CN101092244A - Method for preparing porous balls of strontium titanate - Google Patents

Abstract

The method for preparing strontium titanate porous balls disclosed by the invention comprises preparing titanium oxyhydroxide precipitation and strontium deionized aqueous solution as reaction materials, adding potassium hydroxide of appropriate concentration to promote crystallization, and adding polyvinyl alcohol of appropriate concentration The morphology is controlled by the surfactant, and monodispersed strontium titanate porous balls are obtained through hydrothermal reaction at 150-200°C. The invention has the advantages of simple technological process, easy control of pore diameter and specific surface area, no pollution, low cost and easy large-scale production. The obtained product has stable crystalline quality, good dispersibility of powder particles and large specific surface area. It has broad application prospects in the fields of microelectronic devices, catalysts, solar cells, sensors, and luminescent materials.

Description

A kind of preparation method of strontium titanate porous ball

technical field

The invention relates to a method for preparing strontium titanate porous balls, belonging to the field of inorganic non-metallic materials.

Background technique

Strontium titanate is a very important complex oxide of ABO ₃ -type perovskite. Due to its excellent dielectric properties, semiconductivity, temperature stability and high voltage resistance, strontium titanate has become an important material for the preparation of multifunctional electronic ceramics. important inorganic materials. At the same time, strontium titanate has the same band gap (3.2eV) as titanium dioxide. In recent years, it has attracted extensive research interest in the fields of photocatalysis, solar cell photoelectrodes, sensors, and luminescence. Due to its unique structure, porous materials are widely used in separation, catalysis and other fields. Porous strontium titanate has a large specific surface area, which is expected to improve the performance of related aspects.

The traditional method of preparing strontium titanate is the solid phase reaction method. Although the process is simple, the powder prepared by this method is low in purity, and because it requires a high temperature calcination process, it is easy to cause very serious agglomeration and it is difficult to control the particles. size and shape. Compared with this, the liquid-phase method shows great advantages in controlling the size and shape of the powder, especially the surfactant-assisted hydrothermal method, which is simple in operation, low in equipment requirements, and low in cost. used by researchers.

Contents of the invention

The object of the present invention is to provide a method for preparing strontium titanate porous balls with simple process, easy operation and low cost.

The preparation method of the strontium titanate porous ball of the present invention adopts a hydrothermal synthesis method, 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 0.5-1.0 mol/L;

2) Under stirring, add 2 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 strontium nitrate in deionized water to form an aqueous solution of strontium nitrate, adjusting the concentration of strontium ions in the solution to be 1.5 to 3.0 mol/L;

4) Potassium hydroxide and polyvinyl alcohol were dissolved in deionized water respectively, and a potassium hydroxide aqueous solution with a concentration of 2 to 5 mol/L and an aqueous polyvinyl alcohol solution with a concentration of 4 to 16 g/L were prepared;

5) Add titanium oxyhydroxide precipitation, strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol aqueous solution to the inner tank of the reactor, and use deionized water to adjust the volume of the reaction materials in the inner tank of the reactor to reach the inner tank of the reactor. 70% to 90% of the volume, stirred for at least 10 minutes, wherein the molar volume fraction of titanium oxyhydroxide is 0.1 to 0.2mol/L, the molar ratio of strontium to titanium is 3 to 6, and the molar volume fraction of potassium hydroxide is 0.5-1.5mol/L, the mass volume fraction of polyvinyl alcohol is 1-4g/L, and the volume base of the mole volume fraction is the volume of all materials introduced into the inner tank of the reactor;

6) Put the reactor liner equipped with the reaction materials in step 5) in the reactor, seal it, heat it at 150-200°C for 2-6 hours for hydrothermal treatment, then let the reactor cool down to room temperature naturally, after unloading the reactor , the reaction product was repeatedly washed with 0.5 wt% dilute nitric acid and deionized water, filtered and dried to obtain strontium titanate porous balls.

In the preparation process of the present invention, the reaction kettle used is a polytetrafluoroethylene liner and a closed reaction kettle with a stainless steel sleeve.

In the preparation process of the present invention, the purity of said tetrabutyl titanate, strontium nitrate, potassium hydroxide, polyvinyl alcohol and absolute ethanol is not lower than chemical purity.

The beneficial effects of the present invention are:

The invention adopts a simple polymer surfactant-assisted hydrothermal method to prepare strontium titanate porous balls with high purity, good crystal stability, monodispersity and large specific surface area, and the pore diameter and specific surface area can be adjusted by changing process parameters. The hydrothermal synthesis method of the invention has simple equipment, easy control of process conditions, low preparation cost and easy industrial production. The strontium titanate porous ball of the invention has broad application prospects in the fields of microelectronic devices, catalysts, solar cells, sensors, luminescent materials and the like.

Description of drawings

Fig. 1 is the XRD pattern of the strontium titanate porous ball synthesized by the present invention;

Fig. 2 is the scanning electron microscope (SEM) photograph of the strontium titanate porous sphere synthesized by the present invention;

Fig. 3 is the _N2 adsorption-desorption curve of the strontium titanate porous sphere synthesized by the present invention.

Detailed ways

Below in conjunction with embodiment further illustrate the present invention.

Example 1

1) Dissolving tetrabutyl titanate in absolute ethanol, adjusting the concentration of Ti ⁴⁺ ions in the solution to 0.5mol/L;

2) Under stirring, add 2ml of 30wt% ammonia solution to the ethanol solution of tetrabutyl titanate, precipitate, filter, and wash with deionized water for 6 times to obtain a precipitate of titanium oxyhydroxide;

3) dissolving strontium nitrate in deionized water, adjusting the ion concentration ^of Sr in the solution to be 1.5mol/L;

4) Potassium hydroxide and polyvinyl alcohol were dissolved in deionized water respectively to obtain a potassium hydroxide solution with a concentration of 2mol/L and a polyvinyl alcohol solution with a concentration of 16g/L;

5) Precipitate titanium oxyhydroxide, add strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol aqueous solution to the inner tank of the reactor, and use deionized water to adjust the reaction materials in the inner tank of the reactor to reach the inner tank of the reactor 90% of the gallbladder volume, stirred for 10 minutes, wherein the molar volume fraction of titanium oxyhydroxide is 0.1mol/L, the molar ratio of strontium to titanium is 3, the molar volume fraction of potassium hydroxide is 0.5mol/L, polyethylene The mass volume fraction of alcohol is 4g/L, and the volume basis of the molar volume fraction is the volume of all materials introduced in the reactor liner;

6) Place the reactor liner equipped with the reaction materials in the reactor, seal it, and heat it at 200°C for 6 hours to carry out hydrothermal treatment, then allow the reactor to cool down to room temperature naturally, after unloading the reactor, use 0.5wt% dilute The reaction product was repeatedly washed with nitric acid and deionized water for 6 times, filtered, and dried at 90°C to obtain monodisperse strontium titanate porous spheres with an average particle size of 200 nm. The specific surface area of the product is 89.2m ² /g, the pore volume is 0.27cm ³ /g, and the average pore diameter is 12.0nm. See Figure 1 for its XRD pattern, Figure 2 for its scanning electron microscope (SEM) photo, and Figure 3 for its N ₂ adsorption-desorption curve.

Example 2

1) Dissolving tetrabutyl titanate in absolute ethanol, adjusting the concentration of Ti ⁴⁺ ions in the solution to 0.5mol/L;

2) In the stirring state, add 2ml of 30wt% ammonia solution to the ethanol solution of tetrabutyl titanate, precipitate, filter, and wash with deionized water for 6 times to obtain the precipitate of titanium oxyhydroxide;

3) dissolving strontium nitrate in deionized water, adjusting the ion concentration ^of Sr in the solution to be 3.0mol/L;

4) Potassium hydroxide and polyvinyl alcohol were dissolved in deionized water respectively to obtain a potassium hydroxide solution with a concentration of 2mol/L and a polyvinyl alcohol solution with a concentration of 16g/L;

5) Precipitate titanium oxyhydroxide, add strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol aqueous solution to the inner tank of the reactor, and use deionized water to adjust the reaction materials in the inner tank of the reactor to reach the inner tank of the reactor 90% of the gallbladder volume, stirred for 10 minutes, wherein the molar volume fraction of titanium oxyhydroxide is 0.1mol/L, the molar ratio of strontium to titanium is 6, the molar volume fraction of potassium hydroxide is 0.5mol/L, polyethylene The mass volume fraction of alcohol is 4g/L, and the volume basis of the molar volume fraction is the volume of all materials introduced in the reactor liner;

6) Place the reactor liner equipped with the reaction materials in the reactor, seal it, and heat it at 200°C for 2 hours to carry out hydrothermal treatment, then let the reactor cool down to room temperature naturally, after unloading the reactor, use 0.5wt% dilute The reaction product was repeatedly washed with nitric acid and deionized water for 6 times, filtered, and dried at 90°C to obtain monodisperse strontium titanate porous spheres with an average particle size of 200 nm.

Example 3

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

2) Under stirring, add 3ml of 30wt% ammonia solution to the ethanol solution of tetrabutyl titanate, precipitate, filter, and wash with deionized water for 6 times to obtain titanium oxyhydroxide precipitate;

3) dissolving strontium nitrate in deionized water, adjusting the ion concentration ^of Sr in the solution to be 3.0mol/L;

4) Potassium hydroxide and polyvinyl alcohol were dissolved in deionized water respectively to obtain a potassium hydroxide solution with a concentration of 5 mol/L and a polyvinyl alcohol solution with a concentration of 4 g/L;

5) Precipitate titanium oxyhydroxide, add strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol aqueous solution to the inner tank of the reactor, and use deionized water to adjust the reaction materials in the inner tank of the reactor to reach the inner tank of the reactor 90% of the gallbladder volume, stirred for 10 minutes, wherein the molar volume fraction of titanium oxyhydroxide is 0.2mol/L, the molar ratio of strontium to titanium is 3, the molar volume fraction of potassium hydroxide is 1.5mol/L, polyethylene The mass volume fraction of alcohol is 1g/L, and the volume basis of the molar volume fraction is the volume of all materials introduced into the reactor liner;

6) Place the liner of the reaction kettle equipped with the reaction materials in the reaction kettle, seal it, and heat it at 150°C for 6 hours to carry out hydrothermal treatment, let the reaction kettle cool down to room temperature naturally, after unloading the kettle, use 0.5wt% dilute nitric acid The reaction product was repeatedly washed with deionized water for 6 times, filtered, and dried at 90° C. to obtain monodisperse strontium titanate porous spheres with an average particle size of 200 nm.

Example 4

1) Dissolving tetrabutyl titanate in absolute ethanol, adjusting the concentration of Ti ⁴⁺ ions in the solution to 0.8mol/L;

2) Under stirring, add 3ml of 30wt% ammonia solution to the ethanol solution of tetrabutyl titanate, precipitate, filter, and wash with deionized water for 6 times to obtain titanium oxyhydroxide precipitate;

3) dissolving strontium nitrate in deionized water, adjusting the ion concentration ^of Sr in the solution to be 2.4mol/L;

4) Potassium hydroxide and polyvinyl alcohol were dissolved in deionized water respectively to obtain a potassium hydroxide solution with a concentration of 2mol/L and a polyvinyl alcohol solution with a concentration of 10g/L;

5) Precipitate titanium oxyhydroxide, add strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol aqueous solution to the inner tank of the reactor, and use deionized water to adjust the reaction materials in the inner tank of the reactor to reach the inner tank of the reactor 70% of the gallbladder volume, stirred for 12 minutes, wherein the molar volume fraction of titanium oxyhydroxide is 0.2mol/L, the molar ratio of strontium to titanium is 3, the molar volume fraction of potassium hydroxide is 0.5mol/L, polyethylene The mass volume fraction of alcohol is 2.5g/L, and the volume basis of the molar volume fraction is the volume of all materials introduced in the reactor liner;

6) Place the liner of the reaction kettle equipped with the reaction materials in the reaction kettle, seal it, and heat it at 150°C for 6 hours to carry out hydrothermal treatment, let the reaction kettle cool down to room temperature naturally, after unloading the kettle, use 0.5wt% dilute nitric acid The reaction product was repeatedly washed with deionized water for 6 times, filtered, and dried at 90° C. to obtain monodisperse strontium titanate porous spheres with an average particle size of 150 nm.

Claims (3)

1. the preparation method of a porous balls of strontium titanate 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 0.5～1.0mol/L;

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

3) strontium nitrate is dissolved in deionized water, forms the strontium nitrate aqueous solution, the concentration of strontium ion is 1.5～3.0mol/L in the regulator solution;

4) potassium hydroxide and polyvinyl alcohol are dissolved in deionized water respectively, configuration concentration is that potassium hydroxide aqueous solution and the concentration of 2～5mol/L is the polyvinyl alcohol water solution of 4～16g/L;

5) oxyhydroxide with titanium precipitates, the strontium nitrate aqueous solution, potassium hydroxide aqueous solution and polyvinyl alcohol water solution join in the reactor inner bag, reach reactor inner bag volumetrical 70%～90% with the reaction mass volume in the deionized water conditioned reaction still inner bag, stirred at least 10 minutes, wherein the molecular volume mark of the oxyhydroxide of titanium is 0.1～0.2mol/L, the mol ratio of strontium and titanium is 3～6, the molecular volume mark of potassium hydroxide is 0.5～1.5mol/L, the quality volume fraction of polyvinyl alcohol is 1～4g/L, and molecular volume fractional volume radix is the volume of material in all introducing reactor inner bags;

6) the reactor inner bag that step 5) is disposed reaction mass places reactor, sealing, be incubated 2～6 hours down at 150～200 ℃ and carry out hydrothermal treatment consists, allow reactor naturally cool to room temperature then, after unloading still, with rare nitric acid and the deionized water repetitive scrubbing reaction product of 0.5wt%, filter, dry, obtain porous balls of strontium titanate.

2. the preparation method of porous balls of strontium titanate according to claim 1 is characterized in that reactor is a polytetrafluoroethylliner liner, stainless steel external member closed reaction kettle.

3. the preparation method of porous balls of strontium titanate according to claim 1 is characterized in that the purity of said tetrabutyl titanate, strontium nitrate, potassium hydroxide, polyvinyl alcohol and dehydrated alcohol all is not less than chemical pure.

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