JPS6054725B2 - dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dielectric ceramic composition that takes advantage of its high dielectric constant and is used in small-sized, large-capacity capacitors and the like.

Conventional Structures and Problems Conventionally, BaTiO3-based porcelains have been widely put into practical use as high-permittivity porcelains with a dielectric constant of 1000 or more, but the larger the dielectric constant, the greater the temperature change in the dielectric constant.

When the dielectric constant becomes approximately 4000 or more at a temperature of 20℃, the capacitance change rate becomes -40% or more in the temperature range of 20 to 85℃, and the dielectric constant changes greatly depending on the applied voltage, so the capacitance changes. It has been difficult to fabricate a small, large-capacity capacitor using a high dielectric constant because it is necessary to allow a large margin for the initial value of .

Purpose of the Invention The present invention has experimentally confirmed that the above phenomenon occurs to a negligible extent especially in ceramic capacitors, and
We have developed a dielectric ceramic composition that does not easily cause such phenomena,
As a result, it is possible to provide a high-performance dielectric ceramic composition that can be used in a volume that is approximately one-fifth that of a conventional barium titanate-based dielectric.

Structure of the invention The present invention contains 35 to 60 wt% of SrTiO3,
caT1o3 is 2.0 to 7.0 wt%, PbTiO.

is 15 to 35 Wt%, Bi. O.・TiO. is 18~
A composition of 35 wt% forms a composition of 100 wt%, and SiO. 0.1 to 0.5 Wt%, Nb, q 0.1 to 0.5 Wt%.
It is added in an amount of 1 to 1.0 wt%. It is an object of the present invention to provide a dielectric ceramic composition which exhibits excellent properties such as a temperature characteristic that can be freely changed by changing the proportion of the above-mentioned composition, a high dielectric constant, a low dielectric integral loss, and a high withstand voltage. can.

DESCRIPTION OF EMBODIMENTS A dielectric ceramic composition according to an embodiment of the present invention will be described below.

J The method for manufacturing the dielectric ceramic composition of this example will be explained.

First, as a sample preparation step, equimolar SrC0 was added.

and TiO2, Ca0. and Ti0 and Pb06Ti0, respectively, and then heated to 10 μC using an Elema heating element.
Temporarily baked at 12°C for 2 hours. Thereafter, each fired product is crushed, the particle size is sorted, and it is confirmed by X-rays that each fired product has become a single solid solution. Thereafter, each solid solution is mixed using a urethane-lined pot mill and a urethane-lined ball to prevent contamination of impurities. Then, the mixture was heated to 11,000C in an electric furnace using an Elema heating element.
The mixture is held at ~1200° C. for 2 hours to evaporate, and as final molding, a disk of 17φ×1 CfwR is pressure-molded at a pressure of about 1000 kg/Clt. Then, a silver electrode solution is applied to both sides of the finally obtained dielectric ceramic composition and baked at 800° C., and the electrical properties of the dielectric ceramic composition are measured. The dielectric ceramic composition of the present invention has the following composition.

That is, SrTlO3 is 35 to 60 Wt%, CaTiO
J is 2.0 to 7.0 W't%, PbTlO3 is 15 to 3
5Wt%, Bi2O3●TiO2 is 18 to 10%
0 Wt% composition, and 0.1% of SlO2 was added to the composition.
~0.5Wt%, 0.1~1.0Wt% Nb2O5
It was added. In the present invention, SrTi has a high dielectric constant of 320 and a temperature coefficient of 1**3200×1σ/°C.
The reason why a single solid solution of O3 is used is that it works to improve the dielectric constant and dielectric change rate to produce reproducible porcelain, and it also works to improve the dielectric loss at high frequencies.

However, using a large amount of SrTiO3 leads to a decrease in dielectric constant. Further, when a large amount of CaTiO3 is contained, the dielectric constant becomes high and dielectric loss at high frequencies is improved.

Further, the dielectric constant becomes high when a large amount of PbTiO3 is included. However, PbTiO3 has the effect of increasing the rate of temperature change and self-heating. Also, Bi2O3 and TiO2 are
If it is present in large amounts, it lowers the dielectric constant and makes it impossible to produce good quality porcelain.

SiO2 has the effect of stabilizing the rate of temperature change, and N
b2O. has the effect of improving dielectric loss.

Next, each composition is mixed in the proportions shown in Table 1.

Sample No. 3 has CaTiO3 less than 2.0 Wt%, Sample No. 4 has CaTiO3 greater than &α%, Sample No. 5 has PbTiO3 less than 15 Wt%, and Sample No. 6 has PbTiO3 greater than 35 Wt%. , Sample No. 7 has a Bl2O3.TiO2 content of less than 18 Wt%, and Sample No. 8 has a 5B1203.TiO2 content of more than 35 Wt%. Further, sample number 14 does not contain SiO2, sample number 15 contains more than 0.5 Wt% of SiO2, and sample number 16 contains Nb2O. is not included,
Sample number 17 contains (Bl.O5 is greater than 1.0 wt%, sample number 18 contains SiO and N)05 (
It's something that doesn't exist. That is, sample numbers 9 to 13 are the dielectric ceramic compositions in this example. Next, Table 2 shows the characteristics of the dielectric device compositions of sample numbers 1 to 18 shown in Table 1.

As shown in Table 2, when SrTiO3 is greater than 60wt%, the dielectric constant decreases as in sample number 1, and 35WL%
If it is less than that, the dielectric loss deteriorates as in sample number 2.

When CaTiO3 is more than 7.0 wt%, the temperature change rate deteriorates as in sample number 4, and when it is less than 2.0 wt%, dielectric loss at high frequencies deteriorates. When PbTiOJ is more than 35 Wt%, the temperature change rate and self-heating deteriorate as in Sample No. 6, and when it is less than 15 WL%, the dielectric constant decreases as in Sample No. 5. Sample No. 8, in which Bl2O3.TiO2 is more than 35 Wt%, has a lower dielectric constant and poor sintering condition, and if it is less than 35 Wt%, the rate of temperature change deteriorates, as in Sample No. 7. Also, SiO2 is 0.5Wt
If it is larger than 0.1 Wt%, the temperature change rate on the low temperature side deteriorates as in sample number 15, and if it is less than 0.1 Wt%, sample number 1.
As shown in 4.18, the rate of temperature change on the high temperature side worsens.

Nb2O. If it is larger than 1.0 Wt%, the dielectric loss deteriorates as in sample number 17, and if it is less than 0.1 Wt%, the temperature change rate deteriorates as in sample number 1-18. However, sample numbers 9 to 1, which are dielectric ceramic compositions of this example,
No. 3 has a high dielectric constant, good dielectric loss and temperature change rate, and low self-heating, and can be used for small-sized, large-capacity capacitors with excellent characteristics.

In this example, SrTiO3 having an equimolar composition ratio was used in calculation, but good characteristics could be obtained even if the ratio was shifted by around 0.5 molar.

Effects of the Invention As described above, the present invention provides SrTiO3, Ca
TiO,, PbTlO,, Bi2O3・TiO2, Si
Q. , and Nb2O at a certain ratio, it is possible to have a high dielectric constant, low dielectric loss, good temperature change rate, and low self-heating.

Claims (1)

[Claims] 1 Single solid solution SrTiO_3, CaTiO_3, P
bTiO_3 as a component, and the above SrTiO_3 is 3
5 to 60 wt%, the above CaTiO_3 is 20 to 70 wt%
%, the above PbTiO_3 is 15 to 35 wt%, and Bi_
01 to 0.5 w of SiO_2 to 100 wt% of a composition consisting of 18 to 35 wt% of 2O_3 and TiO_2.
A dielectric ceramic composition containing 01 to 10 wt% of Nb_2O_5.