JP2001072464A - Dielectric ceramic composition and dielectric resonator using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric ceramic composition having both high dielectric constant and high Q-value in high-frequency region, with its temperature coefficient τf of resonance frequency controllable stably to low levels. SOLUTION: This dielectric ceramic composition contains at least La, Al, Sr and Ti as metallic elements, having the compositional formula aLa2O3.bAl2 O3.cSrO.dTiO2; wherein the parameters a, b, c and d are adjusted so as to meet the following ranges, respectively (where a+b+c+d=1):0.0954<=a<=0.1596, 0.0954<=b<=0.1596, 0.3903<=c<=0.5516 and 0.2129<=d<=0.3546, and also 0.8181<=b/a<=1.2222 and 0.4285<=d/c<0.7500.

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 high Q value in a high frequency range such as a microwave and a millimeter wave, and is used in a high frequency range such as a microwave and a millimeter wave. The present invention relates to a dielectric ceramic composition which can be used for various resonator materials, a dielectric substrate material for MIC (Monolithic IC), a dielectric waveguide material, a multilayer ceramic capacitor, and the like.

[0002]

2. Description of the Related Art Dielectric ceramics are widely used in dielectric resonators, MIC dielectric substrates, waveguides, and the like in high-frequency regions such as microwaves and millimeter waves. The required characteristics are (1) Since the wavelength is reduced to 1 / εr ^1/2 in a dielectric, a large relative dielectric constant is required for miniaturization, and (2) Dielectric loss at high frequencies Is small, that is, high Q
(3) the change in resonance frequency with respect to temperature is small, that is, the temperature dependency of the relative dielectric constant is small and stable.

Conventionally, as this type of dielectric porcelain, for example, a Ba (Mg _1/3 Ta _2/3 ) O ₃ material (Japanese Patent Publication No. _59-59 )
No. 23048), Ba (Zn _1/3 Ta _2/3 ) O ₃ material (JP-B-59-48484), Ba (Zn _1/3 Nb)
_2/3 ) O ₃ material (JP-B-53-35453), Ba
(Mg _1/3 Nb _2/3 ) O ₃ -based material (JP-A-53-353)
Oxide porcelain materials such as 45) are known.

[0004]

However, recently, the frequency range to be used has been further increased, and accordingly, a material having a higher Q value has been demanded. From this, it can be seen that the conventional dielectric porcelain composition has a small unloaded Q and a small relative dielectric constant, so that the shape when formed into a resonator is large, and the temperature coefficient is large, and the microwave coefficient is large. There are some difficulties in using them in the frequency band, and there are many disadvantages in actual use. In addition, these materials have a problem that the firing temperature is high and the firing cost is high, and the materials themselves are expensive because they contain Ta and Nb. .

The present invention has been made in view of the above-mentioned drawbacks, and has a large relative dielectric constant, a high Q value, a small temperature dependence of the relative dielectric constant, and is stable. A dielectric porcelain composition is provided.

[0006]

Means for Solving the Problems The present inventor has repeatedly studied the above problem and found that at least L
By containing a, Al, Sr, and Ti and adjusting them to a specific range, the relative dielectric constant is large, the Q value is high,
It has been found that a dielectric ceramic composition having a small temperature dependence of the relative dielectric constant and being stable can be obtained.

That is, the dielectric porcelain composition of the present invention contains at least La, Al, Sr, and Ti as metal elements, and the composition formula based on the molar ratio of these metal elements is aLa _2.
When expressed as _{O 3 · bAl 2 O 3 ·} cSrO · dTiO 2, wherein a, b, c, d, but, 0.0954 ≦ a ≦ 0.1596 0.0954 ≦ b ≦ 0.1596 0.3903 ≦ Within a composition range expressed as c ≦ 0.5516 0.2129 ≦ d ≦ 0.3546 0.8181 ≦ b / a ≦ 1.2222 0.4285 ≦ d / c <0.7500 (where a + b + c + d = 1) There is a feature.

In addition, at least La, A
l, when containing Sr and Ti, showing the composition formula by molar ratio of these metal elements and _{aLa 2 O 3 · bAl 2 O} 3 · cSrO · dTiO 2, wherein a, b, c and d are 0. 0954 ≦ a ≦ 0.1596 0.0954 ≦ b ≦ 0.1596 0.3903 ≦ c ≦ 0.5516 0.2129 ≦ d ≦ 0.3546 0.8181 ≦ b / a ≦ 1.2222 0.4285 ≦ d /C≦0.7500 (where a + b + c + d = 1) and 100 parts by weight of the main component,
Mn is 3.0 parts by weight or less in terms of MnO ₂ , or W is WO
Equivalent to ₃ 5.0 parts by weight or less, or Mo, characterized in that it contains more than 5.0 parts by weight calculated as MoO _3.

Further, at least La, A as a metal element
l, Sr, containing Ti, when the composition formula by molar ratio of the metal elements expressed as _{aLa 2 O 3 · bAl 2 O} 3 · cSrO · dTiO 2, wherein a, b, c, d, but 0 0.0954 ≦ a ≦ 0.1596 0.0954 ≦ b ≦ 0.1596 0.3903 ≦ c ≦ 0.5516 0.2129 ≦ d ≦ 0.3546 0.8181 ≦ b / a ≦ 1.2222 0.4285 ≦ With respect to a main component satisfying d / c ≦ 0.7500 (a + b + c + d = 1) and 100 parts by weight of the main component,
Mn, W, and Mo are contained in an amount of 6.0 parts by weight or less in terms of MnO ₂ , WO ₃ , and MnO ₃ .

In the dielectric resonator according to the present invention, a dielectric porcelain is disposed between a pair of input / output terminals, and the dielectric porcelain operates by electromagnetic field coupling. It comprises a dielectric ceramic composition for use.

According to the present invention, the relative permittivity εr
Is large, the Q value is high, the absolute value of the temperature coefficient τf of the resonance frequency is small, the values of εr, Q, τf can be controlled stably, and materials containing expensive elements such as Ta and Nb can be used. Without using it, it becomes an inexpensive dielectric ceramic composition and dielectric resonator.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The high frequency dielectric ceramic composition of the present invention comprises a composite oxide containing at least La, Al, Sr and Ti as metal elements as a main component composition. When the composition formula based on the molar ratio of the metal element in such a main component composition is expressed as aLa ₂ O ₃ .bAl ₂ O ₃ .cSrO.dTiO ₂ , a, b, c, and d are 0.0954 ≦ a ≦ 0.1596 0.0954 ≦ b ≦ 0.1596 0.3903 ≦ c ≦ 0.5516 0.2129 ≦ d ≦ 0.3546 0.8181 ≦ b / a ≦ 1.2222 0.4285 ≦ d / c <0 0.7500 (where a + b + c + d = 1). The reasons for limiting a, b, c, and d to the above ranges are as follows.

That is, the reason for setting 0.0954 ≦ a ≦ 0.1596 is that when a <0.0954, the temperature coefficient τf of the resonance frequency becomes positive and the temperature coefficient τf of the resonance frequency becomes large.
This is because the absolute value of f greatly exceeds 30.
If> 0.1596, τf becomes large negatively, and its absolute value exceeds 30. Especially 0.12
The range of 11 ≦ a ≦ 0.1369 is preferable.

Further, the reason for setting 0.0954 ≦ b ≦ 0.1596 is that when b <0.0954, the temperature coefficient τf of the resonance frequency becomes positive and the absolute value of τf greatly exceeds 30, When b> 0.1596, the resonance frequency τf
Becomes negative and the absolute value of τf exceeds 30. b is, in particular, 0.1211 ≦ b ≦ 0.136
A range of 9 is preferred.

Further, 0.3903 ≦ c ≦ 0.5516
The reason is that when c <0.3903, the temperature coefficient τf of the resonance frequency becomes negative and the absolute value of τf greatly exceeds 30. When c> 0.5516, the temperature coefficient τf of the resonance frequency becomes positive, and
This is because the absolute value exceeds 30. In particular,
The range of 0.4284 ≦ c ≦ 0.4698 is preferable.

Further, the condition of 0.2129 ≦ d ≦ 0.3546 is that when d <0.2129, the resonance frequency
This is because the temperature coefficient τf becomes negative and its absolute value exceeds 30. When d> 0.3546, the temperature coefficient τf of the resonance frequency becomes positive and its absolute value exceeds 30. It is because. In particular, 0.2759
≦ d ≦ 0.3107 is preferred.

Furthermore, 0.8181 ≦ b / a ≦ 1.22
22 is set when b / a <0.8181 or when b / a <0.8181.
In the case of a> 1.2222, Qf greatly decreases and 4
This is because it is lower than 0000. In particular, 0.9602
≦ b / a ≦ 1.1744 is preferred.

Also, 0.4285 ≦ d / c <0.750
0 was set when d / c <0.4285.
This is because when the electric conductivity εr decreases and d / c ≧ 0.7500, τf increases positively and its absolute value exceeds 30. In particular, 0.6129 ≦ d / c ≦ 0.6
949 is preferred.

Furthermore, 0.8181 ≦ b / a ≦ 1.22
22 and 0.4285 ≦ d / c <0.7500
The reason is that τf can be adjusted near 0 in this range.

Further, the present invention improves the Q value only without changing εr or τf by adding 3.0 parts by weight or less of Mn in terms of MnO _{2 with} respect to 100 parts by weight of the main component. It can be done. The reason that the content of Mn was set to 3.0 parts by weight or less in terms of MnO ₂ was 3.0.
This is because when the amount exceeds the weight part, the Q value becomes extremely small.
Further, in order to achieve the above-described effects, the amount of Mn is changed to Mn.
It is preferably 0.01 to 3.0 parts by weight in terms of O ₂ , particularly preferably 0.1 to 1.0 part by weight.

Further, the present invention is, with respect to the 100 parts by weight of the main component, by the inclusion of 5.0 parts by weight or less W in terms _of WO _3, it is possible to improve the Q value. The content of W is set to 5.0 parts by weight in terms of WO ₃ because the Q value becomes extremely small when it exceeds 5.0 parts by weight. Furthermore, in order to achieve the effect described above, it is desirable that 0.01 to 5.0 parts by weight the amount of W in terms _of WO _3, it is desirable to particularly 0.1 to 2.0 parts by weight.

In the present invention, the Q value can be improved by adding 5.0 parts by weight or less of Mo in terms of MoO _{3 with} respect to 100 parts by weight of the main component. The reason why the Mo content is set to 5.0 parts by weight or less in terms of MoO ₃ is that if the content exceeds 5.0 parts by weight, the Q value becomes extremely small. Furthermore, in order to achieve the effect described above, it is desirable that 0.01 to 5.0 parts by weight of Mo calculated as MoO _3, it is desirable to particularly 0.1 to 2.0 parts by weight.

Each of the above components of Mn, W, and Mo may contain one or more of them. When all of these components are contained, the Q value can be improved by including a total of 6.0 parts by weight or less in terms of MnO ₂ , WO ₃ , and MoO _{3 with} respect to 100 parts by weight of the main component. . The content of Mn, W, and Mo was changed to MnO
_{2. The} reason why the content is not more than 6.0 parts by weight in terms of WO ₃ and MnO ₃ is that if it exceeds 6.0 parts by weight, the Q value becomes extremely small. Further, in order to achieve the above-described effects, Mn
The content is preferably 0.01 to 6.0 parts by weight, particularly 0.1 to 2.0 parts by weight in terms of O ₂ , WO ₃ and MnO ₃ .

The dielectric ceramic composition of the present invention is produced, for example, as follows. As starting materials, high-purity lanthanum oxide, aluminum oxide, strontium carbonate, and titanium oxide powders were weighed so as to have a desired ratio, and pure water was added.
Wet mixing and pulverization are performed by a mill using zirconia balls or the like for 10 to 30 hours until the particle size becomes not more than μm. After the mixture is dried, it is calcined at 1000 to 1300 ° C. for 2 to 10 hours, and granulated after further adding 5% by weight of a binder, and the obtained powder is subjected to desired molding means, for example, die pressing, cold pressing. It is obtained by forming into an arbitrary shape by isostatic pressing, extrusion molding or the like, and then firing in the air at a temperature of 1500 to 1700 ° C. for 1 to 10 hours.

In the dielectric porcelain composition of the present invention, L
a, Al, Sr, Ti starting materials
In addition, a compound that can generate an oxide by heat treatment in an oxidizing atmosphere, such as a carbonate, an acetate, a nitrate, or a hydroxide, may be used.

In the present invention, Ca, Zr, Si, Ba, and the like may be mixed as unavoidable impurities into the porcelain.
Even if it is mixed in about 1% by weight, there is no problem in characteristics.

The above-mentioned dielectric ceramic composition of the present invention is most useful for a dielectric resonator. As a dielectric resonator of the present invention, a schematic diagram of the TE mode dielectric resonator of FIG. 1 is shown. In the resonator shown in FIG. 1, an input terminal 2 and an output terminal 3 are formed on both sides of a metal case 1, and a dielectric porcelain 4 having the above-described composition is arranged between these terminals 2, 3. Be composed. As described above, in the TE mode dielectric resonator, the microwave is input from the input terminal 2 and the microwave is confined in the dielectric ceramic 4 by reflection at the boundary between the dielectric ceramic 4 and free space. Causes resonance at a specific frequency.

This signal is electromagnetically coupled to the output terminal 3 and output. Although not shown, the present invention is applied to a coaxial resonator, a strip line resonator, a TM mode dielectric ceramic resonator, and other resonators using the dielectric ceramic composition TEM mode of the present invention. Of course, it is also good.

[0029]

Example 1 High-purity lanthanum oxide (La ₂ O ₃ ) as a starting material
Using each powder of aluminum oxide (Al ₂ O ₃ ), strontium carbonate (SrCO ₃ ), and titanium oxide (TiO ₂ ), weighing them as shown in Table 1, and adding pure water,
The mixture was wet-mixed and pulverized for about 20 hours by a mill until the average particle size of the mixed raw material became 2.0 μm or less. Note that ZrO ₂ and S
1% by weight of total impurities of iO ₂ and other rare earth elements
The following may be contained.

After the mixture is dried, it is calcined at 1200 ° C. for 2 hours, and about 5% by weight of a binder is added.
The obtained powder was granulated, formed into a disk at a pressure of about 1 ton / cm ² , and fired in the air at a temperature of 1500 to 1700 ° C. for 2 hours.

The disk portion of the obtained porcelain was polished flat, ultrasonically washed in acetone, and dried at 150 ° C. for 1 hour.
The relative permittivity εr, the Q value, and the temperature coefficient τf of the resonance frequency were measured at a measurement frequency of 3.5 to 4.5 GHz by a cylindrical resonator method. The Q value is determined by the following formula: Q value generally established in microwave dielectric × measurement frequency f = Q at 1 GHz from a fixed relation.
It was converted to a value.

The temperature coefficient τf of the resonance frequency is -40 to 8
It was measured in the range of 5 ° C.

[0033]

[Table 1]

Example 2 High-purity lanthanum oxide (La ₂ O ₃ ) as a starting material
Using each powder of aluminum oxide (Al ₂ O ₃ ), strontium carbonate (SrCO ₃ ), and titanium oxide (TiO ₂ ), weighing them as shown in Table 2, and adding pure water,
The mixture was wet-mixed and pulverized for about 20 hours by a mill until the average particle size of the mixed raw material became 2.0 μm or less.

After drying this mixture, it was calcined at 1200 ° C. for 2 hours. With respect to 100 parts by weight of the calcined powder, MnO ₂ ,
After adding WO ₃ and MoO ₃ in the amounts shown in Table 2, pure water was added until the average particle size of the mixed raw material became 2.0 μm or less.
The mixture was wet-mixed and pulverized for about 20 hours by a mill. After drying, about 5% by weight of a binder was further added, followed by granulation.

The obtained powder was formed into a disk at a pressure of about 1 ton / cm ² and fired in the air at a temperature of 1500 to 1700 ° C. for 2 hours.

The disk portion of the obtained porcelain was polished flat, ultrasonically cleaned in acetone, and dried at 150 ° C. for 1 hour.
The relative permittivity εr, the Q value, and the temperature coefficient τf of the resonance frequency were measured at a measurement frequency of 3.5 to 4.5 GHz by a cylindrical resonator method. The Q value is determined by the following formula: Q value generally established in microwave dielectric × measurement frequency f = Q at 1 GHz from a fixed relation.
It was converted to a value.

The temperature coefficient τf of the resonance frequency is -40 to 8
It was measured in the range of 5 ° C.

[0039]

[Table 2]

As is clear from Tables 1 and 2, dielectrics outside the range of the present invention had low relative permittivity or Q value, or had an absolute value of τf exceeding 30.

On the other hand, the dielectric obtained by the present invention has a Q value of 70,000 or more and a τf of ± 30 (ppm /
It was found that excellent dielectric properties within (° C) were obtained.

[0042]

As described in detail above, according to the present invention, at least La, Al, Sr, and Ti are contained as metal elements, and the composition formula based on the molar ratio of these metal elements is aLa _2.
When expressed as O ₃ · bAl ₂ O ₃ · cSrO · dTiO ₂ , the a, b, c, and d are 0.0954 ≦ a ≦ 0.1596 0.0954 ≦ b ≦ 0.1596 0.3903 ≦ c ≦ 0.5516 0.2129 ≦ d ≦ 0.3546 0.8181 ≦ b / a ≦ 1.2222 and 0.4285 ≦ d / c <0.7500 (where a + b + c + d = 1) By adjusting, also
By adding Mn, W, and Mo to this main component, a high dielectric constant εr has a high Q value in the vicinity of 30 in a high frequency region, and the temperature coefficient τf of the resonance frequency is stably controlled to be close to 0. Was completed.

Further, it is possible to provide a less expensive material as compared with a conventional dielectric ceramic composition containing Ta, Nb or the like as a constituent element. In addition, the existing material composed of Ta and Nb has a high firing temperature at a high temperature unless the firing temperature is maintained for a long time. If the firing temperature is maintained for 2
In 10 hours, the firing cost can be greatly reduced.

Thus, the dielectric porcelain composition of the present invention can be used as a material for a resonator used in a microwave or millimeter wave region in a device such as an automobile telephone, a cordless telephone, a personal wireless device, a satellite broadcast receiver, and the like. And M
The present invention can be suitably applied to a dielectric substrate material for an IC, a dielectric waveguide, a dielectric antenna, and other various electronic components.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a dielectric resonator of the present invention.

[Explanation of symbols]

 1. Metal case 2. Input terminal 3. Output terminal 4. Dielectric porcelain

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01P 7/10 H01P 7/10

Claims (4)

[Claims] 1. At least La, Al, S as a metal element
containing r and Ti, when the composition formula by molar ratio of the metal elements expressed as _{aLa 2 O 3 · bAl 2 O} 3 · cSrO · dTiO 2, wherein a, b, c, and d is 0.0954 ≤a≤0.1596 0.0954≤b≤0.1596 0.3903≤c≤0.5516 0.2129≤d≤0.3546 0.8181≤b / a≤1.2222 0.4285≤d / c <0.7500 (where a + b + c + d = 1). 2. At least La, Al, S as a metal element
r and Ti, and when the composition formula based on the molar ratio of these metal elements is expressed as aLa ₂ O ₃ .bAl ₂ O ₃ .cSrO.dTiO ₂ , a, b, c, and d are 0.0954 ≤a≤0.1596 0.0954≤b≤0.1596 0.3903≤c≤0.5516 0.2129≤d≤0.3546 0.8181≤b / a≤1.2222 0.4285≤d / With respect to a main component satisfying c ≦ 0.7500 (a + b + c + d = 1) and 100 parts by weight of the main component,
Mn is 3.0 parts by weight or less in terms of MnO ₂ , or W is WO
_3. A dielectric porcelain composition containing not more than 5.0 parts by weight in terms of ₃ or not more than 5.0 parts by weight of Mo in terms of MoO3. 3. At least La, Al, S as a metal element
When the composition formula based on the molar ratio of these metal elements is represented by aLa ₂ O ₃ .bAl ₂ O ₃ .cSrO.dTiO ₂ , the a, b, c and d are 0.0954. ≤a≤0.1596 0.0954≤b≤0.1596 0.3903≤c≤0.5516 0.2129≤d≤0.3546 0.8181≤b / a≤1.2222 0.4285≤d / With respect to a main component satisfying c ≦ 0.7500 (a + b + c + d = 1) and 100 parts by weight of the main component,
Mn, MnO ₂ W and Mo, WO _3, MoO ₃ dielectric ceramic composition characterized by containing the following total 6.0 parts by weight basis. 4. A resonance medium comprising the dielectric ceramic composition according to claim 1 is disposed between a pair of input / output terminals, and a high-frequency signal is applied between the input / output terminals to obtain a desired medium. A dielectric resonator characterized by resonating at a frequency.