JPS5925750B2 - dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides dielectric ceramic compositions, particularly BaO, TiO2,
This article relates to a high-frequency dielectric ceramic composition composed of the components of ceo2 and ceo2, and its objectives are to have a large relative permittivity ε by ρj, a small dielectric loss D, and a low temperature dependence of the relative permittivity. It is an object of the present invention to provide a dielectric ceramic composition which has a linear temperature coefficient and whose temperature coefficient can be varied over a wide range by changing the composition ratio depending on the situation.

Conventionally, dielectric materials have been applied in the microwave region to impedance matching of microwave circuits, dielectric resonators, and the like. In recent years, especially as the technology of integrating microwave circuits has progressed. Active efforts are being made to use dielectric ceramics with high dielectric constant and low loss to stabilize the frequency of oscillators, bandpass filters, etc., and to miniaturize them. Until now, BaO has been used as a suitable dielectric material for these applications.
- TiO2-based porcelain and porcelain in which part of TiO2 has been replaced with other elements, and also TiO2, which has a negative value to adjust the temperature coefficient of dielectric constant, and dielectric porcelain and glass, which have a positive value. Often a combination is used.

However, these materials have many practical problems, such as low dielectric constant, large dielectric loss, and inability to obtain the desired temperature coefficient when used as a dielectric resonator. It was. The inventors investigated various materials that do not have these drawbacks, and found that the general formula xBaO-yTi
In the composition represented by O2-Zceo2, 14≦X≦
It has been found that porcelain having a composition within the ranges of 30 mol%, 56≦y≦75 mol%, 6≦z≦36 mol%, and x+y+z=100 mol% can be an excellent dielectric ceramic material for high frequencies.

Hereinafter, the present invention will be explained based on Examples.

Starting materials include chemically highly purified BaCO3, TiO2,
and CEO2 were weighed to have 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-milled together with pure water in the ball mill described above. After dehydrating and drying the crushed slurry, 8% by weight of a 3% polyvinyl alcohol solution was added to the powder as a binder to make it homogeneous, and the mixture was sized through a 32 mesh sieve. The sized powder was molded using a mold and a hydraulic press at a pressure of 800k9/ to a diameter of 13J7!1.
It was formed into a disk about 1 inch thick. The compact was placed in a high-purity alumina pot. 1150-130 in air depending on composition
Hold and bake at a temperature within the range of 0°C for 1 hour. Dielectric ceramics having the composition shown in the table below were obtained. After baking commercially available silver electrode paste at 800°C on both sides of the resulting porcelain to create electrodes, the capacitance, dielectric capacitance, and dielectric loss D were measured at a frequency of 1 MHz using a 6 automatic capacitance bridge. The relative dielectric constant ε was determined from the dimensions of the ceramic element. Temperature coefficient of relative permittivity γk (Ppm/C) (Ba-4) Determined from changes in capacitance in the temperature range from C to +80°C.The experimental results are shown in the table below.In addition, in the table above, * The samples with marked sample numbers are comparative examples outside the scope of the present invention, and the other samples are examples of the present invention. That is, the amount of BaO (
x) is 30 mol% or more or TiO2 amount (y) is 56
When the amount of CeO2 (z) is less than 6 mol%, the dielectric loss and the temperature coefficient of the dielectric constant become large. Also. If XOS is less than 4 mol %, y is more than 575 mol %, or z is more than 36 mol %, the dielectric loss becomes large and these are excluded from the scope of the present invention. As is clear from the table above. The dielectric ceramic composition of the present invention has a large dielectric constant and small dielectric loss in a high frequency region.

Claims (1)

[Claims] 1 A dielectric ceramic made of barium oxide, titanium oxide, and cerium oxide, whose composition formula is xBaO-yTiO
When expressed as _2-zCeO_2, its component composition is 4
≦x≦30 mol%, 56≦y≦75 mol%, 6≦z≦3
6 mol%, x+y+z=100 mol%.