JPH01275466A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To obtain a dielectric ceramic compd. having high specific dielectric constant, small absolute value of temp. coefft. of the specific dielectric constant, and large unloaded Q value for high frequency by constituting the compsn. primarily of SrO, BaO, TiO2, and Nd2O3. CONSTITUTION:Each 0-15wt.% SrO, SrCO3, BaO, TiO2, BaTiO3, and Bi2O3 are weighed together with, if necessary, 0.1-0.3wt.% sintering aid such as SiO2, MnCO3, etc. in a specified proportion, and dried after mixing in a wet ball mill, etc. The product is pulverized, if necessary, after precalcining at 1,000-1,100 deg.C for several hrs. Then, an org. binder such as PVA, etc., is added to the precalcined product. The mixture is press-formed to a specified shape, then calcined at 1,250-1,400 deg.C for 0.5-several hrs. Thus, a dielectric ceramic compsn. having a compsn. expressed by x, y, and z distributed in a range obtd. by connecting 5 points A-E in the table is obtd. when the compsn. is expressed by the formula[M=Ba1-pSrp(0<p<=1)].

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a dielectric ceramic composition, in particular a dielectric ceramic composition containing strontium oxide (SrO), barium oxide (BaO), titanium oxide (TiO2), neodymium oxide (Nd20a). A dielectric ceramic composition composed of a main component, which has a large relative permittivity (ε) and a small temperature coefficient (TC),
The present invention relates to a dielectric ceramic composition that can provide a dielectric ceramic with a large no-load Q value at high frequencies.

[Prior art] Conventionally, as a dielectric ceramic, M g T 10 s
s゛CaTiO3, SrTiO3, CaTiOs-L
Compositions such as a203 ・2T i 02-MgT i 02 series are used, and by using these compositions, the relative dielectric constant (ε) is 15 to 280, and the temperature coefficient (TC) is +100 to - It is known that dielectric ceramics with a concentration in the range of 3000 ppm/l can be obtained.

[Problem to be solved by the invention] However, in the compositions provided conventionally,
As the relative permittivity increases, the absolute value of the temperature coefficient also increases, and if you try to reduce the absolute value of the temperature coefficient, you will only be able to obtain dielectric porcelain with a small relative permittivity.
A dielectric ceramic composition with good dielectric constant and temperature coefficient has not been obtained.

The present invention solves the above conventional problems and provides a dielectric ceramic composition that has a high dielectric constant, a relatively small absolute value of its temperature coefficient, and a large no-load Q value at high frequencies. The purpose is to provide something.

[Means for Solving the Problems] The dielectric ceramic composition of the present invention contains strontium oxide (S
ro), barium oxide (BaO), titanium oxide (Ti
O2) and neodymium oxide (Nd203) as main components, the composition has the general formula [I] xMO-yTiO2-zNd20s . )) In the MO-TlO2-Nd203 system, x, y
, z are within the range formed by connecting the following five points A-H.

x y
zA 5mol zero 80molk 15m
ol zero B 15 mol! k 80mol! k
5mol! kC30molk 85molk
5mol zero D 30mo1%F 58mo
1%F 12mo1%FE 5 molk
68 mo1%i 27 molk claims (2
) is characterized in that it contains bismuth oxide (Bi2O3) in an amount of 15% by weight or less based on the main component.

That is, as a result of various studies by the present inventors on materials that overcome the above-mentioned conventional drawbacks, in the composition represented by the above general formula [I], x, y, and z connect the above five points A-H. By using bismuth oxide (Bi20a) as the main component and containing 15% by weight or less of bismuth oxide (Bi20a), the dielectric constant (ε) is large and its temperature coefficient (T
It was discovered that a dielectric ceramic having a small C) and a large no-load Q value at high frequencies can be obtained, and the present invention was completed.

The present invention will be explained in detail below.

First, the reason for limiting the range of the main component composition of the dielectric ceramic composition of the present invention will be explained with reference to FIG.

In FIG. 1, first, in the a region outside the above range, the dielectric constant becomes so small that it is not practical. In regions b, c, and d, the relative dielectric constant changes with temperature too much. Furthermore, in the e region, sintering becomes difficult and dense porcelain cannot be obtained. For this reason, it is appropriate that x, y, and z be in the range surrounded by the five points A to E described above.

As for p, if it is O, a high dielectric constant, which is the object of the present invention, cannot be obtained. Therefore, 0<p≦1.

Regarding the addition of Bi2O3, as its content increases, the dielectric constant increases and the temperature coefficient can be improved, but if it is added in an amount exceeding 15% by weight of the main component, the no-load Q decreases. Therefore, it is appropriate that the amount of Bi2O3 added be 15% by weight or less.

In the present invention, it is also possible to add 5i02, MnCO3, etc., which are commonly used as sintering aids, as long as the composition and characteristics of the main components are not changed.

In this case, 5i02 and MnCO3 are the main components of 0
．． It is preferable to add about 1 to 0.3% by weight.

To produce such a dielectric ceramic composition of the present invention,
For example, strontium oxide (SrO), strontium carbonate (SrCO3)% barium oxide (BaO), titanium oxide (TiO2)% barium titanate (BaTi
Powders such as O3), neodymium oxide (Nd203), and if necessary bismuth oxide (Bi2O3) are weighed out to a predetermined ratio and thoroughly mixed using a wet ball mill or the like. Next, after drying this mixture, if necessary, 1
Calcinate for several hours at a temperature of 000 to 1100°C. Although it is not always necessary to perform this calcination, by performing this, the particles tend to be made more uniform and the electric contact characteristics tend to be improved. In the case of calcining, the calcined product is further pulverized using a wet ball mill, etc., and after drying, an appropriate organic binder such as polyvinyl alcohol is added to form granules, which are then press-molded into a predetermined shape. Perform firing. This firing is 1
It is carried out at a temperature range of 250 to 1400°C for about 0.5 to several hours. (Of course, these manufacturing conditions are the most suitable values, and the porcelain composition of the present invention may be manufactured under conditions or methods other than those described above.) [Examples] The present invention will be described below with examples. The present invention will be described in more detail below, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Chemically pure BaTiO3,5r as a starting material
C03, TiO2, Nd2o3, Bi2O3 and 5i0
2. Using MnCO3, these raw materials were weighed so as to have the compounding ratio shown in Table 1, and wet milled with pure water using a ball mill for about 18 hours. After drying the mixed and pulverized raw materials, they were pre-calcined in the air at about 1075° C. for 4 hours, and wet-pulverized again with pure water in a ball mill for about 18 hours. After drying the obtained pulverized material, a binder (a 13% by weight aqueous solution of polyvinyl alcohol) was added to granulate it into particles with a diameter of approximately 16 m.
It was press-molded into a disk shape with a thickness of about 0.7 mm. This disk-shaped sample was fired for 1 hour at the firing temperature shown in Table 1, and dielectric porcelain Nos. 1 to 1 with the compounding compositions shown in Table 1 and FIG.
I got 34.

Silver paste was coated on both sides of the dielectric ceramic thus obtained, and after drying, it was baked at about 810° C. for 3 minutes to form a parallel plate capacitor, and its electrical properties were evaluated.

The results are shown in Table 1.

Note that the power visit rate ε and the no-load Q were measured at 25° C. and 1 MHz. In addition, the temperature coefficient (TC) of the telephone call rate is -55℃
It was determined from measurements at 100 KHz in a temperature range of ~+125°C. Insulation resistance (IR) is DC at room temperature.
looV.

The measurement value for 60 seconds is shown.

As is clear from Table 1, the dielectric ceramic composition within the scope of the present invention has a large specific electrical constant (ε), a relatively small temperature coefficient (TC), and a low no-load Q at high frequencies. It has the excellent property of being large and is suitable for materials for temperature compensation, high frequency, etc.

[Effects of the Invention] As detailed above, the dielectric ceramic composition of the present invention has a high dielectric constant, a relatively small absolute value of its temperature coefficient, and a large no-load Q value at high frequencies. Body porcelain is provided. Therefore, the dielectric ceramic composition of the present invention is
It is extremely useful as a dielectric ceramic for temperature compensation, high frequency, etc.

In particular, in the present invention, bismuth oxide (B i 20a
) in an amount of 15% by weight or less based on the main components, the dielectric constant can be increased and the temperature coefficient can be improved.

[Brief explanation of the drawing]

FIG. 1 is a ternary phase diagram illustrating the composition of the dielectric ceramic composition of the present invention. Agent Patent Attorney Shigeno Warizutsu 1
Illustration procedure amendment l Indication of the case Patent Application No. 103125 of 1988 2 Name of the invention Dielectric ceramic composition 3 Relationship to the case by the person making the amendment Name of patent applicant Name Mitsubishi Mining Cement Co., Ltd. 4 Address of agent Tokyo 1-15-7 Toranomon, Minato-ku 105
TG115 building 8th floor 6 Column for detailed explanation of the invention in the specification subject to amendment. 7. Contents of the amendment (1) On page 5, line 13 of the specification, it is stated that “It is not practical.b.
"c" and "r" are not practical. In region b, C-I
The R product becomes small, which is also not practical. In the C region, the dielectric constant is small and its temperature change becomes large. ” he corrected. that's all

Claims (1)

[Claims] (1) Strontium oxide (SrO), barium oxide (
BaO), titanium oxide (TiO_2) and neodymium oxide (Nd_2O_3) as main components, the composition has the general formula [I] xMO-yTiO_2-zNd_2O_3 ... [I
] {However, M=Ba_1_−_pSr_p(0<p≦1
)}, MO-TiO_2-Nd_2O_3
A dielectric ceramic composition characterized in that in the system, x, y, and z are within the range formed by connecting the following five points A to E. x y z A 5mol% 80mol% 15mol%B 1
5mol% 80mol% 5mol%C 30mo
l% 65mol% 5mol% D 30mol%
58mol% 12mol% E 5mol% 6
8 mol% 27 mol% (2) The dielectric ceramic composition according to claim 1, characterized in that it contains bismuth oxide (Bi_2O_3) in an amount of 15% by weight or less based on the main component.