JPH10236824A - Titania-zirconia multiple oxide fine powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a TiO2 -ZrO2 multiple oxide fine powder of uniform composition useful as the intermediate material of a dielectric, etc., and having a large specific surface. SOLUTION: This fine powder consists of the fine grain of Tix Zr1-x O2 (0<x<1) as a solid soln. of TiO2 -ZrO2 and has >=15m<2> /g specific surface. The fine powder is produced by adding alcohol or alcohol, water and a carboxylic acid to the soluble salts of titanium and zirconium which are dissolved, heating the soln. obtained to form a gel, heat-treating the gel at 400-900 deg.C and then crushing the gel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a uniform and fine titania (TiO ₂ ) -zirconia (intermediate material such as barium zirconate titanate or lead zirconate titanate) useful as a high performance dielectric material. The present invention relates to a ZrO ₂ ) -based composite oxide fine powder and a method for producing the same.

[0002]

Including Ba salts of zirconate titanate _{(BaTi x Zr 1-x O} 3) and lead salt _{(PbTi x Zr 1-x O} 3) is known as the Related Art Dielectric electronic ceramics. As a method for producing these compounds, in the case of a lead salt, a method disclosed in
In -243565, PbO and Ti _x Zr _{1 -x} O ₂ are mixed, heated and reacted, and then pulverized to a powder. In this patent, Ti _x Zr _{1 -x} O ₂ is prepared by adding ammonia to a mixed solution of an aqueous solution of titanium tetrachloride and zirconyl nitrate to form a slurry, filtering and drying the slurry, and then drying the slurry.
It is manufactured by heat treatment at ℃, cooling and pulverization. In addition, a method of mixing TiO ₂ and ZrO ₂ powders and performing heat treatment at a high temperature is also known.

[0003]

[SUMMARY OF THE INVENTION] TiO ₂ and it is difficult to form a composite oxide TiO ₂ and ZrO ₂ are uniformly dissolved in the method of using a mixed powder of ZrO _2, also the heat treatment temperature for equalizing Also, high temperature is required, so that the particles of the composite oxide to be formed grow, so that fine particles desirable as an intermediate material cannot be obtained. The method of this point above patents TiO ₂ and ZrO ₂ is somewhat enough solid solution, also is its particle size is also 0.05 to 0.1 [mu] m, are fairly fine can not be obtained. However, the heat treatment temperature for obtaining a uniform crystal is still 900 to 1100.
Since the temperature is as high as ° C., the particles are not sufficiently fine, and the specific surface area derived from the surface shape and the like of the particles is not sufficiently large. The present invention relates to a TiO useful as an intermediate material of a ceramic dielectric.
It is an object of the present invention to provide a composite oxide fine powder in which ₂ and ZrO _{2 form a} solid solution, have a small particle size and a large specific surface area.

[0004]

SUMMARY OF THE INVENTION The present invention has been developed as a result of intensive research to solve the above-mentioned problems, and its basic structure is as follows. 1) Ti _x Zr _1-x O _{2 in which} TiO ₂ and ZrO _{2 form a} solid solution
(0 <x <1) having a specific surface area of 15
A TiO ₂ -ZrO ₂ -based composite oxide fine powder having a m ² / g or more. 2) Alcohol or alcohol, water and carboxylic acid are added to and dissolved in a soluble salt of titanium and zirconium, and the resulting solution is heated to form a gel.
TiO ₂ -Zr characterized by heat treatment at 900 ° C.
A method for producing an O ₂ -based composite oxide fine powder.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The composite oxide fine powder of the present invention is Ti
O ₂ and ZrO ₂ are uniformly dissolved to form Ti _x Zr _1-x O ₂ . The formation of this compound can be confirmed by the fact that a single kind of peak is obtained with an X-ray diffractometer. Its crystal structure is generally of the anatase type.
According to X-ray diffraction, for example, when TiO ₂ is excessive, Ti
Only the peak of the crystal structure of O ₂ shifted to the lower angle side due to the solid solution of ZrO ₂ appears, indicating that it is a single compound (solid solution).

In the composite Ti _x Zr _{1 -x} O ₂ of the present invention, x is a value larger than 0 and smaller than 1, preferably 0.6 to 0.9, more preferably 0.65 to 0.
85. The composite oxide powder of the present invention is formed of fine particles and has a particle surface shape having a large specific surface area. Specifically, it has a specific surface area of 15 m ² / g or more. The upper limit is about 80 m ² / g due to restrictions on the production method. The average size of the particles is preferably 50 nm or less. Because of such a fine and large specific surface area,
BaO The composite oxide, BaTi _x of high reactivity, and uniform composition is reacted with PbO like Zr _1-x O ₃
Etc. are obtained.

Next, the manufacturing method will be described. As a raw material, a soluble salt of a titanium salt and a zirconium salt is used.
As the titanium salt, titanium tetrachloride, titanium sulfate, titanium alkoxide is preferable, and as the zirconium salt, zirconium oxynitrate, zirconium oxychloride,
Zirconium tetrachloride is preferred. These titanium salts and zirconium salts are mixed, and alcohol and carboxylic acid are added thereto. Further, water can be further added.
In this case, it is considered that alcohol or alcohol containing water becomes a solvent for dissolving the soluble salt in the solution, and carboxylic acid acts with the soluble salt to form a compound such as a complex. The order of adding the alcohol and the carboxylic acid to the soluble salt is not particularly limited, and the salt may be added to the alcohol and dissolved, and then the carboxylic acid may be added, or the soluble salt may be added to a mixed solution of the alcohol and the carboxylic acid. . The mixing ratio of the titanium salt and the zirconium salt depends on the desired T
i _x Zr may be determined in accordance with the _1-x O ₃ of x.

As the alcohol, a monohydric alcohol or a polyhydric alcohol can be used, and methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, 1,3-propanediol, 1,2
-Propanediol, 1,4-butanediol, 1,3
-Butanediol, 1,2-butanediol, 2,3-
Butanediol is preferred. These can be used alone or in combination of two or more. As the carboxylic acid, it is preferable to use at least one of citric acid, malic acid, tartaric acid, lactic acid, glycolic acid, tricarballylic acid, succinic acid, oxalic acid, maleic acid, malonic acid, acrylic acid and acetic acid.

Regarding the addition ratio of each raw material, the molar ratio of the solvent to the soluble salt is preferably 1: 1 to 100: 1.
When the ratio of the solvent to the soluble salt is less than 1, the amount of the solvent becomes too small to completely dissolve the soluble salt. On the other hand, 10
Exceeding 0 is not preferable because the polymerization reaction takes a long time. The ratio between the soluble salt and the carboxylic acid is 1: 1:
0.1 to 1:10 is preferred. If this ratio is less than 0.1, a sufficient effect cannot be obtained, and the soluble salt does not complex. On the other hand, if it exceeds 10, the reaction product such as a complex may precipitate as a salt, which is not preferable. When water is added to the mixed solvent, the content is preferably 50 mol% or less. The reason is that when the amount of water is large, the polymerization reaction is a dehydration-condensation polymerization reaction, so that the progress of the polymerization reaction is hindered.

[0010] The polymerization reaction is carried out by heating the mixed solution with a mantle heater, a hot plate or the like. The reaction temperature varies depending on the reaction time,
Is suitable, and preferably 2 to 10 at 120 to 160 ° C.
Time. After completion of the reaction, the unreacted solvent is removed by heating and concentrated to obtain a transparent gel. Next, the obtained transparent gel is heat-treated. An ordinary electric furnace can be used as the heat treatment apparatus, and the treatment atmosphere may be an oxidizing atmosphere capable of removing organic components, and may be air, oxygen-enriched air, or the like. The processing temperature is preferably from 400 ° C to 900 ° C. If the temperature is lower than 400 ° C., the organic component remains in the product, which is not preferable. If the temperature is higher than 900 ° C., the product particles are sintered and grow as described above, and the specific surface area increases. The heating rate should be as fast as possible.
0-100 degreeC / min is preferable. After calcination, the product, which is a lump, is made uniform using a suitable pulverizer to obtain a product.

The reason why a uniform and fine composite oxide can be produced by the present invention is not clear, but it is necessary to form a gel which is homogenized at the stage of forming a complex of a soluble salt, etc. It is considered that the oxide is formed while maintaining the property.

[0012]

The present invention will be described more specifically with reference to the following examples. FIG. 1 shows a reaction vessel with a reflux condenser used for the reaction of the example. In the figure, reference numeral 1 denotes a reaction tank filled with a mixed solution 2 and a reflux condenser 3 is provided therein. 4 is a stirrer, 5 is a thermometer,
6 is a device for heating the reaction tank.

Example 1 2 mol (384 g) of ethylene glycol was placed in a glass flask equipped with a reflux condenser as shown in FIG. 1, and 0.5 mol (31 g) of anhydrous citric acid was dissolved therein. , 0.8 mol (152 g) of titanium tetrachloride and 0.2 mol of zirconium oxychloride octahydrate
Add mole (65 g) and heat to about 60 ° C. to completely dissolve. This is maintained at 120 ° C. by a mantle heater to polymerize ethylene glycol and citric acid. About 6
After holding for a period of time, the solution was transferred to a beaker and
By maintaining at 60 ° C., unreacted ethylene glycol is evaporated to obtain a transparent gel. After holding the solution for about 2 hours and reducing the liquid volume to about 1/5, the organic component is decomposed in a beaker in an electric furnace at 350 ° C. in an air atmosphere to be taken out as a solid. The solid was sufficiently pulverized in an agate mortar and then kept in an electric furnace at 700 ° C. for 2 hours in an air atmosphere to completely decompose organic components to obtain a desired fine powder.

The specific surface area of the fine powder measured by the BET method was 25 m ² / g. FIG. 2 shows the results of observation with a scanning electron microscope (SEM). It is clear from the figure that the powder has a very fine primary particle having an average particle diameter of 50 nm. FIG. 3 shows the identification of the powder by an X-ray diffraction apparatus. From the figure, only a peak in which the anatase type titanium oxide was shifted to the lower angle side was obtained from this powder, which indicates that the powder was uniform.

Example 2 A desired fine powder was obtained in the same manner as in Example 1 except that malic acid was used for citric acid and isopropanol was used for ethylene glycol. When the specific surface area of this fine powder was measured by the BET method, it was 60 m ² / g. Scanning electron microscope (SE
M), the average particle size of the primary particles was 25 nm.
It became clear that it was very fine. Further, when the powder was identified by an X-ray diffractometer, only a peak in which anatase type titanium oxide was shifted to a lower angle side was obtained, indicating that the powder was homogenized.

Comparative Example 1 Titanium oxide (9 manufactured by Wako Pure Chemical Industries, Ltd.)
9.9%) and 73.2 g of zirconium oxide (99.9%, manufactured by Wako Pure Chemical Industries) were stirred for 2 hours in a ball mill using zirconia beads, and then sufficiently filtered and dried using agate mortar. After crushing, 700 in air atmosphere
It was kept in an electric furnace at a temperature of 10 ° C. for 10 hours to obtain a target powder. The specific surface area of this fine powder was measured by the BET method and found to be 20 m ² / g. From the result of observation with a scanning electron microscope (SEM), the powder had an average primary particle diameter of 60 n.
It was found that the particle size was as fine as m. However X
When the powder was identified by a line diffraction apparatus, only two peaks of anatase type titanium oxide and zirconium oxide were observed. This indicates that the powder is merely a mixture.

(Comparative Example 2) The conditions of the heat treatment were 1400 ° C.
Except for 10 hours, the same procedure as in Comparative Example 1 was performed to obtain a target powder. When the powder was identified by an X-ray diffractometer, only a peak in which anatase-type titanium oxide was shifted to a lower angle side was obtained as in Example 1, indicating that the powder was homogenized. , The specific surface area of this fine powder
When measured by the ET method, it was 10 m ² / g. From the result of observation with a scanning electron microscope (SEM), the powder was found to be 1 m ² / g.
The average particle diameter of the secondary particles was very large at 900 nm, and it was clear that the particles were sintered.

[0018]

According to the present invention, a uniform and fine specific surface area of 1
A TiO ₂ -ZrO ₂ -based composite oxide of 5 m ² / g or more is obtained. By using this and reacting with BaO or the like by a high-temperature solid-phase method, barium zirconate titanate or the like having a fine and uniform composition can be obtained at a lower temperature than conventional.

[Brief description of the drawings]

FIG. 1 shows a reaction vessel with a reflux condenser used for the reaction in the present invention.

FIG. 2 is a scanning electron micrograph (magnification: 50,000) of the TiO ₂ -ZrO ₂ -based composite oxide obtained in Example 1.

FIG. 3 is an X-ray diffraction diagram of the TiO ₂ -ZrO ₂ -based composite oxide and TiO ₂ (anatase) of the present invention.

[Explanation of symbols]

 Reference Signs List 1 reaction tank 2 mixed solution 3 reflux cooler 4 stirrer 5 thermometer 6 heating device

Claims (8)

[Claims] 1. Ti _x in which titania and zirconia form a solid solution
A titania-zirconia composite oxide fine powder comprising fine particles of Zr _1-x O ₂ (0 <x <1) and having a specific surface area of 15 m ² / g or more. 2. The value of x is 0.6 to 0.9.
The composite oxide fine powder as described above. 3. The composite oxide fine powder according to claim 1, wherein the fine particles have an average particle diameter of 50 nm or less. 4. Dissolving a soluble salt of titanium and zirconium by adding alcohol or alcohol, water and carboxylic acid, heating the resulting solution to form a gel, and subjecting the gel to heat treatment at 400 to 900 ° C. A method for producing a titania-zirconia-based composite oxide fine powder, which is characterized in that: 5. The method according to claim 1, wherein the alcohol is methanol, ethanol,
Propanol, isopropanol, butanol, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol The method for producing a composite oxide fine powder according to claim 4, which is at least one of the following. 6. The method according to claim 4, wherein the soluble salt of titanium is at least one of titanium tetrachloride, titanium sulfate and titanium alkoxide. 7. The method for producing a composite oxide fine powder according to claim 4, wherein the soluble salt of zirconium is at least one of zirconium oxynitrate, zirconium oxychloride and zirconium tetrachloride. 8. The method according to claim 1, wherein the carboxylic acid is at least one of citric acid, malic acid, tartaric acid, lactic acid, glycolic acid, tricarballylic acid, succinic acid, oxalic acid, maleic acid, malonic acid, acrylic acid and acetic acid. 8. The method for producing a composite oxide fine powder according to 4 to 7.