JP2999821B2 - Method for producing fine powder of perovskite compound - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a fine perovskite compound powder used as a raw material for ceramics.

BACKGROUND ART In recent years, as electronic devices have become smaller, lighter, and more sophisticated, perovskite-type ceramics used in capacitors, thermistors, and the like have also been required to be thinner and smaller. In terms of technology such as sintering, thinning and miniaturization have been studied.

However, the perovskite-type compound used as the raw material is obtained by a solid-phase reaction,
Regardless of the average particle size of 0.8 μm or more, no matter how much the technology at the time of ceramicization is used, the ceramics obtained are
There is a limit to the miniaturization and thinning that can be achieved, and it has not been possible to achieve its purpose sufficiently.

That is, the conventionally used perovskite compound is M
g, at least one carbonate or oxide selected from metal elements such as Ca, Sr, Ba, and Pb (hereinafter, referred to as group A elements) and metal elements such as Ti, Zn, Hf, and Sn (hereinafter, referred to as B It is manufactured by mixing at least one oxide selected from the group elements), heat-treating it at a high temperature of 1000 ° C or higher to form a perovskite-type compound, and then mechanically pulverizing it with a ball mill or the like. For this reason, an average particle diameter of only 0.8 μm or more can be obtained. Therefore, as described above, there has been a problem that ceramics molded using the raw material cannot be sufficiently reduced in size and thickness. .

In order to solve such a problem, Japanese Patent Laid-Open No.
39726 JP, JP-A-61-91016, JP-A-60-9082
No. 5, JP-A-61-31345, etc., have proposed a method for producing a fine-particle perovskite compound having an average particle diameter of 0.2 μm or less by a wet method.

However, in the wet method, although fine perovskite-type compounds can be obtained, the obtained perovskite-type compounds are not sufficiently reacted compared to the perovskite-type compounds obtained by the solid-phase reaction, and the crystals are not crystallized. In terms of structure, there is a drawback that it contains a large amount of structural water and only those having poor crystallinity can be obtained.

Therefore, the fine-particle perovskite compound obtained by the wet method is baked at a temperature at which grain growth does not occur, and when used as a thin film ceramic material, when dispersed in an aqueous system and blended with a binder, the water-soluble component is reduced. In the molding and drying process, the resulting ceramic is
There is a disadvantage that the composition becomes non-uniform and the physical and electrical characteristics vary widely.

It is also possible to disperse and mix the particulate perovskite type compound obtained by the above wet method in an oil system, but the reaction progress rate of the perovskite type compound is low, and the crystallinity is insufficient. The ceramics have variations in physical characteristics and electrical characteristics as in the case of the aqueous dispersion.

In order to solve the above-mentioned drawbacks, it is possible to raise the baking temperature to allow the reaction to proceed sufficiently and to improve the crystallinity. However, when the baking temperature is increased, the particles grow, and the characteristics as fine particles are obtained. Is lost, and it becomes the same as the perovskite-type compound obtained by the solid-phase reaction, so that the ceramics cannot be sufficiently reduced in thickness and size.

In addition, when a perovskite compound having a large average particle size obtained by a solid-phase reaction is micronized by mechanical pulverization, it is inevitable to mix impurities from the pulverization medium, and the contaminants cannot be separated. Therefore, there is a problem that it becomes an obstacle when forming the ceramic thin film.

Among the perovskite compounds, barium titanate is particularly often used as a raw material for ceramics. Barium titanate obtained by the solid phase reaction is tetragonal, and that obtained by the wet method is cubic. In order to obtain a high-performance ceramic thin film, it is preferable to use tetragonal barium titanate that can achieve densification and that has a small average particle size. However, according to the wet method, barium titanate having a small average particle size is obtained, which has the above-mentioned disadvantages.On the other hand, barium titanate obtained by a solid-phase reaction is a tetragonal crystal. It has the disadvantage that the average particle size is large and it has to be ground. Moreover, the barium titanate obtained by pulverization has a wide particle size distribution width, and cannot have a uniform particle size.

As described above, the perovskite compound in the form of fine particles cannot be obtained by the solid-phase reaction, and the perovskite compound having insufficient reaction progress or insufficient crystallinity cannot be obtained by the conventional wet method, so that the characteristics are good. There was a problem that ceramics could not be obtained.

Therefore, an object of the present invention is to provide a method in which the reaction proceeds sufficiently and a fine-particle perovskite compound having good crystallinity can be easily produced.

DISCLOSURE OF THE INVENTION The present inventors have prepared a perovskite-type compound powder in excess of Group A elements by subjecting a mixed aqueous solution of a compound of Group A elements and a compound of Group B elements to a wet reaction at an A / B atomic ratio of excess of Group A elements. , A /
In comparison with the perovskite type compound powder having a B atomic ratio of about 1, the grain growth during firing occurs at a high temperature.
The perovskite-type compound powder in excess of group elements is burned at a temperature before grain growth occurs, and the obtained fired product is washed with an acid solution, washed with water, and filtered to remove excess group A elements, so that the reaction is sufficient. And found that a fine perovskite compound powder having good crystallinity can be easily obtained,
The present invention has been completed.

The present invention relates to at least one compound selected from compounds of Group A elements consisting of alkaline earth metal elements such as Mg, Ca, Sr and Ba and / or divalent metal elements such as Pb;
Tetravalent metal elements such as Ti, Zr, Hf, Sn and / or Z
at least one compound selected from the group B compounds consisting of composite metal elements of divalent or trivalent metal elements such as n, Ni, Co, Mg, Fe, and Sb and pentavalent metal elements such as Nb and Sb An aqueous solution of the mixture in which the A / B atomic ratio with the A / B atom ratio is excessive is subjected to a wet reaction, and the obtained reaction product powder having the A / B atomic ratio in excess of the A group element is calcined at a temperature before particle growth occurs. The obtained calcined product was washed with an acid solution, washed with water, and filtered to remove excess A.
An object of the present invention is to provide a method for producing a fine perovskite compound powder having an average particle diameter of 0.3 μm or less, which is characterized by removing group elements.

According to another aspect of the present invention, there is provided a barium titanate tetragonal crystal having an average particle size of 0.3 μm or less.

In the present invention, examples of the compound form of the compound of the group A element and the compound of the group B element used in the above reaction include a hydroxide, an oxide, an organometallic compound, and a salt.

In the reaction between the compound of the group A element and the compound of the group B element, the compound of the group A element or the compound of the group B element may be a commercially available product as it is, or a synthesized product may be used. You may.

When a hydroxide or an oxide of a group B element is used as the compound of the group B element, the particle diameter thereof is 0.3 μm in average particle diameter.
m or less, preferably 0.1 μm or less,
If it exceeds 0.3 μm, the reaction becomes difficult.

In addition, in the reaction, it is necessary to use a compound of the group A element and a compound of the group B element which have a particle size equal to or smaller than the particle diameter of the perovskite-type compound fine powder to be obtained, except for those that dissolve during the reaction. .

In the reaction, at least one compound selected from compounds of Group A elements and at least one compound selected from compounds of Group B elements are mixed in an A / B atomic ratio in excess of Group A elements. In the present invention, the A / B atomic ratio refers to an atomic ratio between a group A element and a group B element. The above mixing may be performed by a normal mixing method.

In the present invention, as a wet reaction, a coprecipitation method, a hydrolysis method, a hydrothermal synthesis method, a normal pressure heating reaction method, or the like is employed. The coprecipitation method includes a salt of a group A element and a salt of a group B element or By reacting an alkali with the mixed solution with hydroxide, a hydrated oxide mixture or a hydroxide mixture of the group A element and the group B element is obtained, or a mixture of the salt of the group A element and the salt of the group B element is obtained. Oxic acid, citric acid and other organic acids are allowed to react dropwise,
This is a method for obtaining a water-insoluble organic acid complex salt.

The hydrolysis method is a method for obtaining a perovskite compound by adding water to an alcohol solution of a mixture of metal alkoxides and performing hydrolysis.

In the hydrothermal synthesis method, a reaction proceeds in a mixed aqueous solution of at least one compound selected from compounds of Group A elements and at least one compound selected from compounds of Group B elements.
This is a method of adjusting the pH, usually pH 10 or higher, with an alkali to obtain an aqueous alkaline mixture solution, and reacting the aqueous solution under pressure at a temperature of usually 100 to 300 ° C.

The normal pressure heating reaction method is a method in which the above-mentioned aqueous solution of the alkaline mixture is boiled under normal pressure to cause a reaction.

In the present invention, all of these wet methods can be adopted. That is, the reaction method may be selected depending on the type and purity of the perovskite compound to be obtained, and the type of the compound of the group A element and the compound of the group B element to be used.

The reaction product obtained by the wet method, that is, a perovskite-type compound, a coprecipitated hydroxide mixture, an organic acid complex salt, and the like are washed with water and filtered as necessary.
This is because, when a compound other than the perovskite-type compound component is used for performing a wet reaction, elements remaining after burning are removed. For example, when reacted in a strong alkali, it is necessary to remove Na, K, etc.
In these cases, neutralize with carbonic acid or acetic acid, wash with water,
What is necessary is just to filter.

In the present invention, drying may be performed by a usual drying method, but it is preferable that the unreacted Group A element and the reaction product used in excess are obtained as a uniform powder. As such a drying method, for example, spray drying can be adopted, or an unreacted group A element is insolubilized with a carbonate ion, an oxalate ion and the like, and then subjected to ordinary filtration,
Drying may be performed.

The reaction product powder having an A / B atomic ratio in excess of the group A element obtained as described above is fired at a temperature before particle growth occurs. Here, the firing of the reaction product powder in which the A / B atomic ratio in the present invention is excessive in the group A element is described in detail as follows.

The reaction product obtained by the wet method, if the reaction product is a perovskite type compound, slightly varies depending on the type, but usually the average particle size is 0.3 μm or less, most of 0.05
~ 0.15 μm powder. When the reaction product is a coprecipitated hydroxide mixture or an organic acid complex salt, when heat-treated at 500 to 900 ° C., the average particle size is 0.3 μm or less, and most is 0.05 to 0.15.
A μm perovskite compound powder is obtained. These reaction products are usually baked for the purpose of removing adhering water and structural water, improving the crystallinity, and accelerating the reaction of unreacted components.

The higher the baking temperature, the more the above-mentioned object is achieved, but on the other hand, the growth of particles occurs. As such, they are usually fired at a temperature before particle growth occurs.
The temperature at which particle growth occurs depends on the type of perovskite compound, but in the case of the same perovskite compound, it varies depending on the A / B atomic ratio. When the atomic ratio is 1, the temperature at which particle growth occurs is 100 to 300 ° C. higher. Therefore,
In the present invention, baking can be performed at a higher temperature than the conventional A / B atomic ratio of 1, usually lower than the temperature at which grain growth occurs, and lower than the temperature at which grain growth occurs when A / B = 1.0. Fired at high temperatures. Preferably, (particle growth occurrence temperature −20 ° C.) or less, particularly (particle growth occurrence temperature −50 ° C.)
(° C.) or lower, and is baked at a temperature equal to or higher than (particle growth occurrence temperature-300 ° C.), especially above (particle growth occurrence temperature-200 ° C.).

In the present invention, the A / B atomic ratio is one in which the group A element is excessive, the A / B atomic ratio is in a range of 1.01 to 1.40, preferably 1.01 to 1.40.
It is in the range of 1.10. That is, although it differs depending on the type of the perovskite type compound, when the A / B atomic ratio is smaller than 1.01, the effect of increasing the temperature at which particle growth occurs is small, and when the A / B atomic ratio exceeds 1.40, The generation of crystalline compounds other than the perovskite-type compound occurs,
In addition, it is uneconomical in consideration of removing excess of group A element by acid treatment in the subsequent step.

The relationship between the A / B atomic ratio and the temperature at which the particle growth occurs will be specifically described using a pseudo cubic barium titanate having an average particle diameter of 0.1 μm produced by a wet method as an example. No crystal growth occurs up to 800 ° C., and the X-ray diffraction shifts to a pseudo-cubic crystal in which the lattice constant shrinks due to detachment of the structural water. Then, when baked at 900 ° C. or more, grain growth is observed, and when baked at 1000 ° C., it becomes tetragonal barium titanate having an average particle size of 0.5 μm or more.
On the other hand, if the Ba / Ti atomic ratio is Ba excess,
Upon firing at 0 ° C., tetragonal barium titanate is obtained with a grain growth of 0.1 to 0.2 μm. In the present invention, it is required that the reaction product powder in excess of the group A element be fired at a temperature before the growth of the particles. It means the temperature before growth of particles larger than 0.3 μm in diameter occurs.

In order to make the A / B atomic ratio of the reaction product be in the range of 1.01 to 1.40, the A / B atomic ratio before the reaction is set to an A / B atomic ratio even in a mixture aqueous solution containing an excess of Group A elements. 1.01 to 1.40
It is necessary to adjust.

After baking, the obtained baking product is washed with an acid solution, washed with water,
Filter to remove excess Group A elements. Any acid can be used as long as it is a water-soluble acid. For example, organic acids such as acetic acid and inorganic acids such as hydrochloric acid, nitric acid and hydrofluoric acid can be used. However, those that precipitate as salts cannot be used.

Washing of the baked goods with an acid solution may be performed by a usual method. For example, a method of slurrying the baked goods, heating if necessary, dropping an acid therein, and adjusting the pH can be adopted. The adjustment range of the pH slightly varies depending on the type of the perovskite compound and the acid used, but is usually in the range of pH 5 to 10. In addition, when the excess of the Group A element in the baked product is large, it is effective to first reduce the pH to about 10 with a strong acid such as hydrochloric acid and then adjust the pH to a desired pH with a weak acid such as acetic acid.

After washing with an acid solution, decantation may be repeated by a conventional method, followed by washing with Nutsche or the like, filtration, and drying. Water washing and filtration after this acid washing are not necessarily required to be performed in the order of water washing and filtration, and filtration may be performed prior to water washing, or water washing and filtration may be repeated. .

Veroskite compound fine powder having an average particle diameter of 0.3 μm or less obtained by the present invention (although the average particle diameter varies slightly depending on the type of the
m), compared with the fine powder of a conventional bevelovskite-type compound obtained by a wet method, the reaction has progressed sufficiently, the number of unreacted substances is small, and the crystallinity is good and the degree of crystallinity is high. In addition, the present invention enables the molding of ceramics having good physical properties and electrical properties, and having little variation among them and having stable quality. In particular, when molding a thin film ceramic, the effect is remarkably exhibited.

In particular, barium titanate obtained by the method of the present invention has an average particle size of 0.3 μm or less, preferably 0.05 to 0.25
It is a tetragonal crystal particle having a very narrow particle size distribution width and a uniform particle size within the range of μm, and thus is extremely useful as a ceramic material. That is, the tetragonal barium titanate has a denser crystal than the cubic one,
In addition, it has the advantage that high-performance ceramics are easily obtained because they are chemically stable and do not easily react with other components. Further, since the particle diameter is small and uniform, it is suitable for forming a ceramic thin film, and for example, a thin and high-capacity capacitor can be obtained.

The particle size distribution curve of barium titanate obtained by the method of the present invention is extremely sharp, and more than 60% of the total number of particles, especially more than 70%, exists within the range of ± 0.05 μm of the average particle size. Moreover, there are very few particles having a particle size of 0.3 μm or more, and when the average particle size is 0.25 μm or less,
When the total number of particles is 5% or less and the average particle size is 0.15 μm or less, there is almost no particle having a particle size of 0.3 μm or more. For example, when the average particle size is 0.2 μm, 90% of all particles
%, Especially 95% or more, is in the range of 0.1 to 0.3 μm. Such tetragonal barium titanate having a small average particle size and a uniform particle size is a novel one that could not be obtained by any known method.

Ceramics obtained from the belovskite type compound fine powder according to the present invention has excellent electrical properties, that is,
Utilizing excellent dielectric properties, piezoelectric properties, semiconductivity, etc., it is suitably used for capacitors, radio wave filters, ignition elements, thermistors, etc. in the electronics field.

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to examples.

Example 1 An aqueous titanium tetrachloride solution (Ti =
16.5% by weight) was added to 1800 ml of distilled water with stirring.
After making the diluted titanium tetrachloride aqueous solution, 700 ml of 5% by weight aqueous ammonia (manufactured by Hayashi Junyaku Kogyo Co., Ltd., reagent grade) is added over about 1 hour to obtain a titanium oxide-containing slurry, washed with Nutsche, and filtered. This was performed to obtain a hydrous titanium oxide cake.
The content of TiO _{2 in} this hydrous titanium oxide cake determined by ICP was 11.46% by weight.

Next, 240.02 g of the above-mentioned hydrous titanium oxide cake (Ti: 0.34
Distilled water was added to 5 moles), after the TiO ₂ was adjusted to 60 g / slurry, the reaction system was blanketed with _{nitrogen, Ba (OH) 2 · 8H} 2 O
141.2 g (Ba: 0.448) of reagent (special grade reagent made by Hayashi Junyaku Kogyo Co., Ltd.)
Mol), and further distilled water is added, and 0.7 mol / (BaT
iO ₃ eq.), and adjusted to a slurry of Ba / Ti atomic ratio of 1.30. The temperature of the slurry was raised to the boiling temperature over about 1 hour, and the reaction was carried out at the boiling temperature for about 3 hours. After natural cooling to room temperature,
The decantation was repeated, washed with Nutsche and filtered. Distilled water was added to the obtained cake to obtain 0.9 mol /
Re-slurried to (BaTiO ₃ equivalent), Okawara Kakoki Co., Ltd.
It was spray-dried with a spray dryer made at an inlet temperature of 250 ° C., an outlet temperature of 120 ° C. and an atomizer rotation speed of 25,000 rpm to obtain barium titanate fine powder.

The obtained barium titanate fine powder was measured for the Ba / Ti atomic ratio by ICP and X-ray fluorescence analysis, the particle size was measured by an electron micrograph, and the crystal form was examined by X-ray diffraction. Ti
It was found to be pseudo-cubic with an atomic ratio of 1.031 and an average particle size of 0.08 μm.

The above barium titanate fine powder is placed in an electric furnace at 1000 ° C. for 3 hours.
After calcination for a period of time and natural cooling, distilled water was added to the obtained baked product to prepare a slurry of about 0.7 mol / (in terms of BaTiO ₃ ). The slurry was heated to 60 ° C., a 10% by weight aqueous acetic acid solution was added dropwise to adjust the pH to 8.0, and after maintaining for about 1 hour, washed with Nutsche, filtered and dried to obtain fine barium titanate powder. I got a body.

The obtained barium titanate fine powder was measured for the Ba / Ti atomic ratio by ICP and X-ray fluorescence analysis, and the crystal form was examined by electron micrograph and X-ray diffraction analysis. And the crystal form has the same peak position as tetragonal barium titanate (BaTiO ₃ ) produced by the wet method,
In addition, a square crystal edge was observed in an electron microscope observation, which proved to be tetragonal.

Furthermore, the average particle size and the particle size distribution were measured from the electron micrograph of the obtained barium titanate fine powder. The measurement was performed by drawing a horizontal line at regular intervals on an electron micrograph and measuring the diameter of 3000 particles on the line. Since the particle shape was a rectangular parallelepiped, the length of one side was defined as the particle diameter. The measurement results of the particle size distribution (ratio to the total number of particles) and the average particle size are shown below.

(Particle size distribution) 0.3 μm or more 4% 0.25 to 0.3 μm 11% 0.2 to 0.25 μm 36% 0.15 to 0.2 μm 34% 0.1 to 0.15 μm 12% 0.1 μm or less 3% Average particle size: 0.2 μm In the examples and the like, the means for analyzing and measuring the product is the same as that in the first embodiment.

Example 2 The same operation as in Example 1 was carried out to obtain hydrous titanium oxide-Ba
(OH) ₂ · 8H ₂ O mixed slurry 0.7 mol / (BaTiO ₃ equivalents), was prepared in Ba / Ti atomic ratio of 1.20, the slurry 500ml
With heat-resistant nickel alloy autoclave (capacity 1)
And heated at 100 ° C / hr while stirring at 500 rpm.
The reaction was performed at 0 ° C. for 2 hours.

After the reaction, it was washed with water, filtered, reslurried as in Example 1, and then spray-dried to obtain barium titanate fine powder. The obtained barium titanate fine powder has a Ba / Ti atomic ratio.
1.052, pseudo-cubic with an average particle size of 0.1 μm.

The above barium titanate fine powder is placed in an electric furnace at 1000 ° C. for 3 hours.
After baking for a time and cooling naturally, about 0.7 mol / (BaTiO ₃
The slurry was heated to 60 ° C. A 10% by weight aqueous solution of acetic acid was added dropwise to the slurry to adjust the pH to 8.0, and after maintaining for about 1 hour, washed with Nutsche, filtered, and dried to obtain barium titanate fine powder.

The obtained barium titanate fine powder has a Ba / Ti atomic ratio of 1.0.
00, which was tetragonal with an average particle size of 0.15 μm. The measurement results of the particle size distribution are shown below.

(Particle size distribution) 0.25 μm or more 5% 0.2 to 0.25 μm 11% 0.15 to 0.2 μm 33% 0.1 to 0.15 μm 41% 0.1 μm or less 10% Example 3 Titanium isopropoxide having a purity of 99.99% (manufactured by Rare Metal Co., Ltd.) 100 g was dissolved in 150 ml of isopropyl alcohol (manufactured by Hayashi Junyaku Kogyo Co., Ltd., reagent grade) and heated under reflux for 2 hours. In a nitrogen atmosphere, 45 weight kept the titanium isopropoxide solution _{80 ℃% Ba (OH) 2} · 8H 2 O
The solution was gradually dropped into 340.5 g of the aqueous solution over 1 hour and 30 minutes by a roller pump.
The a / Ti atomic ratio was adjusted to 1.4. Thereafter, the reaction was carried out in the same manner as in Example 1, washed with water, filtered, and then spray-dried to obtain barium titanate fine powder. The obtained barium titanate fine powder was a pseudo cubic crystal having a Ba / Ti atomic ratio of 1.101 and an average particle size of 0.06 μm.

The above barium titanate fine powder is baked in an electric furnace (manufactured by Motoyama Co., Ltd.) at 1100 ° C. for 3 hours, naturally cooled, and then the slurry is slurried to about 0.3 mol / (BaTiO ₃ equivalent) and heated. And kept at 60 ° C. To this slurry, an aqueous hydrochloric acid solution of IN was added dropwise to adjust the pH to 9.7, and then 10% by weight.
The pH was adjusted to 7.8 by dropwise addition of an aqueous acetic acid solution, and the mixture was maintained for about 1 hour. Then, it was washed with Nutsche, filtered, and dried to obtain barium titanate fine powder.

The obtained barium titanate fine powder has a Ba / Ti atomic ratio of 0.9.
990, a tetragonal crystal having an average particle size of 0.13 μm. The measurement results of the particle size distribution are shown below.

(Particle size distribution) 0.2 μm or more 5% 0.15 μm to 0.2 μm 30% 0.10 to 0.15 μm 35% 0.10 μm or less 10% Example 4 Barium isopropoxide having a purity of 99.99% in a nitrogen atmosphere (manufactured by Rare Metal Co., Ltd.) 75.83 g (0.297 mol)
And 92.75 g (0.326 mol) of titanium isopropoxide having a purity of 99.99% (manufactured by Rare Metal Co., Ltd.) were dissolved in 350 ml of isopropyl alcohol and heated under reflux for 2 hours. To the solution was added dropwise 65 ml of distilled water over 1 hour to hydrolyze the alcoholate, and once cooled to room temperature, water was added to adjust the slurry concentration to 0.5 mol / (in terms of BaTiO ₃ ), and the Ba / Ti atomic ratio was 1.
Adjusted to 1. Thereafter, the reaction was carried out in the same manner as in Example 1. The water washing with Nutsche and the filtration were omitted, and the mixture was spray-dried as it was to obtain a pseudo cubic barium titanate fine powder having a Ba / Ti atomic ratio of 1.102 and an average particle size of 0.05 μm. I got it.

Thereafter, in the same manner as in Example 3, baking and acid treatment are performed, and Ba / T
A fine powder of tetragonal barium titanate having an i atomic ratio of 1.000 and an average particle size of 0.10 μm was obtained. The particle size distribution is as follows.

(Particle size distribution) 0.15 μm or more 8% 0.1-0.15 μm 41% 0.05-0.1 μm 51% Example 5 Titanium tetrachloride aqueous solution (Ti =
200 g (16.5% by weight, 0.688 mol) was added to 300 ml of distilled water with stirring to obtain a dilute aqueous titanium tetrachloride solution. Then 18
5 g (0.756 mol) of barium chloride (BaCl ₂ .2H ₂ O)
The dilute titanium tetrachloride aqueous solution was gradually added to the aqueous solution while maintaining the aqueous solution at 20 ° C. Meanwhile, oxalic acid _{[(COOH) 2 · 2H 2} O] 189g (1.
5 mol) in 1000 ml of distilled water to make an aqueous solution,
Was kept warm. The mixed solution of titanium tetrachloride and barium chloride was dropped into the oxalic acid aqueous solution over 3 hours,
A white precipitate was obtained. Repeat the decantation, wash with Nutsche, filter, dry and dry BaTiO (C ₂ O ₄ ) ₂
・ 4H ₂ O composite salt powder was obtained. This was baked at 600 ° C. for 10 hours to obtain a pseudo cubic barium titanate fine powder having a Ba / Ti atomic ratio of 1.05 and an average particle size of 0.2 μm.

Thereafter, in the same manner as in Example 2, baking and acid treatment are performed, and Ba / T
A fine powder of tetragonal barium titanate having an i atomic ratio of 1.001 and an average particle size of 0.22 μm was obtained. The particle size distribution is as follows.

(Particle size distribution) 0.3 μm or more 3% 0.25 μm to 0.3 μm 33% 0.2 to 0.25 μm 34% 0.15 to 0.2 μm 30% Example 6 Hydrous titanium oxide cake obtained in the same manner as in Example 1 (1
1.46% by weight) Add distilled water to 200g and slurry concentration 60g /
Was adjusted. The reaction system was blanketed with nitrogen, the slurry _{Sr (OH) 2 · 8H 2} O ( HayashiJunyaku Kogyo Co., reagent special grade) added 107.1 g, was mixed. Final slurry concentration of 0.5
The amount of water was adjusted to mol / (SrTiO ₃ conversion).
The reaction is carried out in the same manner as above, after the reaction, washed with Nutsche, filtered, spray-dried and Sr / Ti atomic ratio 1.07, average particle size 0.06 μm
Quasi-cubic strontium titanate fine powder was obtained.

The above strontium titanate fine powder was baked at 1150 ° C. for 3 hours, adjusted to pH 7.6 in the same manner as in Example 1, then acid-treated, washed with water, filtered and dried to obtain a Sr / Ti atomic ratio of 0.998 and an average particle size of 0.998. A cubic strontium titanate fine powder having a diameter of 0.1 μm was obtained.

Example 7 Hydrous titanium oxide cake obtained in the same manner as in Example 1 (1
Distilled water was added to 200 g of 1.46% by weight (0.286 mol) to adjust the slurry concentration to 60 g /. The reaction system was blanketed with nitrogen, the above slurry _{Ba (OH) 2 · 8H 2} O ( HayashiJunyaku Kogyo Co., reagent grade) 79.0 g (0.25 mol) and Sr (OH) ₂
· 8H ₂ O (HayashiJunyaku Kogyo Co., reagent grade) was added 27.4 g (0.1 mol).

Thereafter, the reaction was carried out in the same manner as in Example 1. After the reaction, the reaction product was washed with water by Nutsche, filtered, and spray-dried to obtain a Ba / Ti atomic ratio of 0.780.
A pseudo-cubic barium strontium titanate-strontium compound fine powder having an Sr / Ti atomic ratio of 0.314 and an (Ba + Sr) / Ti atomic ratio of 1.094 and an average particle diameter of 0.05 μm was obtained.

The barium strontium titanate compound fine powder was baked at 1050 ° C. for 3 hours, adjusted to pH 8.0 in the same manner as in Example 1, then acid-treated, washed with water, filtered, and dried to obtain a Ba / Ti atomic ratio of 0.7031, Sr / Ti atomic ratio 2.998, (Ba + Sr) / Ti atomic ratio 1.0
029, cubic barium titanate having an average particle size of 0.08 μm
A strontium compound fine powder was obtained.

Pure water Example _{8 2, ZrOCl 2 · 8H 2} O ( HayashiJunyaku Industry Co.,
129 g (0.4 mol) manufactured by Osaka Titanium Co., Ltd. (Ti = 16.5% by weight) was added and dissolved in the solution. .

To the above aqueous solution, 5% by weight aqueous ammonia (manufactured by Hayashi Junyaku Kogyo Co., Ltd., reagent grade) was added over about 1 hour, the slurry was adjusted to pH 7.5, and a hydrous titanium zirconium coprecipitate was obtained. After washing with Nutsche and filtration, a hydrous titanium zirconium cake was obtained. The hydrous titanium oxide, zirconium cake was subjected to TiO _2, ZrO ₂ of quantified by ICP, TiO ₂ 10 wt% and a ZrO ₂ 3.9% by weight.

Next, the above-mentioned hydrous titanium oxide zirconium cake 250g
(Ti: 0.313 mol, Zr: 0.079 mol) and distilled water
Mol / (TiO ₂ + ZrO ₂ conversion) after adjusting the slurry, the reaction system was blanketed with _{nitrogen, Ba (OH) 2 · 8H} 2 O ( HayashiJunyaku Kogyo Co., reagent special grade) 173 g (Ba: 0.55 mole ) And add Ba /
The reaction conditions were such that the (Ti + Zr) atomic ratio was 1.40.

Raise the slurry to the boiling temperature over about 1 hour,
After reacting for about 3 hours at boiling temperature, cool naturally to room temperature, repeat decantation, wash with Nutsche,
Filtration was performed. Distilled water was added to the obtained cake to reslurry to 0.7 mol / [Ba (Ti _0.8 Zr _0.2 ) O ₃ conversion]
The slurry was adjusted to pH 9.0 with acetic acid, stirred for about 1 hour, washed with Nutsche, and filtered.

This was further added with distilled water to give 0.9 mol / [Ba (Ti _0.8
Zr _0.2 ) 03 conversion], and using an Okawara Kakoki Co., Ltd. spray dryer, inlet temperature 250 ° C,
Spray drying is performed at an outlet temperature of 120 ° C and an atomizer rotation speed of 25000 rpm, and a Ba / Ti atomic ratio of 1.333, a Ba / Zr atomic ratio of 5.556, and Ba / (T
(i + Zr) A pseudo-cubic titanium / barium zirconate compound fine powder having an atomic ratio of 1.075 and an average particle size of 0.07 μm was obtained.

Thereafter, the same treatment as in Example ₁ was carried out except for baking at 1200 ° C., and the Ba / Ti atomic ratio was 1.245, the Ba / Zr atomic ratio was 5.025, and the Ba / (Ti + Z
r) Cubic titanium with an atomic ratio of 0.9980 and an average particle size of 0.2 μm
A barium zirconate compound fine powder was obtained.

Example 9 While keeping a 0.1N HCl acidic solution at 0 ° C. and stirring, 135.5 g of SnCl 4 (reagent grade, manufactured by Hayashi Junyaku Co., Ltd.) was added thereto.
Was added and dissolved to make a SnCl ₄ aqueous solution. In the aqueous solution,
Titanium tetrachloride aqueous solution (Ti: 16.
557.4 g) were dissolved and mixed.

5 wt% ammonia water was added to the above mixed aqueous solution to adjust the pH to 7.
After neutralizing and adjusting to 51, aging for 30 minutes, obtaining a precipitate of tin / titanium hydrated oxide, washing with Nutsche, filtering,
A tin / titanium hydrate cake was obtained.

Distilled water was added to 500 g of the above-mentioned tin / titanium hydrated oxide cake to make the total amount thereof 1 and slurried.
When the concentration of Sn was measured, Ti: 0.425 mol /, Sn:
0.106 mol /.

After the reaction system was set to a nitrogen atmosphere, Ba (O
H) ₂ · 8H ₂ O (HayashiJunyaku Kogyo Co., reagent special grade) 201g was added, was adjusted to Ba / (Ti + Sn) atomic ratio of 1.2, thereafter, the reaction was carried out in the same manner as in Example 1, washed with water , Filtration and spray drying to obtain a Ba / Ti atomic ratio of 1.299, a Ba / Sn atomic ratio of 5.263, and Ba / (Ti + S
n) Pseudo cubic titanium / barium stannate compound fine powder having an atomic ratio of 1.0417 and an average particle size of 0.09 μm was obtained.

The above titanium / barium stannate compound fine powder is 1100 ° C
And baked for 3 hours, adjusted to pH 8.2 in the same manner as in Example 1, subjected to an acid treatment, washed with water, filtered, and dried to obtain a Ba / Ti atomic ratio of 1.253, a Ba / Sn atomic ratio of 5.025, and a Ba / Sn atomic ratio of 5.025. / (Ti + Sn) atomic ratio 1.
In 003, a cubic titanium / barium stannate compound fine powder having an average particle size of 0.11 μm was obtained.

Example 10 Hydrous titanium oxide cake 240 obtained in the same manner as in Example 1.
2 g (Ti: 0.345 mole) of distilled water was added, after TiO ₂ was adjusted to 50 g / slurry, the reaction system was blanketed with nitrogen, Ba / Ti
Atomic ratio 0.95, Ca / Ti atomic ratio 0.15, (Ba + Ca) / Ti atomic ratio 1.
So that 05 was added _{Ba (OH) 2 · 8H 2} O and CaCl _2.

After NaOH was added to the slurry to adjust the pH of the slurry to 14, a reaction was carried out in the same manner as in Example 1.

After maintaining the above reaction product slurry at 60 ° C., carbon dioxide gas was blown into the slurry to adjust the pH to 6 or less, followed by washing with water, decantation, and filtration. The obtained cake was spray-dried under the same conditions as in Example 1 to obtain a barium / calcium titanate compound fine powder. The obtained barium calcium titanate compound fine powder has a Ba / Ti atomic ratio of 0.941 and a Ca / Ti atomic ratio of 0.1.
02. A pseudo-cubic crystal having an atomic ratio of (Ba + Ca) / Ti atomic ratio of 1.043 and an average particle size of 0.07 μm.

The barium / calcium titanate compound fine powder was baked and acid-treated in the same manner as in Example 1 to obtain a Ba / Ti atomic ratio.
0.902, atomic ratio of Ca / Ti 0.101, atomic ratio of (Ba + Ca) / Ti 1.003
Thus, a barium / calcium titanate compound fine powder having an average particle size of 0.1 μm was obtained.

Example 11 Hydrous titanium oxide cake 240 obtained in the same manner as in Example 1.
2 g (Ti: 0.345 mole) of distilled water was added, after TiO ₂ was adjusted to 50 g / slurry, the reaction system was blanketed with nitrogen, Ba / Ti
Atomic ratio 0.95, Mg / Ti atomic ratio 0.10, (Ba + Mg) / Ti atomic ratio 1.
Ba (OH) ₂ .8H ₂ O and MgCl ₂ .6H ₂ O were added to make 05.

Thereafter, the reaction was carried out in the same manner as in Example 10, and the Ba / Ti atomic ratio
0.93, Mg / Ti atomic ratio 0.105, (Ba + Mg) / Ti atomic ratio 1.035
And a pseudo-cubic barium titanate with an average particle size of 0.06 μm
A magnesium compound fine powder was obtained.

The barium / magnesium titanate compound fine powder was baked and acid-treated in the same manner as in Example 1 to obtain a Ba / Ti atomic ratio of 0.900 and a Mg / Ti atomic ratio of 0.101 (Ba + Mg) / Ti atomic ratio of 1.001.
Thus, a cubic barium magnesium titanate compound fine powder having an average particle size of 0.12 μm was obtained.

Example 12 An aqueous titanium tetrachloride solution (Ti: 1) manufactured by Osaka Titanium Co., Ltd.
284 g (Ti: 0.98 mol) was added to distilled water 1.2 with stirring to obtain a dilute titanium tetrachloride aqueous solution.
9.2 g of SbCl ₃ (Sb: 0.04
Mol), and dissolved and mixed.

5% by weight of the above mixed aqueous solution was added over 1 hour to adjust the pH to 7, thereby obtaining a white coprecipitate. After the white coprecipitate was washed with Nutsche and filtered, distilled water was added to the obtained cake to make a total slurry of 1.6.
When the concentrations of Ti and Sb in the slurry were measured by ICP, the Ti concentration was 0.576 mol / and the Sb concentration was 0.024 mol /.

After the reaction system was set to a nitrogen atmosphere, Ba (O
H) ₂ · 8H ₂ O was added and adjusted Ba / (Ti + Sb) atomic ratio of 1.3. Thereafter, the reaction was carried out in the same manner as in Example 1, washed with water, filtered and dried to obtain a Ba / Ti atomic ratio of 1.053 and a Ba / Sb atomic ratio of 28.5.
7. A pseudo-cubic titanium / barium antimonate compound fine powder having an atomic ratio of Ba / (Ti + Sb) of 1.015 and an average particle size of 0.07 μm was obtained.

The obtained titanium-barium antimonate compound fine powder was baked and subjected to an acid treatment in the same manner as in Example 9 to obtain Ba
A cubic titanium-barium antimonate compound fine powder having an atomic ratio of Ti / Ti of 1.020, an atomic ratio of Ba / Sb of 24.94, an atomic ratio of Ba / (Ti + Sb) of 0.980, and an average particle size of 0.13 µm was obtained.

Example 13 An aqueous solution of titanium tetrachloride (Ti: 1) manufactured by Osaka Titanium Co., Ltd.
6.5% by weight) 275.70 g (Ti: 0.95 mol) and 6.75 g (Nb: 0.025 mol) of niobium pentachloride (manufactured by Mitsui Chemicals, Inc.) and F
eCl ₃ · 6H ₂ O (HayashiJunyaku Kogyo Co., reagent special grade) 6.76 g (F
e: 0.025 mol) was dissolved and mixed in a 0.1N hydrochloric acid solution of 1.5 kept at 0 ° C. To the mixed aqueous solution was added 5% by weight aqueous ammonia over about 1 hour to adjust the pH to 7, thereby obtaining a coprecipitate. The above coprecipitate was washed with Nutsche and filtered, and distilled water was added to the cake to make the total amount 1.8, thereby forming a slurry. When the concentrations of Ti, Nb, and Fe in the slurry were measured by ICP, the concentration of Ti was 0.527 mol /, and the concentration of Nb was 0.0
The concentration of Fe was 0.0137 mol / at 138 mol /.

After the reaction system was set to a nitrogen atmosphere, Ba (O
H) ₂ · 8H ₂ O was added, 1.0235 and Ba / (Ti + Nb + Fe ) atomic ratio
After that, the reaction was carried out in the same manner as in Example 1 to obtain Ba / Ti
Atomic ratio 1.074, Ba / Nb atomic ratio 43.48, Ba / Fe atomic ratio 43.48, B
A pseudo-cubic titanium / barium niobium ferrate fine powder having an a / (Ti + Nb + Fe) atomic ratio of 1.0235 and an average particle size of 0.09 μm was obtained.

The titanium / niobium barium ferrate compound fine powder was baked and acid-treated in the same manner as in Example 2 to obtain a Ba / Ti
Atomic ratio 1.052, Ba / Nb atomic ratio 40, Ba / iron atomic ratio 40, Ba / (Ti
(+ Nb + Fe) atomic ratio of 0.994 and cubic titanium / niobium barium ferrate compound fine powder having an average particle size of 0.12 μm were obtained.

Comparative Example 1 After the reaction was carried out in the same manner as in Example 1, the obtained barium titanate cake was re-slurried to 0.6 mol /, and the pH was adjusted to 8 with acetic acid. Wash with Nutsche, filter, dry and dry to Ba / Ti atomic ratio 1.001, average particle size 0.08μm
Of cubic barium titanate fine powder was obtained.

The barium titanate fine powder was baked for 3 hours while changing the baking temperature. The relationship between the average particle size of the obtained barium titanate and the crystal system is as follows.

Baking temperature Average particle size Crystal form 800 ° C 0.09μm Pseudo cubic 900 ° C 0.14μm Pseudo cubic 1000 ° C 0.5μm tetragonal 1100 ° C 0.7μm tetragonal 1200 ° C 0.9μm tetragon In the case of obtaining fine powder having the same particle size as the barium titanate obtained in Examples 1 to 5, barium titanate by a conventional wet method in which the Ba / Ti atomic ratio is controlled to 1 is 900 ° C. It turns out that you have to bake below. Therefore, only a pseudo-cubic crystal form can be obtained.

Example 14 The tetragonal barium titanate fine powder obtained in Example 1 was mixed with 850
C. for 3 hours, and wet pulverized and dispersed by "Ultra Viscomil VVM-2L" manufactured by Igarashi Kikai Co., Ltd. Thereafter, ball milling was performed for 12 hours using a resinous ball pot.

Polyethylene glycol, butylbenzyl phthalate, nonionic octylphenoxyethanol, acrylic resin emulsion, and wax emulsion were each 3% by weight in terms of solid content based on barium titanate,
% By weight, 0.2% by weight, 8% by weight, and 0.1% by weight, and further ball-mixed for 24 hours.

The resulting slurry was degassed under vacuum while stirring to adjust the viscosity to 10,000 cps, and then formed into a thin film with a doctor blade to obtain a green sheet.

After stacking 5 of the above green sheets at 700 kg / cm ² pressure, slowly raise the temperature from 200 ° C to 500 ° C at 20 ° C / hr, degrease, and fire at 1150 ° C for 2 hours to obtain a barium titanate thin film A sintered body was obtained.

As a comparative product, barium titanate obtained in Comparative Example 1 (fired at 900 ° C.) was molded and fired in the same manner as described above.

The barium titanate of Example 1 and Comparative Example 1 used as a raw material for producing the thin film sintered body was pulverized by a ball mill for 12 hours, and the water-soluble component was subjected to ICP.
Table 1 shows the results of the analysis.

Table 2 shows the variation in the thickness of the green sheet obtained by forming the thin film.

Variation in the firing line shrinkage of the obtained sintered body (10 for each sample)
Table 3) is shown in Table 3.

The electrical characteristics (20 ° C
Table 4 shows the results obtained by measuring the dielectric constant and the dielectric loss using a LCR meter 4272A manufactured by Yokogawa Hewlett-Packard Company.

As shown in Table 1, barium titanate of Example 1
Compared with the barium titanate of Comparative Example 1 corresponding to the conventional wet method, the amount of water-soluble components was smaller, indicating that the reaction was proceeding sufficiently.

Further, as shown in Tables 2 and 3, when the barium titanate of Example 1 was used, the variation in the thickness of the green sheet and the firing line were larger than when barium titanate of Comparative Example 1 was used. Small variation in shrinkage. This indicates that the barium titanate of Example 1 had a sufficiently advanced reaction, had a uniform composition, and had better dispersion than the barium titanate of Comparative Example 1.

Further, as shown in Table 4, the sintered body using barium titanate of Example 1 had better electrical characteristics and a higher electrical property than the sintered body using barium titanate of Comparative Example 1. There is little variation. That is, the dielectric constant is large, the dielectric loss is small, and the variation is small. This is because the barium titanate of Example 1 has a more homogeneous composition than the barium titanate of Comparative Example 1, and the reaction has proceeded sufficiently.
In addition, the crystallinity is good, indicating that high-density sintering is possible.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-297214 (JP, A) US Patent 4,636,378 (US, A) European publication 141551 (EP, A1) French publication 2601352 (FR, A) (58) ) Fields investigated (Int.Cl. ⁷ , DB name) C01G 19 / 00,23 / 00,25 / 00 C01B 13/36 C01G 30/02 C01G 49/00

Claims (11)

(57) [Claims] At least one compound selected from the group A compounds consisting of alkaline earth metal elements such as Mg, Ca, Sr and Ba and / or divalent metal elements such as Pb,
Tetravalent metal elements such as Ti, Zr, Hf, Sn and / or Z
^{n, - Ni, Co, Mg} , Fe, at least one selected from compounds of divalent or trivalent metallic element and Nb, a composite metal elements consisting of group B element and pentavalent metal element such as Sb, such as Sb An aqueous solution of the mixture in which the A / B atomic ratio with the compound is excessive in the group A element is subjected to a wet reaction, and the obtained reaction product powder in which the A / B atomic ratio is excessive in the group A element is obtained at a temperature before the particle growth occurs. Baking, and the obtained baking product is washed with an acid solution, washed with water, and filtered to remove excess A
A method for producing fine perovskite compound powder having an average particle diameter of 0.3 μm or less, characterized by removing group elements. 2. The perovskite compound fine powder according to claim 1, wherein the compound of the group A element is a hydroxide and / or an oxide, and the compound of the group B element is a hydroxide and / or an oxide. Manufacturing method. 3. The method according to claim 1, wherein the compound of the group A element is a hydroxide and / or an oxide, and the compound of the group B element is an organometallic compound. 4. The group A element compound is an organometallic compound,
The method for producing a fine perovskite compound powder according to claim 1, wherein the compound of Group B element is a hydroxide and / or an oxide. 5. The compound of Group A element is an organometallic compound, and the compound of Group B element is an organometallic compound.
The method for producing the perovskite compound fine powder described above. 6. The compound of Group A element is barium hydroxide and B is
The method for producing fine perovskite compound powder according to claim 1, wherein the compound of the group element is hydrous titanium oxide, and the perovskite compound is tetragonal barium titanate. 7. The compound of Group A element is barium hydroxide and B is
The method for producing fine perovskite compound powder according to claim 1, wherein the compound of the group element is hydrous titanium oxide, and the perovskite compound is tetragonal barium titanate having an average particle size of 0.05 to 0.3 µm. 8. The method for producing fine perovskite compound powder according to claim 1, wherein the compound of the group A element is strontium hydroxide, the compound of the group B element is hydrous titanium oxide, and the perovskite compound is strontium titanate. . 9. A tetragonal barium titanate crystal having an average particle size of 0.3 μm or less. 10. The tetragonal barium titanate crystal according to claim 9, wherein the average particle size is in the range of 0.05 to 0.25 μm. 11. The ratio of particles having an average particle size in the range of 0.1 to 0.25 μm and having a particle size of 0.3 μm or more is 0 to 10.
The tetragonal barium titanate crystal according to claim 9, which is 5%.