JPH07130217A - Manufacture of pb system dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a Pb system dielectric ceramic composition whereby a Pb system dielectric ceramic excellent in a temperature characteristic can be easily and efficiently obtained and this dielectric constant temperature characteristic can be easily adjusted. CONSTITUTION:A raw material of PbO or the like for constituting a Pb system dielectric ceramic composition is compounded to obtain a raw material composition, and by temporarily burning the obtained raw material composition crushed, raw material powder is obtained. A transition metal compound of MnCO3, MnO, etc., is added in a range to 0.34mol% by conversion into a transition metal to the obtained raw material powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a Pb-based dielectric ceramic composition, and more particularly to a method for producing a dielectric ceramic composition containing a transition metal such as Mn or Cr as a depressor.

[0002]

2. Description of the Related Art In a ceramic capacitor such as a multilayer capacitor, a ceramic material having a high non-dielectric constant and a good temperature characteristic is used to realize a large capacity and an excellent temperature characteristic of the dielectric constant. Is required. As such a material, attention is focused on a material obtained by adding a transition metal element as a depressor to a Pb-based dielectric ceramic composition.

For example, Pb (Mg _1/3 Nb _2/3 ) O ₃ −
It is known that a porcelain composition obtained by adding a transition metal element such as Mn or Cr to a PbTiO ₃ system composition exhibits excellent temperature characteristics. The transition metal is added in the form of a compound such as MnCO ₃ , MnO or MnO ₂ when Mn is taken as an example.

Specifically, in manufacturing the above Pb-based dielectric ceramic composition, first, PbO, Nb ₂ O ₃ and Mg are prepared.
Raw materials such as O and TiO ₂ for forming the above Pb-based dielectric ceramic composition and raw materials for supplying transition metals such as MnCO ₃ are weighed and mixed to obtain a raw material composition. Then, the obtained raw material composition is calcined and pulverized to obtain a powder raw material. The obtained powder raw material is mixed with an organic binder such as polyvinyl butyral and the like, and the obtained compact is fired to obtain a ceramic sintered body.

[0005]

As described above, in the production of a conventional Pb-based dielectric ceramic composition containing a transition metal, the transition along with the raw materials for constituting the dielectric ceramic composition such as PbO and MgO. The metal compound was mixed. Therefore, once, in the sintered body obtained by firing the powder raw material obtained as described above, if the temperature characteristics deviate from the desired characteristics, the raw materials are weighed again from the beginning and blended, The complicated process of calcination had to be carried out. Therefore, the process of obtaining a Pb-based dielectric ceramic having desired temperature characteristics was very complicated.

An object of the present invention is to provide a method for producing a Pb-based dielectric ceramic composition which enables easy and efficient production of a Pb-based dielectric ceramic composition having excellent temperature characteristics.

[0007]

The present invention is a method for producing a Pb-based dielectric ceramic composition, which comprises blending a transition metal with a Pb-based dielectric ceramic composition, which constitutes the Pb-based dielectric ceramic composition. To obtain a raw material composition, a step of obtaining a raw material powder by calcining the raw material composition and then pulverizing the raw material composition, and converting the transition metal compound into a transition metal in the raw material powder to 0. A method of manufacturing a Pb-based dielectric ceramic composition, comprising the step of adding up to 34 mol%.

In the present invention, first, only the raw materials for forming the Pb-based dielectric ceramic composition are blended to obtain the raw material composition. This step is carried out by weighing and mixing a predetermined amount of a compound of atoms that constitutes the above-mentioned dielectric ceramic composition such as PbO.

After that, the above raw material powder is obtained by calcining and pulverizing the above raw material composition. The calcination and pulverization steps are conventionally performed to obtain a Pb-based dielectric ceramic composition. It can be carried out according to known methods.

A feature of the present invention is that a dielectric ceramic composition is prepared by adding a compound of a transition metal added as a depressor after the raw material powder is obtained, in a proportion of up to 0.34 mol% in terms of the transition metal. Is to get. That is, the transition metal is added after the raw material powder for the dielectric ceramic composition is obtained, for example, when the organic binder is mixed.

The transition metal that can be used is M
n, Cr, Fe, Ni, Co and the like are mentioned, and these transition metals are added in the form of compounds such as oxides or carbonate compounds such as MnCO ₃ , MnO and Cr ₂ O ₃ .

It is to be noted that the transition metal compound added in the range of up to 0.34 mol% in terms of the transition metal should be 0.
This is because when the content exceeds 34 mol%, the relative dielectric constant is only lowered and the temperature characteristics do not change much further.

The present invention is generally used in a method for producing a Pb-based dielectric ceramic composition. Examples of the Pb-based dielectric ceramic composition for forming such a Pb-based dielectric ceramic composition include, for example, Pb (Mg _1/3 Nb _2/3 ) O ₃ , P
Examples thereof include Pb-based composite perovskite-type dielectric ceramic composition such as b (Ni _1/3 Nb _2/3 ) O ₃ .

[0014]

According to the present invention, the transition metal for changing the temperature characteristics is mixed with the raw materials constituting the Pb-based dielectric ceramic composition, calcined and pulverized to obtain the raw material powder. It is added after obtaining the raw material powder. Therefore, in the manufacturing method of the present invention, when the temperature characteristics of the sintered body obtained by firing the obtained dielectric ceramic composition deviate from the desired characteristics, the raw material powder prepared first is used as it is. It is possible to easily obtain a sintered body exhibiting desired temperature characteristics only by changing the addition amount of the transition metal compound added together with the organic binder and the like.

That is, since the addition of the transition metal compound is carried out after obtaining the basic dielectric ceramic composition raw material, it becomes possible to easily obtain sintered bodies having different temperature characteristics.
In addition, if one kind of the above-mentioned raw material powder is prepared, a plurality of kinds of compositions are prepared by changing the addition amount of the transition metal compound, and the plurality of kinds of compositions are fired to have various temperature characteristics. A sintered body can be easily obtained. Therefore, depending on the characteristics of these sintered bodies depending on the purpose,
The dielectric ceramic composition to be used can be easily determined.

Further, in the present invention, since the amount of the transition metal added to the raw material powder is within the specific range, it is possible to reliably obtain a ceramic sintered body having excellent temperature characteristics.

[0017]

EXAMPLES Hereinafter, non-limiting examples of the present invention will be described. In this example, 0.935 Pb (Mg _1/3 Nb
_A dielectric ceramic composition was manufactured by adding MnCO ₃ to a Pb-based dielectric ceramic composition having a composition of _2/3 ) O ₃ + 0.065PbTiO ₃ .

That is, first, PbO, Nb ₂ O ₅ , M
gO and TiO ₂ were 71.87 g and 22.8, respectively.
4 g, 3.84 g, and 1.59 g were weighed and mixed by a ball mill to obtain a raw material composition. In this raw material composition, the compounding ratio of each material is determined so as to realize the above composition.

Next, the above raw material composition was calcined, then pulverized and mixed in a ball mill to obtain a raw material powder. MnCO ₃ was added to the obtained raw material powder in Table 1 below.
As shown in (1), the dielectric ceramic composition of Sample Nos. 1 to 8 was prepared by adding and mixing so as to have a concentration in the range of 0 to 7000 ppm.

Although the Mn amount is shown in ppm,
Converting this value into mol% of Mn with respect to the dielectric ceramic composition, it is as shown in Table 1 below. The dielectric ceramic compositions of sample numbers 1 to 8 obtained as described above were molded to obtain a plate-shaped molded body having a diameter of 15 mm and a thickness of 2 mm, and the plate-shaped molded body was heated at a temperature of 950 to 1100 ° C. A plate-shaped ceramic sintered body was obtained by firing for 3 hours.

Electrodes were formed on both main surfaces of the obtained plate-shaped ceramic sintered body to form a capacitor, and the relative permittivity, temperature characteristics and dielectric loss of each capacitor were measured. The results are shown in Table 1 below.

[0022]

[Table 1]

The temperature characteristics in Table 1 show the rate of change (%) from the relative dielectric constant at 20 ° C. to −25 ° C. and + 85 ° C. As is clear from Table 1, in sample No. 8 in which the amount of Mn added exceeds 6000 ppm in terms of MnCO ₃ , only the relative dielectric constant is lowered, and the dielectric constant-temperature characteristic is that of sample 7 having a MnCO ₃ concentration of 6000 ppm or less. It turns out that it is not different from the case. That is, 600
It can be seen that even if MnCO ₃ is added in excess of 0 ppm, it is difficult to adjust the dielectric constant temperature characteristics.

On the other hand, MnCO ₃ was added at 6000 pp
when added in a range of up to m, by varying the amount of MnCO _3, it can be changed permittivity-temperature characteristics, thus the dielectric constant temperature characteristic by adjusting the amount of the MnCO ₃ It turns out that it can be adjusted.

Further, as is apparent from the above-mentioned examples, in the method of the present invention, if one kind of the above-mentioned raw material composition is prepared, the dielectric constant-temperature characteristic can be easily obtained only by changing the addition amount of MnCO _3. It turns out that can be adjusted.

Claims (1)

[Claims] 1. A method for producing a Pb-based dielectric ceramic composition, which comprises mixing a transition metal with a Pb-based dielectric ceramic composition, wherein raw materials for forming the Pb-based dielectric ceramic composition are blended. A step of obtaining a composition, a step of calcining the raw material composition and then pulverizing it to obtain a raw material powder, and a proportion of the raw material powder of up to 0.34 mol% in terms of a transition metal compound converted to a transition metal And a step of adding in
A method for producing a Pb-based dielectric ceramic composition.