A method for preparing barium titanate powder

Abstract

The application belongs to the field of ceramic materials, and particularly relates to a preparation method of barium titanate powder; the preparation method comprises the following steps: S1: mixing raw materials including a titanium source, a precipitating agent and an organic solvent to obtain a mixed solution A; mixing raw materials including a barium source and water to obtain a mixed solution B; S2: mixing the mixed solution A and the mixed solution B to perform a suspension co-precipitation reaction, thereby obtaining a precursor; S3: sintering the precursor to obtain the barium titanate powder. The application mixes an organic phase containing a titanium source and a precipitating agent and a water phase containing a barium source, and performs a suspension co-precipitation reaction at the interface between the two phases when the water phase and the organic phase are mixed, thereby generating superfine barium titanate precursor; at the same time, the titanium source is in contact with water to release heat, which provides heat for the co-precipitation reaction, thereby ensuring the smooth performance of the suspension co-precipitation reaction; the method uses simple reaction equipment, and the process is stable, and the suspension co-precipitation reaction can be performed without heating.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials, specifically relating to a method for preparing barium titanate powder. Background Technology

[0002] Perovskite-type barium titanate is widely used as a raw material for functional ceramics such as piezoelectrics, optoelectronic materials, semiconductors, sensors, and multilayer ceramic capacitors. In recent years, with the continuous advancement of barium titanate preparation technology, high-purity, ultrafine, and uniformly morphologically produced barium titanate powder has become the mainstream demand in the market, especially in high-end electronic devices such as MLCCs. However, the barium titanate industry still faces some technical challenges.

[0003] Currently, barium titanate is mainly prepared using solid-phase, liquid-phase, and hydrothermal methods. The solid-phase method is the most traditional, synthesizing barium titanate by high-temperature calcination of barium and titanium oxides or carbonates. Although the process is simple and low-cost, the product is prone to particle agglomeration and uneven size distribution, making it difficult to meet the demand for high-purity, ultrafine powders. The hydrothermal method uses water as a solvent in an autoclave to synthesize barium titanate powder under high temperature and pressure conditions. Although the prepared crystals are complete and uniform, this method requires sophisticated equipment, harsh reaction conditions, and is costly, making large-scale industrial production difficult. The existing liquid-phase method involves adding inorganic salts to a precipitant to produce co-precipitation. However, due to the sequential addition of inorganic salts, the powder prepared by this method has poor particle size uniformity, and the barium-titanium ratio is difficult to control. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a method for preparing barium titanate powder.

[0005] The second objective of this invention is to provide a ceramic product.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a method for preparing barium titanate powder, comprising the following steps:

[0008] S1: Mix the raw materials including titanium source, precipitant and organic solvent to obtain mixed solution A; mix the raw materials including barium source and water to obtain mixed solution B;

[0009] S2: Mix mixed solution A and mixed solution B to carry out a suspension coprecipitation reaction to obtain the precursor;

[0010] S3: Sinter the precursor to obtain the barium titanate powder.

[0011] In some embodiments of the present invention, step S1 is as follows: adding a titanium source and a precipitant to an organic solvent to obtain a mixed solution A; mixing a barium source with water to obtain a mixed solution B. The present invention, by adding the titanium source and the precipitant to an organic solvent to obtain mixed solution A, prevents premature hydrolysis of diluted titanium tetrachloride in water, thus avoiding the generation of abnormal TiO2 in the final barium titanate powder.

[0012] In step S2 of this invention, after mixing solution A and solution B, the water in solution B and the organic solvent in solution A are dispersed into uniform droplets under vigorous stirring. Simultaneously, the titanium tetrachloride dissolved in solution A comes into contact with the pure water in solution B, releasing a large amount of heat. Without further heating, the reaction solution reaches the required reaction temperature, ensuring uniform heating, achieving the self-reaction objective, and reducing energy consumption. Under these heat conditions, the titanium source in solution A and the barium source in solution B undergo a suspension co-precipitation reaction under the action of a precipitant. Because this two-phase reaction occurs between each small droplet, the final product has a very fine particle size, yielding an ultrafine barium titanate precursor.

[0013] In some embodiments of the present invention, the titanium source includes at least one of titanium tetrachloride and tetrabutyl titanate. The titanium source in the present invention can release heat in water. When mixed solution A and mixed solution B are mixed, the titanium source releases heat upon contact with water, providing heat for the suspension coprecipitation reaction. Therefore, the preparation method of the present invention does not require an additional heat source to ensure the smooth progress of the suspension coprecipitation reaction.

[0014] In some embodiments of the present invention, the precipitant includes at least one selected from lactic acid, oxalic acid, acetic acid, and phosphoric acid. The role of the precipitant in the present invention is to undergo a suspension co-precipitation reaction with titanium and barium. If the precipitant is added to the barium source, it will react with the barium source, which is detrimental to the subsequent co-precipitation reaction. Therefore, the precipitant in the present invention needs to be added to the titanium source.

[0015] In some embodiments of the present invention, the barium source includes at least one of barium chloride, barium sulfate, and barium hydroxide.

[0016] In some embodiments of the present invention, the organic solvent includes at least one selected from toluene, benzene, and dichloromethane. The organic solvent in the present invention can dissolve the titanium source without chemically reacting with it.

[0017] In some embodiments of the present invention, the water is deionized water; in some embodiments of the present invention, the water is selected from at least one of EDI pure water and RO water. EDI pure water refers to high-purity water obtained by electrodeionization (EDI) technology, with a resistivity of up to 15-18 MΩ·cm. RO water refers to water obtained by reverse osmosis (RO) technology.

[0018] In some embodiments of the present invention, the precipitant is added as a solution containing the precipitant, wherein the mass percentage (i.e., the concentration of the precipitant) in the solution is 14-20%. In some specific embodiments of the present invention, the mass percentage of the precipitant is any value or a range formed by any combination of 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, and 20%. In some preferred embodiments of the present invention, the mass percentage of the precipitant is 15-18%. When the precipitant concentration is too low, the suspension coprecipitation reaction is too slow, and titanium tetrachloride is easily hydrolyzed to produce TiO2, resulting in impurities in the final product; when the precipitant concentration is too high, the suspension coprecipitation reaction is too fast, the generated product is too fine, and agglomeration is easily formed, leading to abnormal agglomeration in the final barium titanate powder.

[0019] In some embodiments of the present invention, the ratio of the amount of precipitant to the amount of titanium in the titanium source (i.e., precipitant / Ti) is 2 to 4; in some specific embodiments of the present invention, the ratio of the amount of precipitant to the amount of titanium in the titanium source is any value or a range formed by any two of the following: 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4. In some preferred embodiments of the present invention, the ratio of the amount of precipitant to the amount of titanium in the titanium source is 2.5 to 3.5. If the precipitant / Ti molar ratio is too low, the amount of precipitant used is insufficient, and the excess titanium source hydrolyzes into TiO2, resulting in impurity phases in the final product. If the precipitant / Ti molar ratio is too high, the amount of precipitant used is excessive, and the excess precipitant will be adsorbed on the product surface, which will seriously affect subsequent cleaning and the effect of the precipitant will also cause the product to agglomerate.

[0020] In some embodiments of the present invention, the concentration of the mixed solution B is 1–3 mol / L; in some specific embodiments of the present invention, the concentration of the mixed solution B is any value or a range formed by any combination of 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, and 3 mol / L. In some preferred embodiments of the present invention, the concentration of the mixed solution B is 1.5–2.5 mol / L. If the concentration of mixed solvent B is too low, the coprecipitation reaction will be too slow, resulting in an incomplete reaction and a low Ba / Ti ratio, which will affect the synthesis of barium titanate. If the concentration of mixed solvent B is too high, the coprecipitation reaction will be too fast, resulting in a product that is too fine and prone to agglomeration, leading to abnormal agglomeration in the final barium titanate powder.

[0021] In some embodiments of the present invention, the molar ratio of barium in mixed solution B to titanium in mixed solution A (i.e., the Ba / Ti molar ratio) is 0.99 to 1.01; in some specific embodiments of the present invention, the molar ratio of barium in mixed solution B to titanium in mixed solution A is any value or a range formed by any two of the following: 0.990, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 0.999, 1.000, 1.001, 1.002, 1.003, 1.004, 1.005, 1.006, 1.007, 1.008, 1.009, 1.01. In some preferred embodiments of the present invention, the molar ratio of barium in mixed solution B to titanium in mixed solution A is 0.995-1.005. If the Ba / Ti molar ratio is too low, Ti co-precipitation will be incomplete, and excess titanium source will hydrolyze into TiO2, resulting in impurity phases in the final product. If the Ba / Ti molar ratio is too high, too much Ba will adsorb onto the product surface, which will seriously affect subsequent cleaning and also affect the synthesis of barium titanate, resulting in poor crystallinity.

[0022] In some embodiments of the present invention, the particle size of the barium titanate powder is 150-250 nm; in some specific embodiments of the present invention, the particle size of the barium titanate powder is any value or a range formed by any two of 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, and 250 nm.

[0023] In some embodiments of the present invention, the c / a value of the barium titanate powder is >1.008; in some embodiments of the present invention, the c / a value of the barium titanate powder is 1.0081 to 1.0105; in some specific embodiments of the present invention, the c / a value of the barium titanate powder is 1.0081, 1.0082, 1.0083, 1.0084, 1.0085, 1.0086, or 1.00 The range of values ​​formed by any one of the following: 87, 1.0088, 1.0089, 1.0090, 1.0091, 1.0092, 1.0093, 1.0094, 1.0095, 1.0096, 1.0097, 1.0098, 1.0099, 1.0100, 1.0101, 1.0102, 1.0103, 1.0104, 1.0105, or any combination thereof.

[0024] In some embodiments of the present invention, the barium titanate powder (D 100 -D 50 ) / D 50 The value is less than 1; in some embodiments of the present invention, the barium titanate powder (D 100 -D 50 ) / D 50 The value is less than 0.7; in some embodiments of the present invention, the barium titanate powder (D 100 -D 50 ) / D 50 The value is 0.1 to 0.7; in some specific embodiments of the present invention, the barium titanate powder (D 100 -D 50 ) / D 50 The value is any value from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or a range of any two of these values.

[0025] In some embodiments of the present invention, the mixing is carried out by stirring.

[0026] In some embodiments of the present invention, the mixing rate is 80 to 120 rpm; in some specific embodiments of the present invention, the mixing rate is any value of 80 rpm, 90 rpm, 100 rpm, 110 rpm, 120 rpm, or a range formed by any two of them.

[0027] In some embodiments of the present invention, the mixing time is 20 to 240 min; in some specific embodiments of the present invention, the mixing time is any value or a range formed by any two of the following: 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, and 240 min.

[0028] In some preferred embodiments of the present invention, the mixing time in step S1 is 50 to 80 minutes.

[0029] In some preferred embodiments of the present invention, the mixing time in step S2 is 120-180 min.

[0030] In some embodiments of the present invention, the sintering temperature is 800–1200°C; in some embodiments, the sintering temperature is any value of 800°C, 900°C, 1000°C, 1100°C, or 1200°C, or a range formed by any two of these values. In some preferred embodiments of the present invention, the sintering temperature is 900–1000°C. If the sintering temperature is too low, it is difficult to obtain barium titanate with good crystallinity; if the sintering temperature is too high, the barium titanate grows abnormally, making it difficult to obtain fine barium titanate powder.

[0031] In some embodiments of the present invention, the sintering time is 2 to 20 hours; in other embodiments, the sintering time is any value or a range formed by any combination of 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, and 20 hours. In some preferred embodiments of the present invention, the sintering time is 6 to 15 hours. If the sintering time is too short, the production of barium titanate particles is inconsistent, resulting in poor uniformity of the final barium titanate product; if the sintering time is too long, the barium titanate particles grow abnormally, making it difficult to obtain fine barium titanate powder.

[0032] In some embodiments of the present invention, the sintering atmosphere is selected from any one of an inert atmosphere, a vacuum atmosphere, an oxidizing gas, an atmospheric atmosphere, or a mixture of any one of these with water vapor.

[0033] In some embodiments of the present invention, the preparation method further includes washing with water to remove excess impurity ions from the system. The conductivity of the washing liquid is reduced to <100 μS / cm; after washing, it is dried at 100–200°C for 5–20 hours.

[0034] A second aspect of the present invention provides a ceramic product, the material of which includes barium titanate powder prepared by the preparation method described in the first aspect of the present invention.

[0035] In some embodiments of the present invention, the ceramic product includes a piezoelectric element, an optoelectronic material, a semiconductor, an inductor, a sensor, or a multilayer ceramic capacitor.

[0036] The beneficial effects of this invention are as follows: This invention prepares an organic phase containing a titanium source and a precipitant, and an aqueous phase containing a barium source. When the aqueous phase and the organic phase are mixed, a suspension coprecipitation reaction occurs at the interface between the two phases, thereby producing an ultrafine barium titanate precursor. At the same time, the titanium source releases heat upon contact with water, providing heat for the suspension coprecipitation reaction and ensuring its stable progress. This method uses simple reaction equipment, has a stable process, and can carry out the suspension coprecipitation reaction without heating. It solves the problems of the solid-phase method where the size of barium titanate powder is limited by the size of the raw materials, making it difficult to stably produce ultrafine powder and the uneven distribution of barium and titanium ratios. It also solves the problems of low productivity and high cost caused by the complex synthesis process of the hydrothermal synthesis method, which requires the use of a high-temperature and high-pressure reactor.

[0037] The preparation method in this invention utilizes a suspension coprecipitation method, which involves a suspension coprecipitation reaction at the interface between the aqueous phase and the organic phase to prepare a barium titanate precursor, which is then sintered to obtain ultrafine barium titanate powder. Detailed Implementation

[0038] The following examples provide a more detailed description of the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are methods that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0039] Example 1

[0040] This example provides a method for preparing barium titanate powder, including the following steps:

[0041] S1: Titanium tetrachloride and lactic acid (i.e. precipitant) solution are added to toluene while stirring to obtain mixed solution A;

[0042] In the lactic acid solution, the mass percentage of lactic acid (i.e., the concentration of the precipitant) is 16%, and the ratio of the amount of lactic acid to the amount of Ti in titanium tetrachloride (i.e., precipitant / Ti) is 3; the stirring speed is 100 rpm, and the stirring time is 70 min.

[0043] S2: Add barium chloride to EDI pure water (i.e., water produced by electro-deionization water purification technology) while stirring to obtain mixed solution B;

[0044] The concentration of mixed solution B is 2 mol / L, the stirring speed is 100 rpm, and the mixing time is 70 min;

[0045] S3: The obtained mixed solution A and mixed solution B are subjected to a suspension coprecipitation reaction to obtain the barium titanate precursor;

[0046] The ratio of the amount of Ba to the amount of Ti (i.e., Ba / Ti) is 1; the mixing reaction time is 150 min, and the mixing reaction is carried out at a stirring rate of 100 rpm.

[0047] S4: Barium titanate precursor is sintered to induce a diffusion reaction between Ba and Ti, resulting in ultrafine barium titanate powder.

[0048] The sintering temperature was 950℃, the sintering time was 12h, and the sintering atmosphere was nitrogen.

[0049] S5: Remove excess impurity ions from the barium titanate powder obtained by sintering in S4 by washing. Stop washing with water when the conductivity of the washing liquid is <100μS / cm. After washing, dry at 150℃ for 15h to obtain the barium titanate powder in this example.

[0050] Examples 2-5

[0051] The preparation methods of barium titanate powder in Examples 2-5 differ from those in Example 1 only in the concentration of the precipitant. The specific parameters are shown in Table 1 below.

[0052] Examples 6-9

[0053] The preparation methods of barium titanate powder in Examples 6-9 differ from those in Example 1 only in that the precipitant / Ti ratio is different. The specific parameters are shown in Table 1 below.

[0054] Examples 10-13

[0055] The preparation methods of barium titanate powder in Examples 10-13 differ from those in Example 1 only in that the concentration of mixed solution B is different. The specific parameters are shown in Table 1 below.

[0056] Examples 14-17

[0057] The preparation methods of barium titanate powder in Examples 14-17 differ from those in Example 1 only in the Ba / Ti ratio. The specific parameters are shown in Table 1 below.

[0058] Examples 18-21

[0059] The preparation methods of barium titanate powder in Examples 18-21 differ from those in Example 1 only in that the sintering temperature is different. The specific parameters are shown in Table 1 below.

[0060] Examples 22-25

[0061] The preparation methods of barium titanate powder in Examples 22-25 differ from those in Example 1 only in that the sintering time is different. The specific parameters are shown in Table 1 below.

[0062] Comparative Examples 1-2

[0063] The only difference between the preparation methods of barium titanate powder in Comparative Examples 1 and 2 and those in Example 1 is the concentration of the precipitant. The specific parameters are shown in Table 1 below.

[0064] Comparative Examples 3-4

[0065] The preparation methods of barium titanate powder in Comparative Examples 3 and 4 differ from those in Example 1 only in that the precipitant / Ti ratio is different. The specific parameters are shown in Table 1 below.

[0066] Comparative Examples 5-6

[0067] The only difference between the preparation methods of barium titanate powder in Comparative Examples 5 and 6 and those in Example 1 is that the concentration of mixed solution B is different. The specific parameters are shown in Table 1 below.

[0068] Comparative Examples 7-8

[0069] The preparation methods of barium titanate powder in Comparative Examples 7 and 8 differ from those in Example 1 only in the Ba / Ti ratio. The specific parameters are shown in Table 1 below.

[0070] Comparative Examples 9-10

[0071] The only difference between the preparation methods of barium titanate powder in Comparative Examples 9 and 10 and those in Example 1 is the sintering temperature. The specific parameters are shown in Table 1 below.

[0072] Comparative Examples 11-12

[0073] The preparation methods of barium titanate powder in Comparative Examples 11-12 differ from those in Example 1 only in that the sintering time is different. The specific parameters are shown in Table 1 below.

[0074] Table 1. Preparation parameters of the preparation methods in Examples 1-25 and Comparative Examples 1-12

[0075]

[0076]

[0077] Performance testing

[0078] The properties of the barium titanate powders prepared in Examples 1-25 and Comparative Examples 1-12 were tested according to the following test methods. The specific test methods are as follows:

[0079] a) The particle size of barium titanate powder, taking a standard of 150-250 nm as an example;

[0080] Test method: Barium titanate powder was prepared on conductive adhesive, and the morphology of the powder was photographed using FE-SEM. The particle size of the final barium titanate powder was obtained by statistically analyzing the average diameter of more than 600 particles in 3 images.

[0081] b) The Ba / Ti molar ratio should be between 0.99 and 1.01.

[0082] Test method: Weigh 0.3g of barium titanate powder and add lithium tetraborate, lithium metaborate and other co-solvents, melt at 1000℃ to form a glass slide sample to be tested, and test the Ba / Ti ratio of barium titanate powder by X-ray fluorescence spectroscopy (XRF).

[0083] c) The crystallinity of barium titanate powder meets the standard of c / a > 1.0080;

[0084] Test method: Weigh 0.5g of barium titanate powder, flatten the sample with a glass slide, and test the crystallinity of the barium titanate powder by X-ray diffraction (XRD).

[0085] d) The dispersibility of barium titanate powder meets the standard of A < 1;

[0086] Test method: Barium titanate powder was dispersed in a 0.5% sodium hexametaphosphate solution to prepare a solution with a solid content of 0.1%. The particle size distribution of the obtained barium titanate was then measured using a Malvern laser particle size analyzer 2000. Dispersibility A = (D 100 -D 50 ) / D 50 .

[0087] The performance data of barium titanate powder obtained according to the above test method are shown in Table 2 below.

[0088] Table 2 Properties of Barium Titanate Powder

[0089]

[0090]

[0091] As shown in Table 2, Examples 1-25 of this invention, by controlling the concentration of the precipitant, the molar ratio of the precipitant to Ti, the concentration of the mixed solution B, the molar ratio of Ba / Ti, and the sintering parameters during the preparation process, resulted in barium titanate powder with a particle size of 150-250 nm, a Ba / Ti molar ratio of 1 ± 0.01, a c / a value > 1.0080, and an A value < 1. This powder exhibits high purity, ultrafine texture, and uniform morphology, meeting the requirements of high-end electronic devices such as MLCCs for barium titanate powder. The following analysis is based on specific comparative examples:

[0092] When the precipitant concentration is below 14% (e.g., Comparative Example 1), the suspension coprecipitation reaction is too slow, and titanium tetrachloride is easily hydrolyzed to produce TiO2. During calcination, the TiO2 produced will generate large particles, resulting in excessively large barium titanate particles, a high product A value, and failure to meet standards. When the precipitant concentration is above 20% (e.g., Comparative Example 2), the suspension coprecipitation reaction is too fast, the generated product is too fine, and the product is prone to agglomeration, resulting in abnormal agglomeration of the final barium titanate powder, a high product A value, and a low c / a ratio, which also fails to meet standards.

[0093] When the precipitant / Ti molar ratio is less than 2 (e.g., Comparative Example 3), the amount of precipitant is insufficient. Excess titanium source in the reaction system hydrolyzes into TiO2, and the TiO2 particles grow abnormally during calcination, resulting in excessively large product particle size and a high A value, which is unqualified. When the precipitant / Ti molar ratio is greater than 4 (e.g., Comparative Example 4), the amount of precipitant is excessive. Excess precipitant in the reaction system will be adsorbed on the surface of the barium titanate product, which seriously affects the subsequent cleaning. At the same time, the effect of the precipitant will also cause the product to agglomerate due to excessively fine particles, resulting in an unqualified product A value and a low c / a value.

[0094] When the concentration of mixed solution B is below 1 mol / L (i.e., Comparative Example 5), the suspension coprecipitation reaction is too slow, resulting in incomplete reaction and a low Ba / Ti molar ratio, which affects the synthesis of barium titanate. Furthermore, during calcination, there is insufficient Ba diffusion to Ti, leading to abnormal Ti growth and a high A value in the product, making it unqualified. When the concentration of solvent B is above 3 mol / L (i.e., Comparative Example 6), the suspension coprecipitation reaction is too fast, and the generated product agglomerates due to its excessively fine particle size, resulting in abnormal agglomerated particles in the final barium titanate powder. This leads to a high A value and a low c / a ratio in the product, making it unqualified.

[0095] When the Ba / Ti molar ratio is below 0.99 (i.e., Comparative Example 7), the Ba / Ti molar ratio is too low, Ti co-precipitation is incomplete, and excess titanium source hydrolyzes into TiO2. During calcination, TiO2 particles grow abnormally, resulting in larger particles and excessively large product particles. The product A value is too high, making it unqualified. When the Ba / Ti molar ratio is above 1.01 (i.e., Comparative Example 8), excessive Ba will adsorb on the product surface, which seriously affects subsequent cleaning. Excessive Ba will also affect the synthesis of barium titanate, resulting in poor crystallinity, excessively high product A value, and low c / a ratio, making it unqualified.

[0096] When the sintering temperature is below 800℃ (i.e., Comparative Example 9), it is difficult to obtain barium titanate with good crystallinity. The product grains are too fine and unqualified, and the c / a ratio is too low and unqualified. When the sintering temperature is above 1200℃ (i.e., Comparative Example 10), barium titanate grows abnormally, making it difficult to obtain fine barium titanate powder. The product A value is too high and unqualified.

[0097] When the sintering time is less than 2 hours (e.g., Comparative Example 11), the sintering time is too short, the production of barium titanate particles is inconsistent, the uniformity of the final barium titanate product is poor, the product grains are too fine and unqualified, and the c / a value is too low and unqualified. When the sintering time is more than 20 hours (e.g., Comparative Example 12), the sintering time is too long, the barium titanate grows abnormally, it is difficult to obtain fine barium titanate powder, the product A value is too high and unqualified.

[0098] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing barium titanate powder, characterized in that: Includes the following steps: S1: Raw materials including a titanium source, a precipitant, and an organic solvent are mixed to obtain mixed solution A; raw materials including a barium source and water are mixed to obtain mixed solution B; the precipitant is lactic acid; the organic solvent includes at least one of toluene, benzene, and dichloromethane; the molar ratio of the precipitant to the molar ratio of titanium in the titanium source is 2-4; the titanium source includes at least one of titanium tetrachloride and tetrabutyl titanate; The precipitant is added in the form of a solution containing the precipitant, wherein the mass percentage of the precipitant in the solution is 14-20%. The concentration of the mixed solution B is 1~3 mol / L; S2: Mix mixed solution A and mixed solution B to carry out a suspension coprecipitation reaction to obtain the precursor; S3: Sinter the precursor to obtain the barium titanate powder.

2. The method for preparing barium titanate powder according to claim 1, characterized in that: The barium source includes at least one of barium chloride, barium sulfate, and barium hydroxide.

3. The method for preparing barium titanate powder according to claim 1, characterized in that: The molar ratio of barium in the mixed solution B to titanium in the mixed solution A is 0.99 to 1.

01.

4. The method for preparing barium titanate powder according to any one of claims 1 to 3, characterized in that: The barium titanate powder has at least one of the following characteristics: (a1) The particle size of the barium titanate powder is 150-250 nm; (a2) The c / a value of the barium titanate powder is >1.008; (a3) The (D100-D50) / D50 value of the barium titanate powder is less than 1.

5. The method for preparing barium titanate powder according to any one of claims 1 to 3, characterized in that: The mixing rate is 80~120 rpm; And / or, the mixing time is 20~240 min.

6. The method for preparing barium titanate powder according to any one of claims 1 to 3, characterized in that: The sintering temperature is 800~1200℃; And / or, the sintering time is 2 to 20 hours.

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