CN116443929B - High-entropy perovskite photochromic ceramic material and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of high-entropy perovskite ceramic materials, in particular to a high-entropy perovskite photochromic ceramic material and a preparation method thereof. The chemical general formula of the high-entropy perovskite photochromic ceramic material is ABO ₃, wherein the A-site element is Ba element, and the B-site element is composed of five elements of Zr element, mg element, nb element, ta element, sn element, ti element and Zn element according to the mol ratio of 1:1:1:1:1. The invention provides a method for preparing a high-entropy perovskite ceramic material with stable single-phase structure, which is characterized in that the method is used for purposefully designing the problems existing in the development of the existing high-entropy material, selecting ABO ₃ perovskite oxide with a relatively stable structure, carrying out high entropy on the B site by utilizing various transition metal elements, and successfully preparing the high-entropy perovskite ceramic material with stable single-phase structure, so that obvious photochromism can occur, and the method has an important promotion effect on the development of the high-entropy non-metal oxide material.

Description

A high entropy perovskite photochromic ceramic material and preparation method thereof

Technical Field

The present invention relates to the technical field of high entropy perovskite ceramic materials, and in particular to a high entropy perovskite photochromic ceramic material and a preparation method thereof.

Background Art

Generally, a mixture containing five or more elements in an equiatomic ratio or a nearly equiatomic ratio is defined as a high entropy material. Compared with traditional materials, high entropy materials have four unique effects, namely, the high entropy effect of thermodynamics, the lattice distortion effect, the sluggish effect of kinetics, and the "cocktail effect" in performance. Thanks to its unique four effects, high entropy materials show the advantages of huge component adjustment space and strong adjustability of material properties, which makes them have excellent performance and a relatively broad application prospect. In the past, most of the research on high entropy materials focused on high entropy alloys, and relatively few studies on high entropy ceramic materials, and most of them chose shale, fluorite, pyrochlore and spinel structures for high entropy. High entropy ceramics based on these structures are difficult to form single-phase materials, and most of them have obvious second phases or even third phases. Finding high entropy ceramics with a completely new structure is an urgent problem to be solved in the development of high entropy ceramics.

Summary of the invention

Based on the above content, the present invention provides a high entropy perovskite photochromic ceramic material and a preparation method thereof. The high entropy perovskite photochromic ceramic material of the present invention can exhibit obvious photochromic phenomenon and has a perovskite structure.

To achieve the above object, the present invention provides the following solutions:

One of the technical solutions of the present invention is a high entropy perovskite photochromic ceramic material, the general chemical formula of which is ABO ₃ , wherein the A-site element is Ba, and the B-site elements are composed of five elements of Zr, Mg, Nb, Ta, Sn, Ti and Zn in a molar ratio of 1:1:1:1:1.

The ionic radii of the above-mentioned B-site elements are not much different in the case of hexacoordination, which reduces the difference in ionic size and is conducive to the synthesis of a stable single-phase structure. However, the radii of elements such as Ca and Pb are too large, which can easily cause large lattice distortion and is not conducive to the formation of a stable single-phase structure.

The three elements Zr/Nb/Ta meet the B-site ion radius and valence requirements. The three elements Zr/Nb/Ta are resistant to high temperatures, not easily volatile, and can exist stably after high-temperature synthesis, supporting the formation of a stable single-phase structure.

Further, the chemical formula is: Ba(Zr _0.2 Mg _{0.2 Nb} 0.2 Ta _0.2 Sn _0.2 )O ₃ , Ba(Zr _0.2 Mg _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ , Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Sn _0.2 )O ₃ or Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ .

The second technical solution of the present invention is a method for preparing the above-mentioned high entropy perovskite photochromic ceramic material, comprising the following steps:

Step 1, mixing and ball-milling metal carbonates and/or metal oxides corresponding to the constituent elements of the high entropy perovskite photochromic ceramic material to obtain a mixed material;

Step 2, drying the mixed material to obtain high entropy perovskite ceramic powder;

Step 3: calcining the high entropy perovskite ceramic powder to obtain the high entropy perovskite photochromic ceramic material.

Furthermore, in step 1, the ball milling is specifically wet ball milling, and the grinding solvent is distilled water and/or anhydrous ethanol; the ball milling time is 12 to 48 hours.

Preferably, the grinding solvent is anhydrous ethanol. Anhydrous ethanol is non-toxic and harmless and has good volatility, which can improve the dispersibility of raw materials during ball milling and is more conducive to the mixing of raw materials.

Furthermore, in step 2, the drying treatment is carried out at a temperature of 50 to 150° C. and for a time of 18 to 36 hours.

Furthermore, in step 3, the calcination is a two-stage calcination, specifically: the first stage calcination is calcination at 1200-1300° C. for 3-9 hours; the second stage calcination is calcination at 1300-1450° C. for 3-9 hours.

The purpose of the first stage of calcination is to allow carbonate to expel carbon dioxide and moisture in the raw materials in a high temperature environment to prevent pores and cracks from appearing during the subsequent sintering process. Various raw materials are melted and mixed until a crystallized powder precursor is obtained.

The purpose of the second calcination is to empty the organic matter and increase the density, and to refine the grains under high temperature environment to obtain high-entropy perovskite photochromic ceramic materials with regular grain shape and size.

The heating and cooling rates of the above two stages of calcination are: heating at 4°C/min and cooling at 5°C/min.

If the calcination temperature is lower than the above range, the ceramic-forming effect is poor or even no ceramic-forming effect occurs, thus affecting the photochromic performance; if the temperature is higher than the above range, the sample will show greater brittleness and will cause bending of the sample, which will also affect the photochromic performance. Therefore, the present invention preferably limits the first stage calcination temperature to 1200-1300°C, and the second stage calcination temperature to 1300-1450°C.

If the heating rate is too high, the heating speed will be too fast and the various elements in the sample cannot be well integrated, which is not conducive to the synthesis of single-phase structure and the uniform distribution of various elements. If the heating rate is too low, the heating speed will be too slow and energy will be wasted.

If the cooling rate is too high, the various elements in the sample will be segregated and the sample will crack. If the cooling rate is too low, the cooling rate will be too slow, which will extend the sintering time and is not conducive to actual production synthesis. Therefore, the preferred temperature increase and temperature decrease rates of the two-stage calcination are: 4°C/min for temperature increase and 5°C/min for temperature decrease.

Furthermore, after the first stage of calcination is completed, the steps of grinding and pressing are also included.

The pressure of the pressing molding is 10-15 MPa, and the pressing is performed into a round sheet.

Furthermore, after the second stage of calcination is completed, the steps of polishing, grinding and ultrasonic cleaning are also included.

The purpose of polishing, grinding and ultrasonic cleaning is to facilitate subsequent testing, wherein the polishing, grinding and cleaning processes all adopt methods well known to those skilled in the art.

The third technical solution of the present invention is the application of the above-mentioned high entropy perovskite photochromic ceramic material in the fields of storage and anti-counterfeiting.

A fourth technical solution of the present invention is a photochromic anti-counterfeiting material, comprising the above-mentioned high entropy perovskite photochromic ceramic material.

The present invention discloses the following technical effects:

The structural stability of ABO ₃ type perovskite oxide is better than that of other structures. After high entropy treatment, the structure is not prone to collapse and can still maintain structural stability, which can ensure that the synthesized sample is a single-phase material. The present invention carries out targeted design for the problems existing in the current development of high entropy materials, selects ABO ₃ type perovskite oxide with relatively stable structure, uses a variety of transition metal elements and alkaline earth metal elements to carry out high entropy treatment of its B position, and successfully prepares a high entropy perovskite ceramic material with a stable single-phase structure, which has an important role in promoting the development of high entropy non-metallic oxide materials.

Due to the presence of more metal elements, high-entropy materials have larger lattice distortion inside the material, which is conducive to the generation of more defects inside the material. This feature is used to regulate the material composition and obtain a high-entropy perovskite ceramic material that can produce obvious photochromic phenomenon.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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.

FIG. 1 is an X-ray diffraction pattern of the high entropy perovskite photochromic ceramic material prepared in Examples 1 to 4 of the present invention.

Figure 2 is a scanning electron microscope (SEM) image of the high entropy perovskite photochromic ceramic material prepared in Examples 1 to 4 of the present invention; wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4.

FIG3 is an element distribution (EDS) diagram of the high entropy perovskite photochromic ceramic material prepared in Example 2 of the present invention.

Figure 4 shows photochromic photographs of the high entropy perovskite photochromic ceramic material prepared in Example 4 of the present invention; wherein, (a) is a photograph when no photochromic phenomenon occurs; (b) is a photograph of the sample after photochromic phenomenon occurs after irradiation with 365nm light for 0.5s; (c) is a photograph of the sample after photochromic phenomenon occurs after irradiation with 365nm light for 120s; (d) is a photograph comparing the time when no photochromic phenomenon occurs and the time when photochromic phenomenon occurs after irradiation with 365nm light for 120s.

Figure 5 is a spectrum of the surface reflectivity of the high entropy perovskite photochromic ceramic material prepared in Examples 1 to 4 of the present invention at room temperature, the surface reflectivity after being irradiated with a 365nm laser for 120s, and the surface reflectivity after being heated at 250°C for 60s; wherein (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4.

DETAILED DESCRIPTION

Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

The "room temperature" described in the present invention means 15-30°C unless otherwise specified.

Unless otherwise specified, the raw materials used in the embodiments of the present invention can be obtained through commercial channels.

The sources and purities of the raw materials used in the examples of the present invention are shown in Table 1.

Table 1

Raw material name Manufacturer purity BaCO ₃ Aladdin Reagents (Shanghai) Co., Ltd. 99% ZrO ₂ Aladdin Reagents (Shanghai) Co., Ltd. 99.99% MgO Sinopharm Chemical Reagent Co., Ltd. ≥99% _{Nb2O5 ​} Aladdin Reagents (Shanghai) Co., Ltd. 99.9% Ta ₂ O ₅ Aladdin Reagents (Shanghai) Co., Ltd. 99.99% _SnO2 Sinopharm Chemical Reagent Co., Ltd. ≥99.5% _TiO2 Aladdin Reagents (Shanghai) Co., Ltd. 99% ZnO Aladdin Reagents (Shanghai) Co., Ltd. 99%

Example 1

A high entropy perovskite photochromic ceramic material with a chemical formula of Ba(Zr _0.2 Mg _0.2 Nb _0.2 Ta _0.2 Sn _0.2 )O ₃ is prepared in the following steps:

Step 1, weigh raw materials BaCO ₃ , ZrO ₂ , MgO, Nb ₂ O 5 , Ta 2 O 5 , SnO ₂ according to the molar ratio of Ba, Zr, Mg, Nb, Ta and Sn of ₅ :1:1:1: ₁ : ₁ ; put them into a ball mill together with anhydrous ethanol and mill for 24 hours to obtain a mixed material.

Step 2: Transfer the mixture obtained in step 1 into an ordinary glass beaker using a straw, place it in an electric constant temperature forced air drying oven at 90° C. and dry it for 24 hours to obtain a high entropy perovskite ceramic powder.

Step 3, calcining the high entropy perovskite ceramic powder obtained in step 2 in two stages;

The first stage of calcination: the high entropy perovskite ceramic powder is placed in a corundum crucible and placed in a muffle furnace, and the temperature is increased from room temperature to 1300°C at a heating rate of 4°C/min for 6 hours, and then the temperature is reduced to room temperature at a cooling rate of 5°C/min to obtain a powder precursor; the powder precursor is placed in an agate mortar and ground until it becomes a fine powder without obvious particles, and then transferred to a tablet pressing mold, and a pressure of 10Mpa is applied to obtain a circular sheet with a regular shape and a smooth surface;

The second stage of calcination: the circular flake body is placed in a muffle furnace and heated from room temperature to 1400°C at a heating rate of 4°C/min for calcination for 6 hours, and then cooled to room temperature at a cooling rate of 5°C/min to obtain a circular flake high-entropy perovskite ceramic material; the surface is polished and ground with common polishing powder to obtain a circular ceramic sheet with a smooth surface; in order to remove the polishing powder and other impurities on the surface, ultrasonic cleaning is performed to obtain a high-entropy perovskite photochromic ceramic material with a smooth and clean surface and a chemical formula of Ba(Zr _0.2 Mg _0.2 Nb _0.2 Ta _0.2 Sn _0.2 )O ₃ .

Example 2

A high entropy perovskite photochromic ceramic material with a chemical formula of Ba(Zr _0.2 Mg _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ is prepared in the following steps:

Step 1, weigh raw materials BaCO ₃ , ZrO ₂ , MgO, Nb 2 O 5 , Ta 2 O 5 , and _{TiO 2 according} to a molar ratio of 5:1:1:1:1: ₁ among Ba, Zr, Mg, _Nb , _Ta and Ti; put them into a ball mill together with anhydrous ethanol and mill them for 24 hours to obtain a mixed material.

Step 2: Transfer the mixture obtained in step 1 into an ordinary glass beaker using a straw, place it in an electric constant temperature forced air drying oven at 90° C. and dry it for 24 hours to obtain a high entropy perovskite ceramic powder.

Step 3, calcining the high entropy perovskite ceramic powder obtained in step 2 in two stages;

The first stage of calcination: the high entropy perovskite ceramic powder is placed in a corundum crucible and placed in a muffle furnace. The temperature is increased from room temperature to 1300°C at a heating rate of 4°C/min for 6 hours, and then the temperature is reduced to room temperature at a cooling rate of 5°C/min to obtain a powder precursor; the powder precursor is placed in an agate mortar and ground until it becomes a fine powder without obvious particles, and then transferred to a tablet pressing mold. A pressure of 10Mpa is applied to obtain a circular sheet with a regular shape and a smooth surface;

The second stage of calcination: the circular flake body is placed in a muffle furnace and heated from room temperature to 1400°C at a heating rate of 4°C/min for calcination for 6 hours, and then cooled to room temperature at a cooling rate of 5°C/min to obtain a circular flake high-entropy perovskite ceramic material; the surface is polished and ground with common polishing powder to obtain a circular ceramic sheet with a smooth surface; in order to remove the polishing powder and other impurities on the surface, ultrasonic cleaning is performed to obtain a high-entropy perovskite photochromic ceramic material with a smooth and clean surface and a chemical formula of Ba(Zr _0.2 Mg _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ .

Example 3

A high entropy perovskite photochromic ceramic material with a chemical formula of Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Sn _0.2 )O ₃ is prepared in the following steps:

Step 1, weigh raw materials BaCO ₃ , ZrO ₂ , ZnO, Nb 2 O 5 , Ta 2 O 5 , SnO ₂ according to the molar ratio of Ba, Zr, Zn, Nb, Ta and Sn of ₅ :1:1:1:1: ₁ ; put them into a ball mill together with _anhydrous ethanol _and mill them for 24 hours to obtain a mixed material.

Step 2: Transfer the mixture obtained in step 1 into an ordinary glass beaker using a straw, place it in an electric constant temperature forced air drying oven at 90° C. and dry it for 24 hours to obtain a high entropy perovskite ceramic powder.

Step 3, calcining the high entropy perovskite ceramic powder obtained in step 2 in two stages;

The first stage of calcination: the high entropy perovskite ceramic powder is placed in a corundum crucible and placed in a muffle furnace. The temperature is increased from room temperature to 1300°C at a heating rate of 4°C/min for 6 hours, and then the temperature is reduced to room temperature at a cooling rate of 5°C/min to obtain a powder precursor; the powder precursor is placed in an agate mortar and ground until it becomes a fine powder without obvious particles, and then transferred to a tablet pressing mold. A pressure of 10Mpa is applied to obtain a circular sheet with a regular shape and a smooth surface;

The second stage of calcination: the circular flake body is placed in a muffle furnace and heated from room temperature to 1400°C at a heating rate of 4°C/min for calcination for 6 hours, and then cooled to room temperature at a cooling rate of 5°C/min to obtain a circular flake high-entropy perovskite ceramic material; the surface is polished and ground with common polishing powder to obtain a circular ceramic sheet with a smooth surface; in order to remove the polishing powder and other impurities on the surface, ultrasonic cleaning is performed to obtain a high-entropy perovskite photochromic ceramic material with a smooth and clean surface and a chemical formula of Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Sn _0.2 )O ₃ .

Example 4

A high entropy perovskite photochromic ceramic material with a chemical formula of Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ is prepared in the following steps:

Step 1, weigh raw materials BaCO ₃ , ZrO ₂ , ZnO, Nb 2 O 5 , Ta 2 O 5 , and TiO ₂ according to a molar ratio of Ba, Zr, Zn, Nb, Ta and Ti of ₅ :1:1:1:1: ₁ ; put them into a ball mill together with _anhydrous ethanol _and mill them for 24 hours to obtain a mixed material.

Step 2: Transfer the mixture obtained in step 1 into an ordinary glass beaker using a straw, place it in an electric constant temperature forced air drying oven at 90° C. and dry it for 24 hours to obtain a high entropy perovskite ceramic powder.

Step 3, calcining the high entropy perovskite ceramic powder obtained in step 2 in two stages;

The first stage of calcination: the high entropy perovskite ceramic powder is placed in a corundum crucible and placed in a muffle furnace. The temperature is increased from room temperature to 1300°C at a heating rate of 4°C/min for 6 hours, and then the temperature is reduced to room temperature at a cooling rate of 5°C/min to obtain a powder precursor; the powder precursor is placed in an agate mortar and ground until it becomes a fine powder without obvious particles, and then transferred to a tablet pressing mold. A pressure of 10Mpa is applied to obtain a circular sheet with a regular shape and a smooth surface;

The second stage of calcination: the circular flake body is placed in a muffle furnace and heated from room temperature to 1400°C at a heating rate of 4°C/min for calcination for 6 hours, and then cooled to room temperature at a cooling rate of 5°C/min to obtain a circular flake high-entropy perovskite ceramic material; the surface is polished and ground with common polishing powder to obtain a circular ceramic sheet with a smooth surface; in order to remove the polishing powder and other impurities on the surface, ultrasonic cleaning is performed to obtain a high-entropy perovskite photochromic ceramic material with a smooth and clean surface and a chemical formula of Ba(Zr _0.2 Zn _0.2 Nb _0.2 Ta _0.2 Ti _0.2 )O ₃ .

Performance Testing:

(I) X-ray diffraction experiment:

An X-ray diffraction experiment was performed on the high entropy perovskite photochromic ceramic materials (samples) prepared in Examples 1 to 4 to obtain XRD diffraction patterns corresponding to each example.

FIG1 is an X-ray diffraction spectrum of the high entropy perovskite photochromic ceramic material prepared in Examples 1 to 4 at a diffraction angle of 20 to 80°; the diffraction peaks of the four samples correspond well to the BaSnO ₃ (PDF15-0780) standard card, and there is no obvious second phase. The synthesized samples are pure phase substances, indicating that the samples have successfully achieved high entropy, indicating that the preparation of high entropy perovskite ceramic materials can be achieved based on the technical solution of the present invention, and a stable pure phase structure can be maintained. Through analysis, it is known that the four samples all belong to a stable cubic phase structure. It can be found from FIG1 that the positions of the diffraction peaks of the samples prepared in Examples 1 and 3 are shifted to the small angle direction compared with the samples prepared in Examples 2 and 4. This is because Sn ²⁺ (CN＝8, ) has a larger ionic radius than Ti ²⁺ (CN＝8, ).

(ii) Scanning electron microscopy experiment:

FIG. 2 is a scanning electron microscope (SEM) image of the high entropy perovskite photochromic ceramic material prepared in Examples 1 to 4. As shown in (a), (b), (c) and (d) in Figure 2, they are scanning electron microscope (SEM) images of high entropy perovskite photochromic ceramic materials (samples) prepared in Examples 1 to 4, respectively. The surfaces of the four samples are flat and smooth without obvious holes, and the grains are arranged regularly in sequence, showing a large density; the grains on the surface of the sample prepared by Example 1 and the sample prepared by Example 3 are large flat plates, and the grains on the surface of the sample prepared by Example 2 and the sample prepared by Example 4 are small spheres; through analysis, it is known that the grain surfaces of the samples prepared in Example 1 and the samples prepared in Example 3 have fine cracks, indicating that the brittleness of the samples is relatively large; and the grain size of the samples prepared in Example 1 and the samples prepared in Example 3 is relatively large. These two points are caused by the high sintering temperature. The high sintering temperature will promote the secondary crystallization of the grains, thereby increasing the crystal size, and at the same time will increase the brittleness of the ceramic and reduce the toughness of the ceramic, indicating that the Ti element is more resistant to high temperatures than the Sn element.

(III) Element distribution (EDS) experiment:

Figure 3 is an element distribution (EDS) diagram of a high entropy perovskite photochromic ceramic material (sample) prepared in Example 2 of the present invention. As shown in (a) in Figure 3, a partial area of the sample prepared in Example 2 is selected for element distribution analysis, and (b), (c), (d), (e), (f), (g), and (h) in Figure 3 are respectively the distribution of Ba, Zr, Mg, Nb, Ta, Ti, and O elements in the selected area of the sample. Through analysis, it is found that the 7 elements are evenly distributed in the area, and there is no obvious element segregation, indicating that the synthesized sample is a high entropy perovskite ceramic material; some black areas can be seen in the 7 element distribution diagrams. This is because the grains in the selected area are not arranged at the same height, and there are some height differences, which leads to some blind areas in the probe scanning process, so black areas are shown. The above conclusions show that the preparation of high entropy perovskite ceramic materials can be achieved based on the technical solution of the present invention.

(IV) Photochromic phenomenon experiment:

Figure 4 is a photochromic photograph of the high entropy perovskite photochromic ceramic material (sample) prepared in Example 4; Figure 4 (a) is a photograph of the entire sample surface prepared in Example 4 when not irradiated with light, Figure 4 (b) is a photograph of part of the sample prepared in Example 4 after being irradiated with light of 365nm wavelength for 0.5s at room temperature, Figure 4 (c) is a photograph of part of the sample prepared in Example 4 after being irradiated with light of 365nm wavelength for 120s at room temperature, and Figure 4 (d) is a photograph of the color comparison of the part of the sample prepared in Example 4 irradiated with light of 365nm wavelength for 120s and the part not irradiated with light.

From Figure 4 (a), it can be seen that the surface of the sample not irradiated by 365nm wavelength light is light yellow, and from Figure 4 (b), it can be seen that the surface of the sample after being irradiated by 365nm wavelength light for 0.5s is light brown, indicating that the sample undergoes a rapid photochromic phenomenon under 365nm wavelength light irradiation and exhibits a more obvious color change on the sample surface. From Figure 4 (c), it can be seen that the surface of the sample after being irradiated by 365nm wavelength light for 120s is dark brown, and from Figure 4 (d), it can be seen that the color contrast of the sample before and after being irradiated by 365nm wavelength light for 120s is extremely obvious, indicating that the sample can exhibit obvious photochromic phenomenon under 365nm wavelength light irradiation.

(V) Photochromic performance experiment:

FIG5 is a spectrum of the surface reflectivity of the high entropy perovskite photochromic ceramic material (sample) prepared in Examples 1 to 4 at room temperature, the surface reflectivity after being irradiated with a 365 nm laser for 120 seconds, and the surface reflectivity after being heated at 250° C. for 60 seconds; (a), (b), (c), and (d) in FIG5 correspond to the reflectivity spectra of the samples prepared in Examples 1 to 4, and the three lines in each figure correspond to:

(1) Initial state: The reflectance spectrum of the sample is tested at room temperature;

(2) Irradiation state: Four samples were placed under 365 nm wavelength light for 120 s at room temperature and then their reflectance spectra were tested;

(3) Recovery state: The sample is placed in a heating environment at 250°C for 60 seconds, then placed in a room temperature environment to cool down, and the reflectance spectrum of the sample is tested after it cools down;

It can be clearly seen from Figure 5 that after the sample was irradiated with light of 365nm wavelength for 120s, the reflectivity of the sample surface dropped sharply. After the sample was placed in an environment of 250°C and heated for 60s, the reflectivity of the sample surface returned to its initial state. The reflectivity changes of the samples prepared by Examples 2 and 4 before and after irradiation were relatively large, indicating that the samples with Ti ⁴⁺ participation were more conducive to the excellent photochromic properties exhibited by the samples than those with Sn ⁴⁺ participation. All four samples showed excellent reversible photochromic properties, indicating that the preparation of high-entropy perovskite ceramic materials can be achieved based on the technical solution of the present invention, and the regulation of its composition by utilizing the characteristic that there are many defects inside the high-entropy material makes the samples show more outstanding photochromic properties.

The present invention proposes a high-entropy perovskite ceramic material with a new main component, successfully synthesizes a high-entropy perovskite photochromic ceramic material with a stable single-phase structure through a high-temperature solid-phase method, and further specifically designs its physical and chemical properties to make it exhibit obvious photochromic phenomena. The present invention realizes the preparation of a single-phase new high-entropy perovskite photochromic ceramic material.

The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims (7)

1. The high-entropy perovskite photochromic ceramic material is characterized by having reversible photochromic performance, wherein the chemical formula of the high-entropy perovskite photochromic ceramic material is ：Ba(Zr_0.2Mg_0.2Nb_0.2Ta_0.2Sn_0.2)O₃、Ba(Zr_0.2Mg_0.2Nb_0.2Ta_0.2Ti_0.2)O₃、Ba(Zr_0.2Zn_0.2Nb_0.2Ta_0.2Sn_0.2)O₃ or Ba (Zr _0.2Zn_0.2Nb_0.2Ta_0.2Ti_0.2)O₃;

the preparation method of the high-entropy perovskite photochromic ceramic material comprises the following steps:

step 1, mixing and ball milling metal carbonate and/or metal oxide corresponding to the constituent elements of the high-entropy perovskite photochromic ceramic material to obtain a mixed material;

step 2, drying the mixed material to obtain high-entropy perovskite ceramic powder;

step 3, calcining the high-entropy perovskite ceramic powder to obtain the high-entropy perovskite photochromic ceramic material;

In the step 3, the calcination is two-stage calcination, specifically: first-stage calcination, wherein the calcination is carried out for 3-9 hours at 1200-1300 ℃; and the second stage of calcination, wherein the temperature is 1400-1450 ℃ for 3-9 h.

2. The high-entropy perovskite photochromic ceramic material according to claim 1, wherein in step 1, the ball milling is specifically wet ball milling, and the co-milling solvent is distilled water and/or absolute ethyl alcohol; the ball milling time is 12-48 h.

3. The high entropy perovskite photochromic ceramic material of claim 1 wherein in step 2, the drying treatment is carried out at a temperature of 50 to 150 ℃ for a period of 18 to 36 hours.

4. The high entropy perovskite photochromic ceramic material of claim 1 further comprising the steps of grinding and compression molding after the first stage of calcination is completed.

5. The high entropy perovskite photochromic ceramic material of claim 1 further comprising the steps of polishing and ultrasonic cleaning after the second stage of calcination is completed.

6. The use of the high entropy perovskite photochromic ceramic material of claim 1 in the field of storage and anti-counterfeiting.

7. A photochromic anti-counterfeiting material comprising the high-entropy perovskite photochromic ceramic material of claim 1.