JP2000203934A - Dielectric porcelain composition for high frequency and dielectric resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric porcelain composition for a high frequency, which has a high relative dielectric constant, high Q value and small temp. dependence of the relative dielectric constant and, further, is capable of maintaining high retentivity of Q-value at 120 deg.C based on the room temp. (25 deg.C), and a dielectric resonator. SOLUTION: The formula, based on molar ratio of metal elements, of the composition of main components is expressed by aLa2O3.bAl2O3.cSrO.dTiO2, wherein a, b, c and d satisfy the following relations; 0.1061<=a<=0.2162, 0.1050<=b<=0.2086, 0.3040<=c<=0.4185, 0.2747<=d<=0.4373, 0.75<=b/a<=1.25, 0.75<=d/c<=1.25 (a+b+c+d=1). The dielectric porcelain composition for a high frequency contains Mn in an amount of 0.01-3.0 parts by weight expressed in term of MnO2 per 100 parts by weight of the composition of the main components.

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 and a dielectric resonator having a high Q value in a high frequency region such as a microwave and a millimeter wave. High frequency dielectric ceramic composition and dielectric resonance which can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, multilayer ceramic capacitors, etc. used in high frequency regions such as waves. About the vessel.

[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 the dielectric, the relative dielectric constant is large for the demand for miniaturization, and (2) the dielectric loss at high frequencies Are small, that is, a high Q value, and (3) the change in resonance frequency with respect to temperature is small and stable.

Conventionally, as this kind of dielectric porcelain, for example, BaO-TiO ₂ material, BaO-REO-TiO
₂ (However, REO is a rare earth oxide) based material, MgT
iO ₃ oxide ceramic materials such as -CaTiO ₃ based materials are known (e.g., JP 61-10806, JP-
See JP-A-63-100058).

[0004]

SUMMARY OF THE INVENTION However, BaO
-TiO ₂ -based material has a relative dielectric constant εr of as high as 37 to 40 and a Q value of as large as 40000, but it is difficult to obtain a single phase having a temperature dependence τf of resonance frequency of 0, and the relative dielectric constant with respect to composition change The change in the temperature dependence of the dielectric constant and the relative dielectric constant is also large. Therefore, it has been difficult to stably control the temperature coefficient τf of the resonance frequency to be small while maintaining a high relative permittivity and a low dielectric loss.

Further, BaO-REO-TiO ₂ based materials include BaO—Nd ₂ O ₃ —TiO ₂
aO-Sm ₂ O ₃ but -TiO ₂ system and the like are known, in these systems is the relative dielectric constant εr very high as 60-100, also been obtained that the temperature coefficient τf of resonance frequency of 0 However, the Q value is as small as 5000 or less.

[0006] Further, in the case of MgTiO ₃ -CaTiO ₃ material, a Q value as large as 30000 and a temperature coefficient τf of the resonance frequency of 0 are obtained, but the relative dielectric constant is 16 to
25 and small.

As described above, none of the above-mentioned materials sufficiently satisfies the above three characteristics required for the high-frequency dielectric material.

Further, these materials can obtain a high Q value in a high-frequency region, but the Q value at a high temperature is much lower than the Q value at a room temperature. There was a problem that the no-load Q of the vessel became small.

Conventionally, Ln (rare earth element) -Al
-Ca-Ti dielectric porcelain composition is known, and even such a dielectric porcelain composition has a relative dielectric constant of 38.
~ 45, high Q value, temperature coefficient τf of resonance frequency
However, there is a problem that the retention of the Q value at a high temperature (120 ° C.) is insufficient. Further, with the development of the telecommunications industry, materials having higher Q values are required.

Accordingly, the present invention provides a high-frequency dielectric ceramic composition having a large relative dielectric constant, a high Q value, a small temperature dependency of a resonance frequency, and a high retention of the Q value at a high temperature with respect to room temperature. The purpose is to provide things.

[0011]

Means for Solving the Problems The present inventor has studied the above problems, and as a result, it has been found that the present invention comprises a composite oxide containing at least La, Al, Sr and Ti as metal elements. By controlling the molar ratio of the oxide and containing a specific amount of Mn, the relative dielectric constant is large, the Q value is high, the temperature dependence of the resonance frequency is small, and the Q value at a high temperature with respect to the Q value at room temperature is maintained. It has been found that a high frequency dielectric ceramic composition for high frequency can be obtained.

That is, 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, and has a composition formula based on the molar ratio of the metal elements: aLa ₂ O When expressed as ₃ · bAl ₂ O ₃ · cSrO · dTiO ₂ , the a, b, c, and d are 0.1061 ≦ a ≦ 0.2162 0.1050 ≦ b ≦ 0.2086 0.3040 ≦ c ≦ 0 0.4185 0.2747 ≦ d ≦ 0.4373 0.75 ≦ b / a ≦ 1.25 0.75 ≦ d / c ≦ 1.25 (where a + b + c + d = 1) where 100 parts by weight of the main component composition is satisfied. In contrast, Mn contains 0.01 to 3.0 parts by weight in terms of MnO ₂ .

Here, the carbon content in the porcelain composition is desirably 0.02% by weight or less based on the total amount. The Qf value at 120 ° C. is desirably 75% or more of the Qf value at 25 ° C.

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

[0015]

According to the high frequency dielectric ceramic composition of the present invention,
As a main component composition, at least La as a metal element,
Al, Sr and Ti are contained, and the composition formula based on the molar ratio of these metal elements is aLa ₂ O ₃ .bAl ₂ O ₃ .cS
When expressed as rO · dTiO ₂ , by controlling a, b, c, and d to specific ranges, the relative dielectric constant is large, the Q value is high, and the temperature characteristics of the resonance frequency are good and stable. In particular, the present invention is characterized in that La and Sr are used in combination, whereby LaAlO ₃ and SrTiO ₃ are used.
The solid solution of No. ₃ can be formed, and the Qf value can be improved.

Further, by containing Mn in a predetermined amount ratio with respect to the main component composition, a stable Qf value is exhibited, and the Qf value at a high temperature (120 ° C.) with respect to the Qf value of 25 ° C.
The retention of the f-value can be increased, and the unloaded Q of the resonator can be increased.

Further, in the present invention, by keeping the carbon content in the porcelain composition at 0.02% by weight or less in the total amount, the retention of the Qf value at a high temperature (120 ° C.) with respect to the Qf value at 25 ° C. is improved. It can be further improved.

Further, when the Qf value at 120 ° C. is 75% or more of the Qf value at 25 ° C., the stability of the Q value with respect to temperature can be improved, so that the stability of the resonator can be further improved. it can.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The high frequency dielectric ceramic composition of the present invention contains a composite oxide containing at least La, Al, Sr and Ti as metal elements as a main component composition. When a 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 , the a, b, c, and d are 0.1061 ≦ a ≦ 0.2162 0.1050 ≦ b ≦ 0.2086 0.3040 ≦ c ≦ 0.4185 0.2747 ≦ d ≦ 0.4373 0.75 ≦ b / a ≦ 1.25 0.75 ≦ d / c ≦ 1 .25 (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 0.1061 ≦ a ≦ 0.2162 is that when 0.1061> a, the temperature coefficient τf of the resonance frequency becomes positive and the temperature coefficient τf of the resonance frequency becomes large.
Absolute value greatly exceeds 30, and a> 0.216
In the case of 2, τf becomes large negatively, and the absolute value of τf becomes 30.
And the relative dielectric constant εr also decreases. a is preferably in the range of 0.1211 ≦ a ≦ 0.1450 in terms of the temperature coefficient τf of the resonance frequency and the Qf value.

The reason why 0.1050 ≦ b ≦ 0.2086 is that when 0.1050> b, the temperature coefficient τf of the resonance frequency becomes positive, the absolute value of τf greatly exceeds 30, and Qf This is because the value also decreases, and b> 0.208
In the case of 6, τf becomes large negatively, and the absolute value of τf becomes 30.
It is because it exceeds. b is, in particular, 0.1211
The range of ≦ b ≦ 0.1623 is preferred.

Further, 0.3040 ≦ c ≦ 0.4185
The reason is that when 0.3040> c, the temperature coefficient τf of the resonance frequency becomes negative and the absolute value of τf becomes 30
It is because it exceeds. In the case of c> 0.4185, the temperature coefficient τf of the resonance frequency becomes positive,
This is because the Q value is lower than 30,000. c is particularly preferably in the range of 0.3377 ≦ c ≦ 0.3789.

The reason that 0.2747 ≦ d ≦ 0.4373 is that when 0.2747> d, the temperature coefficient τf of the resonance frequency becomes negative and the absolute value of τf exceeds 30. When d> 0.4373, the temperature coefficient τf of the resonance frequency becomes positive, and τf
Is more than 30, and the Q value is lower than 30,000. In particular, 0.3
The range of 377 ≦ d ≦ 0.3789 is preferable.

Further, 0.75 ≦ b / a ≦ 1.25 is satisfied when 0.75> b / a or b / a> 1.25.
This is because, in the case of (1), the Qf value drops significantly, and drops below 30,000. b / a is set at 0.
It is desirable that 85 ≦ b / a ≦ 1.15.

Further, the reason that 0.75 ≦ d / c ≦ 1.25 is satisfied is that when 0.75> d / c, the relative permittivity εr becomes small, and when d / c> 1.25, Is because the relative permittivity εr increases. d / c is desirably 0.85 ≦ d / c ≦ 1.15 from the viewpoint of the relative dielectric constant εr.

Further, the present invention provides the above-mentioned main component composition 10
Relative to 0 parts by weight, 0.01 to Mn in MnO ₂ in terms of
It is important to contain 3.0 parts by weight. That is, Mn
To stabilize the Qf value without changing the relative permittivity εr and the temperature coefficient τf of the resonance frequency, and further, to the high temperature (120 ° C.) with respect to the Qf value of 25 ° C.
The rate of decrease of the f value can be reduced.

Here, the content of Mn is set to 0.01 to 3.0 parts by weight in terms of MnO _{2 because, if} it exceeds 3.0 parts by weight, the Qf value becomes extremely small, and the temperature coefficient of the resonance frequency becomes large. This is because τf shifts to the positive side. On the other hand, when the content of Mn is less than 0.01 part by weight in terms of MnO ₂ , there is almost no effect of addition. The content of Mn is from the viewpoint of dielectric characteristics improve, 0.05 in MnO ₂ in terms of
It is desirably 2.0 parts by weight.

Furthermore, in the high frequency dielectric ceramic composition of the present invention, the high temperature (120 ° C.) Qf value with respect to the Qf value of 25 ° C.
From the viewpoint of reducing the rate of decrease of the f-value, it is desirable that the carbon content in the porcelain composition is 0.02% by weight or less, particularly 0.01% by weight or less based on the total amount.

This carbon is usually used in an ordinary process of producing porcelain, when an organic binder for molding is added.
About 04% by weight is contained. Therefore, according to the present invention,
It is desirable to subject the molded body containing the organic binder to a binder removal treatment in an oxidizing atmosphere such as the air at a temperature of 600 ° C. or more for 10 hours or more, particularly at a temperature of 800 ° C. or more for 15 hours or more.

According to the present invention, by controlling the amount of carbon within the above range, the Qf value at 120 ° C. is reduced to 25%.
75% or more of the Qf value at ° C.

The high frequency dielectric ceramic composition of the present invention is produced, for example, as follows. As a starting material,
Using each powder of high-purity lanthanum oxide, aluminum oxide, strontium carbonate, and titanium oxide, after weighing to the desired ratio described above, pure water was added, and the average particle size of the mixed raw material was 2.0 μm or less. The wet mixing and pulverization are carried out by a mill using zirconia balls or the like for 10 to 30 hours until the mixture is obtained.

After drying the mixture, 1000 to 1300
Calcination treatment is performed at a temperature of 2 to 10 hours. In the obtained calcined material, M
nO ₂ is added in the specific range described above and mixed and pulverized. Further, a predetermined amount, for example, about 5% by weight of an organic binder for molding is added, and the resulting powder is sized. The obtained powder is optionally molded by a desired molding means, for example, a die press, a cold isostatic press, an extrusion molding or the like. After forming into a shape, the binder is removed in an oxidizing atmosphere such as air at a temperature of 600 ° C. or more and a holding time of 10 hours or more.
By firing in the air at a temperature of 700 ° C. for 1 to 10 hours, a dielectric porcelain can be obtained.

In the dielectric ceramic composition of the present invention, L
As a starting material for a, Al, Sr, and Ti, a compound that can generate an oxide by a heat treatment in an oxidizing atmosphere, such as a carbonate, an acetate, a nitrate, or a hydroxide, in addition to the oxide, is used. Is also good.

In the present invention, Ca, Zr, Si, Ba, and the like may be mixed as inevitable impurities in the porcelain. Absent.

The above-mentioned dielectric ceramic composition of the present invention is most useful for a dielectric resonator. FIG. 1 shows a schematic diagram of a TE mode dielectric resonator as the dielectric resonator of the present invention. The resonator shown in FIG. 1 is formed by forming an input terminal 2 and an output terminal 3 on both sides of a metal case 1 and arranging a dielectric ceramic 4 having the above-described composition between these terminals 2 and 3. You. As described above, in the TE mode type dielectric resonator, the microwave is input from the input terminal 2, and the microwave is confined in the dielectric ceramic 4 by the reflection of the boundary between the dielectric ceramic 4 and the free space, and is specified. Resonance occurs at the frequency of

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

[0037]

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,
Zr until the average particle size of the mixed raw material becomes 2.0 μm or less.
The wet mixing and pulverization were performed for about 20 hours using a mill using O ₂ balls.

After the mixture is dried, it is calcined at 1200 ° C. for 2 hours, and after adding 5% by weight of a binder, the particles are sized. The obtained powder is formed into a disk at a pressure of about 1 ton / cm ^2. Then, in the atmosphere, the debuoying temperature is 800 ° C., and the holding time is 1
The binder was removed under the condition of 0 hour, and thereafter,
It baked in the air at the temperature of 00-1700 degreeC for 2 hours.

The obtained porcelain was polished, ultrasonically cleaned in acetone, dried at 150 ° C. for 1 hour, and then room temperature (25 ° C.).
C), the measurement frequency is 3.5 to 3.5 by the cylindrical resonator method.
The relative permittivity εr, Qf value, and temperature coefficient τf of the resonance frequency were measured at 4.5 GHz. The Qf value was converted to a Qf value at 1 GHz from a relationship that is generally established in a microwave dielectric × a measurement frequency f = constant.

The temperature coefficient τf of the resonance frequency is -40 to 8
It was measured in the range of 5 ° C. Further, regarding the Qf value, 1
The Qf value at 20 ° C. was also measured, and the ratio of the Qf value at 120 ° C. to the Qf value at room temperature (25 ° C.) was calculated as the retention of the Qf value. The carbon content was measured by an infrared absorption method using a tubular resistance furnace. Table 1 shows the results.

[0041]

[Table 1]

As is clear from Table 1, in the dielectric ceramic composition outside the range of the present invention, the relative dielectric constant or the Qf value was low, or the absolute value of τf exceeded 30.

On the other hand, the dielectric ceramic composition of the present invention has a relative dielectric constant of 30 or more and a Q value of 30,000 (1 GHz).
z), τf is within ± 30 (ppm / ° C.),
The Qf value at 120 ° C. has a retention of 75% or more of the Qf value at 25 ° C., indicating that excellent dielectric properties can be obtained.

Example 2 Next, Mn was prepared at various ratios as shown in Table 2 with respect to the main component compositions exactly the same as Samples Nos. 1, 10 and 13 in Table 1 above.
O ₂ powder was added. Thereafter, the relative permittivity εr, Qf value, temperature coefficient of resonance frequency τf, and retention rate of Qf value of the porcelain obtained in the same manner as in Example 1 were measured. Table 2 shows the results.
It describes in.

[0045]

[Table 2]

From Table 2, it can be seen that 0.01 to 3.0 parts by weight of Mn.
, The Qf value is higher and more stable than the sample No. 31 without Mn added, and the high temperature (120
It can be seen that the retention of the Q value at room temperature (25 ° C.) at room temperature (° C.) increases.

Example 3 Next, the binder removal temperature and time were changed as shown in Table 3 with respect to the compositions of Samples Nos. 1, 10 and 13 in Table 1 above, and were completely the same. A plurality of porcelains having different carbon contents were produced. And for the obtained porcelain,
The relative permittivity εr, the Qf value, the temperature coefficient τf of the resonance frequency, and the holding ratio of the Qf value were measured in the same manner as in Example 1, and the results are shown in Table 3.

[0048]

[Table 3]

As is clear from the results in Table 3, when the carbon content in the porcelain is 0.02% by weight or less,
Q compared to the case where the amount of carbon is more than 0.02% by weight
It can be seen that the value is high and stable, and the retention of the Q value at room temperature (25 ° C.) at a high temperature (120 ° C.) is further increased.

[0050]

As described in detail above, according to the present invention, by adding Mn to a composite oxide containing at least La, Al, Sr and Ti in a specific ratio, a high dielectric constant in a high frequency region is obtained. Rate and a high Qf value, the temperature coefficient τf of the resonance frequency can be stably controlled to be small, and the high Q value is stabilized.
The retention of the Q value at a high temperature (120 ° C.) with respect to a room temperature (25 ° C.) can be kept high.

Thus, the dielectric ceramic composition for high frequency wave of the present invention can be used for, for example, automobile telephones, cordless telephones,
In devices such as personal radios and satellite broadcast receivers,
It is applied to resonator materials and MIC dielectric substrate materials, dielectric waveguides, dielectric antennas and other various electronic components used in microwave and millimeter wave regions.
It is suitable for dielectric resonators.

[Brief description of the drawings]

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

[Explanation of symbols]

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

Claims (4)

[Claims] 1. At least La, Al, S as a metal element
When composed of a composite oxide containing r and Ti, and a composition formula based on the molar ratio of the metal element is expressed as aLa ₂ O ₃ .bAl ₂ O ₃ .cSrO.dTiO ₂ , the a, b, c, and d are 0.1061 ≦ a ≦ 0.2162 0.1050 ≦ b ≦ 0.2086 0.3040 ≦ c ≦ 0.4185 0.2747 ≦ d ≦ 0.4373 0.75 ≦ b / a ≦ 1.25 0.75 ≦ d / c ≦ 1.25 (where, a + b + c + d = 1) 100 to 100 parts by weight of the main component composition satisfying the following condition: 0.01 to 3.0 parts by weight of Mn in terms of MnO _2. High frequency dielectric ceramic composition. 2. The high frequency dielectric ceramic composition according to claim 1, wherein the carbon content is 0.02% by weight or less based on the total amount. 3. The Qf value at 120 ° C. is at least 75% of the Qf value at 25 ° C.
Or the dielectric ceramic composition for high frequencies according to 2. 4. A dielectric resonator having a dielectric porcelain disposed between a pair of input / output terminals and operated by electromagnetic field coupling, wherein the dielectric porcelain is any one of claims 1 to 3. A dielectric resonator comprising the dielectric ceramic composition for high frequencies described above.