A photochromic mixed phosphor material and its body color reversible control method and application

Abstract

The present invention discloses a photochromic hybrid phosphor material, a method for reversibly regulating its body color, and applications thereof, relating to the technical field of photochromic phosphors. The photochromic hybrid phosphor material comprises Na 0.5 , 0.5 , 0.03 , 3+ , + , 1.97 , + , 3+ -doped Zn2GeO4 photochromic phosphor and Sm 3+ -doped NaYb(MoO4)2 thermal radiation phosphor; The chemical formula of the Na + -doped Zn2GeO4 photochromic phosphor is Zn 1.97 Na 0.03 GeO4; The chemical formula of the Sm 3+ -doped NaYb(MoO4)2 thermal radiation phosphor is NaYb 0.5 Sm 0.5 (MoO4)2; By irradiating the hybrid phosphor with 254 nm ultraviolet light for 1 minute, the body color of the hybrid phosphor changes from white to purple; The colored hybrid phosphor returns from purple to white within 1 second under the irradiation of 980 nm near-infrared light, realizing the rapid fading of the body color of the colored phosphor powder, completing the reversible transformation, and having good reversibility and stability, making the photochromic phosphor more convenient in practical applications; Avoiding the adverse effects brought by traditional heat treatment methods and visible light reduction, it is expected to promote the application of photochromic materials in the field of optical anti-counterfeiting.

Description

Technical Field

[0001] The invention relates to the technical field of photochromic phosphors, and in particular to a photochromic mixed phosphor material and a method and application of reversible body color regulation thereof. Background Art

[0002] Counterfeit and shoddy products have gradually penetrated into all walks of life, not only causing economic losses to the country and individuals, but also counterfeit documents pose hidden dangers to national security, and counterfeit medical drugs will also seriously threaten human health. In this context, fluorescent anti-counterfeiting labels with convenient identification have received widespread attention in the industry. However, with the development of commercial phosphors, the security of anti-counterfeiting labels made based on traditional photoluminescent phosphors is also facing threats. Compared with photoluminescent phosphors, photochromic phosphors not only have rich luminescent colors but also have variable body colors. Therefore, inorganic phosphors with reversible photochromic properties have great potential in anti-counterfeiting applications.

[0003] At present, the methods for erasing the body color of photochromic phosphors mainly include heat treatment and visible light reduction. For some photochromic phosphors with low synthesis temperatures, it is not friendly to use heat treatment to achieve body color reduction. Higher heat treatment temperatures may destroy the material structure and cause the photochromic properties to disappear. If the heat treatment temperature is lowered, it will also lead to unfavorable problems such as prolonged body color reduction time or incomplete body color reduction. In addition, anti-counterfeiting labels made based on photochromic fluorescent powders need to be attached to the surface of the goods and cannot be separated from the goods at will. This means that during the reduction process using the heat treatment method, it is impossible to locally heat the label part to identify the authenticity. Instead, the entire product needs to be placed in a high-temperature atmosphere, which will damage the product to a certain extent and cause irreparable losses. Photochromic fluorescent powders that use visible light to restore body color have certain advantages over heat treatment to achieve body color reduction. However, this type of material is usually only sensitive to visible light of a certain wavelength, while light of other wavelengths cannot affect the body color of the material. This means that in order to achieve the body color change of the material, the wavelength of the light source needs to be precisely controlled. However, in actual applications, it is difficult to ensure that this specific wavelength of light source is always used, especially under complex and changeable environmental conditions. In addition, since different types of photochromic fluorescent powders require different visible light wavelengths to restore body color, it is difficult to establish a unified anti-counterfeiting standard and detection method in the industry, which is not conducive to the promotion and application of anti-counterfeiting technology and increases the risk of counterfeiting. Therefore, the application of photochromic materials in the field of anti-counterfeiting is limited. Summary of the invention

[0004] The present invention provides a photochromic mixed phosphor material and a method and application for reversibly regulating the body color thereof to solve the above problems.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] The present invention provides a photochromic mixed phosphor material, comprising: the photochromic mixed phosphor material comprising Na + Doped Zn 2 GeO 4 Photochromic phosphor and Sm 3+ Doped NaYb(MoO 4 ) 2 Thermal radiation phosphor;

[0007] The Na + Doped Zn 2 GeO 4 The chemical formula of photochromic phosphor is: Zn 1.97 Na 0.03 GeO 4 ;

[0008] The Sm 3+ Doped NaYb(MoO 4 ) 2 The chemical formula of thermal radiation phosphor is: NaYb 0.5 Sm 0.5 (MoO 4 ) 2 Phosphor.

[0009] Another aspect of the present invention provides a method for reversibly controlling the body color of a photochromic mixed phosphor material, comprising the steps of: 1.97 Na 0.03 GeO 4 Phosphor and NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The mixed phosphor material is prepared by physically mixing the phosphors in a mass ratio of 1:1. When colored by 254nm irradiation, the body color of the material gradually changes from white to purple. The body color of the colored mixed material can be restored from purple to white under 980nm near-infrared light irradiation.

[0010] Furthermore, the irradiation time at 254 nm is 1 min, and the intensity is 6 W / cm 2 .

[0011] Furthermore, the 980nm near-infrared light irradiation time is 1 second, and the intensity is 47.39W / cm 2 .

[0012] Furthermore, the Zn 1.97 Na 0.03 GeO4 The preparation method of phosphor is as follows:

[0013] ZnO and GeO 2 As the matrix material, Na 2 CO 3 As doping materials, ZnO, Na and Ge were weighed in a molar ratio of 1.97:0.03:1. 2 CO 3 ,GeO 2 After grinding and mixing, the mixed material was calcined at high temperature for 8 hours to obtain Zn 1.97 Na 0.03 GeO 4 Phosphor.

[0014] Furthermore, the NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The preparation method of phosphor is as follows:

[0015] According to the molar ratio of Na, Yb, Sm and Mo of 1:0.5:0.5:2, weigh Na 2 CO 3 , Yb 2 O 3 、Sm 2 O 3 、MoO 3 After grinding and mixing, the mixture was calcined at high temperature for 6 hours to obtain NaYb 0.5 Sm 0.5 (MoO 4 ) 2 Thermal radiation phosphor.

[0016] Furthermore, the purity of ZnO is 99.99%, and the purity of GeO 2 The purity is 99.99%, Na 2 CO 3 The purity is 99.8%, Yb 2 O 3 The purity is 99.99%, Sm 2 O 3 The purity of MoO is 99.99%. 3 The purity is 99.5%.

[0017] Furthermore, the high-temperature calcination is specifically carried out as follows: placing the mixed material in an alumina crucible and placing it in a muffle furnace, and calcining it at 1150° C. for 8 hours in an air atmosphere.

[0018] Further, the specific method of high-temperature calcination is as follows: place the mixed materials in an alumina crucible and put it in a muffle furnace, and calcine at 900 °C for 6 h in an air atmosphere.

[0019] Another aspect of the present invention provides the application of the photochromic mixed phosphor material in anti-counterfeiting.

[0020] The beneficial effects of the present invention are as follows:

[0021] In the photochromic mixed phosphor material disclosed in the present invention, by irradiating the mixed powder with 254 nm ultraviolet light for 1 minute, in the mixed phosphor, the oxygen vacancies of Zn 1.97 Na 0.03 GeO 4 phosphor capture the excited single electrons to form color centers, and these color centers will cause color changes in the absorption of visible light, and the body color of the mixed phosphor material changes from white to purple; after the colored mixed material is irradiated with 980 nm near-infrared light, due to NaYb in the mixed phosphor 0.5 Sm 0.5 (MoO 4 ) 2 in the thermal radiation of the phosphor, Yb 3+ absorbs energy and transfers it to Sm 3+ , and the dense energy level distribution of Sm 3+ results in a large amount of heat being released by non-radiative relaxation, and this heat will be transferred to the colored Zn 1.97 Na 0.03 GeO 4 phosphor, so that the electrons in the color centers are thermally excited and released. Therefore, the body color of the mixed phosphor material can be restored from purple to white within 1 second, realizing the rapid fading of the body color of the colored photochromic phosphor powder, completing the reversible transformation, and having good reversibility and stability, making the photochromic phosphor more convenient in practical applications; using the photochromic mixed phosphor material of the present invention does not need to rely on visible light for reduction, getting rid of the dependence on a specific visible light wavelength for traditional visible light reduction, thus overcoming the limitations of visible light reduction and improving the reliability and stability of the anti-counterfeiting effect. This photochromic mixed phosphor material also does not need heat treatment for body color reduction, and can avoid the adverse effects brought by traditional heat treatment methods. The body color of this photochromic phosphor has the characteristics of reversible regulation, and is expected to promote the application of photochromic materials in the field of optical anti-counterfeiting. Description of the Drawings

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 3mol%Na + Doped Zn 2 GeO 4 Diffuse reflectance spectra of photochromic phosphor before and after irradiation with 254nm light;

[0024] Figure 2 3mol%Na + Doped Zn 2 GeO 4 Diffuse reflectance spectra of photochromic phosphors measured after multiple irradiation and heat treatment;

[0025] Figure 3 for Na + Doped Zn 2 GeO 4 Electron paramagnetic resonance (EPR) spectra of the photochromic phosphor (ZGN) measured before and after irradiation with 254nm UV light;

[0026] Figure 4 For NaYb 0.5 Sm 0.5 (MoO 4 ) 2 Diagram of heat generation mechanism of thermal radiation phosphor;

[0027] Figure 5 This is a process effect diagram of the photochromic hybrid phosphor material prepared in Example 1 of the present invention from body color to color change and then to body color restoration ( Figure 5 (a) is Na + Doped Zn 2 GeO 4 Photochromic phosphor and NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The effect picture of thermal radiation phosphor after mixing; Figure 5 (b) is the effect of the mixed phosphor material after irradiation with 254nm ultraviolet light for 1 minute; Figure 5 (c) The sample that has achieved photochromic properties is illuminated by a 980 nm laser at 47.39 W / cm 2 The effect diagram after irradiation with power density of 1s). DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The principle involved in the present invention is:

[0030] The present invention prepares Na + Doped Zn 2 GeO 4 Photochromic phosphor and NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The mixed phosphor after physical mixing of thermal radiation phosphor can be Na + Doped Zn 2 GeO 4 Free electrons are generated in the photochromic phosphor and then captured by oxygen vacancies to form oxygen vacancies (color centers) carrying single electrons. The generation of color centers changes the material's absorption of visible light. Therefore, the color of the photochromic phosphor changes significantly from white to purple after being irradiated with 254nm. When the colored mixed sample is irradiated with 980nm near-infrared light, the NaYb 0.5 Sm 0.5 (MoO 4 ) 2 Yb in thermal radiation phosphor 3+ It has a large absorption cross section for 980nm photons, so it can absorb energy efficiently, and the absorbed energy can be transferred to Sm through energy transfer. 3+ , and Sm 3+ The denser energy level distribution allows electrons at high energy levels to return to the ground state through non-radiative relaxation. This non-radiative relaxation process releases a lot of heat, which can cause the Zn in the mixed sample to 2 GeO 4 The single electron in the center of the photochromic fluorescent pink is released, so that the absorption of visible light by the photochromic material returns to the state before coloring, so the body color can be restored from purple to white. The mechanism of 980nm near-infrared light restoring the body color of the photochromic material is as follows: Figure 4 shown.

[0031] Example

[0032] Embodiment 1:

[0033] A photochromic mixed phosphor material is prepared according to the following steps:

[0034] S1: High-purity zinc oxide and germanium oxide were used as matrix materials, and sodium carbonate was used as doping material. 0.7979 g, 0.5232 g, and 0.0079 g of Zn, Na, and Ge were weighed in a molar ratio of 1.97:0.03:1, respectively. After being fully ground and mixed, they were placed in an air atmosphere at 1150°C and calcined for 8 hours to obtain 3 mol% Na + Doped Zn 2 GeO 4 (Zn 1.97 Na 0.03 GeO 4 ) Photochromic phosphor;

[0035] S2: Sodium carbonate, ytterbium oxide, samarium oxide, and molybdenum trioxide were used as starting materials, and the molar ratio of the elements Na, Yb, Sm, and Mo was 1:0.5:0.5:2. 0.2120 g, 0.3941 g, 0.3488 g, and 1.1516 g were weighed respectively. After being fully ground and mixed, they were placed in an air atmosphere at 900 °C and calcined for 6 hours to obtain NaYb 0.5 Sm 0.5 (MoO 4 ) 2 Thermal radiation phosphor;

[0036] S3: The two phosphors obtained in S1 and S2 were placed in an agate mortar at a mass ratio of 1:1 for physical mixing for 30 minutes to prepare a photochromic mixed phosphor material.

[0037] The Na prepared in S1 was measured using a spectrophotometer UV-2600 with an integrating sphere. + Doped Zn 2 GeO 4 (Zn 1.97 Na 0.03 GeO 4 ) The diffuse reflectance spectrum of the photochromic phosphor before and after irradiation at 254nm is as follows Figure 1 As shown, in Figure 1 It can be seen that compared with the diffuse reflectance spectrum before irradiation with 254nm (solid line), the phosphor after irradiation with 254nm produces obvious absorption in the visible light region, and the absorption is uneven. Figure 2 As shown by Figure 2 It can be seen that whenever Zn 1.97 Na 0.03 GeO 4When the phosphor is irradiated by 254nm light, the reflectivity of the diffuse reflection spectrum will decrease unevenly in the visible light region and the diffuse reflection curves will basically overlap. 1.97 Na 0.03 GeO 4 After the phosphor was heat treated (200°C), the reflectivity of the diffuse reflectance spectrum measured returned to its initial state, indicating that the photochromic properties of the phosphor material have good reversibility; when the phosphor was irradiated at 254nm, its body color gradually changed from white to purple, and the colored phosphor was heat treated at 200°C and its body color was able to recover from purple to white, indicating that the material has good stability after repeated irradiation and heat treatment.

[0038] Na + Doped Zn 2 GeO 4 The electron paramagnetic resonance (EPR) spectra of the photochromic phosphor (ZGN) measured before and after irradiation with 254nm UV light are shown in Figure 2. Figure 3 As shown, Na + Doped Zn 2 GeO 4 Compared with the EPR curve of the photochromic phosphor, the signal intensity in the EPR curve of the phosphor after ultraviolet irradiation increases significantly, which means that the defects in the material capture the photogenerated single electron; the EPR signal at g = 2.00 can be attributed to the single-electron oxygen vacancy formed by the capture of a single electron by the oxygen vacancy; the other EPR signal peaks generated after the phosphor is irradiated by 254nm ultraviolet light can be attributed to the hyperfine coupling splitting caused by the single electron spin distribution on the germanium atom.

[0039] Embodiment 2:

[0040] A method for regulating the reversible body color of the photochromic hybrid phosphor material prepared in Example 1 comprises the steps of:

[0041] Zn 1.97 Na 0.03 GeO 4 Phosphor and NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The photochromic mixed phosphor material was prepared by physically mixing the phosphors in a mass ratio of 1:1, with an intensity of 6W / cm 2 The photochromic hybrid phosphor material was irradiated with 254 nm light for 1 min to color it. The color of the photochromic hybrid phosphor material gradually changed from white to purple. Then the colored photochromic hybrid phosphor material was irradiated with 254 nm light for 1 min to color it. 2, irradiated with near-infrared light with a wavelength of 980nm for 1s, its body color returns from purple to white. The process effect diagram of the photochromic hybrid phosphor material from body color to color change and then to body color recovery is shown in the figure Figure 5 As shown;

[0042] Na + Doped Zn 2 GeO 4 Photochromic phosphor materials and NaYb 0.5 Sm 0.5 (MoO 4 ) 2 The effect of the photochromic mixed phosphor material obtained by mixing the thermal radiation phosphor is shown in the figure below. Figure 5 (a) shows that its body color is white; the effect of the mixed phosphor material after irradiation with 254nm ultraviolet light for 1 minute is shown in Figure 5 As shown in (b), its body color changes from white to purple; Figure 5 (c) The hybrid phosphor material has achieved photochromic properties at 980nm laser with 47.39W / cm 2 The effect picture after irradiation with a power density of 1s. The irradiated part appears white, while the other unirradiated parts remain purple.

[0043] The photochromic mixed fluorescent powder material provided by the present invention can change the body color from white to purple by irradiating the mixed powder with 254nm ultraviolet light for 1 minute; it can recover from purple to white within 1 second, realize the rapid fading of the body color of the colored photochromic fluorescent powder, complete the reversible transformation, and has good reversibility and stability, so that the photochromic fluorescent powder is more convenient in practical applications; the photochromic mixed fluorescent powder material of the present invention uses ultraviolet light and near-infrared light as excitation sources to realize the reversible transformation of body color, does not need to rely on visible light for restoration, gets rid of the dependence of traditional visible light restoration on specific visible light wavelengths, thereby overcoming the limitations of visible light restoration, improving the reliability and stability of anti-counterfeiting effects, and broadening the scope of application; the photochromic mixed fluorescent powder material does not need heat treatment for body color restoration, and can avoid the adverse effects of traditional heat treatment methods. At the same time, the phosphor in the present technical solution is prepared by a high-temperature solid-phase method, and the preparation method is relatively simpler. The weighing accuracy is ensured in the raw material weighing stage, and then the raw materials are mixed evenly. Finally, the calcination temperature and time are controlled to prepare a large amount of mixed phosphor material. This simple preparation method is conducive to the large-scale production of the mixed phosphor, and is also conducive to promoting the practical application of the photochromic mixed phosphor material in the body color reversible control technology.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photochromic mixed phosphor material, characterized in that: The photochromic mixed phosphor material is Na + Doped Zn2GeO4 photochromic phosphor and Sm 3+ Doped NaYb(MoO4)2 thermal radiation phosphor; The Na + The chemical formula of doped Zn2GeO4 photochromic phosphor is: Zn 1.97 Na 0.03 GeO4; The Sm 3+ The chemical formula of NaYb(MoO4)2 doped thermal radiation phosphor is: NaYb 0.5 Sm 0.5 (MoO4)2 phosphor.

2. A method for reversibly controlling the body color of the photochromic hybrid phosphor material according to claim 1, characterized in that: The steps include: 1.97 Na 0.03 GeO4 phosphor and NaYb 0.5 Sm 0.5 The mixed phosphor material prepared by physically mixing (MoO4)2 phosphor in a mass ratio of 1:1 was colored by irradiation with 254 nm, and the body color of the material gradually changed from white to purple. The body color of the colored mixed material could be restored from purple to white under 980 nm near-infrared light irradiation.

3. The method for reversibly regulating body color according to claim 2, characterized in that: The 254 nm irradiation time was 1 min and the intensity was 6 W / cm 2 .

4. The method for reversibly regulating body color according to claim 2, characterized in that: The 980 nm near-infrared light irradiation time is 1 second, and the intensity is 47.39 W / cm 2 .

5. The method for reversibly regulating body color according to claim 2, characterized in that: The Zn 1.97 Na 0.03 The preparation method of GeO4 phosphor is as follows: ZnO and GeO2 were used as matrix materials, and Na2CO3 was used as doping material. ZnO, Na2CO3, and GeO2 were weighed according to the molar ratio of Zn, Na, and Ge of 1.97:0.03:1, respectively. After grinding and mixing, the mixed material was calcined at high temperature for 8 hours to obtain Zn. 1.97 Na 0.03 GeO4 phosphor.

6. The method for reversibly regulating body color according to claim 2, characterized in that: The NaYb 0.5 Sm 0.5 The preparation method of (MoO4)2 phosphor is as follows: According to the molar ratio of Na, Yb, Sm, and Mo of 1:0.5:0.5:2, Na2CO3, Yb2O3, Sm2O3, and MoO3 were weighed respectively, ground and mixed, and the mixture was calcined at high temperature for 6 hours to obtain NaYb 0.5 Sm 0.5 (MoO4)2 thermal radiation phosphor.

7. The method for reversibly regulating body color according to claim 5, characterized in that: The purity of the ZnO is 99.99%, the purity of GeO2 is 99.99%, and the purity of Na2CO3 is 99.8%.

8. The method for reversibly regulating body color according to claim 6, characterized in that: The purity of Na2CO3 is 99.8%, the purity of Yb2O3 is 99.99%, the purity of Sm2O3 is 99.99%, and the purity of MoO3 is 99.5%.

9. The method for reversibly regulating body color according to claim 5, characterized in that: The specific method of high temperature calcination is: placing the mixed material in an alumina crucible and placing it in a muffle furnace, and calcining it at 1150° C. for 8 hours in an air atmosphere.

10. The method for reversibly regulating body color according to claim 6, characterized in that: The specific method of high temperature calcination is: placing the mixed material in an alumina crucible and placing it in a muffle furnace, and calcining it at 900° C. for 6 hours in an air atmosphere.

11. Application of the photochromic mixed phosphor material according to claim 1 in anti-counterfeiting.

Images