JPS58126610A - 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 The present invention utilizes barium oxide (BaOL titanium oxide (TiO
2) relates to a dielectric ceramic composition composed of samarium oxide (s!n2o3), lead oxide (pbo), and its purpose is to improve the dielectric constant (
The object of the present invention is to provide a dielectric ceramic having a large εr), stable temperature characteristics, and whose temperature coefficient can be varied over a wide range depending on the application.

In recent years, with the advancement of technology for high-frequency circuits that handle microwaves and millimeter waves (hereinafter collectively referred to as microwaves) with wavelengths of several meters or less, efforts are being made to miniaturize these circuits.

Until now, cavity resonators, antennas, etc. 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. T102-based materials are often used as materials suitable for such uses, such as TiO2-Z
r02 & one case, system, CaT 1o3- MgT 1o3- L
a203-2T io2 series, recently Ba (zn3A
Dielectric ceramics such as Ta%)03B&(2n3ANbX)03 series are known. However, when a dielectric resonator is made of these materials, the dielectric constant is 30~30.
For example, the resonant frequency is about 11 G.
If a material with ε1=3Q is used for a dielectric resonator in the X band of Hz, it will be a small unit with a diameter of 5.6 mm and a thickness of about 2.2 mm, but it can be used in the UHF band at a lower frequency of about 2 GHz. In this case, if the material has the same ε and = 3o, the diameter will be about 30.7 mm and the thickness will be about 12.3 cm, which is a significantly larger shape. If the dielectric constant of the material used here can be increased to about 80, the size will be 1 in diameter.
Although it can be downsized to approximately 8.8 mm and thickness of 7 m5 m+m, conventional materials have not been able to satisfy these requirements.

The present invention was made in order to improve the above-mentioned drawbacks, and aims to provide a dielectric ceramic having a large dielectric constant, stable temperature characteristics, and whose temperature coefficient can be varied over a wide range depending on the application. It is something to do.

As a result of various studies on materials that meet the above requirements, the inventors found that
It is represented by the composition formula 203, 6≦I≦23 (molar ratio)
.

67≦y≦82.5 (mole ratio), 2.5≦2≦37.6
(mol%), x+y+z=100 (mol%) range PbO
It has been found that porcelain with a composition in which it is added in an amount that does not exceed 10% by weight of the total amount of both when converted to type 0 is an excellent dielectric porcelain for high frequency use.

The reason for limiting the range of the main component composition will be explained.

BaO amount (,) exceeds 23 molar ratio, or T 10
2 amount (y) is 57 mo/l, less than 4 or 5-03 amount (
When z) is less than 2.6 molar ratio, it becomes difficult to sinter the porcelain, and the no-load Q decreases, making it impossible to measure. If I is less than 5 molar ratios or 2 is more than 37.5 molar ratios, the sintering of the porcelain becomes unstable and the no-load Q decreases, making it impossible to measure. Moreover, when y exceeds 82.6 molar coefficient,
As the sintering of the porcelain becomes unstable, the temperature characteristics change significantly. For this reason,! ,7. Z is preferably within the above range.

However, when adding PbO as a subcomponent, the relative dielectric constant can be increased as its content is increased.
Although it is possible to change the temperature characteristics, adding more than 10% by weight makes sintering unstable and lowers the no-load Q, so the range exceeding 10% by weight is excluded from the present invention. The present invention will be explained below based on examples.

The starting material is chemically highly purified BaCO3tT1.
02.

5rn2!03 and Pbo were weighed to 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 placed in the air at 9oC.
It was calcined for 2 hours at a temperature of 0°C. The calcined product was wet-milled together with pure water in the ball mill described above. After the crushed slurry was dehydrated and dried, 8% by weight of a polyvinyl alcohol solution with a concentration of 3% was added to the powder as a binder to make it homogeneous, and then the powder was sized through a 32-mesh sieve. The sized powder was molded into a disc with a diameter of 20 mm and a thickness of about 8 mm using a mold and a hydraulic press at a molding pressure of 80 kg~. The molded body is placed in a high-purity alumina sheath and heated for 1 to 2 hours in air at a temperature within the range of 1250 to 1550°C, depending on the composition.
The mixture was fired for a certain period of time to obtain dielectric porcelain having the composition shown in the table. Using the obtained ceramic element, the resonant frequency, no-load Q, and dielectric constant were determined by measurements using the dielectric resonator method.

Regarding the temperature dependence of the resonant frequency, from -30℃ to 70℃
The temperature coefficient τf was determined by measuring in the range of °C. The resonant frequency was 2-4 GHz. 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 of the present invention.

* indicates a comparative example.

As is clear from the table, the dielectric ceramic within the scope of the present invention not only has a large relative permittivity value but also a large no-load Q value in the microwave frequency band, and also exhibits stable temperature characteristics. ing. Therefore, the dielectric ceramic of the present invention is useful for stabilizing the temperature dependence of oscillators and resonators, and is particularly suitable for use in the UHF band due to its large dielectric constant, and is suitable for use in small and high-performance electronic circuits. parts can be made. Furthermore, by changing the composition of the material, when a dielectric resonator is assembled using this porcelain, it is possible to provide a temperature compensation effect that eliminates the influence of surrounding metal plates on the temperature characteristics.

As described above, the dielectric ceramic composition of the present invention can provide useful materials not only for microwave dielectric resonators, but also for microwave substrates, dielectric adjustment rods, etc., and can be used industrially. It has great utility value.

Name of agent: Patent attorney Toshio Nakao and one other Procedural amendment July 2z, 1945 To the Commissioner of the Japan Patent Office 1 Indication of the case Patent application No. 9294, 1988 2 Name of the invention Dielectric ceramic composition 3 Amendment Relationship with the case involving a person who commits a patent application Address: 1006 Kadoma, Kadoma City, Osaka Prefecture Name
(582) Matsushita Electric Industrial Co., Ltd. Representative Yama
Toshihiko Shimo 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 5 Subject of amendment 6 Contents of amendment 0) "Permittivity" on page 2, line 11 of the specification has been changed to " Correct the dielectric constant.

(2) The table listed on pages 6-7 of the same document is amended as follows.

* indicates a comparative example.

Claims (1)

[Claims] Dielectric porcelain consisting of barium oxide, titanium oxide, samarium oxide, and lead oxide, whose main components have a composition formula of xBa○-
When expressed as yTiQ2-2Sm2o3, X, 7
．． Z is 5≦X≦23 (Morti), 57≦y≦82.5 (
molti), 2.5≦2≦37.5 (mol%). x + y + z = 100 (molti), and when the lead oxide is expressed as PbO, the pb○ is added and contained in an amount that does not exceed 10% by weight based on the total amount with the main components. A dielectric ceramic composition characterized by: