JP2001151568A - Dielectric porcelain composition for high frequency and dielectric resonator using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition useful for high frequency, which has a high Q value, is small in the decreasing rate of the Q value at 125 deg.C to that at 25 deg.C and exhibits small bending of temperature coefficient τf of the resonance frequency. SOLUTION: The dielectric porcelain composition contains, as metal elements, at least Mg, Ca and Ti, and at least one of Pr, Nd, Sm, La and Nb in an amount of 0.01 to 3 parts by weight expressed in terms of Pr6O11, Nd2O3, Sm2O3, La2O3 and Nb2O5, with proviso that when Nb is contained, the No amount is >=0.01 and <1 parts by weight in terms of Nb2O5, per 100 parts by weight of the main components wherein when the compositional formula, by molar ratio, of the metal elements of Mg, Ca and Ti is expressed by aMgO.bCaO.cTiO2, a, b and c satisfy following values: 0.42<=a<=0.51, 0.01<=b<=0.06, and 0.45<=c<=0.53, with proviso that a+b+c=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 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 materials that can be used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, multilayer ceramic capacitors, and impedance matching of various microwave circuits used in high-frequency regions such as waves The present invention relates to a body porcelain composition and a dielectric resonator.

[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. 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, Japanese Patent Application Laid-Open No. 7-282627 discloses CaO.
_{MgO · TiO 2 · La 2 O} 3 · CeO 2 material is shown,
The La ₂ O ₃ in a molar ratio of 0.07 <be La ₂ O ₃ <0.20 is contained is described. Also, Japanese Patent Application Laid-Open No. 7-262
824 JP _{CaO · MgO · TiO 2 · Nd} 2 O 3 ·
A CeO ₂ -based material is shown, wherein Nd ₂ O ₃ is contained in a molar ratio of 0.07.
It describes that <Nd ₂ O ₃ <0.20 is contained.

[0003]

However, these prior art dielectric ceramics have a curved temperature coefficient τf of the resonance frequency, that is, the linearity of the temperature drift is low. Further, the Q value at a high temperature (for example, 125 ° C.) is significantly lower than the Q value at a normal temperature (for example, 25 ° C.). For this reason, it is difficult for a dielectric resonator or a dielectric substrate using these dielectric porcelains to accurately control a characteristic change due to a temperature change, and the loss at a high frequency becomes large. Was. The present invention has been completed in view of the above circumstances.
While maintaining a high Q value at about 6 to 24, the high frequency dielectric has a bend in the temperature coefficient τf of the resonance frequency, that is, the linearity of the temperature drift is high, and the rate of decrease of the Q value at a high temperature with respect to the Q value at room temperature is small. An object is to provide a body porcelain composition and a dielectric resonator.

[0004]

The high frequency dielectric ceramic composition of the present invention comprises at least Mg, Ca,
Made from a composite oxide containing Ti, when the composition formula by molar ratio of the metal element expressed as aMgO · bCaO · cTiO _2, wherein a, b and c is, 0.42 ≦ a ≦ 0.51 0. 01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53 provided that the main component composition 100 satisfying a + b + c = 1
At least one of Pr, Nd, Sm, La and Nb is at least one of Pr ₆ O ₁₁ , Nd ₂ O ₃ and Sm _{2 based on} parts by weight.
O ₃ , La ₂ O _3, and Nb ₂ O ₅ as a total of 0.01 to 3
Parts by weight, and when Nb is contained, is 0.0% in terms of Nb ₂ O _5.
It is characterized by containing not less than 1 part by weight and less than 1 part by weight.

[0005] Further, in the above dielectric ceramic composition,
Q value at 125 ° C. is 75% of Q value at 25 ° C.
The above is the feature.

Further, in the dielectric resonator according to the present invention, a dielectric porcelain is arranged between a pair of input / output terminals, wherein the dielectric porcelain operates by electromagnetic field coupling. It is composed of a body porcelain composition.

According to the high frequency dielectric ceramic composition of the present invention,
By including at least one of Pr, Nd, Sm, La, and Nb in the main component, the material has a high Q value and a bend (temperature drift) of the temperature coefficient τf of the resonance frequency at 25 to 85 ° C. Control within the range of 0 ± 3 (ppm / ° C.), that is, it is possible to increase the linearity of the temperature drift. In addition, it is possible to reduce the rate of decrease in the Q value at a high temperature with respect to the Q value at a normal temperature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a metal element
Complex oxide containing at least Mg, Ca, Ti
And the composition formula based on the molar ratio of the metal element is aMgO
・ BCaO ・ cTiO_TwoWhere a, b and
And c is 0.42 ≦ a ≦ 0.51 0.01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53 where a + b + c = 1 is satisfied.
Parts by weight of Pr, Nd, Sm, La and Nb
At least one of them is Pr₆O₁₁, Nd_TwoO_Three, Sm_Two
O_Three, La_TwoO_ThreeAnd Nb_TwoO_Five0.01-3 in total
Parts by weight and Nb when Nb _TwoO_FiveIn conversion
It is important to contain 0.01 to less than 1 part by weight.
is there. These a, b, c, and Pr₆O₁₁, Nd
_TwoO_Three, Sm_TwoO_Three, La_TwoO_ThreeAnd Nb_TwoO_FiveThe content of
The reason for limiting to the above range is as follows.

That is, 0.42 ≦ a ≦ 0.51 means that when 0.51 <a, the Q value decreases or τf becomes negative and the absolute value of τf exceeds 50. Because. When a <0.42, the Q value decreases, τf increases positively, the absolute value of τf greatly exceeds 50, the temperature coefficient τf of the resonance frequency bends greatly, and the linearity of the temperature drift decreases. It is because it is lowered. In particular, 0.43 <a <0.49 is desirable.

The reason for setting 0.01 ≦ b ≦ 0.06 is that when 0.06 <b, the temperature coefficient τf of the resonance frequency becomes positive, the absolute value of τf greatly exceeds 50, and Q
When b <0.01, τf becomes negative, the absolute value of τf exceeds 50, and the bending of the temperature coefficient τf of the resonance frequency increases, and the linearity of the temperature drift decreases. Because they do. In particular, 0.02
≦ b ≦ 0.05 is preferred.

Further, the reason that 0.45 ≦ c ≦ 0.53 is satisfied is that when 0.53 <c, the temperature coefficient τ
This is because f becomes positive and the absolute value of τf greatly exceeds 50, and the bending of the temperature coefficient τf of the resonance frequency increases, and the linearity of the temperature drift decreases. c <
This is because in the case of 0.45, the Q value decreases and the relative dielectric constant decreases. In particular, the range of 0.46 ≦ c ≦ 51 is preferable.

Also, Pr, Nd, Sm, La and Nb
At least one of Pr ₆ O ₁₁ , Nd ₂ O ₃ , S
m ₂ O ₃ , La ₂ O _3, and Nb ₂ O ₅ as a total of 0.01 to
The reason for containing 3 parts by weight is that when the amount is less than 0.01 part by weight, the linearity of the temperature drift is low, and when the amount is more than 3 parts by weight, the reduction rate of the Q value at a high temperature (125 ° C.) is large. is there. When Nb is contained, it is 0.01 in Nb ₂ O ₅ conversion.
More than 1 part by weight and less than 1 part by weight is because when less than 0.01 part by weight, the linearity of the temperature drift is low,
This is because when the amount is 1 part by weight or more, the reduction rate of the Q value at a high temperature (125 ° C.) is large. In particular, Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂
O ₃ , La ₂ O _3, and Nb ₂ O ₅ as a total of 0.05 to-
It is desirable to contain 2.5 parts by weight. When containing Nb it is desirably contains 0.05 to 0.8 parts by weight calculated as Nb ₂ O _5.

[0012] In the present invention, the Q value is a Q value generally established in a microwave dielectric x a measurement frequency f =
It shows a value converted to a Qf value at 1 GHz from a certain relationship.

Thus, the high frequency dielectric ceramic composition of the present invention has a high dielectric constant of about 16 to 24 and a high Q value,
High linearity of temperature drift and Q at room temperature (25 ° C)
75% retention of Q value at high temperature (125 ° C)
This has the operational effect of the above. The retention ratio of the Q value at high temperature (125 ° C) to the Q value at normal temperature (25 ° C) is 75
% Of the dielectric porcelain composition in the dielectric resonator, the output signal is hardly attenuated even if the temperature around the resonator changes. Thus, an excellent dielectric resonator can be obtained.

The high frequency dielectric ceramic composition of the present invention is produced, for example, as follows. As a starting material,
Using each powder of magnesium carbonate, calcium carbonate and titanium oxide, after weighing to the desired ratio described above, pure water is added, and the mixed raw material has an average particle size of 2.0 μm or less for 10 to 30 hours. And wet milling / pulverization with a mill using zirconia balls or the like.

After drying this mixture, 1000 to 1300
Calcination treatment is performed at a temperature of 2 to 10 hours. In the obtained calcined material, praseodymium oxide, neodymium oxide, samarium oxide,
Lanthanum oxide and niobium oxide are 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 then sizing is performed.
Desired molding means obtained powder, for example, a mold press,
After being formed into an arbitrary shape by cold isostatic pressing, extrusion molding or the like, 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. After that, 1300-1400 ° C
By sintering in the air at the above temperature for 1 to 10 hours, a dielectric porcelain can be obtained.

In the present invention, by using the above-described manufacturing method within a specific composition range, a bending (temperature drift) of the temperature coefficient τf of the resonance frequency is limited to 0 ± 25 ° C. at 25 to 85 ° C. 3 (ppm / ° C.), that is, the linearity of the temperature drift can be increased. In addition, it is possible to reduce the rate of decrease in the Q value at a high temperature with respect to the Q value at a normal temperature.

The starting material of the dielectric ceramic composition for a high frequency wave according to the present invention may be oxidized by heat treatment in an oxidizing atmosphere such as carbonate, acetate, nitrate, carbonate, hydroxide and the like in addition to oxide. A compound capable of producing a product may be used. Further, for Mg, Ca and Ti, MgTiO ₃ , Ca produced by a sol-gel method or a hydrothermal method, etc.
A TiO ₃ compound may be used.

In the present invention, Zr, Si, Ba and the like may be mixed as unavoidable impurities in the porcelain. However, if these are mixed in 0.4% by weight or less in terms of oxide, there is no problem in characteristics. .

The high frequency 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. 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 ceramic 4 having the above-described composition is provided between these terminals 2 and 3.
Are arranged. Thus, in the TE mode type dielectric resonator, the microwave is input from the input terminal 2,
The microwave is confined in the dielectric porcelain 4 by reflection at the boundary between the dielectric porcelain 4 and the free space, and causes resonance at a specific frequency.

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

[0021]

EXAMPLES Using high-purity magnesium carbonate (MgCO ₃ ), calcium carbonate (CaCO ₃ ), and titanium oxide (TiO ₂ ) powders as starting materials, they were listed in Table 1.
After weighing so that the molar ratio of the mixture becomes, pure water was added, and wet mixing and grinding were performed for about 20 hours by a mill using ZrO ₂ balls 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. To the obtained calcined product, high-purity praseodymium oxide (Pr ₆ O ₁₁ ), neodymium oxide (Nd ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), and lanthanum oxide (La ₂ O) were obtained as shown in Table 1. ₃ ), niobium oxide (Nb ₂ O ₅ )
Was added and wet-mixed and milled by a mill using ZrO ₂ balls for about 20 hours until the average particle size of the mixed raw material became 2.0 μm or less. After drying the slurry, 5 wt% of a binder was further added, and the resulting granules were sized. The obtained powder was formed into a disk at a pressure of about 1 ton / cm ² . The obtained molded body is removed in the air at a binder removal temperature of 800 ° C.
The binder was removed under the condition of a holding time of 10 hours, and then fired in the air at a temperature of 1300 to 1500 ° C. for 8 hours.

The obtained porcelain is polished flat, ultrasonically cleaned in acetone, dried at 150 ° C. for 1 hour, and then room temperature at 25 ° C.
At a measurement frequency of 8 to 10 GH by a cylindrical resonator method.
The relative dielectric constant εr and Q value were measured at z. Qf is a Q value generally established in a microwave dielectric × a measurement frequency f =
It was converted to a Qf value at 1 GHz from a certain relationship. Further, the Q value at a high temperature of 125 ° C. was measured in the same manner, and the retention of the Q value at 125 ° C. with respect to the Q value at 25 ° C. was calculated.

The temperature coefficient τf of the resonance frequency is 25 to 85
It was measured in the range of ° C. Τf at 25 to 55 ° C.
The value obtained by subtracting τf of 55 to 85 ° C from the above was defined as τf bending (temperature drift).

[0025]

[Table 1]

As is clear from Table 1, the dielectric ceramic composition outside the range of the present invention has a low relative dielectric constant, a low Q value, or an absolute value of τf exceeding 50. Or τf bend (temperature drift) is 0 ± 3pp
m / ° C.

In contrast, the dielectric ceramic composition of the present invention has a relative dielectric constant of 20 to 23 and a Q value of 80,000 (1 G
Hz), τf is within ± 50 (ppm / ° C.), and the bending (temperature drift) of τf is 0 ± 3 (ppm / ° C).
℃), the Q value of 125 ° C against the Q value of 25 ° C is 75
%, Which indicates that excellent dielectric properties can be obtained.

[0028]

As described in detail above, the composition is composed of a composite oxide containing at least Mg, Ca, and Ti as the metal elements, and the composition formula based on the molar ratio of the metal elements is aMgO.
When expressed as bCaO · cTiO ₂ , the a, b and c are 0.42 ≦ a ≦ 0.51, 0.01 ≦ b ≦ 0.
06, 0.45 ≦ c ≦ 0.53 (where a + b + c =
With respect to 100 parts by weight of the main component composition satisfying 1), P
At least one of r, Nd, Sm, La and Nb is contained in the above-mentioned specific range in terms of Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , La ₂ O ₃ and Nb ₂ O _5. By doing so, it has a high Q value, the decrease rate of the Q value at 125 ° C. with respect to 25 ° C. is small, and the bending (temperature drift) of the temperature coefficient τf of the resonance frequency is 0 ± 3 in the range of 25 to 85 ° C. (Ppm / ° C.).

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

[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 (3)

[Claims] (1) at least Mg, Ca, T as a metal element;
a composite oxide containing i
The composition formula based on the ratio is expressed as aMgO.bCaO.cTiO._TwoAnd table
Then, a, b, and c are as follows: 0.42 ≦ a ≦ 0.51 0.01 ≦ b ≦ 0.06 0.45 ≦ c ≦ 0.53 where a + b + c = 1 100
Parts by weight of Pr, Nd, Sm, La and Nb
At least one of them is Pr₆O₁₁, Nd_TwoO_Three, Sm_Two
O_Three, La_TwoO_ThreeAnd Nb_TwoO_Five0.01-3 in total
Parts by weight and Nb when Nb _TwoO_FiveIn conversion
Characterized in that it contains not less than 0.01 part by weight and less than 1 part by weight.
High frequency dielectric ceramic composition. 2. The high frequency dielectric ceramic composition according to claim 1, wherein the Q value at 125 ° C. is 75% or more of the Q value at 25 ° C. 3. A high frequency dielectric ceramic composition according to claim 1 is disposed between a pair of input / output terminals to operate by electromagnetic field coupling. Dielectric resonator.