JPH06338221A - Dielectric ceramic composition for high frequency - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition having a high dielectric constant and a high Q value in a high frequency region. CONSTITUTION:A dielectric ceramic composition is composite oxide including Ba, Zn, Mg, Nb and W. The composition satisfies a composition formula in molar ratio of the metal elements expressed by aBaO.bZnO.cMgO-dNb2 O5.eWO3, wherein 0.40<=(a)<=0.70, 0<(b)<=0.30, 0<(c)<=0.35, 0<(d)<=0.30, and 0<(e)<=0.35.

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 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, BaO—ZnO—Nb based material, Sr (Zr, N
b, Ta) based materials, BaZnTa—CaTiO ₃ based materials and the like are known.

The above materials have a dielectric constant of 20-40, 1G.
The Q value converted to Hz is 10,000 to 40,000 and the absolute value of the temperature coefficient (τf) of the resonance frequency is 20 to 100 p.
It has characteristics near pm / ° C.

[0005]

However, in recent years, the frequency of use has become higher due to the diversification of equipment used, and dielectric characteristics, particularly high Q value, in such a high frequency region have been required. However, in the conventional dielectric materials as described above, the Q value is still as low as 10,000 to 40,000, and the high Q value of a practical level has not been obtained at present.

Therefore, an object of the present invention is to provide a novel dielectric ceramic composition having a high Q value in a high frequency region and excellent in controlling the temperature coefficient (τf) of the resonance frequency.

[0007]

The present inventors have [Problems To achieve the ## result of adding considered for the problems, the molar _{aBaO · bZnO · cMgO · dNb 2} O 5 · the composition formula by ratio eWO
The inventors of the present invention found that excellent dielectric properties can be obtained by setting a, b, c, d, and e to predetermined values when expressed as ₃ .

That is, the dielectric ceramic composition of the present invention comprises B
It is a composite oxide containing a, Zn, Mg, Nb, and W, and the composition formula based on the molar ratio of these metal elements is aBaO.
- when expressed as _{bZnO · cMgO · dNb 2 O 5} · eWO 3, wherein a, b, c, d, e is 0.40 ≦ a ≦ 0.7
0, 0 <b ≦ 0.30, 0 <c ≦ 0.35, 0 <d ≦
0.30, 0 <e ≦ 0.35, a + b + c + d + e =
It is a composition satisfying 1.00.

In the dielectric ceramic composition of the present invention, Ba
The molar ratio of O is set to 0.40 ≦ a ≦ 0.70 because
When a is smaller than 0.40, the Q value decreases, and 0.
This is because if it is larger than 70, sintering tends to be difficult. In particular, it is preferable that 0.43 ≦ a ≦ 0.67.

Further, the molar ratio of ZnO is 0 <b ≦ 0.30.
The reason is that, when b is 0, the Q value decreases, and when it is larger than 0.30, the Q value decreases and it becomes difficult to sinter. In particular, 0.02 ≦ b ≦ 0.27
It is preferable that

The reason for setting the molar ratio of MgO to 0 <c ≦ 0.35 is that when c is 0, the Q value decreases.
This is because if it is larger than 0.35, the Q value decreases and it becomes difficult to sinter. In particular, 0.025 ≦ c ≦ 0.32
It is preferable that

The reason for setting the molar ratio of Nb ₂ O ₅ to 0 <d ≦ 0.30 is that the Q value decreases when d is 0, and when the d value is larger than 0.30, the Q value becomes smaller. This is because it becomes low and sintering becomes difficult. It is particularly preferable to set 0.02 ≦ d ≦ 0.27.

The reason for setting the WO ₃ molar ratio to 0 <e ≦ 0.35 is that the Q value decreases when e is 0.
This is because if it is larger than 0.35, the Q value is lowered and it becomes difficult to sinter. It is particularly preferable to set 0.005 ≦ e ≦ 0.32.

The dielectric material of the present invention is made of Ba, Z
It is a complex oxide containing n, Mg, Nb, and W, and is mainly composed of a perovskite type crystal phase, and may contain other than the perovskite type crystal phase. 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 based on the present invention, for example, an oxide of Ba, Zn, Mg, Nb, W or a metal salt such as a carbonate or a nitrate which produces an oxide by firing is used as a raw material. Is weighed so as to fall within the above-mentioned range, wet-milled with a ball mill, and dehydrated and dried. After this, the mixture is heated at 500-1500 ° C. for 0.1-1.
After calcining for 00 hours, the calcined product is placed in a ball mill, mixed and pulverized with a solvent and an organic binder, and granulated or sized. Then, the calcinated powder is press-molded at a predetermined pressure to have a predetermined shape and fired in the atmosphere at 1300 to 1750 ° C. for 0.1 to 200 hours to obtain a dielectric having a relative density of 90% or more. You can get porcelain.

In addition, oxides of Ba, Zn, Nb or metal salts such as carbonates and nitrates that produce oxides by firing, oxides of Ba, Mg, W or carbonates that produce oxides by firing, Metal salts such as nitrates are separately weighed so as to have the above composition, and further wet-milled in a ball mill, dehydrated and dried, and 0.1 to 100 at 500 to 1500 ° C.
Temporal calcination treatments are performed separately, and the respective compounds are simultaneously put into a ball mill and mixed and pulverized with a solvent and an organic binder. The dielectric ceramic composition of the present invention can also be obtained by adopting the same method as the above in the subsequent steps.

[0017]

The present invention will be described in the following examples.

BaCO _{3 having} a purity of 99% or more as a raw material,
Powders of ZnO, MgCO ₃ , Nb ₂ O ₅ and WO ₃ were used and weighed in the proportions shown in Table 1 and put into a ball mill lined with rubber together with water and wet mixed. Then, the mixture is dehydrated and dried, and then 1200
It was calcined for 2 hours at 0 ° C., and the calcined product was wet-ground 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 to obtain 1 ton of the obtained powder.
A disk having a size of 12 mmφ × 8 mm was formed at a pressure of / cm ² . Furthermore, this disk is 1400 to 1650 ℃
It was fired under the condition of × 6 hours to obtain a porcelain sample. This porcelain sample was processed to obtain a disk having a size of 8 mmφ × 5 mm.

With respect to the thus obtained porcelain sample, the relative permittivity (εr) and Q value at a frequency of 7 to 12 GHz were measured by the dielectric resonator method, and 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 temperature change rate. The Q value was converted into the Q value at 1 GHz from the relationship of Q value generally established in the microwave dielectric × measurement frequency f = constant. The results are shown in Table 1.

[0021]

[Table 1]

According to Table 1, the sample No. whose compounding composition deviates from the scope of the present invention. In Nos. 15 to 24, the Q value was 1000 or less, or sintering failure occurred. On the other hand, the sample of the present invention achieved a relative dielectric constant of 15 to 40, a Q value of 45,000 or more, and a temperature coefficient of resonance frequency of 36.8 ppm / ° C. or less in absolute value. Moreover, the temperature coefficient of the resonance frequency is 0 (Sample N
o.2) is obtained, and it is easy to adjust the temperature coefficient of the dielectric porcelain of the present invention near 0, and for example, it has excellent characteristics when used as a dielectric porcelain for a dielectric resonator. I understand.

Incidentally, other materials such as Ta ₂ O ₅ may be added to the porcelain composition of the present invention. Further, in Table 1, defective sintering includes cracks, deformation, unsintered, evaporation, and other defective sintering.

[0024]

As described above in detail, according to the present invention, B
It is a composite oxide containing a, Zn, Mg, Nb, and W, and the composition formula based on the molar ratio of these metal elements is aBaO.
- when expressed as _{bZnO · cMgO · dNb 2 O 5} · eWO 3, a, b, c, d, by the e with a predetermined value,
A high dielectric constant and 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, dielectric substrate materials for MIC, electronic parts, and the like.

Claims (1)

[Claims] 1. A Ba, Zn, Mg, Nb, a composite oxide containing W, composition formula by molar ratio _{aBaO · bZnO · cMgO · dNb 2} O 5 · of these metal elements
When expressed as eWO ₃ , a, b, c, d, and e are 0.40 ≦ a ≦ 0.70 0 <b ≦ 0.30 0 <c ≦ 0.35 0 <d ≦ 0.30 0 < e ≦ 0.35 a + b + c + d + e = 1.00 is satisfied, the dielectric ceramic composition for high frequencies.