JPS63155505A - 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 [Technical Field] The present invention relates to a dielectric ceramic composition suitable for low-noise converters for satellite broadcast receivers, dielectric resonators for microwave circuits in automobile telephones, and the like.

[Prior Art and its Problems] Porcelain dielectric materials have conventionally been used for microwave resonators, inductance matching, and the like. In recent years, as the number of products that apply microwave circuit technology, such as low-noise converters for satellite broadcast receivers and automobile telephones, has increased, the demand for dielectric materials with high dielectric constant and I loss has become stronger. , requirements are becoming more diverse.

Conventionally, these dielectric ceramic compositions include 8aO-T.
i02, (2rSn)Ti04, MgTiO3-CaT
Many TlO2-based materials such as i03 have been used.

These dielectric ceramic compositions are manufactured through the following steps: weighing of materials → mixing → dehydration → drying → granulation → single-piece firing.

Characteristics required for dielectric materials for microwaves include ■High dielectric constant, ■Low dielectric loss, ■Low temperature coefficient, can be freely controlled, and ■Low variation. Can be mentioned. However, in conventional dielectric ceramic compositions, there are few materials that satisfy all of the above characteristics (i), and there are some problems.

[Object of the Invention] An object of the present invention is to provide a dielectric ceramic composition for microwave use that has a high dielectric constant, a small dielectric loss, and a temperature coefficient that can be easily adjusted.

"Structure of the Invention" The dielectric ceramic composition according to the present invention includes SrO and 8aOCa.
O and Ta2O, the main component composition formula is the one-pronged formula xSr 'YBa (CazTaw)Ox+y+z+sw
When expressed as z□, the mole fraction of X, Y, Z, W is 0
<x<I, 0<y<I, 0.27<z(0,3
7,0,63<w(0,73(However, X+Y・I,z
◆It is characterized by being considered to be the period of W.1).

To explain the reason for limiting the number of principal component compositions as mentioned above, at ×・0, the temperature coefficient vfo of the resonant frequency becomes too large on the positive side, and when Y・0, the temperature coefficient τfo of the resonant frequency becomes too large on the negative side. Also, if 2 is smaller than 0227, the temperature coefficient r of the resonance frequency
Fo becomes large on the positive side, and when Z is larger than 0.37, dielectric loss tan6 becomes large.

Since the dielectric ceramic composition of the present invention has the above-mentioned composition, it has a high dielectric constant, low dielectric loss, and
It is possible to obtain excellent VF properties by easily adjusting the temperature coefficient.

“Embodiments of the Invention” Highly purified strontium carbonate (SrC) was used as a starting material.
(h), R acid barium (8aCO3), calcium carbonate (CaCO:+), tantalum pentoxide (Ta2O
5) Use @ and replace these with x, y, z in the above general formula
A predetermined amount was weighed so that , w had the composition ratio shown in the following table, and wet mixing was performed in a ball mill equipped with an agate pole. After dehydrating and drying this mixture, 1
Preliminary firing was performed at a temperature of 100 to 1300°C. This calcined product was wet-pulverized using the ball mill described above. A polyvinyl alcohol binder was added to the powder thus obtained, and the powder was granulated to a FL degree of 50 to 150 meshes. Then, it was press-molded at a pressure of 1,000 kg/cm, and the molded body was fired in air at a temperature of 1,400 to 1,600° C. for 5 hours to obtain dielectric porcelain.

The characteristic i of the dielectric ceramic obtained through the above steps was measured at a frequency of 11.5 GHz by the dielectric resonator method.

The following table shows the relative permittivity εr, dielectric loss tan 5, and temperature coefficient rfo of resonance frequency of various dielectric ceramics determined in this way. In the table, * indicates a composition that falls under the category of the present invention.

(Hereinafter, blank space) From the table above, it can be seen that by using the composition of the present invention, a good custom-made product with a high relative permittivity εr, a small dielectric loss tan6, and a temperature coefficient τf of the resonance frequency close to 0 can be obtained. It can be seen that dielectric ceramic having the following characteristics can be obtained.

"Effects of the Invention" As explained above, according to the present invention, SrO and BaO
A dielectric porcelain composition for microwave use, which consists of CaO and Ta2O5 and has a predetermined composition ratio, has a high dielectric constant, has a small dielectric loss, and whose temperature coefficient can be easily adjusted. can be obtained.

Claims (1)

[Claims] A dielectric ceramic composition consisting of SrO, BaO, CaO, and Ta_2O_5, whose main component composition formula is the general formula xSr・yBa(Ca_zTa_w)O_x_+_y_
When expressed as +_z_+_5_w_/_2, x, y,
z, w are mole fractions, 0<x<1, 0<y<1, 0.2
7<z<0.37, 0.63<w<0.73 (however,
A dielectric ceramic composition characterized in that the range is x+y=1, z+w=1).