JP2000281338A - Production of barium titanate powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of barium titanate powder by which uniform and fine barium titanate powder is produced inexpensively by reducing the residual content of free unreacted barium ion and effectively accelerating the formation reaction of barium titanate, and which method is capable of being applied to a liquid phase method and further preferably applied to a hydroxide-alkoxide method. SOLUTION: Barium hydroxide, water and titanium alkoxide are brought into contact with one another to hydrolyze the titanium alkoxide. Then, a water-soluble organic solvent is added to the obtained reaction solution so as to reduce the solubility of the residual barium iron dissolving as an unreacted substance in the reaction solution and to accelerate forming reaction of the barium titanate. The contact is preferably carried out by mixing an aqueous barium hydroxide solution and a titanium alkoxide. Further, the suitable water- soluble organic solvent is at least one kind selected from solvents having dielectric constants lower than that of water, preferably <=40, such as acetone, t-butyl alcohol and tetrahydrofuran.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing barium titanate, and more particularly to a method for producing barium titanate powder useful as a raw material for dielectric materials, piezoelectric materials, semiconductors, and various other electronic materials.

[0002]

BACKGROUND OF THE INVENTION Conventionally, barium titanate powder has been used as a raw material for dielectric materials, piezoelectric materials, semiconductors and other various electronic materials. As methods for producing such barium titanate, the following methods are known. That is, a solid phase reaction method in which a mixture of titanium oxide and barium carbonate is heated to a high temperature of 1300 ° C. or more and reacted in a solid phase (Industrial Chemistry Magazine, Vol. 70, pp. 847-853, (196
7)):: An oxalate method (J. Am. Ceram.) For obtaining a precipitate of BaTiO (C ₂ O ₄ ) ₂ by reaction in an aqueous solution of TiCl ₄ , BaCl ₂ and oxalic acid and thermally decomposing it. Soc., 48
Vol., Pages 644 to 647 (1965)): hydrothermal synthesis of a mixture of barium hydroxide and titanium hydroxide and calcining the obtained reaction product (Industrial Chemistry Magazine, Vol. 59, 891) Pp. 894 (1956)) (Journal of the Chemical Society of Japan, pp. 985-990 (1975)): preparing a mixed alkoxide solution of barium alkoxide and titanium alkoxide, hydrolyzing these alkoxides, and obtaining the obtained hydrolysis. Alkoxide method of calcining the product (J. Am. Ceram. Soc., Vol. 52, pp. 523-526)
(1969)), (J. Am. Ceram. Soc., 54, 548-
553 (1971)): hydroxide-alkoxide method of calcining a reaction product obtained by hydrolysis of titanium alkoxide in an aqueous barium hydroxide solution (J. Am. Ceram. Soc., Vol. 49, 29)
Pages 1 to 295 (1966)) are known.

In recent years, as electronic components have become smaller, lighter, and larger in capacity, for example, capacitors using barium titanate powder have also been required to have higher capacities, such as multilayer ceramic capacitors. A capacitor with an increased capacity by stacking has been proposed. In such a multilayer capacitor, it is required that the thickness of one layer constituting the multilayer capacitor be thin and uniform, and it is desired that the barium titanate powder used is uniform fine particles. .

[0004] However, in the solid-phase reaction method and the oxalate method, calcination at a high temperature is necessary, and agglomeration or grain growth is generated by the calcination, so that a fine powder cannot be obtained. . On the other hand, according to the liquid phase method such as the hydrothermal synthesis method, the alkoxide method, and the hydroxide-alkoxide method, barium titanate fine powder can be obtained industrially.

However, the above hydrothermal synthesis method, hydroxide
-Hydroxylation used as a raw material in the alkoxide method
During the hydrolysis reaction of barium and alkoxide method
The resulting barium hydroxide has a high solubility in water and
Barium titanate formation reaction hardly proceeds completely. Ma
Barium ion (Ba) that is free in the reaction solution ²⁺
Ion) is filtered, centrifuged or decanted
When solid-liquid separation is performed by operation,
And the Ba / Ti ratio of the resulting precipitate is set to a stoichiometric ratio of 1.
Strictly difficult to control.

Therefore, as means for strictly controlling the Ba / Ti ratio, for example, (a): a method in which an alkali metal hydroxide such as KOH is added to a reaction solution to make the pH 11-11 strong alkalinity. (J. Am. Chem. Soc., 77, 619
(P. 4 (1955), JP-A-4-12020, etc.), (b): Ba / Ti (molar ratio) in the charged raw material is increased by about 10 mol% from the beginning, and unreacted components in the reactants For removing residual barium ions by washing
286923) has been proposed.

[0007] However, there is a problem that much effort is required to wash and remove the alkali metal ions and the excessive amount of barium ions used for pH adjustment.
Another method of controlling and immobilizing free barium ions is to add an insolubilizing agent such as ammonium carbonate to the reaction solution (Japanese Patent Publication No. 4-154617). In this method, barium ions are fixed as barium carbonate and the outflow thereof is suppressed. However, barium carbonate is not decomposed unless the temperature is high, and therefore, there is a problem that the barium titanate formation reaction also becomes high in temperature.

According to the method of synthesizing barium titanate using a hydrothermal reaction described in Japanese Patent Publication No. 59259/1992, the BaTiO ₃ generation reaction can be advanced. Similarly to the above, the hydrothermal reaction is carried out at a temperature of 100 ° C. or more under pressure, so that a special pressure reaction vessel (autoclave) is required, and there is a problem that the equipment cost is increased industrially.

When a barium hydroxide aqueous solution and titanium alkoxide are mixed and hydrolyzed, unreacted Ba ions of about 10 mol% with respect to the charged amount usually remain in the obtained reaction solution and are dissolved. There is a problem. After extensive research to solve such problems, the solubility of barium ions in the solution was reduced by adding a water-soluble organic solvent having a relatively low dielectric constant compared to water to the reaction solution. As a result, it was found that the barium titanate generation reaction progressed, and almost no unreacted barium ions remained in the reaction solution, and the present invention was completed.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art as described above, and to reduce the remaining amount of free unreacted barium ions and promote the barium titanate production reaction. It is an object of the present invention to provide a method for producing barium titanate fine powder capable of producing a uniform and fine barium titanate powder at low cost.

In particular, the present invention can be applied to a liquid phase method, more preferably to a hydroxide-alkoxide method, and can be applied to a liquid phase method represented by the hydroxide-alkoxide method. A method for producing a barium titanate fine powder capable of reducing the residual amount of free unreacted barium ions, efficiently promoting a barium titanate generation reaction, and producing a uniform and fine barium titanate powder at a low cost. It is intended to provide.

[0012]

SUMMARY OF THE INVENTION The process for producing barium titanate powder according to the present invention comprises contacting barium hydroxide with water and a titanium alkoxide to hydrolyze the titanium alkoxide, and then adding a water-soluble organic solvent to the obtained reaction solution. In addition, the present invention is characterized in that the solubility of barium ions remaining and dissolved as unreacted substances in the reaction solution is reduced, and the barium titanate generation reaction is promoted.

In the present invention, it is desirable that the above-mentioned contact between barium hydroxide, water and titanium alkoxide is performed by mixing an aqueous barium hydroxide solution and titanium alkoxide. In the present invention, the water-soluble organic solvent,
Preferably, the dielectric constant is lower than the dielectric constant of water,
Further, the dielectric constant of the water-soluble organic solvent is preferably 40 or less, and in particular, the water-soluble organic solvent is at least one selected from acetone, t-butyl alcohol, and tetrahydrofuran. Is desirable.

In the present invention, the titanium alkoxide is desirably used after being dissolved in an organic solvent. The method for producing barium titanate powder according to the present invention is particularly effective when applied to a liquid phase method, and is further suitably applicable to a hydroxide-alkoxide method, and is applicable to the hydroxide-alkoxide method. Thereby, the remaining amount of free unreacted barium ions can be reduced, the barium titanate generation reaction can be efficiently promoted, and uniform and fine barium titanate powder can be produced at low cost.

The barium titanate powder thus obtained is uniform and fine, and has excellent characteristics for use in multilayer ceramic capacitors.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for producing barium titanate powder according to the present invention will be specifically described. In the present invention, the titanium alkoxide is hydrolyzed by contacting barium hydroxide with water and a titanium alkoxide, and then a water-soluble organic solvent is added to the obtained reaction solution, which remains as an unreacted substance in the reaction solution. It reduces the solubility of dissolved barium ions and promotes the barium titanate production reaction. To bring barium hydroxide, water and titanium alkoxide into contact with each other as described above, for example, (a): a method in which these are added to a reactor at once and stirring is performed, and (b): a method in which barium hydroxide and the like are added A method in which an aqueous barium hydroxide solution prepared by previously mixing water and a titanium alkoxide solution, preferably a titanium alkoxide solution previously dissolved in an organic solvent, is added to a reactor and mixed. In the present invention, the latter (b) is preferred.

The barium hydroxide used in this case, particularly the barium hydroxide aqueous solution and the titanium alkoxide, will be described first. <Barium hydroxide (barium hydroxide aqueous solution)> The production method of the barium hydroxide aqueous solution is not particularly limited.
As a method for producing the barium hydroxide aqueous solution, for example, Ba
(OH) ₂ · 8H ₂ O barium hydroxide hydrates such as, or barium hydroxide anhydride, or a method of obtaining the aqueous solution of the barium oxide is dissolved in water. Further, a method of obtaining an aqueous barium hydroxide solution by hydrolyzing barium alkoxide, adding an alkali such as caustic soda (NaOH) to a water-soluble barium salt such as BaCl ₂ or Ba (NO ₃ ) ₂ and removing impurities, Ba (OH) ₂ .nH ₂ O thus obtained may be dissolved in water to obtain a barium hydroxide aqueous solution.

It is desirable that the concentration of the aqueous barium hydroxide solution used for the hydrolysis of the titanium alkoxide be lower than the solubility at that temperature. Incidentally, the solubility of barium hydroxide per 100 g of water is 1.67 g at 0 ° C., 4.29 g at 25 ° C., and 10% at 80 ° C.
1.4 g, and low solubility near room temperature. In the present invention, from the practical viewpoint and the economic viewpoint of this method for producing barium titanate powder, 40 barium hydroxide having a high solubility of barium hydroxide is used.
Barium concentration of 0.1 to 3 mol / kg while heating at ~ 90 ° C
It is preferable to use an aqueous barium hydroxide solution to an extent.

In the present invention, usually, the above-mentioned aqueous barium hydroxide solution and the following titanium alkoxide (preferably an organic solvent solution of titanium alkoxide) are mixed, but solid barium hydroxide, water and titanium are mixed. An alkoxide (preferably, a solution of titanium alkoxide in an organic solvent) may be contacted by a method such as mixing or the like to perform a barium titanate generation reaction. <Titanium alkoxide> The titanium alkoxide is preferably represented by the formula [I]: [Ti (OR) ₄ , R: an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms].

Such a titanium alkoxide is, for example,
Dissolved in alcohol [ROH, R: alkyl group as above]
Blow-in ammonia gas into titanium tetrachloride
NH _FourObtained by a conventionally known method for removing Cl
be able to. The type of titanium alkoxide is particularly limited.
Anything is not specified, but you can use
In consideration of utility, R in the above formula [I] has 1 to 6 carbon atoms.
And a linear or branched alkyl group having the formula:

The alkyl group (R) includes, for example,
Examples include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a normal pentyl group, a normal hexyl group, and the like, but are not limited thereto. In the present invention, an aqueous solution of barium hydroxide and a titanium alkoxide are mixed, and when the titanium alkoxide is hydrolyzed, when the titanium alkoxide used is a solid or the like, the titanium alkoxide is dissolved in an organic solvent and used. Is preferred.

The organic solvent is not particularly limited as long as it can dissolve the titanium alkoxide. Examples thereof include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and normal butyl alcohol; and aliphatic hydrocarbons such as hexane, heptane and octane. Hydrogens include aromatic hydrocarbons such as benzene, toluene, and xylene. These organic solvents can be used alone or in combination of two or more.

In the present invention, for example, when the above-mentioned hydrolysis reaction is carried out at room temperature, when the titanium alkoxide used is titanium isopropoxide, titanium normal butoxide or the like which is liquid at room temperature, the titanium alkoxide and water The reaction with barium oxide can be performed in the absence of an organic solvent. However, considering the reaction operability, it is preferable to use titanium alkoxide by dissolving it in the above-described organic solvent.

The titanium alkoxide concentration of the organic solvent solution of titanium alkoxide is preferably 0.1 to 3 mol / kg, and considering practicality and economy, it is preferably 0.5 to 2 mol / kg.
More preferably, it is mol / kg. In the present invention,
The above-described barium hydroxide aqueous solution and the titanium alkoxide, preferably the organic solvent solution of the titanium alkoxide, may be used in an amount that theoretically satisfies Ba / Ti (molar ratio) = 1. Titanium alkoxide or an organic solvent solution thereof and barium hydroxide or an aqueous solution thereof are 1.00 in terms of Ba / Ti (molar ratio) in consideration of the amount of leakage of barium ions during solid-liquid separation.
To 1.05, preferably 1.00 to 1.02, more preferably 1.00 to 1.01.

When the above-mentioned aqueous barium hydroxide solution is mixed with a titanium alkoxide (preferably, a titanium alkoxide dissolved in an organic solvent) to hydrolyze the titanium alkoxide, the reaction mechanism has not been fully elucidated. The resulting reaction solution contains Ti (OH) _x (OR) _4-x (x = 1 to 4) generated by hydrolysis of titanium alkoxide.
And barium titanate (solid, crystalline) produced by the reaction of the hydrolyzate of titanium alkoxide and barium hydroxide, as well as a small amount of barium ions, etc. ing.

In the present invention, a water-soluble organic solvent is added to such a reaction solution to reduce the solubility of barium ions remaining and dissolved in the reaction solution as unreacted substances, thereby reducing the barium titanate formation reaction. Promoted. Hereinafter, the water-soluble organic solvent will be described in detail. <Water-soluble organic solvent> The water-soluble organic solvent can be used without any particular limitation as long as it can reduce the solubility of barium ions by being added to the obtained reaction solution. For example, when the above hydrolysis reaction is carried out at room temperature (20 ° C.), the dielectric constant of water is 80.4 (20 ° C.).
° C), a water-soluble organic solvent having a dielectric constant lower than 40 ° C, more preferably a dielectric constant of 40 or lower, particularly preferably 30 or lower, is added to the obtained reaction solution to obtain a slurry after hydrolysis. Can be reduced in the solubility of barium ions remaining and dissolved in the aqueous barium titanate solution (reaction liquid).

In the present invention, depending on the concentration of barium ions in the slurry-like aqueous barium titanate solution, a water-soluble organic solvent having a dielectric constant of 40 or less at room temperature is taken into consideration in view of industrial productivity and the like. 0.2 to 10 times the volume of water in the slurry (volume ratio), preferably 0.5 to
Add 5 times (volume ratio), and add Ba at the time of solid-liquid separation described later.
The amount of ion leakage is preferably 5 mol% or less, preferably 2 mol% or less, more preferably 1 mol% or less, based on the charged amount. If the leakage amount of Ba ions is larger than this, the Ba /
It becomes difficult to precisely control the Ti molar ratio to a value close to 1, and the production cost of the obtained barium titanate powder tends to increase.

Further, in the present invention, the charged Ba is taken into consideration in consideration of the amount of barium ion leakage during solid-liquid separation described later.
By adjusting the / Ti molar ratio, it is desirable to adjust the Ba / Ti molar ratio of the obtained barium titanate more strictly to a value close to 1. The water-soluble organic solvent used in the present invention has a solubility of the water-soluble organic solvent in water of preferably about 20% or more, more preferably 50% or more.
% Is preferable. At solubility below this,
The effect of lowering the solubility of Ba ions is reduced, and tends to be impractical.

The dielectric constant preferably used in the present invention is 40.
The following water-soluble organic solvents may be either protic or aprotic, and as the protic solvent,
For example, ethyl alcohol, isopropyl alcohol,
T-butyl alcohol and the like are mentioned, and among them, t-butyl alcohol having a low dielectric constant is preferably used. Examples of the aprotic solvent include acetonitrile, acetone, methyl ethyl ketone, tetrahydrofuran and the like, and among them, acetone and tetrahydrofuran having a low dielectric constant and a high solubility in water are preferably used. These water-soluble organic solvents can be used alone or in combination of two or more.

<Separation of barium titanate powder, calcination, etc.>
In the present invention, the aqueous solution of barium hydroxide and titanium alkoxide are mixed and hydrolyzed as described above, and the above-described water-soluble organic solvent having a dielectric constant of 40 or less is added to the reaction solution. It is preferably 20 ° C. or less, more preferably 10 ° C. or less, and the lower the temperature, the better. However, the lower limit is -10 in consideration of industrial properties.
A temperature range of at least 0 ° C, preferably at least 0 ° C, is employed.
In such a temperature range, it is usually desirable to cool for 1 to 6 hours, preferably 2 to 4 hours. During this time, in the present invention, it is desirable to stir the reaction solution.

In the present invention, after the reaction solution to which the water-soluble organic solvent has been added is cooled, the obtained slurry reaction solution (hydrolyzate) is filtered, centrifuged, decanted, etc., and solidified. By liquid separation, barium titanate can be taken out as a precipitate. The obtained precipitate is dried by a general drying method such as ventilation drying, vacuum drying and freeze drying. The drying temperature of the precipitate, to prevent its aggregation,
It is preferable that the temperature be as low as possible.
The range of 0-140 degreeC is desirable.

The obtained dry powder can be used as it is as barium titanate powder.
It is preferable to perform calcination at a temperature in the range of from 1000C to 1000C. The barium titanate powder thus obtained is
Uniform and fine composition (average particle size: 0.05-0.5μ)
m, measurement method; observation with an electron microscope) and has excellent characteristics for use in multilayer ceramic capacitors.

[0033]

As is clear from the above description, according to the present invention, a reaction solution obtained by mixing a barium hydroxide aqueous solution and a titanium alkoxide and hydrolyzing the aqueous solution has a relatively lower dielectric constant than water. By adding a neutral organic solvent to lower the solubility of Ba ions remaining and dissolved in the reaction solution, the barium titanate generation reaction can be advanced. As a result, unreacted Ba ions hardly remain in the reaction solution, and barium titanate powder can be obtained by performing simple solid-liquid separation such as filtration without adding a special operation. There is also an excellent effect that the manufacturing cost is greatly reduced. Also,
In the present invention, the organic solvent used can be recovered and reused.

[0034]

EXAMPLES Hereinafter, the method for producing barium titanate powder according to the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0035]

Example 1 1 g of deionized water degassed with 117 g of CO ₂
5.78 g (0.05 mol) of Ba (OH) ₂ .8H ₂ O
Was added and heated to 80 ° C. to dissolve. This solution was cooled to 60 ° C. in a stream of N ₂ gas, and stirred at a concentration of 1 mol / kg of titanium tetra n-butoxide [Ti (On-C).
₄ H _{9) 4]} in toluene solution 49.5 g [16.8 g as titanium tetra-n- butoxide (0.0495 mol)
And a Ba / Ti molar ratio corresponding to 1.01] was added thereto, and stirring was continued for 1 hour under reflux conditions (temperature: about 85 ° C.).

Further, heating at a normal pressure (final temperature; up to 100 ° C.) was continued for about 1 hour to distill off toluene and n-butyl alcohol. After adjusting the amount of water in the obtained slurry to 100 ml, acetone (dielectric constant 21.
5) After adding 100 ml, the mixture was cooled to 10 ° C. and stirred for 2 hours. After stirring, this slurry was subjected to solid-liquid separation by filtration. The amount of Ba leaked into the filtrate was 1.0 mol
l%. The obtained solid content (precipitate) is
Blow dry for 2 hours and calcine at 850 ° C for 1 hour.
aTiO ₃ powder was obtained.

X-ray diffraction analysis of the powder showed that B
It was confirmed to be aTiO ₃ . An X-ray diffraction chart is shown in FIG. Further, the Ba / Ti molar ratio of the calcined powder is
The analysis values obtained by the glass bead method using fluorescent X-rays are as follows:
1.00.

The average particle size of the barium titanate powder measured by observation with an electron microscope was 0.2 μm, which was extremely fine and had a uniform composition.

[0039]

Example 2 117 g of ion-exchanged water from which CO ₂ was removed
5.78 g (0.05 mol) of Ba (OH) ₂ .8H ₂ O
Was added and heated to 80 ° C. to dissolve. This solution was cooled to 60 ° C. in a stream of N ₂ gas, and 1 mol / kg of titanium tetra-n-butoxide [Ti (On-C) was added while stirring.
₄ H _{9) 4]} in toluene solution 49.5 g [16.8 g as titanium tetra-n- butoxide (0.0495 mol)
And a molar ratio of Ba / Ti corresponding to 1.01] was added thereto, and stirring was continued for 1 hour under reflux. Further, heating at normal pressure (final temperature; up to 100 ° C.) was continued for about 1 hour, and toluene and n-butyl alcohol were distilled off. After adjusting the amount of water in the obtained slurry to 100 ml, 200 ml of t-butyl alcohol (dielectric constant: 11.4) was added to the aqueous slurry, and 10 ° C.
After stirring, the mixture was stirred at the same temperature for 2 hours. After stirring, this slurry was subjected to solid-liquid separation by filtration. The amount of Ba leaked into the filtrate was 1.0 mol% based on the charged amount. The obtained solid content (precipitate) was air-dried at 60 ° C. for 12 hours,
Calcination was performed at 50 ° C. for 1 hour to obtain BaTiO ₃ powder. X-ray diffraction analysis confirmed that it was BaTiO ₃ . The analytical value obtained by determining the molar ratio of Ba / Ti of the calcined powder by the glass bead method using X-ray fluorescence was as follows.
00.

The average particle size of the barium titanate powder measured by observation with an electron microscope was 0.2 μm, which was extremely fine and had a uniform composition.

[0041]

EXAMPLE 3 de CO ₂ ion-exchanged water 117 g, 1
5.78 g (0.05 mol) of Ba (OH) ₂ .8H ₂ O
Was added and heated to 80 ° C. to dissolve. This solution was cooled to 60 ° C. in a stream of N ₂ gas, and 1 mol / kg of titanium tetra i-propoxide [Ti (OiC ₃ H)
₇ ) 49.5 g of a toluene solution of [ ₄ ] [titanium tetra i-
14.1 g (0.0495 mol) as a propoxide, corresponding to a Ba / Ti molar ratio of 1.01] was added, and stirring was continued under reflux for 1 hour. Further heating at normal pressure (final temperature;
(To 100 ° C.) for about 1 hour, and toluene and i-propyl alcohol were distilled off. After adjusting the amount of water in the obtained slurry to 100 ml, 200 ml of tetrahydrofuran (dielectric constant 8.2) was added to the aqueous slurry, and the mixture was cooled to 10 ° C. and stirred for 2 hours. After stirring, this slurry was subjected to solid-liquid separation by filtration. The amount of Ba leaked into the filtrate was 1.0 mol% based on the charged amount. The resulting precipitate is
It was air-dried at 0 ° C. for 12 hours, and calcined at 850 ° C. for 1 hour to obtain BaTiO ₃ powder. X-ray diffraction analysis confirmed that it was BaTiO ₃ . The analysis value of the Ba / Ti molar ratio of the calcined powder determined by a glass bead method using fluorescent X-rays was 1.00.

The average particle diameter of the barium titanate powder measured by electron microscopy was 0.05 μm, which was extremely fine and had a uniform composition.

[0043]

[Comparative Example 1] 117 g of ion-exchanged water from which CO ₂ was removed
5.78 g (0.05 mol) of Ba (OH) ₂ .8H ₂ O
Was added and heated to 80 ° C. to dissolve. This solution was cooled to 60 ° C. in a stream of N ₂ gas, and 1 mol / kg concentration of titanium tetra n-butoxide [Ti (Onb
u) ₄ ] in 50.0 g of toluene solution [titanium tetra n
17.0 g (0.05 mol) of butoxide as Ba
/ Ti molar ratio is equivalent to 1.00], and 1
Stirring was continued for hours. Heating was further continued, and toluene and n-butyl alcohol were distilled off. After adjusting the amount of water in the obtained slurry to 100 ml, 100 ml of water (dielectric constant: 80.4) was added to the aqueous slurry, cooled to 10 ° C., and stirred for 2 hours. After stirring, the slurry was separated by filtration. The amount of Ba leaked into the filtrate was 1
It was 1.8 mol%. The resulting precipitate is dried at 60 ° C. for 12 hours.
Air drying for 1 hour, calcining at 850 ° C for 1 hour, Ba
TiO ₃ powder was obtained. X-ray diffraction analysis showed that B
It was confirmed to be aTiO ₃ . However, the analytical value obtained by determining the Ba / Ti molar ratio of the calcined powder by a glass bead method using fluorescent X-rays was 0.88.

The average particle size of such barium titanate powder measured by an electron microscope was as fine as 0.2 μm. However, since the Ba / Ti ratio analysis value was 0.88, Is a powder having an excessive composition.

[Brief description of the drawings]

FIG. 1 shows the powder (B) obtained in Example 1.
2 is an X-ray diffraction chart of aTiO ₃ ).

Claims (6)

[Claims] A titanium alkoxide is hydrolyzed by contacting barium hydroxide with water and a titanium alkoxide, and then a water-soluble organic solvent is added to the obtained reaction solution to remain as an unreacted substance in the reaction solution. A method for producing barium titanate powder, comprising reducing the solubility of dissolved barium ions and promoting the barium titanate generation reaction. 2. The barium titanate powder according to claim 1, wherein the contact between the barium hydroxide, the water and the titanium alkoxide is performed by mixing an aqueous barium hydroxide solution and a titanium alkoxide. Method. 3. The method for producing barium titanate powder according to claim 1, wherein the water-soluble organic solvent has a lower dielectric constant than that of water. 4. The method for producing barium titanate powder according to claim 1, wherein said water-soluble organic solvent has a dielectric constant of 40 or less. 5. The titanic acid according to claim 1, wherein the water-soluble organic solvent is at least one selected from acetone, t-butyl alcohol and tetrahydrofuran. A method for producing barium powder. 6. The method according to claim 1, wherein said titanium alkoxide is previously dissolved in an organic solvent.
6. The method for producing a barium titanate powder according to any one of items 1 to 5.