JPS5858762B2 - dielectric composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to dielectric compositions.

The objectives are dielectric constant (ε), dielectric loss (ta
An object of the present invention is to provide a composition that significantly improves the temperature stability of nδ) and ε and is suitable for a small-sized, large-capacity, high-stability capacitor material.

Compositions containing 5rTiO3゜CaTiO32MgT103 as main components have been known as high-stability porcelain capacitor materials. It was impossible to improve at the same time.

Attempts have been made to improve this by incorporating various subcomponents or synthesizing multi-element compositions.

Among them, the CaTi03-CaTiO3O5 composition maintains a large value of ε, and the value of the temperature coefficient of ε has been significantly reduced (this has been successfully achieved).

However, in this case (the temperature coefficient of ε is O±25p/℃
The value was only 80 or less.

Also 5rTi03. In order to densify compositions containing CaTiO3, MgTiO3, etc. as main components, it is necessary to sinter at a high temperature of 1300°C or higher, resulting in large variations in properties, and when processing in large quantities industrially. This had become an obstacle.

A new composition represented by O3]3[KNbO3]1-a was synthesized (thus, all of the above-mentioned drawbacks were eliminated).

In other words, the composition of the present invention has a significantly large dielectric constant and a small dielectric loss and small temperature change in the dielectric constant.Furthermore, it can be sintered at an extremely low temperature and made into porcelain, reducing variations in properties, Moreover, it has become possible to provide materials suitable for industrial mass processing.

The present invention will be explained in more detail below using an example of implementation.

Examples As starting materials for producing the porcelain of the present invention, the following materials are used:
Each powder of O5t was used.

The raw material powder used here has a chemical purity of 9.
8% or more.

A predetermined amount of each powder was weighed and mixed in a ball mill.

After filtration and drying, the mixture was pre-fired in the air at 600°C to 900°C for 2 hours, pulverized, pressure molded into a disk with a diameter of 20 mm, and then fired at 900°C to 1350°C for 2 hours.

After baking silver electrodes on both sides of the resulting porcelain, dielectric properties were measured using the following conditions.

That is, at room temperature, the dielectric constant (ε) and dielectric loss (
tan δ) was measured at a frequency of IKHz.

Further, ε was measured at 0° C. to +120° C., and the rate of change of ε with temperature was determined.

Among the results obtained, representative examples are shown in the table.

Table 1 shows the relationship between uta and dielectric properties when the composition according to the present invention is expressed as [(K-Bi)2.

Note that PbO was used as the starting material for Pb.

As is clear from Table 1, it is clear that good properties are preserved even if 802 mol% or less of (K Bi-) is replaced with Pb.

Note that when U exceeds 0.8, the dielectric constant decreases and practicality is lost.

Therefore, the valid range of a and U is 0.5≦a≦0.9,0
．． It is limited to 2≦U≦0.8.

Claims (1)

[Claims] (KNbOal)1 A composition represented by a where a and U are 0.5<, a≦0.9, 0.2≦U≦
A dielectric composition characterized in that it is within a composition range expressed by 0.8.