JP3257152B2 - 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 porcelain composition suitable as a material for a dielectric porcelain or the like.

[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. The dielectric ceramic composition used for such a dielectric resonator is required to have a large relative permittivity ε _r , a small temperature coefficient τ _{f of the} resonance frequency, a large unloaded Q, and the like. ing.

[0003] BaO is used as such a dielectric porcelain composition.
Suggestions for -TiO ₂ -Nd ₂ O ₃ based dielectric ceramic composition [Ber.Dt.Keram.Ges.55 (1978) Nr.7; JP 60
No. 35406] or BaO-TiO ₂
—Nd ₂ O ₃ —Bi ₂ O ₃ system (Japanese Patent Application Laid-Open No. 62-72558)
Has been proposed.

[0004] Recently, multilayer chip capacitors, multilayer dielectric resonators, and the like in which a dielectric ceramic composition is laminated have been developed, and lamination by simultaneous firing of the ceramic composition and internal electrodes has been performed. However, since the firing temperature of the dielectric porcelain composition is as high as 1300 ° C. to 1400 ° C., it is difficult to perform simultaneous firing with an internal electrode. It was limited to materials such as palladium and platinum. Therefore, inexpensive silver, silver-palladium or copper is used as an electrode material.
There is a need for the development of a dielectric ceramic composition that can be co-fired at a low temperature of 0 ° C. or lower.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide excellent characteristics as a dielectric material, in particular, a high dielectric constant, a large no-load Q, a small change in the resonance frequency with temperature, and when fired at a low temperature. Another object of the present invention is to provide a dielectric ceramic composition having good sinterability.

[0006]

According to the present invention, there is provided a composition formula, x
_{Bi 2 O 3 - (1-} x) GeO 2 -yCaTiO 3 wherein
0.65 ≦ x ≦ 0.90 (molar ratio), 0 < y ≦ 5.0
(Wt%). And a dielectric ceramic composition comprising bismuth, germanium, calcium titanate and oxygen.

The dielectric porcelain composition of the present invention can improve the disadvantages of the conventional dielectric porcelain composition.
By adding iO ₃ , the temperature coefficient of resonance frequency τ _f
Can be controlled from the negative side to the positive side. In the present invention, if x is excessively large or excessively small, or if y is excessively large, resonance does not occur. Therefore, x and y are set in the above ranges.

An example of a preferred method for producing the dielectric ceramic composition of the present invention will be described below. Bismuth oxide and germanium oxide starting materials are wet-mixed by predetermined amounts with a solvent such as water or alcohol. Subsequently, after removing water, alcohol and the like, the mixture is pulverized and calcined in an oxygen-containing gas atmosphere (for example, air atmosphere) at 600 to 750 ° C. for about 1 to 5 hours. The calcined product and the calcium titanate calcined powder thus obtained are wet-mixed with a solvent such as water or alcohol. Subsequently, after removing water, alcohol, and the like, pulverization is performed. Further, the mixture is mixed with an organic binder such as polyvinyl alcohol to homogenize, dried, pulverized, and then press molded (pressure 100).
１０００1000 kg / cm ² ). The obtained molded product is fired at 800 to 950 ° C. in an oxygen-containing gas atmosphere such as air to obtain a dielectric ceramic composition represented by the above composition formula.

The dielectric ceramic composition is processed into an appropriate shape and size as required, or formed into a sheet by a doctor blade method or the like and laminated by a sheet and an electrode to form a dielectric resonator or a dielectric substrate for microwaves. ,
It can be used as a material for microwave laminated devices and the like.

The raw materials of bismuth, germanium, calcium and titanium include Bi ₂ O ₃ , GeO ₂ , C ₂
In addition to aCO ₃ , TiO _2, etc., calcium titanate calcined powder or nitrate or hydroxide which becomes an oxide during firing can be used.

[0011]

The present invention will be described in more detail with reference to the following examples.
explain. Example 1 Bismuth oxide (Bi_TwoO_Three) Powder 0.857 mol, oxidation
Germanium (GeO _Two) 0.143 mol of powder in ethanol
And wet-mixed for 10 hours.
After desolvation, the solution was pulverized. The pulverized material is placed in an air atmosphere at 70
After calcining at 0 ° C, the calcined powder and calcium titanate
Into a ball mill together with ethanol
And wet mixed for 10 hours. After desolvation, the solution was pulverized.
Add an appropriate amount of polyvinyl alcohol solution to this ground product
After drying, formed into pellets with a diameter of 12mmφ and a thickness of 4mmt
Then, firing was performed at 850 ° C. for 2 hours in an air atmosphere. Like this
The porcelain composition of Example 1 obtained in Example 1 was 7 mm in diameter and about
After processing to 3mmt size, measured by dielectric resonance method
And the no-load Q at the resonance frequency (4 to 5 GHz) and the ratio
Dielectric constant ε_rAnd the temperature coefficient τ of the resonance frequency_fI asked.
Table 1 shows the results.

Examples 2 to 5 and Comparative Examples 1 to 6 Example 1 was repeated except that the amounts of bismuth oxide, germanium oxide and calcium titanate were changed as shown in Table 1.
A dielectric porcelain composition was manufactured in the same manner as described above, and the characteristics were measured. Table 1 shows the results.

[0013]

[Table 1]

[0014]

As described above, it is possible to provide a dielectric ceramic composition having a large dielectric constant, a large unloaded Q, and capable of controlling the temperature coefficient of the resonance frequency. Further, it is possible to provide a dielectric ceramic composition which can be sintered at a low temperature and can be laminated by simultaneous firing using Ag, Ag-Pd, Cu or the like as an internal electrode material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01B 3/12 318 H01B 3/12 307 C04B 35/46 H01P 7/10

Claims (1)

(57) [Claims] 1. The composition formula, xBi ₂ O _3- (1-x) GeO ₂
-YCaTiO ₃ [where, 0.65 ≦ x ≦ 0.90 (molar ratio), and 0 < y ≦ 5.0 (wt%). ] The dielectric ceramic composition which consists of bismuth, germanium, calcium titanate, and oxygen.