JPH04132614A - Production of perovskite-type multiple oxide powder - Google Patents

Abstract

PURPOSE:To produce the subject multiple oxide powder having fine particle size and narrow particle size distribution width by reacting a monodispersed amorphous oxide of a tetravalent metal element in an aqueous solution of an alkaline-earth metal and an alkali metal hydroxide under a specific condition and baking the reaction product. CONSTITUTION:A monodispersed amorphous oxide is produced by hydrolyzing at least one kind of alkoxide of tetravalent metal element B (Ti, Zr or Sn). The obtained slurry is added to an aqueous solution containing 1mol (based on 1mol of the monodispersed amorphous oxide in the slurry) of at least one kind of alkaline-earth metal A (Ba, Sr, Mg or Ca) and 1-4mol of an alkali metal hydroxide (e.g. NaOH) or an amine (e.g. methylamine) and is made to react at 60-98 deg.C to form a perovskite-type multiple oxide. The objective perovskite-type multiple oxide powder (ABO3) having large specific surface area and high surface activity can be produced by baking the obtained multiple oxide at 400-600 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing perovskite-type composite oxide powder.

(Prior art) Conventionally, the method for producing perovskite-type composite oxide powder involves using carbonates and oxides as constituent elements as raw materials, mixing them in a predetermined ratio, and then calcining at a temperature of 1000°C or higher. The dry method of grinding and pulverizing is generally used. However, with this method, it is impossible to uniformly disperse the raw material powder at the molecular level, and therefore, not only is it impossible to obtain microscopically uniform powder, but also agglomeration and particle growth occur during the manufacturing process. Therefore, there was a problem that fine powder could not be obtained.

On the other hand, as a means to obtain finer particles than the dry method, a precipitate or a coprecipitate is generated by a liquid phase reaction, which is filtered, washed, and dehydrated to remove unnecessary ions, and then dried. A wet method has been proposed in which the material is then roasted. For example, (1) Journal of the American Ceramic Society, Vol. 46, pp. 359-365 (1963), P. K. Gallagher et al. (2) Journal of American Ceramic Society, Vol. 52, 523-
526 (1969), K., S., Mazd.
A method of producing barium titanate by hydrolyzing a mixed solution of barium and titanium alkoxides according to iyaS et al. Furthermore, (3) Kochi University Hydrothermal Chemistry Laboratory Report Vol. 2, No. 5 (+978) , titanium oxide and barium hydroxide were mixed at a Ba/Ti ratio of 1.2, and Oh!・
A method of producing barium titanate by hydrothermal treatment at 110 to 130'C in a crepe has been proposed.

(Problem to be solved by the invention) However, in the method (1) above, barium titanate is obtained by roasting the product at high temperature, so particle aggregation is likely to occur as in the same phase reaction. Moreover, since the oxalic acid cannot be recovered and reused, there is a problem in that the cost is high. In addition, although method (2) can produce submicron fine powder, the cost is extremely high because alkoxides are used for both barium and titanium, and furthermore, these alkoxides are not present in the atmosphere. Because it is extremely unstable, it requires a special atmosphere to prevent hydrolysis due to moisture in the atmosphere during synthesis, and has low solubility in organic solvents, resulting in low productivity per batch. . Furthermore, (3)
In this method, since the reaction is carried out in an autoclave, a container that can withstand high temperature and pressure is required, which makes the reaction equipment expensive, and there is also the problem of low productivity because it is a batch method.

Moreover, with any of the above methods, there was a problem in that monodisperse barium titanate powder could not be obtained.

Therefore, it is an object of the present invention to make it possible to inexpensively produce a monodisperse perovskite-type composite oxide powder having fine particles, a large specific surface area, and a uniform particle size with a narrow particle size distribution width. It is something.

(Means for Solving the Problem) The present invention provides, as a means for solving the problem, a general formula: ABO3 (wherein A is at least one element among alkaline earth metals, B is at least one (represents a tetravalent metal element)
In the method for producing a perovskite-type composite oxide powder represented by The element constituting the A site of the general formula in an equimolar amount relative to the monodispersed amorphous oxide is added to an aqueous solution containing an alkali hydroxide or an amine in an amount of 1 to 4 times the mole, and the mixture is reacted at 60 to 98°C. Perovskite type complex oxide 400-6
It is roasted at 00°C.

Typical alkaline earth metals constituting the A site include barium (Ba), strontium (Sr),
Macunium (Mg) and calcium (Ca) can be used alone or in combination depending on the desired perovskite-type composite oxide. Typical tetravalent metal elements constituting the B site include titanium (Ti), sulfnium (Zr), and tin (Sn), and these can be used alone or in combination of two or more. In addition,
Yttrium and rare earth elements can be dissolved in the A site.

In this case, at least one of these alkoxides is
It is included in an alkoxide solution of the elements constituting the site and hydrolyzed.

Further, as the alkoxylate of the metal element constituting the B site, any one can be used, or it is desirable that the number of carbon atoms in the alkoxy group is 15 or less, preferably 8 or less.

A typical example of titanium alkoxide is titanium isobutoxide (T + (OC4H5)4
), titanium isopropoxy l' (T i (OC, H7)
4), Mbutkin/!・Reethanol-aminate titanium, shiftkin (2 (hydroxyethylamine)
Etkin) titanium (Ti(C4H,O), .[N(C,
H40H)2(C3H40)]2) and the like, but are not limited to these.

Examples of the alkali hydroxide include thorium hydroxide, potassium hydroxide, and lithium hydroxide, and these can be used alone or in combination.

Examples of amines include aliphatic amines such as methylamine, dimethylamine, trimethylamine, and ethylamine, o-, m-, p-1-luidine, N, N'
Representative examples include aromatic amines such as -dimethylhensylamine, but are not limited thereto.

Further, it is preferable that the roasting is carried out in order to completely remove organic substances, and the temperature is preferably a temperature that does not cause particle growth of the produced powder, usually within the range of 400 to 600°C.

(Function) In the method of the present invention, first, a monodispersed amorphous oxide powder of the B-site constituent element is produced, and this is mixed with an alkaline earth metal hydroxide, which is the A-site constituent element, in an alkaline aqueous solution with 60 to 98% By performing the reaction at a temperature of 0.degree. C., it is possible to allow the reaction to proceed mildly and to produce microscopically uniform ultrafine particles. Furthermore, by roasting the produced perovskite-type composite oxide powder at a temperature that does not cause particle growth, agglomeration of particles and a decrease in surface activity are prevented.

Examples of the present invention will be described below.

(Example 1) A mixed solution was prepared by adding 10 mC of titanium isopropoxide to 350 ml of ethyl alcohol, and while stirring, added 15 m of pure water (and 135 m of ethyl alcohol) to the mixed solution in a 10 mM portion. titanium isopropoxide is added dropwise at a speed of Obtain titanium powder slurry.

11.025g of barium hydroxide in boiling pure water IQ,
Potassium hydroxide], 0.5 g was added and dissolved, and the monodispersed amorphous titanium oxide slurry was added to the solution and reacted for 5 hours while maintaining the temperature at 90 to 95°C. During the reaction, boiled pure water is occasionally added to maintain the volume of the reaction solution at 1ρ.

After the reaction is completed, the barium titanate produced is filtered off, and the separated barium titanate powder is poured into hot water and the potassium ions are repeatedly washed and removed while stirring at high speed. N,N'-dimethylhensylamine is added so that the pH of the cleaning solution does not fall below 10.

Next, the water content of the washed and filtered barium titanate powder was replaced with Echinene (trade name: a solution of 10% isopropyl alcohol mixed with ethanol), and then evaporated to dryness using a rotary eno-borator, and then dried for 450 minutes. C
The particles were roasted for 2 hours to completely remove the organic matter adsorbed on the particle surface, and barium titanate powder was obtained.

When the obtained powder was analyzed by X-ray diffraction, it was found to be a single phase of cubic barium titanate. Also, that Ba and T
It was confirmed that the molar ratio of i (Ba/Ti) was 1.1.

Furthermore, when this powder was observed using a transmission electron microscope, the particle size was 0.2 to 0.3 μm, and the distribution width was narrow and uniform. In addition, when the specific surface area of the powder was measured, it was found to be 14.
It was 3m2/g.

(Example 2) Prepare a mixed solution by adding 0 ml of titanium isopropoxide to 350 mC of ethyl alcohol, and add 15 mK of pure water to the mixed solution while stirring! A mixed solution of ethyl alcohol and ethyl alcohol (135 mρ) was added dropwise at a rate of ]Omρ/min to be hydrolyzed to produce monodisperse amorphous titanium oxide. This reaction solution is separated into solid and liquid by centrifugation, and the supernatant is removed to obtain a monodisperse amorphous titanium oxide powder slurry.

Boiled pure water 1 (!) barium hydroxide 6.625g, strontium hydroxide 3.721g, potassium hydroxide 10
5 g of titanium oxide is added and dissolved, and the monodispersed amorphous titanium oxide slurry is added thereto, and the mixture is reacted for 5 hours while maintaining the temperature at 90 to 95°C. During the reaction, boiling pure water was added to the reaction solution from time to time to maintain the total amount at 1 g.

After the generated barium/strontium titanate powder is filtered out, it is poured into hot water, stirred at high speed, and the potassium ions are washed and removed repeatedly. Add N,N dimethylbenzylamine so that the pH of the cleaning solution does not fall below 10.

Next, after replacing the water content of the washed barium/strontium titanate powder with excimum, it is distilled under reduced pressure using a low-pressure evaporator to remove the excimum.
The particles were roasted at 50'C for 2 hours to completely remove the organic matter adsorbed on the particle surface to obtain barium/strontium titanate powder.

The composition of the obtained powder is (Bao, S ro +)'r
There was io*.

(Example 3) 350 mQ of ethyl alcohol and 8.99 m of titanium isopropokit (!, Zirconium Lobe I Kit 136
Prepare a mixed solution by adding mρ, stir this mixed solution, and then add 15 ml of pure water and ethyl alcohol],
A mixture of 35 m and 35 m ρ is added dropwise at a rate of 1 mρ/min and hydrolyzed to produce a monodisperse composite oxide. This reaction liquid is separated into solid and liquid by centrifugation, and the bi-clear liquid is removed. to obtain a monodisperse composite oxide powder slurry.

Barium hydroxide in 1ρ of boiled pure water] 1.025g,
105 g of potassium hydroxide is added and dissolved, the monodisperse composite oxide slurry is added thereto, and the mixture is reacted for 5 hours while maintaining the temperature at 90 to 95°C. During the reaction, boiling pure water is occasionally added to the reaction solution to maintain the total volume at 1ρ.

After filtering the produced barium zirconate titanate powder, it is poured into hot water and stirred at high speed, and the potassium ions are washed and removed repeatedly. N N'-dimethylbenzylamine is added so that the pH of the cleaning solution does not fall below 10.

Next, the washed barium zirconate titanate powder was washed with Kofukin and its moisture was replaced with Equinene, and then dried by distillation under reduced pressure using a rotary evaporator, and further roasted at 450'C for 2 hours. The organic matter adsorbed on the particle surface was completely removed to obtain barium titanate zirconate powder.

The composition of the obtained powder is B aTlo9oZ ro, +o
It was o3.

(Example 4) Titanium isopropoxy l in 350 mρ of ethyl alcohol
"0.035 mol, Ce (○c4r-+9) 30.00
Add 16 mol of pure water to prepare a mixed solution, and add 15 ml of pure water and 1 ml of ethyl alcohol to the mixed solution while stirring.
A mixed solution of 35 m/min is added dropwise at a rate of 1 m (l/min) for hydrolysis to produce a monodisperse composite oxide. This reaction solution is separated into solid and liquid by centrifugation, and the supernatant liquid is A monodisperse composite oxide slurry is obtained by removal.

10.537g of barium hydroxide in boiling pure water IQ,
5.6 g of sodium hydroxide is added and dissolved, and the monodisperse composite oxide slurry is added to the solution and reacted for 5 hours while maintaining the temperature at 90 to 95°C. During the reaction, boiling pure water was added to the reaction solution from time to time to maintain the total volume at IQ.

After the reaction is completed, the generated (Ba,Ce)TiO3 powder is filtered off, and the separated (Ba,Ce)TiO3 powder is poured into hot water and the thorium ions are washed and removed repeatedly while stirring at high speed. Make sure that the pH of the cleaning solution does not fall below 10.
Add N N'-dimethylbenzylamine.

Next, the washed and filtered (Ba,Ce)TiO3 powder was washed with exhaust to replace water with exhaust, and then dried by distillation under reduced pressure using a low evaporator, and further dried at 450°C. The organic matter adsorbed on the particle surface was completely removed by roasting for 2 hours to obtain (Ba, Ce)Tio3 powder.

The obtained (Ba,Ce)Ti○3 powder was analyzed and found to be (
B a Q15f+Ceo, o45) T I O3 was there.

(Effect of the invention) As is clear from the following explanation, according to the present invention, B
A monodispersed amorphous oxide powder of the site constituent elements is produced, and this is reacted with the hydroxide of the supra-alkali metal, which is the A site constituent element, in an alkaline aqueous solution at 60 to 98°C to produce a composite oxide. Because the powder is roasted at a temperature that does not cause particle growth, it is possible to obtain a perovskie-type composite oxide powder that is fine, has a narrow particle size distribution, has a large specific surface area, and has high surface activity. Moreover, the alkali hydroxide solution after filtering and separating the perovskite type composite oxide powder can be reused, and an increase in manufacturing costs can be suppressed.

Furthermore, unlike conventional methods, sulfuric acid, chloride, nitrate, etc. are not used as raw materials, so there is no risk of environmental pollution that would require treatment of waste acid solution.

In addition, the A site constituent elements and the B' (ite constituent elements) are
Since the reaction is carried out at a molar ratio of 1, unlike the conventional method in which the A-site constituent elements are reacted in excess, there is no need to remove excess ions of the A-site constituent elements. Moreover, unlike hydrothermal synthesis, it does not require a high-temperature, high-pressure container, so it can be manufactured using inexpensive equipment, and excellent effects can be obtained, such as reducing the cost I of perovskite-type composite oxide powder. .

Patent applicant: Murata Manufacturing Co., Ltd. Agent: Patent attorney: 1 person named Haka

Claims (2)

[Claims] (1) General formula: ABO_3 (In the formula, A represents at least one element among alkaline earth metals, and B represents at least one tetravalent metal element)
In the method for producing a perovskite-type composite oxide powder represented by A perovskite produced by adding an equimolar amount of the element constituting the A site of the general formula to the dispersed amorphous oxide to an aqueous solution containing 1 to 4 times the mole of alkali hydroxide or amine and reacting at 60 to 98 ° C. Type composite oxide 400-6
A method for producing perovskite-type composite oxide powder, which comprises roasting at 00°C. (2) The method for producing a perovskite-type composite oxide powder according to claim 1, wherein the element constituting the B site is at least one selected from the group consisting of titanium, zirconium, and tin. (3) The method for producing a perovskite-type composite oxide powder according to claim 1, wherein at least one of yttrium and a rare earth element alkoxide solid-dissolved in the A site is contained in an alkoxide of an element constituting the B site and hydrolyzed.