JPH0543240A - Production of zirconium-containing perovskite compound fine powder - Google Patents

Abstract

PURPOSE:To easily obtain a zirconium-contg. perovskite compd. fine powder excellent in dispersibility, reactivity, etc. CONSTITUTION:(1) A barium compd. and/or a strontium compd. and a zirconium compd. or a zirconium compd. and a titanium compd. are mechanically crushed and allowed to react with one another on a wet basis to produce a zirconium- contg. perovskite compd. fine powder shown by the general formula ABO3 (where A is barium and/or strontium, and B is zirconium or zirconium and titanium. (2) The zirconium-contg. perovskite compd. fine powder obtained in (1) is added, and barium hydroxide and/or strontium hydroxide are allowed to react on a wet basis with the hydrolyzate of a zirconium compd. or the hydrolyzates of a zirconium compd. and a titanium compd. to produce a zirconium-contg. perovskite compd fine powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine powder of zirconium-containing perovskite compound which is preferably used as a material powder for electronic parts such as piezoelectric bodies.

[0002]

2. Description of the Related Art Conventionally, the following method has been adopted as a method for producing a zirconium-containing perovskite compound.

A solid-state reaction method in which a mixture of barium or strontium carbonate or oxide and zirconium or titanium oxide is heated at high temperature.

An oxalic acid method in which a salt of each component element is allowed to react with oxalic acid to coprecipitate as an oxalate salt and then heated at a high temperature.

A method of reacting a hydrolysis product of a zirconium compound or a titanium compound with a barium salt or a strontium salt in a strong alkaline solution such as caustic soda.

[0006]

However, since the solid-phase reaction method and the oxalic acid method described above require a step of baking at a high temperature, so-called submicron-sized fine particles having an average particle diameter of less than 1 μm can be obtained. It is difficult, and the particles have a crushed shape, resulting in poor filling properties.

In the above method of reacting in a strong alkaline solution, since the reaction of zirconium is slow, the obtained zirconium-containing perovskite compound strongly agglomerates to increase the particle size and obtain fine particles of submicron size. Was difficult.

[0008]

SUMMARY OF THE INVENTION The present inventors have proposed the general formula A
In producing a zirconium-containing perovskite compound represented by BO ₃ (wherein A is barium and / or strontium and B is zirconium or zirconium and titanium) by a wet reaction, a mechanical pulverizing means is used for the wet reaction. By incorporating
The inventors have found that a zirconium-containing perovskite compound fine powder having an average particle diameter of 0.1 μm or less can be easily obtained, and have completed the present invention.

That is, in the present invention, the mechanical pulverizing means is incorporated in the step of producing a zirconium-containing perovskite compound by a wet reaction to increase the production rate of the zirconium-containing perovskite compound, prevent the agglomeration of the produced particles, and increase the average particle size. The fine powder having a diameter of 0.1 μm or less can be manufactured.

In the present invention, as the wet reaction, a normal pressure heating reaction method, a hydrothermal pressurization method or the like is adopted.

The normal pressure heating reaction method means a method of heating and reacting a mixed aqueous solution or slurry of each component element compound at a pH at which the reaction proceeds (usually pH 10 or more) under normal pressure. , A method of reacting a mixed aqueous solution or slurry of each component element compound at a pH at which the reaction proceeds (usually pH 10 or higher) and usually at 100 to 300 ° C. under pressure.

Of the above two reaction methods, the atmospheric pressure heating reaction method is superior in terms of economical efficiency and simplicity of the apparatus. Therefore, if it is possible to produce the fine powder of the zirconium-containing perovskite compound by the atmospheric pressure heating reaction method, it would be better than that.

However, although various studies have been conducted so far on the production of zirconium-containing perovskite compound fine powders by the atmospheric pressure heating reaction method, the presence of zirconium slows down the production rate of the perovskite compound, and therefore agglomerates. Occurs, and only particles having a particle diameter of 0.5 μm or more are obtained, and it has not been possible to obtain a zirconium-containing perovskite compound fine powder having an average particle diameter of 0.1 μm or less.

Accordingly, the inventors of the present invention have conducted extensive studies to solve this problem, and as a result, during the wet reaction, by incorporating mechanical crushing means before solid and hard to crush particles are produced, the average particle size is reduced. It was found that a fine zirconium-containing perovskite compound having a diameter of 0.1 μm or less was obtained, and the present invention was completed based on this.

The present invention will be described in detail below. Examples of the form of the raw material compound usable in the present invention include hydroxides, oxides and salts.

In particular, the hydroxide is less contaminated with impurities, and the hydroxide of the component B (component B in the general formula ABO ₃ , specifically zirconium or zirconium and titanium) is insoluble in water. Since the particle size of the obtained product reflects the particle size of the hydroxide of the component B, it is preferable to use hydroxide in controlling the particle size of the product.

The hydroxides of the component A (the component A in the general formula ABO ₃ , specifically barium or strontium) include barium hydroxide and barium hydroxide.
A hydrate, strontium hydroxide, strontium hydroxide octahydrate, etc. are used.

As the hydroxide of the component B, zirconium salts such as zirconium chloride, zirconium oxychloride, zirconium nitrate and zirconium sulfate, titanium chloride,
Those obtained by hydrolyzing a titanium salt such as titanium sulfate, filtered and washed with water, or those already commercially available as hydroxides can be used.

Since zirconium and titanium have different pHs at the time of gelation, a homogeneous mixed solution of a zirconium salt and a titanium salt is dropped into ammonia water in order to obtain a hydrolysis product having a small compositional variation. However, it is preferable to adopt a method of instantaneous coprecipitation.

As the hydroxides of zirconium and titanium, zirconium salt and titanium salt are used as an aqueous solution as described above, and in addition to the coprecipitated hydroxide hydrolyzed in a mixed system, water hydrolyzed in an independent system is used. A mixture of zirconium oxide and titanium hydroxide can also be used. The same applies when titanium and zirconium alkoxides are used, such as a coprecipitated hydroxide obtained by adding water to a mixed solution to cause hydrolysis, or a mixture of hydroxides obtained by independent hydrolysis. To be done.

As the mechanical crushing means, one utilizing a crushing media is usually employed. As the device, for example, a sand grind mill, a ball mill, a vibration mill or the like is used. These devices are preferably equipped with heating means in order to increase the reaction rate. The vertical sand grind mill is particularly preferable in consideration of the ease of attaching the heating means and the continuous productivity.

As the ground media, zirconia media,
Alumina media, mullite media, etc. are used,
Considering the wear component and strength of the media itself, zirconia media is particularly preferable.

A finer powder tends to be obtained as the media size is smaller, but in actual use, a media size of 0.1 to 5 mm is preferable. When using a media with a diameter smaller than 0.1 mm, it is difficult to handle.
When a media having a diameter larger than mm is used, the pulverizing ability becomes insufficient, and the average particle diameter of the final product becomes larger than 0.1 μm.

By selecting such a media size, the particle size of the resulting zirconium-containing perovskite compound fine powder can be controlled. The particle diameter of the zirconium-containing perovskite compound fine powder can also be controlled by adjusting the stirring speed of a mechanical grinding means such as a sun grind mill.

The atomic ratio of the component A and the component B charged in the raw materials used for the reaction is preferably such that unreacted hydroxide of the component B does not remain. If too much raw material is added, side reactions may occur and it is not economically preferable. Therefore, the A / B atomic ratio is preferably 1 to 50, and 1.2 to 50 is preferable for further improving the reactivity. ..

The slurry concentration during the reaction is A
Expressed in terms of the concentration of the component hydroxide, 0.2 mol / kg water to 2 mol / kg water is preferred because the reaction proceeds smoothly.

The reaction temperature may be 60 ° C. or higher at which the reaction can proceed in the atmospheric pressure heating reaction, but the higher the reaction temperature, the faster the reaction rate. Therefore, from the viewpoint of shortening the reaction time, 80 More preferably, the boiling point of the slurry is not lower than ℃.

The reaction time is not particularly limited as long as it is a time sufficient for completion of the reaction, but usually 2 to 5
Time is preferable.

After the reaction is completed as described above, the crushed media are removed, and the fine powder of zirconium-containing perovskite compound is obtained by filtration, washing with water, drying and calcination by a usual method.

The zirconium-containing perovskite compound fine powder thus obtained has an average particle diameter of 0.1 μm.
The average particle diameter is usually about 0.01 μm as the lower limit of the particle diameter. In other words, it is possible to manufacture a product having a smaller particle size, but a product having a too small particle size may cause aggregation by itself.

Further, as described above, the fine powder of zirconium-containing perovskite compound produced by incorporating the mechanical crushing means is used as barium hydroxide and / or strontium hydroxide as a raw material for component A and zirconium as raw material for component B. When a compound or a hydrolysis product of a zirconium compound and a titanium compound is subjected to a wet reaction between the two, if they are allowed to coexist, the zirconium-containing perovskite compound is allowed to coexist with particles depending on the particle diameter and the amount added. Zirconium-containing perovskite compound fine powder having a controlled diameter can be produced.

In the above method, the average particle diameter of the added zirconium-containing perovskite compound fine powder is 0.
It is preferably from 01 to 0.1 μm. If the average particle size is smaller than 0.01 μm, the agglomeration of the generated particles will be severe in the process of forming the perovskite compound in the wet reaction, and if the average particle size is larger than 0.1 μm, the particle size of the product will be 0.1 μm. Therefore, the purpose of obtaining fine powder cannot be achieved.

In the above method, the amount of the fine powder of zirconium-containing perovskite compound added is 0.01 to 1.
000 mol% is preferable. If the addition amount is less than 0.01 mol%, the average particle size of the product will be larger than 0.1 μm, and the purpose of obtaining fine powder will not be achieved.
When the addition amount exceeds 1000 mol%, the zirconium-containing perovskite compound to which most of the product is added occupies, which makes the addition meaningless.

The reaction conditions in the above method, for example A /
The B atomic ratio, the slurry concentration at the time of reaction, the reaction temperature, etc. may be the same as in the case of incorporating the mechanical crushing means. However, the reaction time may be slightly shorter and may be 1 hour or more.

The mixing method of the hydroxide of the component A, the hydrolysis product of the compound of the component B, the fine powder of the zirconium-containing perovskite compound to be added, etc. is not particularly limited, and before the reaction is started. It should be mixed well.

[0036]

INDUSTRIAL APPLICABILITY In the present invention, by incorporating a mechanical pulverizing means in the wet reaction for producing the zirconium-containing perovskite compound, the production rate of the zirconium-containing perovskite compound is increased to prevent aggregation of the produced particles, It has become possible to produce a fine powder of zirconium-containing perovskite compound having a particle diameter of 0.1 μm or less.

The zirconium-containing perovskite compound fine powder obtained by the present invention has an average particle diameter of 0.
It is possible to control the particle size below 1 μm,
Moreover, the dispersibility is good and the reactivity is also excellent.

[0038]

EXAMPLES Next, the present invention will be described more specifically by way of examples.

Example 1 2020 g of zirconium oxychloride octahydrate was added to pure water 7
It was dissolved in 360 g and stirred for 1 hour. This aqueous solution 10
The solution was added dropwise to 30 liters of aqueous ammonia having a weight% of pH 9.
A white slurry of 2 was obtained.

The slurry was filtered and washed with water, then reslurried, and then heated to 60 ° C., acetic acid was added to adjust the pH.
It was aged at 6.0 for 40 minutes. After aging, filtration and washing with water gave a cake of hydrous zirconium hydroxide gel having a solid content of 20% by weight.

50 g of the obtained cake (0.08 mol of zirconium), 35 g of barium hydroxide octahydrate
(0.11 mol as barium content), 600 g of zirconia media having a diameter of 0.5 mm and 100 g of pure water were placed in a reaction vessel made of alumina porcelain having an internal volume of 500 ml equipped with a rubber heater and stirred at 1000 rpm for 30 minutes. The temperature was raised with continued stirring, and the mixture was refluxed for 5 hours. After the reflux, zirconia media was removed from the slurry, and then the slurry was filtered, washed with water and dried.

The product obtained as described above was confirmed by analysis by X-ray diffraction to be barium zirconate, and the average particle size observed by a scanning electron microscope is shown in FIG. Thus, it was 0.03 μm.

FIG. 1 is a 100,000 times scanning electron micrograph showing the particle structure of barium zirconate produced in Example 1. As shown in this FIG.
The barium zirconate produced by was a fine powder pulverized to a state close to the primary particle unit.

Comparative Example 1 123 g of the hydrous zirconium hydroxide gel cake obtained in Example 1 (0.2 mol as zirconium content) and 88 g of barium hydroxide octahydrate (0.2 as barium content).
8 mol) and 252 g of pure water were placed in a reaction vessel made of polytetrafluoroethylene having an internal volume of 500 ml under a nitrogen atmosphere, and the mixture was stirred by a polytetrafluoroethylene stirring blade to 1
The mixture was stirred at 000 rpm for 1 hour. The temperature was raised while stirring was continued, and the mixture was refluxed for 8 hours. After the reflux, the slurry is filtered, washed with water,
Dried.

The product obtained as described above was confirmed to be barium zirconate as a result of analysis by X-ray diffraction, and the average particle size observed by a scanning electron microscope is shown in FIG. Thus, it was 1 μm.

FIG. 2 is a scanning electron micrograph showing the barium zirconate particle structure produced in Comparative Example 1 at a magnification of 6000 times. As shown in FIG. 2, the barium zirconate produced in Comparative Example 1 was a secondary particle having a large particle size in which primary particles were aggregated in a spherical shape.

Example 2 50 g of the hydrous zirconium hydroxide gel cake obtained in Example 1 and 600 g of zirconia media with a diameter of 0.5 mm
And 70g of pure water was put into a reaction vessel made of alumina porcelain, and 1
After stirring at 000 rpm for 30 minutes, the temperature was raised while continuing stirring.

Immediately after the start of reflux, 60 g of barita water (barium hydroxide aqueous solution) having a concentration of 27% by weight prepared and boiled in a nitrogen atmosphere was added (the atomic ratio of A / B was 1.2). And continued to reflux again.

At this time, the reflux time was changed and the relationship between the amount of barium zirconate produced and the reaction time was investigated. The result is shown in FIG.

The amount of barium zirconate produced was calculated from the peak area of the (110) plane of the cubic perovskite by X-ray diffraction.

As shown in FIG. 3, in the case of Example 2, the reaction time was about 1 hour, and the production amount of barium zirconate reached almost 100%, and the reaction proceeded extremely fast.

The barium zirconate produced when the reaction time was 2 hours was observed by a scanning electron microscope photograph, and the average particle diameter was 0.03 μm.

Comparative Example 2 80 g of the hydrous zirconium hydroxide gel cake obtained in Example 1 and 110 g of pure water were placed in a reaction vessel made of polytetrafluoroethylene having an internal volume of 500 ml, and 1000 rpm with a stirring blade made of polytetrafluoroethylene. After stirring for 1 hour, the temperature was raised while continuing stirring.

Immediately after the start of the reflux, 96 g of 27% by weight barita water (barium hydroxide aqueous solution) prepared and boiled under a nitrogen atmosphere (at an A / B atomic ratio of 1.2) was added. The reflux was continued again.

At this time, the reflux time was changed, and the relationship between the amount of barium zirconate obtained and the reaction time was examined in the same manner as in Example 2. The result is shown in FIG.
Shown in.

As shown in FIG. 3, in the case of this comparative example 2, the production amount of barium zirconate finally reached 100% after about 10 hours of reaction time, which means that the reaction was slower than that of the example 2. ..

The barium zirconate obtained when the reaction time was 10 hours was observed by a scanning electron microscope photograph. As a result, the average particle diameter was 1 μm.

Example 3 A reaction was carried out in the same manner as in Example 1 except that the diameter of zirconia media was changed to 5 mm.

As a result of X-ray diffraction analysis, the obtained product was confirmed to be barium zirconate, and the average particle size observed by a scanning electron micrograph was 0.
It was 1 μm.

Example 4 532 g of titanium tetrachloride aqueous solution (containing 16.4 wt% as titanium) (1.8 mol as titanium), 252 g of zirconium oxychloride octahydrate (0.78 mol as zirconium) and pure water A mixed solution containing 2830 g was prepared and stirred for 1 hour.

This aqueous solution was added with 10% by weight of ammonia water 1.
It was dropped into 2 liters to obtain a white slurry having a pH of 9.0. The slurry is filtered, washed with water, reslurried, heated to 60 ° C., and acetic acid is added to adjust the pH to 40.
Aged for minutes. After aging, filtration and washing with water gave a coprecipitated cake of hydrous titanium hydroxide and hydrous zirconium hydroxide having a solid content of 12% by weight.

62 g of the obtained cake (titanium + zirconium content 0.08 mol), barium hydroxide octahydrate 35 g (barium content 0.11 mol), diameter 0.
600 g of 5 mm zirconia media and 85 g of pure water were placed in a reaction vessel made of alumina porcelain, and the amount was 30 at 1000 rpm.
After stirring for a minute, the temperature was raised while stirring, and the mixture was refluxed for 2 hours. After the reflux, zirconia media was removed from the obtained slurry, and then filtered, washed with water and dried.

The product obtained as described above was confirmed by X-ray diffraction analysis to be a solid solution of barium zirconate and barium titanate, and the average observed by scanning electron micrographs. Particle size is 0.03μ
It was m.

Example 5 Instead of barium hydroxide octahydrate, 29 g of strontium hydroxide octahydrate (0.1 g as strontium content)
The reaction was performed in the same manner as in Example 1 except that 1 mol) was used.

The product thus obtained was confirmed to be strontium zirconate as a result of X-ray diffraction analysis, and the average particle size observed by scanning electron micrograph was 0.02 μm.

Example 6 616 g of the hydrous zirconium hydroxide gel cake obtained in Example 1 (1.0 mol as the zirconium content) and 442 g of barium hydroxide octahydrate (barium content of 1.
4 mol) and 1260 g of pure water were placed in a reaction vessel made of polytetrafluoroethylene having an internal volume of 3 liters under a nitrogen atmosphere, and stirred at 300 rpm for 1 hour with a stirring blade made of polytetrafluoroethylene.

To the slurry obtained as described above, 14 g (0.05 mol) of fine barium zirconate powder produced in Example 1 and having an average particle diameter of 0.03 μm was added, and the mixture was further stirred for 1 hour. While continuing stirring, raise the temperature,
Refluxed for 8 hours. After the reaction, the slurry was filtered, washed with water and dried. In this case, the amount of barium zirconate added to zirconium hydroxide was 5 mol%.

The product obtained as described above was confirmed by analysis by X-ray diffraction to be barium zirconate, and the average particle size observed by scanning electron micrograph was 0.09 μm. there were.

Examples 7 to 9 The reaction was carried out under the same conditions as in Example 6 except that the addition amount of the barium zirconate fine powder produced in Example 1 and having an average particle diameter of 0.03 μm was changed.

Average particle size 0.03 μm in each example
Table 1 shows the amount of barium zirconate fine powder added and the average particle size of the obtained barium zirconate observed by a scanning electron microscope photograph.

[0071]

[Table 1]

As shown in Table 1, the average particle diameter is 0.03 μm.
It can be seen that the average particle diameter of the obtained barium zirconate changes depending on the addition amount of barium zirconate of m, and the particle diameter of the generated barium zirconate can be controlled by the addition amount of fine barium zirconate. ..

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (magnification: 100,000) showing a particle structure of barium zirconate produced according to Example 1 of the present invention.

FIG. 2 is a scanning electron microscope photograph at a magnification of 6000 showing the particle structure of barium zirconate produced in Comparative Example 1.

FIG. 3 is a graph showing the relationship between the amount of barium zirconate produced and the reaction time in Example 2 and Comparative Example 2.

Claims (4)

[Claims] 1. A barium compound and / or strontium compound is wet-reacted with a zirconium compound or a zirconium compound and a titanium compound to give a compound of the general formula ABO ₃ (wherein A is barium and / or strontium and B is zirconium or Zirconium and titanium) represented by the general formula ABO ₃ to produce a fine powder of the zirconium-containing perovskite compound represented by the general formula ABO _{3 in} which the wet reaction is allowed to proceed while mechanically pulverizing. A method for producing a fine powder of zirconium-containing perovskite compound, comprising: 2. The barium compound is a hydroxide or oxide of barium, the strontium compound is a hydroxide or oxide of strontium, the zirconium compound is a hydrolysis product of the zirconium compound, and the zirconium compound and the titanium compound are The method for producing a fine powder of zirconium-containing perovskite compound according to claim 1, which is a hydrolysis product of them and is subjected to a wet reaction at 60 ° C. or higher. 3. The method for producing fine powder of zirconium-containing perovskite compound according to claim 1, wherein the mechanical pulverizing means is a sand grind mill. 4. Barium hydroxide and / or strontium hydroxide, and a hydrolysis product of a zirconium compound or a zirconium compound and a titanium compound in the presence of the zirconium-containing perovskite compound fine powder produced by the method according to claim 1. A method for producing a fine powder of a zirconium-containing perovskite compound, which comprises subjecting a hydrolyzate of the above to a wet reaction.