JPS63100001A - Preparation of raw material powder for perovskite - Google Patents

Abstract

PURPOSE:To obtain easily sinterable uniform fine particles of raw material for a perovskite type compd. expressed by the general formula ABO3 by calcining a mixture of a compd. contg. the component A and a compd. contg. the component B in the presence of a flux. CONSTITUTION:The raw material powder for a perovskite type compd. expressed by the general formula ABO3 and its solid solution (wherein A is at least one metallic element having a coordination number 12 for oxygen, and B is at least one metallic element having a coordination number 6 for oxygen) are prepd. by calcining a mixture contg. the component A and a compo nent B. In the stage of calcination of the compds. A and B, the calcination is performed in the presence of a flux. For the flux, a compd. which is not decomposed but melts in the calcination stage is preferred. Chlorides, such as KCl, NaCl, BaCl2, SrCl2, CaCl2, are particularly preferred.

Description

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

Perovskites are widely used as functional ceramics such as piezoelectrics, dielectrics, dielectric filters, semiconductors, and sensors. Recently, in order to improve the performance of functional ceramics, there has been a demand for the development of a technology that can efficiently produce perovskite raw powder that is easily sinterable and has a uniform particle size.

(Prior art and its problems) Conventionally, as a method for manufacturing perovskite raw material powder,
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 precipitation, dry soot, or calcination, making it difficult to sinter.

In addition, in the coprecipitation method, if the precipitate-forming ability of each component in the precipitate-forming solution is not the same, for example, the acid component is substantially 10
Although 0% precipitate is formed, substantially all of the other components may not be able to form precipitates, and it may be difficult to obtain the desired composition. In particular, Zn and Mg.

It was difficult to precipitate 100% of Co and Ni components.

(Objective of the Invention) The present invention eliminates the drawbacks of conventional production methods and provides a method that can efficiently produce fine perovskite raw material powder that is easy to sinter and has good uniformity.

(Technical Means for Solving the Problems) The present inventors have conducted intensive research to achieve the above object, and have arrived at the present invention.

The present invention provides a compound containing component A (wherein A represents one or more of oxygen-12-coordinated metal elements) and component B.
However, B is one or two of the oxygen hexacoordination metal elements.
A perovskite structure compound represented by the general formula ABO3 (A and B have the same meanings as above) and a raw material for its solid solution by calcining a mixture with a compound containing The present invention relates to a method for producing a perovskite raw material powder, which is characterized in that the mixture of the A component and the B component is calcined in the presence of a flux.

Examples of the oxygen 12-coordinating metal element of the A component of the -maximum ABO3 include Ba, Sr, Ca, and Pb.

These A components are appropriately selected depending on the characteristics or use, and one or two types of -m are selected. In addition, as the oxygen hexacoordination metal element of the B component, for example, Nb, Ta, Ti
, Zr, Zn, Mg, Ni, Co, W.

Examples include Fe, Sn, and the like. For dielectric filters, generally Nb, Ta, Ti, Zr, Zn, Mg, N
i is used. Also, for multilayer capacitors and actuators, Nb, Ti, Zr, Zn, M
g.

Ni, W, and Fe are used. As raw materials for component A and component B, compounds of the constituent elements, such as oxides, hydroxides, carbonates, nitrates, etc., are used.In carrying out the present invention, these compounds are prepared by a dry method. They may be used as a mixture, or as a precipitate obtained by a coprecipitation method or a multi-stage wet method.

The present invention is characterized in that the mixture of the A component and the B component is calcined in the presence of a flux. According to the present invention, grain growth is suppressed in the formation of a perovskite structure during calcination, and submicron 〉・uniform particles can be obtained.

The flux used in the present invention is a compound that does not decompose during calcination but melts. As a specific example of this, K, Na, B
a, sr: halides such as ca, especially KCJI, Na
Preferred examples include chlorides such as (J, BaCJI 5rCj2.CaCj122).

If the amount of flux used is too large, it will be uneconomical because it will take a lot of effort and time to remove the flux after calcination, and if the amount used is too small, sintering will be easier and the obtained Since the particles of the raw material powder become larger and the particle size distribution becomes wider, the amount of flux used is generally 10 to 80% by weight, preferably 20 to 70% by weight, based on the total weight of the flux and the mixture.
Weight%.

Also KCJ, Na CJ, Ba CJ 2.
Fluxing agents such as Sr Cjl 2゜c a c j 2 may be used alone or in combination of two or more types, but a fluxing agent containing the same element as component A constituting perovskite is used. It is desirable to do so.

If the calcination temperature is too low, the flux may not melt and the effect of the flux may not be sufficient, or even if melting occurs, the formation of the perovskite structure may be extremely slow. However, if it is too high, sublimation of the flux may occur. Therefore, the calcination temperature should be 650 to 1100°C, especially 700 to 100°C.
0°C is preferred.

It is necessary to sufficiently remove the flux from the perovskite raw material powder containing the calcined flux. For this purpose, after calcining, the material is crushed using a mulchizer or the like, and then washed with water or the like. The washing method is not particularly limited, but it is preferable to convert the material into qL using a line mill, line mixer, etc., and then wash it using a continuous rotary filter press because the flux can be efficiently removed.

(Example> The present invention will be explained below using Examples and Comparative Examples.

Example 1 Strontium carbonate (Sr Co3) 142.45 g
, zinc oxide (zn 0) 23.04g, niobium pentoxide (
Nb205) 75.25 g and titanium oxide (T i
Thoroughly mix 9.25 g of O2) in a ball mill, and add strontium chloride (src, Q2) as a fluxing agent to it.
・After adding 250 g of 6H20) and thoroughly mixing the mixture, it was calcined in an electric furnace at 800°C for 3 hours. After crushing this material with a crusher, adding water and emulsifying it thoroughly with a disperser, decantation was performed to remove water-soluble strontium chloride.
A composite perovskite of n1/3Nb2/3) 03-5r TiO3 was obtained.

An X-ray diffraction diagram and an electron micrograph (TEM photograph) of this powder are shown in FIGS. 1 and 2.

When this product was molded at 1.5 t/cd and fired at 1500°C, a product with 99% of the theoretical density was obtained.

The results are shown in Table 1.

Examples 2 to 3 In Example 1, the amount of strontium chloride as a flux was changed to 125 g (Example 2), and the calcination temperature was changed to 9.
A composite perovskite having the same composition as in Example 1 was produced by carrying out the same operation as in Example 1 except that the temperature was 00°C (Example 3).

The particle size of 50 particles was measured from a TEM photograph of the powder, and the average particle size was calculated. The powder is then molded and heated to 1500°C.
, and baked for 3 hours.

The results are shown in Table 1.

Comparative Examples 1-2 Strontium carbonate 142.45g, zinc oxide 23.0g
4g, niobium pentoxide 75.25g, titanium oxide 9.25g
g were thoroughly mixed in a ball mill, and then calcined in an electric furnace at 800°C (Comparative Example 1) and 1300°C (Comparative Example 2) for 3 hours to produce a composite perovskite having the same composition as Example 1.

The X-ray diffraction pattern of this product is shown in FIG. 3 and FIG. 4, respectively, and the TEM photograph of the powder calcined at 1300° C. is shown in FIG. 5.

Further, these powders were fired at 1550°C to obtain a sintered body. The density is shown in Table 1.

Example 4 Barium carbonate (BaCo3) 134.2 g, zinc oxide 12.9 g, tantalum pentoxide (TazOs) i.

0.2 g and 27 g of magnesium oxide (MgO) were thoroughly mixed in a ball mill. Barium chloride (Ba C!J 2 ・2H20) 2 which is a fluxing agent is further added to the mixture.
50 g was added and thoroughly mixed and calcined in an electric furnace at 900° C. for 3 hours.

After pulverizing this material with a soaker, water was added thereto, and the mixture was thoroughly pulverized and emulsified using a homogenizer, and barium chloride was removed by decantation. After that, p passed,
Dry and prepare B a (Z n 1/3 T a 2
/ 3) 03-B a (M!J 1/3 T a
2/3) O3(7) composite perovskite was obtained.

The X-ray diffraction pattern and electron microscope of this powder were measured. X
A line diffraction diagram is shown in FIG.

Also, when this material is fired at 1550℃, the theoretical density is 98
% was obtained.

Comparative Example 3 The same method as in Example 4 was repeated except that barium chloride as a fluxing agent was not added.

Also, when this material is fired at 1570℃, the theoretical density is 9.
It was 3%.

Example 5 Lead oxide (pb 0) 164.24g, zinc oxide 3.18g
g, iron oxide (Fe203) 2&18 g, tungsten oxide (WO3) 20.47 g and niobium pentoxide 33.
93 g were thoroughly mixed in a ball mill. 250 g of sodium chloride as a flux was further added to the mixture, and the mixture was thoroughly mixed and calcined in an electric furnace at 600° C. for 3 hours.

After crushing this thing with a pickler, do you use water? After adding and sufficiently emulsifying with a disperser, 1-lium chloride was removed by decantation.

Thereafter, it was filtered and dried to give 0.16 P b (Z n17
3N b2/3)03-0.36Pb(Fe2/3W1
/3) 03-o, 48Pb (F e 1 /2 N b
1/2) 03 composite perovskite was obtained.

The X-ray diffraction pattern and electron microscope of this powder were measured. X
The line diffraction pattern is shown in FIG. 7, and the 'T' EM photograph is shown in FIG. 8.

Also, when this material is fired at 830°C, the theoretical density is 98.
5% was obtained.

Example 6 Lead oxide (Pb 0) 173.15g, titanium oxide 23.
14g, 23.91g of zirconium oxide (Zr 02)
, 3.91 g of magnesium chloride (MQ O) and 25.79 g of niobium pentoxide were thoroughly mixed in a ball mill. Add 25% sodium chloride to the mixture as a fluxing agent.
0g was added and thoroughly mixed and calcined in an electric furnace at 700°C for 3 hours.

After pulverizing this material using a crusher, water was added and the mixture was thoroughly emulsified using a disperser, and sodium chloride was removed by decantation. After that, it was filtered and dried to give 0.375Pb (Mg1/3Nb2/3)0 -0.3
A composite perovskite of 75PbTi 03-0.25Pb ZrO3 was obtained.

Also, this one is 1. When molded at Ot/aj and fired at 1100°C, a product with a theoretical density of 99.5% was obtained.

Comparative Examples 4-5 Lead carbonate 164.24g, zinc oxide 3.18g, iron oxide 2
18g of a, 20.47g of tungsten oxide, and 33.93g of niobium pentoxide were thoroughly mixed in a ball mill, and then calcined in an electric furnace at 660°C (Comparative Example 4) and 700°C (Comparative Example 5) for 3 hours. A composite perovskite having the same composition as Example 10 was produced.

The X-ray diffraction diagrams of this material are shown in Figures 9 and 10, respectively.
Furthermore, a TEM photograph of the powder fired at 660° C. is shown in FIG.

Further, these powders were fired at 850°C to obtain a sintered body.

The density is shown in Table 1.

Table 1 Percentages relative to theoretical density Examples 7 to 11 Products having the compositions shown in Table 2 were produced in the same manner as in Example 4 except that the proportions of each raw material used were changed.

When I observed these TEM photos, it was found that 0.1 to 0.3
Uniform particles of μm were obtained.

(Effects of the Invention) According to the present invention, when producing perovskite raw powder, the raw material powder of perovskite is calcined in the presence of a flux, which reproduces the easily sinterable perovskite raw powder with fine particles (submicrons) and a narrow particle size distribution. It can be easily manufactured.

[Brief explanation of the drawing]

FIG. 2, FIG. 5, FIG. 8, and FIG. 11 replace drawings showing the particle morphology of perovskite raw material powders obtained in Example 1, Comparative Example 2, Example 5, and Comparative Example 4 of the present invention. Transmission electron micrographs (Figures 2 and 5 are at a magnification of 30
(Figures 8 and 11 are magnifications of 15,000x)
FIG. 1, FIG. 3, FIG. 4, FIG. 6, FIG. 7, FIG. 9, and FIG. 10 respectively show Example 1, Comparative Example 1, Comparative Example 2, and Example of the present invention. 4. It is an X-ray diffraction diagram of perovskite raw material powders obtained in Example 5, Comparative Example 4, and Comparative Example 5. Patent Applicant: Ube Industries, Ltd. No. 1 Fig. #r angle (2θ) Fig. 2 Fig. 3 Rotation #r angle (2θ) Fig. 4 Rotation tltIfl (2θ) Fig. 5 Fig. 6 Diffraction angle ( 20] Figure 7 Figure 8 'IS9 Figure inside the diffraction (2e) Figure 10 Inside the diffraction ζ2θ) Figure 11

Claims (1)

[Claims] A compound containing component A (where A represents one or more types of oxygen-12-coordinated metal elements) and B component (however, B represents one or more types of oxygen-6-coordinated metal elements). ) is calcined to form a compound of the general formula A.
BO_3 (However, A and B have the same meanings as above) In a method for producing a raw material powder of a perovskite-type structural compound and its solid solution (hereinafter referred to as perovskite), a mixture of the A component and the B component. A method for producing perovskite raw material powder, which is characterized by calcining in the presence of a flux.