Preparation method for surface plasmon enhanced mn 4+-doped double perovskite fluorescent powder and use of fluorescent powder

Abstract

Disclosed in the present invention is a preparation method for a surface plasmon enhanced Mn4+-doped double perovskite fluorescent powder, which preparation method comprises: S1, selecting specific A, B' and B'' source compounds, mixing same according to a stoichiometric ratio, adding zirconium oxide balls into a ball milling tank, subjecting the mixture to planetary ball milling for 3-8 hours, then placing the mixture into an alumina crucible, sintering same at 900-1300°C for 6-15 hours to obtain a matrix, cooling the matrix, and subjecting same to a particle size treatment and XRD detection; S2, selecting an Mn4+-containing compound, and subjecting same having a concentration of 0.1-5 mol% and the matrix to ball milling for 2-6 hours; and S3, subjecting a metal salt solution and the material obtained in the previous step to an ultrasonic treatment, so as to achieve a metal nano treatment. The luminous efficiency of the fluorescent powder of the present invention is significantly improved; the intensity can be improved by 30-50% compared with that of a traditional fluorescent powder; and color regulation and control are accurate, such that multicolor fluorescence emission can be achieved. The color saturation and luminous efficiency can be improved when the fluorescent powder is applied to a display technology; the color rendering index and luminous efficiency can be improved when the fluorescent powder is used for illumination; and the anti-counterfeiting effect in the anti-counterfeiting field is enhanced. In addition, the fluorescent powder has good chemical stability, and the preparation thereof is easy to control, which are beneficial for industrial production and multi-field application expansion.

Description

A surface plasmon-enhanced Mn 4+ Preparation methods and applications of doped double perovskite phosphors Technical Field

[0001] This invention relates to the field of double perovskite phosphor preparation technology, specifically to a surface plasmon-enhanced Mn 4+ Preparation method and application of doped double perovskite phosphors. Background Technology

[0002] With the rapid development of technology, fluorescent materials play a vital role in many fields, such as display technology, lighting engineering, and anti-counterfeiting labels. In these applications, the requirements for the luminescent performance of fluorescent materials are becoming increasingly stringent.

[0003] Traditional phosphors have limitations in terms of luminous efficiency and color control. For example, some commonly used fluorescent materials are prone to concentration quenching when doped at high concentrations, leading to a decrease in luminous intensity, which greatly limits their application in scenarios requiring high brightness. Moreover, traditional phosphors have relatively limited color emission, making it difficult to achieve multi-color emission through simple methods, and thus failing to meet complex requirements in fields such as fluorescent anti-counterfeiting where color diversity is crucial.

[0004] In the field of display technology, existing fluorescent materials struggle to simultaneously achieve high color saturation and high luminous efficiency. As consumers' demands for display performance continue to rise, such as in high-resolution liquid crystal displays, organic light-emitting diode displays, and quantum dot displays, fluorescent materials are required to emit more vibrant and brighter light under blue or ultraviolet light excitation to improve image quality and visual experience. However, traditional phosphors are unable to meet this requirement.

[0005] The lighting sector also faces challenges. For white LED lighting devices, the current fluorescent materials, when combined with blue or ultraviolet chips, have limited room for improvement in color rendering index (CRI) and luminous efficacy. A low CRI leads to color distortion of objects in the lighting environment, while low luminous efficacy increases energy consumption, which is inconsistent with the development trend of energy conservation and environmental protection.

[0006] Furthermore, with the continuous upgrading of anti-counterfeiting technology, the requirements for fluorescent anti-counterfeiting materials are also becoming increasingly stringent. Traditional fluorescent anti-counterfeiting materials are easily counterfeited, and their fluorescent properties are not unique enough and difficult to control, failing to meet the demands of modern high-security anti-counterfeiting.

[0007] Surface plasmons are electromagnetic oscillations present on the surface of metallic nanostructures that can interact with fluorescent materials to enhance fluorescence emission. Based on this, a surface plasmon-enhanced Mn... 4+The development of doped double perovskite phosphors is of great significance. The double perovskite structure exhibits excellent chemical stability and physical properties. Mn 4+ Doping can endow phosphors with specific luminescent properties. Combined with the introduction of surface plasmon effects by metal nanoparticles, it is expected to overcome many shortcomings of traditional phosphors, achieve performance breakthroughs in multiple fields, and meet the urgent needs of modern technology for high-performance fluorescent materials. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides a surface plasmon-enhanced Mn 4+ A method for preparing doped double perovskite phosphors.

[0010] (II) Technical Solution

[0011] A surface plasmon-enhanced Mn 4+ The preparation method of doped double perovskite phosphor includes the following steps: S1: raw material pretreatment, selecting alkali metal or alkaline earth metal carbonates or nitrates as source compounds A, monovalent metal halides or nitrates as source compounds B', and pentavalent metal oxides or halides as source compounds B”. Grinding each raw material, controlling the particle size of the ground raw material to be 10-50 μm, and then placing them in a vacuum drying oven at 60-80℃ for 2-4 hours to remove moisture and impurities.

[0012] S2: Synthesis of the double perovskite matrix. The treated A, B', and B” source compounds were precisely weighed according to the stoichiometric ratio of the double perovskite structure A2B'B”O6 and placed in a ball mill jar. Zirconia balls were added as the grinding medium at a ball-to-material ratio of 5:1-10:1. A planetary ball mill was used for milling for 3-8 hours at a speed of 300-800 rpm to obtain a uniformly mixed raw material powder. This powder was transferred to an alumina crucible and sintered in a high-temperature furnace at 900-1300℃ for 6-15 hours in an air or oxygen atmosphere with a heating rate controlled at 5-10℃ / min to synthesize the double perovskite matrix material. After natural cooling to room temperature, the synthesized matrix material was ground again to a particle size of 20-100 μm.

[0013] S3: Mn 4+ For doping preparation, permanganate or manganese oxide is selected as the Mn-containing substrate. 4+ The compound was combined with the synthesized double perovskite matrix material according to the Mn... 4+The target doping concentration (0.1-5 mol%) was weighed and then placed in a ball mill jar. Zirconia balls were added at a ball-to-material ratio of 4:1-8:1. The mixture was then ball-milled using a planetary ball mill for 2-6 hours at a speed of 200-600 rpm. 4+ The compound is uniformly dispersed in the double perovskite matrix material.

[0014] S4:Mn 4+ After doping and sintering, the ball-milled mixture is transferred to an alumina crucible and placed in a high-temperature furnace for secondary sintering at 800-1100℃ for 3-10 hours, with a heating rate controlled at 3-8℃ / min, to allow the Mn to undergo doping and sintering. 4+ Doping into the double perovskite matrix lattice yields Mn 4+ The doped perovskite material is sintered, then naturally cooled to room temperature, and then ground to a particle size of 30-120 μm.

[0015] S5: Introduction of metal nanoparticles, using in-situ synthesis in Mn 4+ Metal nanoparticles are introduced onto the surface of doped double perovskite materials. A solution of a metal salt (gold, silver, or aluminum) is mixed with Mn... 4+ The doped double perovskite material is uniformly mixed with a metal salt solution at a concentration of 0.05-0.5 mol / L. Ultrasonic dispersion is used during mixing at a frequency of 20-40 kHz for 10-30 minutes. The mixture is then heat-treated at 150-300℃ for 1-4 hours with continuous stirring at a speed of 100-300 rpm. This process forms metal nanoparticles with a diameter of 20-80 nm on the material surface, resulting in surface plasmon-enhanced MnO2. 4+ Doped double perovskite phosphor.

[0016] Furthermore, in step S1, the vacuum level of the vacuum drying oven is maintained at 0.05-0.1 MPa.

[0017] In step S2, the grinding jar of the planetary ball mill is made of stainless steel or hard alloy, and the grinding process is paused for 5-10 minutes every 1-2 hours to prevent the material from overheating.

[0018] In step S3, the milling jar must be cleaned with anhydrous ethanol and dried before use to avoid contamination by impurities.

[0019] In step S4, the furnace lining of the high-temperature furnace is made of high-purity alumina or mullite, which has good high-temperature resistance and heat insulation properties.

[0020] In step S5, the metal salt solution is prepared using deionized water or anhydrous ethanol as the solvent and must be filtered through a 0.2-0.5 μm filter membrane to remove impurities.

[0021] Furthermore, in step S2, the heating element of the high-temperature furnace is a silicon molybdenum rod or a graphite rod, which enables precise temperature control.

[0022] In step S3, the planetary ball mill is cooled by water or air to ensure stable equipment temperature during the ball milling process.

[0023] In step S4, the cooling process after secondary sintering can be carried out by furnace cooling or cooling under inert gas protection to reduce material oxidation or other impurities.

[0024] In step S5, the heat treatment equipment is a constant temperature oven or tube furnace with stirring and temperature control functions, which can precisely control the reaction conditions.

[0025] Furthermore, in step S2, the crystal structure of the synthesized double perovskite matrix material is detected by X-ray diffraction (XRD) to ensure that it conforms to the characteristics of double perovskite structure. The scanning step size of XRD detection is 0.02-0.05°, and the scanning speed is 1-5° / minute.

[0026] In step S4, Mn 4+ Mn doped double perovskite materials 4+ The doping concentration was accurately determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), with the measurement error controlled within ±0.05 mol%.

[0027] In step S5, the particle size and distribution of the metal nanoparticles are observed and analyzed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The resolution of SEM is 1-5 nm, and the resolution of TEM is 0.1-1 nm.

[0028] Furthermore, after step S5, the obtained phosphor undergoes post-treatment. It is first washed alternately with deionized water and anhydrous ethanol 3-5 times, followed by centrifugation at 3000-6000 rpm for 5-15 minutes after each wash. Then, the washed phosphor is vacuum-dried at 50-70℃ for 2-4 hours at a vacuum degree of 0.08-0.12 MPa. Finally, it is passed through a 200-500 mesh sieve to obtain uniform and pure surface plasmon-enhanced Mn. 4+ Doped double perovskite phosphor.

[0029] Furthermore, throughout the entire preparation process, all operations are carried out in a dust-free, constant temperature (20-25℃), and constant humidity (40%-60%) environment to reduce the impact of external factors on material quality.

[0030] Furthermore, during the high-temperature sintering process in steps S2 and S4, an intelligent temperature control system is adopted, which can automatically adjust the heating power according to the preset temperature curve, with a temperature control accuracy of ±1℃.

[0031] Furthermore, a surface plasmon-enhanced Mn 4+ The application of doped double perovskite phosphors includes: applying the phosphors to the preparation of fluorescent anti-counterfeiting labels; controlling the fluorescence emission wavelength and intensity of the fluorescent anti-counterfeiting label under specific excitation light by adjusting the doping concentration of the phosphors and the content of metal nanoparticles to achieve multi-color fluorescent anti-counterfeiting effects; the mass fraction of the phosphors in the anti-counterfeiting label material is 5-30%. After uniformly mixing the phosphors with organic resins (such as epoxy resins and polyurethane resins), fluorescent anti-counterfeiting labels are prepared using processes such as coating, printing, or injection molding. In the printing process, flexographic or screen printing plates are used, the printing pressure is 0.1-0.5 MPa, and the printing speed is 1-5 m / s. In the injection molding process, the injection temperature is 150-250℃, the injection pressure is 50-150 MPa, and the mold temperature is 30-80℃.

[0032] (III) Beneficial Technical Effects

[0033] In terms of luminescence properties, through Mn 4+ The doping and surface plasmon resonance effect introduced by metal nanoparticles effectively improve the luminous efficiency of phosphors. Compared with traditional phosphors, their luminous intensity can be increased by 30%-50%. Under specific excitation light, they can emit brighter light, which allows them to significantly improve the brightness and color saturation of displays when applied in the field of display technology, making images more vivid and clear, and bringing users a better visual experience. For example, in organic light-emitting diode displays, they can make color reproduction more accurate, meeting the stringent image quality requirements of high-end display devices.

[0034] It performs excellently in color control, by adjusting Mn 4+ By controlling the doping concentration, content, and type of metal nanoparticles, the fluorescence emission wavelength and intensity of the phosphor can be precisely controlled, achieving multicolor fluorescence emission from the visible to near-infrared range. This multicolor fluorescence characteristic is extremely valuable in fluorescent anti-counterfeiting label applications, greatly increasing the complexity and security of anti-counterfeiting labels, effectively preventing counterfeiting, and providing reliable protection for product anti-counterfeiting traceability.

[0035] In the lighting field, when applied to white LED lighting devices, a good combination with blue or ultraviolet light chips can increase the color rendering index by 10%-20% and the luminous efficacy by 20%-30%. This not only reduces energy consumption during the lighting process, conforming to the concept of energy conservation and environmental protection, but also makes the lighting environment closer to natural sunlight, improving people's ability to distinguish the colors of objects in this environment and enhancing the quality of lighting.

[0036] From the perspective of the material's inherent properties, the double perovskite structure endows the phosphor with excellent chemical and thermal stability, enabling it to operate stably under various environmental conditions, extending its service life, and reducing maintenance costs. Moreover, the preparation method is relatively simple, easy to operate and control, which is conducive to large-scale industrial production. While reducing production costs, it can be rapidly applied to various related fields, driving technological progress in industries such as display, lighting, and anti-counterfeiting, resulting in significant economic and social benefits. Detailed Implementation

[0037] Example 1

[0038] Surface plasmon-enhanced Mn 4+ Preparation of doped double perovskite phosphors

[0039] Raw material preparation and pretreatment

[0040] Cesium carbonate (Cs₂CO₃) was selected as the A source compound, silver nitrate (AgNO₃) as the B' source compound, and antimony pentoxide (Sb₂O₅) as the B” source compound. Cs₂CO₃, AgNO₃, and Sb₂O₅ were ground separately in mortars to control the particle size to 10-30 μm. The ground materials were then placed in a vacuum drying oven and dried at 60°C and a vacuum of 0.08 MPa for 3 hours to remove moisture and impurities.

[0041] Synthesis of double perovskite matrix

[0042] The dried raw material was precisely weighed according to the stoichiometric ratio of Cs₂AgSbO₆ and placed in a stainless steel ball mill jar. Zirconia balls were added at a ball-to-material ratio of 8:1. The material was ball-milled using a planetary ball mill for 5 hours at a speed of 500 rpm. The milled powder was then transferred to an alumina crucible and placed in a high-temperature furnace for sintering at 1100℃ for 10 hours in an air atmosphere at a heating rate of 8℃ / min. After the synthesized matrix material was allowed to cool naturally to room temperature, it was further ground to a particle size of 50-80 μm. X-ray diffraction (XRD) analysis showed that its crystal structure conformed to the characteristics of a double perovskite structure, with an XRD scan step size of 0.03° and a scan speed of 3° / min.

[0043] Mn 4+ Doping preparation

[0044] Potassium permanganate (KMnO4) was chosen as the Mn-containing... 4+ The compound, according to Mn 4+The doping concentration of 2 mol% was weighed with the synthesized double perovskite matrix material. Both were placed together in a ball mill jar, and zirconia balls were added at a ball-to-material ratio of 6:1. The mixture was ball-milled using a planetary ball mill for 4 hours at a speed of 400 rpm to achieve the desired Mn content. 4+ The compound was uniformly dispersed in a double perovskite matrix material. The milling jar was cleaned with anhydrous ethanol and dried before use.

[0045] Mn 4+ Doping sintering

[0046] The ball-milled mixture was transferred to an alumina crucible and placed in a high-temperature furnace for secondary sintering at 950°C for 6 hours at a heating rate of 5°C / min, so that Mn... 4+ Doping into the double perovskite matrix lattice yields Mn 4+ Doped double perovskite material. After sintering, it was naturally cooled to room temperature and then ground to a particle size of 60-90 μm. Mn was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). 4+ The doping concentration was 1.95 mol, and the measurement error was controlled within ±0.05 mol%.

[0047] Introduction of metal nanoparticles

[0048] In situ synthesis of Mn 4+ Silver nanoparticles were introduced onto the surface of a doped double perovskite material. A silver nitrate solution (0.2 mol / L) was mixed with Mn... 4+ The doped double perovskite materials were uniformly mixed using ultrasonic dispersion at a frequency of 30 kHz for 20 minutes. The mixture was then heat-treated at 200°C for 2 hours with continuous stirring at 200 rpm. Scanning electron microscopy (SEM) revealed the formation of silver nanoparticles with a diameter of 30-60 nm on the material surface, resulting in surface plasmon-enhanced MnO2. 4+ Doped double perovskite phosphor.

[0049] Post-processing

[0050] The prepared phosphor was first washed four times alternately with deionized water and anhydrous ethanol, followed by centrifugation at 4000 rpm for 10 minutes after each wash. The washed phosphor was then vacuum-dried at 60°C for 3 hours at a vacuum degree of 0.1 MPa, and finally passed through a 300-mesh sieve to obtain a uniform and pure phosphor.

[0051] Performance Testing and Application

[0052] The prepared phosphor was tested for fluorescence performance. Under blue light (450nm) excitation, its luminescence intensity was increased by 40% compared to similar phosphors without added metal nanoparticles. When applied to the backlight of an organic light-emitting diode (OLED) display, the display's color saturation increased by 25% and luminous efficiency increased by 30%. In fluorescent anti-counterfeiting applications, by adjusting the preparation parameters, multi-color fluorescence emission from red to green was achieved under specific excitation light, resulting in significant anti-counterfeiting effects.

[0053] Example 2

[0054] Surface plasmon-enhanced Mn 4+ Preparation of doped double perovskite phosphors

[0055] Raw material preparation and pretreatment

[0056] Sodium nitrate (NaNO3) was used as the A source compound, lithium chloride (LiCl) as the B' source compound, and antimony trichloride (SbCl3) as the B” source compound. All raw materials were ground to a particle size of 20-40 μm and dried at 70 °C and a vacuum of 0.06 MPa for 2.5 hours.

[0057] Synthesis of double perovskite matrix

[0058] The raw material was weighed according to the stoichiometric ratio of Na2LiSbO6 and placed in a cemented carbide ball mill jar with a ball-to-material ratio of 7:1. The mixture was ball-milled for 6 hours at a speed of 600 rpm. It was then sintered at 1200℃ for 8 hours (oxygen atmosphere, heating rate 6℃ / min). After cooling, the material was ground to a particle size of 40-70 μm. XRD analysis showed normal structure (scan step size 0.025°, speed 2° / min).

[0059] Mn 4+ Doping preparation

[0060] Sodium manganate (Na2MnO4) was used as a Mn-containing... 4+ The compound was weighed at a doping concentration of 3 mol%, and ball-milled with the matrix for 3 hours at a speed of 300 rpm and a ball-to-material ratio of 5:1. The ball mill jar was pretreated in the same way as in Example 1.

[0061] Mn 4+ Doping sintering

[0062] Secondary sintering was carried out at 1000℃ for 4 hours (heating rate 4℃ / min). After cooling, the particle size was 50-80μm. Mn was measured by ICP-AES. 4+ The concentration was 2.98 mol%.

[0063] Introduction of metal nanoparticles

[0064] Gold nanoparticles were synthesized in situ. The material was mixed with chloroauric acid solution (concentration 0.3 mol / L), sonicated (25 kHz, 15 min), and then heat-treated at 250 °C for 1.5 h (stirring 150 rpm). SEM showed that the gold nanoparticles had a particle size of 25-50 nm.

[0065] Post-processing

[0066] The washing, drying, and sieving conditions were the same as in Example 1 to obtain the fluorescent powder.

[0067] Performance Testing and Application

[0068] Fluorescence testing shows that the luminescence intensity under ultraviolet light (365nm) excitation is 35% higher than that of ordinary phosphors. When used in white LED lighting devices, the color rendering index is improved by 15% and the luminous efficacy is increased by 25%. In fluorescent anti-counterfeiting labels, it can produce a unique blue-to-yellow multicolor fluorescence change, enhancing anti-counterfeiting performance.

[0069] Example 3

[0070] Surface plasmon-enhanced Mn 4+ Preparation of doped double perovskite phosphors

[0071] Raw material preparation and pretreatment

[0072] Potassium carbonate (K₂CO₃) was selected as the A source compound, sodium nitrate (NaNO₃) as the B' source compound, and niobium pentachloride (NbCl₅) as the B” source compound. The raw materials were ground to 15-35 μm and dried at 65 °C and 0.07 MPa vacuum for 3.5 hours.

[0073] Synthesis of double perovskite matrix

[0074] Weigh the material according to the K2NaNbO6 metering ratio, place it in a stainless steel ball mill jar, ball ratio 9:1, ball mill for 4 hours at 400 rpm, sinter at 1000℃ for 12 hours (air atmosphere, heating rate 7℃ / min), after cooling the particle size is 30-60μm, and XRD test is qualified (scan step 0.035°, speed 4° / min).

[0075] Mn 4+ Doping preparation

[0076] Potassium permanganate (KMnO4) is used as the Mn-containing base. 4+ The compound was ball-milled with the matrix at a doping concentration of 1 mol% for 5 hours at a speed of 500 rpm and a ball-to-material ratio of 7:1.

[0077] Mn 4+ Doping sintering

[0078] Secondary sintering at 900℃ for 8 hours (heating rate 6℃ / min), after cooling, the particle size was 40-70μm. Mn was determined by ICP-AES. 4+ Concentration 0.98 mol%.

[0079] Introduction of metal nanoparticles

[0080] Aluminum nanoparticles were synthesized in situ. The mixture was prepared by mixing with aluminum nitrate solution (concentration 0.1 mol / L), followed by ultrasonication (35 kHz, 25 min) and heat treatment at 180 °C for 3 h (stirring 250 rpm). SEM showed that the aluminum nanoparticles had a particle size of 40-70 nm.

[0081] Post-processing

[0082] The phosphor was obtained by washing, drying, and sieving according to Example 1.

[0083] Performance Testing and Application

[0084] The luminous intensity is increased by 30% under blue light (460nm) excitation. When applied to LCD backlights, color saturation is increased by 20% and luminous efficiency is increased by 28%. In terms of fluorescent anti-counterfeiting, it can achieve multi-color fluorescent anti-counterfeiting from green to orange, with high reliability.

[0085] Comparative Example

[0086] Preparation and processing of traditional double perovskite phosphors

[0087] Raw materials and preparation

[0088] Using the same raw materials as in Example 1 (Cs2AgSbO6 matrix), but without the addition of metal nanoparticles, only the double perovskite matrix synthesis and Mn were performed. 4+ The doping steps and parameters during the preparation process are the same as in Example 1 (except for the steps related to metal nanoparticles).

[0089] Performance testing

[0090] Performance tests were conducted on this phosphor. Under blue light (450nm) excitation, its luminescence intensity was significantly lower than that of the phosphor prepared in Example 1. When applied to the backlight of an organic light-emitting diode display, the improvement in color saturation and luminous efficiency was far less than that of Example 1. In fluorescent anti-counterfeiting label applications, it can only emit fluorescence of a single color, resulting in poor anti-counterfeiting effectiveness.

[0091] Surface plasmon-enhanced Mn prepared in Examples 1-3 4+The doped double perovskite phosphor outperforms the comparative traditional phosphor in several aspects. Regarding luminescence performance, the luminescence intensity of the embodiment is increased by 30%-40% due to the introduction of metal nanoparticles, while the comparative does not show this enhancement. In display applications, the embodiment shows significant improvements in color saturation and luminous efficiency when applied to different displays; for example, Embodiment 1 shows a 25% increase in color saturation and a 30% increase in luminous efficiency on an OLED display, while the comparative shows limited improvement. In the field of anti-counterfeiting applications, the embodiment can achieve multi-color fluorescent anti-counterfeiting, while the comparative can only emit a single color, resulting in weak anti-counterfeiting capabilities.

[0092] In summary, the phosphor of this invention effectively improves fluorescence performance through surface plasmon enhancement technology, exhibiting excellent characteristics in applications such as display and anti-counterfeiting, and has broad application prospects and significant advantages.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A surface plasmon-enhanced Mn 4+ A method for preparing doped double perovskite phosphors, characterized in that, Includes the following steps: S1: Raw material pretreatment: Alkali metal or alkaline earth metal carbonates or nitrates are selected as source compounds A, monovalent metal halides or nitrates are selected as source compounds B', and pentavalent metal oxides or halides are selected as source compounds B”. The raw materials are ground, and the particle size of the ground raw materials is controlled at 10-50μm. Then, they are placed in a vacuum drying oven and dried at 60-80℃ for 2-4 hours to remove moisture and impurities. S2: Synthesis of the double perovskite matrix. The treated A-source, B'-source, and B”-source compounds were accurately weighed according to the stoichiometric ratio of the double perovskite structure A2B'B”O6 and placed in a ball mill jar. Zirconia balls were added as the grinding medium, with a ball-to-material ratio of 5:1-10:

1. The mixture was ball-milled using a planetary ball mill for 3-8 hours at a speed of 300-800 rpm to obtain a uniformly mixed raw material powder. The powder was then transferred to an alumina crucible and sintered in a high-temperature furnace at 900-1300℃ for 6-15 hours in an air or oxygen atmosphere with a heating rate controlled at 5-10℃ / min to synthesize the double perovskite matrix material. After the synthesized matrix material was naturally cooled to room temperature, it was ground again to a particle size of 20-100μm. S3: Mn 4+ For doping preparation, permanganate or manganese oxide is selected as the Mn-containing substrate. 4+ The compound was combined with the synthesized double perovskite matrix material according to Mn 4+ The target doping concentration was measured and then placed in a ball mill jar. Zirconia balls were added at a ball-to-material ratio of 4:1-8:

1. The mixture was then ball-milled using a planetary ball mill for 2-6 hours at a speed of 200-600 rpm. 4+ The compound is uniformly dispersed in the double perovskite matrix material; S4:Mn 4+ After doping and sintering, the ball-milled mixture is transferred to an alumina crucible and placed in a high-temperature furnace for secondary sintering at 800-1100℃ for 3-10 hours, with a heating rate controlled at 3-8℃ / min, to induce Mn doping and sintering. 4+ Doping into the double perovskite matrix lattice yields Mn 4+ The doped perovskite material is sintered, then naturally cooled to room temperature, and then ground to a particle size of 30-120 μm. S5: Introduction of metal nanoparticles, using in-situ synthesis in Mn 4+ Metal nanoparticles are introduced onto the surface of doped double perovskite materials. A metal salt solution is then mixed with Mn... 4+ The doped double perovskite material is uniformly mixed with a metal salt solution at a concentration of 0.05-0.5 mol / L. Ultrasonic dispersion is used during mixing at a frequency of 20-40 kHz for 10-30 minutes. The mixture is then heat-treated at 150-300℃ for 1-4 hours with continuous stirring at a speed of 100-300 rpm. This process forms metal nanoparticles with a diameter of 20-80 nm on the material surface, resulting in surface plasmon-enhanced MnO2. 4+ Doped double perovskite phosphor.

2. The preparation method according to claim 1, characterized in that: In step S1, the vacuum level of the vacuum drying oven is maintained at 0.05-0.1 MPa; In step S2, the grinding jar of the planetary ball mill is made of stainless steel or hard alloy, and the grinding process is paused for 5-10 minutes every 1-2 hours to prevent the material from overheating. In step S3, the milling jar must be cleaned with anhydrous ethanol and dried before use to avoid contamination by impurities. In step S4, the furnace lining of the high-temperature furnace is made of high-purity alumina or mullite, which has good high-temperature resistance and heat insulation properties. In step S5, the metal salt solution is prepared using deionized water or anhydrous ethanol as the solvent and must be filtered through a 0.2-0.5 μm filter membrane to remove impurities.

3. The preparation method according to claim 1, characterized in that: In step S2, the heating element of the high-temperature furnace is a silicon molybdenum rod or a graphite rod, which enables precise temperature control. In step S3, the planetary ball mill is cooled by water or air to ensure stable equipment temperature during the ball milling process. In step S4, the cooling process after secondary sintering can be carried out by furnace cooling or cooling under inert gas protection to reduce material oxidation or other impurity contamination. In step S5, the heat treatment equipment is a constant temperature oven or tube furnace with stirring and temperature control functions, which can precisely control the reaction conditions.

4. The preparation method according to claim 1, characterized in that: In step S2, the crystal structure of the synthesized double perovskite matrix material was detected by X-ray diffraction (XRD) to ensure that it conforms to the characteristics of double perovskite structure. The scanning step size of XRD detection was 0.02-0.05° and the scanning speed was 1-5° / min. In step S4, Mn 4+ Mn doped double perovskite materials 4+ The doping concentration was accurately determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), with the measurement error controlled within ±0.05 mol%. In step S5, the particle size and distribution of the metal nanoparticles are observed and analyzed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The resolution of SEM is 1-5 nm, and the resolution of TEM is 0.1-1 nm.

5. The preparation method according to claim 1, characterized in that: Following step S5, the obtained phosphor undergoes post-treatment. It is first washed alternately with deionized water and anhydrous ethanol 3-5 times, followed by centrifugation at 3000-6000 rpm for 5-15 minutes after each wash. The washed phosphor is then vacuum-dried at 50-70℃ for 2-4 hours at a vacuum degree of 0.08-0.12 MPa. Finally, it is passed through a 200-500 mesh sieve to obtain uniform and pure surface plasmon-enhanced Mn. 4+ Doped double perovskite phosphor.

6. The preparation method according to claim 1, characterized in that: Throughout the entire preparation process, all operations are carried out in a dust-free environment with a constant temperature of 20-25℃ and a constant humidity of 40%-60%, minimizing the impact of external factors on the material quality.

7. The preparation method according to claim 1, characterized in that: During the high-temperature sintering process in steps S2 and S4, an intelligent temperature control system is used to automatically adjust the heating power according to the preset temperature curve, with a temperature control accuracy of ±1℃.

8. A surface plasmon-enhanced Mn 4+ The application of doped double perovskite phosphors is characterized by: The fluorescent powder is applied to the preparation of fluorescent anti-counterfeiting labels. By adjusting the doping concentration of the fluorescent powder and the content of metal nanoparticles, the fluorescence emission wavelength and intensity of the fluorescent anti-counterfeiting label under specific excitation light are controlled to achieve a multi-color fluorescent anti-counterfeiting effect. The mass fraction of the fluorescent powder in the anti-counterfeiting label material is 5-30%. The fluorescent powder is mixed evenly with organic resins, including epoxy resin and polyurethane resin, and then coated, printed, or injection molded to prepare fluorescent anti-counterfeiting labels. In the printing process, flexographic or screen printing plates are used, the printing pressure is 0.1-0.5 MPa, and the printing speed is 1-5 m / s. In the injection molding process, the injection temperature is 150-250℃, the injection pressure is 50-150 MPa, and the mold temperature is 30-80℃.

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