JPH02164758A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To obtain a ceramics having large dielectric constant and Q under no-load conditions, with the temp. coefficient of the resonance frequency stabilized, and capable of being finely controlled to a desired value by using a composition having specified contents of BaO, ZnO, Ta2O5, NiO, and Nb2O5. CONSTITUTION:The dielectric ceramic composition is shown by formula I (0<x<1 in molar fraction). The composition is limited to the range, because the dielectric constant and Qu are not improved when the amt. (x) in formula II is zero. Consequently, the ceramic is excluded from the ceramic composition. The epsilon1, Qu, and temp. coefficient of resonance frequency are not improved by the ceramic with x=1, and the ceramics is excluded from the ceramic composition. Since the ceramics composition has a large dielectric constant and a low loss, the composition is appropriately used in the SHF zone, and a compact and high-performance electric circuit part can be made from the composition.

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), oxidation tank/L/(Ta2
06).

Nickel oxide 7v (NiO) and niobium oxide (Nb2o)
The present invention relates to a dielectric ceramic composition for a dielectric resonator comprising the component 5).

Conventional technology In recent years, with advances in technology for high-frequency circuits that handle microwaves and millimeter waves (hereinafter collectively referred to as microwaves) with wavelengths of several centimeters or less, these circuits have been made smaller and the overall price has been reduced. This is being actively pursued. Until now, cavity resonators, antennas, etc. have been used in these high-frequency circuits, but the size of these devices is comparable to the wavelength of microwaves, which poses an obstacle to miniaturization. In order to solve this problem, a method has been taken to shorten the wavelength itself by using dielectric five-body porcelain having a high dielectric constant. Conventionally, dielectric materials suitable for such uses include, for example, MgTiO3-CaTiO3 system, MgT103-CaTiOa-La
203-2T 102 series, J3aO-TiO2 series, and porcelains in which some of them are replaced with other elements are often used.

Problems to be Solved by the Invention These materials mentioned above have drawbacks such as low relative permittivity, large dielectric loss, large variation in relative permittivity, and poor temperature stability of resonance frequency. There is. If an attempt is made to change the temperature coefficient of the resonant frequency, there are many practical problems such as a significant drop in the Q under no load.

The present invention has been made to solve these problems, and has a large relative dielectric constant and Q at no load, and a stable temperature coefficient of the resonant frequency, which can be adjusted finely according to the application. The object is to provide a dielectric ceramic composition that can be varied.

Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention is based on the general formula (1-x)Ba(Zn,TaH)03-xB a
(Nt, Nb,)03 (its component composition is in the range of 0<x1) in terms of mole fraction.

Function: In the composition range according to the characteristics of the present invention, the relative dielectric constant and Q at no load are large, and the temperature coefficient of the resonance frequency is stable, and furthermore, by changing the composition, the desired value can be finely adjusted. can be controlled.

Example Examples are shown below.

The starting material is chemically highly purified B a Co3. Z
no2゜T a 20 a s N iOJ OyoD
Nb2o5 was weighed to a predetermined tvm and wet-mixed with pure water in a polyethylene ball mill equipped with an agate ball.

After ball milling, the mixture was heated in the air at a temperature of 1100°C for 2 hours, and a polyvinyl alcohol (V)V with a concentration of 6% was used as a binder.
After adding 8% by weight of the solution and mixing to make it homogeneous, the mixture was sized through a 32 mesh sieve.

The sized powder is molded using a mold and a hydraulic press under a pressure of a
o It was molded into a disk with a diameter of 13 mm and a thickness of about 5 mm using Kq/crl. The molded body was placed in a high-purity alumina sheath and fired in air at a temperature within the range of 1300 to 1650°C for 2 hours depending on the composition to obtain a dielectric ceramic composition. A disk ceramic element with a diameter of 5III m and a thickness of 21 mm was cut out from this ceramic composition, and the resonance frequency, Q (Qu) under no load, and relative dielectric constant (εr) were determined by measurement using the dielectric resonator method. The temperature coefficient of the resonance frequency was measured in the range of -30°C to 70°C, and the temperature coefficient τf was determined. The tangent frequency is 10
It was in the range of ~12G-. 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.

Table * Comparative examples outside the scope of the present invention As is clear from the results shown in the table, the dielectric ceramic composition within the scope of the present invention maintains a relatively large dielectric constant in the microwave frequency band. The Q when unloaded has a large value, and the temperature coefficient of the resonance frequency exhibits stable characteristics. Therefore, the dielectric ceramic composition of the present invention is useful for stabilizing the temperature dependence of oscillators and resonators and finely controlling the temperature coefficient of the resonant frequency, and is a compact and high-performance material suitable for use in the SHF band. Can make electronic circuit parts.

The reason why the composition range of the present invention is limited is as follows: When the amount (x) of Ba(NibNb3A)o3 is zero, the improvement effect for improving the dielectric constant and Qu is not recognized, and therefore it is excluded from the scope of the present invention. Also, x =
Ceramics No. 1 cannot achieve the effect of improving the temperature coefficient of ε1, Qu, and resonance frequency, and are therefore excluded from the scope of the present invention.

Effects of the Invention The dielectric ceramic composition of the present invention has a large no-load Q in the microwave frequency band, a large relative dielectric constant, and also allows the temperature coefficient of the resonant frequency to be finely changed depending on the composition and is stable. Since it can have a certain 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 it is possible to select τf necessary for the circuit, when the dielectric resonator is assembled, it is possible to provide a temperature compensation effect that eliminates the influence of surrounding metal plates on the temperature characteristics. 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. It is.

Claims (1)

[Claims] General formula (1-x) Ba (Zn_1_/_3Ta_2_/_3)
O_3-xBa(Ni_1_/_3Nb_2_/_3)
A dielectric ceramic composition characterized in that it is represented by O_3 (its component composition is in the range of 0<x<1 in terms of mole fraction).