JPH06321630A - Composition for ceramic dielectric - Google Patents

Abstract

PURPOSE:To obtain a compsn. giving a ceramic dielectric having a high relative dielectric constant, high insulation resistance and low dielectric tangent as well as high sintered density and excellent in electrical characteristics by firing at a low temp. CONSTITUTION:This compsn. is based on a perovskite compd. contg. at least one kind of element selected from among Mg, Ca, Sr, Ba, Pb and rare earth elements and at least one kind of element selected among Ti, Zr, Hf and Sn. The perovskite compd. consists of a perovskite compd. obtd. by a calcining method and 0.5-50wt.% perovskite compd. obtd. by a wet method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic dielectric composition. The present invention relates to a composition having a density, a high relative dielectric constant, a high insulation resistance, a low dielectric loss tangent, and the like, and providing a ceramic dielectric having excellent electrical characteristics.

[0002]

2. Description of the Related Art Generally, a perovskite compound means a compound having a crystal structure similar to that of calcium titanate ore (perovskite).
By sintering, dielectric ceramics having dielectric, piezoelectric and semiconducting properties can be obtained, and these are recently used as capacitors, radio wave filters, ignition elements, thermistors, etc. Used in large amounts in electronic devices.

Conventionally, perovskite compounds are generally prepared by mixing carbonates or oxides such as Mg, Ca, Sr, Ba and Pb with oxides such as Ti, Zr, Hf and Sn.
It is manufactured by calcining at a temperature of about 1000 ° C., then wet pulverizing, filtering and drying. However, when a perovskite compound is produced by such a calcination method, since the perovskite compound is united during the calcination, it is difficult to reduce the particle size to 1 μm or less even with wet pulverization. The average particle size is 1 μm or more, and the shape is crushed. Therefore, when the perovskite compound particles are formed by the calcination method and sintered to form a dielectric, they have poor sinterability.For example, if barium metatitanate particles are taken as an example, this is To make a sintered body, it is usually about 1400
Calcination at a high temperature of ℃ or more is required, and the particle size of about 5 μm to several tens μ
Crystals grow to about m, and a sintered body composed of fine particles cannot be obtained. Thus, the sintered body of barium titanate by the calcination method, the sintered particles have a large particle size,
It is said to be optimal as a dielectric for capacitors.
There is a large gap between the particle size of about 5 to 1 μm.

In particular, a laminated ceramic capacitor is integrally formed by alternately laminating a ceramic dielectric made of a sintered body of a perovskite compound and an electrode metal, and a typical ceramic dielectric is barium metatitanate ( A sintered body of BaTiO ₃ ) is used. But,
As described above, since BaTiO ₃ obtained by the calcination method has a large grain size, it is necessary to increase the degree of sintering to obtain a dense sintered body.
It is necessary to fire at a high temperature of 400 ° C or higher, while Ba is used in the production of multilayer ceramic capacitors.
Since a step of heating and firing TiO ₃ together with a metal for the internal electrode is included, conventionally, an expensive noble metal electrode system having a high melting point such as platinum or palladium has to be used as the internal electrode of the multilayer ceramic capacitor. I don't get it.

Therefore, the low-melting glass composition powder and the perovskite compound particles are mixed so that a metal material having a relatively low melting point such as silver and an inexpensive metal material can be used as an internal electrode of the laminated ceramic capacitor. However, a method of sintering at a relatively low temperature has been proposed (for example, KR Chowdary et al., Ferroelectrics, 1981 , V
ol. 37, pp. 689-692, JP-A-54-66450, etc.) and the low dielectric constant of the low melting point glass composition, the resulting ceramic dielectric also has a low relative dielectric constant.

In the production of ceramic dielectrics by firing the perovskite compound, sintering aids such as cadmium oxide, lead oxide, bismuth oxide, silica and alumina are often used in combination. The agent also causes a decrease in the relative dielectric constant of the obtained ceramic dielectric.

On the other hand, the production of a perovskite compound by a wet method is also described, for example, as a typical example, Journal of Industrial Chemistry, No. 71.
Volume 1, pp. 114-118 (1968) and functional materials 1
It is already known as described in December 982, pp. 1-8, etc., and this wet method includes a hydrothermal synthesis method, an alkoxide method and a coprecipitation method. According to such a wet method, a fine perovskite compound having an average particle size of 1 μm or less, preferably 0.5 μm or less can be obtained, and such a fine perovskite compound is calcined at a relatively low temperature. It is also known to be able to give a body.
However, since the perovskite compound by the wet method is generally expensive, it may be difficult to use it depending on the application, and there is a demand for a low-cost and highly sinterable ceramic dielectric composition. ing.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The inventors of the present invention have earnestly studied in order to solve the above-mentioned problems in the production of ceramic dielectrics by firing a perovskite compound, and as a result, the perovskite compound by the calcination method and the wet method were used. A composition containing a perovskite compound as a main component gives an extremely dense sintered body by firing at low temperature, and
It was found that the ceramic dielectric made of such a sintered body has a high relative dielectric constant and excellent electrical characteristics, and further,
According to such a composition, for example, it is possible to use a metal having a low melting point as an internal electrode material, which can reduce the electrode manufacturing cost of the laminated ceramic capacitor, has a high relative dielectric constant, and is excellent in electrical characteristics. The present invention has been accomplished by finding that a laminated ceramic capacitor can be easily manufactured.

Therefore, the present invention is excellent in sinterability by firing at a low temperature, and has a high sintering density, a high relative dielectric constant and a high firing rate by firing at a temperature in the range of 1100 to 1300 ° C. It is an object of the present invention to provide a composition that has a ceramic dielectric having excellent insulation characteristics, low dielectric loss tangent and the like and excellent electrical characteristics.

[0010]

The composition for ceramic dielectric according to the present invention comprises (a) Mg, Ca, Sr, Ba, Pb.
And at least one selected from the group A consisting of rare earth elements
A composition containing, as a main component, a perovskite compound containing one element and (b) at least one element selected from the B group consisting of Ti, Zr, Hf, and Sn,
The perovskite compound is a perovskite compound prepared by the calcining method and a perovskite compound prepared by the wet method 0.5 to 5
It is characterized by comprising 0% by weight.

The particles of the perovskite compound are produced by the calcination method or the wet method, as described above.
As described above, the calcination method includes Mg, Ca, Sr, Ba,
Carbonate or oxide of at least one element selected from the group A consisting of Pb and rare earth elements, and Ti, Zr, Hf
And an oxide of at least one element selected from the group B consisting of Sn, calcined at a temperature of about 1000 ° C., wet pulverized, filtered and dried to produce a perovskite compound. . The perovskite compound particles obtained by the calcination method usually have an average particle size of 1 μm or more.

As the manufacturing method by the wet method, as described above, the hydrothermal synthesis method, the metal alkoxide method, the coprecipitation method and the like are known. The hydrothermal synthesis method includes a hydroxide of at least one element selected from the group A (hereinafter, referred to as A hydroxide) and a hydroxide of at least one element selected from the group B (hereinafter, It can be obtained by preparing a hydroxide mixture with B hydroxide) and subjecting this to a hydrothermal treatment.

The hydroxide mixture can be prepared, for example, by mixing A hydroxide and B hydroxide as a simple method. As another method, for example, a mixture of a salt of the group A element and a salt of the group B element may be reacted with an alkali, and a hydroxide (or salt) of the group A element and a salt of the group B element ( Alternatively, the mixture may be reacted with an alkali. Furthermore, as another method, a hydroxide (or alkoxide) of the group A element may be reacted with an alkoxide (or hydroxide) of the group B element, or an alkoxide of the group A element and an alkoxide of the group B element. May be hydrolyzed.

Then, the hydroxide mixture as described above is subjected to a hydrothermal treatment to obtain fine particles having a particle diameter of 1 μm or less, which are composed of a perovskite compound and can be preferably used in the present invention.

Hydrothermal treatment refers to the industrial chemistry magazine cited above and Bulletin of the Chemical Society of Japan, 51
(6), 1739-1742 (1978) and the like, as already known, refers to heat treatment in an aqueous medium,
In the present invention, the hydrothermal treatment may be carried out by adding an alkali to the hydroxide mixture at a temperature below the critical temperature of the aqueous medium, if necessary, and then heating the originally alkaline hydroxide mixture. Preferably the hydrothermal treatment temperature is 100 ° C
To below the critical temperature of the aqueous medium. When the hydrothermal treatment temperature is lower than 100 ° C., the reaction between the A hydroxide and the B hydroxide does not proceed sufficiently, and it is difficult to obtain the target perovskite compound in a high yield. On the other hand, the higher the reaction temperature, the more preferable it is from the viewpoint of accelerating the reaction rate. On the other hand, however, the higher the reaction temperature, the higher the equipment cost and the heat energy cost.
C. or less is preferable, and a range of 100 to 300.degree. C. is usually suitable. After this hydrothermal treatment, the slurry-like reaction mixture is filtered and the solid content is dried, whereby fine perovskite compound particles having an average particle size of 1 μm or less can be obtained.

In the above hydrothermal treatment, the degree of alkalinity of the aqueous medium, that is, the excess degree and concentration of the alkali is adjusted as necessary. Generally, the higher the alkali excess, the smaller the particle size of the perovskite compound particles obtained. Further, the higher the concentration of A hydroxide and B hydroxide in the aqueous medium, the smaller the particle size of the obtained perovskite compound. Therefore, the excess degree of alkali and the concentration of each hydroxide in the hydrothermal treatment may be selected according to the required particle size.

As described above, the perovskite compound particles obtained by hydrothermal synthesis have a particle size of 1 μm, unlike the perovskite compound particles obtained by the conventional calcination method.
Hereinafter, the fine particles are usually in the range of 0.01 to 1 μm, have a uniform particle size distribution, and have a large surface energy.

As described above, the particles of the fine perovskite compound can be produced by the metal alkoxide method or coprecipitation method, which is generally known as a solution method, in addition to the above hydrothermal synthesis. Can also be obtained (for example, functional materials December 1982 issue, pages 1 to 8).

In the metal alkoxide method, water is added to a mixture of an alkoxide of at least one element selected from the group A and an alkoxide of at least one element selected from the group B to hydrolyze the alkoxide. , To obtain a perovskite compound. Further, the alkoxide of the B group element may be hydrolyzed with the hydroxide of the A group element.

As the coprecipitation method, generally, a hydroxide coprecipitation method and an organic acid salt method are known. The hydroxide coprecipitation method is
An alkali is allowed to react with a mixed solution of the salt of the group B element and the salt or hydroxide of the group A element to obtain a mixture of the hydroxide of the group A element and the hydroxide of the group B element. If necessary, this is baked at a temperature of about 500 to 900 ° C. to obtain a perovskite compound. For example, a perovskite compound can be obtained by adding a titanium tetrachloride solution to a barium hydroxide aqueous solution containing excess sodium hydroxide. The organic acid salt method is a complex salt of a water-insoluble organic acid containing a group A element and a group B element by reacting a mixture of a salt of a group A element and a salt of a group B element with an organic acid. Is obtained and pyrolyzed at a temperature of about 500 to 900 ° C. to obtain a perovskite compound. For example, a method using oxalic acid or citric acid as an organic acid is known.

As described above, the average particle size of the perovskite compound is 1 μm or less, preferably 0.5 μ, by any of the hydrothermal synthesis method, the metal alkoxide method and the coprecipitation method.
Particles of m or less can be obtained, and all such perovskite compound particles can be used in the present invention.

However, also in the case of the wet method, depending on the conditions, a precursor for forming a perovskite compound may be produced by the subsequent firing, and such a precursor is also fired together with the perovskite compound by the calcination method. As a result, a perovskite compound is produced, and therefore, it can be used as a perovskite compound by the wet method in the present invention.

As described above, according to the method of hydrothermally synthesizing a mixture of barium hydroxide and hydrous titanium oxide to obtain barium titanate (Industrial Chemistry, Vol. 71, No. 1, 114-118). Page (1968)), it is generally difficult to complete the reaction, and after the hydrothermal reaction, unreacted Ba salt is eluted during the steps of washing and filtering the reaction mixture. Required Ba / T even after firing
It is not easy to obtain a sintered body having an i ratio.

Generally, when a perovskite compound is obtained by hydrothermal synthesis, when the reaction is not completed, an element of group B, for example Ti, exists as a solid compound in the aqueous medium after the reaction, and A Since the elements of the group, such as Ba, exist as water-soluble compounds, the Ba compounds are eluted during the steps of filtering the reaction product and washing with water, which results in the required Ba
A perovskite compound having a / Ti ratio cannot be obtained. Therefore, as already proposed by the present inventors (Japanese Patent Publication No. 4-59261), after the hydrothermal treatment, the group A elements remaining in the aqueous medium are treated with water by a method such as sucking carbon dioxide into the reaction mixture. By immobilizing as an insoluble compound, the elements of group A can be left in the reaction product even when the reaction product is filtered and washed with water. Thus, by drying the reaction product, the required element ratio can be increased. It is possible to obtain the perovskite compound having.

Further, it is generally known that when sintering the perovskite compound particles, the growth of the particles and the electrical characteristics of the sintered body can be controlled by the action of the additive, but also in the present invention. Various conventionally known additives can be used. Examples of such additives include B, Bi, alkali metals such as Li, Na and K, transition metals such as Fe, Mn, Co, Ni and Nb, and compounds of elements such as Si and Al. Can be mentioned.
Such additives may be added at any stage of the preparation of the perovskite compound and its calcination, and thus the compositions of the present invention may contain such additives.

The ceramic dielectric composition according to the present invention contains, as a main component, the perovskite compound obtained by the calcination method and the perovskite compound obtained by the wet method as described above. Here, in the present invention, based on the total weight of the perovskite compound by the calcining method and the perovskite compound by the wet method, the perovskite compound by the wet method is 0.5% by weight or more, preferably 1.0% by weight or more. is there. When the amount of the perovskite compound by the wet method is less than 0.5% by weight, the effect of lowering the firing temperature by mixing is poor. On the other hand, although the upper limit is not particularly limited, it is usually 50% by weight, particularly preferably 20% by weight, in view of economy.

The composition according to the present invention can be obtained by homogeneously mixing the perovskite compound by the calcining method and the perovskite compound by the wet method. Here, this mixing method and means can be based on the powder mixing method and means generally used in the field of electronic materials, but is not particularly limited.

The ceramic dielectric composition according to the present invention is excellent in sinterability at low temperatures, and is therefore 1100 to 100.
By firing at a temperature of 1300 ° C., a ceramic dielectric having a high sintered density, a high relative dielectric constant, a high insulation resistance, a low dielectric loss tangent, and the like and excellent electrical characteristics is provided.

[0029]

As described above, according to the perovskite compound composition of the present invention, it is unexpected that only a very small amount of the perovskite compound by the wet method is contained, and the sintering density at the low temperature is extremely high. And a ceramic dielectric made of the thus obtained sintered body have a high relative dielectric constant, a high insulation resistance and a low dielectric loss tangent, and are excellent in electrical characteristics. .

Therefore, by using the composition according to the present invention, a metal material having a low melting point such as silver can be used as an internal electrode and heat energy can be saved in the production of a laminated ceramic capacitor. Therefore, the manufacturing cost of the laminated ceramic capacitor can be remarkably reduced.

[0031]

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

Example 1 Partial hydrated titanium tetrachloride Partially hydrated titanium chloride (TiCl _2.36 (OH) _1.64 , Ti 16.5 wt% and chlorine 28.
8 wt%) aqueous solution (manufactured by Osaka Titanium Co., Ltd., hereinafter referred to as titanium chloride aqueous solution) 139.3 g (0.4 as Ti)
1250 ml of water was added to 8 mol), and 483 ml of 5.0 wt% ammonia water was added to this aqueous solution over 30 minutes to obtain titanium hydroxide. After washing the titanium hydroxide with water, the titanium hydroxide was filtered off and the barium hydroxide octahydrate (Ba
302.8 g (0.96 mol as Ba) of (OH) ₂ .8H ₂ O) was added and water was added to obtain a slurry having a concentration adjusted to 0.8 mol / l as BaTiO ₃ .

600 ml of this slurry was charged into a 1-liter autoclave made of Hastelloy C, and 700-900
While stirring at rpm, the temperature was raised to 200 ° C in 90 minutes, and 20
Hydrothermal treatment was performed by heating at 0 ° C. for 5 hours. After this, the slurry is filtered and washed with water until chlorine is no longer detected.
It was dried at a temperature of 10 ° C. to obtain BaTiO ₃ . This BaTiO
₃ has an average particle size of 0.1μ as a result of observation with an electron microscope.
It was a spherical substance of m, and X-ray diffraction showed a peak peculiar to cubic BaTiO ₃ . In addition, as a result of analysis with fluorescent X-ray,
The Ba / Ti molar ratio was 0.98.

Next, the average particle size obtained by the calcination method is 1.
3 μm of commercially available high-purity BaTiO ₃ obtained by the wet method B above
1% by weight of aTiO ₃ (Experiment No. 1), 5% by weight
(Experiment No. 2) 10 wt% (Experiment No. 3) and 20 wt% (Experiment No. 4) were added and wet-mixed with pure water in a polyethylene ball mill equipped with zirconium oxide balls. Thereafter, the mixture was taken out of the ball mill and dried, and then 8% by weight of a polyvinyl alcohol aqueous solution as a binder was added to the mixture in an amount of 8% by weight of the perovskite compound mixture, and the mixture was homogenized, and then passed through a 35 mesh sieve. The size was adjusted.

Next, this sized product is pressure-molded at a pressure of 1000 kg / cm ² using a die and a hydraulic press to give a diameter of 2
It was molded into a disk-shaped green pellet having a thickness of 0 mm and a thickness of about 2 mm. After heating the green pellets at a temperature of 400 ° C. for 3 hours to pyrolyze and vaporize the polyvinyl alcohol,
Firing at a predetermined temperature for 3 hours to obtain a sintered ceramic body,
The sintered density was measured. The relationship between the firing temperature and the density of the obtained sintered body is shown in FIG. In addition, BaT by hydrothermal method
FIG. 2 shows the relationship between the amount of iO ₃ added and the density of the sintered body obtained by firing at a temperature of 1200 ° C.

As is clear from FIG. 1, B by the calcination method
The mixture of aTiO ₃ and BaTiO ₃ obtained by the wet method has significantly improved sinterability as compared with the case of using BaTiO ₃ alone obtained by the calcination method. Moreover, as is clear from FIG. 2, Yotsute the addition of BaTiO ₃ by a small amount of wet process BaTiO ₃ by calcination method, it is clear that the density of the sintered body is considerably increased.

Next, both sides of the sintered ceramic body whose sintered density was found to be saturated were polished to a thickness of about 1 mm, and silver was coated on both sides with an ion coater to obtain the obtained ceramic dielectric. The electrical properties of the body were measured. The relative permittivity and the dielectric loss were measured by an LF impedance analyzer manufactured by Yokogawa Hiyuretsu Pats Card Co., Ltd., and the insulation resistance was measured by a PA meter manufactured by Yokogawa Hiyuretsu Pats Card Co., Ltd. Table 1 shows the relative permittivity, dielectric loss tangent and resistivity of the ceramic dielectric. From the results shown in Table 1, it is clear that the composition for dielectric ceramics according to the present invention gives a ceramic dielectric having excellent sinterability and electrical characteristics.

Example 2 139.3 g of titanium chloride aqueous solution kept at a temperature of 40 ° C.
1250 ml of water was added to (0.48 mol of Ti), and 483 ml of 5.0 wt% ammonia water was added to this solution over 30 minutes to obtain a titanium hydroxide slurry. After washing this titanium hydroxide slurry with water, it is filtered and titanium hydroxide is added to barium hydroxide octahydrate (Ba (OH) ₂ · 8H ₂ O) 15 in a nitrogen atmosphere.
Add 1.4 g (0.48 mol as Ba), add water and add B
A slurry having a concentration adjusted to 0.8 mol / liter as aTiO ₃ was obtained.

600 ml of this slurry was charged into a 1-liter autoclave made of Hastelloy C, and 700-900
While stirring at rpm, the temperature was raised to 200 ° C., and the mixture was heated at a temperature of 200 ° C. for 5 hours for hydrothermal treatment. After this, the pH is 6.
Carbon dioxide gas was blown in until it reached 5, immobilized unreacted barium ions were fixed, and then filtered and dried to obtain a BaTiO ₃ composition. The particle size of this BaTiO ₃ composition was 0.09 μm,
The Ba / Ti molar ratio was 1.00.

Next, high-purity barium carbonate (manufactured by Sakai Chemical Industry Co., Ltd.) and high-purity titanium oxide (manufactured by Sakai Chemical Industry Co., Ltd.)
And were wet mixed with pure water at a barium carbonate / titanium oxide molar ratio of 1.00 in a polyethylene ball mill equipped with zirconium oxide balls. Then, the mixture was taken out from the ball mill, filtered, dried, and then at 1150 ° C.
It was calcined for 2 hours. This calcinated product was wet pulverized in the ball mill to obtain BaTiO ₃ having a mean particle size of 1.6 μm by a calcination method.
Got

[0041] After the calcination method BaTiO ₃ composition 10 wt% manganese nitrate aqueous solution by a wet process obtained above in BaTiO ₃ (0.1 wt% as Mn) added by, were wet-mixed in the ball mill 120 in the same manner as in Example 1.
Firing was performed at a temperature of 0 ° C. to obtain a sintered body, and the sinterability and electric characteristics were evaluated. The results are shown in Table 1. It is clear that the dielectric ceramic composition according to the present invention gives a ceramic dielectric having excellent sinterability and electrical properties.

Example 3 Commercially available high-purity BaTiO _{3 having} an average particle diameter of 1.3 μm obtained by the calcination method.
0.0 g was placed in a 1 liter capacity three-necked flask and dispersed in 500 ml of pure water while being heated to 80 ° C. with a mantle heater in a nitrogen stream while stirring. Separately, under a nitrogen atmosphere, 4.93 g of barium isopropoxide (Ba as 0.0
2 mol) and 5.48 g of titanium isopropoxide (0.02 mol of Ti) were dissolved in 20 ml of isopropyl alcohol and heated under reflux for 2 hours. Next, this solution was gradually added dropwise to the dispersion liquid of BaTiO ₃ obtained by the calcination method obtained above to hydrolyze the alcoholate and allowed to cool to room temperature.
Filtered and dried. Then, as in Example 1, firing was performed at a temperature of 1200 ° C. to obtain a sintered body, and the sinterability and electrical characteristics were evaluated. The results are shown in Table 1. It is clear that the dielectric ceramic composition according to the present invention gives a ceramic dielectric having excellent sinterability and electrical properties.

EXAMPLE 4 Barium chloride dihydrate (BaCl ₂ .2H ₂ O) (107.48 g, 0.44 mol) was added to 116.12 g (0.40 mol) of the partial titanium hydroxide chloride aqueous solution used in Example 1. ),
Add water to make 500 ml. Heat to 50 ° C with stirring,
After dissolving barium chloride, 296 g of a 32.4 wt% sodium hydroxide aqueous solution was added to obtain a slurry. This slurry was heated under reflux for 5 hours under a nitrogen atmosphere. After that, the pH was adjusted to 7 with 4N acetic acid, and the slurry was filtered and washed with water until chlorine was not detected.
After drying at 0 ° C., BaTiO ₃ having a particle size of 0.07 μm was obtained.

Next, 10 wt% of the wet-processed BaTiO ₃ obtained above was added to the commercially available calcined BaTiO ₃ used in Example 1, and the mixture was wet-mixed in a ball mill. And sintered at a temperature of 1200 ° C. to obtain a sintered body. Table 1 shows the sinterability and electrical characteristics of the obtained sintered body. It is understood that the composition according to the present invention gives a ceramic derivative having excellent sinterability and electrical properties.

[0045]

[Table 1]

Example 5 Sr (OH) ₂ .8H ₂ O (Wako Pure Chemical Industries, Ltd.) under nitrogen atmosphere
127.6 g (0.48 mol as Sr) and hydrous titanium hydroxide having a concentration of 10.9 wt% calculated as TiO ₂ prepared by the method of Example 1, and water is added to the slurry to prepare a slurry. And further add water to make the slurry concentration 0.8 in terms of SrTiO ₃ .
Adjusted to mol / liter. Next, this slurry was hydrothermally treated in the same manner as in Example 1 to give an average particle size of 0.08 μm.
m spherical SrTiO ₃ was obtained.

High-purity strontium carbonate (made by Sakai Chemical Industry Co., Ltd.) and high-purity titanium oxide (made by Sakai Chemical Industry Co., Ltd.)
And were wet mixed with pure water at a strontium carbonate / titanium oxide molar ratio of 1.00 in a polyethylene ball mill equipped with zirconium oxide balls. Then, the mixture was taken out from the ball mill, filtered, dried, and
It was calcined at 50 ° C. for 2 hours. This calcinated product is wet pulverized in the ball mill and calcined by the calcination method with an average particle size of 1.5 μm.
rTiO ₃ was obtained.

10% by weight of SrTiO ₃ obtained by the hydrothermal synthesis method obtained above was added to SrTiO ₃ obtained by the calcination method, and the mixture was wet-mixed in the ball mill, and then at 1200 ° C. in the same manner as in Example 1. Sintered density 4.62g after firing at temperature
A sintered body of / cm ³ was obtained. Only 1 for SrTiO ₃ by calcination method
The sintered body obtained by firing at a temperature of 200 ° C. has a sintered density
Since it is 3.25 g / cm ³ , it is clear that the composition according to the invention gives a sintered body with a significantly higher sintered density.

Comparative Example 1 Commercially available high-purity BaTiO ₃ obtained by the same calcination method as that used in Example 1 was fired at a temperature of 1200 ° C. or 1350 ° C., which is the same condition as in Example 1, to obtain a sintered body. Obtained. Sinterability and electrical characteristics of this sintered body are shown in FIG. 1 and Table 1. When the firing temperature is 1200 ° C., the density of the sintered body is low, and the relative dielectric constant and other electrical characteristics are poor. Only when the calcination temperature is higher than 1300 ° C. does a sintered body having a sintered density and a relative dielectric constant substantially the same as those of the composition according to the present invention are provided.

Comparative Example 2 BaTiO ₃ obtained by the hydrothermal synthesis method in Example 1 was fired under the same conditions as in Example 1 to obtain a sintered body. Sinterability and electrical characteristics of this sintered body are shown in FIG. 1 and Table 1. According to the composition of the present invention, by using a composition comprising a mixture of a small amount of a perovskite compound by a wet method and a perovskite compound by a calcining method, by firing at a low temperature, a perovskite compound by a wet method is used. It is possible to obtain a ceramic dielectric material having substantially the same sintered density and electrical characteristics as those obtained when only a single material is fired.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the firing temperature of a composition according to the present invention and a composition as a comparative example, and the sintering density of the obtained sintered body.

FIG. 2 shows the hydrothermal method in the composition according to the present invention.
₃ is a graph showing the relationship between the amount of BaTiO ₃ and the sintered density of a sintered body obtained by firing this at a temperature of 1200 ° C.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhisa Hidaka 5-1, Ebishimacho, Sakai City, Osaka Prefecture Sakai Chemical Industry Co., Ltd.

Claims (5)

[Claims] 1. A method comprising: (a) at least one element selected from the group A consisting of Mg, Ca, Sr, Ba, Pb and a rare earth element, and (b) selected from the group B consisting of Ti, Zr, Hf and Sn. A composition containing a perovskite compound containing at least one element as a main component, wherein the perovskite compound is composed of a perovskite compound by a calcination method and a perovskite compound by a wet method in an amount of 0.5 to 50% by weight. A ceramic dielectric composition. 2. The composition for a ceramic dielectric according to claim 1, wherein the wet method is one selected from a hydrothermal synthesis method, an alkoxide method and a coprecipitation method. 3. The composition for a ceramic dielectric according to claim 1, wherein the perovskite compound produced by the wet method has an average particle size of 1 μm or less. 4. The composition for a ceramic dielectric according to claim 1, wherein the perovskite compound obtained by the calcination method has an average particle size of 1 μm or more. 5. A perovskite compound prepared by a calcination method and a perovskite compound prepared by a wet method.
The ceramic dielectric composition according to claim 1, wherein the composition is 1.0 to 20% by weight.