JPS61253709A - 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 relates to a dielectric ceramic composition for a dielectric resonator having a resonance frequency of 10-odd GH2.

[Conventional technology]

No-load Q of a dielectric resonator with a resonant frequency of 10-odd GHz
An excellent one is about 10,000. The dielectric of this conventional dielectric resonator contains Ba.[ZnhTah)2
A dielectric ceramic composition represented by the composition formula: /3.(ZnzNbH)t, -3.03 was used.

[Problem that the invention seeks to solve]

The conventional dielectric ceramic compositions described above were expensive. The reason for this is that the firing temperature in the manufacturing process is as high as approximately 1,600°C, which increases the equipment cost of the firing furnace, its repair cost, and the cost of thermal energy, which increases manufacturing costs. There is a need for dielectric ceramic compositions that can be fired at high temperatures.

This invention was devised based on the above-mentioned demand, and provides a dielectric ceramic composition that is cheaper than conventional compositions.

[Means to solve the problem]

The dielectric ceramic composition of the present invention that achieves the above object is B
a ・(Mg (X)Co (1-X))s・Nb2
X in the composition formula represented by /-1-03 is 0.25 to 0.9
It consists of a composite peropskite in the range of 5.

〔Example〕

Next, Ba・(Mgo,
A method for producing a ceramic composition called sCo6,4)hNb:h.03 will be described.

First, 98.67g of BaCo3 powder, 4g of MgO powder
．． 03g of Nb2O3 powder, 5.00g of Coo powder, and 44.26g of Nb2O3 powder were weighed. This weighed powder was placed in a ball mill with pure water and wet mixed for 24 hours.

The mixture thus obtained was hydrophilized and dried at a temperature of 150°C for 5 hours, and then calcined at a temperature of 1100°C for 2 hours. Next, the calcined product was ground in a ball mill. 3'0g of polyvinyl alcohol was added to the pulverized product, mixed with a crusher, and granulated by passing through a 60-mesh sieve. Put 0.66 g of these granules into a mold,
3ton/C! +1 pressure was applied. By repeating this pressure molding, the diameter 7. Onφ, thickness 3.5
20 (flit) crane disks were produced.Subsequently, these disks were fired at a temperature of 1400℃ for 4 hours, and the diameter was about 6 mm.
A dielectric ceramic disc having a thickness of about 3.1 u was obtained.

Lap and polish both sides of these dielectric porcelain discs.

The thickness t is 3. OOm and designated as sample 3.

Next, we prepared a dielectric resonator using sample 3 as a dielectric at 25°C.
The test method and results for measuring the relative dielectric constant ε and Q without load at a temperature of are explained below.

First, after measuring the diameter of the sample 3 mentioned above with a micrometer,
A measurement system consisting of an A sweep oscillator, an 8410A network analyzer, an 8743A test unit, and a computer was used to measure the relative dielectric constant of 8 and the no-load Q.

The above test unit includes two metal end plates (diameter 241 m, thickness 31 m) for electrodes of a dielectric resonator.
First, the sample 3 is sandwiched between these end plates to form a dielectric resonator. Next, the resonant frequency f of this resonator and the insertion loss dB during resonance are measured. Then, the measured value of the insertion loss dB at this resonance and the above-mentioned diameter of the sample 3 which was actually measured in advance.

By inputting the thickness t into the computer, the dielectric constant ε and the unloaded Q of the dielectric resonator under test are respectively calculated, and the results are printed out.

The relative dielectric constant ε determined in the above measurement system is determined according to a computer program.

πD, resonant wavelength λo ”C/f o *propagation wavelength λ
g=2t, Bessel function of the second kind v2-(πD/λ0) [
(2072g)2-1], the Bessel function of the first kind u2 is measured or calculated, and from these values ε=(λo/πD)
2 (u2+v2)+1. Also, the no-load Q is calculated as follows from the computer program: load QL'=fO/f2 ft' (power half width)
, aH=10-τl.../20 are obtained, and from these values, it is obtained using the arithmetic expression Q=QL/1 at.

The relative permittivity ε of the 20 samples determined as described above
The average value is 32.7. The maximum value is 33. (L minimum value is 32
．． It was 3. Moreover, the average value of Q of 20 samples without load is 11()00. The maximum value is 12500. The minimum value is 108
It was 00. These average values are calculated as the value of X in the above composition formula,
It is shown in the sample number 3 column of the table below along with the firing temperature FT.

Furthermore, the value of X in the composition formula represented by Ba.
(Sample 1), 0.40 (Sample 2), 0.8
The dielectric ceramic compositions of 0 (sample 4) and 0.95 (sample 5) were the same as sample 3 described above, except that the firing temperature FT (1370 to 1450 °C) was slightly different depending on the respective composition. Test dielectric resonators were made using the method described above, and the characteristics of these resonators were determined using the same methods as above.

The average value of each characteristic and the above firing temperature FT are shown in the table below.

As is clear from the above results, Ba・[Mg(×)
In the composition formula represented by CO(1-x)]L/'1'Nb2/+103, a dielectric ceramic composition in which X is in the range of 0.25 to 0.95 has a firing temperature FT of 1370 to 1
The temperature was 450°C. Furthermore, the dielectric constant ε of a dielectric resonator using these dielectric ceramic compositions is 31.8 to 3.
4.1, and the no-load Q is.

It was 10,300 to 11,500.

In addition, in the measurement system mentioned above, one of the dielectric resonators 2
When the temperature coefficient of the resonant frequency in the temperature range of 5 to 100°C was determined, all samples were found to be in the range of O±6 ppm/'C.

A dielectric ceramic composition in which X is less than 0625 in the above composition formula has an unloaded Q of 10000 in a dielectric resonator.
Since this result does not satisfy the premise of this invention, it is excluded from the scope of this invention. Also.

A dielectric ceramic composition in which did.

〔Effect of the invention〕

As explained above, the dielectric ceramic composition of the present invention can obtain properties equivalent to those of conventional compositions and can lower the firing temperature FT during the manufacturing process to 1370 to 1450°C. A dielectric ceramic composition that is cheaper than conventional dielectric ceramic compositions can be obtained in terms of equipment such as a firing furnace and thermal energy for firing. Specifically, a cost reduction of about 10% is expected compared to conventional dielectric ceramic compositions that require a firing temperature FT of 1600° C. or higher for sintering.

Claims (1)

[Claims] Ba・[Mg_(_x_)Co_(_1_-_x_)
] A dielectric ceramic composition in which x in the composition formula represented by_1_/_3・Nb_2_/_3・O_3 is in the range of 0.25 to 0.95.