JP3243890B2 - Dielectric porcelain composition - Google Patents

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 suitable as a material for a dielectric resonator or the like. The dielectric ceramic composition of the present invention can be applied to, for example, a dielectric substrate for microwave IC, a dielectric adjustment rod, and the like, in addition to the dielectric resonator material.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a small and high-performance dielectric resonator has been demanded. Such dielectric ceramic compositions used in the dielectric resonator, the specific dielectric constant epsilon _r is large, it unloaded Q is large, also the stability is good like temperature coefficient tau _f of the resonant frequency Characteristics are required.

Heretofore, BaO-TiO ₂ based dielectric ceramic compositions have been known as dielectric resonators having excellent characteristics. For example, in Japanese Patent Application Laid-Open Nos. 56-102003 and 57-21010, BaO-TiO
_{2 -Nd 2 O 3 -Bi 2 O} 3 system, BaO-TiO ₂ -S
m ₂ O ₃ -Nd ₂ O ₃ based ceramic compositions have been proposed.
However, the characteristics are still insufficient, and there is room for improvement in the reproducibility of the electrical characteristics.

In the case where the material is used in various fields as a material for a dielectric resonator or the like, the temperature coefficient τ of the resonance frequency
_f is a problem, and there is a need for a dielectric ceramic composition having a large relative dielectric constant ε _r and a large unloaded Q, and further having an excellent temperature coefficient τ _f . In particular, since the temperature coefficient τ _f of the resonance frequency in the Ba—Ti system is +4 to +10 ppm / ° C. and is large on the positive side, the dielectric ceramic composition in which the temperature coefficient τ _f is controlled and shifted to the negative side is used. It has been demanded. In order to realize this, it has been attempted to add another element to the BaO-TiO ₂ system or to substitute it with another element. However, the relative dielectric constant is small, and the unloaded Q is still small. Was not enough.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dielectric ceramic composition having more excellent properties as a dielectric resonator material, especially a high dielectric constant, a large unloaded Q, and a temperature coefficient τ of the resonance frequency.
_An object of the present invention is to provide a dielectric ceramic composition having good stability of _f and capable of controlling τ _f from a negative side to a positive side.

[0006]

According to the present invention, there is provided a composition formula, x
BaO-y [(1-z) TiO ₂ .zZrO ₂ ] (wherein,
0.1818 ≦ x ≦ 0.2, 0.8 ≦ y ≦ 0.818
2, 0 <z ≦ 0.1, and x + y = 1. ), And controls the temperature coefficient τ _f of the resonance frequency from the negative side to the positive side.
The present invention relates to a dielectric ceramic composition comprising barium, titanium, zirconium and oxygen.

[0007] The present invention relates to a method for preparing a specific amount of BaO, TiO._TwoThe lord
TiO2_TwoPart of ZrO _TwoReplace a specific amount with
This improves the difficulties of conventional dielectric porcelain compositions.
It is based on the finding that

In the present invention, the molar fraction x of BaO is greater than 0.2, or the molar fraction x of BaO is O.O. 1
If it is smaller than 818, the temperature coefficient τ _f of the resonance frequency increases, so that the molar fraction x of BaO and TiO ₂ and Zr
The total molar fraction y with O ₂ is set in the above range.
To control the temperature coefficient τ _f of the resonance frequency from the negative side to the positive side with a large relative permittivity ε _{r and a} large no-load Q, the molar fraction x of BaO is 0.1818 ≦ x ≤
The range of 0.19 and the total molar fraction y of TiO ₂ and ZrO ₂ are preferably in the range of 0.81 ≦ y ≦ 0.8182.

Further, when replacing TiO ₂ with ZrO ₂ , if the replacement amount becomes excessively large, the no-load Q becomes small and the temperature coefficient τ _{f of the} resonance frequency becomes large, so that z is set in the above range. . By substituting a specific amount of TiO ₂ with ZrO ₂ , the temperature coefficient τ _f of the resonance frequency can be reduced, and the temperature coefficient τ _f can be controlled from the negative side to the positive side by the component composition ratio.

An example of a preferred method for producing the dielectric ceramic composition of the present invention will be described below. A predetermined amount of each of the starting materials of barium carbonate, titanium oxide and zirconium oxide is wet-mixed together with a solvent such as water or alcohol. Subsequently, after removing water, alcohol and the like, the mixture is pulverized and calcined at 900 to 1100 ° C. for about 5 hours in an oxygen-containing gas atmosphere (for example, air atmosphere). The calcined product thus formed is pulverized, and an organic binder such as polyvinyl alcohol is added and mixed to homogenize, dried, pulverized, and pressed (100 to 1000 kg / cm ² ). Thereafter, the molded product is placed in an oxygen-containing gas atmosphere such as air at 1250 to 14
By firing at 20 ° C., a dielectric ceramic composition represented by the above composition formula is obtained.

The dielectric ceramic composition thus obtained can be processed as it is or as necessary into an appropriate shape and size to obtain a dielectric resonator, a dielectric substrate for microwave IC, a dielectric adjusting rod. And the like. Particularly, when a dielectric resonator used in a microwave band is used, an excellent effect is exhibited.

In addition, barium, titanium and zirconium
As raw material, BaCO_Three, TiO _Two, ZrO_TwoEtc.
In addition, carbonates, nitrates, and hydroxyls that become oxides during firing
And the like.

[0013]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Example 1 0.1818 mol of barium carbonate (BaCO ₃ ) powder, 0.8141 mol of titanium oxide (TiO ₂ ) powder and 0.0041 mol of zirconium oxide (ZrO ₂ ) powder were put into a ball mill together with ethanol and wet-mixed for 10 hours. . The mixture was taken out of the ball mill, the ethanol of the solvent was evaporated, and the mixture was pulverized for 1 hour using a crusher. The pulverized material was calcined at 1000 ° C. in an air atmosphere, and then pulverized again with a crusher for 1 hour to obtain a calcined powder.

Next, an appropriate amount of polyvinyl alcohol is added to the calcined powder.
After adding and uniformly mixing the alcohol solution, the diameter is 15 mm.
φ, 5.5mm thick disk-shaped pellets, air atmosphere
Baking and sintering at 1380 ° C for 2 hours under the air
A body porcelain composition was obtained. The porcelain composition thus obtained is applied
Measured by dielectric resonance method after cutting to appropriate size
And the resonance frequency f₀(2-6 GHz) no-load Q
And relative permittivity ε _rI asked. In addition, temperature dependence of the resonance frequency
For viability, measured in the range of -40 to 50 ° C.
Coefficient τ_fI asked. Table 1 shows the results.

Examples 2 to 6 A dielectric ceramic composition was produced in the same manner as in Example 1 except that the mixing ratio of barium carbonate, titanium oxide and zirconium oxide was changed. And the electrical characteristics were measured. Table 1 shows the results.

Comparative Examples 1 to 4 Dielectric ceramic compositions were produced in the same manner as in Example 1 except that the amounts of starting materials used were changed, and the electrical characteristics were measured. Table 1 shows the results.

[0017]

[Table 1]

[0018]

The dielectric porcelain composition of the present invention has an unloaded Q
In addition to having a large relative dielectric constant, it has an excellent stability of the temperature coefficient of the resonance frequency and can control the temperature coefficient from the negative side to the positive side, so that it is suitable as a dielectric ceramic material. Further, using the dielectric porcelain composition of the present invention,
For example, when used as a microwave dielectric resonator, there is an advantage that the reliability of the receiver can be greatly improved and the receiver can be downsized.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-54941 (JP, A) JP-A-6-252007 (JP, A) JP-A-2-220304 (JP, A) JP-A-6-205 333426 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01P 7/10

Claims (1)

(57) [Claims] 1. The composition formula: xBaO-y [(1-z) TiO
₂ · zZrO ₂ ] (where, 0.1818 ≦ x ≦ 0.2,
0.8 ≦ y ≦ 0.8182, 0 <z ≦ 0.1, and x
+ Y = 1. ) And the temperature coefficient τ of the resonance frequency
_A dielectric porcelain composition comprising barium, titanium, zirconium and oxygen capable of controlling _f from the negative side to the positive side .