Preparation method of yttrium oxide powder

Abstract

This invention discloses a method for preparing yttrium oxide powder, belonging to the field of inorganic non-metallic material preparation technology. The method uses a yttrium source as raw material, prepares a yttrium solution by dissolving it in a strong acid, controls the co-precipitation reaction through a constant-temperature water bath, precisely regulates the temperature, precipitant ratio, and pH, and combines washing with a mixed detergent and slurry preparation with dispersant control. The resulting yttrium oxide powder is obtained through spray / constant-temperature drying and calcination. The powder prepared by this invention has uniform particle size, high purity, no impurity phases, and uniform agglomerate dispersion. Compared with the traditional ball milling method, energy consumption is reduced by more than 67%, the production cycle is shortened by more than 47%, and the process repeatability is excellent. This powder can be widely used in high-end fields such as aerospace thermal barrier coatings, electronic devices, and fluorescent materials.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic material preparation technology, and more specifically, to a method for preparing yttrium oxide powder. Background Technology

[0002] Yttrium oxide, as a key rare earth oxide, occupies an irreplaceable position in high-end fields such as aerospace, fluorescent materials, electronic devices, and high-tech ceramics due to its outstanding properties, including high dielectric constant, excellent heat resistance, and strong corrosion resistance. For example, in the aerospace field, gas turbines need to operate for extended periods in high-temperature environments, and high-performance thermal barrier coatings rely on high-purity, highly dispersed yttrium oxide to achieve efficient thermal insulation between the working substrate and the working end, ensuring stable operation of the substrate at suitable temperatures. In the electronics and fluorescence fields, the purity and phase stability of yttrium oxide directly determine the performance and lifespan of devices.

[0003] Currently, methods for preparing yttrium oxide include ball milling, solvent extraction, precipitation, sol-gel, hydrothermal, and combustion methods. Among these, ball milling has become a commonly used technique for preparing high-performance yttrium oxide due to its ability to enhance sintering activity, control crystal defects, improve phase transformation, optimize dispersibility, and regulate particle size at room temperature. This method uses milling balls as a medium, achieving material pulverization through impact, compression, and friction. Mechanical force induces physical and chemical changes in the material, thereby refining grains and improving material properties.

[0004] However, the traditional method of synthesizing yttrium oxide by ball mill spray granulation has many insurmountable technical drawbacks: First, it has extremely low energy efficiency. During ball mill operation, most of the energy is used to lift the grinding balls, overcome mechanical friction, and generate heat. The effective energy that actually acts on particle crushing and dispersion is usually less than 1%. Furthermore, the equipment structure is complex, the cleaning of the grinding jar and sealing system is cumbersome, cross-contamination is prone to occur during material changes, and the grinding balls experience natural wear and tear, requiring regular inspection, screening, and replenishment, significantly increasing maintenance costs and workload. Second, the production cycle is lengthy. To achieve the target particle size and dispersion effect, grinding time often requires several hours or even tens of hours, resulting in high energy consumption per unit output. Third... Purity control is difficult. During ball milling, the intense impact and friction between the grinding balls and the material, between the balls themselves, and between the balls and the inner wall of the jar can cause wear on the grinding balls and the lining material of the jar. Wear debris is directly mixed into the slurry, forming impurities and contaminating the product, which seriously affects the purity of the product. Fourth, the process repeatability is poor. Multiple parameters such as grinding time, ball-to-material ratio, ball diameter ratio, rotation speed, and slurry solid content can all affect the purity, particle size, and phase composition of the powder. Even small fluctuations in these parameters can lead to performance differences between batches. Fifth, the process compatibility is insufficient. Air entrained during ball milling can form microbubbles, causing the slurry to exhibit pseudo-plasticity, which affects the quality of subsequent processes such as spraying and casting. In addition, the large amount of heat generated by mechanical friction can easily cause heat-sensitive additives to decompose and become ineffective.

[0005] While there are existing reports on the preparation of ceramic materials using co-precipitation methods, such as the method for preparing metal oxide-doped YSZ electrolyte ceramics based on co-precipitation disclosed in CN108409337A, the core purpose of this method is to prepare metal oxide-doped YSZ composite electrolyte ceramics. This requires the introduction of zirconium oxychloride and metal dopant salts into the system, and the process design revolves around the component control and sintering performance optimization of the composite ceramic. This technology cannot be directly applied to the preparation of high-purity yttrium oxide powder, and it does not address the core requirements of energy consumption optimization, precise phase control, and particle size uniformity regulation during the yttrium oxide powder preparation process. Therefore, it cannot solve the technical problems of high energy consumption, low purity, and poor repeatability inherent in the traditional ball milling method for preparing pure yttrium oxide. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing yttrium oxide powder, so as to solve the technical problems existing in the background art.

[0007] The present invention provides a method for preparing yttrium oxide powder, comprising the following preparation steps:

[0008] (1) Preparation of yttrium solution: Weigh the yttrium source powder and dissolve it in a strong acid to prepare a yttrium solution with a concentration of 1-2 mol / L. Determine the concentration of the yttrium source through acid-base titration experiment and calculate the amount of oxalate ions, carbonate ions or bicarbonate ions required.

[0009] (2) Coprecipitation reaction: The yttrium source solution from step (1) is transferred to a constant temperature water bath reaction vessel. The reaction temperature is controlled at 25-45℃. 30wt% mixed precipitant is added dropwise at a rate of 0.6-1.4mL / min using a precision peristaltic pump. The mass ratio of HCO3²⁻ to CO3²⁻ in the mixed precipitant is 95:5. The pH of the system is monitored in real time during the dropwise addition. When the pH reaches 8.5-9.5, the dropwise addition is stopped. Stirring is continued for 30-40min to generate a white mixture. The pH of the solution is adjusted with ammonia water before precipitation aging.

[0010] (3) Washing treatment: The aged precursor solution was transferred to an electric mixer and stirred evenly at a speed of 200 rpm / min. It was then washed with a mixed detergent in which the volume ratio of deionized water to ethanol was 60:40, and the precipitate was separated.

[0011] (4) Slurry preparation: Prepare the precipitate from step (3) into a slurry with a solid content of 40%-60%, and slowly add the dispersant to the slurry at a molar ratio of Y³⁺ to dispersant of 1:0.5-1.6;

[0012] (5) Spray granulation: Transfer the above precursor slurry to the granulation tower, adjust the inlet and outlet temperatures and the pressure difference inside the tower, and spray granulation at a feeding rate of 20 mL / min and an atomizing disc frequency of 35-55 Hz. After spraying, allow it to cool naturally to room temperature.

[0013] (6) Drying and calcination: The granulated yttrium hydroxide precursor is placed in a vacuum drying oven and dried at 60-80℃ for 5-8h to obtain a white powder. The white powder is then calcined at 600-1000℃ for 2.5-4.5h to obtain highly dispersible yttrium oxide powder.

[0014] In a preferred embodiment, the strong acid in step (1) is selected from nitric acid, hydrochloric acid, sulfuric acid or perchloric acid.

[0015] In a preferred embodiment, the yttrium source in step (1) is selected from one of yttrium oxide, yttrium chloride, yttrium acetate, yttrium sulfate, and yttrium perchlorate.

[0016] In a preferred embodiment, the mixed precipitant in step (2) can be replaced with ammonia, ammonium carbonate, ammonium bicarbonate or their complex, and the molar ratio of the precipitant to Y³⁺ is 1:6-13; during the coprecipitation reaction in step (2), an easily decomposable mineralizing agent is added at a molar ratio of mineralizing agent to Y³⁺ of 1:7, and the easily decomposable mineralizing agent is selected from ammonium chloride or ammonium nitrate.

[0017] In a preferred embodiment, the washing process in step (3) is assisted by centrifugal separation, with a centrifugal speed of 2800 rpm / min and a centrifugal time of 5 min.

[0018] In a preferred embodiment, after adding the dispersant in step (4), the mixture is magnetically stirred for 10 minutes to ensure that the dispersant is evenly dispersed in the slurry.

[0019] In a preferred embodiment, the dispersant in step (4) is selected from one or more combinations of polyethylene glycol (PEG-6000), hexadecyltrimethylammonium bromide (CTAB), or CE-64.

[0020] In a preferred embodiment, spray granulation in step (5) can be replaced by constant temperature heating and drying, where the slurry is dried at 120°C and then directly calcined.

[0021] In a preferred embodiment, the calcination temperature in step (6) is 800°C and the calcination time is 2.5 h.

[0022] The beneficial effects of the technical solution of this invention are:

[0023] This invention prepares yttrium oxide precursor slurry via co-precipitation. With controlled process parameters, the resulting yttrium oxide powder exhibits uniform particle size, high purity, good dispersibility, and high sintering activity. Low- and high-magnification SEM images visually verify the powder's microstructure, revealing uniform overall dispersion and porous, spherical particles—the primary reason for its superior performance compared to traditional ball milling methods. Compared to existing solutions, this invention significantly improves key indicators such as particle size uniformity, purity, and specific surface area, while reducing energy consumption and production cycle time. It also offers better process repeatability and can be widely applied in high-end fields such as aerospace, fluorescent materials, and electronic devices, demonstrating significant industrial application value. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the preparation process of yttrium oxide powder according to the present invention.

[0025] Figure 2 This is a scanning electron microscope image of Embodiment 1 of the present invention.

[0026] Figure 3 This is a scanning electron microscope image at another magnification of Embodiment 1 of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail. The embodiments of the invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0028] like Figure 1 The diagram shown is a flowchart of the preparation process for this method.

[0029] Example 1

[0030] In this embodiment, yttrium oxide is used as the yttrium source, nitric acid as the strong acid, and ammonia as the precipitant. Yttrium oxide powder is prepared by spray granulation-calcination process. The specific steps are as follows:

[0031] (1) Preparation of yttrium solution: Weigh 5.0g of yttrium oxide powder (purity ≥99.9%), slowly add 20mL of concentrated nitric acid (mass fraction 68%), stir at room temperature until completely dissolved to obtain a yttrium nitrate solution with a concentration of about 2mol / L; take 10mL of the yttrium nitrate solution, dilute with deionized water to 50mL, and prepare a yttrium salt solution with a concentration of 0.4mol / L; determine the concentration of the yttrium source by acid-base titration experiment (using 0.1mol / L sodium hydroxide standard solution as titrant and phenolphthalein as indicator), and calculate the theoretical amount of carbonate ions required.

[0032] (2) Coprecipitation reaction: The above 0.4 mol / L yttrium salt solution was transferred to a 500 mL constant temperature water bath reaction vessel, and the water bath temperature was set to 35℃ (temperature control accuracy ±1℃). Using a precision peristaltic pump, 35% ammonia water (analytical grade, concentration about 16 mol / L) was added dropwise to the solution at a rate of 1.4 mL / min. The molar ratio of precipitant to Y³⁺ was 1:8. During the dropwise addition, the pH of the system was monitored in real time using a pH meter. When the pH reached 9.0, the dropwise addition was stopped. The mixture was stirred at 200 rpm / min for 30 min to generate a milky white yttrium hydroxide colloid. Ammonium chloride, a mineralizing agent, was added to the colloid. The molar ratio of mineralizing agent to Y³⁺ was 1:7. The mixture was magnetically stirred for 10 min to form a "yttrium hydroxide-mineralizing agent" composite dispersion system. The mixture was allowed to stand and age at room temperature for 2 h.

[0033] (3) Washing treatment: Transfer the aged composite dispersion system to a centrifuge and centrifuge at 2800 rpm / min for 5 min, discard the supernatant; add 50 mL of mixed detergent (deionized water: ethanol = 60:40, volume ratio) to the precipitate, stir at 200 rpm / min for 10 min in an electric stirrer, and centrifuge again; repeat washing 3 times until there is no Cl⁻ in the supernatant (titration with 0.1 mol / L silver nitrate solution showed no white precipitate), and obtain pure precipitate.

[0034] (4) Slurry preparation: Mix the washed precipitate with deionized water to prepare a slurry with a solid content of 40%; add polyethylene glycol (PEG-6000) slowly to the slurry at a molar ratio of Y³⁺ to dispersant of 1:0.5, and stir magnetically for 10 minutes to ensure that the dispersant is evenly dispersed in the slurry and to avoid particle agglomeration.

[0035] (5) Spray granulation: Transfer the prepared precursor slurry to a centrifugal spray granulation tower, set the inlet temperature of the granulation tower to 180℃ and the outlet temperature to 80℃, and control the pressure difference in the tower to -5kPa; adjust the peristaltic pump feeding rate to 20mL / min and the atomizing plate frequency to 40Hz, and carry out spray granulation; after the spraying is completed, turn off the equipment, wait for the tower to cool naturally to room temperature, and collect the granulated yttrium hydroxide precursor particles.

[0036] (6) Drying and calcination: The granulated yttrium hydroxide precursor was placed in a vacuum drying oven, and the temperature was set to 70℃ and the vacuum degree to -0.09MPa. It was dried for 5h to obtain a white powder. The white powder was placed in a muffle furnace and heated to 800℃ at a heating rate of 5℃ / min. It was kept at the temperature for 2.5h for calcination. After naturally cooling to room temperature, it was taken out to obtain yttrium oxide powder.

[0037] Example 2

[0038] In this embodiment, yttrium chloride is used as the yttrium source, hydrochloric acid as the strong acid, and ammonium bicarbonate as the precipitant. Other process parameters are adapted to those in Example 1. The specific steps are as follows:

[0039] (1) Preparation of yttrium solution: Weigh 7.3g of yttrium chloride powder (YCl3・6H2O, purity ≥99.9%), add 30mL of concentrated hydrochloric acid (mass fraction 37%), stir and dissolve in a 40℃ water bath to obtain a yttrium chloride solution with a concentration of about 2mol / L; take 10mL of this solution, dilute it with deionized water to 50mL, and prepare a yttrium salt solution with a concentration of 0.4mol / L; determine the concentration of the yttrium source by acid-base titration, and calculate the theoretical amount of bicarbonate ions.

[0040] (2) Coprecipitation reaction: The yttrium salt solution was transferred to a constant temperature water bath reaction vessel and the temperature was set to 30℃. A 35% ammonium bicarbonate solution (analytical grade) was added dropwise at a rate of 1.4 mL / min using a precision peristaltic pump. The molar ratio of the precipitant to Y³⁺ was 1:10. The pH was monitored in real time. When the pH reached 8.8, the dropwise addition was stopped and the mixture was stirred for 30 min to generate yttrium hydroxide colloid. Ammonium nitrate was added as a mineralizing agent (the molar ratio of the mineralizing agent to Y³⁺ was 1:7). The mixture was magnetically stirred for 10 min and allowed to stand for 2 h for aging.

[0041] (3) Washing treatment: Using the same centrifugation parameters as in Example 1 (2800 rpm / min, 5 min) and mixed detergent, the washing was repeated 3 times (3 water washes + 3 ethanol washes) to ensure the removal of impurity ions and obtain pure precipitate.

[0042] (4) Slurry preparation: Prepare the precipitate into a slurry with a solid content of 40%, add polyethylene glycol (PEG-6000) at a molar ratio of Y³⁺ to dispersant of 1:0.5, and stir magnetically for 10 minutes until it is evenly dispersed.

[0043] (5) Spray granulation: The parameters of the granulation tower are the same as those in Example 1 (inlet temperature 180℃, outlet temperature 80℃, pressure difference in the tower -5kPa, feeding rate 20mL / min, atomizing plate frequency 40Hz). After spraying, the tower is naturally cooled and the precursor particles are collected.

[0044] (6) Drying and calcination: The vacuum drying conditions (70℃, 5h) and calcination conditions (800℃, 2.5h) are the same as in Example 1, and highly dispersed yttrium oxide powder is finally obtained.

[0045] Example 3

[0046] This embodiment uses constant temperature heating and drying instead of spray granulation. Other process parameters are the same as in Example 1. The specific steps are as follows:

[0047] (1) Preparation of yttrium solution: The same as step 1 in Example 1, to obtain a 0.4 mol / L yttrium nitrate solution.

[0048] (2) Coprecipitation reaction: exactly the same as step 2 in Example 1, to obtain the "yttrium hydroxide-ammonium chloride" composite dispersion system, and age for 2 hours.

[0049] (3) Washing treatment: exactly the same as step 3 in Example 1, to obtain pure precipitate.

[0050] (4) Slurry preparation and constant temperature drying: The precipitate was prepared into a slurry with a solid content of 40%. After adding polyethylene glycol (PEG-6000) and dispersing it evenly, it was transferred to a stainless steel tray and placed in a constant temperature drying oven at 120℃. It was slowly dried for 12 hours. After taking it out, it was ground with an agate mortar and passed through a 200-mesh sieve to obtain a white powder precursor.

[0051] (5) Calcination: The sieved precursor powder is placed in a muffle furnace and calcined at 800℃ for 2.5h. After natural cooling, yttrium oxide powder is obtained.

[0052] Comparative Example

[0053] This comparative example uses the traditional ball milling method to prepare yttrium oxide powder. The specific steps are as follows:

[0054] (1) Slurry preparation: Weigh 5.0g of yttrium oxide powder (purity ≥99.9%), 0.25g of dispersant polyethylene glycol (PEG-6000), and 0.5g of mineralizer sodium chloride, add them to 50mL of deionized water, and stir in an electric mixer at 200rpm / min for 30min to form a uniform slurry mixture.

[0055] (2) Slurry ball milling: Transfer the above slurry mixture to a stainless steel ball mill jar lined with polytetrafluoroethylene, add zirconia grinding balls with a diameter of 5 mm, and the ball-to-material ratio is 10:1; set the ball mill speed to 250 rpm and the ball milling time to 3 h; take a sample every 30 min during the ball milling process and test the particle size with a Malvern laser particle size analyzer until the average particle size of the slurry stabilizes at 2.0-3.0 μm, thus completing the slurry refinement.

[0056] (3) Spray granulation: Transfer the ball-milled slurry to the granulation tower, set the inlet temperature to 180℃, the outlet temperature to 80℃, the peristaltic pump feeding rate to 20mL / min, and the atomizing disc frequency to 40Hz, and carry out spray granulation; after spraying, allow it to cool naturally and collect the granulated powder.

[0057] (4) Post-sintering treatment: The granulated powder is placed in a muffle furnace and heated to 1400℃ at a heating rate of 5℃ / min. It is then held at the temperature for 3 hours for sintering. After naturally cooling to room temperature, the yttrium oxide powder is obtained.

[0058] Performance Testing and Result Analysis

[0059] The performance of the yttrium oxide powders prepared in the above three examples and comparative examples was tested. The test items included particle size distribution, purity, specific surface area, phase composition, and dispersibility. The test methods are as follows:

[0060] Particle size distribution: The particle size distribution of the powder was tested using a Malvern laser particle size analyzer (model: Mastersizer3000) with deionized water as the test medium and ultrasonic dispersion for 5 min.

[0061] Purity testing: The content of impurity elements (Fe, Ca, Si, Zr, etc.) in the powder was detected by inductively coupled plasma mass spectrometry (ICP-MS, model: Agilent 7900), and the purity was calculated.

[0062] Specific surface area: The specific surface area of ​​the powder was tested using the liquid nitrogen adsorption method (BET, model: TriStarII3020) under degassing conditions of 105℃ for 2h.

[0063] Phase composition: The phase composition of the powder was analyzed using an X-ray diffractometer (XRD, model: Bruker D8 Advance), with a scanning range of 2θ = 20°-80° and a scanning rate of 5° / min.

[0064] Dispersion: The proportion of aggregates was quantified by combining SEM images and using image analysis.

[0065] Energy consumption during preparation: The energy consumption throughout the process is recorded by the equipment energy consumption monitoring instrument, and the energy consumption per unit mass of powder is calculated.

[0066] Production cycle: The total time from raw material preparation to finished product output (excluding equipment preheating time). Test results:

[0067] Test Project Example 1 Example 2 Example 3 Comparative Example Average particle size (μm) 0.8-1.2 0.9-1.3 1.0-1.4 2.0-3.5 purity(%) ≥99.95 ≥99.94 ≥99.93 99.75 Specific surface area (m² / g) 15-18 14-17 13-16 8-10 Phase composition <![CDATA[Pure Y2O3]]> <![CDATA[Pure Y2O3]]> <![CDATA[Pure Y2O3]]> <![CDATA[Y2O3 + trace ZrO2 impurity phase]]> Dispersion (proportion of aggregates) ≤5% ≤7% ≤10% ≥35% Energy consumption for preparation (kWh / kg) ≤8.5 ≤9.0 ≤7.8 28.6 Production cycle (h) 12-14 12-14 15-16 30-32

[0068] Results analysis:

[0069] 1. Particle size and dispersibility: Figure 2 and Figure 3 The images shown are SEM images of Example 1 under different magnifications. Figure 2 The powder showed no obvious agglomeration. Figure 3 This shows that the individual particles have a porous spherical structure, which results in the agglomerate content of Example 1 being ≤5%, far lower than the ≥35% of the comparative example. In contrast, the powder in the comparative example has irregular particle morphology and large size differences due to the "mechanical impact friction" during ball milling, and the debris generated by the wear of the grinding balls easily adheres to the particle surface, further aggravating agglomeration.

[0070] 2. Purity and Phase: The powders from Examples 1-3 all had a purity ≥99.93%, and the single phase was pure Y₂O₃; while the comparative example had a purity of only 99.75%, and a trace amount of ZrO₂ impurity phase was introduced due to the wear of the grinding balls. This verifies that the present invention avoids impurity contamination at the source by replacing mechanical grinding with chemical synthesis.

[0071] 3. Specific surface area and sintering activity: The specific surface area of ​​Example 1 (15-18 m² / g) was significantly higher than that of the comparative example (8-10 m² / g). This difference is related to... Figure 2 and Figure 3 The porous single-particle structure shown is directly related to the fact that the porous structure increases the surface active sites of the powder, which enables the powder of Example 1 to be densified at 800°C; while the powder of the comparative example, due to its smooth particle surface and severe agglomeration, needs to be sintered at a high temperature of 1400°C, which significantly increases energy consumption.

[0072] 4. Energy Consumption and Production Cycle: The energy consumption for preparation in this example is ≤9.0 kWh / kg, and the production cycle is ≤16 hours, representing reductions of over 67% and 47% respectively compared to the comparative example. This significant advantage stems from... Figure 1 The process route replaces the energy-intensive ball milling step, and the coprecipitation chemical synthesis does not require high-speed mechanical operation, which greatly reduces energy consumption, simplifies the process flow, and shortens the production cycle.

[0073] 5. Repeatability: Three parallel experiments were conducted on Examples 1-3 and the comparative example respectively. The results showed that the relative standard deviation (RSD) of the average particle size, purity, and specific surface area of ​​the examples were all ≤3%, while the RSD of the comparative example was ≥8%. This indicates that the process parameters of the present invention are easy to control and have good repeatability, solving the batch difference problem caused by the sensitivity of multiple parameters in the traditional ball milling method, and is more suitable for industrial mass production.

[0074] This invention prepares yttrium oxide precursor slurry via co-precipitation. With controlled process parameters, the resulting yttrium oxide powder exhibits uniform particle size, high purity, good dispersibility, and high sintering activity. Low- and high-magnification SEM images visually verified the powder's microstructure, revealing uniform overall dispersion and porous, spherical particles—the primary reason for its superior performance compared to traditional ball milling methods. Compared to existing solutions, this invention significantly improves key indicators such as particle size uniformity, purity, and specific surface area, while reducing energy consumption and production cycle time. It also offers better process repeatability and can be widely applied in high-end fields such as aerospace, fluorescent materials, and electronic devices, demonstrating significant industrial application value.

[0075] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art or related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A method for preparing yttrium oxide powder, characterized in that, The preparation steps include the following: (1) Preparation of yttrium solution: Weigh the yttrium source powder and dissolve it in a strong acid to prepare a yttrium solution with a concentration of 1-2 mol / L. Determine the concentration of the yttrium source through acid-base titration experiment and calculate the amount of oxalate ions, carbonate ions or bicarbonate ions required. (2) Coprecipitation reaction: The yttrium source solution from step (1) is transferred to a constant temperature water bath reaction vessel. The reaction temperature is controlled at 25-45℃. 30wt% mixed precipitant is added dropwise at a rate of 0.6-1.4mL / min using a precision peristaltic pump. The mass ratio of HCO3²⁻ to CO3²⁻ in the mixed precipitant is 95:

5. The pH of the system is monitored in real time during the dropwise addition. When the pH reaches 8.5-9.5, the dropwise addition is stopped. Stirring is continued for 30-40min to generate a white mixture. The pH of the solution is adjusted with ammonia water before precipitation aging. (3) Washing treatment: The aged precursor solution was transferred to an electric mixer and stirred evenly at a speed of 200 rpm / min. It was then washed with a mixed detergent in which the volume ratio of deionized water to ethanol was 60:40, and the precipitate was separated. (4) Slurry preparation: Prepare the precipitate from step (3) into a slurry with a solid content of 40%-60%, and slowly add the dispersant to the slurry at a molar ratio of Y³⁺ to dispersant of 1:0.5-1.6; (5) Spray granulation: Transfer the above precursor slurry to the granulation tower, adjust the inlet and outlet temperatures and the pressure difference inside the tower, and spray granulation at a feeding rate of 20 mL / min and an atomizing disc frequency of 35-55 Hz. After spraying, allow it to cool naturally to room temperature. (6) Drying and calcination: The granulated yttrium hydroxide precursor is placed in a vacuum drying oven and dried at 60-80℃ for 5-8h to obtain a white powder. The white powder is then calcined at 600-1000℃ for 2.5-4.5h to obtain highly dispersible yttrium oxide powder.

2. The method for preparing yttrium oxide powder according to claim 1, characterized in that, The strong acid mentioned in step (1) is selected from one of nitric acid, hydrochloric acid, sulfuric acid or perchloric acid.

3. The method for preparing yttrium oxide powder according to claim 1, characterized in that, The yttrium source mentioned in step (1) is selected from one of yttrium oxide, yttrium chloride, yttrium acetate, yttrium sulfate, and yttrium perchlorate.

4. The method for preparing yttrium oxide powder according to claim 1, characterized in that, The mixed precipitant mentioned in step (2) can be replaced with ammonia, ammonium carbonate, ammonium bicarbonate or their complexes, and the molar ratio of the precipitant to Y³⁺ is 1:6-13; during the coprecipitation reaction in step (2), an easily decomposable mineralizing agent is added at a molar ratio of mineralizing agent to Y³⁺ of 1:7, and the easily decomposable mineralizing agent is selected from ammonium chloride or ammonium nitrate.

5. The method for preparing yttrium oxide powder according to claim 1, characterized in that, The washing process in step (3) is assisted by centrifugation, with a centrifugation speed of 2800 rpm / min and a centrifugation time of 5 min.

6. The method for preparing yttrium oxide powder according to claim 1, characterized in that, After adding the dispersant in step (4), stir magnetically for 10 minutes to ensure that the dispersant is evenly dispersed in the slurry.

7. The method for preparing yttrium oxide powder according to claim 1, characterized in that, The dispersant in step (4) is selected from one or more combinations of polyethylene glycol (PEG-6000), cetyltrimethylammonium bromide (CTAB) or CE-64.

8. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In step (5), spray granulation can be replaced by constant temperature heating and drying, where the slurry is dried at 120°C and then directly calcined.

9. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In step (6), the calcination temperature is 800℃ and the calcination time is 2.5h.

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