JPH0475182B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is applicable to the micro frequency region, particularly the X-
The present invention relates to a method for firing a dielectric ceramic composition that is applied in a frequency range of band or higher, exhibits a high dielectric constant and no-load Q in these frequency ranges, and has stable temperature characteristics.

<Prior Art> In recent years, with the development of communication networks, the frequency range used has expanded to include microwaves. In connection with this, dielectric ceramics are applied to dielectric resonators, microwave integrated circuit boards, impedance matching of various microwave circuits, etc. in the microwave frequency range.
Especially recently, a large number of filters, guns, or FET microwave oscillators are required to stabilize the frequency, and the demand for them is increasing.

However, as a recent general trend, miniaturization of microwave circuits is desired. The size of this microwave circuit is based on the wavelength of electromagnetic waves, and when electromagnetic waves propagate in a three-dimensional microwave circuit using a dielectric, the wavelength is λ ₀ compared to the wavelength in vacuum. When the dielectric constant is ε, it becomes λ ₀ /ε. Therefore, the larger ε is, the smaller the circuit element can be realized. Therefore, it has been strongly desired to provide a dielectric ceramic composition that has low loss, stable temperature characteristics, and a high dielectric constant.

In response to these demands, Sr(Ni _1/3 Nb _2/3 )O ₃ −Ba has a high dielectric constant, low loss, and stable temperature characteristics that can be applied to the microwave region.
A (Ni _1/3 Nb _2/3 )O-based high frequency dielectric ceramic composition was proposed as disclosed in Japanese Patent Application No. 1983-238630.

The present invention aims to provide a firing method that can further improve the dielectric constant ε and no-load Q characteristics of such a ceramic composition.

<Means for solving the problems> The present invention involves firing a mixed powder consisting of BaCO ₃ , SrCO ₃ , NiO, and Nb ₂ O ₅ in an atmosphere of 100% oxygen.
A Sr (Ni _1/3 Nb _2/3 ) O ₃ -Ba (Ni _1/3 Nb _2/3 ) O ₃ based high frequency dielectric ceramic composition is formed.

<Example> Test values of the present invention will be explained.

``Sample'' The starting materials are BaCO ₃ with a purity of 99.9% or more,
SrCO ₃ , NiO, and Nb ₂ O ₅ were weighed according to each composition, mixed with distilled water, and ground in a ball mill for 24 hours. After drying this, 1000
It was calcined for 2 hours at ~1200°C and ground for an additional 24 hours. Next, it was granulated into a shape of φ11.3-18, compression molded, and then fired at a temperature in the range of 1500°C to 1650°C.

<Results> (1-x)Sr produced by the above method
(Ni _1/3 Nb _2/3 ) O ₃ −xBa (Ni _1/3 Nb _2/3 ) O ₃ based dielectric ceramic composition in the range of x=0 to 1.00,
During the firing, measurements were taken of those fired normally in the air and those fired in a 100% oxygen atmosphere, and their characteristics were compared, and the results shown in Figures 1 and 2 were obtained.

FIG. 1 compares the theoretical density and actual density for each composition. Here, the density of the normally fired product is 97.0 to 98.5% of the theoretical density.
However, those fired in a 100% oxygen atmosphere had a density of 99.5% or more of the theoretical density.

In addition, as a result of investigating the dielectric properties for each composition,
As shown in Figure 2, compared to those fired normally, those fired in a 100% oxygen atmosphere increase to the theoretical density, have a maximum relative dielectric constant ε of 2%, and a maximum no-load Q characteristic. It rose by 20%. i.e. oxygen
For those fired in a 100% atmosphere, the relative dielectric constant ε reaches its maximum at x = 0.7, and ε = 38, and the no-load Q
was maximum at x=0.5 and Q=11500. This indicates that the degree of crystallinity is an important factor for both the dielectric constant ε and the unloaded Q.

On the other hand, there was no noticeable difference in the resonance frequency temperature coefficient τ depending on the firing atmosphere. This is because the temperature coefficient τ strongly depends on the composition itself.

<Effects> As described above, the present invention provides BaCO ₃ , SrCO ₃ ,
Sr(Ni _1/3 Nb _2/3 ) O ₃ is produced by firing a mixed powder consisting of NiO and Nb ₂ O ₅ in an atmosphere of 100% oxygen.
- It is possible to improve the dielectric constant ε and no-load Q characteristic of the Ba(Ni _1/3 Nb _2/3 ) O ₃ based high frequency dielectric ceramic composition, and therefore it is suitable for use in the microwave frequency region, especially in the X- This has an excellent effect of providing a dielectric composition material that is effective in the frequency range above the band.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between composition and density, Figure 2 is a graph showing the relationship between composition and density.
The figure is a graph showing the relationship between composition and dielectric properties.

Claims (1)

[Claims] _{1 Sr ( Ni 1/3}
1. A method for firing a dielectric ceramic composition, characterized in that a high frequency dielectric ceramic composition based on Nb 2/3 ) O _{3 −Ba} (Ni _1/3 Nb _2/3 ) O ₃ is formed.