JPS603A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric ceramic composition, and relates to a dielectric ceramic composition suitable for use in 9% high frequency applications or temperature compensation applications.

[Prior art]

For example, dielectric ceramic compositions used in 7II capacitors for temperature compensation, etc. have a relatively small temperature coefficient, a high dielectric constant and a high Q, and have a low temperature dependence, that is, a low rate of change in capacitance. It is hoped that it will not last. And, as a conventional dielectric ceramic composition of this kind,
5rTi03, CaTi01.

MgTiO3, La203*2 TiO2, CaZ
Those whose main component is rO2 etc. are known. According to these compositions.

The dielectric constant is 10-300. Temperature coefficient is +100 to -300
It is also known that the range of 0.times.10-'/''C has been obtained.

However, in these conventional dielectric ceramic compositions, the relationship between the dielectric constant and the temperature coefficient at room temperature is such that the thicker the dielectric constant, the larger the temperature coefficient, and vice versa. The relationship is that the dielectric constant also decreases. For this reason, conventional dielectric ceramic compositions have a small temperature coefficient,
It was not possible to obtain a material with a large dielectric constant.

In addition, in general temperature-compensating ceramic capacitors and dielectric resonators for high-frequency circuits, the dielectric ceramic composition has a small temperature coefficient, a high dielectric constant and a high Q, and the dielectric constant has no temperature dependence. desired. Conventionally, such dielectric ceramic compositions have been TiO2-based 2, for example '1'i.
02- ZrO2-5n02-based tCaTi03-MgT
i03-La203@2 A ceramic composition such as TiO2 type was used. However, when dielectric resonators and capacitors are made with these compositions, the temperature coefficient is
(P PM/"c) has the disadvantage that the dielectric constant is very small at 408 degrees in the area with good temperature characteristics, but the temperature coefficient is small and the temperature dependence of the dielectric constant is linear,
It was difficult to obtain a material with a high dielectric constant.

Further, as BaO.xTiO2 compositions, compositions in which X is 2 to 9 are known for use in temperature compensation, but the above-mentioned problems have not yet been solved.

[Problem that the invention seeks to solve]

The present invention has the advantage that it was not possible to obtain a dielectric ceramic having a large dielectric constant and Q, a small temperature coefficient, good linearity of the temperature characteristic of the permittivity, and a small rate of change in capacitance. It is a solution to a problem.

[Means for solving problems]

In order to solve the above-mentioned problems, two aspects of the present invention are provided.B
a0* 56 mol%~7.69 mo/'
%tLa20318.75%%~51.1
It is characterized by having a composition range of 5 mol%.

By setting the composition within such a range, the object of the present invention can be achieved. It has been found that a dielectric ceramic composition can be obtained that has a large dielectric constant and Q, a small temperature coefficient, and a good linearity of the temperature characteristic of the dielectric constant.

〔Example〕

The present invention will be explained in detail based on examples.

First, TiO2 and BaC0, are converted into oxides and T
iO2 is 67.2%h%~75.0%le%, B
aO is 1.56 mo/L-% to 7.69 mole%*Lax
Os is blended so that the composition ratio is within the range of 18.755 mol 3.15 mol - ○, and this is
After pre-calcining at 00'C for 2 hours, it is coarsely ground to a particle size of 100μm or less, then wet-pulverized using a ball mill, filtered and dried, and then a binder is added. This is 16.57Ellφxo, 6
It was molded into a disk shape of mt and baked at a temperature of 1280°C to 1400°C for 2 hours. Note that when molding into the disk shape, a pressure of 6 tons/d was applied. Silver electrodes were baked on both sides of the dielectric porcelain thus obtained at 800°C to form a capacitor, and the dielectric constant, Q value, and temperature coefficients T, C (P
PM/'C) was measured. Here, the dielectric constant and Q are 1KHz
Measurements were made using a capacitance bridge at a frequency of . Further, the temperature coefficients T and C were calculated using the following equations based on the value of the dielectric constant ε2o at a temperature of 20°C.

T, C= (εT−ε2o) / ε2g(T 20
) (ppm/'C) where ε, T'' is the dielectric constant at C, ε2° is the dielectric constant at 20°C, and T is the measurement temperature (room temperature).

In this way, each sample as shown in Table 1 was prepared,
Their electrical properties such as dielectric constant, Q, and temperature coefficient were measured. Each sample in Table 1 is shown in the binary component diagram in FIG.

Table 1 FIG. 1 is a graph of Table 1.

As is clear from Table 1, La2o3@2Ti0
If z is 95 mol or more, sample Na, 1, 2,
As shown in 3.

It is necessary to raise the main firing temperature to 1680℃, which deteriorates the sinterability and reduces the dielectric constant to 41.
It is insufficient as it is below.

And when Ba0exTiO2 is 25 molar or more.

As shown in samples Nn 18 and 19, the temperature coefficient suddenly increases to the negative side, and the dielectric constant does not increase accordingly, making it impractical.

On the other hand, BaOa x TiO2 is 5.0 mo+%~
25 mol%, La2O2e2 TiO2 is in the composition range of 75 mol% to 95 mol%, the firing temperature is also 162 mol%.
It is not very high at 0°C to 1640°C, and its dielectric constant is 60.
In addition, the value of Q is also 6000 or more, which is sufficiently large.

In addition, below x-2, as shown in sample Na 5, 14,
It is not practical because the Q decrease is extremely high. Sample NC above x-7
As shown in L 6 and 17, ε8 becomes small.

Moreover, as shown in Figure 2, the rate of change in capacity is.

Temperature characteristics with good linearity can be obtained over a wide temperature range. In addition, Figure 2 shows temperature f℃l - capacity change rate (%)
Line 4 indicates the characteristics of the composition shown as sample Nα4 in Table 1, and line 15 also indicates Nα15.
Characteristics for the composition shown as:

As is clear from FIG. 2, it can be seen that the dielectric ceramic composition according to the present invention exhibits extremely high linearity in the temperature change characteristic of capacitance over a wide temperature range from -30°C to +100°C. Similar results were obtained with 9 other samples of the present invention, although 2 were not shown.

〔effect〕

As described above, the present invention has high dielectric constant and Q, low temperature coefficient, very good linearity of temperature characteristic of dielectric constant, very small capacitance change rate, and good sinterability. A dielectric ceramic composition can be provided.

Therefore, according to the present invention, it is possible to provide a dielectric ceramic composition that is very suitable as a material for temperature compensation or high frequency ceramic capacitors, dielectric resonators, and the like.

[Brief explanation of drawings]

FIG. 1 is a Q, T, C, εS characteristic diagram of a binary system showing the composition ratio of the dielectric ceramic composition according to the present invention, and FIG. 2 is a temperature-capacitance change rate characteristic diagram. Patent applicant: TDC Co., Ltd., agent patent attorney
Akira Yamatani

Claims (1)

[Claims] 1) BaO・x Ti02-La2O5・2 TiO
A two-system dielectric ceramic composition (x = 3 to 6) containing Ti0z67.2 mol% to 75.2 mol% in terms of oxide.
A dielectric ceramic composition characterized in that it has a composition ranging from 18.75 mol% to 31.15 mol% BaO, 96 to 7.69 mol% BaO, and 18.75 mol% to 31.15 mol% La203.