JPH06227817A - Fine granular powder of perovskite type compound - Google Patents

Abstract

PURPOSE:To obtain readily sinterable fine granular powder capable of providing ceramics composed of dense and fine grains by specifying the content of SO3 in fine granular powder of a barium titanate-based perovskite type compound. CONSTITUTION:This fine granular powder of a perovskite type compound has 0.03-0.10wt.% content of SO3 as an impurity and preferably 0.05-0.3mum grain diameter. The objective powder is synthesized by initially adding hydrochloric acid or nitric acid to a hydrous titanium oxide slurry with 0.1-0.3wt.% content of SO3, regulating the pH of the resultant slurry to <=1.5, adding an alkali to the obtained dispersion of titania sol, washing the dispersion, then adding hydroxide of an alkaline earth metal, further regulating the composition of the slurry to 0.1-0.8mol/l alkaline earth metal (M) and 1.2-1.5 molar ratio of MO/TiO2, heating the slurry to a higher temperature than the boiling point thereof and keeping the heated slurry at the temperature for 0.5-5hr.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to barium titanate-based perovskite type compound fine particle powder, which is characterized by being easily sinterable, and by which a ceramic composed of dense and fine grains can be obtained.

2. Description of the Related Art In recent years, electronic materials have become smaller and higher in performance.
_The same applies to the ferroelectric ceramics using a ₂ type perovskite type compound, and various studies have been conducted in terms of compounding technology, molding technology, sintering technology, etc. for the purpose of miniaturization and high performance. However, miniaturization and high performance have reached the limit only by such improvement of the technology, and it is said that it is necessary to improve the characteristics of the material itself in order to further reduce the size and the performance. That is, the development of spherical TiO ₂ -based perovskite-type compound powder having a diameter of 1 μm or less, preferably 0.5 μm or less, a narrow particle size distribution, has been earnestly desired. The development of the fine particle powder of the perovskite type compound having such properties has been earnestly desired for the following reasons. That is, if the particle size is small, the surface energy is high, and if the particle size is uniform, packing at the time of molding is improved, sinterability is significantly improved, and dense and high-strength ceramics are obtained at lower temperatures. This is because it is considered that not only the ceramics obtained but also ceramics having a grain size of 0.5 to 1 μm, which has the highest relative dielectric constant as a ferroelectric, can be obtained.

Although a wet synthesis method under normal pressure and a hydrothermal synthesis method have been proposed as methods for obtaining fine perovskite type compounds, fine particle powders obtained by these methods are solid phase method or oxalate method. Although it has the characteristic that dense ceramics can be obtained at a lower temperature than the powder obtained in 1., it has the highest relative permittivity of 1 μm as a ferroelectric.
It was not characterized by the fact that a fine ceramics consisting of the following grains was obtained.

Further, barium titanate obtained by the atmospheric pressure wet method does not undergo a sufficient reaction as compared with barium titanate obtained by a solid-phase reaction, and contains a large amount of structured water, resulting in crystal formation. You can only get bad things. Therefore, when barium titanate obtained by the atmospheric pressure wet method is used as a raw material for thin-film ceramics, when it is dispersed in a water system and a binder or the like is mixed, water-soluble components mixed in the barium titanate are mixed. Elute in water. For this reason, the ceramics obtained by sintering barium titanate have a nonuniform composition, and there is a drawback that there are many variations in physical properties and electrical properties (International Publication WO91 / 02).
697).

SO _{3 in} barium titanate powder forms barium sulfate, and since this compound is a paraelectric substance, the incorporation of this compound into barium titanate causes a change in the relative dielectric constant of the ceramics obtained from the powder. It has been said that the smaller the SO ₃ content of the barium titanate powder is, the more preferable it is from the viewpoint of not only the decrease but also the poor sinterability of the powder.

Problems to be Solved by the Invention As described above, the conventional fine particle powder of the perovskite type compound does not have a feature that it has a grain diameter of 1 μm or less and that high density ceramics can be obtained.
It has been desired to develop a new perovskite type compound powder which can obtain a ceramic having a high density and a fine grain of 1 μm or less at a low temperature.

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the content of SO ₃ as an impurity is 0.03 to 0.1.
0% by weight, preferably with an average particle size of 0.05 to 0.
The present invention has been completed by finding that the perovskite type compound fine particle powder having a particle size of 3 μm has desired characteristics.

The perovskite type compound powder of the present invention is
To a titania sol dispersion obtained by adding hydrochloric acid or nitric acid to a hydrous titanium oxide slurry having an SO ₃ content of 0.1 to 0.3% by weight and adjusting the pH of the slurry to 1.5 or less, After adding and washing an alkali, a hydroxide of an alkaline earth metal is added to make the composition of the slurry 0.2 to 0.8 mol / liter of an alkaline earth metal (hereinafter referred to as "M"), MO. / TiO ₂ (molar ratio) is adjusted to 1.2 to 1.5, and then the slurry is heated to a temperature equal to or higher than the boiling point and kept at the temperature for 0.5 to 5 hours for synthesis.

The hydrous titanium oxide having an SO ₃ content of 0.1 to 0.3% by weight is adsorbed on the hydrous titanium oxide by further washing the hydrolysis product of the aqueous solution of titanyl sulfate with water and then adding an alkali. It can be obtained by removing sulphate radicals. It can also be obtained by adding an appropriate amount of sulfuric acid to hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanium tetrachloride.

Since the hydrolysis product of the aqueous solution of titanyl sulfate forms large aggregates, when it is used as it is as a raw material for synthesizing perovskite type compounds, the particle size distribution is wide,
Only powder with poor sinterability can be obtained. Furthermore, when synthesizing a perovskite type compound by a wet reaction method under normal pressure,
The reaction rate is slow and a perovskite type compound having a stoichiometric composition cannot be obtained. Therefore, for the purpose of obtaining a perovskite type compound having a narrow particle size distribution and a stoichiometric composition, the SO ₃ content of hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate is 0.1 by washing. After adjusting to 0.3 wt%, hydrochloric acid or nitric acid is added to obtain titania sol. At this time, the pH of the slurry
Is suitably 1.5 or less. The size of the titania sol particles depends on the hydrolysis conditions, but is preferably 150 angstroms or less. That is, if the particle size of the titania sol is larger than this value, it is difficult to obtain a perovskite type compound having a stoichiometric composition, and it is not possible to obtain a perovskite type compound having a narrow particle size distribution.

Next, for the purpose of removing chlorine ions or nitrate ions adsorbed on the titania sol particles, an alkali is added to the dispersion liquid of the titania sol and then washed. The alkalis that can be used at this time are NaOH and KO.
H, NH ₄ OH and the like. The hydrous titanium oxide obtained in the above steps shows an anatase type peak as measured by X-ray diffraction. In addition to these, hydrous titanium oxide includes amorphous titanium and X
Some of them have a rutile type crystal structure as measured by line diffraction, but any titanium oxide hydrate can be used without any trouble.
It can be used as a source of O ₂ .

The titania sol having a rutile-type crystal structure is a fine sol of hydrous titanium oxide showing a peak of a rutile-type crystal as measured by X-ray diffraction, and its average diameter is usually 50 to 120 angstrom. . The sol is, for example, added as a seed crystal during the hydrolysis of an aqueous titanyl sulfate solution for the purpose of promoting the rutile conversion of titanium dioxide in the production of a sulfuric acid method titanium dioxide pigment, and is produced by the following method. To be done.

While maintaining the titanyl sulfate aqueous solution or titanium tetrachloride aqueous solution at 5 to 30 ° C., an aqueous alkaline solution such as sodium hydroxide is added to precipitate titanium hydrous oxide, and the precipitate is prepared at 60 to 80 ° C. for 1 to 10 ° C. Mature for hours.

Hydrous titanium oxide such as metatitanic acid or orthotitanic acid is dispersed in an aqueous solution of sodium hydroxide, heated at 80 ° C. to the boiling point for 1 to 10 hours, filtered and washed, and then in a hydrochloric acid solution at 80 ° C. ~ 1-1 at boiling point
Heat treatment for 0 hours.

In order to facilitate the washing operation of the titania sol, when a titania sol having an anatase type crystal structure is used as the TiO ₂ source, the pH of the slurry is 6%.
It is preferable to adjust the pH to around, and the pH of the slurry is preferably around 4 when a titania sol having a rutile type crystal structure is used.

NaOH or K as an alkali source added to the dispersion liquid of titania sol for the purpose of removing chlorine ions or nitrate ions adsorbed on the titania sol particles.
When OH is used, it is especially important that the pH of the slurry not exceed 7. That is, when the pH of the slurry is adjusted to 7 or more, Na ⁺ and K ⁺ are adsorbed on the hydrous titanium oxide, and thus the content of Na and K in the perovskite type compound synthesized is not preferable.

The alkaline earth metal hydroxide used in the present invention is generally a white solid containing water of crystallization, but it may be used as it is or may be dissolved in water in advance. Alkaline earth metal hydroxides easily react with carbon dioxide in the air to form carbonates, but since carbonates have a lower solubility in water than hydroxides, they can be removed from the reaction system of perovskite-type compounds. It is not preferable because it is present. Further, since it remains in the reaction product even after washing, it is difficult to adjust the composition. Further, the carbonate formed in the alkaline earth metal hydroxide aqueous solution grows as a separate particle different from the perovskite type compound particles, which leads to non-uniformity of the composition of the perovskite type compound particle powder, which is not preferable. Therefore, the alkaline earth metal hydroxide not only sufficiently forms the carbonate before being used for the reaction to remove the carbonate, but also the aqueous solution does not come into contact with carbon dioxide during the perovskite-type compound purification reaction and the washing step after the reaction. You need to be careful. It is sufficient to purify the alkaline earth metal hydroxide by a known method, and the synthetic reaction and washing of the perovskite type compound may be carried out under a nitrogen atmosphere.

The mixing ratio of the hydrous titanium oxide and the alkaline earth metal hydroxide is MO / TiO ₂ (molar ratio) of 1.2 to 1.
It is 5. That is, if the mixing ratio is less than 1.2, the reaction rate is slow, which is not preferable, and if the molar ratio is more than 1.5, the reaction rate is not particularly high and is meaningless.

The concentration of alkaline earth metal hydroxide is 0.2
The range of up to 0.8 mol / liter is preferred. That is, if the concentration is less than 0.2 mol / liter, not only the reaction requires a long time, but also the composition of the obtained reaction product varies from lot to lot, which is not preferable. Further, the particle size of the synthesized perovskite type compound is larger than 0.3 μm, and it is difficult to obtain a high-density ceramic having a grain size of 1 μm or less from a powder having such a particle size. Is.

There is no particular problem as long as the reaction temperature for synthesizing the perovskite type compound is not lower than the boiling point. However, if the reaction temperature becomes higher, a reaction vessel having a higher pressure is required, which is not preferable. The range is appropriate.

The barium titanate compound of the invention includes B
aTiO ₃ is included. However, Ba is partially substituted by zero, one or more elements selected from Ca, Sr and Mg, and Ti is Z
zero, one, or two selected from r and Sn
It is partially replaced by the seed element.

In order to synthesize a barium titanate compound in which part of Ba is partially substituted with Ca, Sr, Mg or the like, the perovskite type compound is synthesized in a mixed aqueous solution of Ba and the above element. I'll do it.

In order to synthesize a barium titanate compound in which a part of Ti is partially substituted with Zr or Sn, or these two elements, a chloride of the above element is added after the titania sol is prepared, After that, alkali is added to the titania sol dispersion and then washed, and used as a raw material for synthesizing perovskite type compound as a mixture of hydrous titanium oxide and hydrous oxide of these elements.

As described above, the reaction of the perovskite type compound synthesized by the wet method under normal pressure does not proceed sufficiently, and the perovskite type compound itself has poor crystallinity.
Therefore, when dispersed in an aqueous system and blended with a binder or the like, the alkaline earth metal component mixed as a water-soluble component in the perovskite type compound powder is eluted into water, and the alkaline earth metal is molded and dried. Since it is precipitated in the process, the resulting ceramic has a non-uniform composition, and the physical properties and electrical properties vary widely. In order to solve this drawback, in the present invention, the water-soluble alkaline earth metal component present on the surface of the perovskite type compound particles synthesized by the wet method under normal pressure is changed to a carbonate having a low solubility in water. Therefore, in the present invention, the entire surface of the compound particles is not coated with the carbonate, but only the portion of the water-soluble alkaline earth metal component is converted into the carbonate and is present on the surface of the particle.

In order to convert the water-soluble alkaline earth metal component present on the surface of the perovskite-type compound particles synthesized by the wet method under normal pressure into a carbonate having a low solubility in water, the perovskite-type compound is mixed with a carbon dioxide gas. , Easily by contacting with air, carbon dioxide, or the like. At this time, it is possible to effectively perform the treatment in a shorter time by using the carbon dioxide gas containing high humidity. Therefore, it is also an effective treatment method to use a carbon dioxide-containing gas as a carrier gas for water during drying. However,
When the amount of alkaline earth metal dissolved in the aqueous solution is large, for example, when the carbon dioxide gas is brought into contact with the slurry at the end of the reaction, or the slurry in the initial stage of cleaning, etc.,
It is not preferable because single particles of alkaline earth metal carbonate are formed on a place other than the surface of the perovskite type compound particles, which not only causes nonuniformity of the composition but also makes it difficult to control the composition of the reaction product. By this treatment, an alkaline earth metal carbonate is formed on the surface of the perovskite type compound particles, and the C content contained in the perovskite type compound powder becomes about 0.1 to 0.4% by weight.

The present invention will be described in more detail with reference to examples. The following examples are given for illustrative purposes only and the scope of the invention is not limited thereby.

Example 1 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant became 1600 μS / cm, and then sodium hydroxide was added until the pH of the slurry became 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity of the supernatant became 200 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid to adjust the pH of the dispersion liquid to 6, and then the supernatant liquid was washed with pure water until the electric conductivity became 130 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern. Further, the SO of the dried hydrous titanium oxide examined by chemical analysis
_{The 3} content was found to be 0.25% by weight.

3200 g of hydrous titanium oxide having a water content of 92% thus obtained was transferred to a SUS reaction container,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O was added 1339G, further pure water was added to B
The slurry was adjusted to have aO of 0.20 mol / liter and a BaO / TiO ₂ molar ratio of 1.30. The slurry is heated to a boiling point at a heating rate of 79 ° C./H in a nitrogen atmosphere at a boiling point of 3 ° C.
The reaction was carried out over time. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained is 110 ° C.
Dried under vacuum and in air. Both products were examined by X-ray diffraction and found to be a single phase of barium titanate. Particles other than barium titanate were not particularly observed even when observed under an electron microscope. The C content of the powder dried under vacuum was 0.04% by weight and that of the powder dried in air was 0.07% by weight. SO _{3 of} powder dried under vacuum and powder dried in air
The content was both 0.08% by weight. The average particle size calculated by weight distribution by PSA using an electron micrograph was 0.19 μm. The Na content of the powder is 5
It was ppm. The BaO / TiO ₂ molar ratio of the powder was 0.999. Further, the powder was allowed to stand in a carbon dioxide gas atmosphere having a relative humidity of 100% for 4 hours and then examined by X-ray diffraction. As a result, barium carbonate was identified in addition to barium titanate. The C content of the powder was 0.36% by weight.
The barium elution amount of the vacuum dried powder, the dry powder in the air and the powder left in the carbon dioxide atmosphere with respect to water at 25 ° C. are shown in the table below. It can be seen that the elution amount of barium from the powder left in the carbon dioxide atmosphere is small.

Ba concentration (mol / liter) Vacuum dried powder 9.8 × 10^-4 Dry powder in air 8.3 × 10^-4 Powder left in carbon dioxide atmosphere 0.5 × 10^-4 Example 2 ． Obtained by hydrolyzing an aqueous solution of titanyl sulfate
The electrical conductivity of the supernatant liquid of hydrous titanium oxide is 1200μ
After washing with pure water until S / cm, p of the slurry
Add sodium hydroxide solution until H is 9.5
It was Further, add hydrochloric acid to the slurry to adjust the pH of the slurry.
After adjusting to 7, the electrical conductivity of the supernatant of the slurry
Was washed with pure water until it reached 250 μS / cm.
Then, add hydrochloric acid to the slurry to adjust the pH of the slurry to 1
To obtain a titania sol dispersion liquid. The titania sol
An aqueous solution of sodium hydroxide was added dropwise to the dispersion to obtain the dispersion.
After adjusting the pH to 6 the electrical conductivity of the supernatant is 170
It was washed with pure water until it became μS / cm. Hydrous acid obtained
The titanium oxide was dried at 110 ° C and examined by X-ray diffraction.
The diffraction pattern of the anatase was shown. Also, the chemical
SO of the dried hydrous titanium oxide, as determined by precipitation₃The content rate is
It was found to be 0.27% by weight.

6400 g of hydrous titanium oxide having a water content of 94% thus obtained was transferred to a SUS reaction vessel,
After flowing nitrogen gas in the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O was added 2008G, further pure water was added to B
The slurry was adjusted to have aO of 0.30 mol / liter and a BaO / TiO ₂ molar ratio of 1.30. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 81 ° C./H and reacted at the boiling point for 2.5 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Particles other than barium titanate were not particularly observed even when observed under an electron microscope. C of the powder
Content is 0.06% by weight, SO ₃ content is 0.0
It was 8% by weight. The average particle size was 0.09 μm. The BaO / TiO ₂ molar ratio of the powder was 1.002.

Example 3 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant became 1200 μS / cm, and then sodium hydroxide was added until the pH of the slurry became 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity of the supernatant became 290 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid to adjust the pH of the dispersion liquid to 6, and then the supernatant liquid was washed with pure water until the electric conductivity of the supernatant liquid became 120 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern.
Further, S of the dried hydrous titanium oxide, which was examined by chemical analysis,
The O ₃ content was found to be 0.20% by weight.

2793 g of hydrous titanium oxide having a water content of 89% thus obtained was transferred to a SUS reaction vessel,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O was added 1647G, further pure water was added to B
The slurry was adjusted to have aO of 0.24 mol / liter and a BaO / TiO ₂ molar ratio of 1.33. The slurry is heated to the boiling point at a heating rate of 83 ° C./H in a nitrogen atmosphere at a boiling point of 4 ° C.
The reaction was carried out over time. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Also, no particles other than barium titanate were observed even under an electron microscope. C of the powder
Content is 0.07% by weight, SO ₃ content is 0.0
It was 6% by weight. The average particle size was 0.16 μm. The BaO / TiO ₂ molar ratio of the powder was 1.000.

Example 4 After adding 0.15% by weight of sulfuric acid as SO ₃ to TiO ₂ in the titania sol dispersion obtained by hydrolyzing an aqueous solution of titanium tetrachloride, an aqueous sodium hydroxide solution is added until the pH of the slurry reaches 6. did. The electric conductivity of the supernatant of the slurry is 170 μS
It was washed with pure water until it became / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, it showed a diffraction pattern of anatase.

4.80 mol of hydrous titanium oxide having a water content of 89% thus obtained was transferred to a reaction vessel made of SUS, and nitrogen gas was allowed to flow into the reaction vessel for 20 minutes.
(OH) ₂ · 8H ₂ O6.24 moles added, BaO0.30 mole / liter and further adding pure water, BaO / TiO ₂
The slurry was adjusted to a molar ratio of 1.30. In a nitrogen atmosphere, the slurry was heated to the boiling point at a temperature rising rate of 85 ° C./H and reacted at the boiling point for 2 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Also, no particles other than barium titanate were observed even under an electron microscope. The C content of the powder was 0.07% by weight, and the SO ₃ content was 0.05% by weight. The average particle size is 0.12μ
It was m. The powder has a BaO / TiO ₂ molar ratio of 0.9.
It was 98.

Example 5 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant became 1500 μS / cm, and then sodium hydroxide was added until the pH of the slurry became 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity of the supernatant became 290 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid to adjust the pH of the dispersion liquid to 6, and then the supernatant liquid was washed with pure water until the electric conductivity of the supernatant liquid became 120 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern.
Further, S of the dried hydrous titanium oxide, which was examined by chemical analysis,
The O ₃ content was found to be 0.28% by weight.

4371 g of hydrous titanium oxide having a water content of 93% thus obtained was transferred to a SUS reaction container,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O1236g and Ca (OH) ₂ 72.6g
Was added, and then pure water was added to obtain 0.25 mol / liter of BaO + CaO and a (BaO + CaO) / TiO ₂ molar ratio of 1.
The slurry was adjusted to 20. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 79 ° C./H and reacted at the boiling point for 3 hours. After the reaction, cool until the liquid temperature reaches 40 ° C,
It was washed by decantation with pure water in a nitrogen atmosphere and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. When the product was examined by X-ray diffraction, it was found that the peak was shifted to a higher angle side than the peak position of barium titanate. The C content of the powder was 0.08% by weight and the SO ₃ content was 0.09.
% By weight. The average particle size was 0.17 μm. (BaO + CaO) of the powder obtained by fluorescent X-ray
The / TiO ₂ molar ratio was 1.000.

Example 6 The hydrous titanium oxide obtained by hydrolyzing the aqueous titanyl sulfate solution was washed with pure water until the electric conductivity of the washing water reached 1700 μS / cm, and sodium hydroxide was added until the pH of the slurry reached 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and then the supernatant liquid of the slurry was washed with pure water until the electric conductivity thereof became 210 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid to adjust the pH of the dispersion liquid to 6, and then the supernatant liquid was washed with pure water until the electric conductivity of the supernatant liquid became 120 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern.
Further, S of the dried hydrous titanium oxide, which was examined by chemical analysis,
The O ₃ content was found to be 0.29% by weight.

[0038] 4571 g of hydrous titanium oxide having a water content of 93% thus obtained was transferred to a SUS reaction container,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O1339g and Sr (OH) ₂ 282g was added, further added with pure water BaO + SrO0.25 mol /
Liter, (BaO + SrO) / TiO ₂ molar ratio 1.3
The slurry was adjusted to 0. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 79 ° C./H and reacted at the boiling point for 3 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. When the product was examined by X-ray diffraction, it was found that the peak was shifted to a higher angle side than the peak position of barium titanate. The C content of the powder was 0.05% by weight and the SO ₃ content was 0.08% by weight. The average particle size was 0.15 μm. (BaO + SrO) of the powder obtained by fluorescent X-ray
The / TiO ₂ molar ratio was 1.002.

Example 7 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant became 1400 μS / cm, and then sodium hydroxide was added until the pH of the slurry became 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity was 190 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid to adjust the pH of the dispersion liquid to 6, and then the supernatant liquid was washed with pure water until the electric conductivity became 150 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern.
Further, it was found by chemical analysis that the titanium hydroxide had an SO ₃ content of 0.26% by weight.

4800 g of hydrous titanium oxide having a water content of 92% thus obtained was transferred to a SUS reaction vessel,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O1483g and Mg (OH) ₂ 68.6g
Was added, and pure water was further added to obtain BaO + MgO 0.30 mol / liter and a (BaO + MgO) / TiO ₂ mol ratio of 1.
The slurry was adjusted to 20. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 83 ° C./H and reacted at the boiling point for 3 hours. After the reaction, cool until the liquid temperature reaches 40 ° C,
It was washed by decantation with pure water in a nitrogen atmosphere and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. When the product was examined by X-ray diffraction, it was found that the peak was shifted to a higher angle side than the peak position of barium titanate. The C content of the powder was 0.09% by weight and the SO ₃ content was 0.08.
% By weight. The average particle size was 0.14 μm. (BaO + MgO) of the powder obtained by fluorescent X-ray
The / TiO ₂ molar ratio was 1.003.

Example 8 . The hydrous titanium oxide obtained by hydrolyzing the aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant liquid reached 1500 μS / cm, and then the aqueous sodium hydroxide solution until the pH of the slurry reached 9.5. Was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant liquid of the slurry was washed with pure water until the electric conductivity of the slurry became 170 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. 0.25 mol of zirconium oxychloride was added to 1 mol of TiO ₂ in the titania sol dispersion, and thereafter,
A sodium hydroxide aqueous solution was added until the pH of the dispersion became 6, to obtain a mixed slurry of hydrous titanium oxide and hydrous zirconium oxide. The supernatant of the slurry was washed with pure water until the electric conductivity of the supernatant reached 190 μS / cm. When the obtained hydrous oxide was dried at 110 ° C. and examined by chemical analysis, it was found that the SO ₃ content was 0.27% by weight.

1330 g of hydrous titanium oxide having a water content of 96% thus obtained was transferred to a SUS reaction vessel,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O251g was added and adjusted further by adding pure water liquid volume 2 liters. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 79 ° C./H and reacted at the boiling point for 3 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. When the product was examined by X-ray diffraction, it was found that the peak shifted to a lower angle side from the peak position of barium titanate. The C content of the powder was 0.08% by weight and the SO ₃ content was 0.06% by weight. The average particle size was 0.13 μm. BaO / (TiO ₂ of the powder obtained by X-ray fluorescence
The + ZrO ₂ ) molar ratio was 0.998.

Example 9 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant became 1700 μS / cm, and then sodium hydroxide was added until the pH of the slurry became 9.5. Aqueous solution was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity of the supernatant became 270 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. 0.25 with respect to 1 mol of TiO ₂ in the titania sol dispersion liquid
A molar equivalent amount of stannic chloride was added, and then a sodium hydroxide aqueous solution was added until the pH of the dispersion became 6.6 to obtain a mixed slurry of titanium oxide hydroxide and tin oxide hydroxide. The electric conductivity of the supernatant of the slurry is 290 μS.
It was washed with pure water until it became / cm. The obtained hydrous oxide was dried at 110 ° C. and examined by chemical analysis.
_{The 3} content was found to be 0.24% by weight.

942 g of the hydrous oxide having a water content of 95% obtained as described above was transferred to a SUS reaction vessel, and nitrogen gas was passed through the reaction vessel for 20 minutes, and then Ba (OH) ₂ ·.
8H ₂ O (193 g) was added, and pure water was further added to adjust the liquid volume to 2 liters. In a nitrogen atmosphere, the slurry was heated to the boiling point at a heating rate of 80 ° C./H and reacted at the boiling point for 3 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The obtained cake is 110 in the atmosphere.
It was dried at ° C. When the product was examined by X-ray diffraction, it was found that the peak shifted to a lower angle side from the peak position of barium titanate. The C content of the powder was 0.07% by weight and the SO ₃ content was 0.07% by weight.
Met. The average particle size was 0.16 μm. BaO / (TiO ₂ + Sn) of the powder obtained by fluorescent X-ray
The O ₂ ) molar ratio was 1.001.

Comparative Example 1 . The hydrous titanium oxide obtained by hydrolyzing the aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant liquid reached 1600 μS / cm, and then the aqueous sodium hydroxide solution was added until the pH of the slurry reached 10. After the addition, the product was washed with pure water so that the SO ₃ content was 0.
A hydrous titanium oxide having an X-ray diffraction pattern of 07% by weight of anatase was obtained. When this hydrous titanium oxide was examined under an electron microscope, it was found to form large aggregates.

2560 g of hydrous titanium oxide having a water content of 90% thus obtained was transferred to a SUS reaction container,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O1339g added, further pure water was added to B
The slurry was adjusted to have aO of 0.20 mol / liter and a BaO / TiO ₂ molar ratio of 1.30. The slurry is heated to a boiling point at a heating rate of 79 ° C./H in a nitrogen atmosphere at a boiling point of 3 ° C.
The reaction was carried out over time. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Also, no particles other than barium titanate were observed even under an electron microscope. C of the powder
Content is 0.08% by weight, SO ₃ content is 0.0
It was 2% by weight. The average particle size was 0.19 μm. The BaO / TiO ₂ molar ratio of the powder was 0.999.

Comparative Example 2 The hydrous titanium oxide obtained by hydrolyzing the aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the supernatant liquid reached 1300 μS / cm, and then the aqueous sodium hydroxide solution was added until the pH of the slurry reached 8. Was added. Further, hydrochloric acid was added dropwise to the slurry to adjust the pH of the slurry to 7, and the supernatant of the slurry was washed with pure water until the electric conductivity of the slurry became 190 μS / cm. Then, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1 to obtain a titania sol dispersion liquid. An aqueous sodium hydroxide solution was added dropwise to the titania sol dispersion liquid,
After adjusting the pH of the dispersion to 6, the supernatant was washed with pure water until the electric conductivity of the supernatant became 150 μS / cm. When the obtained hydrous titanium oxide was dried at 110 ° C. and examined by X-ray diffraction, it showed anatase diffraction pattern. Further, the SO of the dried hydrous titanium oxide examined by chemical analysis
_{The 3} content was found to be 0.45% by weight.

3200 g of the hydrous titanium oxide having a water content of 92% thus obtained was transferred to a SUS reaction container,
After flowing nitrogen gas into the reaction vessel for 20 minutes, Ba (O 2
H) ₂ · 8H ₂ O1339g added, further pure water was added to B
The slurry was adjusted to have aO of 0.20 mol / liter and a BaO / TiO ₂ molar ratio of 1.30. The slurry is heated to a boiling point at a heating rate of 81 ° C./H in a nitrogen atmosphere at a boiling point of 3 ° C.
The reaction was carried out over time. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Also, no particles other than barium titanate were observed even under an electron microscope. C of the powder
Content is 0.08% by weight, SO ₃ content is 0.1
It was 5% by weight. The average particle size was 0.18 μm. The BaO / TiO ₂ molar ratio of the powder was 1.003.

Comparative Example 3 After adding 0.06 wt% sulfuric acid as SO ₃ to TiO ₂ in the titania sol dispersion obtained by hydrolyzing the titanium tetrachloride aqueous solution, an aqueous sodium hydroxide solution is added until the pH of the slurry becomes 6. did. The slurry was washed with pure water until the electric conductivity of the slurry reached 150 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, it showed a diffraction pattern of anatase.

4.80 mol of hydrous titanium oxide having a water content of 89% thus obtained was transferred to a SUS reaction vessel, and nitrogen gas was allowed to flow into the reaction vessel for 20 minutes.
(OH) ₂ · 8H ₂ O6.24 moles added, BaO0.30 mole / liter and further adding pure water, BaO / TiO ₂
The slurry was adjusted to a molar ratio of 1.30. The slurry was heated up to the boiling point at a heating rate of 83 ° C./H in a nitrogen atmosphere, and reacted at the boiling point for 2 hours. After the reaction, the solution was cooled to a temperature of 40 ° C., washed with decantation using pure water in a nitrogen atmosphere, and then filtered. The cake obtained was dried at 110 ° C. in the atmosphere. The product was examined by X-ray diffraction and found to be a single phase of barium titanate. Also, no particles other than barium titanate were observed even under an electron microscope. The C content of the powder was 0.06% by weight and the SO ₃ content was 0.01% by weight. The average particle size is 0.11μ
It was m. The BaO / TiO ₂ molar ratio of the powder was 0.998.

The powders obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were molded under a pressure of 1 t / cm ² to obtain a green molded body, which was fired at a predetermined temperature for 2 hours to prepare a sintered body. The sintered density of the sintered body was measured by the Archimedes method, and Ag paste was baked on the sintered body to form an electrode, and the relative dielectric constant was measured. Further, the sintered body was mirror-polished to measure the grain diameter. The results are shown in the table below. In addition, as a reference, the evaluation results of BT-01 manufactured by Sakai Chemical Industry and BTWS-1 manufactured by Fuji Titanium Industry at our company are also shown in the table below.

BT-01 manufactured by Sakai Chemical Industry has a C content of 0.17 wt% and an SO ₃ content of 0.01 wt%.
% Or less, and the average particle size was 0.11 μm. The BaO / TiO ₂ molar ratio was 1.000. Fuji Titanium Industry BTWS-1 has a C content of 0.16 wt.
%, The SO ₃ content is 0.01 wt% or less,
The average particle size was 0.15 μm. In addition, BaO / Ti
The O ₂ molar ratio was 0.998.

[0053]

Claims (3)

[Claims] 1. A SO ₃ content of 0.03 to 0.10% by weight.
Barium titanate-based perovskite-type compound fine particles powder characterized by: 2. The barium titanate-based perovskite-type compound fine particle powder according to claim 1, which has an average particle diameter of 0.05 to 0.30 μm. 3. The barium titanate-based perovskite-type compound fine particle powder according to claim 1, wherein a carbonate of an alkaline earth metal is present on the surface of the particle.