JP2000044338A - Dielectric ceramic composition and dielectric resonator produced by using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition for high-frequency use, having high Q-value in high-frequency range and exhibiting suppressed lowering of Q-value at high temperature (120 deg.C) compared with the Q-value at normal temperature (25 deg.C). SOLUTION: The objective composition is produced by adding <=3 pts.wt. of Mn to 100 pts.wt. of main component having a composition expressed by x ((1-a)BaO.aSrO).y (1-b)MgO.bAO}.zWO3 (A is at least one kind of element selected from iron group metals and Zn) and satisfying the formulas 0<a<1, 0.01<=b<=0.7, 0.40<=x<=0.55, 0.15<=y<=0.30, 0.20<=z<=0.30 and x+y+z=1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric ceramic composition having a high relative dielectric constant and a high Q value in a high frequency region such as microwaves and millimeter waves.
For example, a dielectric ceramic composition that can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, multilayer ceramic capacitors, and the like used in high frequency regions such as microwaves and millimeter waves. It is about things.

[0002]

2. Description of the Related Art Hitherto, dielectric ceramics have been widely used for 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. The characteristics required therefor are as follows: (1) In a dielectric, the wavelength is 1 /
Since it is reduced to √εr, the relative permittivity is large for the demand for miniaturization, (2) the dielectric loss at high frequency is small, that is, a high Q value, and (3) the temperature of the resonance frequency is The main characteristics are that the change is small and the above three characteristics.

[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. However, recently, the frequency to be used tends to be higher and the dielectric material is required to have more excellent dielectric properties, particularly to improve the Q value.

However, the conventional dielectric materials described above do not have a practically high Q value at a high frequency, for example, a working frequency range of 10 GHz.

On the other hand, recently, as a composition having a high relative dielectric constant and a high Q value in a high frequency region, Ba
Dielectric porcelain composition comprising a composite oxide containing O, MgO and WO ₃ and dielectric porcelain composition comprising a composite oxide containing SrO, MgO and WO ₃ (JP-A-5-20
No. 5524, Japanese Patent Application Laid-Open No. 6-5117).
A composition comprising O, SrO, MgO, and WO ₃ was prepared,
On the other hand, by including at least one kind of cobalt (Co), nickel (Ni), zinc (Zn) or the like in a predetermined amount, a high Q value can be obtained, and the temperature coefficient of the resonance frequency ( It has been proposed that τf) can be shifted from the negative side to the positive side.

[0006]

In this dielectric porcelain composition, the temperature coefficient (τf) of the resonance frequency can be freely controlled by changing the molar ratio of Ba0 and SrO, and cobalt (Co) By containing a predetermined amount of at least one of nickel, nickel (Ni) and zinc (Zn), a high porcelain density can be realized and a high Q value can be obtained.

However, this dielectric porcelain composition has
Although a high Q can be obtained in a high frequency region, defects occur inside the porcelain due to a change in the valence of W, evaporation of Zn or the like, and the Q value tends to decrease, and the Q value at high temperature (120 ° C.) , Significantly lower than the Q value at normal temperature (25 ° C),
There has been a problem that the merits of the high Q value cannot be sufficiently enjoyed.

[0008]

The present inventors have made various studies on the above problems and found that BaO, SrO, M
gO, WO ₃ against cobalt (Co), nickel (N
i), by adding a predetermined amount of MnO ₂ to a composition containing at least one kind of zinc (Zn) or the like, Q
The present inventors have found that the value can be stabilized and a decrease in the Q value at a high temperature (120 ° C.) can be reduced, and the present invention has been achieved.

That is, the high frequency dielectric ceramic composition of the present invention contains at least Ba, Sr, Mg and W as metal elements, and a composition formula based on a molar ratio of these metal element oxides is expressed as x ｛(1 −a) BaO · aSrO｝ · y ｛(1
-B) When expressed as MgO · bAO｝ · zWO ₃ (A is at least one of iron group metals and Zn),
b, x, y and z are 0 <a <1, 0.01 ≦ b ≦
0.7, 0.40 ≦ x ≦ 0.55, 0.15 ≦ y ≦ 0.
30, 100 parts by weight of the main component in the range of 0.20 ≦ z ≦ 0.30, x + y + z = 1, containing 3 parts by weight or less of Mn in terms of MnO ₂ .

[0010] The dielectric ceramic composition of the present invention have the general formula _{(Ba 1-a Sr a)} {(Mg 1-b A b) 1/2 W 1/2} O
₃ (0 <a <1, 0.
(01 ≦ b ≦ 0.7) is the main crystal phase, and it is preferable that all or a part of Mn be dissolved.

Here, the reason why the substitution amount a of BaO by SrO is set to 0 <a <1 is that when a = 0 or 1, a solid solution of Ba and Sr is not obtained, and the temperature coefficient (τf) of the resonance frequency is controlled. This is because the effect cannot be obtained. The reason why the substitution amount b of MgO with the iron group metal and Zn is 0.01 ≦ b ≦ 0.7 is that when b is less than 0.01, the effect of lowering the firing temperature and improving the porcelain density is almost obtained. This is because when the ratio is more than 0.7, the Q value is significantly reduced. This b is 0.01 ≦ b from the viewpoint of obtaining a higher porcelain density and a higher Q value.
It is desirable that ≦ 0.65. As iron group metals,
There are Fe, Ni, and Co. Among them, Ni, Co
Is desirable.

Furthermore, the reason why the composition ratio is limited to the above range for each of a and b is that the effect of solid solution is insufficient outside the above range, or the sinterability is lowered or the Q value is lowered. This is because a problem of lowering occurs.

That is, when the molar ratio x is 0.40 ≦ x ≦ 0.55
This is because the Q value decreases when the value is smaller than 0.40 or larger than 0.55. x
Is preferably 0.49 ≦ x ≦ 0.52 from the viewpoint of improving the Q value.

Further, the molar ratio of MgO is 0.15 ≦ y ≦
The reason for setting the value to 0.30 is that when y is smaller than 0.15, the Q value decreases, and when y is larger than 0.30, the Q value decreases or sintering becomes poor. The molar ratio y of MgO is 0.20 ≦ M from the reason of improvement of Q value and sinterability.
It is desirable that y ≦ 0.27.

Further, the molar ratio of WO ₃ is set to 0.20 ≦ z ≦
The reason for setting the value to 0.30 is that when z is smaller than 0.20, sintering becomes defective, and when z is larger than 0.30, the Q value decreases. The molar ratio z of WO ₃ is preferably 0.22 ≦ z ≦ 0.28 from the viewpoint of improving the Q value and sinterability.

Further, the present invention is characterized in that the dielectric ceramic composition contains MnO ₂ in an amount of 3 parts by weight or less based on 100 parts by weight of the main component.

That is, by adding Mn to the main component, the Q value can be stabilized without changing εr and τf, and the decrease in the Q value at high temperatures can be suppressed. Further, the reason that the content of Mn is 3 parts by weight or less in terms of MnO ₂ is that if it exceeds 3 parts by weight, the Q value becomes extremely small, and τf shifts to the + side.
Further, the content of Mn must not be 0 parts by weight, and in order to achieve the above-described effects, the content of Mn must be MnO ₂
Desirably, it is 0.01 parts by weight or more in terms of conversion.

The dielectric porcelain composition of the present invention is produced, for example, as follows. Prepare an oxide of Ba, Sr, Mg, W or a metal salt such as a carbonate or a nitrate which generates an oxide by firing as a main raw material, weigh them to the above-mentioned range, and mix them sufficiently. . Then, it is calcined at 900 to 1200 ° C. in the atmosphere for 1 to 4 hours. To the obtained calcined product, for example, each compound of a cobalt compound such as CoO, a nickel compound such as NiO, and a zinc compound such as ZnO is weighed to a predetermined amount and added, and MnO ₂ is further added. Add a fixed amount and mix and grind. Then, this is molded into a predetermined shape by a molding method such as press molding or a doctor blade method. Next, the molded body is heated to 1300 ° C. to 1450 ° C. in an oxidizing atmosphere such as the air.
For 1 to 8 hours to obtain a dielectric porcelain.

In the present invention, C is used as an unavoidable impurity.
l, Ca, Zr, etc. may be mixed, and Cl, C
Even if a, Zr, etc. are mixed in an amount of about 0.1% by weight in terms of oxide, there is no problem in characteristics. In particular, for the dielectric composition, Al
Since the presence of each element of Y and Y tends to increase the firing temperature, according to the present invention, the amounts of these metal elements are:
It is desirable to control so that the content is 5% by weight or less of the total amount in terms of oxide, including impurities.

[0020] In the present invention, in order to increase the Q value, the formula _{(Ba 1-a Sr a)} {(Mg 1-b A b)
Perovskite crystal represented by _1/2 W _1/2 ｝ O ₃ (0
It is preferable that <a <1, 0.01 ≦ b ≦ 0.7) be the main crystal. However, even if a small amount of crystals such as BaWO ₄ and SrWO ₄ are present, there is almost no problem in characteristics. Further, it is preferable that Mn is entirely or partially dissolved in the main crystal.

Further, the present invention is characterized in that the dielectric ceramic composition is arranged between a pair of input / output terminals to constitute a dielectric resonator.

That is, the dielectric resonator of the present invention has, for example,
As shown in FIG. 1 showing a TE mode resonator, a metal case 1 is shown.
An input terminal 2 and an output terminal 3 are formed on both sides of the ceramic material, and a ceramic body 4 of a dielectric ceramic composition having the above-described composition is arranged between these terminals 2 and 3. As described above, the TE mode dielectric resonator has the input terminal 2
, And is confined in the ceramic body 4 by reflection at the boundary between the ceramic body 4 and free space, and resonates at a specific frequency. This signal is electromagnetically coupled to the output terminal 3 and output.

Although not shown, the dielectric ceramic composition of the present invention can be used for a coaxial resonator, a stripline resonator using a TEM mode, a TM mode dielectric resonator, and other resonators. Needless to say, it may be applied to

[0024]

The dielectric porcelain composition of the present invention contains at least Ba, Sr, Mg, and W as metal elements, and the composition formula based on the molar ratio of these metal element oxides is x ｛(1
-A) BaO.aSrO｝ .y ｛(1-b) MgO.b
When expressed as AO｝ · zWO ₃ (A is at least one of iron group metals and Zn), a predetermined Mn is contained therein, so that a stable Q value is exhibited, and Q at high temperature (120 ° C.)
A dielectric porcelain composition that can reduce the decrease in the value can be obtained.

[0025]

EXAMPLES As raw materials, BaCO ₃ and S having a purity of 99% or more were used.
rCO _3, MgCO _3, CoO (or NiO or ZnO,) and, using the powder of WO _3, it was weighed to a ratio shown in Table 1 to Table 2, which were placed with IPA in a ball mill lined with rubber And wet mixing using a ZrO ₂ ball for 8 hours. Next, the mixture was desolvated and dried, and then calcined in the air at 1000 ° C. for 2 hours. MnO ₂ was added to the calcined product, and I was added to a ball mill.
PA was added and wet milled for 8 hours using ZrO ₂ balls.

Thereafter, the pulverized product was dried, an organic binder was added, and the mixture was granulated through a No. 40 mesh net.
The obtained powder was compressed at a pressure of 1000 kg / cm ^{2 to} a diameter of 12
It was formed into a cylinder having a thickness of 6 mm and a thickness of 6 mm. Further, the column was fired in the atmosphere at 1300 to 1600 ° C. for 2 to 6 hours to obtain a porcelain. The porcelain was polished to obtain a sample having a diameter of 8 mm and a thickness of 4 to 5 mm.

The porcelain density of the obtained sample was measured by the Archimedes method. The frequency is about 10-11GHz
Was measured by the dielectric resonator method, and the Q value was converted to a Q value at 10 GHz, assuming that the general formula Qf = constant. Also 25
The temperature coefficient (τf) of the TE011 mode resonance frequency at each temperature from ° C to 85 ° C was calculated. Furthermore, regarding the Q value, the Q value at 120 ° C. was also measured, and the room temperature (25 ° C.)
(° C.) was calculated as the rate of decrease.

The results are shown in Tables 1 and 2.

[0029]

[Table 1]

[0030]

[Table 2]

From this table, it can be seen that the high frequency dielectric ceramic composition of the present invention has a higher Q value and is more stable than the conventional example by adding Mn, and also has a high temperature (120 ° C.) at room temperature (25 ° C.). It can be seen that the rate of decrease of the Q value with respect to

Incidentally, the obtained porcelain was subjected to X-ray diffraction measurement. As a result, the sample of the present invention was found to have the general formula (Ba _{1 -a} S
r _a ) ｛(Mg _{1 -b Ab} ) _1/2 W _1/2 ｝ O ₃ perovskite crystal (0 <a <1, 0.01 ≦ b ≦
0.7) was confirmed to be the main crystal phase. Further, M
The fact that n is in solid solution can be confirmed by using TEM,
Was confirmed to exist. In addition, it was confirmed that part of Mn was also present at the grain boundaries.

[0033]

According to the dielectric ceramic composition for high frequency waves of the present invention, the main component consisting of BaO, SrO, MgO and WO ₃ contains a predetermined amount of an iron group metal and zinc, so that the temperature coefficient of resonance frequency (τf ) Can be easily controlled, a high Q value can be stabilized by adding a predetermined amount of MnO ₂ , and further, a decrease in the Q value at a high temperature (120 ° C.) can be suppressed, and the Q value at 10 GHz can be controlled. Can be as high as 3000 or more.

The porcelain thus obtained is sufficient for a resonator material, a dielectric substrate material for MIC, a material for a capacitor, a material for a dielectric antenna, a material for a dielectric waveguide used in a microwave or millimeter wave region. Can be applied.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a dielectric resonator of the present invention.

[Explanation of symbols]

 1: metal case 2: input terminal 3: output terminal 4: resonance medium

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G030 AA07 AA09 AA10 AA24 AA25 AA27 AA32 BA09 CA01 GA04 GA20 GA22 GA25 GA27 5G303 AA02 AA05 AA10 AB08 AB11 AB20 BA12 CA01 CB03 CB17 CB18 CB32 CB37 5J006 HC07 LA14

Claims (3)

[Claims] At least Ba, Sr, M as a metal element
g and W, and the composition formula based on the molar ratio of these metal element oxides is expressed as x {(1-a) BaO.aSrO} .y {(1-b) M
When expressed as gO · bAO｝ · zWO ₃ (A is at least one of iron group metals and Zn), a, b, x, y and z are 0 <a <1 0.01 ≦ b ≦ 0.7 0.40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 MnO _{2 with} respect to 100 parts by weight of the main component in the range of x + y + z = 1
A dielectric porcelain composition characterized by containing 3 parts by weight or less of Mn in conversion. Wherein the general formula _{(Ba 1-a Sr a)} {(Mg 1-b A
_b ) A main crystal phase is a perovskite crystal (0 <a <1, 0.01 ≦ b ≦ 0.7) represented by _1/2 W _1/2 ｝ O ₃ , and all or a part of Mn is solid. The dielectric ceramic composition according to claim 1, wherein the composition is dissolved. 3. A high frequency signal is applied between a pair of input terminals provided on a resonator medium having a predetermined shape with the dielectric ceramic composition according to claim 1 so as to resonate at a desired frequency. A dielectric resonator characterized in that: