CN101311377A - Method for preparing barium titanate nanometer powder under room temperature - Google Patents

Abstract

The method for preparing barium titanate nanopowder at room temperature disclosed by the present invention includes preparing titanium oxyhydroxide precipitation and deionized aqueous solution of barium acetate as reaction materials, using ethylenediamine or a mixed solution of ethylenediamine and ethanolamine as a solvent, Potassium hydroxide of appropriate concentration is added to promote crystallization, and magnetic stirring is performed at room temperature for a certain period of time to obtain barium titanate nanopowder with good dispersibility. The invention does not need a high-temperature treatment process, is energy-saving and environment-friendly, and has a simple process, is easy to control, has low cost, and is easy to scale production. The prepared product has high purity, good dispersion and narrow particle size distribution, and the particle size can be adjusted by changing process parameters. The product has broad application prospects in the fields of microelectronic devices, electro-optic devices, storage materials, high-dielectric materials, and gas-sensitive materials.

Description

A method for preparing barium titanate nanopowder at room temperature

technical field

The invention relates to a method for preparing barium titanate nano powder at room temperature, belonging to the field of inorganic non-metallic materials.

Background technique

Due to the existence of the quantum size effect, nanomaterials have better physical and chemical properties than bulk materials, which also makes the preparation of nanomaterials a focus of attention and research in materials science in recent years. For ceramics, under the same process conditions, if well-dispersed and nearly spherical nanoparticles are used as the initial powder, a device with more dense sintering, better performance, and higher product consistency can be obtained.

Barium titanate is an important electronic ceramic material. Due to its high dielectric constant, low dielectric loss, pyroelectricity and ferroelectricity, it has been widely used in the production of multilayer ceramic chip capacitors (MLCC) and heat sensitive Resistor (PTCR), and also has very broad application prospects in electro-optic devices, infrared detectors and non-volatile ferroelectric memories. At present, under the general trend of miniaturization of electronic devices, in order to ensure the performance and reliability of devices, it is necessary to further reduce the particle size of barium titanate powder. Especially for MLCC (Multilayer Ceramic Chip Capacitor), in order to ensure high capacity and volumetric efficiency while miniaturizing the device, it is necessary to prepare barium titanate powder with smaller particle size and more uniformity. In addition, barium titanate powder with small particle size, narrow distribution range and good dispersibility has good sintering performance, and denser ceramic materials can be obtained at lower temperatures.

The traditional preparation method of barium titanate powder is solid-phase sintering method. Although this method is simple in process, it needs to react at above 1200°C to obtain barium titanate powder with good crystallinity and perovskite structure, which consumes a lot of energy and Higher equipment requirements. In addition, the powder prepared by the solid-state sintering method has low purity, serious particle agglomeration, easy growth, and difficult size control. In order to overcome these shortcomings, some wet chemical methods (including sol-gel method, microemulsion method, co-precipitation method (oxalate) method) are increasingly used to prepare barium titanate powder, but these methods also Both require a calcination process above 700°C to obtain barium titanate powder with good crystallinity. Although the calcination temperature is lower than that of the solid-phase sintering method, the high-temperature treatment process will inevitably cause particle coarsening and agglomeration, which is not conducive to the subsequent Ceramic sintering process. The hydrothermal method can prepare barium titanate powder with better crystallinity and dispersibility at a lower temperature (about 200° C.), and its particle size ranges from 0.05 to 0.4 microns. However, it is difficult to further reduce the particle size by hydrothermal method. Moreover, the equipment used in the hydrothermal method is a closed high-pressure reactor, which has the risk of explosion in addition to high cost. If barium titanate nanopowder can be synthesized at a lower temperature or even at room temperature, the production cost will be greatly reduced and the process will be simplified.

Contents of the invention

The object of the present invention is to provide a method for preparing barium titanate nanopowder at room temperature in order to overcome the problems in the prior art.

The preparation method of the barium titanate nanopowder of the present invention adopts a direct synthesis method at room temperature, and the specific steps are as follows:

1) Dissolving tetrabutyl titanate in absolute ethanol, adjusting the concentration of Ti ⁴⁺ ions in the solution to 0.1-1.0 mol/L;

2) Under stirring, add 1 to 3 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain a precipitate of titanium oxyhydroxide;

3) Dissolving barium acetate in deionized water to form an aqueous solution of barium acetate, adjusting the concentration of Ba ²⁺ ions in the solution to be 0.5 to 5.0 mol/L;

4) Potassium hydroxide is dissolved in deionized water, and an aqueous potassium hydroxide solution with a concentration of 10 to 30 mol/L is prepared;

5) Add titanium oxyhydroxide precipitation, barium acetate aqueous solution and potassium hydroxide aqueous solution to the organic amine solvent, and stir for at least 10 minutes to obtain a precursor slurry, wherein the molar volume fraction of titanium oxyhydroxide is 0.1-0.2 mol/L, the molar ratio of barium to titanium is 1.0-1.1, the molar volume fraction of potassium hydroxide is 0.5-1.0mol/L, and the volume base of the molar volume fraction is the total volume of the precursor slurry;

6) Continue stirring the prepared precursor slurry at room temperature for 12-72 hours, then let the obtained product settle naturally, then repeatedly wash with dilute acid and deionized water, filter, and dry to obtain barium titanate nanopowder.

In the preparation process of the present invention, the organic amine solvent used is ethylenediamine or a mixed solution of ethylenediamine and ethanolamine, wherein the volume of ethanolamine does not exceed 80% of the total volume of the mixed solution of ethylenediamine and ethanolamine.

In the preparation process of the present invention, the dilute acid used in step 6) is dilute acetic acid with a volume fraction less than 1%.

In the preparation process of the present invention, the purity of said tetrabutyl titanate, barium acetate, potassium hydroxide, absolute ethanol, ethylenediamine and ethanolamine is not lower than chemical purity.

The beneficial effects of the present invention are:

The invention uses organic amine as a solvent to directly prepare barium titanate nano powder with high purity, good crystallinity, good dispersibility and narrow particle size distribution at room temperature and atmospheric atmosphere, and the particle size can be adjusted by changing process parameters. Since the reaction medium is an organic solvent, the problem of agglomeration of primary particles during the crystal growth process is effectively solved. The direct synthesis method at room temperature of the present invention does not require expensive equipment, does not have a high-temperature treatment process, has low energy consumption, is easy to control process conditions, is low in cost, and is easy for industrialized production. The barium titanate nano powder prepared by the invention has broad application prospects in the fields of microelectronic devices, electro-optic devices, storage materials, high dielectric materials, gas sensitive materials and the like.

Description of drawings

Fig. 1 is the X-ray diffraction (XRD) collection of illustrative plates of the barium titanate nanopowder prepared by the present invention;

Fig. 2 is a transmission electron microscope (TEM) photo of the barium titanate nanopowder prepared in the present invention.

Detailed ways

Below in conjunction with embodiment further illustrate the present invention.

Example 1

1) Weigh 1.702g of tetrabutyl titanate, dissolve it in 10ml of absolute ethanol, and stir magnetically until dissolved;

2) Under stirring, add 1 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain titanium oxyhydroxide precipitate;

3) Weigh 1.277g of barium acetate, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

4) Weigh 2.736g of potassium hydroxide, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

5) Measure 15ml of ethylenediamine and 15ml of ethanolamine respectively, add them to the Erlenmeyer flask, and add the titanium precipitate prepared in step 2) and the solution prepared in step 3) and step 4) into the above-mentioned Erlenmeyer flask, and magnetically Stir for 24 hours;

6) Stop stirring, allow the product to precipitate naturally, pour out the upper layer solution to obtain a white precipitate, wash the precipitate 3 times with dilute acetic acid with a volume concentration of 0.5%, then wash 3 times with deionized water, and then place the product at 90 Dry in an oven at ℃ for 24 hours to obtain barium titanate nanopowder with good dispersibility. Its X-ray diffraction (XRD) spectrum is shown in Figure 1, and its transmission electron microscope (TEM) picture is shown in Figure 2.

Example 2

1) Weigh 0.340g of tetrabutyl titanate, dissolve in 10ml of absolute ethanol, and magnetically stir until dissolved;

2) In a stirring state, add 1 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain a precipitate of titanium oxyhydroxide;

3) Weigh 0.281g of barium acetate, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

4) Weigh 1.368g of potassium hydroxide, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

5) Measure 15ml of ethylenediamine and 15ml of ethanolamine respectively, add them to the Erlenmeyer flask, and add the titanium precipitate prepared in step 2) and the solution prepared in step 3) and step 4) into the above-mentioned Erlenmeyer flask, and magnetically Stir for 72h;

6) Stop stirring, allow the product to precipitate naturally, pour out the upper layer solution to obtain a white precipitate, wash the precipitate 3 times with dilute acetic acid with a volume concentration of 0.5%, then wash 3 times with deionized water, and then place the product at 90 Dry in an oven at ℃ for 24 hours to obtain barium titanate nanopowder with good dispersibility.

Example 3

1) Weigh 3.404g of tetrabutyl titanate, dissolve in 10ml of absolute ethanol, stir until dissolved by magnetic force;

2) In a stirring state, add 1 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain a precipitate of titanium oxyhydroxide;

3) Weigh 2.554g of barium acetate, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

4) Weigh 4.104g of potassium hydroxide, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

5) Measure 15ml of ethylenediamine and 15ml of ethanolamine respectively, add them to the Erlenmeyer flask, and add the titanium precipitate prepared in step 2) and the solution prepared in step 3) and step 4) into the above-mentioned Erlenmeyer flask, and magnetically Stir for 12h;

6) Stop stirring, allow the product to precipitate naturally, pour out the upper layer solution to obtain a white precipitate, wash the precipitate 3 times with dilute acetic acid with a volume concentration of 0.5%, then wash 3 times with deionized water, and then place the product at 90 Dry in an oven at ℃ for 24 hours to obtain barium titanate nanopowder with good dispersibility.

Example 4

1) Weigh 1.702g of tetrabutyl titanate, dissolve it in 10ml of absolute ethanol, and stir magnetically until dissolved;

2) In a stirring state, add 1 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain a precipitate of titanium oxyhydroxide;

3) Weigh 1.277g of barium acetate, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

4) Weigh 2.736g of potassium hydroxide, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

5) Measure 15ml of ethylenediamine, add it into the Erlenmeyer flask, and add the titanium precipitate prepared in step 2) and the solution prepared in step 3) and step 4) into the above-mentioned Erlenmeyer flask, and magnetically stir for 24 hours at room temperature;

6) Stop stirring, allow the product to precipitate naturally, pour out the upper layer solution to obtain a white precipitate, wash the precipitate 3 times with dilute acetic acid with a volume concentration of 0.5%, then wash 3 times with deionized water, and then place the product at 90 Dry in an oven at ℃ for 24 hours to obtain barium titanate nanopowder with good dispersibility.

Example 5

1) Weigh 1.702g of tetrabutyl titanate, dissolve it in 10ml of absolute ethanol, and stir magnetically until dissolved;

2) In a stirring state, add 1 ml of ammonia solution with a mass concentration of 30% to the ethanol solution of tetrabutyl titanate prepared in step 1), precipitate, filter, and wash to obtain a precipitate of titanium oxyhydroxide;

3) Weigh 1.277g of barium acetate, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

4) Weigh 2.736g of potassium hydroxide, dissolve in 2ml of deionized water, and magnetically stir until dissolved;

5) Measure 25ml of ethylenediamine and 5ml of ethanolamine respectively, add them to the Erlenmeyer flask, and add the titanium precipitate prepared in step 2) and the solution prepared in step 3) and step 4) into the above-mentioned Erlenmeyer flask. Stir for 24h;

6) Stop stirring, allow the product to precipitate naturally, pour out the upper layer solution to obtain a white precipitate, wash the precipitate 3 times with dilute acetic acid with a volume concentration of 0.5%, then wash 3 times with deionized water, and then place the product at 90 Dry in an oven at ℃ for 24 hours to obtain barium titanate nanopowder with good dispersibility.

Claims (4)

1. the method for a preparing barium titanate nanometer powder under room temperature is characterized in that may further comprise the steps:

1) tetrabutyl titanate is dissolved in dehydrated alcohol, the Ti in the regulator solution ⁴⁺Ionic concn is 0.1～1.0mol/L;

2) under the whipped state, add the ammonia soln of the mass concentration 30% of 1～3ml in the ethanolic soln of the tetrabutyl titanate that step 1) prepares, precipitation is filtered, washing, and the oxyhydroxide that obtains titanium precipitates;

3) barium acetate is dissolved in deionized water, forms the barium acetate aqueous solution, Ba in the regulator solution ²⁺Ionic concentration is 0.5～5.0mol/L;

4) potassium hydroxide is dissolved in deionized water, configuration concentration is the potassium hydroxide aqueous solution of 10～30mol/L;

5) oxyhydroxide precipitation, the barium acetate aqueous solution and the potassium hydroxide aqueous solution with titanium joins in the organic amine solvent, stirred at least 10 minutes, obtain the precursor slurry, wherein the molecular volume mark of the oxyhydroxide of titanium is 0.1～0.2mol/L, the mol ratio of barium and titanium is 1.0～1.1, the molecular volume mark of potassium hydroxide is 0.5～1.0mol/L, and molecular volume fractional volume radix is the cumulative volume of precursor slurry;

6) the precursor slurry with preparation at room temperature continues to stir 12～72h, allows the products therefrom natural subsidence then, washes repeatedly with diluted acid and deionized water again, filters, and dries, and obtains Barium Titanate nano-powder.

2. the method for preparing barium titanate nanometer powder under room temperature according to claim 1, it is characterized in that said organic amine solvent is the mixing solutions of quadrol or quadrol and thanomin, wherein the volume of thanomin is no more than 80% of quadrol and thanomin mixing solutions cumulative volume.

3. the method for preparing barium titanate nanometer powder under room temperature according to claim 1 is characterized in that said diluted acid is a volume fraction less than 1% dilute acetic acid.

4. the method for preparing barium titanate nanometer powder under room temperature according to claim 1 is characterized in that the purity of said tetrabutyl titanate, barium acetate, potassium hydroxide, dehydrated alcohol, quadrol and thanomin all is not less than chemical pure.

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