Inorganic photochromic material as well as preparation method and application thereof

Abstract

The invention relates to the field of inorganic photochromic materials, in particular to an inorganic photochromic material and a preparation method and application thereof. Compared with the prior art, according to the preparation method provided by the invention, potassium carbonate, bismuth oxide and titanium dioxide with the molar ratio of potassium to bismuth to titanium being 1: 3: (4-x) are used as raw materials, x is greater than or equal to 0 and less than or equal to 1, and the inorganic photochromic material with good photochromic performance and photochromic reversibility is prepared through high-temperature calcination at 900-1000 DEG C. The preparation method is simple in step, raw materials are easy to obtain, the preparation cost is low, an irradiation light source needed by the prepared inorganic photochromic material is a common 365 nm ultraviolet light source, the application cost is low, and therefore the technical problem that an existing inorganic photochromic material cannot be suitable for large-scale industrial application is solved. Experimental results show that the inorganic photochromic material prepared by the preparation method disclosed by the invention can be successfully used for preparing an anti-counterfeiting encryption material.

Description

Technical Field

[0001] The invention relates to the field of inorganic photochromic materials, and in particular to an inorganic photochromic material and a preparation method and application thereof. Background Art

[0002] Inorganic photochromic materials refer to a class of materials that can change color after being stimulated by a light source. Specifically, under the irradiation of light of a specific wavelength, color centers are formed in the inorganic photochromic material, which causes the inorganic photochromic material to selectively absorb visible light, thereby causing the inorganic photochromic material to produce a color change visible to the naked eye, and can be bleached by thermal stimulation or light stimulation and restored to its original state. Using this characteristic, inorganic photochromic materials can be applied to anti-counterfeiting encryption, information storage, optical switches and other fields.

[0003] Some shortcomings of common inorganic photochromic materials have limited their large-scale industrial applications in the fields of anti-counterfeiting encryption, information storage, optical switching, etc. For example, although titanium dioxide photochromic materials can produce obvious color changes after irradiation and have good photochromic properties, their photochromic reversibility is poor. 0.5 Bi 2.5 Although Nb2O9:Er photochromic materials have good photochromic reversibility, their photochromic color change is not obvious. Germanate and tungstate photochromic materials require raw materials that are difficult to obtain and are expensive, making their preparation costs high. 7-x Er x Ti4NbO 21 Ceramics require a 405nm blue-violet laser as an irradiation light source, which makes its application cost relatively high. The above factors make existing inorganic photochromic materials unsuitable for large-scale industrial applications. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, provide an inorganic photochromic material and a preparation method and application thereof, and solve the technical problem that the existing inorganic photochromic materials are not suitable for large-scale industrial applications.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing an inorganic photochromic material, comprising the following steps: According to the molar ratio of potassium, bismuth and titanium being 1:3:4-x, potassium carbonate, bismuth oxide and titanium dioxide are used as raw materials, the raw materials are mixed and dispersed uniformly by wet grinding, and dried and ground to obtain a precursor; the precursor is subjected to high-temperature calcination treatment and then ground to obtain an inorganic photochromic material; wherein 0≤x≤1, the calcination temperature of the high-temperature calcination treatment is 900℃~1000℃, and the chemical formula of the inorganic photochromic material is KBi3Ti 4-x O 13-2x .

[0006] Compared with the prior art, the preparation method provided by the present invention uses potassium carbonate, bismuth oxide and titanium dioxide with a molar ratio of potassium, bismuth and titanium of 1:3:4-x as raw materials, 0≤x≤1, and undergoes high-temperature calcination at 900℃~1000℃, so that the prepared inorganic photochromic material forms a large number of oxygen vacancy defects, and 365nm ultraviolet light irradiation causes the oxygen vacancies to capture photogenerated electrons and convert them into single ionized oxygen vacancies to form F-type color centers, so that the inorganic photochromic material has good photochromic performance and photochromic reversibility. The preparation method of the present invention has simple steps, easy to obtain raw materials, and has a low preparation cost. The 365nm ultraviolet light source required for the inorganic photochromic material prepared by the present invention is relatively common, and there is no need to use a high-power laser or xenon lamp as an irradiation light source, which has a low application cost and is easy to apply. 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, solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0007] Optionally, the grinding time of the grinding process is 0.5h to 1h.

[0008] Optionally, the alcohol solvent is ethanol.

[0009] Optionally, the heating rate of the high temperature calcination treatment is 3°C / min to 5°C / min.

[0010] Optionally, the drying temperature is 80°C to 100°C.

[0011] Optionally, the wet grinding comprises the following steps: using an alcohol solvent as a grinding medium, and mixing and grinding the raw material with the alcohol solvent.

[0012] Optionally, the alcohol solvent is ethanol.

[0013] The present invention also provides an inorganic photochromic material prepared by the above-mentioned preparation method of the inorganic photochromic material, wherein the chemical formula of the inorganic photochromic material is KBi3Ti 4-x O 13-2x , where 0≤x≤1.

[0014] Optionally, the inorganic photochromic material has a coloring effect under 365nm ultraviolet light irradiation.

[0015] The present invention also provides a use of the above-mentioned inorganic photochromic material in preparing anti-counterfeiting encryption materials.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method provided by the present invention uses potassium carbonate, bismuth oxide and titanium dioxide with a molar ratio of potassium, bismuth and titanium of 1:3:4-x as raw materials, 0≤x≤1, and undergoes high-temperature calcination at 900℃~1000℃, so that the prepared inorganic photochromic material forms a large number of oxygen vacancy defects, and 365nm ultraviolet light irradiation causes the oxygen vacancies to capture photogenerated electrons and convert them into single ionized oxygen vacancies to form F-type color centers, so that the inorganic photochromic material has good photochromic properties and photochromic reversibility. The preparation method of the present invention has simple steps, easy to obtain raw materials, and has a low preparation cost. The 365nm ultraviolet light source required for the inorganic photochromic material prepared by the present invention is relatively common, and there is no need to use a high-power laser or xenon lamp as an irradiation light source, which has a low application cost and is easy to apply. 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, solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0017] 2. The experimental results show that the color of the inorganic photochromic material changes significantly before and after photochromism, and the difference in light absorption rate is large; after being subjected to 5 times of alternating ultraviolet irradiation and thermal stimulation, the photochromic performance of the inorganic photochromic material does not decrease significantly, indicating that the inorganic photochromic material prepared by the preparation method of the present invention has good photochromic performance and photochromic reversibility, and can be successfully used to prepare anti-counterfeiting encryption materials. Moreover, photochromism can be achieved using a 365nm portable ultraviolet lamp, without the need to use a high-power laser or xenon lamp as an irradiation light source, which can further save costs and facilitate application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the X-ray diffraction pattern of the inorganic photochromic material prepared in Example 1 of the present invention.

[0019] Figure 2 This is the X-ray photoelectron spectrum of the inorganic photochromic material prepared in Example 2 of the present invention.

[0020] Figure 3 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 1 of the present invention before and after being irradiated with 365nm ultraviolet light for 15 minutes.

[0021] Figure 4 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 2 of the present invention before and after being irradiated with 365nm ultraviolet light for 15 minutes.

[0022] Figure 5 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Example 3 of the present invention before and after being irradiated with 365nm ultraviolet light for 15 minutes.

[0023] Figure 6 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Comparative Example 1 of the present invention before and after being irradiated with 365nm ultraviolet light for 15 minutes.

[0024] Figure 7 The absorption spectrum and photochromic photograph of the inorganic photochromic material prepared in Comparative Example 2 of the present invention before and after being irradiated with 365nm ultraviolet light for 15 minutes.

[0025] Figure 8 This is a graph showing the absorbance variation of the inorganic photochromic material prepared in Example 3 of the present invention during the photochromic reversibility test. DETAILED DESCRIPTION

[0026] In order to solve the above technical problems, the present invention provides an inorganic photochromic material and a preparation method and application thereof. The technical scheme and embodiments of the present invention are now described in detail in conjunction with the accompanying drawings.

[0027] The technical solution adopted by the present invention is as follows: The inorganic photochromic material and the preparation method thereof according to the embodiment of the present invention are described in detail below.

[0028] An embodiment of the present invention provides a method for preparing an inorganic photochromic material, comprising: According to the molar ratio of potassium, bismuth and titanium being 1:3:4-x, potassium carbonate, bismuth oxide and titanium dioxide are used as raw materials, placed in a mortar, added with ethanol and ground and mixed for 0.5h to 1h, placed in an oven for drying at 80°C to 100°C, taken out of the mortar and continued to grind for 0.5h to 1h, the mixture is put into a crucible, placed in a high-temperature furnace and calcined 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.

[0029] Wherein, 0≤x≤1, the calcination temperature of the high temperature calcination treatment is 900℃~1000℃, and the chemical formula of the inorganic photochromic material is KBi3Ti 4-x O 13-2x .

[0030] It should be noted that calcination at 900℃~1000℃ is to obtain KBi3Ti4-x O 13-2x And ensure that the inorganic photochromic material contains more oxygen vacancy defects. After irradiation with 365nm ultraviolet light, the oxygen vacancies capture photogenerated electrons and transform into single ionized oxygen vacancies to form F-type color centers, which greatly improves the selective absorption of visible light, thereby showing obvious macroscopic color changes.

[0031] The heating rate of the high temperature calcination treatment is 3°C / min to 5°C / min.

[0032] It should be noted that the above-mentioned grinding medium is ethanol. Ethanol as a wet grinding medium can ensure that potassium carbonate, bismuth oxide and titanium dioxide are fully mixed and uniform.

[0033] In general, the inorganic photochromic material prepared by the above preparation method is in powder form, the preparation process is safe, can be prepared directly in the air, does not require the use of inert or reducing gas protection, has a low synthesis temperature, and is easy to operate. The prepared inorganic photochromic material has excellent photochromic properties and can be used for multi-purpose applications such as anti-counterfeiting encryption, information storage, and optical switches.

[0034] The embodiment of the present invention also provides an inorganic photochromic material, whose chemical formula is KBi3Ti 4-x O 13-2x , wherein 0≤x≤1. The inorganic photochromic material is prepared by the above-mentioned preparation method of the inorganic photochromic material.

[0035] Inorganic photochromic materials can produce photochromic phenomena when irradiated under a 365nm portable ultraviolet lamp. The samples have obvious color changes before and after the photochromism, from light yellow to dark gray. The samples have a large difference in light absorption rate before and after the photochromism, and can be used in the production of anti-counterfeiting encryption materials.

[0036] Inorganic photochromic materials have a large number of oxygen vacancy defects. After irradiation with 365nm ultraviolet light, the oxygen vacancies capture photogenerated electrons and convert them into singly ionized oxygen vacancies, forming F-type color centers, which greatly improve the selective absorption of visible light, thereby showing obvious macroscopic color changes.

[0037] After the inorganic photochromic material was subjected to five alternating UV irradiations and thermal stimulations, the photochromic performance did not decrease significantly, indicating that the inorganic photochromic material has good reversibility, thermal stability and fatigue resistance, and can be used in the field of anti-counterfeiting encryption.

[0038] The present invention is described in detail below through specific examples. The examples are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0039] Example 1 This embodiment provides a method for preparing an inorganic photochromic material, comprising: Weigh 0.6911 g of potassium carbonate, 6.9894 g of bismuth oxide and 2.3961 g of titanium dioxide into a mortar, add ethanol and grind and mix for 1 h, place in an oven at 80° C. to dry, take out the mortar and continue grinding for 0.5 h.

[0040] The uniformly mixed raw materials were placed in a crucible, placed in a high-temperature furnace and calcined at 950° C. for 3 h with a heating rate of 3° C. / min. After cooling to room temperature, the calcined product was ground for 0.5 h to obtain an inorganic photochromic material.

[0041] Example 2 This embodiment provides a method for preparing an inorganic photochromic material, comprising: Weigh 0.6911 g of potassium carbonate, 6.9894 g of bismuth oxide and 3.1948 g of titanium dioxide into a mortar, add ethanol and grind and mix for 0.5 h, place in an oven at 90° C. to dry, take out the mortar and continue grinding for 1 h.

[0042] The uniformly mixed raw materials were placed in a crucible, placed in a high-temperature furnace and calcined 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.

[0043] Example 3 This embodiment provides a method for preparing an inorganic photochromic material, comprising: Weigh 0.6911 g of potassium carbonate, 6.9894 g of bismuth oxide, and 2.7955 g of titanium dioxide into a mortar, add ethanol, grind and mix for 1 h, place in an oven at 100° C. to dry, take out the mortar and continue grinding for 1 h.

[0044] The uniformly mixed raw materials were placed in a crucible, placed in a high-temperature furnace and calcined at 1000° C. for 4 h with a heating rate of 5° C. / min. After cooling to room temperature, the calcined product was ground for 1 h to obtain an inorganic photochromic material.

[0045] Comparative Example 1 This embodiment provides a method for preparing an inorganic photochromic material, comprising: Weigh 0.6911 g of potassium carbonate, 6.9894 g of bismuth oxide and 2.3961 g of titanium dioxide into a mortar, add ethanol and grind and mix for 1 h, place in an oven at 80° C. to dry, take out the mortar and continue grinding for 0.5 h.

[0046] The uniformly mixed raw materials were placed in a crucible, placed in a high-temperature furnace and calcined at 850° C. for 3 h with a heating rate of 3° C. / min. After cooling to room temperature, the calcined product was ground for 0.5 h to obtain an inorganic photochromic material.

[0047] Comparative Example 2 This embodiment provides a method for preparing an inorganic photochromic material, comprising: Weigh 0.6911 g of potassium carbonate, 6.9894 g of bismuth oxide and 2.3961 g of titanium dioxide into a mortar, add ethanol and grind and mix for 1 h, place in an oven at 80° C. to dry, take out the mortar and continue grinding for 0.5 h.

[0048] The uniformly mixed raw materials were placed in a crucible, placed in a high-temperature furnace and calcined at 1050° C. for 3 h with a heating rate of 3° C. / min. After cooling to room temperature, the calcined product was ground for 0.5 h to obtain an inorganic photochromic material.

[0049] Test 1: Microstructural analysis.

[0050] The inorganic photochromic material 1 prepared in Example 1 was analyzed for phase composition using an X'Pert3 Powder X-ray diffractometer. The results are as follows: Figure 1 shown. Figure 1 This is the X-ray diffraction pattern of the inorganic photochromic material prepared in Example 1 of the present invention. Figure 1 It can be seen that the diffraction peak is sharp, indicating that the crystallization effect is good, the main crystal phase is potassium bismuth titanate, and the content of other impurities is small, which shows that the preparation method of the present invention can successfully prepare inorganic photochromic materials.

[0051] The element composition of inorganic photochromic material 2 was tested using an ESCALAB 250Xi X-ray photoelectron spectrometer. The test results are shown in Figure 2 . Figure 2 This is the X-ray photoelectron spectrum of the inorganic photochromic material prepared in Example 2 of the present invention. Figure 2 It can be seen that the photoelectron spectrum peaks corresponding to K 2p, O 1s, Bi 4f and Ti 2p indicate that the sample contains K, O, Ti and Bi elements and does not contain other impurity elements, further indicating that the preparation method of the present invention can successfully prepare inorganic photochromic materials.

[0052] Test 2: Photochromic performance test.

[0053] Test materials: the inorganic photochromic materials prepared in Examples 1 to 3, and the inorganic photochromic materials prepared in Comparative Examples 1 and 2.

[0054] Test equipment: UV3600Plus ultraviolet-visible spectrophotometer, 8W 365nm portable ultraviolet lamp, and a metal plate with a hollow heart pattern.

[0055] Test method: Take appropriate amounts of the inorganic photochromic materials prepared in different embodiments, and first use a UV-visible spectrophotometer to test the absorption spectrum. Use a portable UV lamp to irradiate the inorganic photochromic material for 15 minutes, and then use a UV-visible spectrophotometer to test the absorption spectrum. The test band range of the UV-visible spectrophotometer is 200nm to 800nm.

[0056] Take appropriate amounts of the inorganic photochromic materials prepared in different embodiments to completely fill the mold, cover the sample with a metal plate with a hollow heart pattern, irradiate with a 365nm portable ultraviolet lamp for 15 minutes, and take photos of the inorganic photochromic material after removing the metal plate.

[0057] Test result analysis: The test results of the photochromic performance of the inorganic photochromic materials prepared in Examples 1 to 3 are shown in Figure 3 to Figure 5 The photochromic performance test results of the inorganic photochromic materials prepared in Comparative Examples 1 and 2 are shown in Figure 6 and Figure 7 .

[0058] from Figure 3 to Figure 5 It can be seen that compared with before UV irradiation, after 15 minutes of 365nm UV irradiation, in the visible light range, the inorganic photochromic materials prepared in Examples 1 to 3 have significantly enhanced light absorption; after 15 minutes of 365nm UV irradiation, obvious heart patterns appear on the surfaces of the inorganic photochromic materials prepared in Examples 1 to 3, indicating that obvious photochromic phenomena have occurred in the test samples. Among them, the area blocked by the mold is lighter in color, light yellow; the area where the heart pattern is formed is darker in color, dark gray, indicating that the color of the sample after UV irradiation changes from light yellow to dark gray, and the color change is significant, further indicating that the inorganic photochromic material before and after photochromic has a large difference in light absorption rate.

[0059] And from Figure 6 and Figure 7 It can be seen that the inorganic photochromic materials prepared in Comparative Examples 1 and 2 also undergo photochromism, but the color change of the samples after ultraviolet irradiation is not large, and the difference in light absorption rate of the samples before and after photochromism is also small, indicating that the photochromism is not obvious.

[0060] 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, which indicates that the calcination temperature during high-temperature calcination has a greater impact on the photochromic properties of the inorganic photochromic materials. When the calcination temperature during high-temperature calcination is 900°C to 1000°C, the prepared inorganic photochromic materials have better photochromic properties.

[0061] Test 3: Photochromic reversibility test.

[0062] Test material: the inorganic photochromic material prepared in Example 3.

[0063] Test equipment: UV3600Plus ultraviolet-visible spectrophotometer, 8W 365nm portable ultraviolet lamp, far-infrared microcrystalline electric heating plate.

[0064] Test method: First, use a UV3600Plus ultraviolet-visible spectrophotometer to test and record the original absorption spectrum of the inorganic photochromic material prepared in Example 3, and record the absorbance value of the inorganic photochromic material at 500 nm.

[0065] Thermal bleaching treatment: Use an 8W 365nm portable ultraviolet lamp to irradiate the inorganic photochromic material for 15 minutes, so that the inorganic photochromic material produces photochromism, and then use a UV-visible spectrophotometer to test and record the absorption spectrum of the inorganic photochromic material after photochromism, and record the absorbance value of the inorganic photochromic material after photochromism at 500nm. Use a far-infrared microcrystalline electric heating plate to heat stimulate the inorganic photochromic material after photochromism at 350°C. After the inorganic photochromic material after photochromism is cooled to room temperature, use a UV-visible spectrophotometer to test and record its absorption spectrum and record the absorbance value at 500nm. Repeat the thermal bleaching treatment operation 5 times for the inorganic photochromic material prepared in the same Example 3.

[0066] Test result analysis: Figure 8 This is a graph showing the absorbance variation of the inorganic photochromic material prepared in Example 3 of the present invention during the photochromic reversibility test.

[0067] from Figure 8 It can be seen that when the thermal bleaching treatment operation is cycled for 5 times, the relative absorbance of the inorganic photochromic material prepared in Example 3 of the present invention does not change significantly after each photochromic change or thermal stimulation. This shows that the photochromic performance of the inorganic photochromic material prepared in Example 3 of the present invention has good reversibility, and the inorganic photochromic material has thermal stability and fatigue resistance, and the inorganic photochromic material prepared in Example 3 of the present invention can be repeatedly used by thermal bleaching treatment. It further shows that the inorganic photochromic material prepared by the preparation method of the present invention has good photochromic reversibility and can be applied to anti-counterfeiting encryption, information storage, optical switches and other fields.

[0068] In summary, the inorganic photochromic material prepared by the preparation method provided in the embodiment of the present invention can produce a photochromic phenomenon under irradiation with a 365nm portable ultraviolet lamp. The inorganic photochromic material has an obvious macroscopic color change from light yellow to dark gray before and after the photochromic change, and the inorganic photochromic material has a large light absorption rate difference before and after the photochromic change. In addition, the inorganic photochromic material prepared by the preparation method of the present invention has good photochromic reversibility, which indicates that the inorganic photochromic material prepared by the preparation method of the present invention has good photochromic performance and photochromic reversibility, and can be successfully used to prepare anti-counterfeiting encryption materials.

[0069] And because the preparation method of the present invention has simple steps and the raw materials are easy to obtain, it has a low preparation cost. The inorganic photochromic material prepared by the present invention does not need to use a high-power laser or a xenon lamp as an irradiation light source, has a low application cost, and is easy to use. 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, solving the technical problem that existing inorganic photochromic materials cannot be applied to large-scale industrial applications.

[0070] The above description is only a preferred embodiment of the present invention, and the above specific embodiment is not intended to limit the present invention. Various deformations and modifications may occur within the scope of the technical concept of the present invention, and any modification, modification or equivalent replacement made by a person of ordinary skill in the art based on the above description shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing an inorganic photochromic material, characterized in that: The steps include: According to the molar ratio of potassium, bismuth and titanium being 1:3:4-x, potassium carbonate, bismuth oxide and titanium dioxide are used as raw materials, the raw materials are mixed and dispersed uniformly by wet grinding, and then dry-grinded to obtain a precursor; The precursor is subjected to high temperature calcination treatment and then grinding treatment to obtain an inorganic photochromic material; Wherein, 0≤x≤1, the calcination temperature of the high temperature calcination treatment is 900℃~1000℃, and the chemical formula of the inorganic photochromic material is KBi3Ti 4-x O 13-2x .

2. The method for preparing an inorganic photochromic material according to claim 1, characterized in that: The grinding time of the grinding process is 0.5h to 1h.

3. The method for preparing an inorganic photochromic material according to claim 1, characterized in that: The heating rate of the high temperature calcination treatment is 3°C / min to 5°C / min.

4. The method for preparing an inorganic photochromic material according to claim 1, characterized in that: The drying temperature is 80°C to 100°C.

5. The method for preparing an inorganic photochromic material according to claim 1, characterized in that: The wet grinding comprises the following steps: The alcohol solvent is used as a grinding medium, and the raw material and the alcohol solvent are mixed and ground.

6. The method for preparing an inorganic photochromic material according to claim 5, characterized in that: The alcohol solvent is ethanol.

7. An inorganic photochromic material obtained by the method for preparing an inorganic photochromic material according to any one of claims 1 to 6, characterized in that: The chemical formula of the inorganic photochromic material is KBi3Ti 4-x O 13-2x , where 0≤x≤1.

8. The inorganic photochromic material according to claim 7, characterized in that: The inorganic photochromic material has a coloring effect under 365nm ultraviolet light irradiation.

9. Use of the inorganic photochromic material according to claim 7 or 8 in the preparation of anti-counterfeiting encryption materials.

Images