JPS63200407A - 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 "Field of Industrial Application" The present invention is directed to dielectric porcelain, which is suitable as a dielectric material for microwaves, has a high dielectric constant, has a small dielectric loss, and whose temperature coefficient can be easily controlled. The present invention relates to a composition.

"Prior Art" Conventionally, it has been used as a constituent material for low noise frequency converters (LNB) of satellite receivers for microwave reception of satellite broadcasting, voltage controlled oscillators (VCO), microwave filters, etc., or as constituent materials for electric circuits. Porcelain dielectrics have been used for purposes such as impedance matching. In recent years, with the development of the information society, the number of products that apply microwave circuit technology, such as low-noise converters for satellite broadcast receivers and car phones, has increased. Body materials are required, and the requirements are also becoming more diverse.

Conventionally, these dielectric ceramic compositions include BaO-4Ti0.
t, (ZrSn)TiO4, MgTiO3-CaTi0
．． Many Tie-based materials such as + have been used.

"Problems to be Solved by the Invention" Generally, microwave dielectric materials are required to have the following characteristics (1) to (4).

■Have a large dielectric constant.

■Less dielectric loss.

■The temperature coefficient is small and its value can be controlled freely.

■ Variations in each of the above characteristics are small.

However, among conventionally known dielectric materials, there are few that satisfy all of the properties described in items 1 to 2 above, and there is a problem that one of the properties listed in 1 to 2 above is insufficient. It had

The present invention has been made in view of the above-mentioned problems, and provides a dielectric ceramic composition that has a high dielectric constant, low dielectric loss, easy control of temperature coefficient value, and little variation in each characteristic. The purpose is to

[Means for Solving the Problems] In order to solve the above problems, the present invention provides BaO, Mg
A dielectric ceramic composition consisting of O, CaO, and TatOs, whose composition is expressed by the general formula: Ba(Mg X/ s Ca y /3 Ta
Z/3)0+ + xy3 + y/
When expressed as y + 5 2 /II, the composition ratio X, )', Z is 1.0>.1>x+y+z>2.9).

In the dielectric ceramic composition of the present invention, the reason why the composition is limited as described above is that when X=1.0 or y=o, the dielectric constant becomes small, and when X≦0.2 or y ≧0.
When it is 8, the dielectric loss (tan δ) becomes large, and furthermore,
This is because when Z≧2.11 or Z≦1.9, the dielectric loss becomes large.

That is, the dielectric ceramic composition having the above composition has a high dielectric constant, a low dielectric loss factor, and an easy control of the temperature coefficient.

"Example" Highly purified barium carbonate (BaCOI) was used as a starting material.
), calcium carbonate (CaC03), magnesium oxide (MgO), tantalum pentoxide (TatOs),
The compositions were weighed so that the composition ratios x, y, and z described above became the values shown in Table 1 described later, and wet mixing was performed using a ball mill equipped with an agate ball.

After dehydrating and drying the mixture, it was heated in air for 12
Temporary firing was performed at a temperature of 00°C. This calcined product was wet-pulverized using the ball mill device.

A polyvinyl alcohol binder was added to the powder thus obtained, and the powder was granulated to a particle size of 50 to 150 mesh. Then, it was press-molded at a pressure of 1,000 kg/am'', and this molded body was heated at 1,600°C in air.
Main firing was performed at a temperature of 5 hours to obtain dielectric porcelain.

Regarding each dielectric ceramic (sample No. 1 = No. 13 shown in Table 1) manufactured by the above process, the relative dielectric constant (εr), dielectric loss (tan δ), and temperature coefficient (τro) at the resonant frequency of each sample are Using the dielectric resonator method, each value is 1
Measurements were made at a frequency of 2 GHz. The results are shown in Table 1.

Below in Table 1, the composition range limited in the present invention will be discussed based on the measurement results obtained in Table 1.

First, in Table 1, samples No. 2 to No. 9 are samples manufactured based on the composition specified in the present invention, and sample No.
1 and sample No. 1 (1-No. 3 are samples whose compositions differ from those specified in the present invention.

In the present invention, for the composition ratio X, t, O>X>0.2
．． Although limited to the range 0.8>y>0, x=1.0
0, the dielectric constant of sample Nol set to y=0 is 23.3
The dielectric loss of sample No. IO with x=0.2 and y=0.8 is 1.72X10-', which is lower than that of other samples. ~No
9, it is clear that the above ranges are appropriate for the values of X and y.

In addition, although the composition ratio 2 is limited to the range 2.1>z>1.9, sample No.
The dielectric loss of sample No. 1 was 1.95X10-', and sample No.
~ It is considerably larger than No. 9, and furthermore, z
The dielectric loss of sample No. 2 set to = 1.9 is 1.7
Since the value is as large as 3×10−′, it is clear that the above range is appropriate for the value of Z.

In Table 1, samples No. 2 to No. 9 having compositions limited by the present invention all have a high relative dielectric constant, a small dielectric loss, and can be easily controlled on the plus side with a temperature coefficient larger than 60. It is clear that there is little variation in the dielectric constant and dielectric loss, and that the values are stable.

For this reason, the dielectric ceramic composition can be used as a resonator of a low-noise frequency converter for high-frequency equipment such as a satellite receiver for satellite communication or a car phone, or as a voltage-controlled oscillator, or as a duplexer or as a microwave. It is suitable for filters and temperature compensation capacitors, and its application to these devices has the effect of making the devices smaller, higher in performance, and lower in cost.

[Effect of the invention J As explained above, the dielectric ceramic composition of the present invention has Ba
It is composed of O, MgO, CaO, and Taxes, and the proportion of each element is limited to a special value, so it has a high dielectric constant, low dielectric loss, and can have a temperature coefficient of any value on the positive side larger than 0. It is an excellent product that can be controlled. Therefore, the dielectric ceramic composition of the present invention can be used for resonators of low-noise frequency converters for high-frequency equipment such as satellite receivers for satellite communications, for voltage-controlled oscillators, and for duplexers and microwave filters. It is suitable for use in temperature compensation capacitors, and its application to these devices has the effect of making the devices smaller, higher in performance, and lower in cost.

Claims (1)

[Claims] A dielectric ceramic composition consisting of BaO, MgO, CaO, and Ta_2O_6, whose composition is represented by the general formula: Ba(Mg_x_/_3Ca_y_/_3Ta_z_/
_3) O_1_+_x_/_3_+_y_/_3_+_
When expressed as 5_z_/_6, the composition ratio x, y, z is 1.0>x>0.2 0.8>y>0 2.1>z>1.9 (However, 3.1>x+y+z >2.9) A dielectric ceramic composition characterized in that it is in the range of >2.9).