Photochromic ceramic powder, and preparation method and application thereof

Abstract

This invention relates to the field of photochromic ceramic powder technology, specifically to a photochromic ceramic powder, its preparation method, and its application. Ammonia dihydrogen phosphate, lithium carbonate, and titanium dioxide are weighed according to a stoichiometric ratio, and a certain amount of tungsten trioxide and cobalt oxide are weighed as dopants and mixed in a mortar. Alcohol is used as a mixing agent, and the mixture is ground until dry in the mortar to obtain the desired sample. The sample is placed in a box furnace and sintered using a high-temperature solid-state method. The pre-sintering temperature is 240℃, and the holding time is 3 hours, followed by sintering at 1000℃ for 260 minutes, and then in air for 4 hours. After the box furnace cools naturally to room temperature, the sample is removed and pulverized and ground in a ceramic mortar to finally obtain ceramic powder with reversible photochromic properties. The ceramic powder changes from light purple to brown under 365nm light irradiation and can return to its original state after holding at 600℃ for 5 hours; this provides a new matrix for the field of inorganic photochromic materials.

Description

Technical Field

[0001] This invention relates to the field of photochromic ceramic powder technology, specifically to a photochromic ceramic powder, its preparation method, and its application. Background Technology

[0002] Photochromic materials typically refer to compounds A that, when exposed to light of a certain wavelength, undergo a specific chemical reaction to produce product B, and then revert to their original form under light of another wavelength or thermal stimulation. According to current research, photochromic materials can be classified into organic and inorganic types. Inorganic photochromic materials exhibit significantly superior thermal stability, reversibility, and duration of color change compared to organic materials, thus attracting widespread attention from researchers. Inorganic photochromic materials encompass a wide variety of materials, including titanates, tungstates, molybdates, niobates, phosphates, etc., and possess potential applications in numerous fields such as optical anti-counterfeiting, optical information storage, and optical information encryption.

[0003] Current reports on inorganic photochromic phosphate materials mostly focus on halide-doped matrices, while reports on photochromic phosphate materials that are neither halide-free nor rare-earth-element-free are rare. Among them, NASICON-type fast ion conductor phosphate materials exhibit significant structural stability, ultra-high ionic conductivity, stable electrochemical performance, and thermodynamic properties. However, there are no reports on the application of NASICON-type fast ion conductor phosphate materials in the field of photochromism. Therefore, researching and expanding the application of novel matrix structure materials in the field of photochromism is of great significance.

[0004] Chinese patent document CN202310825197.1 discloses a photochromic phosphosilicate glass ceramic and its preparation method. Appropriate amounts of NH4H2PO4, SiO2, SrCO3, Al2O3, Cs2CO3, PbBr2, and KBr are weighed and mixed evenly. Appropriate amounts of AgBr and Cu2O are then added and ground to obtain a mixture. After melting and cooling, the resulting sample exhibits photochromic behavior under 365nm ultraviolet light. The corresponding color-changing area can be obtained according to the laser irradiation path, thus forming a clear pattern. Heating at 300℃ allows for rapid reversion back to the initial state before the color change. This color-changing and fading process can be stably repeated multiple times, showing promise in the field of optical storage. This invention also exhibits reversible photochromic behavior under 365nm ultraviolet light and heat treatment, and this behavior can be repeated multiple times. Furthermore, the sample of this invention is a powder that can be used to prepare flexible films, which can be bent or even folded at will, adapting to various application prospects such as anti-counterfeiting and information storage. It is convenient to use and simple to prepare. Existing patents, due to their inability to be folded or bent, limit their applications. Furthermore, they often contain harmful elements such as Pb, Ag, and Cu, posing risks to the environment and human health. This invention utilizes a simple high-temperature solid-state method to obtain the desired sample. It has significant application potential in anti-counterfeiting and information storage fields. It also provides a doping approach for the application of phosphate inorganic oxides in these fields. Compared to existing patents, it is more environmentally friendly and conducive to sustainable development. Summary of the Invention

[0005] The purpose of this invention is to provide a photochromic ceramic powder, its preparation method, and its application. This invention utilizes a high-temperature solid-state method to prepare a W... 6+ Co 2+ Ion-co-doped NASICON-type photochromic ceramic powder.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] A photochromic ceramic powder, wherein the photochromic ceramic powder is LiTi2(PO4)3 ceramic powder, comprising: NH4H2PO4, TiO2, and Li2CO3.

[0008] Furthermore, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, and 0.5 parts Li2CO3.

[0009] Furthermore, the raw material composition includes the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, and 0 to 0.11 parts WO3 doping.

[0010] Furthermore, the raw material composition includes the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, and also includes 0 to 0.11 parts WO3 doping and 0 to 0.11 parts CoO doping.

[0011] On the other hand, the present invention proposes a method for preparing the above-mentioned photochromic ceramic powder, comprising the following steps:

[0012] S1: Weigh the raw materials according to the following composition: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0-0.11 parts WO3 doping, and 0-0.11 parts CoO doping; mix the raw materials into an agate mortar, add alcohol and grind until evenly mixed and dry;

[0013] S2: Place the mixed raw materials from step S1 into a box furnace and pre-calcine at 240°C for 3 hours using the high-temperature solid-state method, then sinter at 1000°C for 260 minutes in air for 4 hours. After cooling to room temperature, remove the sample.

[0014] S3: Place the sample obtained in step S2 into a ceramic mortar and grind it thoroughly to obtain a fine powder.

[0015] Furthermore, in step S2, the pre-sintering temperature of the box furnace is 240℃, and the holding time is 3h, followed by a heating to 1000℃ for 260 minutes and a holding time of 4h.

[0016] On the other hand, the present invention proposes a film that changes color under ultraviolet light irradiation. The film is prepared from the above-mentioned photochromic ceramic powder. The preparation method includes: uniformly mixing the powder and colloid at a mass ratio of 1:2, and then drying them in an oven to obtain a flexible film; and inducing the film to change color and write patterns by ultraviolet laser light.

[0017] On the other hand, this invention proposes the application of the above-mentioned photochromic ceramic powder and preparation method in optical anti-counterfeiting.

[0018] The beneficial effects of this invention are:

[0019] Structural stability: NASICON-type fast ion conductor phosphate materials exhibit excellent structural stability, maintaining the integrity of their crystal structure under various environmental conditions. Therefore, using NASICON-type phosphates as the matrix material ensures the stability and long service life of photochromic ceramic powders.

[0020] Excellent optical properties: W co-doped in photochromic ceramic powder 6+ and Co 2+ Ions can absorb light of specific wavelengths and undergo chemical reactions, thereby changing color. 6+ and Co2+ Ions possess specific electronic energy level structures, and depending on the material's composition and doping concentration, diverse color changes can be achieved within the visible light range. Furthermore, the high optical transparency of photochromic ceramic powders gives them broader potential for applications.

[0021] Stability and Reversibility: The ion-hybrid structure of the photochromic ceramic powder exhibits excellent thermal stability and reproducible reversibility. When exposed to light of a specific wavelength, W... 6+ and Co 2+ Ions undergo charge transfer or chemical reactions within the crystal lattice, resulting in color changes. Under illumination with light of a different wavelength or under heat, these ions can return to their original positions, restoring the material to its original color. This stability and reversibility make photochromic ceramic powders promising for applications in optical anti-counterfeiting and optical information storage.

[0022] Advantages of the high-temperature solid-state method: The high-temperature solid-state method used in this invention for preparing photochromic ceramic powder has unique advantages. The high-temperature solid-state method can be carried out at higher temperatures, which is beneficial for the full reaction of raw materials and lattice rearrangement, thereby obtaining ceramic powder with good crystallinity and uniformity. Furthermore, the high-temperature solid-state method also features good controllability and a simple preparation process, making the preparation of photochromic ceramic powder more reliable and controllable.

[0023] The application potential of photochromic ceramic powder films: After photochromic ceramic powder is prepared into thin films, it can be applied in the field of optical anti-counterfeiting. These films can achieve color change and pattern writing through ultraviolet light irradiation, improving the anti-counterfeiting performance of products. The flexible nature of the film allows it to be applied to curved surfaces and bent objects, opening up a wider range of application scenarios.

[0024] In summary, the photochromic ceramic powder proposed in this invention has structural stability, excellent optical properties, stability and reversibility, and is prepared by a high-temperature solid-state method, and has the potential for application in fields such as optical anti-counterfeiting.

[0025] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a schematic diagram showing that the original sample of this invention did not change color under 356nm ultraviolet light irradiation;

[0028] Figure 2 A comparison image of the powder prepared in this invention before and after color change after being irradiated with a 365nm ultraviolet lamp for a certain period of time;

[0029] Figure 3 This is a schematic diagram of the thin film prepared according to the present invention;

[0030] Figure 4 This is a schematic diagram showing the optical information written into the thin film of the present invention after being irradiated by a 365nm ultraviolet lamp;

[0031] Figure 5 This is a comparison of the diffuse reflectance spectra of the sample before and after color change; the diffuse reflectance of the sample decreased significantly before and after color change. This indicates that the sample exhibited a significant color change under a 365nm ultraviolet lamp.

[0032] Figure 6 This is a schematic diagram of the sample of the present invention after it has been heated and faded.

[0033] Figure 7 This is an XRD pattern of the sample of the present invention; comparison with the standard PDF card of LiTi2(PO4)3 shows that the prepared sample is a pure phase and no impurities are generated. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] The photochromic ceramic powder described in this embodiment comprises raw materials in the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0 to 0.11 parts WO3 doping, and 0 to 0.11 parts CoO doping.

[0037] In this embodiment, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, and 0 to 0.11 parts WO3 doping.

[0038] In this embodiment, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, and 0 to 0.11 parts WO3 doping.

[0039] In this embodiment, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0 to 0.11 parts WO3 doping, and 0 to 0.11 parts CoO doping.

[0040] On the other hand, the present invention proposes a method for preparing the above-mentioned photochromic ceramic powder, comprising the following steps:

[0041] S1: Weigh the raw materials according to the following composition: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0-0.11 parts WO3 doping, and 0-0.11 parts CoO doping; mix the raw materials into an agate mortar, add alcohol and grind until evenly mixed and dry;

[0042] S2: Place the mixed raw materials from step S1 into a box furnace and sinter them in air at 1000°C for 4 hours using a high-temperature solid-state method. After the temperature has cooled to room temperature, take out the sample.

[0043] S3: Place the sample obtained in step S2 in a ceramic mortar and grind it thoroughly to obtain a fine powder.

[0044] In this embodiment, the pre-sintering temperature of the box furnace in step S2 is 240°C, and the holding time is 3 hours. Then, the temperature is increased to 1000°C, the heating time is 260 minutes, and the holding time is 4 hours.

[0045] On the other hand, the present invention proposes a film that changes color under ultraviolet light irradiation. The film is prepared from the above-mentioned photochromic ceramic powder. The preparation method includes: uniformly mixing the powder and colloid at a mass ratio of 1:2, and then drying them in an oven to obtain a flexible film; and inducing the film to change color and write patterns by ultraviolet laser light.

[0046] On the other hand, this invention proposes the application of the above-mentioned photochromic ceramic powder and preparation method in optical anti-counterfeiting.

[0047] Example 2

[0048] The photochromic ceramic powder described in this embodiment comprises raw materials in the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0 to 0.11 parts WO3 doping, and 0 to 0.11 parts CoO doping.

[0049] In this embodiment, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, and 0.5 parts Li2CO3.

[0050] The preparation method of the above-mentioned photochromic ceramic powder includes the following steps:

[0051] S1: Undoped with W 6+ Co 2+ To prepare the ion-modified ceramic powder, 3g each of NH4H2PO4, TiO2, and Li2CO3 were weighed according to the stoichiometric ratio, resulting in 3.8514g of NH4H2PO4, 1.7830g of TiO2, and 0.4124g of Li2CO3. The powder was then mixed with alcohol and ground in an agate mortar for 30 minutes to obtain a dry powder. The powder was placed in a box furnace and sintered using a high-temperature solid-state method. The pre-sintering temperature was 240℃, and the holding time was 3 hours. Subsequently, the powder was sintered in air at 1000℃ for 260 minutes to obtain the desired powder.

[0052] S2: When irradiated with a 5W ultraviolet lamp, the powder did not show any color change.

[0053] The ceramic powder prepared in Example 1 was photographed after being irradiated with ultraviolet light for a certain period of time, as shown in the image. Figure 1 As shown, the irradiated powder did not exhibit photochromism.

[0054] Example 3

[0055] The photochromic ceramic powder described in this embodiment comprises raw materials in the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0 to 0.11 parts WO3 doping, and 0 to 0.11 parts CoO doping.

[0056] In this embodiment, the raw materials are composed of the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, and 0 to 0.11 parts WO3 doping.

[0057] The preparation method of the above-mentioned photochromic ceramic powder includes the following steps:

[0058] S1: Design doping with W 6+ The ion ratio was determined by weighing 3g of NH4H2PO4, TiO2, and Li2CO3 by mass. 3.8514g of NH4H2PO4, 1.7830g of TiO2, 0.4124g of Li2CO3, and 0.0052g of WO3 (0.2% doping) were added to an agate mortar and ground with alcohol for 30 minutes to obtain a dry powder. The powder was then placed in a box furnace and pre-sintered using a high-temperature solid-state method at 240℃ for 3 hours, followed by sintering at 1000℃ for 260 minutes in air for 4 hours. The sample was then naturally cooled to room temperature to obtain the desired sample.

[0059] S2: Place the obtained sample in a ceramic mortar and grind it thoroughly to obtain a fine powder.

[0060] S3: When powder is irradiated with ultraviolet laser for a certain period of time, the powder will show a slight discoloration.

[0061] Example 4

[0062] The photochromic ceramic powder described in this embodiment comprises the following raw material composition in the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0-0.11 parts WO3 doping, and 0-0.11 parts CoO doping. In this embodiment, the raw material composition includes the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0-0.11 parts WO3 doping, and 0-0.11 parts CoO doping.

[0063] The preparation method of the above-mentioned photochromic ceramic powder includes the following steps:

[0064] S1: Design doping with W 6+ Co 2+ Ion ratio, by mass ratio: NH4H2PO4, TiO2, Li2CO3:WO3, CoO;

[0065] Weigh 3g into an agate mortar and grind with alcohol for 30 minutes to obtain a dry powder. Place the powder in a box furnace and pre-sinter it using a high-temperature solid-state method at a temperature of 240℃ for 3 hours. Then, sinter it in air at 1000℃ for 260 minutes for 4 hours. Allow it to cool naturally to room temperature to obtain the desired sample.

[0066] S2: Place the obtained sample in a ceramic mortar and grind it thoroughly to obtain a fine powder.

[0067] S3: Powder irradiated by ultraviolet light, such as Figure 2 As shown, the powder exhibits a significant color change after being irradiated for a certain period of time. The diffuse reflectance spectra of the powder before and after irradiation with 365nm light were measured using a spectrophotometer (U-4100) equipped with an integrating sphere. Figure 5 As shown;

[0068] S4: Mix the powder and colloid at a mass ratio of 1:2, then place them in an oven to dry, obtaining the following: Figure 3 The flexible film shown can be printed with various patterns using a pattern template to create patterned anti-counterfeiting labels, such as... Figure 4 As shown;

[0069] The powders prepared in Examples 2-4 of this invention were all pre-sintered at 240°C for 3 hours, followed by a heating at 1000°C for 260 minutes and a holding time of 4 hours.

[0070] By adjusting the dopant ions to control the photochromic effect and degree of color change in the sample, a halogen- and rare-earth-free photochromic phosphate material with a NASICON-type structure was prepared and its application in optical anti-counterfeiting was realized.

[0071] In summary, this invention has prepared a W 6+ Co 2+ Ion-co-doped NASICON-type photochromic ceramic powder was prepared by weighing ammonium dihydrogen phosphate, lithium carbonate, titanium dioxide, and tungsten trioxide according to stoichiometric ratios and mixing them in a mortar. Alcohol was used as a mixing agent, and the mixture was ground until dry in the mortar to obtain the desired sample. The sample was pure phase. Figure 1 As shown. The sample was placed in a box furnace and sintered using a high-temperature solid-state method. The conditions were: pre-sintering temperature of 240℃ for 3 hours, followed by a heating to 1000℃ for 260 minutes, and air sintering for 4 hours. After the box furnace cooled naturally to room temperature, the sample was removed and pulverized in a ceramic mortar to obtain ceramic powder with reversible photochromic properties. The ceramic powder changed from light purple to brown under 365nm light irradiation and recovered its original state after holding at 600℃ for 5 hours. Figure 6 As shown; the present invention LiTi2(PO4)3:W 5+ Co 3+ Photochromic materials exhibit highly distinctive photochromic effects under ultraviolet light irradiation, and the color-changing effect is reversible, providing a new matrix for the field of inorganic photochromic materials.

[0072] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A photochromic ceramic powder, characterized in that: It includes raw materials in the following proportions: 3 parts NH4H2PO4, 2 parts TiO2, and 0.5 parts Li2CO3; it also contains WO3, with a doping amount greater than 0 and less than or equal to 0.11 parts.

2. The photochromic ceramic powder as described in claim 1, characterized in that: It is also doped with CoO, with a doping amount greater than 0 and less than or equal to 0.11 parts.

3. The method for preparing photochromic ceramic powder as described in claim 1 or 2, characterized in that: Includes the following steps: S1: Weigh the raw materials according to the following composition: 3 parts NH4H2PO4, 2 parts TiO2, 0.5 parts Li2CO3, 0.11 parts WO3 doping, and 0.11 parts CoO doping; mix the raw materials into an agate mortar, add alcohol and grind until evenly mixed and dry; S2: Place the mixed raw materials from step S1 into a box furnace and pre-calcine at 240°C for 3 hours using the high-temperature solid-state method, and then sinter in air at 1000°C for 260 minutes for 4 hours. After cooling to room temperature, remove the sample. S3: Place the sample obtained in step S2 into a ceramic mortar and grind it thoroughly to obtain a fine powder.

4. The preparation method according to claim 3, characterized in that: In step S2, the preheating temperature of the box furnace is 240℃, and the holding time is 3h. Then, the temperature is increased to 1000℃, the heating time is 260 minutes, and the holding time is 4h.

5. The application of photochromic ceramic powder as described in claim 1 or 2 in optical anti-counterfeiting.

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