JPH06349325A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composition excellent in no load Q, dielectric constant and stability of temperature coefficient of resonant frequency and capable of controlling the temperature coefficient from a negative side to a positive side by including mainly BaO and TiO2, and substituting a part of TiO2 with a specific quantity of ZrO2. CONSTITUTION:Predetermined quantities of CaCo3, TiO2, ZrO2 and a solvent are mixed in a wet method. After removal of the solvent, the resultant composition is pulverized, followed by calcination at 900-1100 deg.C in the atmosphere of oxygen-containing gas. After the calcinated composition is pulverized, it is added with an organic binder, followed by drying and pulverizing, to be molded under pressure of 100-1000kg/cm<2>. Thereafter, the composition is baked at 1250-1420 deg.C in the atmosphere of oxygen-containing gas, thus obtaining a dielectric porcelain composition composed of Ba, Ti, Zr and O and expressed by a formula: xBaO-y[(1-z)TiO2.zZrO2], wherein 0.1818<=x<=0.2, 0.8<=y<=0.8182, 0<z<=0.1, and x+y=1.

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 adjusting rod, etc., in addition to the dielectric resonator material.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a compact and high-performance dielectric resonator is required. The dielectric ceramic composition used for such a dielectric resonator has a large relative permittivity ε _r , a large unloaded Q, and good stability of the temperature coefficient τ _f of the resonance frequency. Characteristics are required.

Conventionally, a BaO--TiO ₂ -based dielectric ceramic composition has been known as a dielectric resonator having excellent characteristics. For example, in JP-A-56-102003 and JP-A-57-21010, BaO-TiO is disclosed.
_{2 -Nd 2 O 3 -Bi 2 O} 3 system, BaO-TiO ₂ -S
A m ₂ O ₃ —Nd ₂ O ₃ based porcelain composition has been proposed.
However, the characteristics are not yet sufficient, and there is room for improvement in terms of reproducibility of electrical characteristics.

When used as a material for a dielectric resonator in various fields, the temperature coefficient τ of the resonance frequency is
There is a need for a dielectric ceramic composition having a problem of _{f, a} large relative permittivity ε _r and a large unloaded Q, and an excellent temperature coefficient τ _f . In particular, the temperature coefficient τ _f of the resonance frequency in the Ba—Ti system is +4 to +10 ppm / ° C., which is large on the positive side. Therefore, a dielectric ceramic composition in which the temperature coefficient τ _f is controlled to be shifted to the negative side is It has been demanded. In order to achieve this, it has been attempted to add other elements to the BaO—TiO ₂ system or replace them with other elements, but the relative dielectric constant is small and the unloaded Q is still small. It wasn't enough.

[0005]

An object of the present invention is to provide a dielectric ceramic composition having excellent characteristics as a dielectric resonator material, particularly a high dielectric constant, a large no-load 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 the negative side to the positive side.

[0006]

The present invention provides a compositional formula, x
BaO-y [(1-z) TiO ₂ · zZrO ₂ ] (in the formula, 0.1818 ≦ x ≦ 0.2, 0.8 ≦ y ≦ 0.81
82, 0 <z ≦ 0.1, and x + y = 1. ) Relating to a dielectric ceramic composition composed of barium, titanium, zirconium and oxygen.

According to the present invention, a specific amount of BaO, TiO₂The Lord
As a component, TiO₂Part of ZrO ₂Replace a specific amount with
To improve the drawbacks of the conventional dielectric ceramic composition.
It is based on the knowledge that

In the present invention, the molar fraction x of BaO is larger than 0.2, or the molar fraction x of BaO is 0. 1
If it is smaller than 818, the temperature coefficient τ _f of the resonance frequency becomes large, so that the mole fraction x of BaO and TiO ₂ and Zr.
The total mole fraction y with O ₂ is set in the above range.
Further, in order 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 mole fraction y of TiO ₂ and ZrO ₂ is preferably 0.81 ≦ y ≦ 0.8182.

If the amount of substitution for replacing TiO ₂ with ZrO ₂ is excessively large, the no-load Q becomes small and the temperature coefficient τ _{f of the} resonance frequency becomes large. Therefore, z is set within the above range. . The specific amount of TiO ₂ can be reduced the temperature coefficient tau _f of the resonance frequency by replacing ZrO _2, it is possible to control the temperature coefficient tau _f from the negative to the positive side by the component composition ratios.

An example of a suitable method for producing the dielectric ceramic composition of the present invention will be described below. Starting materials of barium carbonate, titanium oxide, and zirconium oxide are wet-mixed in predetermined amounts with a solvent such as water or alcohol. Then, after removing water, alcohol, etc., it is pulverized and calcined in an oxygen-containing gas atmosphere (for example, an air atmosphere) at 900 to 1100 ° C. for about 5 hours. The calcinated product thus formed is crushed, then an organic binder such as polyvinyl alcohol is added and mixed to homogenize, dried, crushed and pressure-molded (pressure 100 to 1000 kg / cm ² ). Then, the molded product was subjected to 1250 to 14 under an oxygen-containing gas atmosphere such as air.
By firing at 20 ° C., the dielectric ceramic composition represented by the above composition formula is obtained.

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

In addition, barium, titanium, zirconium
As a raw material, BaCO₃, TiO ₂, ZrO₂And others
In addition, carbonates, nitrates, and hydroxides that become oxides when fired
Compounds and the like can be used.

[0013]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. 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 in a ball mill together with ethanol and wet-mixed for 10 hours. . The mixture was taken out of the ball mill, the solvent ethanol was evaporated, and the mixture was pulverized with a muller for 1 hour. The pulverized product was calcined at 1000 ° C. in an air atmosphere, and then pulverized again by a mashing machine for 1 hour to obtain a calcined powder.

Then, an appropriate amount of polyvinyl alcohol was added to the calcined powder.
After adding the rucor solution and mixing it uniformly, the diameter is 15 mm.
φ, 5.5mm thick disc-shaped pellets are molded into an air atmosphere.
Dielectric of the present invention by firing and sintering under air at 1380 ° C. for 2 hours
A body porcelain composition was obtained. The porcelain composition thus obtained is suitable
Measured by the dielectric resonance method after cutting to the appropriate size
And the resonance frequency f₀No load Q at (2 to 6 GHz)
And relative permittivity ε _rI asked. In addition, the temperature dependence of the resonance frequency
For the existence, measure in the range of -40 to 50 ° C
Coefficient τ_fI asked. The results are shown in Table 1.

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

Comparative Examples 1 to 4 Dielectric ceramic compositions were produced in the same manner as in Example 1 except that the amount of the starting materials used was changed so that the dielectric ceramic compositions had the compositions shown in Table 1. The electrical characteristics were measured. The results are shown in Table 1.

[0017]

[Table 1]

[0018]

The dielectric ceramic composition of the present invention has an unloaded Q value.
Not only is it large, but also has a reasonably large relative permittivity, the stability of the temperature coefficient of the resonance frequency is excellent, and the temperature coefficient can be controlled from the negative side to the positive side, so it is suitable as a dielectric ceramic material. Further, using the dielectric ceramic 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 size can be reduced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masataka Fujinaga 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture Ube Inorganic Materials Research Laboratories, Inc.

Claims (1)

[Claims] 1. A composition formula, xBaO-y [(1-z) T.
iO ₂ · zZrO ₂ ] (in the formula, 0.1818 ≦ x ≦ 0.
2, 0.8 ≦ y ≦ 0.8182, 0 <z ≦ 0.1, and x + y = 1. ) A dielectric ceramic composition comprising barium, titanium, zirconium, and oxygen represented by the formula: