JPS58185482A - 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 The present invention provides barium oxide (B2Ld), titanium oxide (Ti
This article relates to a high-frequency dielectric ceramic composition composed of the following components: samarium oxide (SIn205), and aluminum oxide (Mu1203). The unloaded Q (Qu
) is large, the temperature coefficient (τf) of the resonance frequency has a stable value, and the temperature coefficient can be varied over a wide range depending on the application.

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) /l/ or less, miniaturization of these circuits has been actively promoted. It is being

Until now, cavity resonators, antennas, and the like have been used in these high-frequency circuits, but their size is comparable to the wavelength of microwaves, which has been an obstacle to miniaturization. In order to solve this problem, a method has been taken to shorten the wavelength itself by using dielectric ceramics with a high dielectric constant. TiO2-based materials are often used as materials suitable for such applications, such as T10.
2- ZrO2-SnO2 system, CaTiOs -M
gTi0g -LIL205-2TiO2 series, recently Ba (Zn+/, Ta215) 03- Ba(Z
Dielectric ceramics such as n1/3Nb2/3)06 series are known. However, when making a dielectric resonator with these materials, the dielectric constant is as low as about 3o, so for example, an X-band dielectric resonator with a resonance frequency of about 11G11z uses a material with εr-30. In this case, the diameter is 56WIL
, it will be a small unit about 2.2 meters thick, but the frequency will be lowered to 2G! When used in the UHF band around Iz,
When using the same material of εr-30, the diameter is about 30.711 mm and the thickness is about 12.3 mm, which makes the shape considerably larger. If the dielectric constant of the material used here can be increased to about 8o, the size will be 18mm in diameter.
86, it can be made smaller with a thickness of about 7.5 stages,
Conventional materials have not been able to satisfy these requirements.

The present invention has been made to improve these drawbacks, and has improved relative dielectric constant and no-load Q, has a stable temperature coefficient of resonance frequency, and can vary this temperature coefficient over a wide range depending on the application. The object of the present invention is to provide dielectric ceramics that can be used in various ways.

As a result of various studies on materials that meet the above requirements, the inventors found that x BaO-y TiO2-z Smz O
In the composition of 3 and 1, 6≦X≦ at 7%
23. For the main components in the range of 57≦y≦82・5, 2・6≦2≦37・6゜x+y+z=100, Al
It has been found that porcelain having a composition in which 2O3 is added in an amount not exceeding 3% by weight becomes an excellent dielectric porcelain for high frequency use.

To explain the reason for limiting the range of the main component composition, BaO
The amount (X) is more than 23 mo/L/% or TiO2
amount) is less than 57 mo/L/% or the amount of Sm2O3 (Z
) is less than 2.6 mo/I/%, it becomes difficult to sinter the porcelain, and the no-load Q decreases, making it impossible to measure. However, if X is less than 5 mo) or 2 is more than 37.5 mo, the sintering of the porcelain becomes unstable, the no-load Q decreases and becomes unmeasurable, and if y becomes 82
- If it exceeds 6 molts, the sintering of the porcelain becomes unstable and the temperature characteristics change significantly, so it is excluded from the scope of the present invention. □゛Additionally, the addition of the subcomponent Mu 1203 can increase the unloaded Q and change the temperature characteristics as the amount added increases, but if it is added in excess of 3% by weight, , the sintering becomes unstable and the no-load Q decreases, so it is excluded from the scope of the present invention.

The present invention will be explained below based on Examples.

As starting materials, chemically high-purity BaCO5, TiO2°Sm20s, and Mu1205 were weighed to give a predetermined composition, and wet-mixed with pure water in a rubber-lined 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 900° C. for 2 hours. The calcined product was wet-pulverized in the ball mill described above together with pure water. After dehydration and drying using a pulverizable sieve, 8% by weight of polyvinyl 7/L'coal solution with a concentration of 3% 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 was molded into a disk with a diameter of 0 m, a diameter of 20 mm, and a thickness of approximately 8 mm using a mold and a hydraulic press at a molding pressure of 8 o OKV2. The molded body is placed in a high-purity alumina container or a pot, and heated in air at a humidity of 1 to 1,250°C to 1,550°C, depending on the composition.
The mixture was held for 2 hours and fired to obtain dielectric porcelain having the composition shown in the table. Using this ceramic element, the resonant frequency, no-load Q, and relative dielectric constant 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 2~4GII
It was z. The experimental results are shown in the table. In the table, the samples marked with * are comparative examples outside the scope of the present invention, and the other samples are examples within the scope of the present invention.

* indicates a comparative example.

As is clear from the table, in the dielectric ceramic within the scope of the present invention, the no-load Q can be increased while keeping the dielectric constant high. Furthermore, since the dielectric ceramic of the present invention exhibits stable temperature characteristics, it is useful for stabilizing the temperature dependence of oscillators and resonators, and its large dielectric constant makes it suitable for use in the UEF band. It is suitable for making small, high-performance electronic circuit components. Furthermore, since the value of τf can be selected within a wide range by changing the material composition, when the dielectric resonator is assembled, it can have a temperature compensation effect that eliminates the influence of the surrounding metal plates on the humidity characteristics. Furthermore, the dielectric ceramic composition of the present invention has
It can provide a useful material not only for dielectric resonators but also for microwave substrates, dielectric adjustment rods, etc., and has great industrial value.

Claims (1)

[Claims] A dielectric porcelain made of barium oxide, titanium oxide, samarium oxide, and aluminum oxide, whose main component composition formula is x
When expressed as Bao-yTio2-zsm203, x, y, and z are 5≦X≦23 in molar percentage.
57≦y≦82・5.2・6≦2≦37・5, x+y+
z=100, and for this main component Al2O
1. A dielectric ceramic composition characterized in that 5 is added in an amount not exceeding 3% by weight.