JPH06227816A - Perovskite type precursor powder and its production - Google Patents

Abstract

PURPOSE:To provide perovskite type precursor powder burnable at a low temperature. CONSTITUTION:This perovskite type precursor powder comprises titanium oxide powder having the surface containing one or more, selected from the group consisting of barium, calcium, strontium and lead salts and double salts thereof and existing therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perovskite type precursor powder used in the field of electronics such as dielectric ceramics, piezoelectric ceramics, pyroelectric ceramics, resistor ceramics and semiconductor ceramics.

[0002]

2. Description of the Related Art Perovskite type oxides such as barium titanate are mixed with barium carbonate powder and titanium dioxide powder and baked at a high temperature to carry out a solid phase reaction, followed by pulverization. It is manufactured by going through.

[0003]

By the way, in the above-mentioned manufacturing method, since the solid-phase reaction requires a temperature of about 1100 ° C., the cost increases accordingly. Also, since it is fired at a high temperature, if the oxide is of a complex type,
There is also a problem that the composition tends to vary, that is, it is difficult to obtain the composition as designed because the evaporation degree of each substance is different.

Further, since the reaction is carried out at a high temperature, there is a problem that grain growth easily occurs. Therefore, the object of the present invention is to
An object of the present invention is to provide a perovskite type precursor powder capable of low temperature firing.

[0005]

The above-mentioned object of the present invention is that one or more selected from the group of barium salts, calcium salts, strontium salts, lead salts, and complex salts thereof are titanium oxide powders. It is achieved by a perovskite type precursor powder characterized by being interposed on the surface.

Further, one or more salts selected from the group consisting of barium salt, calcium salt, strontium salt, lead salt, and complex salts thereof and titanium oxide powder are interposed in the solution, and then deliquoring treatment is performed. To produce a perovskite-type precursor powder in which one or more selected from the group consisting of barium salt, calcium salt, strontium salt, lead salt, and complex salts thereof are present on the surface of titanium oxide powder. This is achieved by a method for producing a perovskite type precursor powder, which is characterized in that

From the perovskite type precursor powder according to the present invention, a perovskite type oxide can be obtained by firing at a low temperature such as 600 ° C.,
The cost can be reduced. Further, not only can the firing cost be reduced, but when it is used as an electronic component material such as a multilayer capacitor material, the amount of palladium in the silver-palladium alloy used as the internal electrode can be reduced or eliminated altogether. From the viewpoint, cost reduction can be effectively achieved.

The titanium oxide powder used in the present invention preferably has a particle size of 40 nm or less. That is, if the particle diameter of the titanium oxide powder exceeds 40 nm and becomes too large, the firing temperature tends to be high, and the reaction time (firing time) tends to be long because of the single phase. is there. Further, it is sufficient that one or more selected from the group of barium salt, calcium salt, strontium salt, lead salt, and their complex salts are present on the surface of the titanium oxide powder, which is a physical property. A form such as adsorption is common, but the form is not limited to this. Alternatively, a means such as coating may be used.

The present invention will be described in detail below. As the titanium oxide used in the present invention, titanium oxide such as TiO and TiO ₂ is used. Further, as long as the particle diameter is 40 nm or less, it may have any shape such as spherical, granular or acicular, but is preferably spherical or granular.
Further, it may be obtained by any manufacturing method.

As the barium salt, for example, barium hydroxide, barium acetate, barium formate, barium chloride, barium nitrate or the like can be used, and as the calcium salt, for example, calcium acetate, calcium chloride, calcium nitrate or the like can be used. As the strontium salt, for example, strontium acetate, strontium chloride, strontium nitrate or the like can be used, and
As the lead salt, for example, lead acetate, lead chloride, lead nitrate or the like can be used.

Since these salts are water-soluble, there are no special conditions regarding the size and shape of the powder. Then, the titanium oxide powder is added to a solution in which the salt as described above is dissolved at a predetermined concentration, and the mixture is sufficiently stirred and mixed, and then dried to remove water, thereby removing barium salt on the surface. Titanium oxide powder adhered almost uniformly is obtained. Incidentally, by adding barium salt or the like to an aqueous solution containing titanium oxide, thoroughly stirring and mixing, and then drying to remove water, titanium oxide having barium salt or the like deposited almost uniformly on the surface is also added. A powder is obtained.

At this time, it is preferable to adjust the pH of the solution to 1 to 5, preferably 2 to 4. That is, when the pH is adjusted to be within the above range, the dispersibility of the titanium oxide powder is improved, and the barium salt or the like is easily attached to the surface almost uniformly. Next, the aqueous solution obtained as described above is dried,
This drying is preferably performed by spray drying.
That is, the dehydration (drying) process is performed by spraying the aqueous solution from the nozzle under a heated atmosphere. In this spray drying, it is preferable to take care so that the particles do not aggregate. Since aggregation is greatly affected by the temperature under spraying, it is preferable to spray under an atmosphere heated to a temperature of 150 to 250 ° C, for example.
In particular, spraying in the presence of a flame is preferable because fusion of particles does not occur. Then, when spray drying is performed in this manner, there is no agglomeration and 40 nm
A spherical powder of the following size is obtained.

A desired electronic component is obtained by forming a titanium oxide powder having a barium salt or the like substantially uniformly attached to the surface obtained by spray drying into a desired shape and firing the powder in an oxidizing atmosphere. To be This firing is about 6
It is possible at temperatures of 00 ° C. and is carried out at temperatures of 600-1050 ° C. Of course, it is not limited to this. However, if it is too high, the composition may deviate from the design value or grain growth may occur, which is not preferable.

The present invention will be described below with reference to specific examples.

[0015]

【Example】

[Example 1] 2000 m of 0.5 M barium nitrate aqueous solution
79.87 titanium dioxide powder having an average particle size of 20 nm
g, thoroughly mixed and dispersed, and nitric acid was added with stirring to adjust the pH to about 3.

After adjusting the pH, the solution was refluxed for 2 hours to uniformly disperse the barium salt around the titanium dioxide powder and then dried by means of spray drying to coat the surface of the titanium dioxide powder with the barium salt. (Adhesion)
222 g of the powder thus obtained (perovskite-type barium titanate precursor powder according to the present invention) was obtained. The powder thus obtained was fired at 600 ° C. for 1 hour in an oxidizing atmosphere.

When the fired product was examined by an X-ray diffraction analyzer, it was found that it had a BaTiO ₃ single phase. That is, barium titanate was obtained by firing at a low temperature of 600 ° C. Example 2 79.87 g of titanium dioxide powder having an average particle size of 20 nm was added to 1000 ml of 1.0 M lead nitrate aqueous solution, mixed and dispersed sufficiently, and nitric acid was added with stirring to bring the pH to about 3. It was adjusted.

After adjusting the pH, the solution was refluxed for 2 hours to uniformly disperse the lead salt around the titanium dioxide powder and then dried by means of spray drying to coat the surface of the titanium dioxide powder with the lead salt. 281 g of powder (adhered) (perovskite type lead titanate precursor powder of the present invention) was obtained. The powder thus obtained was fired at 600 ° C. for 1 hour in an oxidizing atmosphere.

When the fired product was examined by an X-ray diffraction analyzer, it was found that it had a PbTiO ₃ single phase. That is, lead titanate was obtained by firing at a low temperature of 600 ° C. [Example 3] 1000 m of 0.4 M barium nitrate aqueous solution
79 ml of titanium dioxide powder having an average particle size of 20 nm was added to 2000 ml of a mixed aqueous solution prepared by adding 500 ml of 0.4 M strontium nitrate aqueous solution and 500 ml of 0.8 M calcium nitrate aqueous solution to 1 and thoroughly mixed and dispersed. Then, nitric acid was added with stirring to adjust the pH to about 3.

After adjusting the pH, the solution was refluxed for 2 hours to uniformly disperse the complex salt of barium salt, strontium salt and calcium salt around the titanium dioxide powder, and then dried by means of spray drying. 209 g of powder obtained by coating (adhering) the surface of titanium dioxide powder with a complex salt (perovskite-type calcium titanate / strontium / barium precursor powder according to the present invention)
Got

About the powder thus obtained, 60
Firing was carried out at 0 ° C. for 1 hour in an oxidizing atmosphere. This grill
The product was examined with an X-ray diffraction analyzer.
R, this is Ba _0.4Sr_0.2Ca_0.4TiO₃Into a single phase
It turns out that it has become. That is, such as 600 ℃
Calcium strontium titanate by low temperature firing
・ Barium was obtained.

[0022]

According to the present invention, a perovskite type oxide having a composition as designed can be obtained at low cost.

Front Page Continuation (72) Inventor Yoichi Nishimoto 5310 Sangejiri, Kumagaya City, Saitama Prefecture Chichibu Cement Co., Ltd. Fine Ceramics Division

Claims (3)

[Claims] 1. A titanium oxide powder comprising one or more selected from the group consisting of barium salt, calcium salt, strontium salt, lead salt, and complex salts thereof. Perovskite type precursor powder. 2. The titanium oxide powder has a particle size of 40 nm.
The perovskite type precursor powder according to claim 1, characterized in that: 3. A solution containing at least one salt selected from the group consisting of barium salt, calcium salt, strontium salt, lead salt, and complex salts thereof, and titanium oxide powder, followed by deliquoring treatment. To produce a perovskite-type precursor powder in which one or more selected from the group consisting of barium salt, calcium salt, strontium salt, lead salt, and complex salts thereof are present on the surface of titanium oxide powder. A method for producing a perovskite-type precursor powder, comprising: