Barium titanate powder, and preparation method and application thereof

Abstract

The application belongs to the field of nano ceramic powder preparation, discloses a barium titanate powder and a preparation method and application thereof, and aims to solve the technical problems of large particle size, wide distribution and poor dispersibility of the barium titanate powder, and the steps are as follows: (1) preparing a barium salt solution; (2) taking anatase titanium dioxide obtained by calcining titanate nanotubes as a titanium source, adding the titanium source into the barium salt solution, and obtaining a barium titanate precursor solution; (3) performing hydrothermal reaction on the precursor solution; (4) performing filtration, washing, drying and grinding to obtain the barium titanate powder. The barium titanate prepared by the application has the characteristics of small particle size, narrow distribution and good dispersibility; meanwhile, the reaction can avoid using a large amount of mineralizer, the method has low cost, good safety, simple process, and can realize large-scale production of the powder, and meets the development requirements of subsequent small-size multilayer ceramic capacitor products.

Description

Technical Field

[0001] This invention belongs to the field of nano-ceramic powder preparation, specifically referring to a barium titanate powder, its preparation method, and its application. Background Technology

[0002] With the rapid development of the 5G communication era, multilayer ceramic capacitors (MLCCs), as the most important passive devices, are gradually developing towards miniaturization, high performance, and high reliability. The key to achieving MLCC miniaturization lies in the nano-sizing of barium titanate ceramic powder. The reliability and high performance of devices often depend on the structure, morphology, and other related properties of the powder material. Therefore, preparing small-sized, highly dispersed, and highly tetragonal barium titanate powder is crucial to meeting the requirements of MLCC development trends.

[0003] Among numerous preparation methods, the hydrothermal method has been widely studied due to its controllable preparation conditions, high powder purity, and small particle size. It is considered one of the most promising methods for preparing high-performance powders and promoting the rapid development of high-end MLCCs. During the hydrothermal reaction, the particle size and dispersibility of the titanium source precursor itself significantly influence the dissolution, nucleation, and particle growth rate, ultimately affecting the particle size, dispersibility, and tetragonal phase content of the barium titanate powder. For example, patent CN117125737A discloses a low-cost method for preparing highly tetragonal nano-barium titanate powder. This method uses ordinary titanium dioxide as a titanium source, adding it to a barium salt solution and conducting a hydrothermal reaction in the presence of an inorganic alkali. However, the presence of this inorganic alkali necessitates subsequent cleaning with acetic acid and ethanol, which is detrimental to scale-up production and subsequent performance. Furthermore, the product has a large average particle size and poor dispersibility. Therefore, selecting a suitable titanium source precursor is crucial for preparing high-quality powders.

[0004] Maxim et al. prepared hollow cubic barium titanate materials via hydrothermal reaction using sodium titanate nanotubes as the titanium source and BaCl2·2H2O as the barium source. This structure and morphology are unsuitable for use as raw materials in MLCCs. Titanate nanotubes are tubular nanomaterials, and their tubular morphology and excellent reactivity have led to their application in adsorption and photocatalysis. Previous studies using acid-treated sodium titanate nanotubes (NTA) as the titanium source for hydrothermal preparation of barium titanate nanoparticles revealed that due to the high reactivity of NTA, the initial reaction stage resulted in a mixed morphology of broken tubular structures and small barium titanate nuclei, leading to inconsistent nucleation rates and a wide particle size distribution. Therefore, finding a suitable treatment method to maintain a consistent nucleation rate during the reaction is crucial for preparing barium titanate powders with small particle size, narrow size distribution, and good dispersibility. Summary of the Invention

[0005] To address the technical problems of large particle size, wide distribution, and poor dispersibility of barium titanate powder in existing technologies, this invention proposes a barium titanate powder, its preparation method, and its application, which produces small-sized, highly dispersed barium titanate powder; moreover, the preparation process does not require the addition of mineralizing agents and is simple.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is implemented as follows:

[0007] A method for preparing barium titanate powder, comprising the following steps:

[0008] (1) Prepare a barium salt solution of a certain concentration, heat to dissolve, and cool down after complete dissolution;

[0009] (2) Weigh the titanium source according to a certain barium-titanium molar ratio, add it to the barium salt solution, and emulsify and shear at high speed to obtain the barium titanate precursor solution.

[0010] (3) The barium titanate precursor solution was transferred to a high-temperature reactor and hydrothermally reacted to obtain a barium titanate suspension.

[0011] (4) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0012] In step (1), the barium salt is Ba(OH)2·8H2O, the solvent is deionized water, and the concentration of the barium salt solution is 2-3 mol / L.

[0013] In step (1), the temperature for heating and dissolving the barium salt solution is 70-90℃, and after complete dissolution, the temperature is lowered to 40-50℃.

[0014] In step (2), the titanium source is anatase titanium dioxide formed by treating titanate nanotubes (NTA) at 400-700℃ for 0.5-8h.

[0015] In step (2), the barium / titanium molar ratio is (1.0-1.2):1.

[0016] The temperature of the hydrothermal reaction in step (3) is 160-200℃ and the time is 8-24h.

[0017] Barium titanate powder prepared by the above preparation method.

[0018] The above-mentioned barium titanate powder is used in multilayer ceramic capacitors.

[0019] The beneficial effects of this invention are:

[0020] (1) In this invention, after treating titanate nanotubes at different temperatures (400-700℃), the one-dimensional tubular structure is gradually destroyed, forming well-dispersed nanoparticles of 20-50 nm. Simultaneously, the orthorhombic crystal system is transformed into anatase titanium dioxide as the titanium source. By controlling the morphology, crystallinity, and dispersibility of the precursor, the reactivity is improved, and the dissolution-nucleation rate during the reaction is kept relatively consistent, thus ensuring the preparation of highly dispersible powder with uniform particle size distribution. Using the above method and formulation, barium titanate powder with an average particle size of 60-100 nm and a tetragonal phase crystal structure can be obtained. The prepared barium titanate particles have complete morphology and uniform dispersion, meeting the requirements of modern ceramic capacitor miniaturization.

[0021] (2) This invention provides a high-concentration alkaline environment for the reaction by increasing the concentration of the barium source Ba(OH)₂·8H₂O. Furthermore, it uses titanium dioxide processed from titanate nanotubes as the titanium source, which exhibits high reactivity and good dispersibility. This combination avoids the need for large amounts of alkaline mineralizing agents, reducing the subsequent extensive water washing process and preventing trace amounts of alkaline or alkaline earth metal ions from remaining in the barium titanate matrix. This satisfies the purity requirements of MLCC raw materials and increases reaction yield and production efficiency. The method is simple, has low preparation costs, and is suitable for large-scale production. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The XRD pattern (a) and SEM image (b) of the titanium dioxide source prepared in Example 1 of this invention are shown.

[0024] Figure 2 This is a SEM image of the barium titanate powder prepared in Example 1 of the present invention.

[0025] Figure 3 This is a particle size distribution diagram of the barium titanate powder prepared in Example 1 of the present invention.

[0026] Figure 4 The image shows the XRD pattern of barium titanate powder prepared in Example 1 of this invention.

[0027] Figure 5 This is a SEM image of the barium titanate powder prepared in Comparative Example 1 of this invention.

[0028] Figure 6This is a particle size distribution diagram of the barium titanate powder prepared in Comparative Example 1 of the present invention.

[0029] Figure 7 The image shows the XRD pattern of barium titanate powder prepared in Comparative Example 1 of this invention.

[0030] Figure 8 This is a SEM image of the barium titanate powder prepared in Comparative Example 2 of this invention. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] The titanate nanotubes used in this invention are prepared as follows: TiO2 is dispersed in 80 mL of 10 M NaOH solution, stirred evenly, and then placed in a polytetrafluoroethylene hydrothermal reactor. The reactor is reacted at 120 °C for 24 h to prepare Na2Ti2O5·H2O. The Na2Ti2O5·H2O is then washed with water until pH = 10, and then acid-washed with HCl solution (pH = 1.0) until pH = 1.2. The mixture is stirred for 4-5 h, and then washed again with water to remove Cl. - After neutralization, filter, and finally dry in a vacuum oven at 60℃. The resulting product is H2Ti2O5·H2O, abbreviated as NTA.

[0033] Example 1

[0034] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0035] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0036] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0037] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0038] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0039] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0040] Figure 1 This is a structural characterization diagram of the titanium dioxide source used in this embodiment. From... Figure 1 The XRD pattern shows that the titanium dioxide source has anatase crystal structure. Figure 1 The b SEM image shows that the titanium dioxide particles are composed of small particles of 20-50 nm, and the particles are evenly dispersed.

[0041] Figure 2 This is a SEM image of the barium titanate powder prepared in this embodiment. Figure 3 This is a particle size distribution diagram. From... Figure 2 and 3 As can be seen from the data, the barium titanate powder prepared under this process has an average particle size of about 98 nm, with uniform particle size and a narrow distribution. Figure 4 The XRD pattern of the barium titanate powder prepared in this embodiment shows that the characteristic peaks of pure barium titanate are obtained, with no impurity peaks. After refining the XRD data, its c / a value is 1.0073, indicating a high tetragonal phase content.

[0042] Example 2

[0043] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0044] (1) Weigh a certain amount of titanate nanotubes and place them in a muffle furnace. Heat treat them at 500℃ for 4 hours to obtain anatase titanium dioxide.

[0045] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 90℃ until completely dissolved, and then let it cool naturally to 45℃.

[0046] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0047] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0048] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0049] Example 3

[0050] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 400℃ for 8 hours to obtain anatase titanium dioxide.

[0051] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0052] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0053] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0054] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0055] Example 4

[0056] (1) Weigh a certain amount of titanate nanotubes and place them in a muffle furnace. Heat treat them at 700℃ for 0.5h to obtain anatase titanium dioxide.

[0057] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0058] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0059] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0060] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0061] Example 5

[0062] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0063] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0064] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2.4M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0065] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0066] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0067] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0068] Example 6

[0069] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0070] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0071] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2.8M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0072] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0073] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0074] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0075] Example 7

[0076] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0077] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0078] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 3.0M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0079] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0080] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0081] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0082] Example 8

[0083] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0084] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0085] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0086] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0087] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0088] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0089] Example 9

[0090] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0091] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0092] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0093] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.1:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0094] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0095] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0096] Example 10

[0097] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0098] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0099] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0100] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.2:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0101] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0102] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0103] Example 11

[0104] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0105] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0106] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0107] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0108] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 160°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0109] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0110] Example 12

[0111] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0112] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0113] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0114] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0115] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 180°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0116] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0117] Example 13

[0118] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0119] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0120] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0121] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0122] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 8 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0123] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0124] Example 14

[0125] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0126] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0127] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0128] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0129] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 16 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0130] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0131] Example 15

[0132] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0133] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0134] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 70℃ until completely dissolved, and then let it cool naturally to 40℃.

[0135] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0136] (3) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0137] (4) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0138] Example 16

[0139] The preparation method of barium titanate powder in this embodiment includes the following steps:

[0140] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0141] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 90℃ until completely dissolved, and then let it cool naturally to 50℃.

[0142] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0143] (3) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0144] (4) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0145] Comparative Example 1

[0146] The preparation method of the barium titanate powder in this comparative example includes the following steps:

[0147] (1) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0148] (2) Add titanate nanotubes to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain barium titanate precursor solution.

[0149] (3) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0150] (4) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0151] Figure 5 This is a SEM image of the barium titanate powder prepared in this comparative example. Figure 6 This is a particle size distribution diagram. From... Figure 5 and 6 As can be seen, the barium titanate powder prepared under this preparation process has an average particle size between 90-130 nm and an average particle size of 108 nm. The particle size distribution is relatively wide, and its agglomeration coefficient is 1.72. Compared with Example 1, the sample size is not uniform and agglomeration is serious. Figure 7 The XRD pattern of the barium titanate powder prepared in this embodiment shows that the characteristic peaks of pure barium titanate are obtained, with no impurity peaks. After refining the XRD data, its c / a value is 1.0059, and the tetragonal phase content is lower than that in Example 1.

[0152] Comparative Example 2

[0153] The preparation method of the barium titanate powder in this comparative example includes the following steps:

[0154] (1) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0155] (2) Add commercially available ordinary titanium dioxide to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain barium titanate precursor solution.

[0156] (3) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0157] (4) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0158] Figure 8The image shows a SEM image of the barium titanate powder prepared in this comparative example. Figure 8 As can be seen from the data, the barium titanate powder prepared under this process has a wide particle size distribution, ranging from 100 to 500 nm.

[0159] Comparative Example 3

[0160] The preparation method of the barium titanate powder in this comparative example includes the following steps:

[0161] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0162] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 1.6M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0163] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0164] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0165] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0166] Comparative Example 4

[0167] The preparation method of barium titanate powder in this comparative example includes the following steps:

[0168] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0169] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 3.2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0170] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0171] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 200°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0172] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0173] Because of the high concentration of barium salt, the corresponding concentration of titanium source is also high, which means that titanium dioxide powder cannot be completely dispersed in the system and cannot be effectively dispersed. The sample viscosity is high, making it impossible to stir and the reaction cannot proceed.

[0174] Comparative Example 5

[0175] The preparation method of barium titanate powder in this comparative example includes the following steps:

[0176] (1) A certain amount of titanate nanotubes were weighed and placed in a muffle furnace and heat-treated at 600℃ for 2 hours to obtain anatase titanium dioxide.

[0177] (2) Weigh Ba(OH)2·8H2O into a beaker, add deionized water, prepare a 2M Ba(OH)2·8H2O solution, stir and heat to 85℃ until completely dissolved, and then let it cool naturally to 45℃.

[0178] (3) Add the titanium source prepared in step (1) to the prepared Ba(OH)2·8H2O solution, control the Ba / Ti molar ratio at 1.06:1, and shear at 1000 rpm for 10 min to obtain the barium titanate precursor solution.

[0179] (4) The barium titanate precursor solution was transferred to a high-pressure reactor and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, a barium titanate suspension was obtained.

[0180] (5) The barium titanate suspension was filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

[0181] Performance Testing and Results Analysis

[0182] The prepared barium titanate powder was subjected to performance testing. The grain size was observed using scanning electron microscopy (SEM), and the cumulative particle size distribution percentage D was obtained using a laser particle size analyzer. 50 The specific surface area equivalent particle size D was obtained by testing and calculation using a specific surface area analyzer. BET Through the formula AF=D 50 / D BETThe agglomeration coefficient of the powder is calculated, and the degree of dispersion of the powder is often represented by the agglomeration coefficient AF. The closer the agglomeration coefficient AF is to 1, the better the dispersion of the powder. Higher dispersion can reduce the generation of pores during the later sintering process, which is conducive to improving the density of ceramics. The tetragonality c / a of the powder is obtained by XRD testing and fine refining.

[0183] (1) The effects of titanate nanotubes or different heat treatments and commercially available ordinary titanium dioxide on the properties of barium titanate powder are shown in Table 1.

[0184] Table 1. Effects of titanate nanotubes, different heat treatments, and commercially available ordinary titanium dioxide on the properties of barium titanate powder.

[0185]

[0186] As can be seen from Table 1, barium titanate prepared from titanium dioxide obtained by calcining NTA at 600℃ for 2h has smaller particle size, better dispersibility and higher tetragonal phase content.

[0187] (2) The effect of the concentration of barium salt solution on the properties of barium titanate powder is shown in Table 2.

[0188] Table 2. Effect of barium salt solution concentration on the properties of barium titanate powder

[0189]

[0190] As shown in Table 2, increasing the concentration of barium salt provides a highly alkaline environment for the reaction system, which accelerates the nucleation rate of barium titanate in the initial stage of the reaction and promotes the growth of crystal nuclei in the later stage, resulting in a gradual increase in particle size. Simultaneously, the highly alkaline environment facilitates the removal of hydrogen ions during the reaction. + More thorough, lattice OH - The reduction promotes the transformation of powder to the tetragonal phase, showing a trend of gradually increasing tetragonality; the agglomeration coefficient AF shows that it exhibits good dispersibility when the barium salt concentration in Example 1 is 2M; comprehensive comparison shows that the barium salt concentration of 2M is the optimal reaction concentration.

[0191] (3) The effect of Ba / Ti molar ratio on the properties of barium titanate powder is shown in Table 3.

[0192] Table 3 Effect of Ba / Ti molar ratio on the properties of barium titanate powder

[0193] Examples / Comparative Examples Ba / Ti molar ratio Average particle size AF c / a Example 1 1.06：1 98nm 1.03 1.0073 Example 8 1：1 96nm 1.53 1.0073 Example 9 1.1：1 99nm 1.27 1.0075 Example 10 1.2：1 100nm 1.40 1.0076

[0194] As shown in Table 3, increasing the Ba / Ti ratio provides a greater driving force for subsequent particle growth, leading to gradual particle fusion and an increase in particle size, but with minimal overall impact on particle size. Simultaneously, the Ba / Ti ratio can regulate the alkaline environment of the reaction; as the Ba / Ti ratio gradually increases, it can effectively eliminate some defects and promote the synthesis of high tetragonal barium titanate powder. Furthermore, when the Ba / Ti ratio is appropriately increased to 1.06, it exhibits good dispersibility, representing the optimal barium-titanium ratio.

[0195] (4) The effect of hydrothermal reaction temperature on the properties of barium titanate powder is shown in Table 4.

[0196] Table 4. Effect of hydrothermal reaction temperature on the properties of barium titanate powder

[0197] Examples / Comparative Examples reaction temperature Average particle size AF c / a Example 1 200℃ 98nm 1.03 1.0073 Example 11 160℃ 81nm 1.53 1.0061 Example 12 180℃ 91nm 1.48 1.0073 Comparative Example 5 220℃ 102nm 1.26 1.0074

[0198] As shown in Table 4, increasing the reaction temperature provides sufficient driving force for particle nucleation and growth, causing particles to gradually grow larger and exhibiting a trend of increasing particle size. Furthermore, higher temperatures promote the transformation of particles from angular to tetragonal, gradually increasing tetragonality. At 200℃, the powder exhibits a smaller agglomeration coefficient, good dispersibility, and a higher tetragonal phase content, representing the optimal reaction temperature.

[0199] (5) The effect of hydrothermal reaction time on the properties of barium titanate powder is shown in Table 5.

[0200] Table 5. Effect of hydrothermal reaction time on the properties of barium titanate powder

[0201] Examples / Comparative Examples reaction time Average particle size AF c / a Example 1 24h 98nm 1.03 1.0073 Example 13 8h 68nm 1.51 1.0063 Example 14 16h 78nm 1.33 1.0067

[0202] As can be seen from Table 5, extending the reaction time allows the particles to gradually develop fully, prolonging the growth stage and increasing the particle size. At the same time, extending the reaction time causes the c-axis in the crystal structure to gradually lengthen and the a-axis to gradually shorten, showing a trend of gradually increasing tetragonality.

[0203] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing barium titanate powder, characterized in that, The steps are as follows: (1) Prepare a barium salt solution with a concentration of 2-3 mol / L using Ba(OH)2·8H2O as the barium salt; (2) Using anatase titanium dioxide obtained by heat treatment of titanate nanotubes as the titanium source, the titanium source is weighed according to the barium-titanium molar ratio and added to the barium salt solution. High-speed emulsification and shearing are performed to obtain barium titanate precursor solution. The heat treatment temperature is 400-700℃ and the time is 0.5-8h. (3) The barium titanate precursor solution obtained in step (2) is subjected to hydrothermal reaction at 160-200℃ for 8-24h to obtain barium titanate suspension; (4) The barium titanate suspension obtained in step (3) is filtered, washed with deionized water, dried and ground to obtain barium titanate powder.

2. The method for preparing barium titanate powder according to claim 1, characterized in that, The process of preparing the barium salt solution in step (1) is as follows: dissolve Ba(OH)2·8H2O in deionized water, heat to 70-90℃ to dissolve, and then cool to 40-50℃ after complete dissolution.

3. The method for preparing barium titanate powder according to claim 2, characterized in that, In step (2), the barium-titanium molar ratio is (1.0-1.2):

1.

4. Barium titanate powder prepared by the preparation method according to claim 1.

5. The application of the barium titanate powder according to claim 4 in multilayer ceramic capacitors.

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