JPH06305729A - Fine powder of perovskite type compound and its production - Google Patents

Abstract

PURPOSE:To provide fine powder of a strontium titanate-based perovskite type compd. capable of sintering at a low temp. and giving a high density sintered compact having a small grain diameter. CONSTITUTION:This fine powder of a strontium titanate-based perovskite type compd. has 0.03-0.3mum average particle diameter and <=0.2 as a value given by dividing the quarter-deviation by the average particle diameter and contains 0.04-0.14wt.% SO3.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strontium titanate-based perovskite type compound fine particle powder which is characterized by being easily sinterable and being capable of obtaining a fine and fine grain ceramic.

2. Description of the Related Art In recent years, electronic materials have become smaller and higher in performance.
_The same applies to ferroelectric ceramics using a _2- system 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. In particular, in the field of grain boundary insulation type semiconductor capacitors, the apparent relative permittivity can be greatly improved by reducing the size of ceramic grains from several tens of μm to 1 μm or less. It is said that a smaller size and a larger capacity can be achieved because the thickness can be further reduced when laminated. That is, 1
The development of spherical strontium titanate powder having a diameter of less than or equal to μm, preferably less than or equal to 0.5 μm, a narrow particle size distribution, and a spherical shape has been earnestly desired. The development of fine particle powder of perovskite type compound having such properties is earnestly desired because the smaller the particle size is, the higher the surface energy is, and the uniform particle size is, the better the packing at the time of molding is. It is believed that the sinterability is remarkably improved and dense high-strength ceramics can be obtained at a lower temperature. In addition to this, as the use of the fine particle powder of the perovskite type compound, application to a liquid crystal surface film additive material and a copier developer additive material is expected.

From the above viewpoint, fine particles of TiO ₂
The powders of the perovskite-based compound or the production method thereof have been actively developed, but similar attempts have been made for strontium titanate. For example, Japanese Unexamined Patent Publication No. 59-45928 discloses a method of reacting a hydrolysis product of a titanium compound with a water-soluble strontium salt in a strong alkaline aqueous solution to obtain strontium titanate fine particles. However, in the manufacturing method, it is difficult to remove the alkali added during the synthesis in the washing step, and not only the problem that the added alkali component is mixed into the synthetic powder as an impurity, but the particles are too small as 100 to 200 angstroms to be added. There is a problem that it is difficult to uniformly disperse it in the slurry when mixing with a substance.

Japanese Patent Laid-Open Publication No. 61-146711 discloses a method of obtaining a barium strontium titanate solid solution powder by reacting a Ti hydrolysis product, a water-soluble Ba salt and an Sr salt in a strong alkaline aqueous solution. Japanese Unexamined Patent Publication No. 61-146712 discloses a method of obtaining a barium-strontium titanate solid solution powder by reacting hydrous titanium oxide with Ba salt or the like in the presence of water. . In addition, Japanese Patent Laid-Open No. Sho 61-
Japanese Patent No. 146713 discloses hydrous titanium oxide, Ba (O
Disclosed is a method of reacting H) ₂ , Sr (OH) ₂ , and an alkali metal hydroxide in the presence of water to obtain a barium strontium titanate solid solution powder. Further, Japanese Laid-Open Patent Publication No. 62-72525 discloses a method in which a Ba or Sr compound is dissolved in TiCl ₄ , and NaOH or the like is added thereto to cause a hydrothermal reaction to obtain barium titanate or strontium titanate powder. However, in all of the above-mentioned production methods, it is difficult to remove the alkali added at the time of synthesis in the washing step, as in Japanese Patent Laid-Open No. 59-45928, and there is a problem that the added alkali component is mixed as an impurity in the synthetic powder. have.

Japanese Unexamined Patent Publication No. 61-146709 discloses a strontium titanate powder which can be sintered at a low temperature, having an average particle size of 0.07 to 0.5 μm and a specific surface area of 3 to.
The value is 20 m ² / g and does not exceed 2.5 times the value calculated from the average particle diameter assuming that the particle shape is a true sphere.
Disclosed is a strontium titanate powder having a crystallite diameter of 0.05 μm or more and 0.4 μm or less calculated from the half width of the peak of a line diffraction image and having a spherical shape. The strontium titanate powder is synthesized by heating titanium oxide hydrate, strontium hydroxide and water while stirring and mixing in a nitrogen atmosphere at 60 ° C. or higher and lower than 110 ° C. The powder has a sintering temperature of 1200 ° C., which is lower by 100 ° C. or more than the known strontium titanate powder,
It is said that a sintered body having a uniform microstructure is provided. However, when strontium titanate is used in a ceramic capacitor, it is necessary to use an electrode material containing a large amount of Pd in order to increase the baking temperature of the electrode as the temperature required for sintering is higher, which reduces the cost of the electrode. Further lowering of the sintering temperature was desired in order to raise the temperature.
Further, there is a problem that particles are likely to grow during sintering and the grain diameter of the obtained sintered body becomes large.

Japanese Unexamined Patent Publication No. 60-90825 discloses a method for removing excess Sr by using a wet reaction product.
Although a method of calcination at a temperature of 000 ° C or lower and washing with a weak acid is disclosed, this method is for the purpose of reproducibly obtaining strontium titanate having a specific composition near the stoichiometric composition. It cannot be an effective means. Further, in this method, since only the surface of the particles is washed with acetic acid to form a Ti-excessive composition, the sinterability is remarkably reduced.

[0007] The published patent publication WO 91/02697 discloses a method for converting strontium titanate having poor crystallinity obtained by the atmospheric pressure heating reaction method into strontium titanate having good crystallinity by the atmospheric pressure heating reaction method. The synthesized SrO / TiO ₂ (molar ratio) was from 1000 to 1100 from strontium titanate powder having a composition of from 1.01 to 1.40.
It discloses a method of dissolving and removing excess Sr with an acid after heating to ° C. However, this method is not a preferable method for synthesizing strontium titanate having a specific composition, for example, a stoichiometric composition with good reproducibility. That is, S
Strontium titanate powder having a composition of rO / TiO ₂ (molar ratio) of 1.01 to 1.40 was heated to 1000 to 1100 ° C.
When heated to, the reaction product changes to a two-phase mixture of strontium titanate (SrTiO ₃ ) and Sr ₂ TiO ₄ , and Sr in Sr ₂ TiO ₄ is easily dissolved in the acid in the next acid treatment step. Since Ti does not dissolve in acid and remains in strontium titanate as hydrous titanium oxide, it is difficult to synthesize strontium titanate powder having a stoichiometric composition with good reproducibility.

Japanese Laid-Open Patent Publication No. 61-31345 discloses that the above problems can be solved by a method of converting Sr ²⁺ dissolved in an aqueous solution into a water-insoluble form, followed by filtration, washing with water and drying. However, although the strontium titanate powder obtained by the publication has an apparent stoichiometric composition, it is not a single layer of strontium titanate, but strontium titanate produced by the reaction, unreacted titanium compound and water-insolubilized 3 is a three-phase mixture of the prepared strontium compound. Therefore, the ceramic mix obtained by sintering the strontium titanate powder has a non-uniform composition, and thus tends to be a sintered body containing abnormally grown particles, which causes variations in physical properties and electrical properties. There were many drawbacks. Furthermore, since an expensive pressure vessel is used as a reaction vessel when synthesizing the strontium titanate, there is a problem that the manufacturing cost becomes high.

An object of the present invention is to provide a ferroelectric ceramic which can obtain a ceramic having a high density and fine grains at a lower temperature, which is not possessed by conventional fine particle powders of perovskite type compounds. Is to provide a novel perovskite type compound powder.

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the average particle size is 0.03 to 0.3 μm and the particle size distribution has a quartile deviation of the average particle size. They have found that a perovskite type compound fine particle powder having a value divided by a diameter of 0.2 or less and containing 0.04 to 0.14% by weight of SO ₃ can realize desired characteristics, and thus completed the present invention. Is.

The perovskite type compound fine particle powder of the present invention has an average particle size of 0.03 to 0.3 μm measured by a transmission electron microscope observation, and all particles have substantially the same particle size. The value obtained by dividing the quartile deviation by the average particle diameter is 0.2 or less. The average particle size is 50% of the weight standard measured by the equivalent circular diameter from the transmission electron micrograph.
The particle size is the particle size, and the quartile deviation is 75% of the weight-based particle size measured by the equivalent circular diameter from the transmission electron micrograph and 25%.
It is represented by the difference in% particle size.

In the case of a powder having an extremely small particle size such as the fine particle powder of the present invention, it is practically impossible to adjust the particle size distribution by a known means such as classification after the powder is manufactured. Sometimes it is necessary to produce a powder with a sharp distribution.

The fine particles of perovskite-type compound of the present invention are prepared by adding hydrochloric acid or nitric acid to a hydrous titanium oxide slurry to adjust the pH of the slurry to 1.5 or less, and then adding an alkali to a titania sol dispersion. After addition, washing is performed, and Sr hydroxide is added to change the composition of the slurry to
Hydrous titanium oxide 0.1 to 0.8 mol / liter, preferably 0.2 to 0.5 mol / liter, and the mixing ratio of Sr and hydrous titanium oxide is 0.9 to 1.2, preferably 0. .95 to 1.10, and then the slurry is heated to a reaction temperature of 50 ° C. or more at a heating rate of 40 ° C. or less per hour and kept at the reaction temperature for 0.5 to 5 hours. Is synthesized by.

The SO ₃ content is 0.1 to TiO ₂ .
When synthesized using a hydrous titanium oxide slurry of 0.3% by weight, fine perovskite type compound fine particles powder containing 0.04 to 0.14% by weight of SO ₃ can be obtained. SO
_As compared with the case where ₃ is not contained, a finer ceramic having finer grains of 1 μm or less can be obtained.
Although SO ₃ is an impurity, it is believed that its presence hinders grain growth during sintering and reduces the grain size of the obtained sintered body. That is, an unexpected effect was obtained by including SO ₃ as a impurity in a certain amount or more, which has been conventionally sought to reduce the content as much as possible.

The SO ₃ content is 0.1 to TiO ₂ .
Titanium oxide hydroxide of 0.3% by weight can be obtained by washing the hydrolysis product of the titanyl sulfate aqueous solution with water and then adding an alkali to remove the sulfate radicals adsorbed on the titanium oxide hydroxide. it can. 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 titanyl sulfate aqueous solution forms large aggregates, if it is used as it is as a raw material for synthesizing the perovskite type compound, the particle size distribution is wide,
Only powder with poor sinterability can be obtained. Then, for the purpose of obtaining a perovskite type compound having a narrow particle size distribution and a desired ratio of alkaline earth metal and TiO _{2 in the} vicinity of the stoichiometric composition, it was obtained by hydrolyzing an aqueous titanyl sulfate solution. The SO ₃ content of hydrous titanium oxide is adjusted to 0.1 to 0.3% by weight with respect to TiO ₂ by washing, and then hydrochloric acid or nitric acid is added to obtain a titania sol. At this time, the pH of the slurry is preferably 1.5 or less.

The size of the titania sol particles depends on the hydrolysis conditions, but is preferably 300 angstroms or less. When it is larger than this value, it becomes difficult to obtain a perovskite type compound having a narrow particle size distribution.

Then, an alkali is added to the dispersion liquid of the titania sol for the purpose of removing the chlorine ions or the nitrate ions adsorbed on the titania sol particles. The alkalis that can be used at this time are NaOH, KOH, NH ₄ OH.
Etc. The hydrous titanium oxide obtained in the above steps shows an anatase type peak as measured by X-ray diffraction. In addition to these, there are amorphous hydrous titanium oxides and those exhibiting a rutile type crystal structure as measured by X-ray diffraction.

The titania sol having a rutile-type crystal structure is a sol of minute 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. For example, this sol is 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. It can be manufactured.

A) 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 hydrous titanium oxide, and the precipitation is conducted at 60 to 80 ° C. Aged for 10 hours.

B) Hydrous titanium oxide such as metatitanic acid or orthotitanic acid is dispersed in an aqueous solution of sodium hydroxide, and heat-treated at 80 ° C. to boiling point for 1 to 10 hours.
Filter and wash, then in hydrochloric acid solution at 80 ° C-boiling point 1-
Heat treatment for 10 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 a 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.

Incidentally, NaOH or K is used as an alkali source to be 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. This is because if the pH of the slurry is adjusted to 7 or more, Na ⁺ and K ⁺ are adsorbed on the hydrous titanium oxide and the content of Na and K in the perovskite type compound synthesized is increased, which 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 used by dissolving it in water beforehand. 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 is not only sufficiently purified to remove the carbonate before being subjected to the reaction, but also the aqueous solution does not come into contact with carbon dioxide during the perovskite-type compound formation 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 strontium hydroxide and hydrous titanium oxide is 0.9 to 1.2 in terms of the molar ratio of Sr / TiO ₂ . That is, in the case of a strontium titanate-based perovskite-type compound, the reaction easily proceeds to an excess composition of strontium, so that the composition of the obtained powder is almost the same as the above mixing ratio. Therefore, if the mixing ratio of the desired Sr / TiO ₂ molar ratio is set near the stoichiometric composition, the perovskite type compound fine particle powder having the desired composition can be obtained.

The concentration of strontium hydroxide is 0.1-0.1%.
A range of 0.8 mol / liter is preferred. That is, when the concentration is less than 0.1 mol / liter, not only the reaction requires a long time, but also the composition of the obtained reaction product varies greatly 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. On the other hand, if the concentration is higher than 0.8 mol / liter, the viscosity of the slurry becomes large and stirring becomes difficult, which is not preferable.

The reaction temperature of the perovskite type compound is 50.
There is no particular problem as long as the temperature is at least ℃, but if the temperature is too high, a reaction vessel having a higher pressure is required, which is not preferable, and a range of 50 to 101 ℃ is suitable for practical use.

Further, in the case of a perovskite type compound containing strontium titanate as a main component, the temperature rising rate during the synthetic reaction has a great influence on the particle size distribution. In order to obtain a powder having a narrow particle size distribution, it is necessary that the temperature rising rate is 40 ° C. or less per hour. However, if the rate of temperature increase is too slow, the reaction takes a longer time, which is not preferable, and the rate of temperature increase per hour of 10 to 30 ° C. is suitable for practical use.

The reaction time of the perovskite type compound is
If it is 0.5 hours or more, there is no particular problem, but if the reaction time becomes too long, the amount of the perovskite compound obtained per unit time becomes small, which is not preferable, and it is practically 0.5 to 5 hours. The range is appropriate.

The strontium titanate compound of the present invention includes SrTiO ₃ . However, Sr is M
g, Ca and Ba may be partially substituted by one or more alkaline earth metal elements selected from the group consisting of, and Ti is one or more selected from the group consisting of Zr and Sn. Can be partially replaced by the elements of

In order to synthesize a strontium titanate-based perovskite-type compound in which a part of Sr is partially substituted with Mg, Ca, Ba or the like, the perovskite-type compound is synthesized in a mixed aqueous solution of Sr and the above element. Should be done. At that time, the total amount of alkaline earth metal is 0.1 to
It is necessary to adjust the concentration to 0.8 mol / liter and the molar ratio with the hydrous oxide to 0.9 to 1.2.

To synthesize a strontium titanate compound in which a part of Ti is partially substituted with Zr or Sn, or these two elements, after preparing a titania sol,
Chloride of the above element is added, and thereafter, alkali is added to the titania sol dispersion liquid, and it may be used as a raw material for synthesizing perovskite type compound as a mixture of hydrous titanium oxide and hydroxide of these elements. .

To make the obtained strontium titanate-based perovskite-type compound powder into a sintered body, 0.5-2
green at a pressure of t / cm ² to obtain a green compact, 11
50 to 1250 ° C, preferably 1150 ° C to 1200
It suffices to bake at 2 ° C for 2 to 10 hours. The obtained sintered body is
It has a sintered density of 94% or more with respect to the theoretical density and a grain diameter of 1 μm or less. That is, the strontium titanate-based perovskite-type compound powder according to the present invention can be sintered at a low temperature, and the obtained sintered body has a high sintered density and a small grain diameter.

The present invention will be described in more detail with reference to the following examples. The following examples are provided for illustration 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 filtrate reached 2200 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 4% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. N is added to the titania sol dispersion liquid.
aOH was added, the pH of the dispersion was adjusted to 6.0, and the supernatant was washed by decantation with pure water until the electric conductivity of the supernatant was 120 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase type T
Only the peak of iO ₂ is shown.

533 g (0.6 mol) of metatitanic acid having a water content of 91% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto to stand for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. Sr a _{(OH) 2 · 8H 2 O} ( purity 95.5%) 183.6g (0.66 mol) was added,
Distilled water was added to 0.3 mol / liter (SrTi
O ₃ basis) was adjusted to a slurry of SrO / TiO ₂ molar ratio 1.10. The slurry was heated to a boiling temperature (101 ° C.) at 26 ° C./H in a nitrogen atmosphere and reacted at the boiling point for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant liquid was removed under a nitrogen atmosphere, 2.5 liters of pure water was added and decantation was repeated twice for washing, and then filtration with a Nutsche. It was The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.25% by weight,
_{The 3} content was 0.10% by weight. In addition, the average particle size calculated on a weight basis using an electron micrograph is 0.05μ.
The value obtained by dividing the m / quarter deviation by the average particle diameter was 0.16. The Na content of the powder was 6 ppm. The SrO / TiO ₂ molar ratio of the powder was 1.08.

Example 2 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the filtrate reached 2200 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radical adsorbed by adding H was set to SO ₃ and 0.3
It was washed until it reached 0% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. N is added to the titania sol dispersion liquid.
aOH was added, the pH of the dispersion was adjusted to 6.0, and the supernatant was washed by decantation with pure water until the electric conductivity of the supernatant reached 180 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase type T
Only the peak of iO ₂ is shown.

160 g (0.2 mol) of metatitanic acid having a water content of 90% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. _{Sr (OH) 2 · 8H 2} O (purity 95.5%) 58.4 g (0.21 mol) was added, 0.1 mol / liter was further added distilled water (SrTiO
₍ Converted to ₃ ), and adjusted to a slurry having a SrO / TiO ₂ molar ratio of 1.05. The slurry is heated to 70 ° C in a nitrogen atmosphere at 1
The temperature was raised at 2 ° C / H and the reaction was carried out at 70 ° C for 1 hour. After the reaction, the mixture was cooled to 40 ° C., the supernatant was removed under a nitrogen atmosphere, 2.5 liters of pure water was added, and decantation was repeated twice for washing.
Filtration was performed with a Nutsche. The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.23% by weight and the SO ₃ content was 0.
It was 13% by weight. Further, the average particle diameter calculated on a weight basis using an electron micrograph was 0.20 μm, and the value obtained by dividing the quartile deviation by the average particle diameter was 0.12. Sr of the powder
The O / TiO ₂ molar ratio was 1.03.

Example 3 Hydrous titanium oxide obtained by hydrolyzing an aqueous titanium tetrachloride solution by adding aqueous ammonia was washed with pure water, and the hydrous titanium oxide slurry was mixed with SO _{3 with} respect to TiO ₂ .
As a result, 0.24% by weight of sulfuric acid was added. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. NaOH was added to the titania sol dispersion liquid, the dispersion liquid was adjusted to pH 6.0, and the supernatant liquid was washed by decantation with pure water until the electric conductivity of the supernatant liquid became 80 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, only a peak of anatase type TiO ₂ was shown.

399 g (0.6 mol) of metatitanic acid having a water content of 88% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. 166.9 g (0.6 mol) of Sr (OH) ₂ .8H ₂ O (purity 95.5%) was added, and distilled water was further added to add 0.3 mol / liter (SrTiO 3
₃ conversion), and the slurry was adjusted to a SrO / TiO ₂ molar ratio of 1.00. The slurry is heated to 70 ° C in a nitrogen atmosphere at 2
The temperature was raised at 4 ° C / H and the reaction was carried out at 70 ° C for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant was removed under a nitrogen atmosphere, 2.5 liters of pure water was added, and decantation was repeated twice for washing.
Filtration was performed with a Nutsche. The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.25% by weight, and the SO ₃ content was 0.
It was 10% by weight. In addition, the average particle diameter calculated on a weight basis using an electron micrograph was 0.08 μm, and the value obtained by dividing the quartile deviation by the average particle diameter was 0.14. Sr of the powder
The O / TiO ₂ molar ratio was 0.99.

Example 4 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the filtrate became 1300 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 5% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. N is added to the titania sol dispersion liquid.
aOH was added, the pH of the dispersion was adjusted to 6.0, and the supernatant was washed by decantation with pure water until the electric conductivity of the supernatant was 120 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase type T
Only the peak of iO ₂ is shown.

599 g (0.6 mol) of metatitanic acid having a water content of 92% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the gas in the reaction vessel with nitrogen gas. _{Sr (OH) 2 · 8H 2} O ( purity 95.5%) 165.2g (0.594 moles) of Mg
(OH) ₂ (purity 99%) 3.9 g (0.066 mol)
And then distilled water to add 0.3 mol / liter (Sr _0.9 Mg _0.1 TiO ₃ conversion), (SrO + MgO)
A slurry having a molar ratio of / TiO _{2 of} 1.20 was prepared. Heating the slurry to a boiling point at 28 ° C./H in a nitrogen atmosphere,
The reaction was carried out at the boiling point for 3 hours. After reaction, cool to 40 ° C,
The operation of removing the supernatant in a nitrogen atmosphere, adding 2.5 liters of pure water and performing decantation was repeated twice to perform washing, and then filtration was performed using a Nutsche. The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was found that the peak was shifted to a higher angle side than the peak position of strontium titanate. The C content of the powder was 0.
It was 23% by weight and the SO ₃ content was 0.11% by weight. The average particle size calculated by weight using an electron micrograph was 0.22 μm, and the value obtained by dividing the quartile deviation by the average particle size was 0.13. (SrO + MgO) of the powder
The / TiO ₂ molar ratio was 1.01.

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 filtrate reached 1300 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 5% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. N is added to the titania sol dispersion liquid.
aOH was added, the pH of the dispersion was adjusted to 6.0, and the supernatant was washed by decantation with pure water until the electric conductivity of the supernatant was 120 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase type T
Only the peak of iO ₂ is shown.

685 g (0.6 mol) of metatitanic acid having a water content of 93% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. _{Sr (OH) 2 · 8H 2} O ( purity 95.5%) 160.2 g (0.576 mol) and Ba
_{(OH) 2 · 8H 2 O} ( purity 98.5%) 46.2g
(0.144 mol) was added, and distilled water was further added to give a 0.1.
3 mol / liter (Sr _{0. 8} Ba _0.2 TiO ₃ basis),
The slurry was adjusted to a (SrO + BaO) / TiO ₂ molar ratio of 1.20. Up to boiling point of the slurry in a nitrogen atmosphere 2
The temperature was raised at 8 ° C / H and the reaction was carried out at the boiling point for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant liquid was removed under a nitrogen atmosphere, 2.5 liters of pure water was added and decantation was repeated twice for washing, and then filtration with a Nutsche. It was The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was found that the peak was shifted to a lower angle side than the peak position of strontium titanate. The C content of the powder was 0.10% by weight and the SO ₃ content was 0.09% by weight. Further, the average particle diameter calculated on a weight basis using an electron micrograph was 0.14 μm, and the value obtained by dividing the quartile deviation by the average particle diameter was 0.11. The (SrO + BaO) / TiO ₂ molar ratio of the powder was 0.99.

Example 6 The hydrous titanium oxide obtained by hydrolyzing an aqueous titanyl sulfate solution was washed with pure water until the electric conductivity of the filtrate reached 1300 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 5% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. T is added to the titania sol dispersion liquid.
20 mol% zirconium oxychloride based on iO ₂ was added, and then NaOH was added to adjust the pH of the dispersion to 6.
It was washed by decantation with pure water until the electric conductivity of the supernatant was set to 0 and reached 160 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, only a peak of anatase type TiO ₂ was shown.

1330 g (0.6 mol) of the hydrous oxide having a water content of 96% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the gas in the reaction vessel with nitrogen gas. . Sr a _{(OH) 2 · 8H 2 O} ( purity 95.5%) 183.6g (0.66 mol) was added,
Distilled water was added to 0.3 mol / liter (SrTi
_0.8 Zr _0.2 O ₃ conversion), SrO / (TiO ₂ + ZrO ₂ )
The slurry was adjusted to a molar ratio of 1.10. In a nitrogen atmosphere, the slurry was heated to the boiling point at 30 ° C./H and reacted at the boiling point for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant liquid was removed under a nitrogen atmosphere, 2.5 liters of pure water was added and decantation was repeated twice for washing, and then filtration with a Nutsche. It was The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was found that the peak was shifted to a lower angle side than the peak position of strontium titanate. C content of the powder is 0.23% by weight
And the SO ₃ content was 0.11% by weight. Further, the average particle diameter calculated on a weight basis using an electron micrograph was 0.15 μm, and the value obtained by dividing the quartile deviation by the average particle diameter was 0.11. The powder of SrO / (TiO ₂ + Zr
The O ₂ ) molar ratio was 1.02.

Comparative 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 filtrate reached 2200 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 7% by weight. When the obtained hydrous titanium oxide was examined by X-ray diffraction, only a peak of anatase type TiO ₂ was shown.

533 g (0.6 mol) of metatitanic acid having a water content of 91% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto to stand for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. Sr a _{(OH) 2 · 8H 2 O} ( purity 95.5%) 183.6g (0.66 mol) was added,
Distilled water was added to 0.3 mol / liter (SrTi
O ₃ basis) was adjusted to a slurry of SrO / TiO ₂ molar ratio 1.10. The slurry was heated to a boiling temperature (101 ° C.) at 24 ° C./H in a nitrogen atmosphere and reacted at the boiling point for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant liquid was removed under a nitrogen atmosphere, 2.5 liters of pure water was added and decantation was repeated twice for washing, and then filtration with a Nutsche. It was The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.24% by weight,
_{The 3} content was 0.12% by weight. In addition, the average particle size calculated on a weight basis using an electron micrograph is 0.05μ.
The value obtained by dividing the m / quarter deviation by the average particle diameter was 0.34. The SrO / TiO ₂ molar ratio of the powder was 1.09.

Comparative Example 2 The hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the electric conductivity of the filtrate reached 2100 μS / cm. NaO was added to the hydrous titanium oxide slurry.
Sulfuric acid radicals adsorbed by adding H are set to SO ₃ and 0.2
Washed to 4% by weight. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH of the slurry to 1.0 to obtain a titania sol dispersion liquid. N is added to the titania sol dispersion liquid.
AOH was added, the pH of the dispersion was adjusted to 6.0, and the supernatant was washed by decantation with pure water until the electric conductivity reached 140 μS / cm. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase type T
Only the peak of iO ₂ is shown.

533 g (0.6 mol) of metatitanic acid having a water content of 91% thus obtained was placed in a reaction vessel made of SUS, and nitrogen gas was blown thereinto and left for 20 minutes to replace the inside of the reaction vessel with nitrogen gas. Sr a _{(OH) 2 · 8H 2 O} ( purity 95.5%) 183.6g (0.66 mol) was added,
Distilled water was added to 0.3 mol / liter (SrTi
O ₃ basis) was adjusted to a slurry of SrO / TiO ₂ molar ratio 1.10. The slurry was heated to a boiling temperature (101 ° C.) at 76 ° C./H in a nitrogen atmosphere and reacted at the boiling point for 3 hours. After the reaction, the mixture was cooled to 40 ° C., the supernatant liquid was removed under a nitrogen atmosphere, 2.5 liters of pure water was added and decantation was repeated twice for washing, and then filtration with a Nutsche. It was The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.28% by weight,
_{The 3} content was 0.10% by weight. The average particle size calculated on a weight basis using an electron micrograph is 0.04μ.
The value obtained by dividing the m / quarter deviation by the average particle diameter was 0.24. The SrO / TiO ₂ molar ratio of the powder was 1.03.

Comparative Example 3 Titanium oxide hydroxide obtained by hydrolysis by adding aqueous ammonia to titanium tetrachloride aqueous solution was decanted with pure water until the electric conductivity of the supernatant was 70 μS / cm. Washed. When the obtained hydrous titanium oxide was examined by X-ray diffraction, anatase-type TiO ₂
Only the peak of is shown.

240 g (0.3 mol) of metatitanic acid having a water content of 90% thus obtained and 0.5 liter of pure water were placed in a reaction vessel made of SUS, and nitrogen gas was blown into the reaction vessel.
After leaving for 5 hours, the inside of the reaction vessel was replaced with nitrogen gas. Sr (O
H) ₂ · 8H ₂ O (purity 95.5%) 169.8g (0.
(495 mol) in 1 liter of water at 90 ° C, and after boiling, it is filtered to remove strontium carbonate, and the reaction in which metatitanic acid is added while paying close attention to the filtrate in a nitrogen gas atmosphere so that it does not come into contact with air Place in a container and add distilled water to obtain 0.15 mol / liter (SrTiO 3
₃ conversion), and the slurry was adjusted to a SrO / TiO ₂ molar ratio of 1.65. The boiling point of the slurry in a nitrogen atmosphere is 10 ° C.
The temperature was raised at / H and the reaction was carried out at the boiling point for 8 hours. 40 after reaction
The mixture was cooled to 0 ° C., the supernatant was removed under a nitrogen atmosphere, 2.5 l of pure water was added and decantation was repeated twice for washing, and then filtration was carried out using a Nutsche. The obtained cake was dried in the atmosphere at 110 ° C. for 4 hours. When the obtained powder was examined by X-ray diffraction, it was a single phase of strontium titanate. Also, no particles other than strontium titanate were observed by observation with an electron microscope. The C content of the powder was 0.25% by weight, and the SO ₃ content was 0.01% by weight or less. In addition, the average particle diameter calculated on a weight basis using an electron micrograph was 0.15 μm, and the value obtained by dividing the quartile deviation by the average particle diameter was 0.14. SrO of the powder
The / TiO ₂ molar ratio was 1.11. The obtained powder is molded under a pressure of 1 t / cm ² to obtain a green compact, 1
A sintered body was produced by firing at 150 ° C. for 2 hours. The sintered density of the sintered body was measured by the Archimedes method, the polished surface of the sintered body was subjected to thermal etching, and then the grain size was measured by a scanning electron microscope. The sintered density was 4.33 g. / Cm ³ , and the grain diameter was 2.5 μm.

The powders obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were compacted at a pressure of 1 t / cm ² to obtain green compacts, which were sintered at 1150 ° C. for 2 hours to prepare sintered compacts.
The sintered density of the sintered body was measured by the Archimedes method, the polished surface of the sintered body was further subjected to thermal etching, and then the grain size was measured by a scanning electron microscope. The results are shown in Table 1.

[0054]

[Table 1] As shown in the above examples, the strontium titanate-based perovskite-type compound fine particle powder obtained by the present invention can be sintered at a low temperature, and the obtained sintered body has a high sintered density and small grains. Have a diameter.

Claims (6)

[Claims] 1. An average particle size of 0.03 to 0.3 μm, a value obtained by dividing a quartile deviation by the average particle size is 0.2 or less, and contains SO ₃ of 0.04 to 0.14% by weight. A strontium titanate-based perovskite-type compound fine particle powder characterized by the above. 2. The strontium titanate-based perovskite-type compound fine particle powder according to claim 1, wherein Sr is partially substituted with one or more elements selected from the group consisting of Mg, Ca and Ba. 3. The strontium titanate-based perovskite-type compound fine particle powder according to claim 1, wherein Ti is partially substituted with one or more elements selected from the group consisting of Zr and Sn. 4. A dispersion of titania sol obtained by adding hydrochloric acid or nitric acid to a hydrous titanium oxide slurry to adjust the pH of the slurry to 1.5 or less, and then adding an alkali to wash the dispersion. Sr hydroxide is added to the hydrous oxide to adjust Sr 0.1 to 0.8 mol / liter and the mixing ratio of Sr and hydrous oxide to a molar ratio of 0.9 to 1.2. The slurry is heated to a reaction temperature of 50 ° C. or higher at a heating rate of 40 ° C. or less per hour to 0.5
The method for producing a strontium titanate-based perovskite-type compound fine particle powder according to claim 1, which is synthesized by holding for 5 hours. 5. A sintered body of a strontium titanate-based perovskite compound having a sintered density of 94% or more of the theoretical density and a grain diameter of 1 μm or less. 6. The strontium titanate-based perovskite compound according to claim 1 is added to 0.5.
Molded at a pressure of ~ 2t / cm ² into a green molded body,
The method for producing a sintered body according to claim 5, wherein the firing is performed at 1150 to 1250 ° C for 2 to 10 hours.