JPS62226812A - Manufacturing method of easily sinterable perovskite powder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a raw material powder of a perovskite-type structural compound and its solid solution (hereinafter referred to as perovskite).

Perovskites are widely used as functional ceramics such as piezoelectrics, dielectrics, semiconductors, sensors, and optoelectronic materials.

Recently, the sophistication of functional ceramics has progressed, and a technology has been developed that can efficiently produce large quantities of low-cost perovskite raw material powder that is easy to sinter, has uniformity, has high bulk density, and can meet these demands. is requested.

Conventionally, the method for manufacturing perovskite raw material powder is as follows:
Dry method and coprecipitation method are known.

The dry method is a method in which compounds of constituent raw materials are mixed in a dry method and then calcined. However, with this method, it is difficult to obtain a raw material powder with a uniform composition, so it is difficult to obtain a perovskite with excellent functionality, and the sinterability is also not sufficient.

The coprecipitation method is a method in which a mixed solution is prepared by combining all of the constituent components, a precipitate-forming liquid such as an alkali is added to the mixed solution to cause coprecipitation, and this coprecipitate is dried and calcined.

According to this coprecipitation method, it is easy to obtain powder with excellent uniformity, but
Due to its uniformity, the particles tend to coagulate to form secondary particles during precipitate formation, drying or calcination, resulting in poor sinterability.

In addition, in the coprecipitation method, if the precipitate forming ability of each component with respect to the precipitate forming solution is not the same, for example, the acid component is substantially 10
Although 0% precipitate is produced, substantially all of the other components may not be able to produce precipitate, and it may be difficult to obtain the desired composition.

Furthermore, perovskite functional materials very often contain lead and titanium at the same time. When producing such materials industrially, it is desirable to use inexpensive titanium tetrachloride as the titanium raw material. However, when this is used in the coprecipitation method,
It is difficult to use because the chlorine ions in titanium tetrachloride react with lead to form a white precipitate. In this case, the formation of this white precipitate can be prevented by using titanium oxynitrate [TiO(NO3)2] instead of titanium tetrachloride, but titanium oxynitrate is expensive and is not practical for industrial production. .

[Purpose of the Invention] The present invention provides a method that can eliminate the drawbacks of conventional coprecipitation methods, and further improves ease of sintering, uniformity, and
The object of the present invention is to provide a method for efficiently producing perovskite and its solid solution raw material powder that satisfies the four requirements of low cost and high bulk density.

[Structure of the Invention] As a result of intensive research to achieve the above object, the present inventors found that the general formula ABO3 (where A is one of the oxygen-12-coordinated metal elements)
B represents one or more oxygen hexacoordination metal elements. ) When manufacturing the raw material powder of perovskite represented by When carried out by a method of producing a homogeneous particle, the drawbacks of the conventional method can be improved, and a precipitate of uniform particles in which fine particles of component A and component B are highly mutually dispersed can be obtained. The raw material powder produced has a narrow particle size distribution, consists of fine particles with uniform particle size, and has a uniform composition, making it extremely industrially advantageous to produce easily sinterable perovskite powder, more specifically, easily sinterable perovskite raw material powder. The present invention was achieved based on the discovery that it is possible to produce

The present invention provides a solution containing component A (wherein A represents IM or two or more types of oxygen-12-coordinated metal elements) and a solution containing component B (however, B represents one type or two or more of oxygen-12-coordinated metal elements). ) is brought into contact with a precipitate-forming solution in multiple stages to sequentially generate precipitates, and the resulting precipitates are calcined to produce a perovskite-type structural compound represented by the general formula ABO3. and its solid solution (hereinafter referred to as perovskite), at least one of component A
The present invention relates to a method for producing easily sinterable perovskite powder, characterized in that precipitate formation of seeds is carried out by bringing them into contact with a plurality of precipitate forming liquids.

According to the present invention, the drawbacks of conventional coprecipitation methods can be overcome.

Examples of the oxygen-12-coordinated metal element of the component A in the general formula ABO3 include rare earth elements such as pb, 13a, Ca, Sr, and La. Further, as the oxygen hexacoordination metal element of the B component, for example, Ti.

Zr, Mg, Sc, Hf, W, Nb, Ta, Cr.

Mo, Mn, Fe, Co, Ni, Zn, Cd.

Examples include AI, 3n, As, Bi, etc.

Component compounds for preparing an aqueous solution of a compound containing metal elements of component A and component B of perovskite include, but are not particularly limited to, their hydroxides, carbonates, oxysalts, sulfates, nitrates, These include inorganic salts such as chlorides, organic acid salts such as acetates and oxalates, and oxides. These are generally used as aqueous solutions, but if they are not soluble in water, they may be dissolved by adding an appropriate acid.

Also, hardly soluble oxides such as Nb and W! A 1J turbid solution can be used.

Examples of the precipitation forming liquid used in the present invention include ammonia (water), ammonium carbonate, ammonium hydrogen carbonate, caustic alkali, oxalic acid, ammonium oxalate, and alkyl amines.

The present inventors have found that in order to make the precipitate of the constituent components have fewer aggregates and have good dispersibility, the primary particles of the precipitate should be non-uniform, and the secondary particles, which are the aggregates, should be uniform; Furthermore, we have found that it is important that the secondary particles have an appropriate particle diameter of about submicrons.

A method that satisfies this requirement is to bring a solution containing each component into contact with a precipitate-forming solution in multiple stages to sequentially generate precipitates (hereinafter referred to as the "multi-stage wet method"). , when at least one of the A components produces a precipitate, a plurality of precipitate forming solutions are used and a solution containing the A component is brought into contact with the plurality of precipitate forming solutions to produce a precipitate. I discovered that the effects are increasing.

As the plurality of precipitate forming liquids used in the present invention, two or more types of precipitate forming liquids are appropriately selected from among the above precipitate forming liquids.

Specific examples include ammonia water-oxalate system, ammonium carbonate-ammonium oxalate system, ammonia-alkylamine system, oxalic acid-alkylamine system, ammonium bicarbonate-ammonium oxalate system, ammonium carbonate-ammonium oxalate system. Suitable examples include combinations that give precipitates of different A component compounds, such as aqueous ammonia systems and ammonium oxalate-alkylamine systems. These plural precipitate forming solutions may be used as a mixed solution, or may be added and mixed simultaneously during precipitate formation. Specific examples of the alkylamine include primary amines having a lower alkyl group such as methylamine, ethylamine, propylamine, butylamine, primary amines having a lower alkyl group such as cyclohexylamine, dimethylamine, diethylamine, etc. Mention may be made of tertiary amines and tertiary amines having a lower alkyl group such as triethylamine.

The specific method for producing precipitates of each component is as follows:
For example, the A component or the A component and the B component are brought into contact with a plurality of precipitate-forming liquids and one or more kinds of solutions prepared by dispersing and dissolving components A or a compound containing the metal elements of the A component and the B component in water. A method of forming a precipitate of component B or a solution of a compound containing a metal element of component B and component A with a precipitated sensitive liquid to produce a precipitate of component B or component B and component A, or Examples include a method of forming a precipitate in a different order from the above.

To form a precipitate of the constituent components, an aqueous solution of each constituent component may be added to the precipitate forming liquid while stirring the precipitate forming liquid, or vice versa.

It is preferable that the addition be carried out while sufficiently stirring the liquid.

In addition, when forming a precipitate, for example, after forming a precipitate of one component, the precipitate is washed with water to remove anions, the precipitate is dispersed in fresh water or alcohol, and then an aqueous solution of another component and a precipitate forming solution are mixed. may be added to form a precipitate.

In addition to component A and component B, when adding trace components to control the Perobus force, sinterability and properties of the
When preparing a solution of component B, trace amounts of these components may be added. Furthermore, if necessary, as described above, the precipitation of component A and component B may be formed in multiple stages, or may be caused to precipitate alternately.

The precipitate obtained by the above method is washed, filtered, dried, and then calcined by a conventional method. Drying may be performed under atmospheric pressure or under reduced pressure.

If the calcination temperature is too low, the dehydration and thermal decomposition of the precipitate will be insufficient, and if it is too high, the powder will become coarse. be.

[Example] The present invention will be explained in more detail by showing Examples and Comparative Examples below.

Example 1 8.860g of niobium oxide (Nb20s) powder was added to 0.5N
Dispersed in 200m/NH40H, and to this 39.5g of ammonium hydrogen carbonate and 71.1g of ammonium oxalate.
A solution prepared by dissolving 2121.163 g of strontium nitrate [Sr (NO3) in 500 ml of water was added thereto, and a solution prepared by dissolving 2121.163 g of strontium nitrate [Sr (NO3) in 500 ml of water] was gradually added with stirring to form a precipitate.

The precipitated anastomosis solution was allowed to stand still, the supernatant liquid was removed, water was newly added and the mixture was sufficiently stirred, and then the solution was left to stand again and the supernatant liquid was removed. To the precipitate-containing solution obtained by repeating this (tJ! filtration operation 5 times), an aqueous solution of 15mj! of diethylamine in 100mf of water was added, and to this solution was added zinc nitrate [Zn (NO
3) 2 ・61120 ] 9. 916 g to 3 parts water
00 ml of the solution was gradually added to form a precipitate. This precipitate was filtered, dried, and then calcined at 950° C. for 2 hours to obtain Sr (Zn+/3Nb2/3) 03 powder. The elemental composition of this calcined powder is the same as that of the raw material, and the particle size was observed using a transmission electron microscope.
．． The particles were uniform in size from 3 to 0.4 μm. 1 of this powder
, 5t/cm2, and sintered at 1500°C for 2 hours. Its density was 5.603 g/cc.

Example 2 In Example 1, barium nitrate [Ba (NO3) 2113.067
13a (Zrz73Ta2/
3) A calcined powder of No. 03 was produced. The elemental composition of this calcined powder was the same as that of the charged powder, and when the particle size was observed with a transmission electron microscope, it was found to be uniform particles of 0.3 to 0.4 μm.

Further, this calcined powder was fired in the same manner as in Example 1 to obtain a sintered body. Its density was 7.865 g/cc.

Example 3 In Example 1, 30 ml of diethylamine and 71.1 g of ammonium oxalate were used instead of ammonium hydrogen carbonate and ammonium oxalate as the precipitation forming liquid,
Also, instead of zinc nitrate, magnesium nitrate [Mg (N
O3)2 ・Sr (Mg+73Nb2
/3) A calcined powder of 03 was produced. The elemental composition of this calcined powder was the same as that of the raw material.

Further, the calcined powder was fired in the same manner as in Example 1 to obtain a sintered body.

Its density is 5. It was 243 g/cc.

Comparative Example 1 A calcined powder was produced in the same manner as in Example 1 except that ammonium oxalate was not present. The elemental composition of this calcined powder was the same as that of the charged powder, but when the particle size was observed with a transmission electron microscope, it was found to have a wide distribution of 0.1 to 1.0 μm.

Further, the calcined powder was fired in the same manner as in Example 1 to obtain a sintered body. Its density was 5.320 g/ccT.

[Effects of the Invention] When producing the raw material powder of perovskite represented by the general formula ABO3 and its solid solution, unlike the conventional coprecipitation method in which all components are coprecipitated at the same time, in the presence of multiple precipitate forming solutions, Because the A and B components are precipitated sequentially, components that were difficult to precipitate 100% with conventional methods and all other components can be precipitated substantially completely, and two or more phases can be precipitated. As a result of obtaining a precipitate in which the phases are more highly interdispersed, the precipitate does not agglomerate during formation or coagulate during drying or calcination, making it possible to produce powder with high bulk density and easy sintering with good reproducibility. can do.

In addition, in this process, each phase is highly mutually dispersed, so that the calcined material achieves sufficient uniformity. Further, since the process is simple, it has excellent effects such as being able to obtain easily sinterable powder with good reproducibility and at low cost.

Claims (1)

[Claims] A solution containing component A (where A represents one or more types of oxygen-12-coordinated metal elements) and a solution containing B component (however, B represents one or more types of oxygen-6-coordinated metal elements). ) is brought into contact with a precipitate-forming solution in multiple stages to sequentially generate precipitates, and the resulting precipitates are calcined to produce a perovskite-type structural compound represented by the general formula ABO_3 and its solid solution. A method for producing easily sinterable perovskite powder, characterized in that, in producing a raw material powder of perovskite (hereinafter referred to as perovskite), precipitation of at least one component A is brought into contact with a plurality of precipitation forming liquids.