An inorganic photochromic material, its preparation method and application

Abstract

This invention relates to the field of inorganic photochromic materials, specifically to an inorganic photochromic material, its preparation method, and its applications. Compared with existing technologies, the preparation method provided by this invention uses potassium carbonate, bismuth oxide, and titanium dioxide in a molar ratio of potassium, bismuth, and titanium of 1:3:4-x as raw materials, where 0≤x≤1, and calcines at a high temperature of 900℃~1000℃ to prepare an inorganic photochromic material with good photochromic properties and reversibility. The preparation method of this invention is simple, the raw materials are readily available, and the preparation cost is low. Furthermore, the irradiation light source required for the prepared inorganic photochromic material is a common 365nm ultraviolet light source, resulting in low application cost. Therefore, it solves the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications. Experimental results show that the inorganic photochromic material prepared by the method of this invention can be successfully used to prepare anti-counterfeiting and encryption materials.

Description

Technical Field

[0001] This invention relates to the field of inorganic photochromic materials, specifically to an inorganic photochromic material, its preparation method, and its application. Background Technology

[0002] Inorganic photochromic materials are a class of materials that change color when excited by a light source. Specifically, under irradiation with light of a specific wavelength, color centers are formed in inorganic photochromic materials. These color centers cause the materials to selectively absorb visible light, resulting in a visible color change. Furthermore, they can be bleached back to their original state by thermal or light stimulation. Utilizing this property, inorganic photochromic materials can be applied in fields such as anti-counterfeiting encryption, information storage, and optical switches.

[0003] Some shortcomings of common inorganic photochromic materials limit their large-scale industrial applications in fields such as anti-counterfeiting encryption, information storage, and optical switches. For example, while titanium dioxide photochromic materials can produce significant color changes after irradiation and exhibit good photochromic properties, their photochromic reversibility is poor. Ferroelectric oxides such as Na... 0.5 Bi 2.5 Nb₂O₉:Er photochromic materials, while exhibiting good reversibility of photochromism, show only subtle color changes. Germanate and tungstate photochromic materials, on the other hand, require readily available and expensive raw materials, resulting in high production costs. Bi 7-x Er x Ti4NbO 21 The ceramics require a 405nm blue-violet laser as an irradiation source, making their application cost high. These factors prevent existing inorganic photochromic materials from being suitable for large-scale industrial applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an inorganic photochromic material, its preparation method and application, thereby solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing inorganic photochromic materials, comprising the following steps:

[0007] Using potassium carbonate, bismuth, and titanium in a molar ratio of 1:3:4-x, potassium carbonate, bismuth oxide, and titanium dioxide as raw materials, the raw materials are wet-milled, mixed, and dispersed evenly. After drying and milling, a precursor is obtained. The precursor is then subjected to high-temperature calcination and milling to obtain an inorganic photochromic material. Wherein, 0 ≤ x ≤ 1, the calcination temperature is 900℃~1000℃, and the general chemical formula of the inorganic photochromic material is KBi3Ti. 4-x O 13-2x .

[0008] Compared with existing technologies, the preparation method provided by this invention uses potassium carbonate, bismuth oxide, and titanium dioxide in a molar ratio of potassium, bismuth, and titanium of 1:3:4-x (0≤x≤1) as raw materials, and subjectes the materials to high-temperature calcination at 900℃~1000℃. This process creates numerous oxygen vacancy defects in the prepared inorganic photochromic material. Irradiation with 365nm ultraviolet light causes these oxygen vacancies to capture photogenerated electrons and convert them into single-ionized oxygen vacancies, forming F-type color centers. This results in the inorganic photochromic material exhibiting excellent photochromic properties and reversibility. The preparation method of this invention is simple, uses readily available raw materials, and has low preparation costs. The 365nm ultraviolet light source required for the inorganic photochromic material prepared by this invention is readily available, eliminating the need for high-power lasers or xenon lamps as irradiation sources, thus reducing application costs and facilitating application. Therefore, the preparation method provided by the present invention is suitable for large-scale industrial applications to obtain inorganic photochromic materials with good photochromic properties and photochromic reversibility, thus solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0009] Optionally, the grinding time for the grinding process is 0.5h to 1h.

[0010] Optionally, the alcohol solvent is ethanol.

[0011] Optionally, the heating rate of the high-temperature calcination treatment is 3℃ / min to 5℃ / min.

[0012] Optionally, the drying temperature is 80℃~100℃.

[0013] Optionally, the wet milling process includes the following steps: using an alcohol solvent as the milling medium, mixing and milling the raw material with the alcohol solvent.

[0014] Optionally, the alcohol solvent is ethanol.

[0015] This invention also provides an inorganic photochromic material prepared by the above-mentioned method, wherein the general chemical formula of the inorganic photochromic material is KBi3Ti. 4-x O 13-2x , where 0≤x≤1.

[0016] Optionally, the inorganic photochromic material exhibits a color-developing effect under 365nm ultraviolet irradiation.

[0017] The present invention also provides an application of the above-mentioned inorganic photochromic material in the preparation of anti-counterfeiting and encryption materials.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The preparation method provided by this invention uses potassium carbonate, bismuth oxide, and titanium dioxide in a molar ratio of potassium, bismuth, and titanium of 1:3:4-x, where 0≤x≤1, and involves high-temperature calcination at 900℃~1000℃. This process creates numerous oxygen vacancy defects in the prepared inorganic photochromic material. Irradiation with 365nm ultraviolet light causes these oxygen vacancies to capture photogenerated electrons and convert them into single-ionized oxygen vacancies, forming F-type color centers. This results in the inorganic photochromic material exhibiting excellent photochromic properties and reversibility. The preparation method of this invention is simple, uses readily available raw materials, and has low preparation costs. The 365nm ultraviolet light source required for the inorganic photochromic material prepared by this invention is readily available, eliminating the need for high-power lasers or xenon lamps as irradiation sources, thus reducing application costs and facilitating application. Therefore, the preparation method provided by the present invention is suitable for large-scale industrial applications to obtain inorganic photochromic materials with good photochromic properties and photochromic reversibility, and solves the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0020] 2. Experimental results show that the color change of the inorganic photochromic material before and after photochromism is significant, with a large difference in light absorption rate. After being subjected to alternating ultraviolet irradiation and thermal stimulation five times, the photochromic performance of the inorganic photochromic material did not decrease significantly, indicating that the inorganic photochromic material prepared by the method of this invention has good photochromic performance and reversibility, and can be successfully used to prepare anti-counterfeiting and encryption materials. Moreover, photochromism can be achieved using a 365nm portable ultraviolet lamp, eliminating the need for high-power lasers or xenon lamps as irradiation sources, further saving costs and facilitating application. Attached Figure Description

[0021] Figure 1 The X-ray diffraction pattern of the inorganic photochromic material prepared in Example 1 of this invention.

[0022] Figure 2 The image shows the X-ray photoelectron spectrum of the inorganic photochromic material prepared in Example 2 of this invention.

[0023] Figure 3The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 1 of this invention before and after 15 minutes of 365nm ultraviolet radiation.

[0024] Figure 4 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 2 of this invention before and after 15 minutes of 365nm ultraviolet radiation.

[0025] Figure 5 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 3 of this invention before and after 15 minutes of 365nm ultraviolet radiation.

[0026] Figure 6 The images show the absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Comparative Example 1 of this invention before and after 15 minutes of exposure to 365nm ultraviolet radiation.

[0027] Figure 7 The images show the absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Comparative Example 2 of this invention before and after 15 minutes of 365nm ultraviolet radiation.

[0028] Figure 8 This is a graph showing the change in absorption rate of the inorganic photochromic material prepared in Example 3 of the present invention during the photochromic reversibility test. Detailed Implementation

[0029] To address the aforementioned technical problems, this invention provides an inorganic photochromic material, its preparation method, and its applications. The technical solution and embodiments of this invention will now be described in detail with reference to the accompanying drawings.

[0030] The technical solution adopted in this invention is as follows:

[0031] The inorganic photochromic materials and their preparation methods according to embodiments of the present invention will be described in detail below.

[0032] An embodiment of the present invention provides a method for preparing an inorganic photochromic material, comprising:

[0033] According to the molar ratio of potassium, bismuth, and titanium of 1:3:4-x, potassium carbonate, bismuth oxide, and titanium dioxide are used as raw materials, placed in a mortar, ethanol is added and ground and mixed for 0.5h to 1h, dried in an oven at 80℃ to 100℃, removed from the mortar and ground for another 0.5h to 1h, the mixture is placed in a crucible and calcined in a high-temperature furnace for 3h to 5h, cooled to room temperature, and the calcined product is ground for 0.5h to 1h to obtain an inorganic photochromic material.

[0034] Where 0 ≤ x ≤ 1, the calcination temperature for high-temperature calcination treatment is 900℃~1000℃, and the general chemical formula of the inorganic photochromic material is KBi3Ti. 4-xO 13-2x .

[0035] It should be noted that calcination at 900℃~1000℃ is to obtain KBi3Ti 4-x O 13-2x This ensures that the inorganic photochromic material contains a large number of oxygen vacancy defects. After irradiation with 365nm ultraviolet light, the oxygen vacancies capture photogenerated electrons and are converted into single-ionized oxygen vacancies, forming F-type color centers. This greatly improves the selective absorption of visible light, thus exhibiting obvious macroscopic color changes.

[0036] The heating rate for high-temperature calcination is 3℃ / min to 5℃ / min.

[0037] It should be noted that the grinding medium mentioned above is ethanol. Ethanol, as a wet grinding medium, can ensure that potassium carbonate, bismuth oxide and titanium dioxide are fully and evenly mixed.

[0038] In summary, the inorganic photochromic materials prepared by the above methods are in powder form. The preparation process is safe, can be carried out directly in air without the need for inert or reducing gas protection, has a low synthesis temperature, and is easy to operate. The resulting inorganic photochromic materials exhibit excellent photochromic properties, enabling diverse applications such as anti-counterfeiting encryption, information storage, and optical switches.

[0039] Embodiments of the present invention also provide an inorganic photochromic material with the chemical formula KBi3Ti. 4-x O 13-2x Where 0 ≤ x ≤ 1. This inorganic photochromic material is prepared by the above-described method for preparing inorganic photochromic materials.

[0040] Inorganic photochromic materials can produce photochromic phenomena when irradiated under a 365nm portable ultraviolet lamp. The samples before and after photochromic changes show obvious color changes, from light yellow to dark gray. The samples before and after photochromic changes have a large difference in light absorption rate, which can be applied to the production of anti-counterfeiting and encryption materials.

[0041] Inorganic photochromic materials have a large number of oxygen vacancy defects. After being irradiated with 365nm ultraviolet light, the oxygen vacancy traps photogenerated electrons and is converted into single ionized oxygen vacancy, forming F-type color centers. This greatly improves the selective absorption of visible light, thus exhibiting obvious macroscopic color changes.

[0042] The inorganic photochromic material showed no significant decrease in photochromic performance after being subjected to five alternating exposures to ultraviolet light and heat stimulation, indicating that the inorganic photochromic material has good reversibility, thermal stability and fatigue resistance, and can be applied in the field of anti-counterfeiting and encryption.

[0043] The present invention will now be described in detail through specific embodiments. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] Example 1

[0045] This embodiment provides a method for preparing an inorganic photochromic material. It includes:

[0046] Weigh 0.6911g of potassium carbonate, 6.9894g of bismuth oxide and 2.3961g of titanium dioxide and place them in a mortar. Add ethanol and grind and mix for 1 hour. Place the mixture in an oven and dry at 80°C. Remove the mortar and continue grinding for 0.5 hours.

[0047] The uniformly mixed raw materials were placed in a crucible and calcined in a high-temperature furnace at 950°C for 3 hours with a heating rate of 3°C / min. After cooling to room temperature, the calcined product was ground for 0.5 hours to obtain an inorganic photochromic material.

[0048] Example 2

[0049] This embodiment provides a method for preparing an inorganic photochromic material. It includes:

[0050] Weigh 0.6911g of potassium carbonate, 6.9894g of bismuth oxide and 3.1948g of titanium dioxide and place them in a mortar. Add ethanol and grind and mix for 0.5h. Place in an oven and dry at 90℃. Remove the mortar and continue grinding for 1h.

[0051] The uniformly mixed raw materials were placed in a crucible and calcined in a high-temperature furnace at 900°C for 5 hours with a heating rate of 4°C / min. After cooling to room temperature, the calcined product was ground for 1 hour to obtain an inorganic photochromic material.

[0052] Example 3

[0053] This embodiment provides a method for preparing an inorganic photochromic material. It includes:

[0054] Weigh 0.6911g of potassium carbonate, 6.9894g of bismuth oxide and 2.7955g of titanium dioxide and place them in a mortar. Add ethanol and grind and mix for 1 hour. Place the mixture in an oven at 100°C to dry. Remove the mortar and continue grinding for 1 hour.

[0055] The uniformly mixed raw materials were placed in a crucible and calcined in a high-temperature furnace at 1000℃ for 4 hours with a heating rate of 5℃ / min. After cooling to room temperature, the calcined product was ground for 1 hour to obtain an inorganic photochromic material.

[0056] Comparative Example 1

[0057] This embodiment provides a method for preparing an inorganic photochromic material. It includes:

[0058] Weigh 0.6911g of potassium carbonate, 6.9894g of bismuth oxide and 2.3961g of titanium dioxide and place them in a mortar. Add ethanol and grind and mix for 1 hour. Place the mixture in an oven and dry at 80°C. Remove the mortar and continue grinding for 0.5 hours.

[0059] The uniformly mixed raw materials were placed in a crucible and calcined in a high-temperature furnace at 850°C for 3 hours with a heating rate of 3°C / min. After cooling to room temperature, the calcined product was ground for 0.5 hours to obtain an inorganic photochromic material.

[0060] Comparative Example 2

[0061] This embodiment provides a method for preparing an inorganic photochromic material. It includes:

[0062] Weigh 0.6911g of potassium carbonate, 6.9894g of bismuth oxide and 2.3961g of titanium dioxide and place them in a mortar. Add ethanol and grind and mix for 1 hour. Place the mixture in an oven and dry at 80°C. Remove the mortar and continue grinding for 0.5 hours.

[0063] The uniformly mixed raw materials were placed in a crucible and calcined in a high-temperature furnace at 1050℃ for 3 hours with a heating rate of 3℃ / min. After cooling to room temperature, the calcined product was ground for 0.5 hours to obtain an inorganic photochromic material.

[0064] Test 1: Microstructure analysis.

[0065] The phase composition of the inorganic photochromic material 1 prepared in Example 1 was analyzed using an X'Pert3 Powder X-ray diffractometer, and the results are as follows: Figure 1 As shown. Figure 1 The X-ray diffraction pattern is shown for the inorganic photochromic material prepared in Example 1 of this invention. Figure 1 As can be seen, the diffraction peaks are sharp, indicating good crystallization effect. The main crystalline phase is potassium bismuth titanate, and the content of other impurity phases is low. This shows that the preparation method of the present invention can successfully prepare inorganic photochromic materials.

[0066] The elemental composition of inorganic photochromic material 2 was determined using an ESCALAB 250Xi X-ray photoelectron spectroscopy system. The results are shown below. Figure 2 . Figure 2 This is the X-ray photoelectron spectroscopy spectrum of the inorganic photochromic material prepared in Example 2 of the present invention. From... Figure 2 As can be seen, the photoelectron spectral peaks corresponding to K 2p, O 1s, Bi 4f and Ti 2p indicate that the sample contains K, O, Ti and Bi elements, but no other impurity elements, further demonstrating that the preparation method of the present invention can successfully prepare inorganic photochromic materials.

[0067] Test 2: Photochromic performance test.

[0068] Test materials: Inorganic photochromic materials prepared in Examples 1 to 3, and inorganic photochromic materials prepared in Comparative Examples 1 and 2.

[0069] Test equipment: UV3600Plus UV-Vis spectrophotometer, 8W 365nm portable UV lamp, and metal plate with a hollowed-out heart pattern.

[0070] Test method: Appropriate amounts of the inorganic photochromic materials prepared in different embodiments were taken, and their absorption spectra were first measured using a UV-Vis spectrophotometer. After irradiating the inorganic photochromic materials with a portable UV lamp for 15 minutes, the absorption spectra were measured again using a UV-Vis spectrophotometer. The test wavelength range of the UV-Vis spectrophotometer was 200 nm to 800 nm.

[0071] Take appropriate amounts of the inorganic photochromic materials prepared in different embodiments and completely fill the mold. Cover the sample with a metal plate with a hollowed-out heart pattern, irradiate it with a 365nm portable ultraviolet lamp for 15 minutes, remove the metal plate and take a picture of the inorganic photochromic material.

[0072] Analysis of test results: The test results of the photochromic properties of the inorganic photochromic materials prepared in Examples 1 to 3 are as follows: Figures 3-5 The photochromic performance test results of the inorganic photochromic materials prepared in Comparative Example 1 and Comparative Example 2 are shown in [reference]. Figure 6 and Figure 7 .

[0073] from Figures 3-5 It can be seen that, compared with before ultraviolet irradiation, after 15 minutes of irradiation with 365nm ultraviolet light, the absorption of light by the inorganic photochromic materials prepared in Examples 1 to 3 was significantly enhanced in the visible light range. After 15 minutes of irradiation with 365nm ultraviolet light, obvious heart-shaped patterns appeared on the surface of the inorganic photochromic materials prepared in Examples 1 to 3, indicating that the test samples underwent obvious photochromic phenomena. Among them, the area covered by the mold was lighter in color, being light yellow; the area forming the heart-shaped pattern was darker in color, being dark gray, indicating that the color of the sample changed from light yellow to dark gray after ultraviolet irradiation, and the color change was significant, further demonstrating that the inorganic photochromic materials before and after photochromic changes have a large difference in light absorption rate.

[0074] And from Figure 6 and Figure 7 It can be seen that the inorganic photochromic materials prepared in Comparative Example 1 and Comparative Example 2 also exhibited photochromic phenomena, but the color change of the samples after ultraviolet irradiation was not significant, and the difference in light absorption rate before and after photochromic changes was also small, indicating that the photochromic changes were not obvious.

[0075] Therefore, compared with the inorganic photochromic materials prepared in Examples 1 to 3, the inorganic photochromic materials prepared in Comparative Examples 1 and 2 have poorer photochromic properties, indicating that the calcination temperature during high-temperature calcination has a significant impact on the photochromic properties of inorganic photochromic materials. When the calcination temperature during high-temperature calcination is between 900°C and 1000°C, the prepared inorganic photochromic materials exhibit superior photochromic properties.

[0076] Test 3: Photochromic reversibility test.

[0077] Test material: Inorganic photochromic material prepared in Example 3.

[0078] Test equipment: UV3600Plus UV-Vis spectrophotometer, 8W 365nm portable UV lamp, far-infrared microcrystalline heating plate.

[0079] Test method: First, the original absorption spectrum of the inorganic photochromic material prepared in Example 3 was tested and recorded using a UV3600Plus UV-Vis spectrophotometer, and the absorption rate of the inorganic photochromic material at 500nm was recorded.

[0080] Thermal bleaching treatment: The inorganic photochromic material was irradiated with an 8W 365nm portable UV lamp for 15 minutes to induce photochromism. The absorption spectrum of the photochromic material was then measured and recorded using a UV-Vis spectrophotometer, and the absorbance at 500nm was also recorded. The photochromic material was then thermally stimulated at 350℃ using a far-infrared microcrystalline heating plate. After cooling to room temperature, the absorption spectrum was measured and recorded again using a UV-Vis spectrophotometer, and the absorbance at 500nm was recorded. This thermal bleaching treatment was repeated five times on the same inorganic photochromic material prepared in Example 3.

[0081] Test Result Analysis:

[0082] Figure 8 This is a graph showing the change in absorption rate of the inorganic photochromic material prepared in Example 3 of the present invention during the photochromic reversibility test.

[0083] from Figure 8It can be seen that during five cycles of thermal bleaching, the relative absorbance of the inorganic photochromic material prepared in Example 3 of this invention did not change significantly after each photochromic change or thermal stimulation. This indicates that the photochromic properties of the inorganic photochromic material prepared in Example 3 of this invention have good reversibility, and the inorganic photochromic material also possesses thermal stability and fatigue resistance, allowing for repeated use of the inorganic photochromic material prepared in Example 3 of this invention through thermal bleaching. Furthermore, this demonstrates that the inorganic photochromic material prepared by the method of this invention possesses good photochromic reversibility and can be applied in fields such as anti-counterfeiting encryption, information storage, and optical switches.

[0084] In summary, the inorganic photochromic material prepared by the method provided in this invention exhibits photochromic properties under irradiation with a 365nm portable ultraviolet lamp. The inorganic photochromic material shows a significant macroscopic color change before and after photochromic transformation, shifting from light yellow to dark gray. Furthermore, the inorganic photochromic material exhibits a large difference in light absorption rate before and after photochromic transformation. Moreover, the inorganic photochromic material prepared by the method of this invention possesses good photochromic reversibility, demonstrating that the inorganic photochromic material prepared by the method of this invention has excellent photochromic performance and reversibility, and can be successfully used to prepare anti-counterfeiting and encryption materials.

[0085] Furthermore, the preparation method of this invention is simple in steps and uses readily available raw materials, resulting in low preparation costs. The inorganic photochromic material prepared by this invention does not require a high-power laser or xenon lamp as an irradiation source, thus having low application costs and ease of application. Therefore, the preparation method provided by this invention is suitable for large-scale industrial applications to obtain inorganic photochromic materials with excellent photochromic properties and reversibility, solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0086] The above description is merely a preferred embodiment of the present invention, and the specific embodiments described above are not intended to limit the present invention. Various modifications and variations can be made within the scope of the technical concept of the present invention. All refinements, modifications, or equivalent substitutions made by those skilled in the art based on the above description are within the scope of protection of the present invention.

Claims

1. An inorganic photochromic material, characterized by, The chemical general formula of the inorganic photochromic material is KBi3Ti 4- x O 13-2x wherein x = 0.5; The inorganic photochromic material is prepared by the following steps: According to the molar ratio of potassium, bismuth and titanium being 1:3:3.5, the raw materials of potassium carbonate, bismuth oxide and titanium dioxide are uniformly dispersed by wet grinding, and then the precursor is prepared after drying and grinding; The inorganic photochromic material is prepared by grinding the precursor after high-temperature calcination treatment; The calcination temperature of the high-temperature calcination treatment is 900-1000℃, and the heating rate of the high-temperature calcination treatment is 3-5℃ / min.

2. The inorganic photochromic material according to claim 1, characterized in that, The grinding time of the grinding treatment is 0.5-1h.

3. The inorganic photochromic material of claim 1, wherein The temperature of the drying is 80-100℃.

4. The inorganic photochromic material of claim 1, wherein The wet grinding comprises the following steps: The raw materials are mixed and ground with the alcohol solvent as the grinding medium.

5. The inorganic photochromic material according to claim 4, wherein The alcohol solvent is ethanol.

6. The inorganic photochromic material of claim 1, wherein The inorganic photochromic material has color development effect under 365nm ultraviolet light irradiation.

7. Use of the inorganic photochromic material of claim 1 in the preparation of anti-counterfeiting encryption materials.

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