JP3347613B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition having a low relative dielectric constant and a high Q value in a high frequency region such as a microwave and a millimeter wave, and more particularly, to a dielectric resonator,
High frequency electronic components and MICs such as filters and capacitors
The present invention relates to a dielectric ceramic composition most suitable for a dielectric substrate for use, a waveguide for millimeter waves, and the like.

[0002]

2. Description of the Related Art Conventionally, dielectric porcelain has been widely used in dielectric resonators, MIC dielectric substrates, and the like in high-frequency regions such as microwaves and millimeter waves. Recently, dielectric waveguides have been applied to millimeter wave waveguides.

[0003] Conventionally, as this kind of dielectric porcelain,
For example, ZrO ₂ —SnO ₂ —TiO ₂ based material, BaO—
TiO ₂ -based materials, (Ba, Sr) (Zr, Ti) O ₃ -based materials and Ba (Zn, Ta) O ₃ -based materials are known, and these materials have a frequency of 500 MHz through various improvements.
In the range of z to 5 GHz, the relative dielectric constant is 20 to 40, and the Q value is 10
It has a characteristic in which the temperature coefficient (τf) of the resonance frequency is around 0 ppm / ° C. (Qf = 15000 or less).

[0004]

However, in recent years, the frequency to be used has tended to be higher, and dielectric materials have been required to have more excellent dielectric properties, particularly to improve the Q value. However, at present, the above-mentioned conventional dielectric material does not have a practically high Q value in a used frequency range of 10 GHz.

In recent years, a material having a small relative dielectric constant has been demanded from the viewpoint of workability. However, the above-mentioned conventional dielectric material has a relative dielectric constant of 20 to 30, and from the viewpoint of workability, the dielectric constant is further increased. Materials having a low dielectric constant have been required.

[0006]

Means for Solving the Problems The present inventors have made various studies on the above problems, and as a result, as a metal element, K,
La, Mg and W are contained, and the composition formula based on the molar ratio of these metal element oxides is expressed as x (aKO _1/2 · (1-a) L
aO _3/2 ) · yMgO · zWO ₃ , the above x,
In a dielectric porcelain composition in which y, z and a are predetermined values,
The present inventors have found that the relative permittivity is small, and have a high Q value in a high-frequency region, and the present invention has been achieved.

That is, the dielectric porcelain composition of the present invention contains K, La, Mg and W as metal elements, and the composition formula based on the molar ratio of these metal element oxides is represented by x [aKO
_1/2. (1-a) LaO _3/2 ] .yMgO.zWO ₃ , x, y, z and a are 0.40 ≦ x ≦
0.55, 0.15 ≦ y ≦ 0.30, 0.20 ≦ z ≦
0.30, 0.40 ≦ a ≦ 0.60, x + y + z = 1. Here, (K _1/2 La _1/2 ) (M
g _1/2 W _1/2 ) It is desirable that a perovskite crystal represented by O ₃ be the main crystal phase.

[0008]

According to the present invention, since the relative dielectric constant is as small as 16 or less at a measurement frequency of 10 GHz, it is easy to process porcelain with the accuracy required at high frequencies such as microwaves and millimeter waves, and to measure at 10 GHz. Q value is 1600 or more at frequency (Q
f = 16000 or more) and a high dielectric ceramic composition can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric porcelain composition of the present invention has a composition formula based on the molar ratio of a metal element oxide represented by x [aKO _1/2
· (1-a) LaO _3/2 ] · yMgO · zWO ₃ , x, y, z and a are 0.40 ≦ x ≦ 0.
55, 0.15 ≦ y ≦ 0.30, 0.20 ≦ z ≦ 0.3
0, 0.40 ≦ a ≦ 0.60, x + y + z = 1.

The composition formula x [aKO _1/2 · (1-a) LaO
In _3/2] · yMgO · zWO _3, [aKO _1/2 ·
(1-a) The molar ratio x of [LaO _3/2 ] is 0.40 ≦ x ≦
The reason for setting 0.55 is that when x is smaller than 0.40 or larger than 0.55, sintering becomes poor,
This is because the value decreases. x is preferably from 0.48 to 0.52 from the viewpoint of improving the Q value.

Further, the molar ratio y of MgO is 0.15 ≦ y ≦
The reason for setting 0.30 is that when y is smaller than 0.15, sintering becomes poor or the Q value decreases, and when y is larger than 0.30, the Q value decreases or sintering occurs. This is because it becomes defective. The molar ratio y of MgO is desirably 0.22 to 0.28.

Further, the molar ratio z of WO ₃ is set to 0.20 ≦ z
≦ 0.30 because the Q value decreases when z is smaller than 0.20 or larger than 0.30. The molar ratio z of WO ₃ is desirably 0.22 to 0.28 from the viewpoint of improving the Q value and sinterability.

[0013] In _{addition, aKO 1/2 · (1-a} ) LaO 3/2
The molar ratio a of KO _1/2 and LaO _3/2 represented by
≦ a ≦ 0.60 is because the relative dielectric constant increases when a is smaller than 0.40, and the Q value decreases when a is larger than 0.60. a is
From the viewpoint of high Q value and low relative permittivity, 0.43 to 0.4.
52 is desirable.

In the dielectric porcelain composition of the present invention, from the viewpoint of high Q value and low relative dielectric constant, the composition formula based on the molar ratio of the metal element oxide is represented by x [aKO _1/2 · (1-a) La
O _3/2 ] · yMgO · zWO ₃ , the above x,
y, z and a are 0.48 ≦ x ≦ 0.52, 0.22
≦ y ≦ 0.28, 0.22 ≦ z ≦ 0.28, 0.43 ≦
It is desirable that a ≦ 0.52 and x + y + z = 1 be satisfied.

The dielectric porcelain composition of the present invention has KO _1/2 ,
LaO _3/2, MgO, are those made of WO _3, as a crystal phase _{(K 1/2 La 1/2) (Mg} 1/2 W 1/2) Main crystal perovskite type crystal represented by O ₃ Phase. In other words, the A-site of the perovskite-type crystal is composed of K and La, and the B-site is composed of Mg and W in a ratio of 1: 1 as a main crystal. The average crystal grain size of the main crystal is desirably 3 to 7 μm. still,
In the dielectric porcelain composition of the present invention, (K _1/2 La _1/2 )
As a crystal phase other than (Mg _1/2 W _1/2 ) O ₃ , LaO
_3/2 , La _2/3 (Mg _1/2 W _1/2 ) O ₃ , MgWO _{4 and the} like may be present, but if they are trace amounts, there is no problem in characteristics.

As a method for producing the dielectric ceramic composition of the present invention, first, a raw material powder containing K, La, Mg, and W is prepared. This raw material powder is an oxide containing K, La, Mg, W, an inorganic compound such as a carbonate or an acetate, or an organic compound such as an organic metal. I just want it.

These raw materials are used as KO _1/2 , LaO _3/2 , M
After weighing so as to be within the above range in terms of gO and WO ₃ , the mixture is thoroughly mixed. Then, the mixture is 900-110
Calcinate at 0 ° C and pulverize. Then, a predetermined binder or the like is added to the calcined powder, and the powder is formed into a predetermined shape by a known molding method such as press molding or a doctor blade method. Next, the formed body is placed in an oxidizing atmosphere such as the air at 1200 to 13 m.
By firing at 50 ° C. for 4 to 10 hours, the dielectric ceramic composition of the present invention can be obtained.

In the dielectric ceramic composition of the present invention, Cl, Al, P, Sr, Zr, Y, Ce, Y are inevitable impurities.
In some cases, b, Dy and the like may be mixed, and even if these are mixed in about 0.1% by weight of the total amount, there is no problem in characteristics. Also,
In some cases, metal or the like may be mixed in the crushed balls during crushing.

[0019]

EXAMPLES As raw materials, K ₂ CO ₃ and L having a purity of 99% or more were used.
a ₃ (CO ₃ ) ₂ , MgCO ₃ and WO ₃ powders were used, and these were sintered into KO _1/2 , LaO _3/2 , Mg
O, weighed so as to have the ratio shown in Table 1 in WO ₃ conversion,
Put this together with water in a ball mill lined with rubber,
The mixture was wet mixed with a ZrO ₂ ball for 8 hours. Next, after dehydrating and drying this mixture, it was calcined at 1000 ° C. for 2 hours, and the calcined product was put into a ball mill together with water and an organic binder and wet-ground for 8 hours.

Thereafter, the pulverized material was dried, and then granulated through a No. 50 mesh net.
It was formed into a cylinder having a diameter of 10 mm and a thickness of 5 mm under a pressure of kg / cm ² . Further, the column was fired at 1350 ° C. for 6 hours to obtain a porcelain sample. The porcelain was polished to obtain a sample having a diameter of 8 mm and a thickness of 4 to 5 mm.

With respect to the porcelain sample thus obtained, the relative dielectric constant (εr) and the Q value at a frequency of 10 GHz were measured by a dielectric resonator method, and the TE from 25 ° C. to 85 ° C. was measured.
The temperature coefficient (τf) of the 011 mode resonance frequency is represented by τf =
[(F ₈₅ −f ₂₅ ) / f ₂₅ ] / 60 × 10 ⁶ [ppm /
° C]. Here, f ₈₅ is the resonance frequency at 85 ° C., and f ₂₅ is the resonance frequency at 25 ° C. The results are shown in Table 1.

[0022]

[Table 1]

According to Table 1, Sample No. which is out of the range of the present invention. In Nos. 22 to 26 and 37 to 40, the Q value was 1500 or less, or the relative dielectric constant was large, or sintering failure occurred. On the other hand, the sample No. 1-21,
27 to 36 have a relative dielectric constant of 16 or less, a Q value of 1600 or more (Qf = 16000 or more), and a temperature coefficient of resonance frequency (τ
f) was within the range of ± 6 [ppm / ° C.]. In particular,
When x, y, z and a are 0.48 ≦ x ≦ 0.52, 0.
22 ≦ y ≦ 0.28, 0.22 ≦ z ≦ 0.28, 0.4
Sample No. 1, 27 to 32 satisfying 3 ≦ a ≦ 0.52,
At 34 and 35, the relative dielectric constant is 16 or less and the Q value is 25
00 or more, of which KO _1/2 : LaO _3/2 : Mg
Sample No. 1 in which O: WO ₃ has a ratio of 1: 1: 1: 1
Has a relative dielectric constant of 16 and a Q value of 3000.

X-ray diffraction measurement was performed on the porcelain of Sample No. 1 and the results are shown in FIG. According to FIG. 1, the diffraction peak indicated by a circle indicates that the crystal has a perovskite-type crystal structure, the diffraction peak indicated by a triangle indicates a superlattice structure based on the K-La regular arrangement, and the diffraction peak indicated by a circle indicates Mg-. It is understood that the superlattice structure is based on the regular arrangement of W.

The manufactured dielectric ceramic of the present invention is mostly composed of (K _1/2 La _1/2 ) (Mg _1/2 W _1/2 ) O ₃ crystal grains, and has an average crystal grain size. Was 3 to 7 μm.
In addition, the grain boundary mainly contains La as a crystal phase other than La.
O _3/2 , La _2/3 (Mg _1/2 W _1/2 ) O ₃ , MgWO ₄
Was present in traces.

[0026]

As described above in detail, according to the present invention, a low dielectric constant and a high Q suitable for workability in a high-frequency region.
It can be applied to resonator materials, MIC dielectric substrate materials, capacitor materials, dielectric antenna materials, dielectric waveguide materials, etc. used in the microwave and millimeter wave regions. Can be.

[Brief description of the drawings]

FIG. 1 shows sample Nos. 1 is an X-ray diffraction chart of FIG.

Claims (2)

(57) [Claims] (1) K, La, Mg and W are contained as metal elements, and the composition formula based on the molar ratio of these metal element oxides is represented by x [aKO _1/2. (1-a) LaO _3/2 ]. yMgO ・
When expressed as zWO ₃ , x, y, z and a are 0.40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 0.40 ≦ a ≦ 0 60 x + y + z = 1. 2. (K _1/2 La _1/2 ) (Mg _1/2 W _1/2 ) O
_2. The dielectric ceramic composition according to claim 1, wherein the perovskite crystal represented by ₃ is a main crystal phase.