Transparent photochromic ceramic material as well as preparation method and application thereof

Abstract

The invention provides a transparent photochromic ceramic material as well as a preparation method and application thereof, and belongs to the technical field of ceramic materials. According to the invention, the KNN ferroelectric ceramic is used as a matrix, and the second component (Sr0. 5Ba0. 5) (Zn1 / 3Bi2 / 3) O3 is introduced, so that the ceramic has light transmission performance; by controlling the adding amount of the second component, it is avoided that excessive Bi < 3 + > forms more pores during sintering, and the transparency of the material is reduced; by introducing a third component Pr6O11, more vacancy defects can be formed in the ceramic, and the number of color centers is effectively increased, so that the photochromic performance is enhanced; pr < 3 + > can coordinate Bi < 3 + > to inhibit grain growth and further reduce optical loss, so that the ceramic has a high fluorescence regulation ratio and keeps high transparency at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and particularly relates to a transparent photochromic ceramic material, a preparation method thereof and an application thereof. Background Art

[0002] Perovskite-type oxides have attracted strong interest due to their excellent physical properties (such as piezoelectricity, ferroelectricity and electromagnetic properties), and their phase structure and crystal structure can be regulated, making ion doping an effective method for optimizing their properties and realizing new functions. Transparent ferroelectric ceramics with ABO3-type perovskite structure have ferroelectric, piezoelectric and optoelectronic properties in addition to the inherent advantages of transparent ceramics. However, traditional ABO3-type perovskite-structured transparent ferroelectric ceramics (such as PZT) contain lead, which will cause harm to the environment and human body.

[0003] In recent years, lead-free transparent ferroelectric ceramics have been developed, such as alkali metal niobate ceramics, which have the characteristics of small piezoelectric constant, high piezoelectricity, large frequency constant and small density, and are an important alternative material to replace lead-based ceramics. Du et al. introduced Sr(Sc 0.5 Nb 0.5 )O3 with a tetragonal phase structure into K 0.5 Na 0.5 NbO3 (KNN) ceramics to form a pseudo-cubic phase with high symmetry, thereby increasing the optical transmittance in the visible light range to 60%; however, such alkali metal niobate ceramics only have good transparency and do not have photochromic ability, and their performance is relatively single. Yang et al. introduced SrZrO3 into KNN ceramics and doped a third component Sm2O3 to obtain good densification and a pseudo-cubic phase with high symmetry. The rare earth endows the ceramics with photochromic properties, and the fluorescence regulation ratio reaches 65.3%, but the transparency of the ceramics in the visible light region is only 45%. Fang et al. doped the rare earth element Er in 0.96K 0.5 Na 0.5 NbO3-0.04LiBiO3 ceramics to successfully prepare transparent photochromic ceramics with fluorescence properties, and the fluorescence regulation ratio reaches 65%, but the transparency in the visible light range is only 45%. It can be seen that improving the fluorescence performance of ceramics will lead to a decrease in transparency, and it is impossible to have a high fluorescence regulation ratio while ensuring transparency. Summary of the Invention

[0004] The purpose of the present invention is to provide a transparent photochromic ceramic material, a preparation method thereof and an application thereof. The transparent photochromic ceramic material provided by the present invention has both high transparency and fluorescence regulation ratio.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a transparent photochromic ceramic material, and the transparent photochromic ceramic material is Pr6O 11 doped 0.94(K 0.5 Na 0.5 )NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3 ceramic. In terms of mole percentage, the doping amount of Pr6O 11 in the transparent photochromic ceramic material is 0.04 - 0.1%.

[0007] Preferably, the transparent photochromic ceramic material has an ABO3 perovskite pseudo-cubic phase structure.

[0008] The present invention also provides a preparation method of the transparent photochromic ceramic material described in the above technical solution, including the following steps:

[0009] (1) According to the stoichiometric ratio, mix the potassium source, sodium source, niobium source, strontium source, bismuth source, zinc source, barium source and praseodymium source, and then perform primary ball milling, pre-sintering and secondary ball milling in sequence to obtain ceramic powder;

[0010] (2) Press the ceramic powder obtained in step (1) into a mold and then sinter it to obtain a transparent photochromic ceramic material.

[0011] Preferably, the pre-sintering temperature in step (1) is 840 - 860 °C, and the pre-sintering time is 1 - 3 h.

[0012] Preferably, the particle size of the ceramic powder obtained in step (1) is ≤ 0.1 mm.

[0013] Preferably, the sintering in step (2) includes first sintering and second sintering performed in sequence; the temperature of the first sintering is 550 - 650 °C, and the time is 120 - 180 min; the temperature of the second sintering is 1130 - 1160 °C, and the time is 180 - 240 min.

[0014] Preferably, the heating rate of the first sintering is 1 - 2 °C / min; the heating rate of the second sintering is 3 - 5 °C / min.

[0015] Preferably, the pressure for pressing into a mold in step (2) is 1 - 8 MPa.

[0016] Preferably, granulating the ceramic powder is also included before pressing into a mold in step (2).

[0017] The present invention also provides an application of the transparent photochromic ceramic material described in the above technical solution in optical fibers, solid-state lasers, optical storage, optical attenuators, smart windows or optical switches.

[0018] The present invention provides a transparent photochromic ceramic material, and the transparent photochromic ceramic material is Pr6O 11 -doped 0.94(K 0.5 Na 0.5 )NbO3-0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3 ceramic. In terms of mole percentage, the doping amount of Pr6O 11 in the transparent photochromic ceramic material is 0.04-0.1%. The present invention uses KNN ferroelectric ceramics as the matrix, and by introducing the second component (Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3, the ceramic has light transmission performance. Bi 3+ in the second component can improve the sintering activity of the material. During the sintering process, Bi 3+ can also inhibit the excessive growth of grains and improve the density of the ceramic, thereby facilitating the improvement of the light transmittance of the ceramic; by controlling the addition amount of the second component, it is avoided that too much Bi 3+ forms more pores (scattering centers) during sintering and reduces the transparency of the material; by introducing the third component Pr6O 11 , Pr 3+ has different ionic radii and valence states from those of the matrix and the second component elements, and more vacancy defects (maintaining electrical neutrality) can be formed inside the ceramic, effectively increasing the number of color centers and thus enhancing the photochromic performance; Pr 3+ can also coordinate with Bi 3+ to inhibit grain growth, further reduce light loss, and enable the ceramic to have a high fluorescence regulation ratio while maintaining a high transparency; by controlling the contents of the second component and the third component, the ceramic material has good light transmittance and reversible and stable fluorescence intensity regulation characteristics. The results of the examples show that the transparent photochromic ceramic material provided by the present invention has a transparency higher than 58.41% and a fluorescence regulation ratio higher than 61.62% in the 1100 nm band. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the transparency and photochromism of the ceramic materials provided in Examples 1-4 and Comparative Example 1 of the present invention;

[0020] Figure 2 It is an XRD pattern of the ceramic materials provided in Examples 1-4 and Comparative Example 1 of the present invention;

[0021] Figure 3 This is the transparency curve graph of the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 of the present invention;

[0022] Figure 4 This is the photochromic transparency modulation graph of the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 of the present invention under 10 light-thermal stimulation cycles;

[0023] Figure 5 This is the fluorescence intensity change curve of the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 of the present invention before and after 407 nm light irradiation for 1 min;

[0024] Figure 6 This is the photochromic modulation curve of fluorescence intensity of the ceramic material provided in Example 4 of the present invention under 10 light-thermal stimulation cycles. Detailed implementation manners

[0025] For all raw materials of the present invention, there is no particular limitation on their sources, and they can be purchased on the market or prepared according to conventional methods well-known to those skilled in the art.

[0026] For all raw materials of the present invention, there is no particular limitation on their purity. The present invention preferably uses high-purity raw materials with a purity higher than 99.9%.

[0027] The present invention provides a transparent photochromic ceramic material, and the transparent photochromic ceramic material is Pr6O 11 doped 0.94(K 0.5 Na 0.5 )NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3 ceramic. In terms of mole percentage, the doping amount of Pr6O 11 in the transparent photochromic ceramic material is 0.04 - 0.1%.

[0028] In the present invention, in terms of mole percentage, the doping amount of Pr6O 11 in the transparent photochromic ceramic material is 0.04 - 0.1%, preferably 0.06 - 0.08%; as an implementation manner of the present invention, the doping amount of Pr6O 11 in the transparent photochromic ceramic material can be 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1%. By limiting the doping amount of Pr6O 11 within the above range, the ceramic can have a high fluorescence regulation ratio while maintaining high transparency, and avoid excessive doping amount from reducing the transparency of the ceramic.

[0029] In the present invention, the transparent photochromic ceramic material preferably has a perovskite pseudo-cubic phase structure of ABO3. The ceramic with the perovskite pseudo-cubic phase structure of ABO3 has good transparency. By regulating the amounts of the second component and the third component in the present invention, the ceramic has a pseudo-cubic phase structure in which the tetragonal phase and the cubic phase coexist, further improving the transparency of the ceramic.

[0030] The present invention also provides a method for preparing the transparent photochromic ceramic material according to the above technical solution, comprising the following steps:

[0031] (1) According to the stoichiometric ratio, mix the potassium source, sodium source, niobium source, strontium source, bismuth source, zinc source, barium source and praseodymium source, and then successively perform primary ball milling, pre-sintering and secondary ball milling to obtain ceramic powder.

[0032] (2) Press and mold the ceramic powder obtained in step (1) and then sinter it to obtain the transparent photochromic ceramic material.

[0033] In the present invention, the potassium source, sodium source, niobium source, strontium source, bismuth source, zinc source, barium source and praseodymium source are mixed according to the stoichiometric ratio and then successively subjected to primary ball milling, pre-sintering and secondary ball milling to obtain ceramic powder.

[0034] The present invention does not particularly limit the specific types of the raw materials, and conventional raw materials in the art can be used. In the examples of the present invention, the potassium source is potassium carbonate, the sodium source is sodium carbonate, the niobium source is niobium pentoxide, the strontium source is strontium carbonate, the bismuth source is bismuth oxide, the zinc source is zinc oxide, the barium source is barium carbonate, and the praseodymium source is praseodymium oxide.

[0035] The present invention does not particularly limit the mixing method, and a conventional mixing method in the art can be used.

[0036] The present invention does not particularly limit the specific parameters of the primary ball milling, and conventional ball milling parameters in the art can be adopted. As an embodiment of the present invention, the primary ball milling can be wet ball milling, the ball milling medium of the wet ball milling can be ethanol, and the dosage relationship between the raw material and the ball milling medium is 1 g:(5-8) mL; the grinding balls of the primary ball milling can be a mixture of zirconium balls with sizes of 5 mm and 8 mm, and the mass ratio of the 5 mm zirconium balls to the 8 mm zirconium balls can be (1.5-2.5):1 or 2:1, and the ball-to-material ratio can be (1.5-2.5):1 or 2:1; the rotation speed of the primary ball milling can be 350-450 r / min or 410 r / min; the time of the primary ball milling can be 22-26 h or 24 h. As an embodiment of the present invention, a mixed powder is obtained after the primary ball milling, and the particle size of the mixed powder is ≤0.1 mm. The present invention enables the raw materials to be fully mixed through the primary ball milling and refines the particle size of the raw materials, which is beneficial to improving the uniformity of the ceramic during the subsequent sintering process.

[0037] In the present invention, it is preferred to sequentially dry and screen the obtained powder after the primary ball milling to obtain a mixed powder. As an embodiment of the present invention, the drying temperature can be 65-85°C or 80°C, and the drying time can be 2-4 h or 3 h; the screening can use a 100-mesh sieve. The present invention does not particularly limit the specific operations of the drying and screening, and conventional operation methods in the art can be adopted.

[0038] In the present invention, the temperature of the pre-sintering is preferably 840-860°C, more preferably 850°C; the time of the pre-sintering is preferably 1-3 h, more preferably 2 h. The present invention does not particularly limit the specific operation of the pre-sintering, and conventional pre-sintering methods in the art can be adopted. As an embodiment of the present invention, the heating rate of the pre-sintering can be 3-5°C / min, and the cooling method after the pre-sintering can be furnace cooling. The present invention enables the raw materials to form the main crystal phase through the pre-sintering and removes the bound water, organic matter and other volatile impurities in the raw materials; the parameters of the pre-sintering within the above range can reduce the deformation of the green body caused by excessive shrinkage rate during the sintering process, which is beneficial to the reaction of the oxide raw materials and the carbonate raw materials to form a solid solution.

[0039] In the present invention, it is preferred that the secondary ball milling has the same parameters as the aforementioned primary ball milling, which will not be elaborated here. The present invention refines the powder obtained by the pre-sintering through the secondary ball milling, which is beneficial to further improving the uniformity of the ceramic.

[0040] In the present invention, it is preferred to sequentially dry and screen the mixed powder after the secondary ball milling, and the drying and screening are preferably the same as the drying and screening parameters of the mixed powder after the aforementioned primary ball milling, which will not be elaborated here.

[0041] In the present invention, the particle size of the ceramic powder is preferably ≤0.1 mm, more preferably 0.01 - 0.05 mm. When the particle size of the ceramic powder is within the above range, it is beneficial to improve the uniformity and denseness of the ceramic, and further improve the transparency of the ceramic.

[0042] After obtaining the ceramic powder, in the present invention, the ceramic powder is pressed into a shape and then sintered to obtain a transparent photochromic ceramic material.

[0043] In the present invention, it is preferred to granulate the ceramic powder first and then press it into a shape. There is no particular limitation on the specific operation of the granulation in the present invention, and a conventional granulation method in the art can be used. As an embodiment of the present invention, the binder used for granulation can be an aqueous solution of polyvinyl alcohol, and the mass concentration of the aqueous solution of polyvinyl alcohol can be 5 - 8%, or can also be 7%; the specific process of granulation can be: adding the binder dropwise to the ceramic powder, grinding evenly after each drop is added and then adding the next drop until the ground ceramic powder presents a snowflake shape, stopping adding the binder to obtain snowflake-shaped ceramic powder. By granulating the ceramic powder in the present invention, the viscosity of the ceramic powder can be increased, which is beneficial to pressing into a shape.

[0044] After obtaining the snowflake-shaped ceramic powder, in the present invention, it is preferred to dry and screen the snowflake-shaped ceramic powder, and the parameters of the drying and screening are preferably the same as those of the drying and screening of the mixed powder after the first-stage ball milling, which will not be elaborated here.

[0045] In the present invention, the snowflake-shaped ceramic powder is pressed into a shape to obtain a tablet. The pressure for the pressing into a shape is preferably 1 - 8 MPa, more preferably 3 - 5 MPa; as an embodiment of the present invention, the pressure for the pressing into a shape can be 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa or 7 MPa. By using the above pressure for pressing into a shape in the present invention, the tablet can be made stronger, which is beneficial to reducing the risk of ceramic cracking during the subsequent sintering process.

[0046] As an embodiment of the present invention, the time for the pressing into a shape can be 1 - 3 min, and the mold used for the pressing into a shape can be a mold with a punch diameter of 12 mm.

[0047] In the present invention, the sintering preferably includes first sintering and second sintering carried out in sequence.

[0048] In the present invention, the temperature of the first sintering is preferably 550 to 650 °C, more preferably 580 to 620 °C; as an embodiment of the present invention, the temperature of the first sintering can be 560 °C, 570 °C, 590 °C, 600 °C, 610 °C or 640 °C. The time of the first sintering is preferably 120 to 180 min, more preferably 140 to 160 min; as an embodiment of the present invention, the time of the first sintering can be 130 min, 150 min, 160 min or 170 min. By the first sintering and limiting the parameters of the first sintering within the above ranges, the present invention is conducive to fully discharging the binder added in the granulation process, as well as the residual bound water, CO2 and other volatile impurities, and avoiding the deformation of the green body due to excessive shrinkage rate during the subsequent sintering process.

[0049] In the present invention, the heating rate of the first sintering is preferably 1 to 2 °C / min. When the heating rate is within the above range, it is conducive to reducing the porosity of the material, making the material more dense, and avoiding excessive growth of grains due to too fast heating rate, reducing the density of the material, and thus affecting the transparency.

[0050] In the present invention, the temperature of the second sintering is preferably 1130 to 1160 °C, more preferably 1140 to 1150 °C; as an embodiment of the present invention, the temperature of the second sintering can be 1130 °C, 1135 °C, 1140 °C, 1145 °C, 1150 °C or 1155 °C. The time of the second sintering is preferably 180 to 240 min, more preferably 200 to 220 min; as an embodiment of the present invention, the time of the second sintering can be 190 min, 200 min, 210 min or 230 min. By the second sintering and limiting the parameters of the second sintering within the above ranges, the present invention is conducive to reducing the grain size and porosity of the material, improving the density of the material, and further improving the transparency of the material; at the same time, hetero-valent elements can also diffuse into the crystal lattice to form defects, which is conducive to the formation of color centers and further enhances the photochromic reaction.

[0051] In the present invention, the heating rate of the second sintering is preferably 3 to 5 °C / min. When the heating rate is within the above range, it is conducive to reducing the porosity of the material, making the material more dense, and avoiding excessive growth of grains due to too fast heating rate, reducing the density of the material, and thus affecting the transparency.

[0052] In the present invention, the sintering is preferably carried out in a closed environment; carrying out sintering in a closed environment can increase the element concentration in the closed environment, reduce the volatilization of sodium and potassium metals, and is conducive to ensuring the mass relationship of each element.

[0053] The preparation method provided by the present invention is simple to operate, the raw materials are easy to obtain, the equipment requirements are low, the performance of the obtained product is stable, and it is easy to promote.

[0054] The present invention also provides an application of the transparent photochromic ceramic material described in the above technical solution in optical fibers, solid-state lasers, optical storage, optical attenuators, smart windows or optical switches.

[0055] The present invention does not particularly limit the specific manner of the application, and the conventional application manner in the art can be adopted.

[0056] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Example 1

[0058] A transparent photochromic ceramic material, with the composition of [0.94K 0.5 Na 0.5 NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3Bi 2 / 3 )O3] - 0.04 mol% Pr6O 11 , denoted as x = 0.04.

[0059] The preparation method is as follows:

[0060] (1) Weighing ingredients: Use an electronic balance to accurately weigh 1.6403 g of K2CO3 (99.99%), 1.2478 g of Na2CO3 (99.99%), 6.2471 g of Nb2O5 (99.99%), 0.2216 g of SrCO3 (99.99%), 0.4660 g of Bi2O3 (99.99%), 0.0813 g of ZnO (99.99%), 0.2963 g of BaCO3, and 0.0204 g of Pr6O 11 (99.99%).

[0061] (2) Primary ball milling: Pour the raw materials weighed in step (1) into a ball milling tank, then add 60 mL of ethanol as the ball milling medium, shake the ball milling tank to uniformly disperse the raw materials in ethanol, and then add two kinds of zirconia balls with sizes of 5 mm and 8 mm. The ball-to-material ratio is 2:1, and the quantity ratio of the zirconia balls with sizes of 5 mm and 8 mm is 2:1. Then ball mill for 24 h on a drum-type ball mill, control the rotation speed of the ball mill at 410 r / min, and the particle size of the mixed powder obtained after ball milling is ≤ 0.1 mm.

[0062] (3) Drying and sieving: First, use a ladle to separate the mixed powder obtained in step (2) from the zirconium balls. Then, pour the mixed powder into a petri dish and place it in a drying oven for heating. The temperature is controlled at 80 °C and heated for 3 h until all the ethanol in the petri dish has evaporated. The dried mixed powder is sieved through a 100-mesh sieve, and the sieved mixed powder is reserved for use.

[0063] (4) Pre-sintering: Place the mixed powder obtained in step (3) in a crucible, and place a cover on the crucible to seal it to prevent impurities from falling into the crucible during pre-sintering and contaminating the mixed powder. Heat from room temperature (25 °C) to 860 °C at a heating rate of 4 °C / min, hold for 3 h, and then cool with the furnace to obtain the primary ceramic powder.

[0064] (5) Secondary ball milling: First, pour the primary ceramic powder obtained in step (4) into a ball milling tank, then add 50 mL of ethanol, shake the ball milling tank to evenly disperse the raw materials in the ethanol, and then add two kinds of zirconium balls with different sizes of 5 mm and 8 mm. The ball-to-material ratio is 2:1, and the quantity ratio of the zirconium balls with sizes of 5 mm and 8 mm is 2:1. Then, ball mill for 24 h on a drum-type ball mill. The rotation speed of the ball mill is controlled at 410 r / min, and the particle size of the ceramic powder obtained after ball milling is ≤ 0.02 mm.

[0065] (6) Drying and sieving: First, use a ladle to separate the ceramic powder obtained in step (5) from the zirconium balls. Then, pour the ceramic powder into a petri dish, place the petri dish containing the ceramic powder in a drying oven for heating. The temperature is controlled at 80 °C and heated for 3 h until all the ethanol in the ceramic powder has evaporated. The dried ceramic powder is sieved through a 100-mesh sieve, and the sieved ceramic powder is reserved for use.

[0066] (7) Granulation: Gradually dropwise add an aqueous solution of polyvinyl alcohol with a mass concentration of 7% to the ceramic powder obtained in step (6). After each drop is added, fully grind until it is uniform and then add the next drop until the ground ceramic powder shows a snowflake shape and stop adding the aqueous solution of polyvinyl alcohol to obtain the snowflake-shaped ceramic powder.

[0067] (8) Drying and sieving: Place the snowflake-shaped ceramic powder obtained in step (7) in an oven and dry it at 80 °C for 6 h to make the powder completely dry. Then, sieve it through a 100-mesh sieve, and the sieved snowflake-shaped ceramic powder is reserved for use.

[0068] (9) Tabletting: Weigh 0.38 g of the snowflake-shaped ceramic powder obtained in step (8) and put it into a mold with a punch diameter of 12 mm. Hold the pressure at 5 MPa for 1 min for tabletting to obtain a tablet.

[0069] (10) Sintering: Lay a layer of snowflake-shaped ceramic powder on the surface of the zirconium plate. Place the tablet obtained in step (9) on the surface of the zirconium plate covered with the snowflake-shaped ceramic powder, and then sprinkle a little snowflake-shaped ceramic powder on the surface of the tablet. Cover the crucible on the tablet and use zirconia powder to seal the gap between the inverted crucible and the zirconium plate. Place the crucible containing the sample in a muffle furnace for sintering. Heat from room temperature to 600 °C at a heating rate of 2 °C / min, hold for 120 min, then heat to 1160 °C at a heating rate of 3 °C / min and hold for 180 min. Cool with the furnace to obtain a transparent photochromic ceramic material.

[0070] Example 2

[0071] A transparent photochromic ceramic material with a composition of [0.94K 0.5 Na 0.5 NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3Bi 2 / 3 )O3] - 0.06 mol% Pr6O 11 , denoted as x = 0.06. The preparation method is the same as that of Example 1, except that the mass of Pr6O 11 is 0.0306 g.

[0072] Example 3

[0073] A transparent photochromic ceramic material with a composition of [0.94K 0.5 Na 0.5 NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3Bi 2 / 3 )O3] - 0.08 mol% Pr6O 11 , denoted as x = 0.08. The preparation method is the same as that of Example 1, except that the mass of Pr6O 11 is 0.0408 g.

[0074] Example 4

[0075] A transparent photochromic ceramic material with a composition of [0.94K 0.5 Na 0.5 NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3Bi 2 / 3 )O3] - 0.1 mol% Pr6O 11 , denoted as x = 0.1. The preparation method is the same as that of Example 1, except that the mass of Pr6O 11 is 0.0510 g.

[0076] Comparative Example 1

[0077] A ceramic material with a composition of [0.94K 0.5 Na 0.5 NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3], denoted as x = 0. The preparation method is the same as that of Example 1, except that Pr6O 11 is not added.

[0078] Test Example 1

[0079] The ceramic materials provided in Examples 1 to 4 and Comparative Example 1 were successively irradiated with 407 nm light for 1 min and thermally stimulated at 150 °C (V-D100 heating stage) for 1 min. The changes in the ceramic materials are as Figure 1 shown. The 5 wafers in the upper part of the figure are the states of Example 1, Example 2, Example 3, Example 4, and Comparative Example 1 before illumination from left to right; the 5 wafers in the lower part of the figure are the states of Example 1, Example 2, Example 3, Example 4, and Comparative Example 1 after illumination from left to right. It can be seen from Figure 1 that the ceramic materials provided in Examples 1 to 4 changed from yellowish-green to dark gray under illumination and returned to the original state after 1 min of thermal stimulation at 150 °C, while the color change of Comparative Example 1 was relatively less.

[0080] Test Example 2

[0081] The ceramic materials provided in Examples 1 to 4 and Comparative Example 1 were detected using an X-ray diffractometer, and the XRD patterns are as Figure 2 shown. Figure 2 The enlarged view on the right side in Figure 2 shows the diffraction angle 2θ ranging from 44 to 47°. It can be seen from 3+ that the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 are all pure perovskite structures without the formation of a second phase and are all in the pseudo-cubic phase structure; the characteristic peaks at 44 - 47° of Examples 1 to 4 are all shifted to higher angles compared to Comparative Example 1 because Pr 11 with a small ionic radius enters the lattice, reducing the interplanar spacing; the peak positions of Examples 1 to 4 do not change much, but when the Pr6O 3+ content is greater than 0.06 mol%, it is observed that the left side of the peak shape gradually separates, indicating that Pr

[0082] Test Example 3

[0083] The transparency of the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 was tested using a UV-6100 ultraviolet-visible spectrophotometer in the range of 200 to 1100 nm, and the transparency curve graph was obtained as Figure 3 shown. It can be seen from Figure 3 that the transparencies of Examples 1 to 4 in the 1100 nm band were 60.23%, 64.66%, 60.33%, and 58.41% respectively; the transparency of the comparative example in the 1100 nm band was 40.61%. It can be seen that the transparencies of the ceramic materials prepared in Examples 1 to 4 maintained a relatively high level. Pr doping can improve the transparency of ceramics and achieve high transparency. However, when the Pr 3+ content is greater than 0.06 mol%, the entry of Pr 3+ gradually destroys the high symmetry of the ceramic crystal and reduces the transparency.

[0084] Test Example 4

[0085] The transparency of the ceramic materials provided in Examples 1 to 4 and Comparative Example 1 under 10 light-heat stimulation cycles was tested using a UV-6100 ultraviolet-visible spectrophotometer, and the transparency change curve graph was plotted as Figure 4 shown. The modulation of transparency by photochromism is defined by the equation to define the modulation ratio R T the degree of influence of photochromism on transparency, and the photochromic transparency modulation ratios R T of different ceramic materials were obtained and recorded in Figure 4 . It can be seen from Figure 4 that after the introduction of Pr 3+ in Examples 1 to 4, more defects were induced to form due to lattice distortion of different ionic radii and valence states (maintaining electrical neutrality), effectively enhancing the photochromic reaction. Therefore, the R T of the examples was larger than that of Comparative Example 1; however, more defects would reduce the transparency of the ceramics. Therefore, the transparency change trend was opposite to the photochromic regulation trend, and different modulation ratios were also presented for transparency modulation.

[0086] Test Example 5

[0087] The fluorescence intensity change of the ceramic materials provided in Examples 1 to 4 before and after 407 nm light irradiation for 1 min was tested using an FS-5000 transient fluorescence spectrometer, and the fluorescence intensity curve graph was obtained as Figure 5 shown. The modulation ratio R can be defined by the equation L to represent the influence of the photochromic reaction on the fluorescence intensity, and the photochromic fluorescence modulation ratios R L of different ceramic materials were obtained and recorded in Figure 5 . It can be seen from Figure 5 that Pr 3+The introduction first improved the symmetry of the ceramic phase structure, compensated for the valence of K / Na volatilization, and achieved better symmetry at 0.06 mol%, so the photochromic regulation decreased; Pr 3+ After doping exceeds 0.06 mol%, it will destroy the high symmetry of the ceramic, which can be proved by XRD; the structure with poor symmetry will induce the formation of defects, and excessive hetero-valent Pr 3+ will lead to the formation of more defects, so the defect concentration of the ceramic increases, enhancing the photochromic reaction, and the highest photochromic modulation ratio (89.22%) is obtained at 0.1 mol%; Comparative Example 1 does not have luminescence characteristics due to the absence of rare earths.

[0088] The photochromic fluorescence modulation ratio R of the ceramic material provided in Example 4 was plotted under 10 light irradiation-thermal stimulation cycles L as shown in Figure 6 From Figure 6 it can be seen that the fluorescence intensity modulation of the transparent photochromic ceramic material provided by the present invention has reversible stability.

[0089] From the above examples, it can be seen that the transparent photochromic ceramic material provided by the present invention has good transparency and fluorescence regulation ratio at the same time.

[0090] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A transparent photochromic ceramic material, characterized in that, The transparent photochromic ceramic material is Pr6O 11 doped 0.94(K 0.5 Na 0.5 )NbO3 - 0.06(Sr 0.5 Ba 0.5 )(Zn 1 / 3 Bi 2 / 3 )O3 ceramic. In terms of mole percentage, the doping amount of Pr6O 11 in the transparent photochromic ceramic material is 0.04 - 0.1%.

2. The transparent photochromic ceramic material according to claim 1, wherein The transparent photochromic ceramic material has a pseudo-cubic phase structure of ABO3 perovskite.

3. The method for preparing the transparent photochromic ceramic material according to claim 1 or 2, comprising the following steps: (1) According to the stoichiometric ratio, mix the potassium source, sodium source, niobium source, strontium source, bismuth source, zinc source, barium source and praseodymium source, and then perform primary ball milling, pre-sintering and secondary ball milling in sequence to obtain ceramic powder; (2) Press and mold the ceramic powder obtained in the step (1), and then perform sintering to obtain the transparent photochromic ceramic material.

4. The preparation method according to claim 3, characterized in that, In the step (1), the pre-sintering temperature is 840 - 860 °C, and the pre-sintering time is 1 - 3 h.

5. The preparation method according to claim 3, characterized in that, The particle size of the ceramic powder obtained in the step (1) is ≤ 0.1 mm.

6. The preparation method according to claim 3, wherein The sintering in the step (2) includes first sintering and second sintering performed in sequence; the temperature of the first sintering is 550 - 650 °C, and the time is 120 - 180 min; the temperature of the second sintering is 1130 - 1160 °C, and the time is 180 - 240 min.

7. The preparation method according to claim 6, characterized in that, The heating rate of the first sintering is 1 - 2 °C / min; the heating rate of the second sintering is 3 - 5 °C / min.

8. The preparation method according to claim 3, characterized in that, The pressure for pressing and molding in the step (2) is 1 - 8 MPa.

9. The preparation method according to claim 3 or 8, characterized in that, Before the pressing and molding in the step (2), granulation of the ceramic powder is also included.

10. The application of the transparent photochromic ceramic material according to claim 1 or 2 or the transparent photochromic ceramic material prepared by the preparation method according to any one of claims 3 - 9 in optical fibers, solid-state lasers, optical storage, optical attenuators, smart windows or optical switches.

Images