JP2003300773A - Dielectric composition and dielectric ceramic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To independently control the ε<SB>r</SB>(relative dielectric constant) and τ<SB>f</SB>(temperature coefficient of resonance frequency) in a dielectric composition and a dielectric ceramic. <P>SOLUTION: The dielectric composition containing Ba, Nb, Sn, Ta, Zn and Co and M (wherein, M is at least one or more kinds of metals selected from K, Na and Li) is produced and the ε<SB>r</SB>and τ<SB>f</SB>of the produced dielectric composition and dielectric ceramic can independently be controlled while highly retaining the product of the nonload quality coefficient Q<SB>u</SB>and resonance frequency f<SB>0</SB>, i.e., f<SB>0</SB>Q<SB>u</SB>of the dielectric composition and dielectric ceramic. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel dielectric composition and dielectric porcelain which are applied to high frequency regions such as microwaves and millimeter waves. A dielectric ceramic is a bulk made of a dielectric composition, and examples thereof include electronic parts such as a dielectric resonator, a dielectric substrate, a dielectric filter and a dielectric antenna.

[0002]

2. Description of the Related Art Conventionally, it is said that the relative dielectric constant (hereinafter referred to as “ε _r ”) is large, the dielectric loss is small, and the absolute value of the temperature coefficient of resonance frequency (hereinafter referred to as “τ _f ”) is small. Various dielectric compositions for use in a high frequency region such as microwaves and millimeter waves that require dielectric properties have been investigated.

Among them, the Ba (Zn, Co) NbO ₃ -based dielectric composition has a product of a no-load quality factor (hereinafter referred to as “Q _u ”) and a resonance frequency (hereinafter referred to as “f ₀ ”). (Hereinafter referred to as “f ₀ · Q _u ”) is high and the absolute value of τ _f is small, which is an excellent dielectric property. For example, Japanese Patent Publication Nos. 2-53884 and 4-321 disclose dielectric compositions containing the Ba (Zn, Co) NbO ₃ -based component.

In addition, the inventors of the present invention have so far used Ba (Zn, C
o) Addition of KTaO ₃ to the NbO ₃ -based dielectric composition to increase f ₀ · Q _u and increase the substitution amount of Co for Zn, thereby making ε _r and τ _f small and tunable dielectric. I have studied body composition.

However, when the above dielectric composition is applied to a dielectric ceramic (for example, a dielectric resonator), it is difficult to control ε _r and τ _f independently. For this reason,
The dielectric composition applied to the dielectric porcelain has been complicated because it must be newly examined for each application.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dielectric composition and a dielectric porcelain capable of independently controlling ε _r and τ _f while maintaining a high f ₀ · Q _u. And to provide a dielectric resonator.

[0007]

(1) In order to achieve the above object, a dielectric ceramic composition according to claim 1 of the present invention comprises Ba, Nb, Sn, Ta, Zn, Co, and M. (However, M is at least one or more of K, Na and Li), wherein when each component element in the dielectric composition is converted into an oxide, The molar ratio (%) of each oxide is 49.7 ≦ BaO ≦ 68.6 8.11 ≦ Nb ₂ O ₅ ≦ 23.1 0.134 ≦ Ta ₂ O ₅ ≦ 10.0 0 <ZnO <24. 90 <CoO <24.9 0.0837 ≦ M ₂ O ≦ 20.9 (where M is K, N
a, which is either one of Li and Li), and whose total molar ratio (%) of the oxides is 100.
When Sn is converted to SnO ₂ with respect to the molar part, 0 <S
The gist is a dielectric composition characterized by containing a molar ratio (%) of nO ₂ ≦ 33.3.

The dielectric composition of the present invention has a high f ₀ · Q _u , and by changing both the Sn content and the substitution amount of Co for Zn, ε _r of the dielectric composition is changed.
And τ _f can be controlled independently. That is,
It becomes possible to obtain dielectric compositions having the same ε _r but different τ _f . Similarly, it becomes possible to obtain a dielectric composition having the same τ _f but different ε _r .

C to Zn in the dielectric composition of the present invention
By increasing the substitution amount of o, it becomes possible to control the values of ε _r and τ _f to be small. Further, by decreasing the substitution amount of Co for Zn, the values of ε _r and τ _f are increased,
Be able to control.

By increasing the content of Sn in the dielectric composition of the present invention, it becomes possible to control the values of ε _r and τ _f to be small. In addition, the Sn
It becomes possible to control the values of ε _r and τ _f to be large by decreasing the content of _{γ r} .

M and Ta constitute MTaO ₃ in the dielectric composition of the present invention. MTaO ₃ increases the f ₀ · Q _u of the dielectric composition of the present invention.

The molar ratio (%) of BaO is 49.7 ≦ BaO.
The reason why ≦ 68.6 is as follows. When the molar ratio (%) of BaO is less than 49.7, τ _f is large, f ₀ · Q _u cannot be sufficiently high, or the shape of the molded body cannot be maintained during firing. , It may not be applicable to the product and is not preferable. On the other hand, when the molar ratio (%) of BaO exceeds 68.6, τ _f may be small, or f ₀ · Q _u may not be sufficiently large,
It may be difficult for the dielectric composition to be sufficiently sintered, which is not preferable.

The molar ratio (%) of Nb ₂ O ₅ is 8.11 ≦ N
The reason for b ₂ O ₅ ≦ 23.1 is as follows.
When the molar ratio (%) of Nb ₂ O ₅ is less than 8.11.
There is a case where ₀ · Q _u does not have a sufficiently large value or τ _f becomes small, which is not preferable. On the other hand, Nb ₂ O
_When the molar ratio (%) of ₅ exceeds 23.1, τ _f may increase, which is not preferable.

Ta_TwoO₅Has a molar ratio (%) of 0.134 ≦
Ta_TwoO₅The reason for ≦ 10.0 is as follows.
It Ta_TwoO₅Has a molar ratio (%) of less than 0.134
And f ₀・ Q_uMay not be large enough.
It is not preferable. On the other hand, Ta _TwoO₅The molar ratio of
If it exceeds 10.0, τ_fWhen it becomes large or when firing
In some cases, the shape of the molded product cannot be maintained and cannot be applied to products.
Yes, it is not preferable.

The molar ratio (%) of ZnO is 0 <ZnO <2.
The reason for becoming 4.9 is as follows. If ZnO is not contained, a sufficiently large value of f ₀ · Q _u may not be obtained or τ _f may be low, which is not preferable. On the other hand, when the molar ratio (%) of ZnO is 24.9 or more, τ
_{Since f} may become large, it is not preferable.

The molar ratio (%) of CoO is 0 <CoO <2.
The reason for becoming 4.9 is as follows. If CoO is not contained, τ _f may increase, which is not preferable. On the other hand, when the molar ratio (%) of CoO is 24.9 or more, a sufficiently large f ₀ · Q _u cannot be obtained, or τ _f
May become small, which is not preferable.

The molar ratio (%) of M ₂ O is 0.0837 ≦
The reason for M ₂ O ≦ 20.9 is as follows. M ₂
If the molar ratio (%) of O is less than 0.0837, a sufficiently large f ₀ · Q _u may not be obtained, or it may be difficult to sufficiently sinter the dielectric composition. Not preferable. On the other hand, when the molar ratio (%) of M ₂ O exceeds 20.9, a sufficiently large f ₀ · Q _u cannot be obtained, or τ _f
May become large, which is not preferable.

BaO, Nb_TwoO₅, Ta_TwoO₅, Zn
O, CoO and M_Two100 parts by mole of O
To SnO_TwoHas a molar ratio of 0 <SnO_Two<33.3 and
The reason is as follows. SnO_TwoIs included
If there is no τ_fMay increase, which is not preferable. one
One, SnO_TwoWhen the molar ratio of f exceeds 33.3, f₀・ Q
_uIs not sufficiently large, or τ_fIs small
In some cases, it is not preferable.

(2) To achieve the above object, the dielectric ceramic composition according to claim 2 of the present invention is characterized in that M is K, and the dielectric composition according to claim 1. The main point is the thing. A dielectric composition in which M is K is M is L
It has a larger f ₀ · Q _u than the dielectric composition of i and Na, and the sinterability of the dielectric composition is more preferable.

(3) In order to achieve the above object, the dielectric ceramic according to claim 3 of the present invention is characterized by comprising the dielectric composition according to claim 1 or 2. The main point is body porcelain. The dielectric porcelain is f ₀ ·
Ε _r and τ _f can be controlled independently while maintaining a high Q _u value

(4) A dielectric resonator according to claim 4 of the present invention for achieving the above object is characterized by comprising the dielectric composition according to claim 1 or 2. The main point is a dielectric resonator. The dielectric resonator can control ε _r and τ _f independently while maintaining a high f ₀ · Q _u value.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION A dielectric composition according to the present invention and
An example of a preferable aspect of the dielectric porcelain will be described below.
To do. <Example> [1] Preparation of dielectric composition Commercially available barium carbonate having the composition ratio shown in Table 1.
(BaCO_Three) Powder, zinc oxide (ZnO_Two) Powder, oxidation
Cobalt (CoO) powder, niobium oxide (Nb_TwoO ₅)powder
Powder, tantalum oxide (Ta_TwoO₅) Powder, alkali metal charcoal
Acid salt (M_TwoCO_Three) Powder and tin oxide (SnO)_Two)powder
Powder (All powders must have a purity of 99.9% or more.
Each) for 20 to 30 minutes with a mixer
After dry-mixing for a while, primary pulverization was performed with a vibration mill. Na
Nylon balls are used for the cobblestones, and the crushing time is 3:00
It was between.

[0023]

[Table 1]

By mixing, the obtained powder was calcined in the atmosphere at 1100 to 1300 ° C. for 2 hours to obtain a calcined powder. An appropriate amount of organic binder and water were added to the calcined powder, and the mixture was mixed for 2 to 10 hours with a trommel crusher.
Next, crushing was performed. Then, after freeze-drying and granulating,
A granulated powder having a particle size of 40 to 200 mesh is selected by a sieve, and the granulated powder has a diameter of 19 m by a press machine.
m and height 11 mm. After that, the obtained molded body was degreased at 500 ° C. for 4 hours, and held in the atmosphere at the temperature shown in Table 2 for 3 hours to be fired.
.About.27 and Comparative Examples 1 to 21 were obtained as bulk dielectric compositions.

[0025]

[Table 2]

[2] Identification of Crystal Phase The dielectric composition obtained in [1] was crushed in a mortar,
It was made into a powder, and X-ray diffraction measurement was performed using CuKα rays. The results are shown in Fig. 1.

[3] Evaluation of Dielectric Properties The dielectric composition obtained in [1] was used in a diameter of 16 mm,
The sample piece was polished into a cylindrical shape having a height of 8 mm. Then, the polished sample piece was subjected to ε _r , f ₀ · Q _u , τ _f (temperature range: 25 to 25 by the TE ₀₁₁ mode at a measurement frequency of 4.5 GHz using a parallel conductor plate type dielectric resonator method.
80 ° C.) was measured. The results are also shown in Table 1. Further, the specimen using a dielectric resonator method at a measuring frequency 3.5 GHz, the _{TE 01Deruta} mode _{Q u} and f
₀ was measured, and the result is also shown in Table 2 as f ₀ · Q _u .

[4] Manufacture of Dielectric Resonator A dielectric resonator having the same components as the dielectric composition obtained in Example 8 was manufactured. The dielectric resonator is shown in FIG. In the process of producing the dielectric composition of Example 8, a resonator body was prepared in a molding process, the resonator was housed in a cylindrical metal cavity, and the support base side was faced down. It is placed on the bottom surface in the center, and the through hole provided in this center is used to fix the resonator body and the cylindrical metal container together with bolts and nuts to fabricate a dielectric resonator. did. The dimensions of each part in FIG. 6 are D 80 mmφ, L 70 mm, and d ₁ 38 mm.
φ, d ₂ is 32 mm φ, l ₁ is 17 mm, l ₂ is 20 m
m. Using the dielectric composition obtained in Comparative Example 19, the resonator shown in FIG. 6 was prepared in the same manner as in Example 8.

(1) Crystal Phase of Dielectric Composition FIG. 1 shows an X-ray diffraction measurement chart of the dielectric composition of Example 8 as an example of the dielectric composition of the present invention. The observed peaks are 2θ = 31.02, 3
8.20, 44.35, 55.01, 64.40, 7
There is 3.06.

The peaks indicated by ● in the X-ray diffraction chart are shifted to the wide-angle side with respect to the peak of BaZn _1/3 Nb _2/3 O ₃ . This is the dielectric composition BaZn
Part of Zn in _1/3 Nb _2/3 O ₃ is replaced with Co,
Solid solution Ba (Zn _1-x Co _x ) _1/3 Nb _2/3 O ₃
To form Zn, Co and Nb in the solid solution.
Suggests that a part of is replaced by Sn.

(2) Effect of Zn and Co Regarding Zn and Co contained in the dielectric composition of the present invention,
Converted to ZnO and CoO respectively, ZnO and Co
FIG. 2 shows changes in ε _r and FIG. 3 shows changes in τ _f with respect to the ratio of the molar ratio of CoO in the total molar ratio of O (Example 12, Example 14, Example 18).

In FIG. 2, by increasing the substitution amount of Co for Zn (molar ratio (%) of CoO) from 45.1% (Example 12) to 84.6% (Example 18), ε _r decreases from 30.5 (Example 12) to 27.7 (Example 18). From this, it is understood that the dielectric composition of the present invention can control ε _r by increasing or decreasing the substitution amount of Co with respect to Zn (the ratio of the molar ratio of CoO (%)).

In FIG. 3, by increasing the substitution amount of Co for Zn (ratio of molar ratio (%) of CoO) from 45.1% (Example 12) to 84.6% (Example 18), τ _f is 7.9 ppm / ° C. (Example 12) to −1
Reduced to 3.2 ppm / ° C (Example 18). From this, it is understood that the dielectric composition of the present invention can control τ _f by increasing or decreasing the substitution amount of Co with respect to Zn (the ratio of the molar ratio of CoO (%)).

(3) Effect of Sn Sn contained in the dielectric composition of the present invention is SnO._TwoConverted to
When doing, SnO_TwoΕ for changes in the molar ratio of
_r4 (Example 5, Example 9, Example 12,
Example 15, Example 17, Example 20, Example 22, Example
In Example 23), τ _f5 (Example 5, Example 9,
Example 12, Example 15, Example 17, Example 20, Example
Example 22 and Example 23) are shown.

In FIG. 4, the content of Sn (molar ratio of SnO ₂ ) contained in the dielectric composition was 2.90 mol%.
By increasing (Example 5) to 33.0 mol% (Example 23), ε _r was changed from 35.0 (Example 5) to 2
It decreased to 2.4 (Example 23). From this fact, the dielectric composition of the present invention is not limited to Sn contained in the dielectric composition.
It can be seen that ε _r can be controlled by increasing or decreasing the content of (the molar ratio of SnO ₂ ).

In FIG. 5, the content of Sn (molar ratio of SnO ₂ ) contained in the dielectric composition was 2.90 mol%.
By increasing (Example 5) to 33.0 mol% (Example 23), τ _f was decreased from 13.5 ppm / ° C (Example 5) to -14.7 ppm / ° C (Example 23). There is. From this, the content of Sn contained in the dielectric composition of the present invention (molar ratio of SnO ₂ )
It can be seen that τ _f can be controlled by increasing or decreasing.

(4) ε_rAnd τ_fControl of In the examples of the present invention shown in Table 3, the results of Example 14 and
Example 15 has the same ε _r29.7 to Example 18
And the two sets of dielectric compositions of Example 19 have the same ε_rAnd
27.7, each dielectric composition
Different τ_fhave. In the present invention, the same
One τ_fBut different ε_rDielectric set having
You can also get the product. from these things,
In the dielectric composition of the present invention, the substitution amount of Co with respect to Zn and
By increasing and decreasing the molar ratio of Sn and Sn, ε_rAnd τ
_fIt can be seen that can be controlled independently.

[0038]

[Table 3]

(5) Element of M In Table 4, M was set to K, Li and Na, and the electrical characteristics of Example 15, Example 24 and Example 26 having the same M content were compared. Although M can obtain good electric characteristics in any of K, Li, and Na, the dielectric composition in which M is K is f ₀ · Q _u compared to the dielectric composition in which M is Li or Na.
Is higher. From this, the dielectric composition of the present invention is
It can be seen that when the molar ratio of the other component elements is the same, the dielectric composition containing K has a higher Q value and a better dielectric composition can be obtained.

[0040]

[Table 4]

(6) Characteristics of dielectric resonator In [4], T of the manufactured dielectric resonator of Example 8 was used.
E_01δResonance frequency in mode is 1800MHz
So that Q_uWas measured. Got Q _uIs 32
It was 470. Comparative Example 19 produced in [4]
TE of dielectric resonator_01δResonance frequency in mode
Is set to 1910MHz, and Q_uWas measured.
Got Q_uWas 3752. Dielectric resonance of the present invention
The container is Q_uIs kept high and ε_rAnd τ_fControl independently
can do.

Although the preferred embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to this embodiment and can be appropriately modified without departing from the spirit of the present invention.

[0043]

As described above, in the dielectric composition of the present invention, ε _r and τ _f can be controlled independently. INDUSTRIAL APPLICABILITY The dielectric composition of the present invention can be applied to a dielectric resonator or the like having wide electrical characteristics suitable for various uses.

[Brief description of drawings]

FIG. 1 is an X of a dielectric composition according to an embodiment of the present invention.
It is a line diffraction chart.

FIG. 2 shows Zn and Co contained in the dielectric composition of the present invention when converted to ZnO and CoO, respectively.
6 is a graph showing changes in ε _r with respect to the ratio of the molar ratio of CoO in the total molar ratio of O and CoO.

FIG. 3 shows Zn and Co contained in the dielectric composition of the present invention when converted to ZnO and CoO, respectively.
It is a graph which shows change of (tau) _f with respect to the ratio of the molar ratio of CoO in the total of the molar ratio of O and CoO.

Respect Sn contained in the dielectric composition of the present invention; FIG, when converted to SnO _2, with respect to a molar ratio of SnO _2, is a graph showing changes in epsilon _r.

Respect Sn contained in the dielectric composition of the present invention; FIG, when converted to SnO _2, with respect to a molar ratio of SnO _2, is a graph showing changes in tau _f.

FIG. 6 is a diagram showing one mode of a dielectric resonator of the present invention.

[Explanation of symbols]

1 resonator 1a support 2 metal cavities 3 bolts

Continued front page    (72) Inventor Kazuhisa Itakura             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. F-term (reference) 4G030 AA02 AA03 AA04 AA10 AA20                       AA21 AA28 AA32 AA39 BA09                 5G303 AA02 AA05 AB06 AB07 AB20                       CA01 CB03 CB09 CB14 CB16                       CB20 CB21 CB33 CB38                 5J006 HC04 HC07 HC21 HC25

Claims (4)

[Claims] 1. Ba, Nb, Sn, Ta, Zn, Co,
A dielectric composition containing M (provided that M is at least one or more of K, Na and Li), and each component element in the dielectric composition is converted into an oxide, The molar ratio (%) of each of the oxides is 49.7 ≦ BaO ≦ 68.6 8.11 ≦ Nb ₂ O ₅ ≦ 23.1 0.134 ≦ Ta ₂ O ₅ ≦ 10.0 0 <ZnO <24 0.90 <CoO <24.9 0.0837 ≦ M ₂ O ≦ 20.9 (where M is K, N
a, which is either one of Li and Li), and whose total molar ratio (%) of the oxides is 100.
When Sn is converted to SnO ₂ with respect to the molar part, 0 <S
A dielectric composition containing nO ₂ ≦ 33.3 in a molar ratio (%). 2. The dielectric composition according to claim 1, wherein M is K. 3. A dielectric porcelain comprising the dielectric composition according to claim 1 or 2. 4. A dielectric resonator comprising the dielectric composition according to claim 1 or 2.