High-purity ultrafine-grained yttrium aluminum garnet ceramic powder and method for preparing same

Abstract

The application discloses a kind of high-purity ultrafine grain yttrium aluminum garnet ceramic powder and preparation method thereof, it is related to ceramic powder technical field.The application uses aluminium source powder and yttrium source powder as raw material, first configuration mixed homogeneous slurry, then to homogeneous slurry is washed, filter pressing, drying, again by calcination obtains high specific surface, high dispersion, high-purity gamma-Al2O3 / Y2O3 Powder;Then ultraviolet irradiation treatment is carried out after adding dispersing agent, inducer to gamma-Al2O3 / Y2O3 Powder, then carries out stage calcination, and high-purity ultrafine grain yttrium aluminum garnet ceramic powder is prepared.The grain size of high-purity ultrafine grain yttrium aluminum garnet ceramic powder prepared by the application is 20-200 nm, and grain size distribution is uniform;The grain of powder is weakly combined, and it is extremely easy to break;The purity of powder is higher than 99.9 %, and YAG phase content is higher than 95 %.

Description

Technical Field

[0001] This invention relates to the field of ceramic powder technology, and in particular to a high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder and its preparation method. Background Technology

[0002] Yttrium aluminum garnet (Y3Al5O) 12 YAG (yellow alumina) is widely used in many fields due to its good chemical stability, high-temperature mechanical properties, excellent optical uniformity, and lack of birefringence, especially in laser and optics, semiconductor manufacturing, transparent protection, and materials for extreme environments.

[0003] Because the luminescence properties of phosphors and the transmittance properties of transparent materials are highly sensitive to the purity, grain size, and YAG phase content of yttrium aluminum garnet (YAG) ceramic powders, synthesizing YAG powders with high purity, ultrafine particle size, and good dispersibility is fundamental to the preparation of high-performance materials. Currently, methods for synthesizing YAG ceramic powders include solid-state synthesis, co-precipitation, sol-gel, polymer network gel, eutectic, and mechanochemical methods. Among these, solid-state synthesis is simple and efficient, facilitating large-scale production, and has become the most widely used and technologically mature process. However, during the solid-state synthesis reaction, intermediate phases YAM (Y4Al2O9) and YAP (YAlO3) are easily generated, requiring secondary grinding or prolonged high-temperature calcination to eliminate them. Furthermore, the synthesized ceramic powders have large particles (micrometer-sized), severe agglomeration, and low sintering activity.

[0004] In the prior art, CN118908712A discloses a method for preparing yttrium aluminum garnet ceramic powder by stirring yttrium oxide powder, alumina powder, deionized water, dispersants (citric acid, sodium hexametaphosphate, etc.), and binders, followed by spray granulation and calcination at 1000-1600 ℃. Although the yttrium aluminum garnet ceramic powder prepared by the method in this patent has a concentrated particle size distribution, its preparation process only focuses on the particle size of the yttrium aluminum garnet powder and the low-temperature synthesis of the YAG phase, without paying attention to the grain size of the synthesized powder. Only fine-grained, high-purity powder can be used to prepare high-performance, high-density YAG ceramics.

[0005] Therefore, a simple solid-state synthesis method for yttrium aluminum garnet ceramic powder is needed, which can synthesize high-purity yttrium aluminum garnet ceramic powder with ultrafine grain size at a relatively low temperature. Summary of the Invention

[0006] To address the aforementioned limitations of existing technologies, the present invention aims to provide a high-purity, ultrafine-grained yttrium aluminum garnet (YAG) ceramic powder and its preparation method. This invention uses aluminum source powder and yttrium source powder as raw materials. First, a uniformly mixed slurry is obtained according to a specified ratio. Then, the uniform slurry is washed, filtered, and dried, followed by calcination to obtain a high-specific-surface-area, highly dispersed, and high-purity γ-Al₂O₃ / Y₂O₃ powder. Next, a dispersant and an initiator are added to the γ-Al₂O₃ / Y₂O₃ powder, followed by ultraviolet irradiation treatment and staged calcination to obtain the high-purity, ultrafine-grained YAG ceramic powder. The high-purity, ultrafine-grained YAG ceramic powder obtained by this invention has a grain size of 20-200 nm and a uniform grain size distribution. The grain bonding of the powder is weak, making it easily broken. The purity of the powder is higher than 99.9%, and the YAG phase content is higher than 95%.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder, comprising the following steps:

[0009] (1) Aluminum source powder, yttrium source powder and deionized water are mixed in proportion to obtain a uniform slurry; the uniform slurry is washed, filtered and dried, and then calcined at low temperature to obtain γ-Al2O3 / Y2O3 powder;

[0010] (2) Mix γ-Al2O3 / Y2O3 powder, dispersant, initiator and water in proportion to obtain composite uniform slurry; dry and crush the composite uniform slurry and then treat it with ultraviolet irradiation, and then perform medium-temperature calcination and high-temperature calcination in sequence to obtain high-purity ultrafine grain yttrium aluminum garnet ceramic powder.

[0011] Preferably, in step (1), the aluminum source powder is one or more of Al(OH)3, α / γ-AlOOH, and metastable Al2O3, with a purity > 99.8%; the yttrium source powder is one or more of Y2O3, Y(CH3COO)3, and Y(OH)3, with a purity > 99.8%.

[0012] Furthermore, metastable Al2O3 includes one or more mixtures of amorphous Al2O3, γ-Al2O3, θ-Al2O3, δ-Al2O3, etc.

[0013] Preferably, in step (1), the aluminum source powder can be obtained by mixing one or more of aluminum chloride, aluminum sulfate, aluminum carbonate, ammonium aluminum sulfate, ammonium aluminum carbonate, and aluminum alkoxides (e.g., aluminum isopropoxide) via a liquid phase method such as hydrothermal method, sol-gel method, or precipitation method, and / or by calcination at 200-700 ℃; the yttrium source powder can be obtained by mixing one or more of yttrium chloride, yttrium sulfate, yttrium nitrate, yttrium acetate, and yttrium carbonate via a liquid phase method such as hydrothermal method, sol-gel method, or precipitation method, and / or by calcination at 200-700 ℃.

[0014] Preferably, in step (1), the total mass ratio of aluminum source powder and yttrium source powder to deionized water is 1:(0.5-8).

[0015] Preferably, in step (1), the amount of aluminum source powder and yttrium source powder is determined based on the molar ratio of Y2O3 to Al2O3 in the final high-purity ultrafine grain yttrium aluminum garnet ceramic powder being 3:5, that is, the molar ratio of Al element in aluminum source powder and Y element in yttrium source powder is controlled to be 10:6.

[0016] Preferably, in step (1), the pressure is 0.1-4.5 MPa and the pore size is 0.01-0.8 μm.

[0017] As a preferred option, in step (1), the specific washing operation is as follows: first, a combination of acid washing and water washing is used to wash 2-5 times, and then ion exchange resin is used to wash 1-3 times.

[0018] Preferably, in step (1), the drying temperature is 50-90 ℃ and the drying time is 1-12 h.

[0019] As a preferred option, in step (1), the specific steps of low-temperature calcination are as follows: heating to 300-600 ℃ at a heating rate of 1-200 ℃ / min, holding for 1-4 h, then cooling to 100-200 ℃ at a cooling rate of 5-100 ℃ / min, and then furnace cooling to room temperature.

[0020] Preferably, in step (1), when γ-Al2O3 is used as the aluminum source powder, low-temperature calcination is not required.

[0021] Preferably, in step (2), the dispersant is a mixture of polyacrylamide and polyethylene glycol in a mass ratio of 1:(0.1-1.4).

[0022] Preferably, in step (2), the initiator is a mixture of seed crystals and mineralizer in a mass ratio of 1:(0.1-1), wherein the seed crystals are one or more of YAG, YAP, and YAM; and the mineralizers are one or more of AlF3, LiF, NH4F, H3BO3, B2O3, and AlCl3.

[0023] Among these methods, initiators can lower the calcination temperature, regulate the grain morphology of the powder, and remove some impurities. Specifically, seed crystals guide crystal nucleation and growth direction through a template effect, while mineralizers accelerate phase transformation by breaking chemical bonds or promoting ion migration. The synergy of both allows for precise control of crystal form and particle size: the mineralizer lowers the nucleation energy barrier, and the seed crystal provides heterogeneous nucleation sites, thereby reducing defects and increasing crystallinity. During the calcination of γ-Al₂O₃ / Y₂O₃, the mineralizer and seed crystal are used together to regulate particle morphology and sintering activity. The use of dispersants can improve the dispersibility of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder and prevent agglomeration.

[0024] Preferably, in step (2), the mass ratio of γ-Al2O3 / Y2O3 powder, dispersant, initiator and water is 1:(0.001-0.1):(0.001-0.1):(0.5-8).

[0025] Preferably, in step (2), the ultraviolet irradiation time is 0.5-10 h.

[0026] When γ-Al₂O₃ / Y₂O₃ composite powder is irradiated with ultraviolet light, γ-Al₂O₃ will form on the surface of Y₂O₃. 3+ -O 2- The active pair causes the Al-O bond in γ-Al₂O₃ to break, forming Al₂O₃. 3+ Defect sites not only increase the specific surface area but also enhance its activity, making it easier for the powder to undergo phase transformation after irradiation.

[0027] As a preferred option, in step (2), the specific operation of medium-temperature calcination is as follows: heat up to 900-1200 ℃ at a heating rate of 5-100 ℃ / min and hold for 1-5 h.

[0028] As a preferred option, in step (2), the specific operation of high-temperature calcination is as follows: heat up to 1250-1500℃ at a heating rate of 1-50℃ / min and hold for 1-5 h, then cool down to 700-900℃ at a cooling rate of 5-100℃ / min, and then furnace cool to room temperature.

[0029] Principle Analysis: During the process of medium-temperature calcination followed by high-temperature calcination of the γ-Al₂O₃ / Y₂O₃ composite powder, the temperature is first increased to 900-1200 °C at a rate of 5-100 °C / min and held for 1-5 h to promote the large-scale formation of YAP and YAM phases from γ-Al₂O₃ / Y₂O₃. Then, the temperature is increased to 1250-1500 °C at a rate of 1-50 °C / min and held for 1-5 h to promote the formation of YAG phase from YAP and YAM phases. This process compensates for the low YAG phase content in powders synthesized via conventional methods, which contain a large amount of YAP and YAM phases that have undergone phase transformation.

[0030] The specific equation is as follows:

[0031] Y2O3+ Al2O3→ 2YAlO3 (YAM, 900-1100 ℃);

[0032] 2YAlO3+ Al2O3→ Y2Al5O9 (YAP, 1100-1200 ℃);

[0033] 3Y2Al5O9 + 5Al2O3 → 2Y3Al5O 12 (YAG, 1200-1600 ℃).

[0034] As a preferred option, aluminum-rich or yttrium-rich methods are used to treat high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder to meet the needs of different fields.

[0035] Furthermore, a yttrium-enriched method was used to achieve a molar ratio of Y2O3 to Al2O3 of 1:(1.36-1.66) in the final high-purity ultrafine-grained yttrium aluminum garnet ceramic powder, in order to improve the luminous efficiency and thermal stability of the phosphor, control the doping concentration of the laser crystal, and promote the densification of transparent ceramics.

[0036] The use of aluminum-rich methods ensures that the molar ratio of Y2O3 to Al2O3 in the final high-purity ultrafine-grained yttrium aluminum garnet ceramic powder is 1:(1.67-1.97), thereby enhancing the mechanical strength and corrosion resistance of the material, optimizing the phosphor coordinates, reducing the synthesis temperature, and suppressing the formation of the intermediate phase.

[0037] In a second aspect, the present invention provides high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared by the above-described preparation method.

[0038] Preferably, the high-purity ultrafine-grained yttrium aluminum garnet ceramic powder has a grain size of 20-200 nm, a purity of >99.9%, and a YAG phase content of >95%.

[0039] A third aspect of the present invention provides the application of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder in the preparation of transparent laser ceramics, scintillator ceramics, and fluorescence conversion materials.

[0040] As a preferred option, when using high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder to prepare transparent laser ceramics and scintillator ceramics, granulation treatment is required. The specific operation of granulation treatment is as follows:

[0041] High-purity, ultrafine-grained yttrium aluminum garnet ceramic powder is pulverized and mixed with a dispersant and deionized water / ultrapure water to obtain a uniform YAG slurry; the uniform YAG slurry is then spray-dried to obtain granulated YAG powder.

[0042] Furthermore, the dispersant is a mixture of polyacrylamide and polyethylene glycol in a mass ratio of 1:(0.1-1.4); the mass ratio of high-purity ultrafine yttrium aluminum garnet ceramic powder, dispersant, and water is 1:(0-0.01):(0.5-8); the spray drying method is centrifugal atomization, pressure atomization, or airflow atomization.

[0043] The beneficial effects of this invention are:

[0044] 1. This invention uses aluminum source powder and yttrium source powder as raw materials. First, a uniformly mixed slurry is obtained in a certain proportion. Then, the uniform slurry is washed, filtered, and dried. After calcination, γ-Al2O3 / Y2O3 powder with high specific surface area, high dispersion, and high purity is obtained. Then, a dispersant and an initiator are added to the γ-Al2O3 / Y2O3 powder and it is subjected to ultraviolet irradiation treatment. Then, it is calcined in stages to obtain high-purity ultrafine-grained yttrium aluminum garnet ceramic powder.

[0045] The high-purity ultrafine-grained yttrium aluminum garnet ceramic powder prepared by this invention has a grain size of 20-200 nm and a uniform grain size distribution; the grain bonding of the powder is weak and it is very easy to break; the purity of the powder is higher than 99.9% and the YAG phase content is higher than 95%.

[0046] 2. This invention uses Al(OH)3, α / γ-AlOOH, metastable Al2O3 (amorphous, γ, θ, δ, etc.), Y2O3, Y(CH3COO)3, and Y(OH)3 powders as raw materials to prepare yttrium aluminum garnet ceramic powders in large quantities. The preparation process is simple, low-cost, and highly efficient. When using γ-Al2O3 and Y2O3 powders as raw materials, a preliminary low-temperature calcination process is unnecessary; only the purity needs to be improved, simplifying the preparation process and significantly reducing powder production costs. Attached Figure Description

[0047] Figure 1 Electron micrograph of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 1;

[0048] Figure 2 XRD pattern of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 1;

[0049] Figure 3 Electron micrograph of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 2;

[0050] Figure 4 XRD pattern of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 2;

[0051] Figure 5 Electron micrograph of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 3;

[0052] Figure 6 XRD pattern of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in Example 3;

[0053] Figure 7 Electron micrograph of yttrium aluminum garnet ceramic powder prepared in Comparative Example 1;

[0054] Figure 8 XRD pattern of yttrium aluminum garnet ceramic powder prepared in Comparative Example 2

[0055] Figure 9 Electron micrograph of yttrium aluminum garnet ceramic powder prepared in Comparative Example 3;

[0056] Figure 10 XRD pattern of yttrium aluminum garnet ceramic powder prepared in Comparative Example 3. Detailed Implementation

[0057] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0058] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0059] In existing technologies, solid-state synthesis is the most mature and widely used method for synthesizing yttrium aluminum garnet (YAG) ceramic powders. However, to obtain a pure YAG phase, high temperature and long calcination are required, which inevitably leads to coarse particles and severe agglomeration of the YAG ceramic powder, thus sacrificing the sintering activity of the powder. Therefore, there is an urgent need for a simple and efficient method to directly synthesize high-phase-purity, ultrafine-grained, low-agglomeration, and highly sintering-active YAG ceramic powders at relatively lower temperatures.

[0060] This invention uses aluminum / yttrium sources as raw materials. After multiple washing (acid washing, deionized water washing, etc.), pressure filtration (pore size 0.01-0.8 μm), drying (drying at 50-90 ℃ for 1-12 h), and low-temperature calcination (300-600 ℃, holding for 1-4 h), high-purity γ-Al2O3 / Y2O3 powder with good dispersibility is obtained. Then, after ultraviolet irradiation, medium-temperature calcination (900-1200 ℃, holding for 1-5 h), and high-temperature calcination (1250-1500 ℃, holding for 1-5 h), yttrium aluminum garnet ceramic powder with easy grinding, high purity, and fine grains is obtained, which can be used in semiconductor, laser and optical device fields.

[0061] The purpose of this invention's staged calcination is to control the phase transformation process in stages, ensuring both an ultrafine and uniform grain structure, preventing abnormal grain growth and agglomeration, and increasing the YAG phase content in the resulting ceramic powder. Specifically, the intermediate-temperature calcination stage forms a large number of fine YAP / YAM nuclei, which are then used as precursors to rapidly transform into the YAG phase during subsequent high-temperature calcination, while maintaining fine size characteristics. If intermediate-temperature calcination is omitted and high-temperature calcination is performed directly, it will lead to uneven and rapid reactions in the γ-Al₂O₃ / Y₂O₃ powder, resulting in unreacted intermediate phases in the product and a reduced YAG phase content. Furthermore, excessive reaction driving force can cause rapid nucleus generation and merging, easily forming coarse and uneven grains. Without high-temperature calcination, a large amount of YAP / YAM phase cannot be effectively transformed into the YAG phase, resulting in a reduced YAG phase content in the final product.

[0062] To meet the powder requirements of various fields such as lasers, lighting, and scintillators, rare earth ions are used for single or co-doping during the powder preparation stage. The main single-doped ion is Ce. 3+ 、Nd 3+ Pr 3+ Dy 3+ 、Sm 3+ The main co-dopersant is Ce. 3+ / Sm 3+ Dy 3 + / Ce 3+ In step (1), rare earth metal oxides or rare earth metal salts can be added to the system.

[0063] Furthermore, based on this invention, high-purity ultrafine-grained powders of other single-phase or multi-phase oxides can be prepared. Examples include one or more of the following: magnesium oxide, yttrium oxide, zirconium oxide, calcium oxide, strontium oxide, scandium oxide, iron oxide, molybdenum oxide, barium oxide, vanadium oxide, titanium oxide, chromium oxide, cobalt oxide, nickel oxide, niobium oxide, hafnium oxide, tantalum oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, silicon oxide, and lutetium oxide.

[0064] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0065] Example 1: Preparation of high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder.

[0066] (1) Al(OH)3 powder with a purity of 99.9%, Y2O3 powder with a purity of 99.9%, and deionized water were mixed in a mass ratio of 1.15:1:3 to obtain a uniform Al(OH)3 / Y2O3 slurry; the uniform Al(OH)3 / Y2O3 slurry was washed twice with hydrochloric acid and deionized water, then washed once with ion exchange resin, and then placed under 0.3 MPa for pressure filtration with a pore size of 0.05 μm. Finally, it was dried at 80 ℃ for 5 h to obtain dried Al(OH)3 / Y2O3 powder; the dried Al(OH)3 / Y2O3 powder was heated to 500 ℃ at a heating rate of 50 ℃ / min, held for 2 h for low-temperature calcination, then cooled to 150 ℃ at a cooling rate of 20 ℃ / min, and then furnace cooled to room temperature to obtain γ-Al2O3 / Y2O3 powder;

[0067] (2) After mixing polyacrylamide and polyethylene glycol at a mass ratio of 1:0.8, a dispersant is obtained; after mixing YAG (seed crystal) and AlF3 (mineralizer) at a mass ratio of 1:0.5, an initiator is obtained; after mixing γ-Al2O3 / Y2O3 powder, dispersant, initiator and deionized water at a mass ratio of 1:0.005:0.02:4, a composite homogeneous slurry is obtained;

[0068] After drying and pulverizing the composite homogeneous slurry, it was irradiated with ultraviolet light for 4 hours, then heated to 1000℃ at a heating rate of 50℃ / min and held for 3 hours for medium-temperature calcination. Then, it was heated to 1400℃ at a heating rate of 20℃ / min and held for 2 hours for high-temperature calcination. Finally, it was cooled to 800℃ at a cooling rate of 25℃ / min and then furnace cooled to room temperature to obtain high-purity ultrafine-grained yttrium aluminum garnet ceramic powder.

[0069] In this embodiment, the high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder has a spherical structure, such as...Figure 1 As shown, the grain size is between 50-200 nm, with a uniform grain size distribution, mostly concentrated between 80-120 nm; however, there are numerous pores between the grains, making them easily pulverized. Testing revealed that the purity of the YAG powder prepared in this example is higher than 99.9%, and the YAG phase content is higher than 97.5%. Figure 2 As shown.

[0070] Example 2: Preparation of high-purity ultrafine grain yttrium aluminum garnet ceramic powder.

[0071] (1) A homogeneous slurry of γ-AlOOH / γ-Al2O3 / Y2O3 was prepared by mixing γ-AlOOH powder with a purity of 99.9%, γ-Al2O3 powder with a purity of 99.8%, Y2O3 powder with a purity of 99.9%, and deionized water in a mass ratio of 1.18:1:1.41:4.77. The homogeneous slurry of γ-AlOOH / γ-Al2O3 / Y2O3 was washed twice with hydrochloric acid and deionized water, and then washed once with ion exchange resin. It was then subjected to pressure filtration at 0.8 MPa with a pore size of 0.2 μm. Finally, it was dried at 50℃ for 10 h to obtain dried γ-AlOOH / γ-Al2O3 / Y2O3 powder. The dried γ-AlOOH / γ-Al2O3 / Y2O3 powder was heated to 550℃ at a heating rate of 5℃ / min. The temperature was set at ℃ and kept at that temperature for 2 hours for low-temperature calcination. Then, the temperature was lowered to 100℃ at a rate of 5℃ / min and then furnace cooled to room temperature to obtain γ-Al2O3 / Y2O3 powder.

[0072] (2) After mixing polyacrylamide and polyethylene glycol at a mass ratio of 1:0.1, a dispersant is obtained; after mixing YAG (seed crystal) and AlF3 (mineralizing agent) at a mass ratio of 1:0.3, an initiator is obtained;

[0073] A composite homogeneous slurry was prepared by mixing γ-Al2O3 / Y2O3 powder, dispersant, initiator, and deionized water at a mass ratio of 1:0.05:0.05:5. After drying, the composite homogeneous slurry was pulverized and irradiated with ultraviolet light for 8 h. Then, it was heated to 900 ℃ at a heating rate of 100 ℃ / min and held at that temperature for 5 h for medium-temperature calcination. Next, it was heated to 1300 ℃ at a heating rate of 20 ℃ / min and held at that temperature for 2.5 h for high-temperature calcination. Finally, it was cooled to 700 ℃ at a cooling rate of 10 ℃ / min and then furnace cooled to room temperature to obtain high-purity ultrafine-grained yttrium aluminum garnet ceramic powder.

[0074] In this embodiment, the high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder has two types of spherical structures, such as... Figure 3As shown, the obtained grain size is 20-200 nm, with small particle size concentrated in 40-80 nm and large particle size concentrated in 150-200 nm. This dual-size structure is very beneficial for the densification of ceramics; at the same time, there are a large number of pores between the grains, making them easy to crush. Testing showed that the purity of the YAG powder prepared in this example is higher than 99.99%, and the YAG phase content is higher than 97.2%. Figure 4 As shown.

[0075] Example 3: Preparation of high-purity ultrafine grain yttrium aluminum garnet ceramic powder.

[0076] (1) γ-Al2O3 powder with a purity of 99.9%, Y2O3 powder with a purity of 99.9%, and deionized water were mixed in a mass ratio of 0.75:1:5.25 to obtain a uniform γ-Al2O3 / Y2O3 slurry; the uniform γ-Al2O3 / Y2O3 slurry was washed twice with hydrochloric acid and deionized water, then washed once with ion exchange resin, and then placed under 4.0 MPa for pressure filtration with a pore size of 0.8 μm. Finally, it was dried at 90 ℃ for 1 h to obtain dried γ-Al2O3 / Y2O3 powder;

[0077] (2) After mixing polyacrylamide and polyethylene glycol at a mass ratio of 1:1.4, a dispersant is obtained; after mixing YAG (seed crystal) and AlF3 (mineralizing agent) at a mass ratio of 1:0.6, an initiator is obtained;

[0078] A composite homogeneous slurry was prepared by mixing γ-Al2O3 / Y2O3 powder, dispersant, initiator, and deionized water at a mass ratio of 1:0.02:0.05:4. After drying, the composite homogeneous slurry was pulverized and irradiated with ultraviolet light for 6 h. Then, it was heated to 1000 ℃ at a heating rate of 20 ℃ / min and held at that temperature for 3 h for medium-temperature calcination. Next, it was heated to 1500 ℃ at a heating rate of 20 ℃ / min and held at that temperature for 0.5 h for high-temperature calcination. Finally, it was cooled to 900 ℃ at a cooling rate of 15 ℃ / min and then furnace cooled to room temperature to obtain high-purity ultrafine-grained yttrium aluminum garnet ceramic powder.

[0079] like Figure 5 As shown, the high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared in this embodiment has a near-spherical structure, with a grain size of 30-200 nm. The grain size distribution is uniform, and there are numerous pores between the grains, making it easy to pulverize. Testing revealed that the purity of the YAG powder prepared in this example is higher than 99.99%, and the YAG phase content is higher than 98.8%. Figure 6 As shown.

[0080] Comparative Example 1:

[0081] The difference between this comparative example and Example 1 is that no ultraviolet irradiation treatment was performed in step (2). Specifically,

[0082] γ-Al2O3 / Y2O3 powder, dispersant, and initiator were prepared using the method described in Example 1. The γ-Al2O3 / Y2O3 powder, dispersant, initiator, and deionized water were mixed at a mass ratio of 1:0.005:0.02:4 to obtain a composite homogeneous slurry. After drying and pulverizing the composite homogeneous slurry, it was heated to 1000 ℃ at a heating rate of 50 ℃ / min and held at that temperature for 3 h for medium-temperature calcination. Then, it was heated to 1400 ℃ at a heating rate of 20 ℃ / min and held at that temperature for 2 h for high-temperature calcination. Finally, it was cooled to 800 ℃ at a cooling rate of 25 ℃ / min and then furnace cooled to room temperature to obtain yttrium aluminum garnet ceramic powder.

[0083] Depend on Figure 7 It can be seen that, due to the lack of ultraviolet irradiation, the YAG grains exhibited abnormal growth, resulting in an extremely uneven grain size distribution.

[0084] Comparative Example 2:

[0085] The difference between this comparative example and Example 1 is that in step (2), high-temperature calcination was not performed; only medium-temperature calcination was performed. Specifically,

[0086] γ-Al2O3 / Y2O3 powder, dispersant, and initiator were prepared using the method in Example 1. The γ-Al2O3 / Y2O3 powder, dispersant, initiator, and deionized water were mixed at a mass ratio of 1:0.005:0.02:4 to obtain a composite homogeneous slurry. The composite homogeneous slurry was dried and pulverized. After being irradiated with ultraviolet light for 4 h, it was heated to 1000 °C at a heating rate of 50 °C / min and held at that temperature for 3 h for medium-temperature calcination. Then, it was cooled to 800 °C at a cooling rate of 25 °C / min and then furnace cooled to room temperature to obtain yttrium aluminum garnet ceramic powder.

[0087] Depend on Figure 8 It can be seen that, due to the lack of high-temperature calcination, the final yttrium aluminum garnet ceramic powder contains a large amount of YAM / YAP phase, while the YAG phase is significantly reduced to 45.5%.

[0088] Comparative Example 3:

[0089] The difference between this comparative example and Example 1 is that in step (2), only high-temperature calcination was performed, without medium-temperature calcination. Specifically,

[0090] γ-Al2O3 / Y2O3 powder, dispersant, and initiator were prepared using the method in Example 1. The γ-Al2O3 / Y2O3 powder, dispersant, initiator, and deionized water were mixed at a mass ratio of 1:0.005:0.02:4 to obtain a composite homogeneous slurry. The composite homogeneous slurry was dried and pulverized. After being irradiated with ultraviolet light for 4 h, it was heated to 1400 ℃ at a heating rate of 50 ℃ / min and held at that temperature for 2 h for high-temperature calcination. Finally, it was cooled to 800 ℃ at a cooling rate of 25 ℃ / min and then furnace cooled to room temperature to obtain high-purity ultrafine-grained yttrium aluminum garnet ceramic powder.

[0091] Depend on Figure 9 It can be seen that, due to the lack of a medium-temperature calcination process, the resulting ceramic powder contains coarse and uneven grains; and, due to... Figure 10 It can be seen that the prepared ceramic powder contains a small amount of unconverted YAP phase, resulting in a YAG phase content of only 94.5%, which is lower than the YAG phase content of the powder prepared in Example 1.

[0092] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder, characterized in that, Includes the following steps: (1) Aluminum source powder, yttrium source powder and deionized water are mixed in proportion to obtain a uniform slurry; the uniform slurry is washed, filtered and dried, and then calcined at low temperature to obtain γ-Al2O3 / Y2O3 powder; (2) Mix γ-Al2O3 / Y2O3 powder, dispersant, initiator and water in proportion to obtain composite homogeneous slurry; dry and pulverize the composite homogeneous slurry and then irradiate it with ultraviolet light for 0.5-10 h, and then calcine it at medium temperature and high temperature in sequence to obtain high-purity ultrafine grain yttrium aluminum garnet ceramic powder. The dispersant is composed of polyacrylamide and polyethylene glycol in a mass ratio of 1:(0.1-1.4); the initiator is composed of seed crystals and mineralizer in a mass ratio of 1:(0.1-1); the seed crystal is YAG; the mineralizer is AlF3; the mass ratio of γ-Al2O3 / Y2O3 powder, dispersant, initiator and water is 1:(0.005-0.05):(0.02-0.05):(4-5); The specific operation for medium-temperature calcination is as follows: heat up to 900-1000 ℃ at a heating rate of 20-100 ℃ / min and hold for 1-5 hours; the specific operation for high-temperature calcination is as follows: heat up to 1300-1500 ℃ at a heating rate of 20 ℃ / min and hold for 1-5 hours, then cool down to 700-900 ℃ at a cooling rate of 10-25 ℃ / min, and then furnace cool to room temperature.

2. The method for preparing high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder as described in claim 1, characterized in that, In step (1), the aluminum source powder is one or more of Al(OH)3, α / γ-AlOOH, and metastable phase Al2O3; the yttrium source powder is one or more of Y2O3, Y(CH3COO)3, and Y(OH)3; the total mass ratio of the aluminum source powder and the yttrium source powder to the deionized water is 1:(0.5-8).

3. The method for preparing high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder as described in claim 1, characterized in that, In step (1), the pressure for filtration is 0.1-4.5 MPa, the pore size for filtration is 0.01-0.8 μm, the drying temperature is 50-90 ℃, and the drying time is 1-12 h.

4. The method for preparing high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder as described in claim 1, characterized in that, In step (1), the specific steps of low-temperature calcination are as follows: heat up to 300-600 ℃ at a heating rate of 1-200 ℃ / min, hold for 1-4 h, then cool down to 100-200 ℃ at a cooling rate of 5-100 ℃ / min, and then furnace cool to room temperature.

5. The high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder prepared by the preparation method according to any one of claims 1-4, characterized in that, The high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder has a grain size of 20-200 nm, a purity of >99.9%, and a YAG phase content of >95%.

6. The application of the high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder according to claim 5 in the preparation of transparent laser ceramics, scintillator ceramics, and fluorescence conversion materials.

7. The application as described in claim 6, characterized in that, When using the high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder described in claim 5 to prepare transparent laser ceramics and scintillator ceramics, granulation treatment is required. The specific operation of the granulation treatment is as follows: The high-purity, ultrafine-grained yttrium aluminum garnet ceramic powder described in claim 5 is pulverized and mixed with a dispersant and ultrapure water to obtain a uniform YAG slurry; the uniform YAG slurry is then spray-dried to obtain granulated YAG powder. The dispersant is composed of polyacrylamide and polyethylene glycol in a mass ratio of 1:(0.1-1.4); the mass ratio of the high-purity ultrafine grain yttrium aluminum garnet ceramic powder, the dispersant, and water described in claim 5 is 1:(0-0.01):(0.5-8).

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