Rare earth oxysulfide ceramic and preparation method thereof

Abstract

The invention provides a rare earth oxysulfide ceramic and a preparation method thereof, and relates to the technical field of oxysulfide ceramics. The preparation method of the rare earth oxysulfide ceramic provided by the invention comprises the following steps: S1, ball-milling and mixing an organic solvent, a dispersing agent, rare earth oxysulfide powder, a binder and a plasticizer to obtain slurry; s2, the slurry is injected into a mold, a magnetic field is applied while the slurry is injected, and a primary blank is obtained through curing, demolding and drying; s3, the initial blank is subjected to debonding and sintering, and the rare earth oxysulfide ceramic is obtained. A magnetic field is applied while grouting, and under the action of the magnetic field, grains in rare earth oxysulfide slurry rotate and are directionally arranged along the direction of the magnetic field, so that the microcosmic grain structure of the rare earth oxysulfide ceramic is textured, the birefringence and scattering phenomena of the ceramic grain boundary are reduced, and the transmittance of the material is improved; and an effective way is provided for solving the problem of low transmittance of the rare earth oxysulfide ceramic material.

Description

Technical Field

[0001] The invention relates to the technical field of oxysulfide ceramic materials, and in particular to a rare earth oxysulfide ceramic and a preparation method thereof. Background Art

[0002] Sulfur oxides have high density, high chemical stability and can be used as Pr 3+ , Tb 3+ With Eu 3+ Rare earth ions such as sulfur oxides provide a good luminescent coordination environment, and they are widely used as fluorescent or scintillating materials in lighting, displays, fiber optic communications, and X-ray imaging. However, sulfur oxides belong to the hexagonal crystal structure and exhibit significant birefringence characteristics, that is, the refractive index varies due to the different angles between the light wave and the crystal axis. Existing preparation technologies for sulfur oxide ceramics include hot pressing or powder encapsulation sintering methods. Due to the random orientation of the grains in the ceramic sintered body, this birefringence phenomenon will cause visible light to scatter at the grain boundaries, resulting in significant light energy loss, thereby greatly weakening the overall transmittance of the ceramic material. Therefore, for non-cubic ceramic materials such as rare earth sulfur oxides, improving the transmittance has become an extremely challenging technical problem. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a rare earth oxysulfide ceramic and a preparation method thereof. The prepared rare earth oxysulfide ceramic has a high transmittance.

[0004] The present invention provides a method for preparing rare earth oxysulfide ceramics, comprising the following steps: S1, an organic solvent, a dispersant, rare earth oxysulfide powder, a binder and a plasticizer are mixed by ball milling to obtain a rare earth oxysulfide slurry; S2, injecting the rare earth oxysulfide slurry described in step S1 into a mold, and applying a magnetic field while injecting the rare earth oxysulfide slurry to arrange the rare earth oxysulfide particles in the rare earth oxysulfide slurry in a specific direction, and then curing, demolding, and drying to obtain a preform; S3. The rough blank described in step S2 is debonded and sintered to obtain rare earth oxysulfide ceramics.

[0005] The present invention applies a magnetic field while grouting, utilizing the property of rare earth elements having a large magnetic moment. Under the action of the magnetic field, the grains in the rare earth oxysulfide slurry rotate and orient along the direction of the magnetic field, so that the microscopic grain structure of the rare earth oxysulfide ceramic is textured, thereby reducing the birefringence and scattering phenomena of the ceramic grain boundaries, thereby improving the transmittance of the material, and providing an effective way to solve the problem of low transmittance of rare earth oxysulfide ceramic materials.

[0006] In a possible implementation, the general formula of the rare earth sulfur oxide in the rare earth sulfur oxide powder in step S1 is (Re 1-x , Re’ x )2O2S, where Re is used as the matrix atom, Re’ is the luminescent ion, Re is at least one of the rare earth elements La, Gd, Y, and Lu, Re’ is at least one of Pr, Tb, and Eu, and 0 < x ≤ 0.2.

[0007] In a possible implementation, the mass ratio of the rare earth sulfur oxide powder in the rare earth sulfur oxide slurry in step S1 is 30 wt.% to 70 wt.%, the mass ratio of the dispersant is 0.1 wt.% to 3.0 wt.%, the mass ratio of the binder is 5 wt.% to 20 wt.%, the mass ratio of the plasticizer is 2.5 wt.% to 10 wt.%, and the balance is the organic solvent.

[0008] In a possible implementation, the organic solvent in step S1 is at least one of methanol, ethanol, isopropanol, acetone, methyl butyl ketone, and diethyl ether.

[0009] In a possible implementation, the dispersant in step S1 is at least one of polyacrylate, polyvinylpyrrolidone, polyethylene glycol, and polyacrylamide.

[0010] In a possible implementation, the binder in step S1 is at least one of polyvinyl butyral, polyvinyl alcohol, sodium carboxymethyl cellulose, polyacrylic acid, methyl cellulose, and hydroxyethyl cellulose.

[0011] In a possible implementation, the plasticizer in step S1 is at least one of butyl benzyl phthalate, dibutyl phthalate, dioctyl phthalate, and diisobutyl phthalate.

[0012] In a possible implementation, the particle size of the rare earth sulfur oxide powder in step S1 is 0.01μm < R ≤ 100μm. By controlling the particle size of the rare earth sulfur oxide powder, it is ensured that the powder has excellent sintering activity, and at the same time, it can have good rotational flexibility and responsiveness under the action of an external magnetic field, perfectly meeting the strict requirements of the microstructure texture of the ceramic sintered body, and further improving the performance and quality of the overall material.

[0013] In a possible implementation, the rare earth sulfur oxide powder in step S1 has a complete grain structure. A well-developed grain structure can make the grains show a low degree of interconnection, thereby improving the high purity and excellent dispersibility of the powder.

[0014] In a possible implementation manner, the mold in step S2 is a porous mold.

[0015] Furthermore, the porous mold is made of any one of gypsum, porous resin and quartz sand. Gypsum, porous resin and quartz sand have excellent molding performance and structural stability, which are convenient for the preparation and stable use of the mold.

[0016] In a possible implementation, the strength of the magnetic field in step S2 is 0.01 T to 30 T. The magnetic field strength is controlled within the range of 0.01 T to 30 T, which can balance the magnetic field assisting effect and avoid energy waste.

[0017] In a possible implementation, the angle between the direction of the magnetic field in step S2 and the flow direction of the slurry is 0° to 180°. When the angle between the direction of the magnetic field and the flow direction of the slurry is 0° to 180°, the best magnetic field auxiliary effect can be obtained.

[0018] In a possible implementation, the demoulding method in step S2 is non-contact demoulding or low-stress demoulding. The non-contact or low-stress demoulding technology can be used to gently and quickly separate the green body from the mold to avoid any form of damage to the green body.

[0019] In a possible implementation, the drying temperature in step S2 is 50° C. to 120° C. By controlling the drying temperature, the organic solvent remaining in the green body can be evenly removed, thereby avoiding subsequent cracking or deformation of the green body.

[0020] In one possible implementation, the heating rate of the debonding in step S3 is 0.5°C / min to 5°C / min, and the holding time is 1 h to 20 h. By controlling the heating rate and holding time of the debonding, the residual organic solvent in the green body can be completely removed, which is conducive to forming a dense ceramic body.

[0021] In a possible implementation manner, the sintering temperature in step S3 is 1150° C. to 1500° C.

[0022] In a possible implementation manner, the sintering atmosphere in step S3 is a vacuum or weak reducing atmosphere.

[0023] By precisely controlling the sintering temperature and sintering atmosphere, the prepared rare earth oxysulfide ceramics can have high density and ideal crystal structure. The invention also provides rare earth oxysulfide ceramics prepared by the method.

[0024] Based on the common knowledge in this field, the above-mentioned implementation modes can be combined arbitrarily.

[0025] The reagents and raw materials used in the present invention are commercially available.

[0026] The positive and progressive effects of the present invention are: The present invention provides a method for preparing rare earth oxysulfide ceramics, which uses a strong magnetic field to achieve directional arrangement of grains in rare earth oxysulfide slurry. Given that rare earth elements have a large magnetic moment and their electronic structure may produce magnetic anisotropy, by applying a strong magnetic field during the grouting process, the grains in the slurry can be rotated and arranged in an orderly manner along the direction of the magnetic field, thereby achieving texturing of the ceramic micro-grain structure. This method is conducive to reducing the birefringence and scattering phenomena of the ceramic grain boundaries, thereby improving the transmittance of the material, and provides an effective way to solve the problem of low transmittance of rare earth oxysulfide ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the praseodymium-doped gadolinium oxysulfide powder prepared in Example 1.

[0028] Figure 2 Schematic diagram of the microstructure of the rare earth oxysulfide ceramic prepared in Example 1.

[0029] Figure 3 Schematic diagram of the microstructure of the rare earth oxysulfide ceramic prepared in Comparative Example 1. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0031] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0032] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which this invention pertains. In some cases, for purposes of clarification or facilitation of reference, terms with conventional understood meanings are defined herein, and such definitions herein should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments is carried out in accordance with the protocols and parameters provided by the manufacturers.

[0033] Example 1

[0034] This example provides a rare earth sulfur oxide ceramic with a chemical composition of (Gd 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: Powder preparation: Weigh 47.8344 g of gadolinium oxide, 0.0450 g of praseodymium oxide, 16.8905 g of sulfur powder, 0.5 g of sodium carbonate, 200 g of zirconia grinding balls, and 13 mL of anhydrous ethanol and add them to a ball mill jar. Then use a planetary ball mill to mix them evenly. The rotation speed of the ball mill is 80 r / min, and the ball milling time is 11 h. After ball milling, separate the slurry from the grinding balls and dry it in an oven at 80 °C for 10 h to ensure complete drying. After the powder is completely dry, grind it with a mortar and pass it through a 200-mesh sieve. Then load the sieved powder into an alumina crucible and place it in a corundum tube furnace for calcination. The calcination temperature is 1150 °C, and the calcination time is 4 h. After the powder is calcined and cooled, grind it again with a mortar and pass it through a 200-mesh sieve. To remove any possible residual small amounts of unreacted oxide raw materials and impurities in the powder, perform acid washing on the sieved powder. Subsequently, wash it multiple times with deionized water until the washing liquid is neutral. Finally, place the washed powder in an oven to dry until all the moisture is completely removed, thereby obtaining high-purity (Gd 0.999 , Pr 0.001 )2O2S powder. The particle size range of the powder is 0.01 μm < R ≤ 100 μm, and the microstructure of the powder is as shown in Figure 1 . As can be seen from the figure, the powder has a complete grain structure; Slurry preparation: Measure 15 mL of anhydrous ethanol and add it to a ball mill jar. Weigh 1.5 g of polyvinylpyrrolidone and 200 g of zirconia balls and add them to the ball mill jar together. Close the lid of the ball mill jar and start the planetary ball mill to fully dissolve the polyvinylpyrrolidone in the ethanol. This process is accompanied by the preliminary stirring action of the ball mill. After the polyvinylpyrrolidone is dissolved, weigh 50 g of (Gd 0.999 , Pr 0.001)2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h; then 5 g of polyvinyl butyral and 7.5 g of toluyl butyl phthalate were added to the ball mill respectively; then, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed into a slurry with the desired properties; Casting: Pour the prepared slurry into the plaster mold, pay attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry; for large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold; a 9T magnetic field is loaded parallel to the pouring direction of the slurry; after the slurry is completely solidified, the green body is removed from the mold by a low-stress demoulding method, and the demoulded green body is immediately transferred to an oven for drying at a temperature of 80°C; Debonding: Place the cast green body in a muffle furnace for debonding, with a heating rate of 1 °C / min, a debonding temperature of 550 °C, and keep it warm for 5 h; Ceramic sintering: The debonded green body is re-sealed and cold isostatically pressed at 200 MPa to make the body more compact. It is then sintered in a vacuum furnace. The sintering temperature is 1450 °C and the holding time is 2 h. After sintering, the microstructure of the ceramic is as shown in the figure. Figure 2 It can be seen that the ceramic grain orientation is obvious in the casting molding assisted by the magnetic field. After the ceramic is thinned to 1 mm and double-sided polished, the total transmittance of the ceramic at 513 nm is 39%.

[0035] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no magnetic field is applied during the pouring process. Figure 3 , casting without magnetic field assistance, ceramic grains have no obvious orientation. After the ceramic is thinned to 1 mm thick and double-sided polished, the total transmittance of the ceramic at 513 nm is 31%.

[0036] Example 2

[0037] This embodiment provides a rare earth oxysulfide ceramic, the chemical composition of which is (La 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: (1) Powder preparation: Weigh 47.6022 g of lanthanum oxide, 0.0498 g of praseodymium oxide, 18.7019 g of sulfur powder, 0.5 g of sodium carbonate, 200 g of zirconium oxide grinding balls, and 14 mL of anhydrous ethanol respectively and add them into a ball mill. Then, mix them evenly using a planetary ball mill at a speed of 80 r / min for 11 h. After ball milling, separate the slurry from the grinding balls and dry them in an oven at 80 °C for 10 h to ensure complete drying. After the powder is completely dry, grind it with a mortar and pass it through a 200-mesh sieve. Then, put the sieved powder into an alumina crucible and place it in a corundum tube furnace for calcination at a temperature of 1150 °C for 4 h; after the powder is calcined and cooled, it is ground again with a mortar and sieved through a 200-mesh sieve; in order to remove a small amount of unreacted oxide raw materials and impurities that may remain in the powder, the sieved powder is acid-washed; then, it is washed with deionized water for multiple times until the washing liquid is neutral; finally, the washed powder is placed in an oven to dry until the water is completely removed, thereby obtaining high-purity (La 0.999 , Pr 0.001 )2O2S powder, the powder has a complete grain structure, and the particle size range of the powder is 0.01 μm <R≤ 100 μm; (2) Slurry preparation: Measure 15 mL of anhydrous ethanol and add it to a ball mill. Weigh 1.5 g of polyvinyl pyrrolidone and 200 g of zirconium oxide balls and add them to the ball mill. Close the cover of the ball mill and start the planetary ball mill to fully dissolve the polyvinyl pyrrolidone in the ethanol. This process is accompanied by the initial stirring of the ball mill. After the polyvinyl pyrrolidone is dissolved, weigh 50 g (La 0.999 , Pr 0.001 )2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h. Then, 5 g of polyvinyl butyral and 7.5 g of toluyl butyl phthalate were added to the ball mill respectively. Subsequently, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed a slurry with the required properties. The drying temperature was 80 °C. (3) Casting: Pour the prepared slurry into the plaster mold, and pay attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry. For large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold. A 9T magnetic field is applied parallel to the pouring direction of the slurry. After the slurry is completely solidified, the green body is removed from the mold using a low-stress demolding method. The demolded green body is then transferred to an oven for drying. (4) Debonding: The cast green body is placed in a muffle furnace for debonding at a heating rate of 1 °C / min and a debonding temperature of 550 °C, and kept at this temperature for 5 h; (5) Ceramic sintering: The debonded green blank is re-sealed and cold isostatically pressed at 200 MPa to make the blank more compact, and then sintered in a vacuum furnace. The sintering temperature is 1450 °C and the holding time is 2 h. After the ceramic is thinned to 1 mm and double-sided polished, the total transmittance of the ceramic at 513 nm is 42%.

[0038] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that no magnetic field is applied during the casting process. After the ceramic is thinned to 1 mm thick and double-sided polished, the total transmittance of the ceramic at 513 nm is 33%.

[0039] Example 3

[0040] This embodiment provides a rare earth oxysulfide ceramic, the chemical composition of which is (Lu 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: (1) Powder preparation: Weigh 48.0196 g of lutetium oxide, 0.0411 g of praseodymium oxide, 15.4458 g of sulfur powder, 0.5 g of sodium carbonate, 200 g of zirconium oxide grinding balls, and 13 mL of anhydrous ethanol respectively and add them into a ball mill. Then, mix them evenly using a planetary ball mill. The speed of the ball mill is 80 r / min and the ball milling time is 11 h. After ball milling, separate the slurry from the grinding balls and dry them in an oven at 80 °C for 10 h to ensure complete drying. After the powder is completely dry, grind it in a mortar and pass it through a 200-mesh sieve. Then, put the sieved powder into an alumina crucible and place it in a corundum tube furnace for calcination at a temperature of 1150 °C and a calcination time of 4 h; after the powder is calcined and cooled, it is ground again with a mortar and passed through a 200-mesh sieve; in order to remove a small amount of unreacted oxide raw materials and impurities that may remain in the powder, the sieved powder is acid-washed; then, it is washed with deionized water for multiple times until the washing liquid is neutral; finally, the washed powder is placed in an oven to dry until the water is completely removed, thereby obtaining high-purity (Lu 0.999 , Pr 0.001 )2O2S powder, the powder has a complete grain structure, and the particle size range of the powder is 0.01 μm <R≤ 100 μm; (2) Slurry preparation: 15 mL of anhydrous ethanol was added to a ball mill, and 1.5 g of polyvinyl pyrrolidone and 200 g of zirconium oxide balls were weighed and added to the ball mill. The ball mill cover was closed and the planetary ball mill was started to fully dissolve the polyvinyl pyrrolidone in the ethanol. This process was accompanied by the initial stirring of the ball mill. After the polyvinyl pyrrolidone was dissolved, 50 g (Lu 0.999 , Pr 0.001 )2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h. Then, 5 g of polyvinyl butyral and 7.5 g of toluyl butyl phthalate were added to the ball mill respectively. Subsequently, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed into a slurry with the desired properties. (3) Casting: Pour the prepared slurry into the plaster mold, paying attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry; for large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold; a 9T magnetic field is loaded parallel to the pouring direction of the slurry; after the slurry is completely solidified, the green body is removed from the mold by a low-stress demoulding method, and the demoulding green body is then transferred to an oven for drying at a temperature of 80 °C; (4) Debonding: The cast green body is placed in a muffle furnace for debonding at a heating rate of 1 °C / min and a debonding temperature of 550 °C, and kept at this temperature for 5 h; (5) Ceramic sintering: The debonded green blank is re-sealed and cold isostatically pressed at 200 MPa to make the blank more compact. It is then sintered in a vacuum furnace. The sintering temperature is 1450 °C and the holding time is 2 h. After the ceramic is thinned to 1 mm and double-sided polished, the total transmittance of the ceramic at 513 nm is 26%.

[0041] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that no magnetic field is applied during the casting process. After the ceramic is thinned to 1 mm thick and double-sided polished, the total transmittance of the ceramic at 513 nm is 20%.

[0042] Example 4

[0043] This embodiment provides a rare earth oxysulfide ceramic, the chemical composition of which is (Y 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: (1) Powder preparation: Weigh 46.6125 g of yttrium oxide, 0.0703 g of praseodymium oxide, 26.4210 g of sulfur powder, 0.5 g of sodium carbonate, 200 g of zirconium oxide grinding balls, and 13 mL of anhydrous ethanol respectively and add them into a ball mill. Then, mix them evenly using a planetary ball mill. The speed of the ball mill is 80 r / min and the ball milling time is 11 h. After ball milling, separate the slurry from the grinding balls and dry them in an oven at 80 °C for 10 h to ensure complete drying. After the powder is completely dry, grind it with a mortar and pass it through a 200-mesh sieve. Then, put the sieved powder into an alumina crucible and place it in a corundum tube furnace for calcination at a temperature of 1150 °C and a calcination time of 4 h; after the powder is calcined and cooled, it is ground again with a mortar and passed through a 200-mesh sieve; in order to remove a small amount of unreacted oxide raw materials and impurities that may remain in the powder, the sieved powder is acid-washed; then, it is washed with deionized water for multiple times until the washing liquid is neutral; finally, the washed powder is placed in an oven to dry until the water is completely removed, thereby obtaining high-purity (Y 0.999 , Pr 0.001 )2O2S powder, the powder has a complete grain structure, and the particle size range of the powder is 0.01 μm <R ≤100 μm; (2) Slurry preparation: Measure 15 mL of anhydrous ethanol and add it to a ball mill. Weigh 1.5 g of polyvinyl pyrrolidone and 200 g of zirconium oxide balls and add them to the ball mill. Close the cover of the ball mill and start the planetary ball mill to fully dissolve the polyvinyl pyrrolidone in the ethanol. This process is accompanied by the initial stirring of the ball mill. After the polyvinyl pyrrolidone is dissolved, weigh 50 g (Y 0.999 , Pr 0.001 )2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h. Then, 5 g of polyvinyl butyral and 7.5 g of toluyl butyl phthalate were added to the ball mill respectively. Subsequently, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed into a slurry with the desired properties. (3) Casting: Pour the prepared slurry into the plaster mold, paying attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry; for large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold; a 9T magnetic field is loaded parallel to the pouring direction of the slurry; after the slurry is completely solidified, the green body is removed from the mold by a low-stress demoulding method, and the demoulding green body is then transferred to an oven for drying at a temperature of 80 °C; (4) Debonding: Place the cast green body in a muffle furnace for debonding at a heating rate of 1 °C / min, a debonding temperature of 550 °C, and keep it at this temperature for 5 h; (5) Ceramic sintering: The debonded green body is re-sealed and cold isostatically pressed at 200 MPa to make the body more compact. It is then sintered in a vacuum furnace at a sintering temperature of 1450 °C for 2 h. After the ceramic is thinned to 1 mm and double-sided polished, the total transmittance of the ceramic at 513 nm is 29%.

[0044] Comparative Example 4 The difference between Comparative Example 4 and Example 4 is that no magnetic field is applied during the casting process. After the ceramic is thinned to 1 mm thick and double-sided polished, the total transmittance of the ceramic at 513 nm is 23%.

[0045] Example 5

[0046] This embodiment provides a rare earth oxysulfide ceramic, the chemical composition of which is (Gd 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: (1) Slurry preparation: 15 mL of isopropanol was added to a ball mill, and 1.5 g of polyacrylate and 200 g of zirconia balls were weighed and added to the ball mill. The lid of the ball mill was closed and the planetary ball mill was started to fully dissolve the polyacrylate in the isopropanol. This process was accompanied by the initial stirring of the ball mill. After the polyacrylate was dissolved, 50 g (Gd 0.8 , Pr 0.2 )2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h. Then, 5 g of polyvinyl alcohol and 7.5 g of butyl benzyl phthalate were added to the ball mill respectively. Subsequently, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed into a slurry with the desired properties. (2) Casting: Pour the prepared slurry into a porous resin mold, paying attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry. For large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold. Apply a 0.5 T magnetic field, with the angle between the direction of the magnetic field and the flow direction of the slurry being 0°. After the slurry is completely solidified, remove the green body from the mold using a low-stress demolding method. The demolded green body is then transferred to an oven for drying at a temperature of 50 °C. (3) Debonding: The cast green body is placed in a muffle furnace for debonding at a heating rate of 0.5 °C / min, a debonding temperature of 550 °C, and kept at this temperature for 1 h. (4) Ceramic sintering: The debonded green body is re-sealed and subjected to cold isostatic pressing at 200 MPa to make the body denser. It is then sintered in a vacuum furnace at a sintering temperature of 1150 °C for 2 h. The ceramic is thinned to 1 mm thick and double-sided polished. The total transmittance of the ceramic at 513 nm is 39%.

[0047] Example 6

[0048] This embodiment provides a rare earth oxysulfide ceramic, the chemical composition of which is (Y 0.999 , Pr 0.001 )2O2S, which is prepared by the following method: (1) Slurry preparation: 15 mL of ether was added to a ball mill, and 1.5 g of polyethylene glycol and 200 g of zirconium oxide balls were weighed and added to the ball mill. The cover of the ball mill was closed and the planetary ball mill was started to fully dissolve the polyethylene glycol in the ether. This process was accompanied by the initial stirring of the ball mill. After the polyethylene glycol was dissolved, 50 g (Y 0.9 , Pr 0.1 )2O2S powder was added to the ball mill and continued to be ball milled on a planetary ball mill at a speed of 400 rpm for 5 h. Then, 5 g of sodium carboxymethyl cellulose and 7.5 g of dioctyl phthalate were added to the ball mill respectively. Subsequently, the ball milling was continued at the same speed (400 rpm) and the ball milling time was extended to a total of 10 h to ensure that all components were fully mixed and uniformly formed into a slurry with the desired properties. (2) Casting: Pour the prepared slurry into a quartz sand mold, paying attention to controlling the pouring speed and flow rate to avoid bubbles or splashing of the slurry. For large or complex-shaped products, multiple pouring or local pressurization can be used to ensure that the slurry fills every corner of the mold. Apply a 30 T magnetic field, with the angle between the direction of the magnetic field and the flow direction of the slurry being 180°. After the slurry is completely solidified, remove the green body from the mold using a non-contact demolding method. The demolded green body is then transferred to an oven for drying at a temperature of 120 °C. (3) Debonding: Place the cast green body in a muffle furnace for debonding at a heating rate of 5 °C / min, a debonding temperature of 550 °C, and keep it at this temperature for 20 h; (4) Ceramic sintering: The debonded green body is re-sealed and cold isostatically pressed at 200 MPa to make the body more compact. It is then sintered in a vacuum furnace at a sintering temperature of 1500 °C for 2 h. After the ceramic is thinned to 1 mm and double-sided polished, the total transmittance of the ceramic at 513 nm is 29%.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing rare earth oxysulfide ceramics, characterized in that: The following steps are involved: S1, an organic solvent, a dispersant, rare earth oxysulfide powder, a binder and a plasticizer are mixed by ball milling to obtain a rare earth oxysulfide slurry; S2, injecting the rare earth oxysulfide slurry described in step S1 into a mold, and applying a magnetic field while injecting the rare earth oxysulfide slurry to arrange the rare earth oxysulfide particles in the rare earth oxysulfide slurry in a specific direction, and then curing, demolding, and drying to obtain a preform; S3. The rough blank described in step S2 is debonded and sintered to obtain rare earth oxysulfide ceramics.

2. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The general formula of the rare earth sulfur oxide in the rare earth sulfur oxide powder in step S1 is (Re 1-x , Re' x )2O2S, wherein Re is used as a matrix atom, Re' is used as a luminescent ion, Re is at least one of the rare earth elements La, Gd, Y and Lu, and Re' is at least one of Pr, Tb and Eu, 0 <x≤0.2。 3. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: In the rare earth oxysulfide slurry of step S1, the mass proportion of the rare earth oxysulfide powder is 30 wt.% ~ 70 wt.%, the mass proportion of the dispersant is 0.1 wt.% ~ 3.0 wt.%, the mass proportion of the binder is 5 wt.% ~ 20 wt.%, the mass proportion of the plasticizer is 2.5 wt.% ~ 10 wt.%, and the balance is the organic solvent.

4. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The organic solvent in step S1 is at least one of methanol, ethanol, isopropanol, acetone, methyl butyl ketone and ether; And / or, the dispersant in step S1 is at least one of polyacrylate, polyvinyl pyrrolidone, polyethylene glycol and polyacrylamide; And / or, the binder in step S1 is at least one of polyvinyl butyral, polyvinyl alcohol, sodium carboxymethyl cellulose, polyacrylic acid, methyl cellulose and hydroxyethyl cellulose; And / or, the plasticizer in step S1 is at least one of butyl benzyl phthalate, dioctyl phthalate and diisobutyl phthalate; And / or, the particle size of the rare earth oxysulfide powder in step S1 is 0.01 μm < R ≤ 100 μm; And / or, the rare earth oxysulfide powder in step S1 has a complete grain structure.

5. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The mold in step S2 is a porous mold; And / or, the drying temperature in step S2 is 50°C to 120°C.

6. The method for preparing rare earth oxysulfide ceramics according to claim 5, characterized in that: The material of the porous mold is any one of gypsum, porous resin and quartz sand.

7. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The intensity of the magnetic field in step S2 is 0.01T ~ 30T; And / or, the angle between the direction of the magnetic field in step S2 and the flow direction of the slurry is 0° to 180°; And / or, the demoulding method in step S2 is non-contact demoulding or low-stress demoulding.

8. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The debonding process in step S3 has a heating rate of 0.5°C / min to 5°C / min and a holding time of 1 h to 20 h.

9. The method for preparing rare earth oxysulfide ceramics according to claim 1, characterized in that: The sintering temperature in step S3 is 1150°C to 1500°C; And / or, the sintering atmosphere in step S3 is a vacuum or weak reducing atmosphere.

10. A rare earth oxysulfide ceramic, characterized in that: The rare earth oxysulfide ceramic is prepared by the rare earth oxysulfide ceramic preparation method according to any one of claims 1 to 9.

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