JPS6196603A - Dielectric ceramic 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 dielectric ceramic compositions, particularly barium oxide (Ba
O), zinc oxide (ZnO), tantalum oxide (T a 2
0 s ), cobalt oxide (COo), and niobium oxide (Nb2Q6).

Conventional configuration and its problems In recent years, with the advancement of high-frequency circuit technology that handles microwaves and millimeter waves (hereinafter collectively referred to as microwaves) with wavelengths of several centimeters or less, this circuit has been miniaturized and the entire circuit has been Active efforts are being made to reduce the price of Until now, cavity resonators, antennas, etc. have been used in these high-frequency circuits, but the size of these devices has become comparable to the wavelength of microwaves, creating an obstacle to miniaturization. To solve this problem, a method has been used to shorten the wavelength itself by using dielectric ceramics with a high dielectric constant. As a material suitable for such uses,
For example, MgTi0-CaTiO3 system, MqT103
CaTiO3-La2032T102 series, recently B
a (Zn1/lAT a%)03-B a (Z
Composite perovskite dielectric ceramics such as n17NbV )03 series have been developed. This Ba(ZnlATa
%)03-Ba(ZnV3Nb%)o3-based dielectric ceramic material has a relative dielectric constant of 30 to 4o, which can be made relatively large, and is effective from the point of view of miniaturization of high frequency circuits. However, depending on the application, it may be necessary to significantly change the temperature coefficient of the resonant frequency of the dielectric resonator in a negative manner for matching with peripheral circuit elements, and from this point of view, Ba(Zn17'
3Ta213)03-Ba (Zn1/1aNb213
)03 series materials, the temperature coefficient of the resonant frequency changes to the positive side, making it impossible to satisfy such requirements.

One aspect of the invention The present invention has been made to improve the above-mentioned drawbacks, and has a large relative dielectric constant and no-load Q, and also has a stable temperature coefficient of the resonant frequency. The present invention provides a dielectric ceramic that can be finely changed to the negative side.

Structure of the Invention As a result of various studies on materials that meet the above requirements, the present inventors found that (1-x)Ba(Zn'V3Ta2IA)0
It has been found that, in the composition represented by 3-xBa(Col/5Nb2II3)03, a composition in the range of 0<X<1 (mole fraction) can be an excellent dielectric ceramic for high frequencies that meets the purpose of the present invention. Ta.

1 Description of Examples Starting materials include chemically highly purified B a C03t Z
n O+Ta2o6. COo and Nb2o5 were weighed to have a predetermined composition, and wet-mixed with pure water in a polyethylene ball mill equipped with an agate ball.

This mixture was taken out from the ball mill, dried, and then calcined in air at a temperature of 1100° C. for 2 hours. The calcined product was wet-milled together with pure water in the ball mill described above.

After filtering and drying the crushed slurry, 8% by weight of a polyvinyl alcohol solution with a concentration of 6% was added to the powder as a binder to make it homogeneous, and the powder was sized through a 32-mesh sieve. The sized powder is molded using a mold and a hydraulic press at a pressure of aooKy/cni with a diameter of J3mtt and a thickness of approximately 5yt.
It was molded into a disk of m. The molded body is placed in a high-purity alumina sheath pot, and depending on the composition, it is heated to 1300 to 1
The dielectric porcelain was obtained by holding and firing at a temperature within the range of 660° C. for 2 hours. A disk porcelain element with a diameter of 5 mm and a thickness of 2 mm was cut out from this porcelain, and the resonant frequency, no-load Q (Qu), and relative dielectric constant (εr) were determined from measurements using the dielectric resonator method.

The temperature dependence of the resonance frequency was measured in the range of -30°C to 70°C, and the temperature coefficient τf was determined. Resonant frequency is 10-12
It was in the GHz range. The results thus obtained are shown in the table. Note that the samples marked with * in the table are comparative examples outside the scope of the present invention, and the other samples are examples within the scope of the present invention.

As is clear from the table, the dielectric ceramic within the scope of the present invention can have a large relative permittivity in the microwave frequency band, exhibit a large no-load Q value, and have stable negative temperature characteristics. It shows. Therefore, the dielectric ceramic of the present invention is useful for stabilizing the temperature dependence of oscillators and resonators and finely controlling the temperature coefficient, and creating small, high-performance electronic circuit components suitable for use in the SHF band. To explain the reason for limiting the composition range of the present invention, Ba(
CoμNb%)03 When the amount (x) is zero, the relative dielectric constant and Q
Since the effect of improving u and improving the temperature coefficient τf of the resonant frequency to the negative side is no longer recognized, it is excluded from the scope of the present invention. Furthermore, ceramics with x = 1 are excluded from the scope of the present invention because the effect of improving relative dielectric constant and Qu is not observed.

Effects of the Invention The dielectric ceramic composition of the present invention has a large dielectric constant in the microwave frequency band, a high no-load Q, and the temperature coefficient of the resonant frequency can be changed finely to the negative side while maintaining a stable value. It is useful for stabilizing the temperature dependence of oscillators and resonators. In addition, since it has a large relative dielectric constant and low loss, it is suitable for use in the SHF band, and small, high-performance electronic circuit components can be made. Furthermore, since the necessary τf can be selected by changing the composition of the material, it is also possible to provide a temperature compensation effect that eliminates the influence of surrounding metal plates on the temperature characteristics when the dielectric resonator is assembled. In addition, the dielectric ceramic composition of the present invention can provide a material useful not only for dielectric resonators but also for microwave substrates, dielectric adjustment rods, etc., and has great industrial utility value. O is

Claims (1)

[Claims] It consists of barium oxide, zinc oxide, tantalum oxide, cobalt oxide, and niobium oxide, and its composition formula is (1-x)Ba(
Zn1/3Ta2/3)O_3-xBa(Co1/3N
b2/3) A dielectric ceramic composition characterized in that its component composition, expressed as O_3, is in the range of 0<x<1 in terms of molar fraction.