A barium titanate nanopowder and a preparation method thereof

Abstract

The present invention discloses a barium titanate nano-powder and a preparation method thereof, belonging to the technical field of dielectric material nano-powders. The preparation method of the present invention includes the following steps: (1) Mix barium tartrate and metatitanic acid to obtain a mixed material, add water and stir well, add a dispersant and an alkali solution to the obtained mixed slurry, and perform ball milling treatment to obtain a mixed slurry; (2) Wash, filter, dry and grind the obtained mixed slurry in sequence to obtain a precursor powder; (3) Calcinate the obtained precursor powder at a high temperature, and after grinding, obtain a barium titanate nano-powder. The barium titanate nano-powder prepared by the present invention has a high content of tetragonal phase, excellent performance, less agglomeration, small particle size (50 - 200 nm), good uniformity and dispersibility, and has good practical application value. At the same time, the preparation process is simple, the operation is simple and easy, the requirements for equipment are low, the energy consumption is low, the production cost is low, it is safe and pollution-free, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of dielectric material nanopowders, and in particular relates to barium titanate nanopowder and a preparation method thereof. Background Art

[0002] Barium titanate (BTO) is a strong dielectric compound material. Due to its high dielectric constant and low dielectric loss, it is widely used in the electronic ceramics industry, earning it the nickname "the pillar of the electronic ceramics industry." It is particularly popular in multilayer ceramic capacitors (MLCCs). With the advancement of technology, MLCCs are no longer able to meet consumer demand, leading to a gradual shift towards miniaturization. Research is currently underway to achieve this while simultaneously reducing costs and increasing the capacitance of ceramics. The most significant factor influencing ceramic performance is the powder itself. As the primary raw material for MLCCs, BTO powders with reduced particle size, excellent uniformity, and good dispersion are crucial to meeting the demands of miniaturization. This creates new challenges for raw material research. Current BTO powders used in MLCCs include BT-04 (average particle size 400nm), BT-03 (average particle size 300nm), BT-025 (average particle size 250nm), and BT-015 (average particle size 150nm). The smaller and more uniformly distributed the particle size of barium titanate powder material, the higher the price, such as BT-015. In order to meet market demand, it is necessary to continuously research new methods and improve production processes in order to produce higher quality barium titanate powder materials.

[0003] At present, the preparation technology of barium titanate powder has become mature. To meet the production demand, the main methods are solid-phase method and hydrothermal method, and large-scale production has been achieved, but the two methods have their own advantages and disadvantages. The barium titanate powder synthesized by the hydrothermal method has a small particle size, good particle dispersion and uniformity, but the equipment requirements are high. At the same time, the powder is prepared under high pressure, which poses a safety hazard and limits the promotion and application of this method. Although the traditional production method, the solid-phase method, produces powders with larger particle size, poor uniformity and dispersibility, as a relatively mature process, compared with the hydrothermal method, it has low equipment requirements, low energy consumption, and low cost, and can produce low-end and mid-range MLCC products in large quantities. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for preparing barium titanate nanopowder to solve the problems of large particle size, poor uniformity and dispersibility of barium titanate nanopowder prepared by traditional solid phase method.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing barium titanate nanopowder comprises the following steps:

[0007] (1) Mix barium tartrate and metatitanic acid to obtain a mixed material, add water and stir well. Add a dispersant to the obtained mixed material liquid, and add an alkali solution to adjust the pH value of the mixed material liquid. After ball milling treatment, a mixed slurry is obtained;

[0008] (2) Wash, filter by suction, dry and grind the obtained mixed slurry in sequence to obtain a precursor powder;

[0009] (3) Calcinate the obtained precursor powder at high temperature, and after grinding, barium titanate nano powder is obtained.

[0010] Further, in step (1), the molar ratio of barium tartrate to metatitanic acid is 1-1.5:1.

[0011] Further, in step (1), the dispersant is one or a combination of more of alcohol ether phosphate, lauroyl glutamate, fatty alcohol polyoxyethylene ether, cetyltrimethylammonium bromide; the ratio of alcohol ether phosphate to cetyltrimethylammonium bromide is 1:2-3; the ratio of lauroyl glutamate to fatty alcohol polyoxyethylene ether is 0.2-0.4:1; the ratio of lauroyl glutamate to alcohol ether phosphate is 8-10:1; the ratio of lauroyl glutamate, alcohol ether phosphate and fatty alcohol polyoxyethylene ether is 3-4:1-2:1.

[0012] Further, in step (1), the dosage of the dispersant is 0.15-3wt%.

[0013] Further, in step (1), the alkali solution is one or a combination of more of ammonia water, ethylenediamine, sodium hydroxide, potassium hydroxide; the ratio of ammonia water to ethylenediamine is 1:1-2; the ratio of sodium hydroxide to potassium hydroxide is 1:1-2; the ratio of ammonia water to potassium hydroxide is 1:1-2; the ratio of ethylenediamine, ammonia water and sodium hydroxide is 1:1-2:2-3.

[0014] Further, in step (1), the dosage of the alkali solution is 0.1-0.5wt%; the pH value of the mixed material liquid is 3.8-7.5.

[0015] Further, in step (1), the mass ratio of the ball milling medium used in the ball milling treatment to the mixed material is 20-50:1, and the ball milling time is 0.5-24h; the ball milling medium is a zirconia sphere with a diameter of 0.5-2mm.

[0016] Further, in step (3), the temperature of the high-temperature calcination is 600-1100°C, and the time is 0.5-12h.

[0017] Barium titanate nanopowder prepared by the above-mentioned preparation method of barium titanate nanopowder.

[0018] Furthermore, the particle size of the barium titanate nanopowder is 50 to 200 nm.

[0019] The preparation principle of the barium titanate nanopowder of the present invention is as follows:

[0020] Since barium tartrate is slightly soluble in water, it continuously dissolves and precipitates during the ball milling process. During this process, within a certain pH range, since the dispersant is a surfactant such as alcohol ether phosphate, under the action of the surfactant, the newly precipitated nano-barium tartrate is evenly wrapped on the surface of the metatitanic acid, forming a precursor with a uniform ideal structure. The precursor is calcined at high temperature to obtain a uniform mixture of nano-barium carbonate and titanium dioxide, which is conducive to the formation of small-particle barium titanate powder.

[0021] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0022] 1. The present invention adopts a solid-phase method to prepare barium titanate nanopowder, using barium tartaric acid as a barium source, metatitanic acid as a titanium source, a surfactant as a dispersant, and adding an alkaline solution to adjust the pH value of the mixed liquid. After ball milling and high-temperature calcination, the barium titanate nanopowder is obtained. The powder has excellent performance, small particle size, good uniformity and dispersibility.

[0023] 2. The barium titanate nanopowder prepared by the present invention has a high tetragonal phase content (c / a ≧ 1.0080), less particle agglomeration, and a small particle size (50 to 200 nm). Compared with the barium titanate powder prepared by the traditional solid-phase method (particle size of 400 nm to 1 μm), the barium titanate nanopowder of the present invention has better uniformity and dispersibility, has good practical application value, and is more suitable for application in multilayer ceramic capacitors.

[0024] 3. The present invention adopts a solid phase method to prepare barium titanate nanopowder, which has a simple preparation process, is easy to operate, has low equipment requirements, low energy consumption, low production cost, is safe and pollution-free, and is suitable for mass production in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 These are the XRD patterns of the barium titanate nanopowders prepared in Examples 1-6 respectively.

[0026] Figure 2 This is the SEM image of the barium titanate nanopowder prepared in Example 1.

[0027] Figure 3 This is the SEM image of the barium titanate nanopowder prepared in Example 2.

[0028] Figure 4This is the SEM image of the barium titanate nanopowder prepared in Example 3.

[0029] Figure 5 This is the SEM image of the barium titanate nanopowder prepared in Example 4.

[0030] Figure 6 This is the SEM image of the barium titanate nanopowder prepared in Example 5.

[0031] Figure 7 This is the SEM image of the barium titanate nanopowder prepared in Example 6. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below through examples. These examples are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0033] Example 1

[0034] Preparation of barium titanate nanopowder:

[0035] According to the molar ratio of barium tartaric acid to titanic acid being 1:1, barium tartaric acid and titanic acid are weighed and placed in a ball mill for mixing to obtain a mixture, water is added and fully stirred, 0.15wt% of alcohol ether phosphate and 0.35wt% of hexadecyltrimethylammonium bromide are added to the obtained mixed liquid, and 0.1wt% of ammonia water and 0.2wt% of ethylenediamine are added to adjust the pH value of the mixed liquid to 3.8, and then zirconium dioxide spheres are added according to the mass ratio of ball milling medium to mixed material (barium tartaric acid and titanic acid) being 40:1, and ball milling is carried out at room temperature for 12 hours to obtain a mixed slurry; the obtained mixed slurry is washed, filtered, dried and ground to obtain a precursor powder; the obtained precursor powder is calcined at a high temperature of 750°C in a box furnace for 8 hours, and after grinding, barium titanate nanopowder is obtained.

[0036] Example 2

[0037] Preparation of barium titanate nanopowder:

[0038] Weigh barium tartrate and metatitanic acid according to the molar ratio of barium tartrate to metatitanic acid being 1.15:1, put them into a ball milling tank for mixing to obtain a mixed material, add water and stir well. Add 1.5 wt% lauroyl glutamate and 0.5 wt% fatty alcohol polyoxyethylene ether to the obtained mixed material liquid, and add 0.2 wt% sodium hydroxide and 0.2 wt% potassium hydroxide to adjust the pH value of the mixed material liquid to 4.9. Then add zirconia spheres according to the mass ratio of the ball milling medium to the mixed material (barium tartrate and metatitanic acid) being 30:1, and ball mill at room temperature for 8 h to obtain a mixed slurry; wash, filter by suction, dry and grind the obtained mixed slurry to obtain a precursor powder; calcine the obtained precursor powder in a box furnace at 950 °C for 4 h, and after grinding, obtain barium titanate nano powder.

[0039] Example 3

[0040] Preparation of barium titanate nano powder:

[0041] Weigh barium tartrate and metatitanic acid according to the molar ratio of barium tartrate to metatitanic acid being 1.25:1, put them into a ball milling tank for mixing to obtain a mixed material, add water and stir well. Add 1.5 wt% lauroyl glutamate and 0.15 wt% alcohol ether phosphate to the obtained mixed material liquid, and add 0.1 wt% ammonia water and 0.2 wt% potassium hydroxide to adjust the pH value of the mixed material liquid to 6.5. Then add zirconia spheres according to the mass ratio of the ball milling medium to the mixed material (barium tartrate and metatitanic acid) being 20:1, and ball mill at room temperature for 2 h to obtain a mixed slurry; wash, filter by suction, dry and grind the obtained mixed slurry to obtain a precursor powder; calcine the obtained precursor powder in a box furnace at 850 °C for 6 h, and after grinding, obtain barium titanate nano powder.

[0042] Example 4

[0043] Preparation of barium titanate nano powder:

[0044] Weigh barium tartrate and metatitanic acid according to the molar ratio of barium tartrate to metatitanic acid being 1.5:1, put them into a ball milling tank for mixing to obtain a mixed material, add water and stir well. Add 0.5 wt% lauroyl glutamate, 0.25 wt% alcohol ether phosphate and 0.15 wt% fatty alcohol polyoxyethylene ether to the obtained mixed material liquid, and add 0.1 wt% ethylenediamine, 0.1 wt% ammonia water and 0.3 wt% sodium hydroxide to adjust the pH value of the mixed material liquid to 7.5. Then add zirconia spheres according to the mass ratio of the ball milling medium to the mixed material (barium tartrate and metatitanic acid) being 50:1, and ball mill at room temperature for 24 h to obtain a mixed slurry; wash, filter by suction, dry and grind the obtained mixed slurry to obtain a precursor powder; calcine the obtained precursor powder in a box furnace at 1100 °C for 2 h, and after grinding, obtain barium titanate nano powder.

[0045] Example 5

[0046] Preparation of barium titanate nanometer powder:

[0047] Weigh barium tartrate and metatitanic acid according to the molar ratio of barium tartrate to metatitanic acid being 1.2:1, put them into a ball milling tank for mixing to obtain a mixed material, add water and stir well. Add 1.5 wt% fatty alcohol polyoxyethylene ether to the obtained mixed material liquid, and add 0.3 wt% ammonia water to adjust the pH value of the mixed material liquid to 4.5. Then add zirconia spheres according to the mass ratio of the ball milling medium to the mixed material (barium tartrate and metatitanic acid) being 25:1, and ball mill at room temperature for 5 h to obtain a mixed slurry; wash, filter by suction, dry and grind the obtained mixed slurry to obtain a precursor powder; calcine the obtained precursor powder at 600 °C in a box furnace for 10 h, and after grinding, obtain barium titanate nanometer powder.

[0048] Example 6

[0049] Preparation of barium titanate nanometer powder:

[0050] Weigh barium tartrate and metatitanic acid according to the molar ratio of barium tartrate to metatitanic acid being 1.4:1, put them into a ball milling tank for mixing to obtain a mixed material, add water and stir well. Add 2.1 wt% cetyltrimethylammonium bromide to the obtained mixed material liquid, and add 0.4 wt% sodium hydroxide to adjust the pH value of the mixed material liquid to 5.2. Then add zirconia spheres according to the mass ratio of the ball milling medium to the mixed material (barium tartrate and metatitanic acid) being 45:1, and ball mill at room temperature for 18 h to obtain a mixed slurry; wash, filter by suction, dry and grind the obtained mixed slurry to obtain a precursor powder; calcine the obtained precursor powder at 900 °C in a box furnace for 3 h, and after grinding, obtain barium titanate nanometer powder.

[0051] Material characterization and analysis

[0052] (I) XRD analysis

[0053] Use an X-ray powder diffractometer (XRD) to characterize and analyze the barium titanate nanometer powder prepared in Examples 1-6 respectively. The crystal structure of the barium titanate nanometer powder can be obtained through XRD, and the characterization results are as Figure 1 shown.

[0054] From Figure 1It can be seen that the barium titanate nanometer powder prepared in Example 1 is tetragonal barium titanate (completely matching with the standard phase card: tetragonal barium titanate PDF05-0626). At the same time, from the unit cell parameters, the c / a values of the barium titanate nanometer powder obtained in Examples 1-6 are 1.0081, 1.010, 1.0092, 1.011, 1.0095, and 1.0098 respectively, indicating that the content of the tetragonal phase in the obtained barium titanate nanometer powder product is relatively high.

[0055] (II) SEM analysis

[0056] The barium titanate nanometer powder prepared in Examples 1-6 was characterized by scanning electron microscopy (SEM), and the characterization results are shown as Figures 2 - 7 follows.

[0057] It can be seen from Figures 2 - 7 that the average particle sizes of the barium titanate nanometer powder obtained in Examples 1-6 are 50nm, 150nm, 120nm, 200nm, 130nm, and 100nm respectively; at the same time, it can be found that the dispersion of the powder is good.

[0058] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of barium titanate nano powder, characterized in that, It includes the following steps: (1) Mix barium tartrate and metatitanic acid to obtain a mixed material, add water and stir well. Add a dispersant to the obtained mixed material liquid, and add an alkali solution to adjust the pH value of the mixed material liquid. After ball milling treatment, a mixed slurry is obtained; The molar ratio of barium tartrate to metatitanic acid is 1-1.5:1; the dispersant is one or a combination of more of alcohol ether phosphate, lauroyl glutamate, fatty alcohol polyoxyethylene ether, cetyltrimethylammonium bromide; the dosage of the dispersant is 0.15-3 wt%; the pH value of the mixed material liquid is 3.8-6.5; (2) Wash, filter, dry and grind the obtained mixed slurry in sequence to obtain a precursor powder; (3) Calcinate the obtained precursor powder at a high temperature, and after grinding, barium titanate nano powder is obtained.

2. The preparation method of barium titanate nanopowder according to claim 1, characterized in that, In step (1), the alkali solution is one or a combination of more of ammonia water, ethylenediamine, sodium hydroxide, potassium hydroxide.

3. The preparation method of barium titanate nanometer powder according to claim 1, characterized in that, In step (1), the dosage of the alkali solution is 0.1-0.5 wt%.

4. The preparation method of barium titanate nanopowder according to claim 1, characterized in that, In step (1), the mass ratio of the ball milling medium used in the ball milling treatment to the mixed material is 20-50:1, and the ball milling time is 0.5-24 h.

5. The preparation method of barium titanate nano powder according to claim 1, characterized in that, In step (3), the temperature of the high-temperature calcination is 600-1100 °C, and the time is 0.5-12 h.

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