Up-conversion luminescence time sequence regulation color-changing material, color-changing ink and preparation method and application thereof

Abstract

The invention discloses an up-conversion luminescence time sequence regulation color-changing material, color-changing ink and a preparation method and application thereof, the chemical general formula of the material is SrMoO4: xYb < 3 + >, yHo < 3 + > and zNa < + >, x is the molar doping amount of Yb < 3 + >, y is the molar doping amount of Ho < 3 + >, z is the molar doping amount of Na < + >, 0.10 < = x < = 0.40, 0.01 < = y < = 0.03, and 0.21 < = z < = 0.31. According to the material, under the condition of charge compensation ion Na < + > co-doping, the solid solubility of sensitizer ions Yb < 3 + > in SrMoO4 crystal lattices is remarkably improved, and under the condition of Na < + > excessive charge compensation, the material is remarkably superior to the upconversion luminescence effect of other charge compensation enhanced heterovalent doping systems reported in literatures; the color-changing ink for advanced dynamic anti-counterfeiting and the application method thereof are designed and developed by combining the remarkably enhanced up-conversion luminescence and the excellent time sequence regulation color-changing characteristic of the material, and the color-changing ink has a wide application prospect in the field of dynamic fluorescent anti-counterfeiting.

Description

Technical Field

[0001] This invention relates to the field of rare earth luminescent materials technology, specifically to an upconversion luminescence timing-controlled color-changing material, a color-changing ink, and their preparation methods and applications. Background Technology

[0002] Currently, advanced anti-counterfeiting technology has become a key requirement for ensuring product safety. Fluorescent anti-counterfeiting, due to its low cost and convenient detection, is widely used in packaging, certificates, and many other fields. However, traditional fluorescent anti-counterfeiting often employs a static mode of "single-color excitation + fixed emission," whose luminescent characteristics are easily analyzed and imitated, resulting in relatively limited anti-counterfeiting security.

[0003] Upconversion luminescence exhibits characteristic responses to different emission modes and external environments (such as temperature and pressure), making it particularly suitable for developing advanced dynamic fluorescent anti-counterfeiting technologies. In particular, time-controlled color-changing upconversion luminescence not only provides significant color-changing effects but is also simple to apply. However, currently widely studied fluoride materials still suffer from poor chemical and thermal stability, complex preparation processes, and high costs. In contrast, strontium molybdate (SrMoO4) possesses good chemical stability and low phonon energy (~850 cm⁻¹). -1 It possesses advantages such as good optical transmittance, and its material preparation process is simple, requiring only a simple solid-state method. However, the sensitizer Yb... 3+ The doping concentration in intrinsic strontium molybdate lattices is strictly limited (Peng Du, Curr. Appl. Phys. 2015, 15: 1576; Abhishek Kumar Soni, Solid State Sci. 2016, 58:129; Dangyu Li, J. Alloy. Compd. 2013, 550: 509; Xin Liu, Sensor Actuat A-Phys. 2020, 315: 112287; Yan Wang, J. Mater. Chem. B, 2013, 1: 2056; WeifuSun, Phys. Chem. Chem. Phys. 2016, 18: 33320; Thulitha M, Dalton Tans. 2024,53: 1014; Chang Sung Lim, Mater. Res. Bull. 2013, 48: 3805), which greatly limits the development and application of rare-earth activated strontium molybdate upconversion luminescent materials. Studies have shown that when Yb in the SrMoO4 ​​lattice... 3+ When the doping concentration exceeds 3 mol%, Yb 3+Decreased interionic spacing induces concentration quenching; simultaneously, high concentrations of Yb 3+ Doping also inhibits lattice symmetry breaking at active sites, leading to a decrease in upconversion luminescence intensity (Ankur Shandilya, Mater. Chem. Phys. 2021, 264: 124441; Ankur Shandilya, J. Mater. Sci. 2021, 56:12716.). Although previous studies have improved upconversion luminescence intensity to some extent by introducing charge compensators, Yb 3+ The fundamental problem of low doping concentration has not yet been effectively solved (Hui Zhang, J. Mater. Chem. C, 2019, 7: 15007.). Summary of the Invention

[0004] This invention addresses the aforementioned problems by researching and designing an upconversion luminescence timing-controlled color-changing material, a color-changing ink, its preparation method, and its applications. The technical means employed in this invention are as follows: A time-regulated upconversion luminescence color-changing material, the general chemical formula of which is SrMoO4:xYb 3+ ,yHo 3+ ,zNa + , where x is Yb 3+ The molar doping amount, y is Ho 3+ The molar doping amount, z is Na + The molar doping amount is such that 0.10≤x≤0.40, 0.01≤y≤0.03, and 0.21≤z≤0.31.

[0005] Furthermore, the material is a sensitized ion Yb 3+ Activated ions Ho 3+ and charge-compensating ions Na + Co-doped tetragonal SrMoO4 ​​polycrystalline powder.

[0006] Furthermore, z≥x+y, preferably z>x+y, in Na + Under conditions of excess charge compensation, Ho 3+ The steady-state green upconversion luminescence intensity in the 530-580 nm band and the steady-state red upconversion luminescence intensity in the 630-690 nm band were both significantly improved.

[0007] Furthermore, x is preferably 0.20, y is preferably 0.01, z is preferably 0.26, and the excitation wavelength is preferably 980nm.

[0008] The upconversion luminescence time-controlled color-changing material of this invention can emit green upconversion luminescence in the 530-580 nm band and red upconversion luminescence in the 630-690 nm band under excitation at any wavelength from 900 to 1050 nm. The material employs time-controlled technology, allowing its upconversion luminescence color to gradually change from red to green.

[0009] A method for preparing an upconversion luminescence time-controlled color-changing material, used to prepare the upconversion luminescence time-controlled color-changing material of the present invention, employs a high-temperature solid-state method and includes the following steps: S1: Weigh out the strontium source compound, holmium source compound, ytterbium source compound, sodium source compound and molybdenum source compound according to the molar ratio of Sr:Ho:Yb:Na:Mo=(1-xyz):y:x:z:1, where 0.10≤x≤0.40, 0.01≤y≤0.03, 0.21≤z≤0.31; S2: Grind the weighed raw materials until they are evenly mixed, and then dry them. S3: Calcine the raw material in air for 2-3 hours at a temperature of 700-900℃; S4: Cool and grind the calcined material to obtain an upconversion luminescence timing-controlled color-changing material.

[0010] Further, in step S2, grinding is carried out by ball milling, and drying is carried out in a vacuum drying oven at 60~80℃ for 1 h; in step S3, the calcination temperature is 800℃, the calcination time is 2.5 h, and the heating rate is 5-10℃ / min, preferably 10℃ / min.

[0011] A color-changing ink, comprising the upconversion luminescence timing-controlled color-changing material described in this invention.

[0012] A method for preparing a color-changing ink involves uniformly dispersing the upconversion luminescence timing-controlled color-changing material described in this invention into the ink.

[0013] Furthermore, the weight ratio of the upconversion luminescence timing-controlled color-changing material to the ink is 1:1.5.

[0014] An application of the color-changing ink described in this invention in the field of anti-counterfeiting.

[0015] Furthermore, when the color-changing ink is applied to the field of anti-counterfeiting, the color-changing ink is printed on a substrate, which may be paper, glass, plastic or metal, and the printing method is selected from screen printing, flexographic printing or manual printing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: First, in charge-compensated ions Na +Under co-doping conditions, the sensitizer ion Yb 3+ The solid solubility in the SrMoO4 ​​lattice is significantly improved, which is superior to that of Yb in the prior art. 3+ Doping concentration (typically below 10 mol%).

[0017] Second, in Na + Under conditions of excess charge compensation, Ho 3+ The steady-state green upconversion luminescence in the 530-580nm band is improved by more than 348,800%, while the red steady-state upconversion luminescence intensity in the 630-690nm band is improved by more than 245,000%, which is significantly better than the effect of other charge-compensated enhancement of upconversion luminescence in heterovalent doped systems reported in the literature (usually the enhancement is less than 10,000%).

[0018] Third, by combining the material's significantly enhanced upconversion luminescence and its excellent time-controlled color-changing characteristics, color-changing inks and application methods that can be used for advanced dynamic anti-counterfeiting have been designed and developed, showing broad application prospects in the field of dynamic fluorescent anti-counterfeiting. Attached Figure Description

[0019] Figure 1 The XRD spectrum of the upconversion luminescence timing-controlled color-changing material of Embodiment 1 of the present invention is shown.

[0020] Figure 2 The images show a single-particle SEM image and an elemental EDS distribution image of the upconversion luminescence timing-controlled color-changing material of Embodiment 1 of the present invention.

[0021] Figure 3 The steady-state upconversion emission spectrum of the upconversion emission timing-controlled color-changing material of Embodiment 1 of the present invention is shown under 980nm excitation.

[0022] Figure 4 The upconversion luminescence timing-controlled color-changing material of Embodiment 1 of the present invention and monoclinic Yb2Mo4O 15 10%Lu 3 + / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho 3+ Comparison of steady-state upconversion emission spectra of phosphors under the same excitation conditions.

[0023] Figure 5 The normalized time-controlled emission spectrum of the upconversion luminescence timing-controlled color-changing material of Embodiment 1 of the present invention under 980nm excitation.

[0024] Figure 6 The ratio of red to green emission intensity of the upconversion luminescence timing-controlled color-changing material in Embodiment 1 of the present invention under 980nm excitation.

[0025] Figure 7 The colorimetric change of the upconversion luminescence of the upconversion luminescence timing-controlled color-changing material of Embodiment 1 of the present invention under 980nm excitation.

[0026] Figure 8 The XRD spectrum of the upconversion luminescence timing-controlled color-changing material of Embodiment 2 of the present invention is shown.

[0027] Figure 9 The steady-state upconversion emission spectrum of the upconversion emission timing-controlled color-changing material of Embodiment 2 of the present invention is shown under 980nm excitation.

[0028] Figure 10 The steady-state upconversion emission spectra of the upconversion emission timing-controlled color-changing material of Embodiment 2 of the present invention and the upconversion emission timing-controlled color-changing material disclosed in the preferred embodiment are obtained under the same excitation conditions.

[0029] Figure 11 The XRD spectrum of the upconversion luminescence timing-controlled color-changing material of Embodiment 3 of the present invention is shown.

[0030] Figure 12 The steady-state upconversion emission spectrum of the upconversion emission timing-controlled color-changing material of Embodiment 3 of the present invention is shown under 940nm excitation.

[0031] Figure 13 The upconversion luminescence timing-controlled color-changing material of Embodiment 3 of the present invention and monoclinic Yb2Mo4O 15 10%Lu 3 + / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho 3+ Comparison of steady-state upconversion emission spectra of phosphors under the same excitation conditions.

[0032] Figure 14 This is the XRD spectrum of the material in Comparative Example 1 of this invention.

[0033] Figure 15 The steady-state upconversion emission spectra of the material in Comparative Example 1 and the upconversion emission timing-controlled color-changing material in Example 1 of the present invention are compared under the same excitation.

[0034] Figure 16 This is the XRD spectrum of the material in Comparative Example 2 of this invention.

[0035] Figure 17 The steady-state upconversion emission spectra of the material in Comparative Example 2 and the upconversion emission timing-controlled color-changing material in Example 1 are compared under the same excitation. Detailed Implementation

[0036] Example 1 The upconversion luminescence timing-controlled color-changing material disclosed in this embodiment is prepared using the following method: SrCO3, Ho2O3, Yb2O3, Na2CO3, and MoO3 were weighed according to the molar ratio of Sr:Ho:Yb:Na:Mo = 0.53:0.01:0.20:0.26:1. The weighed raw materials were placed in an agate mortar, mixed, and ground for 0.5 h. The mixture was then dried in a vacuum drying oven at 60-80℃ for 1 h to remove ethanol. The mixture was then calcined in air at 800℃ for 2.5 h at a heating rate of 10℃ / min to obtain the target product. After calcination, the sample was cooled to room temperature in the furnace and then thoroughly ground to obtain the target upconversion luminescent material.

[0037] Figure 1 The image shows the XRD pattern of the upconversion luminescence timing-controlled color-changing material disclosed in this embodiment. As can be seen from the figure, the material has a tetragonal SrMoO4 ​​structure.

[0038] Figure 2 This image shows a single-particle SEM image and an elemental EDS distribution image of the upconversion luminescence timing-controlled color-changing material disclosed in this embodiment. As can be seen from the image, the sensitizer ion Yb... 3+ Activator ions Ho 3+ and charge-compensating ions Na + It has been successfully incorporated into the SrMoO4 ​​lattice.

[0039] Figure 3 This embodiment discloses the steady-state upconversion emission spectrum of an upconversion emission time-controlled color-changing material under 980 nm excitation. As shown in the figure, this material emits typical Ho in the visible band. 3 +Green light ( 5 S2 / 5 F4→ 5 I8 jump) and red light ( 5 F5 → 5 The I8 transition is emitted, with red light being stronger than green light.

[0040] Figure 4 The upconversion luminescence timing-controlled color-changing material disclosed in this embodiment is a monoclinic Yb2Mo4O 15 10%Lu 3+ / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho 3+ A comparison of the steady-state upconversion emission spectra of phosphors under the same excitation conditions was conducted. The results show that the total upconversion emission intensity of this material is 4.5 times and 6.3 times that of the two materials mentioned above, respectively. This is due to the monoclinic Yb₂Mo₄O₂... 1510%Lu 3+ / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho 3+ It is currently recognized as having excellent performance. 3+ Based on the upconversion luminescent material, the material disclosed in this embodiment exhibits superior upconversion luminescent properties.

[0041] Figures 5-7 The figures show the normalized time-controlled emission spectrum, red-green emission intensity ratio, and corresponding chromaticity changes of the upconversion luminescence time-controlled color-changing material disclosed in this embodiment under 980 nm excitation. As shown in the figure, as the pulse excitation time decreases from 10 ms to 0.1 ms, the red light emission intensity gradually decreases, while the green light emission intensity gradually increases. The red-green emission intensity ratio correspondingly increases from 0.25 to 3.08, while the dominant wavelength shifts from 578 nm to 553 nm (blue shift). These changes cause the upconversion emission color to change significantly from red to green, fully demonstrating its excellent time-controlled luminescence color-changing performance.

[0042] This embodiment is the optimal embodiment, in Na + Under conditions of excess charge compensation, Ho 3+ The steady-state green upconversion luminescence in the 530-580 nm band is improved by more than 348,800%, while the red steady-state upconversion luminescence intensity in the 630-690 nm band is improved by more than 245,000%, which is significantly better than the effect of other charge-compensated enhancement of upconversion luminescence in heterovalent doped systems reported in the literature (usually the enhancement is less than 10,000%).

[0043] Example 2 SrCO3, Ho2O3, Yb2O3, Na2CO3, and MoO3 were weighed according to the molar ratio of Sr:Ho:Yb:Na:Mo = 0.58:0.01:0.20:0.21:1. The weighed raw materials were placed in an agate mortar, mixed, and ground for 0.5 h. The mixture was then dried in a vacuum drying oven at 60-80℃ for 1 h to remove ethanol. The mixture was then calcined in air at 800℃ for 2.5 h at a heating rate of 10℃ / min to obtain the target product. After calcination, the mixture was cooled to room temperature in the furnace, and the sample was thoroughly ground to obtain the target upconversion luminescent material.

[0044] Figure 8 The image shows the XRD pattern of the upconversion luminescence timing-controlled color-changing material disclosed in this embodiment. As can be seen from the figure, the material has a tetragonal SrMoO4 ​​structure.

[0045] Figure 9This embodiment discloses the steady-state upconversion emission spectrum of an upconversion emission time-controlled color-changing material under 980 nm excitation. As shown in the figure, this material emits typical Ho in the visible band. 3+ Green light ( 5 S2 / 5 F4→ 5 I8 jump) and red light ( 5 F5 → 5 The I8 transition is emitted, with red light being stronger than green light.

[0046] Figure 10 The figures show the steady-state upconversion luminescence spectra of the upconversion luminescence timing-controlled color-changing material disclosed in this embodiment and the material disclosed in the best embodiment under the same excitation conditions. As can be seen from the figures, the material in this embodiment has good upconversion luminescence characteristics, but its green and red light emission intensities are reduced by 31% and 36% respectively compared to Example 1.

[0047] Example 3 The upconversion luminescence timing-controlled color-changing material in this embodiment was prepared using the method described in Example 1.

[0048] Figure 11 The image shows the XRD pattern of the upconversion luminescence timing-controlled color-changing material disclosed in this embodiment. As can be seen from the figure, the material has a tetragonal SrMoO4 ​​structure.

[0049] Figure 12 This embodiment discloses the steady-state upconversion emission spectrum of an upconversion emission time-controlled color-changing material under 940 nm excitation. As shown in the figure, this material emits typical Ho in the visible band. 3+ Green light ( 5 S2 / 5 F4→ 5 I8 jump) and red light ( 5 F5 → 5 The I8 transition is emitted, with red light being stronger than green light.

[0050] Figure 13 The upconversion luminescence timing-controlled color-changing material disclosed in this embodiment is a monoclinic Yb2Mo4O 15 10%Lu 3 + / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho 3+ Comparison of steady-state upconversion emission spectra of phosphors excited at 940 nm. The results show that monoclinic Yb₂Mo₄O₂... 15 10%Lu 3+ / 1%Ho 3+ and hexagonal phase NaYF4:20%Yb 3+ / 2%Ho3+ The luminescence intensity of the phosphor is weaker than that under 980 nm excitation. The total upconversion luminescence intensity of this material is 7.7 times and 148 times that of the two materials mentioned above, respectively.

[0051] Comparative Example 1 The only difference between the preparation method used for this comparative material and the example is that Na... + The doping concentration is 0 mol.

[0052] Figure 14 This is the XRD spectrum of the material disclosed in this comparative example. As can be seen from the figure, Yb₂Mo₃O₃... 12 The presence of impurity phases indicates the absence of charge-compensating Na+ ions. + Under doping conditions, Yb 3+ It cannot be effectively incorporated into the tetragonal SrMoO4 ​​lattice.

[0053] Figure 15 The figure shows a comparison of the steady-state upconversion emission spectra of the material disclosed in this comparative example and the material of Example 1 under the same excitation. As can be seen from the figure, the emission of the comparative example material is extremely weak, with its green and red light emission intensities being 0.028% and 0.040% of those of Example 1, respectively.

[0054] Comparative Example 2 The only difference between the preparation method used for this comparative material and the example is that the calcination temperature is 600°C.

[0055] Figure 16 This is the XRD spectrum of the material disclosed in this comparative example. As can be seen from the figure, even with the introduction of charge-compensating ions Na, under unsuitable calcination temperatures... + Yb 3+ It also cannot be effectively incorporated into the tetragonal SrMoO4 ​​lattice.

[0056] Figure 17 The figures show the steady-state upconversion emission spectra of the material disclosed in this comparative example and the upconversion emission time-controlled color-changing material disclosed in Example 1 under the same excitation. As can be seen from the figure, the emission of the comparative example material is weaker, with its green and red light emission intensities being 66% and 72% of those of Example 1, respectively.

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A color-changing material with upconversion luminescence timing modulation, characterized in that, The chemical formula of the material is SrMoO4:xYb 3+ ,yHo 3+ ,zNa + , where x is Yb 3+ The molar doping amount, y is Ho 3+ The molar doping amount, z is Na + The molar doping amount is such that 0.10≤x≤0.40, 0.01≤y≤0.03, and 0.21≤z≤0.

31.

2. The upconversion luminescence timing-controlled color-changing material according to claim 1, characterized in that, The material is a sensitized ion Yb 3+ Activated ions Ho 3+ and charge-compensating ions Na + Co-doped tetragonal SrMoO4 ​​polycrystalline powder, where z≥x+y.

3. The upconversion luminescence timing-controlled color-changing material according to claim 1, characterized in that, x is 0.20, y is 0.01, and z is 0.

26.

4. A method for preparing an upconversion luminescence time-controlled color-changing material, used to prepare the upconversion luminescence time-controlled color-changing material according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Weigh out the strontium source compound, holmium source compound, ytterbium source compound, sodium source compound and molybdenum source compound according to the molar ratio of Sr:Ho:Yb:Na:Mo=(1-xyz):y:x:z:1, where 0.10≤x≤0.40, 0.01≤y≤0.03, 0.21≤z≤0.31; S2: Grind the weighed raw materials until they are evenly mixed, and then dry them. S3: Calcine the raw material in air for 2-3 hours at a temperature of 700-900℃; S4: Cool and grind the calcined material to obtain an upconversion luminescence timing-controlled color-changing material.

5. The method for preparing the upconversion luminescence timing-controlled color-changing material according to claim 4, characterized in that, In step S2, grinding is carried out by ball milling, and drying is carried out in a vacuum drying oven at 60~80℃ for 1 h; in step S3, the calcination temperature is 800℃, the calcination time is 2.5 h, and the heating rate is 5-10℃ / min.

6. A color-changing ink, characterized in that, Includes the upconversion luminescence timing-controlled color-changing material as described in any one of claims 1 to 4.

7. A method for preparing a color-changing ink, characterized in that, The upconversion luminescence timing-controlled color-changing material according to any one of claims 1-6 is uniformly dispersed into the ink.

8. The method for preparing color-changing ink according to claim 7, characterized in that, The weight ratio of the upconversion luminescence timing-controlled color-changing material to the ink is 1:1.

5.

9. The application of the color-changing ink according to any one of claims 6-8 in the field of anti-counterfeiting.

10. The application of the color-changing ink according to claim 9 in the field of anti-counterfeiting, characterized in that, The color-changing ink is printed onto a substrate, which may be paper, glass, plastic, or metal, and the printing method is selected from screen printing, flexographic printing, or manual printing.

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