcined at 600 ° C to obtain an inorganic luminescent material with a size of only 20-30 nanometers and good dispersion. The present invention only uses one luminescent material, and by regulating the red luminescent center Eu in the preparation process 3+ The concentration of inorganic luminescent materials can be adjusted from blue to red.

[0024] 3. By utilizing the color-changing luminescence and short-time afterglow of the MgAl2O4:xEu material of the present invention to encrypt some documents and labels, the possibility of information theft can be eliminated and the level of information anti-counterfeiting can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 (a) X-ray diffraction pattern of MgAl2O4:xEu, (b) scanning electron micrograph of MgAl2O4 sample, (c) scanning electron micrograph of MgAl2O4:4%Eu sample of the present invention;

[0026] Figure 2 (a) Emission spectrum and (b) excitation spectrum of the MgAl2O4:xEu sample of the present invention;

[0027] Figure 3(a) CIE diagram of the MgAl2O4:xEu sample of the present invention, (b) a photograph of the MgAl2O4:xEu sample taken under an ultraviolet lamp (365nm);

[0028] Figure 4 These are photographs of the fluorescent thin films of the MgAl2O4:xEu sample of the present invention under sunlight (a) and 365nm ultraviolet light (b) (the Eu contents of the samples used to make patterns I, heart shape, I, M, U, and T are 0%, 0.1%, 0.5%, 1%, 4%, and 10%, respectively); (b) photograph of the fluorescent thin film of the MgAl2O4:xEu sample under 365nm ultraviolet light; and (c) photograph of the afterglow fluorescence of the letters I, heart shape, I, M, U, and T after the ultraviolet light is turned off. DETAILED DESCRIPTION

[0029] The following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

[0030] Example 1

[0031] A method for preparing MgAl2O4 phosphor comprises the following steps:

[0032] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is evenly dispersed, add 0.005 mol of Mg(NO3)2·6H2O to the solution and stir to form a magnesium nitrate solution.

[0033] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until the mixture is completely mixed to form an aluminum nitrate solution. Then, add the aluminum nitrate solution to the magnesium nitrate solution in step (1) and stir slowly for 1 h.

[0034] (3) NH3·H2O was added to adjust the solution pH to 9, and the mixture was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h;

[0035] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first at 250°C for 2 hours and then at 600°C for 4 hours to obtain the MgAl2O4 sample.

[0036] Example 2

[0037] A method for preparing MgAl2O4:0.1%Eu phosphor comprises the following steps:

[0038] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is uniformly dispersed, 0.005 mol of Mg(NO3)2·6H2O is added to the solution and stirred to form a magnesium nitrate solution. Then, a Eu(NO3)3·6H2O solution having a molar ratio of 0.1% to the Mg(NO3)2·6H2O solution is added to obtain a mixed solution.

[0039] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until it is completely dissolved to form an aluminum nitrate solution, then add the aluminum nitrate solution to the mixed solution in step (1) and slowly stir for 1 h;

[0040] (3) NH3·H2O was added to adjust the solution pH to 10, and the mixture was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h.

[0041] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first reacting at 250°C for 2 hours and then reacting at 600°C for 4 hours to obtain the MgAl2O4:0.1%Eu sample.

[0042] Example 3

[0043] A method for preparing MgAl2O4:0.5%Eu phosphor comprises the following steps:

[0044] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is uniformly dispersed, 0.005 mol of Mg(NO3)2·6H2O is added to the solution and stirred to form a magnesium nitrate solution. Then, a Eu(NO3)3·6H2O solution having a molar ratio of 0.5% to the Mg(NO3)2·6H2O solution is added to obtain a mixed solution.

[0045] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until it is completely dissolved to form an aluminum nitrate solution, then add the aluminum nitrate solution to the mixed solution in step (1) and slowly stir for 1 h;

[0046] (3) NH3·H2O was added to adjust the solution pH to 9, and the mixture was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h;

[0047] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tube furnace using a two-step calcination program, first reacting at 250°C for 2 hours and then reacting at 600°C for 4 hours to obtain the MgAl2O4:0.5%Eu sample.

[0048] Example 4

[0049] A method for preparing MgAl2O4:1%Eu phosphor comprises the following steps:

[0050] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is uniformly dispersed, 0.005 mol of Mg(NO3)2·6H2O is added to the solution and stirred to form a magnesium nitrate solution. Then, a Eu(NO3)3·6H2O solution having a molar ratio of 1% to the Mg(NO3)2·6H2O solution is added to obtain a mixed solution.

[0051] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until it is completely dissolved to form an aluminum nitrate solution, then add the aluminum nitrate solution to the mixed solution in step (1) and slowly stir for 1 h;

[0052] (3) NH3·H2O was added to adjust the solution pH to 10, and the mixture was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h.

[0053] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first reacting at 250°C for 2 hours and then reacting at 600°C for 4 hours to obtain the MgAl2O4:1%Eu sample.

[0054] Example 5

[0055] A method for preparing MgAl2O4:4%Eu phosphor comprises the following steps:

[0056] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is uniformly dispersed, 0.005 mol of Mg(NO3)2·6H2O is added to the solution and stirred to form a magnesium nitrate solution. Then, a Eu(NO3)3·6H2O solution having a molar ratio of 4% to the Mg(NO3)2·6H2O solution is added to obtain a mixed solution.

[0057] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until it is completely dissolved to form an aluminum nitrate solution, then add the aluminum nitrate solution to the mixed solution in step (1) and slowly stir for 1 h;

[0058] (3) NH3·H2O was added to adjust the solution to pH 9, and the solution was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h;

[0059] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first reacting at 250°C for 2 hours and then reacting at 600°C for 4 hours to obtain the MgAl2O4:4%Eu sample.

[0060] Example 6

[0061] A method for preparing MgAl2O4:10%Eu phosphor comprises the following steps:

[0062] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is uniformly dispersed, 0.005 mol of Mg(NO3)2·6H2O is added to the solution and stirred to form a magnesium nitrate solution. Then, a Eu(NO3)3·6H2O solution having a molar ratio of 10% of the Mg(NO3)2·6H2O solution is added to obtain a mixed solution.

[0063] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until it is completely dissolved to form an aluminum nitrate solution. Then, add the aluminum nitrate solution to the mixed solution of step (1) and stir slowly for 1 h.

[0064] (3) NH3·H2O was added to adjust the solution to a pH of 10, and the solution was stirred continuously for 30 min to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 24 h.

[0065] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 60°C for 4 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first reacting at 250°C for 2 hours and then reacting at 600°C for 4 hours to obtain the MgAl2O4:10%Eu sample.

[0066] Example 7

[0067] A method for preparing MgAl2O4 phosphor comprises the following steps:

[0068] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is evenly dispersed, add 0.005 mol of Mg(NO3)2·6H2O to the solution and stir to form a magnesium nitrate solution.

[0069] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until the mixture is completely mixed to form an aluminum nitrate solution. Then, add the aluminum nitrate solution to the magnesium nitrate solution in step (1) and stir slowly for 1 h.

[0070] (3) NH3·H2O was added to adjust the solution pH to 9, and the mixture was stirred continuously for 1 h to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 30 h.

[0071] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 80°C for 8 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first at 250°C for 2 hours and then at 600°C for 4 hours to obtain the MgAl2O4 sample.

[0072] Example 8

[0073] A method for preparing MgAl2O4 phosphor comprises the following steps:

[0074] (1) Weigh 0.5 g of polyvinylpyrrolidone and 0.2 g of hexadecyltrimethylammonium bromide and dissolve them in 30 mL of distilled water. After the mixture is evenly dispersed, add 0.005 mol of Mg(NO3)2·6H2O to the solution and stir to form a magnesium nitrate solution.

[0075] (2) Weigh 0.01 mol Al(NO3)3·9H2O in 20 mL of distilled water and stir for 30 min until the mixture is completely mixed to form an aluminum nitrate solution. Then, add the aluminum nitrate solution to the magnesium nitrate solution in step (1) and stir slowly for 1 h.

[0076] (3) NH3·H2O was added to adjust the solution pH to 9, and the mixture was stirred continuously for 1 h to obtain a precipitate. The mixed solution was slowly stirred at room temperature for 36 h, and then allowed to stand at room temperature for 36 h;

[0077] (4) Finally, the solution after standing in step (3) was centrifuged and dried at 70°C for 6 hours to obtain a powdered precursor. The dried sample was ground into powder and calcined in a tubular furnace using a two-step calcination program, first at 250°C for 2 hours and then at 600°C for 4 hours to obtain the MgAl2O4 sample.

[0078] Application Examples

[0079] Polydimethylsiloxane (PDMS) is an organic elastic material with high transparency, high chemical stability, and strong hydrophobicity. Mixing it with the phosphor prepared in Examples 1-6 yields a luminescent composite elastomer. PDMS and the curing agent Dow Corning SYLGARD 184 are mixed in a 10:1 mass ratio in a Petri dish. MgAl2O4:xEu phosphor (with a 1:1 mass ratio to PDMS) is then added to the dish and stirred thoroughly. Finally, the dish is placed in an oven at 60°C for 5 hours. Once cured, it is removed to produce a fluorescent film.

[0080] Result Analysis

[0081] Sample phase and morphology analysis

[0082] The phase composition of MgAl2O4:xEu samples was characterized and analyzed by X-ray powder diffraction (XRD). Figure 1 It can be clearly seen that the XRD diffraction peaks of the prepared samples are completely consistent with the diffraction peak positions of the MgAl2O4 standard card (JCPDS: 96-900-2059, Fd-3m space group), and no other impurity peaks are observed. The 2θ peaks of 19.3°, 31.8°, 37.4°, 45.5°, 56.6°, 60.4°, 66.4° and 78.8° correspond to the (111), (220), (311), (400), (422), (511), (440) and (533) crystal planes of MgAl2O4, respectively. 3+ The XRD diffraction peaks of the MgAl2O4:xEu sample obtained by ion doping are consistent with the diffraction peaks of the MgAl2O4 standard card, and no impurity phase peaks appear. Figure 1 (b) is the SEM image of MgAl2O4 sample, compared with Figure 1 (b) and (c) show that all samples are nanospheres with uniform morphology and a diameter of 20-30 nm. 3+ Ion doping does not cause changes in the crystal structure and morphology of MgAl2O4.

[0083] Color coordinates are an indispensable indicator for evaluating the performance of phosphors. In order to better express the multi-color luminescence of MgAl2O4:xEu, the CIE chromaticity diagram calculated based on the fluorescence spectra of MgAl2O4:xEu (x = 0%, 0.1%, 0.5%, 1%, 4% and 10%) phosphors at an excitation wavelength of 274nm is shown in the figure below. Figure 3 As shown in the chromaticity diagram, the color coordinates of the pure phase of MgAl2O4 are located in the blue light region, and as Eu 3+With the increase of doping concentration, the color coordinates change from the blue area to the blue-white area, then to the pink-white area, and finally to the red area. 3+ The doping content of Eu can achieve color changes within a certain range and realize the modulation of luminescent color. 3+ MgAl2O4:xEu samples with the following doping concentrations were prepared: Figure 4 The letters and heart-shaped patterns shown in the fluorescent film correspond to Eu 3+ The ion doping concentration is 0%, 0.1%, 0.5%, 1%, 4% and 10%. Under 365nm ultraviolet light, it can be observed that as Eu 3+ As the doping concentration increases, the film color changes to different colors, namely blue, blue-white, pink-purple, pink and red. Figure 4 The following are photos of the gradual attenuation of the brightness of the film composed of letters and heart-shaped patterns over time after the UV light is turned off. 3+ The doped samples no longer show different colors, but are uniformly green in color, with an afterglow duration of 15 seconds. By using the color-changing luminescence and short afterglow of the MgAl2O4:xEu material to encrypt some files and labels, the possibility of information theft can be eliminated and the level of information anti-counterfeiting can be improved.

[0084] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a phosphor, characterized in that: The chemical formula of the phosphor is MgAl2O4: xEu 3+ , x is the molar ratio of Eu:Mg, x = 0~10%; The method for preparing the phosphor comprises the following steps: (1) According to MgAl2O4: xEu 3+ The proportion of elements in the mixture is: Weigh the soluble magnesium salt, soluble europium salt and soluble aluminum salt, where x is the molar ratio of Eu:Mg, and x = 0~10%; (2) dissolving polyvinyl pyrrolidone and hexadecyltrimethylammonium bromide in water, adding the soluble magnesium salt weighed in step (1), stirring to form a solution, and then adding the soluble europium salt weighed in step (1) to obtain a mixed solution; (3) dissolving the soluble aluminum salt weighed in step (1) in water to form an aluminum salt solution, and adding the aluminum salt solution to the mixed solution in step (2) with stirring; (4) adjusting the pH of the solution obtained in step (3) to 9-10, stirring to obtain a precipitate, and allowing to stand at room temperature; (5) The solution after standing in step (4) is centrifuged and dried to obtain a precursor, which is then ground and calcined to obtain MgAl2O4: xEu 3+ phosphors; In step (4), the mixture is first stirred continuously for 0.5 to 2 h to obtain a precipitate, and then stirred at room temperature for 36 h, and allowed to stand at room temperature for 24 to 36 h; In step (5), a two-step calcination procedure was adopted, specifically, first reacting at 250 °C for 2 h and then reacting at 600 °C for 4 h.

2. The method for preparing the phosphor according to claim 1, wherein: In step (1), the soluble magnesium salt is Mg(NO3)2·6H2O, the soluble europium salt is Eu(NO3)3·6H2O, and the soluble aluminum salt is Al(NO3)3·9H2O.

3. The method for preparing the phosphor according to claim 1, wherein: In step (2), the mass ratio of polyvinyl pyrrolidone to hexadecyltrimethylammonium bromide is 5:2, the volume ratio of polyvinyl pyrrolidone to water is 0.5 g:30 mL, and the mass ratio of soluble magnesium salt to polyvinyl pyrrolidone is 1.28:0.

5.

4. The method for preparing the phosphor according to claim 1, wherein: The reagent used to adjust the pH of the solution in step (4) is NH3·H2O.

5. The method for preparing phosphor according to claim 1, wherein: In step (5), the drying temperature is 60-80°C and the drying time is 4-8 h.

6. Use of the phosphor prepared by the preparation method according to claim 1 in the field of anti-counterfeiting security.

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