A multi-mode intelligent response luminescent material and a preparation method and application thereof

Abstract

The application provides a multi-mode intelligent response luminescent material and a preparation method and application thereof. The chemical expression of the luminescent material is CaWO4:x%Yb 3+ ,Er 3+ ,Eu 3+ ;0

Description

Technical Field

[0001] This invention relates to the field of multicolor material luminescence technology, specifically to a multimode intelligent response luminescent material, its preparation method, and its application. Background Technology

[0002] Currently, information security is an increasingly important global issue, and luminescent materials have been widely used in the field of anti-counterfeiting. Due to their excellent visibility, ease of design, and the widespread availability of portable lighting fixtures as irradiation sources, luminescent materials are generally considered one of the most ideal anti-counterfeiting technologies. However, the luminescent color of most current anti-counterfeiting marks does not change under fixed stimuli, making them easily counterfeited by other substitutes.

[0003] With the urgent need for luminescent materials, numerous materials have been designed and developed in existing technologies to achieve high-quality performance. These include carbon dots, semiconductor quantum dots, perovskites, organic dyes, and luminescent materials. 3+ Doped nanoparticles are excellent luminescent materials. More importantly, their luminescence can be excited, quenched, or tuned by external stimuli such as light, heat, chemical reagents, and mechanical forces. Although many multi-mode, multi-color luminescence anti-counterfeiting strategies have been developed in recent years for complex anti-counterfeiting applications, the colors are not rich enough to produce multiple colors. Moreover, existing technologies usually use different doping ions to achieve multiple color and multi-mode changes, but it is difficult to achieve multiple ions doping in the general parent material during the preparation process. Only materials with special structures that can simultaneously achieve multiple colors and modes and successfully dope multiple luminescent central ions can achieve the co-luminescence of multiple ions. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-mode intelligent responsive luminescent material, the chemical formula of which is: CaWO4:x%Yb 3+ Er 3+ Eu 3+ ; among which, 0 <x≤2。

[0005] Another object of the present invention is to provide a method for preparing a multimode intelligent responsive luminescent material, comprising:

[0006] Step (1): Mix CaO or CaCO3, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol in a ratio of 1:1:x%:x%:x%, grind them evenly, and press the evenly mixed powder into tablets to obtain tablet-shaped reactants.

[0007] Step (2): The reactants are sintered at high temperature in air atmosphere at a temperature of 1000-1100℃, a heating rate of 4-6℃ / min, and a holding time of 5-7h. The mixture is then air-cooled to room temperature to obtain the multimode intelligent responsive luminescent material.

[0008] As a further preferred option of the above scheme:

[0009] The grinding method is ball milling, with a ball-to-material ratio of 1:5-30, anhydrous ethanol covering the balls, a ball milling speed of 700-900 r / min, and a ball milling time of more than 6 hours.

[0010] As a further preferred option of the above scheme:

[0011] In step (1), CaO, WO3, Yb2O3, Er2O3 and Eu2O3 are mixed in a ratio of 1:1:0.01:0.01:0.01.

[0012] As a further preferred option of the above scheme:

[0013] The method for compressing the reactants in step (1) is as follows: press the reactants at 120-150 MPa for 1-5 minutes to obtain round, sheet-like reactants.

[0014] Another objective of this invention is to provide an application of the aforementioned multimode intelligent responsive luminescent material, applying the multimode intelligent responsive luminescent material to a screen printing anti-counterfeiting environment.

[0015] As a further preferred option of the above scheme:

[0016] The multimode intelligent responsive luminescent material exhibits changes in fluorescence—red, pink, and yellow—under 254nm ultraviolet light irradiation.

[0017] As a further preferred option of the above scheme:

[0018] The multi-mode intelligent response luminescent material changes from bright yellow to green under 365nm ultraviolet light irradiation.

[0019] The beneficial effects of this invention are as follows: A luminescent material is obtained by using CaWO4 as the parent material and doping it with three ions (Yb3+, Er3+, Eu3+). This luminescent material exhibits energy storage properties, wavelength dependence, and temperature responsiveness, achieving a multi-mode response effect, as detailed below:

[0020] 1. The parent material used in this invention is CaWO4, which solves the problem that it is difficult to achieve multiple ion doping in the parent material in the prior art. CaWO4 with scheelite structure is the main light emitter. The advantages of choosing this material as the parent material in this invention are: (1) The inherent blue-green emission wavelength of CaWO4 material at room temperature is between 240-537nm; (2) The emission of other different colors of light: different types of rare earth ions (Ln 3+(3) Incorporating it into the CaWO4 framework may change the possibility of light emission, realize multiple ion doping, and the emission lines can influence each other and contribute to light emission, thus realizing multi-mode and multi-color light emission; (4) CaWO4 material has stable physicochemical properties, high luminous efficiency and economic value;

[0021] 2. The luminescent material of this invention can be well applied in screen printing anti-counterfeiting environments. The luminescent material uses CaWO4 as the matrix and Er... 3+ Eu 3+ As the luminescent center, the material exhibits red, pink, and yellow fluorescence under 254nm UV light irradiation in environments ranging from low to high temperatures. Under 365nm UV light irradiation, it changes from bright yellow to green, while under 980nm UV light irradiation, the color shows no significant change, remaining green due to the upconversion pair. The prepared material, after pre-excitation with a 254nm UV light for 1 minute, instantaneously releases energy and emits red fluorescence at 300°C. This invention introduces Yb... 3+ Er 3+ Upconversion pairs increase the variety of colors in luminescent materials; after excitation with different wavelengths, upconversion luminescence and Er luminescence occur. 3+ Light emission; and the introduction of Eu 3+ Subsequently, the increase of new ions increases the types of defects in the luminescent material, enhances its energy storage properties, and enables new colors. These new ions can also interact with the self-luminescence of the parent material, and the three factors further influence the color change, thus obtaining multi-color indication in multiple modes.

[0022] 3. The raw materials used in this invention are widely available and low in cost. The preparation process is simple, requiring only mixing, grinding and sintering. The operating environment is simple, requiring no reducing atmosphere protection. The proportions are accurate and highly repeatable, making it suitable for large-scale production. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 The X-ray diffraction pattern of the material prepared in Example 3 of this invention;

[0025] Figure 2 The emission and excitation spectra of the material prepared in Example 3 of this invention;

[0026] Figure 3 Sunlight photographs and emission photographs at different excitation wavelengths of the material prepared in Example 3 of the present invention;

[0027] Figure 4The spectrum of the material prepared in Example 3 of the present invention under 254 nm excitation at 10 °C intervals from -150 °C to 300 °C;

[0028] Figure 5 The spectrum of the material prepared in Example 3 of the present invention under 365 nm excitation at 10 °C intervals from -150 °C to 300 °C;

[0029] Figure 6 The spectrum of the material prepared in Example 3 of the present invention under 980 nm excitation at 10 °C intervals from -150 °C to 300 °C;

[0030] Figure 7 The thermal emission spectrum of the material prepared in Example 3 of the present invention was obtained by placing it on a heating stage at 300°C after pre-excitation at 254 nm for 1 min.

[0031] Figure 8 Luminescence photographs of the material prepared in Example 3 of the present invention from -150°C to 300°C under 254nm excitation;

[0032] Figure 9 Luminescence photographs of the material prepared in Example 3 of the present invention from -150°C to 300°C under 365nm excitation;

[0033] Figure 10 Luminescence photographs of the material prepared in Example 3 of the present invention from -150°C to 300°C under 9nm excitation;

[0034] Figure 11 The thermal emission photograph of the material prepared in Example 3 of the present invention after being pre-excited at 254 nm for 1 min and placed on a heating stage at 300 °C. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] The chemical formula of the material prepared by this invention is: CaWO4:x%Yb 3+ Er 3+ Eu 3+ ; among which, 0 <x≤2。

[0037] Example 1

[0038] The preparation method of the multimode intelligent response luminescent material in Example 1 includes the following steps:

[0039] Step (1): Mix CaO, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol at a molar ratio of 1:1:0.004:0.004:0.004 and grind them evenly. Press the evenly mixed white powder under 120MPa for 1min to form a sheet and obtain a round sheet-like reactant.

[0040] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:5, anhydrous ethanol covering the balls, a ball milling speed of 700 r / min, and a ball milling time of more than 6 hours;

[0041] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1000℃ in air atmosphere. The heating rate is 4℃ / min, the holding time is 5h, and the mixture is air-cooled to room temperature to obtain the multimode intelligent responsive luminescent material CaWO4:x%Yb. 3+ Er 3+ Eu 3+ x = 0.4.

[0042] Example 2

[0043] The preparation method of the multimode intelligent response luminescent material in Example 2 includes the following steps:

[0044] Step (1): Mix CaO, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol at a molar ratio of 1:1:0.008:0.008:0.008 and grind them evenly. Press the evenly mixed white powder under 140MPa for 2 minutes to form a sheet and obtain a round sheet-like reactant.

[0045] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:10, anhydrous ethanol covering the balls, a ball milling speed of 750 r / min, and a ball milling time of more than 6 hours;

[0046] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1100℃ in air atmosphere. The heating rate is 6℃ / min, the holding time is 7h, and the material is air-cooled to room temperature to obtain the multimode intelligent responsive luminescent material CaWO4:x%Yb. 3+ Er 3+ Eu 3+ x = 0.8.

[0047] Example 3

[0048] The preparation method of the multimode intelligent response luminescent material in Example 3 includes the following steps:

[0049] Step (1): Mix CaO, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol at a molar ratio of 1:1:0.01:0.01:0.01 and grind them evenly. Press the evenly mixed white powder under 150MPa for 3 minutes to form a sheet and obtain a round sheet-like reactant.

[0050] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:20, anhydrous ethanol covering the balls, a ball milling speed of 800 r / min, and a ball milling time of more than 6 hours;

[0051] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1050℃ in air atmosphere. The heating rate is 5℃ / min, the holding time is 6h, and the mixture is air-cooled to room temperature to obtain the multimode intelligent responsive luminescent material CaWO4:x%Yb. 3+ Er 3+ Eu 3+ , x = 1.

[0052] Example 4

[0053] The preparation method of the multimode intelligent response luminescent material in Example 4 includes the following steps:

[0054] Step (1): Mix CaCO3, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol in a molar ratio of 1:1:0.015:0.015:0.015 and grind them evenly. Press the evenly mixed white powder under 120MPa for 4 minutes to form a sheet and obtain a round sheet-like reactant.

[0055] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:30, anhydrous ethanol covering the balls, a ball milling speed of 850 r / min, and a ball milling time of more than 6 hours;

[0056] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1050℃ in air atmosphere. The heating rate is 5℃ / min, the holding time is 5h, and the material is air-cooled to room temperature to obtain a multimode intelligent responsive luminescent material: CaWO4:x%Yb. 3+ Er 3+ Eu 3+ x = 1.5.

[0057] Example 5

[0058] The preparation method of the multimode intelligent response luminescent material in Example 5 includes the following steps:

[0059] Step (1): Mix CaCO3, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol at a molar ratio of 1:1:0.018:0.018:0.018 and grind them evenly. Press the evenly mixed white powder under 130MPa for 5 minutes to form a sheet and obtain a round sheet-like reactant.

[0060] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:10, anhydrous ethanol covering the balls, a ball milling speed of 900 r / min, and a ball milling time of more than 6 hours;

[0061] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1000℃ in air atmosphere. The heating rate is 6℃ / min, the holding time is 5h, and the material is air-cooled to room temperature to obtain a multimode intelligent responsive luminescent material: CaWO4:x%Yb. 3+ Er 3+ Eu 3+ x = 1.8.

[0062] Example 6

[0063] The preparation method of the multimode intelligent response luminescent material in Example 6 includes the following steps:

[0064] Step (1): Mix CaCO3, WO3, Yb2O3, Er2O3 and Eu2O3 in anhydrous ethanol at a molar ratio of 1:1:0.02:0.02:0.02 and grind them evenly. Press the evenly mixed white powder under 150MPa for 5 minutes to form a sheet and obtain a round sheet-like reactant.

[0065] The aforementioned grinding method is ball milling, with a ball-to-material ratio of 1:10, anhydrous ethanol covering the balls, a ball milling speed of 900 r / min, and a ball milling time of more than 6 hours;

[0066] Step (2): Place the reactants obtained in step (1) into an alumina crucible, put it into a tube sintering furnace, and sinter at a high temperature of 1000℃ in air atmosphere. The heating rate is 5℃ / min, the holding time is 5h, and the material is air-cooled to room temperature to obtain a multimode intelligent responsive luminescent material: CaWO4:x%Yb. 3+ Er 3+ Eu 3+ x = 2.

[0067] Example 7

[0068] This embodiment 7 provides an application of a multi-mode intelligent response luminescent material, which is applied to a screen printing anti-counterfeiting environment.

[0069] After grinding the powder of any of the multi-mode intelligent responsive luminescent materials obtained in Examples 1-6, it is mixed evenly with ink and then coated onto paper. Different wavelengths of light produce different colors, and it exhibits temperature responsiveness. In this example, the anti-counterfeiting symbol is an "8". Sample powder is mixed into different lines, and the luminescent number will only appear when illuminated with light of a suitable wavelength. The color varies with different wavelengths, and there is a fixed color change with temperature variations.

[0070] Example Analysis

[0071] The multimode smart luminescent material obtained in Example 3 was analyzed using an X-ray diffractometer, and the results are as follows: Figure 1 As shown. By Figure 1 As can be seen, the diffraction pattern is consistent with the standard diffraction pattern of CaWO4 (PDF#01-0806 in the figure), indicating that the addition of three ions did not cause the formation of a new phase. This proves that the CaWO4 pure phase in the multimode intelligent luminescent material obtained in this embodiment has good chemical stability.

[0072] See Figure 2 The emission spectra of the multimode intelligent responsive luminescent material prepared in Example 3 of this invention were tested at excitation wavelengths of 250 nm, 379 nm, and 980 nm. Figure 2 It can be seen that the emission wavelength peaks are located at 615nm, 552nm, and the green light wavelength range of approximately 500nm–600nm. At detection wavelengths of 615nm and 552nm, the excitation spectrum peaks are 250nm and 379nm, respectively, consistent with Er... 3+ Eu 3+ Typical emission lines and excitation wavelengths, and Yb 3+ Er 3+ Upconversion pairs emit light.

[0073] Furthermore, the multimode intelligent responsive luminescent material prepared in Example 3 was placed under sunlight and under 254nm, 365nm ultraviolet lamps and 980nm laser light, respectively, and photographs were taken. Figure 3 It appears as a white solid under sunlight, glows red under 254nm illumination, yellow under 365nm illumination, and green under 980nm illumination;

[0074] Furthermore, the multimode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 254nm ultraviolet light excitation and heated uniformly from -150℃ to 300℃. Spectra at several temperature points were collected. Figure 4As the temperature increases, the luminescence intensity of the parent material weakens, and the peak intensity around 600 nm weakens. The multimode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 365 nm ultraviolet light excitation and heated uniformly from -150°C to 300°C. Spectra at several temperature points were collected. Figure 5 As the temperature increases, the peak intensity around 500 nm changes in the opposite direction, while the peak intensity around 600 nm weakens. The multi-mode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 980 nm laser irradiation and heated uniformly from -150°C to 300°C. Spectra at several temperature points were collected. Figure 6 As the temperature increases, the peak intensity around 500 nm changes in the opposite direction, while the overall intensity remains unchanged. The multimode intelligent responsive luminescent material prepared in Example 3 was pre-excited with 254 nm ultraviolet light for 1 min, then placed on a heating stage at 300°C for instantaneous heating and spectral collection. Figure 7 As the temperature instantly reaches 300℃, the peak intensity at around 600nm increases instantaneously.

[0075] Furthermore, the multimode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 254nm ultraviolet light excitation and heated uniformly from -150℃ to 300℃. Images were taken at several temperature points to obtain... Figure 8 As the temperature rises, the color changes from red at low temperatures to pink at room temperature, and then to yellow at high temperatures, similar to... Figure 4 Consistent; the multimode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 365nm ultraviolet light excitation and heated uniformly from -150℃ to 300℃. Images were taken at several temperature points to obtain... Figure 9 As the temperature rises, the color changes from bright yellow at low temperatures to green at high temperatures, and... Figure 5 Consistent; the multimode intelligent responsive luminescent material prepared in Example 3 was placed on a heating stage under 980nm laser irradiation and heated uniformly from -150℃ to 300℃. Images were taken at several temperature points to obtain... Figure 10 As temperature increases, the upconversion green color does not change significantly, unlike... Figure 6 Consistent; the multimode intelligent responsive luminescent material prepared in Example 3 was pre-excited with 254nm ultraviolet light for 1 min, then placed on a heating stage at 300℃, and the spectrum was collected by instantaneous heating. Figure 11 As the temperature instantly reaches 300℃, energy is released, and the emitted light is red. As the energy is released, the red color gradually fades, becoming... Figure 7 Consistent.

[0076] Analysis of the foregoing results shows that, in environments ranging from low to high temperatures, the multimode intelligent luminescent material exhibits red, pink, and yellow fluorescence changes under 254nm UV light irradiation, and changes from bright yellow to green under 365nm UV light irradiation. However, under 980nm UV light irradiation, the color does not change significantly, remaining green due to the upconversion pair. The prepared material, after pre-excitation with a 254nm UV light for 1 minute, instantaneously releases energy and emits red fluorescence at 300°C. Therefore, the luminescent material obtained in this invention exhibits different colors under different excitations, multi-color changes in temperature response, and good energy storage effect, achieving a multimode intelligent response effect and realizing multi-color and multi-mode response technology within the same material.

[0077] The present invention has been described in detail with reference to the foregoing embodiments. Those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-mode intelligent responsive luminescent material, characterized in that, The chemical formula of the multimode intelligent response luminescent material is CaWO4:x%Yb 3+ Er 3+ Eu 3+ ;in, 0.4≤x≤2。 2. An application of the multi-mode intelligent responsive luminescent material according to claim 1, characterized in that, The multi-mode intelligent response luminescent material is applied to screen printing anti-counterfeiting environments.

3. The application according to claim 2, characterized in that, The multimode intelligent responsive luminescent material exhibits changes in fluorescence—red, pink, and yellow—under 254 nm ultraviolet light irradiation.

4. The application according to claim 2, characterized in that, The multi-mode intelligent response luminescent material changes from bright yellow to green under 365 nm ultraviolet light irradiation.

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