JPS5937524B2 - dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to dielectric ceramic compositions, particularly PbO, CaO,
This relates to a ceramic composition for microwave dielectric resonators composed of Nb2O5 and Sb2O5 components, which has a large relative dielectric constant (ε), a large no-load Q, and a low temperature coefficient (τf) of the resonance frequency. The present invention aims to provide an excellent ceramic composition for microwave dielectric resonators.

BACKGROUND ART Dielectric materials have been applied to impedance matching of microwave circuits, dielectric resonators, etc. in the microwave region.

In recent years, especially with advances in microwave circuit integration technology, microwave dielectrics with high dielectric constant, low loss, and excellent temperature stability have been developed to create small and inexpensive microwave devices. There is a need for ceramic compositions for resonators. Until now, the dielectric materials suitable for these applications include BaO-TiO2-based porcelain, porcelain in which some of the elements of this system are replaced with other elements, and also porcelains with negative temperature coefficients of dielectric constant. A combination of dielectric ceramic or glass, which has a positive value with TiO2, is often used.

However, these materials have large dielectric loss and
There are drawbacks such as large variations in the temperature coefficient of the dielectric constant, or too large a temperature coefficient of the resonant frequency when used as a dielectric resonator.

Further, if an attempt is made to change the temperature coefficient of the resonant frequency depending on the circuit, there are many practical problems such as a significant decrease in Q. Furthermore, in order to miniaturize the microwave circuit,
It is desired that the dielectric constant of dielectric ceramic be as large as possible. The dielectric ceramic composition of the present invention eliminates these drawbacks, and has aPb0-bCaO-cNb2
In the composition represented by 05-dSb205 system, 70
．． 0≧a≧14.0 (mol%), 67.4≧b≧1.4
(mol%), 27.6≧c≧0.5 (mol%), 28.
1≧d≧1.0 (mol%), a+bfc-ld■10
This is based on the discovery that porcelain with a composition in the range of 0 (mol %) has excellent properties at microwave frequencies.

The present invention will be explained below based on Examples. Chemically high purity PbO) caco3, Nb2 as starting materials
O5 and Sb2O5 were weighed to a predetermined composition and wet mixed with pure water in a rubber-lined ball mill equipped with an agate ball.

After taking out this mixture from the ball mill and drying it,
Molding pressure 400kg/Cd, diameter 5011, thickness approx. 25
A disk of n is molded and heated at a temperature of 850°C in air for 2 hours.
Calcined for an hour. The calcined product was placed in the above ball mill together with pure water and wet-pulverized. After the crushed slurry is dehydrated and dried, 8% by weight of a 3% concentration polyvinyl alcohol solution is added to the powder as a binder to make it homogeneous. Next, 3
The sized powder obtained by passing through two mesh sieves was molded into a disk with a diameter of 21W1Ls and a thickness of 9n using a mold at a pressure of 800 kg/Crli. The molded body was placed in a high-purity alumina sagger and fired in air at a temperature within the range of 1300 to 1150°C for 2 hours depending on the composition to obtain dielectric magnetism having the composition shown in the table below. A microwave dielectric resonator method was used to measure the characteristics at a microwave frequency (3 GHz).

Cut out a disc-shaped porcelain of a size such that the ratio t/D between the thickness t and the diameter D of the porcelain is approximately 0.4, and calculate the resonance frequency of the TEOl δ mode at the micro frequency of this porcelain and the no-load Q
and the temperature coefficient (τf) of the resonance frequency was measured. The temperature coefficient was measured in a temperature range of -30°C to 70°C. The results are shown in the table below. In the table below, samples with sample numbers marked with * are comparative examples outside the scope of the present invention, and the other samples are those of the present invention. As is clear from the soil surface, the dielectric ceramic composition of the present invention has a large relative permittivity (εr) at microwave frequencies, a large no-load Q, and an improved temperature coefficient at the resonant frequency. It has characteristics.

In addition, by changing the composition ratio of the porcelain material, it is possible to obtain an arbitrary value of the temperature coefficient of the resonant frequency between positive and negative while keeping the dielectric constant large. It is easy to compensate for temperature coefficients. The dielectric ceramic of the present invention is a material suitable not only for use in dielectric resonators but also for substrates of microwave circuits or stream wave devices, and has great industrial value.

Claims (1)

[Claims] 1 aPbO-bCaO-cNb_2O_5-dSb_
In the composition represented by 2O_5, 70.0≧a≧1
4.0 (mol%), 57.4≧b≧1.4 (mol%),
2.76≧c≧0.5 (mol%), 28.1≧d≧1.
0 (mol%), a+b+c+d=100 (mol%).