JPS63303844A - Composition of dielectric porcelain - Google Patents

Abstract

PURPOSE:To obtain the composition of dielectric porcelain which has high dielectric constant and large unloading Q and is excellent in temp. stability of resonance frequency by constituting it of the conjugated oxide of Ba, Co, Zn and Nb wherein the contents incorporated as BaO, CoO, ZnO and Nb2O3 are specified respectively. CONSTITUTION:The composition of dielectric porcelain of this invention consists of conjugated oxide incorporating 59.0-63.2wt.% BaO, 1.6-6.5wt.% CoO, 1.7-7.0wt.% ZnO and 26.5-31.0wt.% Nb2O3. This conjugated oxide is produced by the following method. In other words, BaCO3, CoO, ZnO and Nb2O5 used as a starting raw material are weighed so that these are regulated to the above- mentioned weight ratio and mixed in a wet method with a ball mill. Then after dehydrating and drying the mixed raw material, it is calcined at 1,000-1,200 deg.C and furthermore coarsely crushed and pulverized in the wet method with the ball mill. Then after this fine powder is pulverized in the wet method with the ball mill, dehydrated and dried, a binder is added thereto at proper amount and the mixture is granulated and molded to obtain the composition of dielectric porcelain consisting of the conjugated oxide.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dielectric ceramic composition, and particularly to a dielectric ceramic composition having a high dielectric constant, a high no-load Q, and stable temperature characteristics. It is.

[Conventional technology]

Dielectric ceramics have been applied to dielectric resonators and impedance matching in microwave circuits. In recent years, with the advancement of technology that applies microwave circuits, especially for satellite broadcasting and automatic military telephones, stabilization of the oscillator frequency,
Dielectric filters: Dielectric ceramics with high dielectric constant and low loss are being actively used for miniaturization.

Conventionally, these dielectric elements include (ZrSn)TiO
a. Many Ti01-based materials such as 71gTi03-CaTiOs have been used.

[Problem that the invention seeks to solve]

However, these dielectrics have many problems in practical use, such as large dielectric loss, poor stability of temperature characteristics of resonance frequency, and large variations.

(Means for Solving the Problems) In order to solve all the above-mentioned problems, in the present invention, 59.0 to 63.2 weight % as BaO and 1.6 to 6.5 weight % as Coo are used. , 1.7 to 7 as ZnO.
0 significant%, 26.5-31.0% by weight as NbtOs
The present invention provides a dielectric ceramic composition containing the following.

As a result, as will be described later, it is possible to provide a material with a high dielectric constant, a large no-load Q, and excellent temperature stability of the resonant frequency.

〔Example〕

The present invention will be explained based on examples.

As starting materials, commercially available BaCO3, Coo, ZnO
and Nb2O were weighed so as to have the composition shown in Table 1 after final sintering, and mixed in a ball mill for 20 hours.

This mixed raw material is dehydrated and dried at 1000°C to 1200°C.
After that, the calcined product was roughly pulverized and further wet-pulverized in a ball mill. This crushed mud was then dehydrated and dried. An appropriate amount of binder was added to the powder thus obtained and granulated, with a diameter of 12.3
Formed into a cylinder shape with mφ and height of 7fl and heated at 1350℃~1
It was baked at 600°C for about 2 hours.

Next, the dielectric ceramic obtained as described above was processed to have a diameter of 101φ and a height of 5fi, and the dielectric constants ε and Q at 25° C. and 7 GH2 were determined. The measurement method was performed using a TEo++ mode of a resonator configured by sandwiching the cylindrical dielectric material between two parallel metal plates. Further, the resonant frequency temperature coefficient TCf was determined from the change in the resonant frequency when the temperature changes from -40°C to +80°C. In this way, Table 1
The values shown are obtained.

Back of margin 1 *Out of range As is clear from Table 1, the reasons for limiting the composition range in the present invention are as follows.

That is, BaO is less than 59.0% by weight or 63.0% by weight.
If it exceeds 2% by weight, sintering properties will be poor and Q will decrease.

Further, if Coo is less than 1.6% by weight, the temperature coefficient TCf becomes large, and if it exceeds 6.5% by weight, sinterability is poor and Q is decreased.

When ZnO is less than 1.7% by weight, Q is low (7.0% by weight)
If the temperature coefficient TCf is exceeded, the temperature coefficient TCf becomes too large.

Furthermore, Nb, O, is less than 26.5% by weight or 31% by weight.
If it exceeds 0% by weight, sinterability will deteriorate and Q will decrease.

The dielectric ceramic thus obtained was used as a dielectric resonator with 12
When used to stabilize the frequency of a local oscillator in a BS converter in the GHz band, good characteristics were obtained.

The dielectric ceramic composition of the present invention has a high Q value not only in the microwave band but also in low frequencies around lM)Iz, has a high dielectric constant, and has a small temperature coefficient, so it is suitable as a material for ceramic capacitors. It was confirmed that it has good properties in terms of applications.

〔Effect of the invention〕

The present invention can provide a dielectric ceramic composition that has a high dielectric constant, a large no-load Q (and also has excellent temperature stability of the resonance frequency).

Claims (1)

[Claims] (1) An oxide containing Ba, Co, Zn, and Nb, with a content of 59.0 to 63.2% by weight as BaO, 1.6 to 6.5% by weight as CoO, and 1.7 to 7% as ZnO. ．．
A dielectric ceramic composition characterized in that the content of Nb_2O_5 is in the range of 26.5 to 31.0% by weight.