JPH065117A - Dielectric porcelain composition for high frequency and dielectric material - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composition and a dielectric material having a high dielectric constant and a high Q value in a high frequency region. CONSTITUTION:A dielectric porcelain composition composed of SrO, MgO, and WO3 is expressed by Formula: xSrO.yMgO.zWO3, wherein (x), (y), and (z) satisfy the inequalities: 0.30<=x<=0.70, 0.10<=y<=0.30, and 0.20<=z<=0.40. Particularly, a dielectric material has a perovskite type crystalline phase expressed by Sr(Mg1/2W1/2)O3 as a main crystalline phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel dielectric ceramic composition and a dielectric material having a high dielectric constant and a high Q value in a high frequency region such as microwave and millimeter wave.

[0002]

2. Description of the Related Art Dielectric ceramics are widely used for dielectric resonators, dielectric substrates for MICs, etc. in a high frequency range such as microwaves and millimeter waves.

Conventionally, as a dielectric ceramic of this type,
For example, ZrO ₂ —SnO ₂ —TiO ₂ -based material, BaO—
TiO ₂ materials, (Ba, Sr) (Zr, Ti) O ₃ based materials, Ba (Zn, Ta) O ₃ based materials and the like are known.

The above materials have a frequency of 50 due to various improvements.
Excellent characteristics have been achieved in which the dielectric constant is 20 to 40, the Q value is 1000 to 3000 or more, and the temperature coefficient (τf) of the resonance frequency is around 0 ppm / ° C. at 0 MHz to 5 GHz.

[0005]

Recently, the frequency to be used tends to be higher and the dielectric material is required to have more excellent dielectric properties, especially the Q value. However, in the above-mentioned conventional dielectric material,
At present, it does not have a practically high Q value in the operating frequency region of 10 GHz.

Therefore, an object of the present invention is to provide a novel dielectric ceramic composition and a dielectric material having a high dielectric constant and a high Q value in a high frequency region which can meet such demands. is there.

[0007]

[Means for Solving the Problems] The inventors of the present invention have studied the above-mentioned problems, and as a result, SrO, MgO, WO
_{It is} composed of ₃ and the composition formula based on the molar ratio is xSrO.yMgO
When expressed as zWO ₃ , the above x, y and z are 0.30 ≦ x
≤ 0.70, 0.10 ≤ y ≤ 0.30, 0.20 ≤ z ≤
It is set to a composition range satisfying 0.40, also excellent by a dielectric material, a perovskite-type crystal phase represented by _{Sr (Mg 1/2 W 1/2) O} 3 as a main crystal phase It was discovered that excellent dielectric characteristics can be obtained.

The dielectric ceramic composition of the present invention is composed of a metal composite oxide and is composed of SrO, MgO and WO ₃ , and the composition range of these is shown in the ternary diagram of FIG. In FIG. 1, a region surrounded by points abcdaa, that is, a composition formula based on a molar ratio is xSrO.
When expressed as yMgO · zWO ₃ , the above x, y and z are 0.
30 ≦ x ≦ 0.70, 0.10 ≦ y ≦ 0.30, 0.2
The area is set to satisfy 0 ≦ z ≦ 0.40.

The reason for setting these ratios in the above range is that if the SrO content (x) is less than 0.30, the Q value tends to decrease, and if it exceeds 0.70, sintering tends to be difficult. Is. If the amount of MgO (y) is less than 0.10, the sinterability becomes difficult or the Q value decreases.
If it is more than 0.30, the Q value tends to decrease. Further, if the WO ₃ amount (z) is less than 0.20, the sinterability tends to decrease, and if it exceeds 0.40, the Q value tends to decrease.

The dielectric material of the present invention is made of SrO, M
It is composed of gO and WO ₃ , and these are mainly composed of a perovskite type crystal phase represented by Sr (Mg _1/2 W _1/2 ) O ₃ as a crystal phase. That is, in the perovskite type crystal structure, the A site is formed by Sr,
It has a crystal composed of B site composed of 1: 1 of Mg and W. The material having such a crystal may itself be a polycrystal such as a sintered body or a single crystal.

As a method for producing a porcelain according to the present invention, for example, an oxide of Sr, Mg, W or a metal salt such as a carbonate or a nitrate which forms an oxide by firing is used as a raw material, and these are used in the above range. And weigh well until Then, the mixture is 900-110.
It is calcined at 0 ° C and crushed. Then, this calcined powder is molded into a predetermined shape by a molding method such as press molding or a doctor blade method.

Next, the molded body is fired at 1300 to 1600 ° C. in an oxidizing atmosphere such as air to obtain a relative density of 9
A dielectric ceramic of 0% or more can be obtained.

[0013]

The present invention will be described in the following examples.

SrCO _{3 having} a purity of 99% or more as a raw material,
Using MgCO ₃ and WO ₃ powders, these are shown in Table 1.
Were weighed in the ratio shown in Table 1 and put into a ball mill lined with rubber together with water, and wet mixed for 8 hours. Next, this mixture was dehydrated and dried, and then calcined at 1000 ° C. for 2 hours, and the calcined material was wet-ground for 8 hours by adding water and an organic binder to a ball mill.

Thereafter, the pulverized product was dried and then granulated through a mesh of No. 50 mesh, and the obtained powder was 3000
A disk having a size of 10 mmφ × 5 mmt was formed at a pressure of kg / cm ² . Furthermore, this disk is 1400-15
Firing was performed under the condition of 50 ° C. × 6 hours to obtain a porcelain sample.

With respect to the thus obtained porcelain sample, the relative permittivity (εr) and Q value at a frequency of 10 GHz were measured by the dielectric resonator method, and the temperature change of the resonance frequency in the temperature range from 25 ° C to 85 ° C was measured. The temperature coefficient (τf) of the resonance frequency was calculated from the ratio. The results are shown in Table 1.

[0017]

[Table 1]

According to Table 1, sample Nos. In which the composition of SrO, MgO and WO ₃ deviates from the scope of the present invention. 2, 4,
In Nos. 5 and 12, the Q value was 100 or less, or sintering failure occurred. On the other hand, the sample of the present invention has a relative dielectric constant of 10 or more,
Q value of 1200 or more, temperature coefficient of resonance frequency is 7 in absolute value
0 ppm / ° C or less is achieved, especially SrO: MgO: W
Sample No. in which the ratio of O ₃ is 1: 0.5: 0.5. 7
Shows particularly excellent characteristics, and a Q value of 7900 was achieved with a dielectric constant of 20.

Therefore, the sample No. X-ray diffraction measurement was performed on the porcelain of No. 7, and the results are shown in FIG. According to FIG. 2, it can be understood that the perovskite type crystal structure is obtained from the peak marked with a circle, and its composition formula is Sr (Mg _1/2 W
It is estimated to be _1/2 ) O ₃ . Further, it can be understood from the peaks indicated by ● that the superlattice structure has a regular arrangement of Mg and W.

[0020]

As described in detail above, according to the present invention, S
By blending rO, MgO and WO ₃ in a predetermined ratio, a high dielectric constant and a Q value can be obtained in a high frequency region. As a result, it can be sufficiently applied to resonator materials used in the microwave and millimeter wave regions and dielectric substrate materials for MIC.

[Brief description of drawings]

[1] SrO-MgO-WO _{3 3} indicating the scope of the present invention
It is the original drawing.

FIG. 2 shows a sample No. in the examples. 7 is an X-ray diffraction chart of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hidenori Miyata 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera Corporation

Claims (2)

[Claims] 1. A becomes SrO, MgO, from WO _3, when a composition formula represented as xSrO · yMgO · zWO _3, wherein x,
A high frequency dielectric ceramic composition, wherein y and z satisfy 0.30 ≦ x ≦ 0.70 0.10 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.40. 2. A dielectric material having a perovskite crystal phase represented by Sr (Mg _1/2 W _1/2 ) O ₃ as a main crystal phase.