JPS63261606A - 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 "Industrial Application Field" The present invention is suitable as a dielectric material for microwaves, for example, and has a high dielectric constant, low dielectric loss, and a small temperature coefficient value. , relates to a dielectric ceramic composition whose value can be easily controlled.

"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-4Ti.
0t, (ZrSn)TiO4, Mg'l'i0s-C
Tid! such as aTiO3! Many types of materials have been used.

"Problems to be Solved by the Invention" In general, microwave dielectric materials are required to have properties not shown in (1) to (4) below.

■High relative 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 was made in view of the above-mentioned problems, and an object of the present invention is to provide a dielectric ceramic composition that has a large dielectric constant, a small dielectric loss, and a small temperature coefficient that can be easily controlled. shall be.

"Means for Solving the Problems" In order to solve the above problems, the present invention provides
A dielectric ceramic composition consisting of O, CaO, and TatOa, whose composition is expressed by the general formula: Ba(Co X / 3 Ca y /s Ta !/
3) 0+ + y, /s +Y/3
+s/s, and the composition ratio x, y is in the range of 0.5<X<1.0 0<y<0.5 (however, 0.85<X+y<1.1) be.

In the dielectric ceramic composition of the present invention, the reason why the composition is limited as described above is that if X≦0.5 or y≧0.5, the temperature coefficient (τro) becomes too large and
This is because when x=1.0 or y=o, the relative dielectric constant (εr) becomes small, and when X+y≦0.85, the sinterability deteriorates, and x This is because the dielectric loss (tan δ) becomes large.

That is, the dielectric ceramic composition having the above composition has a high dielectric constant, low dielectric loss, and a small temperature coefficient whose value can be easily controlled.

"Example" Starting materials include barium carbonate (BaCO3), cobalt oxide (Coo), and calcium carbonate (CaCO3).

Using tantalum pentoxide (TatOa), composition ratio x, y
Wet mixing was performed in a ball mill using a scale so that the values were as shown in Table 1 below.

Then, after dehydrating and drying the mixture, the mixture was heated at 1200°C.
The calcined product was further crushed and granulated, then press-molded at a pressure of 1000 kg/ci, and this compact was heated to a temperature of 1600°C for 30 hours. Main firing was performed to obtain a dielectric ceramic sample.

For each dielectric ceramic sample (sample Nol to Na1l shown in Table 1) manufactured by the above process, the relative permittivity (εr), dielectric loss (tanδ), and temperature coefficient at the resonance frequency (τro) of each sample are calculated. 6 values were measured at a frequency of 12 GHz using the dielectric resonator method. Note that the temperature coefficient is +
Measurements were made over a temperature range of 70°C to -50'C. 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. 5, No. 08, and N.
o9 is a sample manufactured based on the composition limited in the present invention, and samples No. 1, No. 6, No. 7, N010, and No.
I is a sample whose composition deviates from the composition defined in the present invention.

Samples No. 2 to No. 5, No. 8, and No. 9 of the examples of the present invention all exhibit relatively high dielectric constants, and have low dielectric loss.
The temperature coefficient is also small, and its value can be controlled.

Sample Not has a range of composition ratios X and y limited in the present invention (
0,5<x<1.0, O<y<0.5), X is a value exceeding the upper limit of the limited range, and A is a value smaller than the lower limit of the limited range. Compared to the sample of the present invention, the relative dielectric constant is slightly lower and the dielectric loss is larger.

Furthermore, Samples No. 6 and No. 7 were examples in which the value of the composition ratio x+y was lower than the lower limit of the range (0.85<x+y<t, 1) defined by the present invention, but the sintering was defective. Also,
Sample NoI O is an example in which X is set to a value smaller than the lower limit of the limited range, and y is set to a value larger than the upper limit of the limited range, but the temperature coefficient is too large compared to the sample of the present invention. There is. And sample Not l has a composition ratio of X+1
This is an example in which the value of / is larger than the upper limit of the range defined by the present invention, but the dielectric loss is larger than that of the sample of the present invention.

In view of the above measurement results, for each value of composition ratios X, y, and X+y, 0.5<X<1.0.0<y<0.5.
It has been found that the range of 0-85<x+y<1.1 is appropriate.

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.

"Effects of the Invention" As explained above, the dielectric ceramic composition of the present invention has Ba
It is composed of O, Coo, CaO, and TatOs, and the ratio of each element is limited to a special value, so it has a large dielectric constant, low dielectric loss, and a small temperature coefficient, and its value is It is excellent because it can be controlled to any value. 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, CoO, CaO, and Ta_2O_5, the composition of which is represented by the general formula: Ba(Co_x_/_3Ca_y_/_3Ta_2_/
_3) O_1_+_x_/_3_+_y_/_3_+_
5_/_3, the composition ratio x, y is in the range of 0.5<x<1.0 0<y<0.5 (however, 0.85<x+y<1.1) Characteristic dielectric ceramic composition.