Er < 3 + > and Pr < 3 + > co-doped calcium tungstate-based multi-mode luminescent fluorescent material as well as preparation method and application thereof

Abstract

The invention discloses an Er < 3 + > and Pr < 3 + > co-doped calcium tungstate-based multi-mode luminescent fluorescent material as well as a preparation method and application thereof, and relates to the technical field of preparation of inorganic rare earth luminescent materials. The invention relates to an Er < 3 + > and Pr < 3 + > co-doped calcium tungstate-based multi-mode luminescent fluorescent material, the chemical structural formula is Ca < 1-x-y > Er < x > Pr < y > WO < 4 >, x < lt >; 0.025, 0 lt; y < lt >; and 0.025% by weight. In the fluorescent material, Er < 3 + > and Pr < 3 + > are co-doped in calcium tungstate crystal lattices. According to the fluorescent material, down-conversion luminescence and up-conversion luminescence are integrated in a single stable system, the multi-mode luminescence performance is achieved, luminescence with different characteristics can be obtained in different excitation modes, and dynamic change of the luminescence characteristics can be achieved. Moreover, the multi-mode luminescent fluorescent material disclosed by the invention is high in luminous efficiency, low in toxicity, free of pollution and stable in chemical and physical properties.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic rare earth luminescent material preparation, specifically comprising an Er 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material, preparation method, and application thereof. Background Art

[0002] With the continuous advancement of science and technology and society, the economy, life, property, and the nation are placing higher demands on security and anti-counterfeiting. Therefore, the development and use of anti-counterfeiting systems with encryption and decryption technologies are of great significance for safeguarding the personal information security of governments and everyday life. Currently, various technologies and materials, including trademarks, magnetic inks, laser holograms, plasma labels, and luminescent materials, are widely used in the field of information security. Among them, luminescent materials are widely considered to be the most ideal materials for information encryption and anti-counterfeiting due to their advantages such as good visibility, simple design, and convenient operation. Generally, information stored in luminescent materials requires external light to be effectively read, which improves the security of data storage to a certain extent. However, this single pattern is predictable, making the stored information easily copied or overwritten. Therefore, to more securely store and protect information, it is necessary to combine multiple security elements to achieve multi-level information encryption.

[0003] Rare earth-doped inorganic luminescent materials, as advanced phosphors, have attracted widespread attention due to their excellent luminescence properties. The significant advantages of rare earth ions and inorganic host materials offer tremendous potential for generating multidimensional luminescence. Rare earth ions possess a rich spectrum of energy levels, with absorption and emission energy levels covering the ultraviolet, visible, and near-infrared regions. Combining rare earth ions of different luminescent colors can produce desired multicolor emission. Furthermore, inorganic host materials generally possess stable physicochemical properties, low toxicity, and good environmental tolerance, making them highly valuable for applications in daily life.

[0004] A Chinese patent discloses a calcium tungstate phosphor, wherein the trivalent praseodymium ion Pr 3+ The doping amount is 0.5 mol%, trivalent samarium ion Sm 3+ The doping level is 1-2 mol%. This calcium tungstate phosphor produces orange-yellow light when excited by near-ultraviolet or blue light. Although doped with two rare earth ions, this calcium tungstate phosphor only emits a single color of light. This fluorescent anti-counterfeiting material has a limited security feature, static luminescence characteristics, and is easily forged, failing to meet anti-counterfeiting requirements. Summary of the Invention

[0005] The present application aims to overcome the defects and shortcomings that the existing rare earth doped calcium tungstate fluorescent powder can only realize monochromatic emission under single wavelength excitation and cannot obtain light emission with different characteristics under different excitation modes, and provides an Er 3+ , Pr 3 + Co-doped calcium tungstate-based multimodal luminescent fluorescent material, which can emit blue fluorescence under light excitation of at least 252-256 nm, and can emit red fluorescence under light excitation of 448-452 nm and green fluorescence under light excitation of 980 nm.

[0006] Another object of the present application is to provide a preparation method of the Er 3+ , Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material.

[0007] Still another object of the present application is to provide an application of the Er 3+ , Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material.

[0008] To achieve the above object, the present application is realized by the following steps: An Er 3+ , Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material, the chemical structural formula of which is Ca 1-x- y Er x Pr y WO4, wherein 0 < x < 0.025, 0 < y < 0.025.

[0009] In the fluorescent material of the present application, Er 3+ , Pr 3+ is co-doped in the calcium tungstate crystal lattice. The fluorescent material of the present application integrates down-conversion luminescence and up-conversion luminescence in a single stable system, has multimodal luminescence performance, that is, light emission with different characteristics can be obtained under different excitation modes, and dynamic changes of luminescence characteristics can be realized. Moreover, the multimodal luminescent fluorescent material of the present application has low toxicity, no pollution, and stable chemical and physical properties at high temperature.

[0010] In practical application, 0.001≤x≤0.024. x can be 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021, 0.022, 0.023, 0.024.

[0011] In practical applications, 0.001≤y≤0.024. y can be 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021, 0.022, 0.023, 0.024.

[0012] Preferably, when 0.005≤x≤0.015, 0.010≤y≤0.020, x+y=0.025, the fluorescent material emits blue fluorescence under excitation of light with a wavelength of 252-256 nm; emits red fluorescence under excitation of light with a wavelength of 376-380 nm; emits red fluorescence under excitation of light with a wavelength of 448-452 nm; and emits green fluorescence under excitation of light with a wavelength of 980 nm.

[0013] Preferably, when 0.018≤x≤0.022, 0.003≤y≤0.007, x+y=0.025, the fluorescent material emits blue fluorescence under excitation of light with a wavelength of 252-256 nm; emits green fluorescence under excitation of light with a wavelength of 376-380 nm; emits red fluorescence under excitation of light with a wavelength of 448-452 nm; and emits green fluorescence under excitation of light with a wavelength of 980 nm.

[0014] The multi-modal luminescent fluorescent material of the present application can adjust the doping ratio of Er 3+ , Pr 3+ , realize the proportion control of blue, green and red three kinds of luminescent colors, and can be used for customized fluorescent anti-counterfeiting.

[0015] The present application also protects the preparation method of the Er 3+ , Pr 3+ -codoped calcium tungstate-based multi-modal luminescent fluorescent material described in any of the above, comprising the following steps: S1: taking calcium compounds, tungsten compounds, erbium compounds and praseodymium compounds according to the chemical formula stoichiometric ratio, mixing and grinding uniformly; S2: placing the mixed powder of S1 in an air atmosphere or an oxygen atmosphere and calcining, the calcining temperature is 800-1200 ℃, and the calcining time is 4-10 h, thereby obtaining the Er 3+ , Pr 3+ -codoped calcium tungstate-based multi-modal luminescent fluorescent material.

[0016] The Er 3+ , Pr 3+The co-doped calcium tungstate-based multi-modal luminescent fluorescent material can be synthesized by a high-temperature solid-phase method.

[0017] Preferably, the calcium compound is one or more of calcium oxide, calcium carbonate, calcium nitrate, calcium oxalate, and calcium acetate; the tungsten compound is tungsten oxide; the erbium compound is one or more of erbium oxide and erbium carbonate; and the praseodymium compound is one or more of praseodymium oxide and praseodymium carbonate.

[0018] The present application also protects the Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material described in any of the above. 3+ 3+ The co-doped calcium tungstate-based multi-modal luminescent fluorescent material is used in the preparation of information encryption or anti-counterfeiting materials.

[0019] The multi-modal luminescent fluorescent material described in the present application can be effectively excited by 252-256 nm, 376-380 nm, 448-452 nm, and 980 nm light, respectively emitting blue, green, or red, red, and green visible light, realizing multi-modal luminescence and meeting the performance requirements of fluorescent powder in the field of information encryption and anti-counterfeiting. Therefore, the application of the multi-modal luminescent fluorescent material in the field of information encryption and anti-counterfeiting should also be within the scope of protection of the present application.

[0020] Multi-modal luminescence can produce light with different characteristics under different excitation modes, and can realize dynamic changes in luminescent characteristics, thereby significantly improving the technical security and security level of anti-counterfeiting.

[0021] In practical applications, the multi-modal luminescent fluorescent material of the present application is excited by photoluminescence, which is simpler and milder than thermoluminescence and mechanoluminescence, and has less damage to the substrate.

[0022] Moreover, the multi-modal luminescent fluorescent material of the present application is all down-conversion luminescence, which does not require the use of high-power lasers and can be achieved using small-power light-emitting diodes, and the excitation light source is easy to integrate.

[0023] Preferably, in practical applications, the Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material can be excited by 252-256 nm light, and the fluorescent material exhibits blue fluorescence.

[0024] Preferably, in practical applications, the Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material can be excited by 376-380 nm light, and the fluorescent material exhibits green fluorescence or red fluorescence.

[0025] Preferably, in practical applications, the Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material shows red fluorescence.

[0026] Preferably, in practical applications, the Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material shows green fluorescence.

[0027] Compared with the prior art, the present application has the following beneficial effects: The present application discloses an Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material, which has a chemical structural formula of Ca 1-x-y Er x Pr y WO4, wherein 0 < x < 0.025 and 0 < y < 0.025.

[0028] In the fluorescent material of the present application, the Er 3+ , Pr 3+ co-doping is in the calcium tungstate crystal lattice. The fluorescent material of the present application integrates down-conversion luminescence and up-conversion luminescence in a single stable system, has multi-modal luminescence performance, i.e. can obtain luminescence with different characteristics under different excitation modes, and can realize dynamic changes of luminescence characteristics. Moreover, the multi-modal luminescent fluorescent material of the present application has low toxicity, no pollution, and stable chemical and physical properties. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The XRD pattern of the multi-modal luminescent fluorescent material described in Example 1 of the present application; Figure 2 The emission spectrum of the multi-modal luminescent fluorescent material described in Example 1 of the present application under excitation of 254 nm light.

[0030] Figure 3 The emission spectrum of the multi-modal luminescent fluorescent material described in Example 1 of the present application under excitation of 378 nm light.

[0031] Figure 4 The emission spectrum of the multi-modal luminescent fluorescent material described in Example 1 of the present application under excitation of 450 nm light.

[0032] Figure 5 The emission spectrum of the multi-modal luminescent fluorescent material described in Example 1 of the present application under excitation of 980 nm light.

[0033] Figure 6 CIE color coordinate diagram of the multi-modal luminescent phosphor according to the present application embodiment 1-4.

[0034] Figure 7 B / G / R pie chart of the multi-modal luminescent phosphor according to the present application embodiment 1 under the excitation of 254 nm, 378 nm, 450 nm, 980 nm wavelength light. DETAILED DESCRIPTION

[0035] The present application will be further described in conjunction with the accompanying drawings and specific embodiments, but the embodiments do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0036] Unless otherwise specified, the reagents and materials used in the following embodiments are commercially available.

[0037] The chemical reagents used in the examples of the present application are all analytical grade products.

[0038] Example 1 (Ca 0.975 Er 0.020 Pr 0.005 WO4) An Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent phosphor has a chemical structural formula of Ca 0.975 Er 0.020 Pr 0.005 WO4. The preparation method of the above-mentioned phosphor comprises the following steps: taking CaCO3, WO3, Er2O3, Pr2O3 as raw materials, and taking 1.5 mmol of raw materials according to the stoichiometric ratio of each element in the chemical formula Ca 0.975 Er 0.020 Pr 0.005 WO4, wherein the mass of CaCO3 is 0.1464 g, the mass of WO3 is 0.3479 g, the mass of Er2O3 is 0.0057 g, and the mass of Pr2O3 is 0.0013 g. The weighed raw materials are ground and mixed uniformly in an agate mortar, and the obtained mixed powder is loaded into a corundum crucible, and then the corundum crucible is placed in a muffle furnace and heated at a rate of 5 ℃ / min to 1000 ℃, and then kept for 6 h in an air atmosphere. After natural cooling to room temperature, the obtained sample is ground again in an agate mortar to obtain the product Ca 0.975 Er 0.020 Pr 0.005 WO4 multi-modal luminescent phosphor.

[0039] Example 2 (Ca 0.975 Er 0.015Pr 0.010 WO4 An Er 3+ , Pr 3+ co-doped calcium tungstate-based multimodal luminescent fluorescent material, having a chemical structural formula of Ca 0.975 Er 0.015 Pr 0.010 WO4.

[0040] The preparation method of the above fluorescent material comprises the following steps: taking CaCO3, WO3, Er2O3 and Pr2O3 as raw materials, and according to the stoichiometric ratio of each element in the chemical formula Ca 0.975 Er 0.015 Pr 0.010 WO4, 1 mmol of the raw materials are weighed, wherein the mass of CaCO3 is 0.0976 g, the mass of WO3 is 0.2319 g, the mass of Er2O3 is 0.0029 g, and the mass of Pr2O3 is 0.0017 g. The weighed raw materials are ground and mixed uniformly in an agate mortar, the obtained mixed powder is loaded into a corundum crucible, and then the corundum crucible is placed in a muffle furnace and heated at a rate of 5 ℃ / min to 1000 ℃, and then the temperature is kept for 6 h in an air atmosphere. After natural cooling to room temperature, the obtained sample is ground again in an agate mortar, and the product Ca 0.975 Er 0.015 Pr 0.010 WO4 multimodal luminescent fluorescent material is obtained.

[0041] Example 3 (Ca 0.975 Er 0.010 Pr 0.015 WO4 An Er 3+ , Pr 3+ co-doped calcium tungstate-based multimodal luminescent fluorescent material, having a chemical structural formula of Ca 0.975 Er 0.010 Pr 0.015 WO4.

[0042] The preparation method of the above fluorescent material comprises the following steps: taking CaCO3, WO3, Er2O3 and Pr2O3 as raw materials, and according to the stoichiometric ratio of each element in the chemical formula Ca 0.975 Er 0.015 Pr 0.010The stoichiometric ratio of each element in WO4 is taken as 1 mmol of raw materials, wherein the mass of CaCO3 is 0.0976 g, the mass of WO3 is 0.2319 g, the mass of Er2O3 is 0.0019 g, and the mass of Pr2O3 is 0.0026 g. The weighed raw materials are placed in an agate mortar and ground to be uniformly mixed, the obtained mixed powder is loaded into a corundum crucible, and then the corundum crucible is placed in a muffle furnace and heated at a rate of 5 ℃ / min to 1000 ℃, and then the temperature is kept for 6 h in an air atmosphere. After natural cooling to room temperature, the obtained sample is placed in an agate mortar and ground again to obtain the product Ca 0.975 Er 0.010 Pr 0.015 WO4 multi-modal luminescent fluorescent material.

[0043] Example 4 (Ca 0.975 Er 0.005 Pr 0.020 WO4) An Er 3+ , Pr 3+ co-doped calcium tungstate-based multi-modal luminescent fluorescent material, the chemical structural formula of which is Ca 0.975 Er 0.005 Pr 0.020 WO4.

[0044] The preparation method of the above fluorescent material comprises the following steps: taking CaCO3, WO3, Er2O3 and Pr2O3 as raw materials, and taking the stoichiometric ratio of each element in Ca 0.975 Er 0.005 Pr 0.020 WO4 as 1 mmol of raw materials, wherein the mass of CaCO3 is 0.0976 g, the mass of WO3 is 0.2319 g, the mass of Er2O3 is 0.0010 g, and the mass of Pr2O3 is 0.0034 g. The weighed raw materials are placed in an agate mortar and ground to be uniformly mixed, the obtained mixed powder is loaded into a corundum crucible, and then the corundum crucible is placed in a muffle furnace and heated at a rate of 5 ℃ / min to 1000 ℃, and then the temperature is kept for 6 h in an air atmosphere. After natural cooling to room temperature, the obtained sample is placed in an agate mortar and ground again to obtain the product Ca 0.975 Er 0.005 Pr 0.020 WO4 multi-modal luminescent fluorescent material.

[0045] Performance test 1. Test method (1) X-ray powder test method (instrument used and test conditions): X-ray powder diffraction uses D-MAX2200VPC instrument, fixed Cu target, test voltage 40 KV, current 26 MA. (2) Test method of emission spectrum (used instrument and test condition): Excitation and emission spectrum were tested by Edinburgh FLS 980, and the light source was xenon lamp. (3) Test method of luminescence intensity (used instrument and test condition): FLS 980 spectrum test was used to directly read the luminescence intensity at different wavelengths. (4) The color coordinates of the product emission light obtained in Example 1 were calculated by using the color purity calculation software CIE1931 with version number V.1.6.0.2.

[0046] 2. Test results (1) XRD test: The XRD spectrum of the material prepared in Example 1 is shown in Figure 1 , and the XRD spectra of Examples 2-4 are basically the same as that of Example 1. It can be seen from Figure 1 that the material prepared by the preparation method forms a good single phase, and no impurity phase appears, and has good crystallinity. The introduction of Pr 3+ , Er 3+ ion XRD diffraction peak position of phosphor is basically the same as that of CaWO4 (standard card ICSD-33179) of tetragonal scheelite. There is no Pr2(WO4)3 (standard card ICSD-47021), Er2WO6 (standard card ICSD-20938) impurity phase peak. This shows that the synthesized sample is a pure phase of CaWO4, that is, a small amount of Er 3+ , Pr 3+ ion can be successfully doped into the CaWO4 crystal lattice, and does not change its crystal structure.

[0047] (2) The spectrum of the multi-modal luminescent phosphor prepared in Example 1 under 254 nm, 378 nm and 450 nm light excitation is shown in Figures 2-4 .From Figure 2 , it can be seen that under 254 nm light excitation, the multi-modal luminescent phosphor prepared in Example 1 can observe the broadband emission of the substrate in the range of 320-520 nm and the narrowband emission of Er 3+ ion in the range of 540-560 nm and Pr 3+ ion in the range of 640-660 nm. As shown in Figure 3 , under 378 nm light excitation, the luminescence color of the multi-modal luminescent phosphor prepared in Example 1 is green, and the strongest emission peak wavelength is 553 nm. As shown in Figure 4 , under 450 nm light excitation, the luminescence color of the multi-modal luminescent phosphor prepared in Example 1 is red, and the strongest emission peak wavelength is 649 nm. As shown in Figure 5As shown, under 980 nm light excitation, the luminescent color of the multi-modal luminescent fluorescent material prepared in Example 1 is green light, and two emission peaks can be observed, and the strongest emission wavelengths are 530 nm and 551 nm, respectively. It can be seen that the fluorescent material of the present application integrates down-conversion luminescence and up-conversion luminescence in a single stable system.

[0048] (3) The CIE chromaticity diagram of the material prepared in Examples 1-4 is shown in Figure 6 . As shown in the attached Figure 6 , it can be seen that the CIE chromaticity diagram of the Ca 0.975 Er 0.020 Pr 0.005 WO4 multi-modal luminescent fluorescent material prepared in Example 1 is green light, and two emission peaks can be observed, and the strongest emission wavelengths are 530 nm and 551 nm, respectively.

[0049] (4) The B / G / R pie chart of the multi-modal luminescent fluorescent material prepared in Example 1 under 254 nm, 378 nm, 450 nm, and 980 nm wavelength light excitation of blue, green, and red light is shown in Figure 7 . In addition, the B / G / R ratio of the multi-modal luminescent fluorescent material prepared in Examples 1-4 under 254 nm, 378 nm, 450 nm, and 980 nm wavelength light excitation of blue, green, and red light is shown in Table 1.

[0050] Table 1: B / G / R ratio of the emission light of Examples 1-4 under different wavelength light excitation

[0051] From Figure 7 and Table 1, it can be seen that in Examples 1-4, the color purity of the material of Example 1 is higher, and the multi-modal luminescent performance is the best.

[0052] The multi-modal luminescent fluorescent material prepared in Examples 2-4 emits blue light under 254 nm light excitation, emits red light under 378 nm light excitation, emits red light under 450 nm light excitation, and emits green light under 980 nm light excitation, and has multi-modal luminescent performance.

[0053] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A kind of Er 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material, characterized in that: The chemical formula is Ca 1-x-y Er x Pr y WO4, where 0 < x < 0.025, 0 < y < 0.

025.

2. According to claim 1, Er 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material, characterized in that: 0.005 ≤ x ≤ 0.015, 0.010 ≤ y ≤ 0.020, x + y=0.

025.

3. According to claim 1 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent material, characterized in that: 0.018 ≤ x ≤ 0.022, 0.003 ≤ y ≤ 0.007, x + y=0.

025.

4. Er according to any one of claims 1 to 3 3+ 、Pr 3+ The preparation method of co-doped calcium tungstate-based multimodal luminescent fluorescent material is characterized in that: The method comprises the following steps: S1: weighing a calcium compound, a tungsten compound, an erbium compound, and a praseodymium compound according to a stoichiometric ratio, mixing and grinding the mixture; S2: calcining the mixed powder of S1 in an air atmosphere or an oxygen atmosphere at a calcination temperature of 800-1200°C and a calcination time of 4-10 hours to obtain the Er 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent materials.

5. According to claim 4 3+ 、Pr 3+ The preparation method of co-doped calcium tungstate-based multimodal luminescent fluorescent material is characterized in that: The calcium compound is one or more of calcium oxide, calcium carbonate, calcium nitrate, calcium oxalate, and calcium acetate; the tungsten compound is tungsten oxide; the erbium compound is one or more of erbium oxide and erbium carbonate; and the praseodymium compound is one or more of praseodymium oxide and praseodymium carbonate.

6. Er according to any one of claims 1 to 3 3+ 、Pr 3+ Application of co-doped calcium tungstate-based multimodal luminescent fluorescent materials in the preparation of information encryption or anti-counterfeiting materials.

7. The application according to claim 6, characterized in that The Er was excited by 252~256 nm light 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent materials.

8. The use according to claim 6, characterized in that The Er was excited by 376-380 nm light. 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent materials.

9. The use according to claim 6, characterized in that: The Er was excited by 448-452 nm light. 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent materials.

10. The use according to claim 6, characterized in that: The Er was excited by 980 nm light 3+ 、Pr 3+ Co-doped calcium tungstate-based multimodal luminescent fluorescent materials.

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