JPS6057163B2 - High permittivity porcelain dielectric composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic dielectric composition with a high dielectric constant, and particularly to a ceramic dielectric composition which has an extremely high dielectric constant and a small rate of change in dielectric constant with temperature, and is suitable for use in multilayer capacitors. It is something.

Conventionally, barium titanate (BaTi0a) and bismuth oxide (B1.

The main component is tin oxide (SnO2), titanium oxide (TiO2), or zirconium oxide (
ZrO2) is added, but all of them have a temperature change rate of ±30°C in the temperature range of -30°C to +85°C.
When it is within 10%, the dielectric constant becomes as low as 2,000 or less, and in the case of a dielectric constant on the order of 2,000, the temperature change rate of the dielectric constant can only exceed ±10% in the above temperature range. On the other hand, BaTiO3 and Bi are used as porcelain dielectric compositions that solve this problem.

Heni, Nb2q, and CeO. Orshi. Add 00 and
A device which achieves a dielectric constant temperature change rate within ±10% and a dielectric constant of 3000 to 3500 is disclosed in Japanese Patent Publication No. 55-2140 Sae.

However, there is a problem that the Bi203 contained in such compositions will evaporate if high firing temperatures are employed in making multilayer capacitors, thereby damaging the electrodes, and therefore the B1.03. Compositions containing such components were unsuitable for use in multilayer capacitors.

The present invention has been made against the background of such circumstances, and its object is to provide a porcelain material suitable for use in multilayer capacitors, which has flat dielectric constant temperature characteristics and also has a high dielectric constant. The objective is to provide a dielectric material.

Therefore, the high permittivity ceramic dielectric composition according to the present invention is made of high purity BaT10095-- which is formed from barium carbonate (BaCO3) with a purity of 99% or more and titanium oxide (TiO0) with a purity of 99% or more. 99% and cobalt oxide (
C0003) 0.05-0.5% and niobium oxide (Nb
,0,)0.5-2% and cerium oxide (Ce02)0
．． 05-0.5% and TIO.

(all percentages are based on weight).The porcelain dielectric composition according to the present invention has a flat dielectric constant temperature characteristic. In particular, it is easy to obtain a dielectric constant whose temperature change rate is within ±10% when the dielectric constant is referenced to +25°C (7) within the temperature range of -30°C to +80°C. Moreover, at the same time, its dielectric constant can easily be 300.
It can be made greater than 0.

Moreover, in the case of the porcelain dielectric composition obtained by firing according to the present invention, B1.

Since it does not contain any evaporative components such as 0.03 or yen, it does not damage the electrodes at all even if a high firing temperature is used, and therefore it can be suitably used for multilayer capacitors.

In addition, in the present invention, it is first necessary to blend high-purity BaTlO3 into the composition at a ratio of 95 to 9% by weight, preferably 97 to 9% by weight; If the temperature is too high, problems such as a significant decrease in the dielectric constant or a significant change in the dielectric constant with temperature will occur.

This high-purity BaTlO3 can be made from conventional BaTi
BacO3 with O3 of about 97%? It is formed using highly purified BacO3 and TiO2, each having a purity of 99% or more, preferably 99.5% or more. High purity BaTiO3 can only be obtained by using such a high purity starting material. Also,
CO2O3 and Nbl. O
5 is a component that flattens the rate of change in brownness of dielectric constant; CO2O3 is 0.05 to 0.5%, preferably 0.09 to 0.4%; Nb2O5 is 0.5 to 2%. %, preferably 0.9 to 1.5% (both based on weight). In addition, CO2O3 is
If it is less than 0.05%, the temperature change rate of the dielectric constant becomes large, and if it is more than 0.5%, the dielectric constant becomes low.
Also, Nb2O. However, when it is less than 0.5%, the problem of poor sintering occurs, and on the other hand, when it is more than 2%, there is a problem that the temperature change rate of the dielectric constant becomes large. Furthermore, CeO2 in the composition of the present invention has the effect of lowering the sintering temperature, but if its proportion is less than 0.05%, sintering will be poor, and if it exceeds 0.5%, the temperature of the dielectric constant will decrease. The rate of change is large.

Therefore, the proportion of CeO2 is 0.05-0.5% by weight,
Preferably 0.09-0. It needs to be the heel volume%. Furthermore, like CeO2, TlO2 contributes to lowering the firing temperature, but if its proportion is too large, it lowers the dielectric constant and increases dielectric loss (Tanδ), so TlO2 is added at 1.5% by weight. It is necessary to make the content ratio up to
Among them, 0.2 to 1. By containing it in the proportion of filtration rate, its effective effect is exhibited. Furthermore, this Ti
The amount of O2 can be introduced by combining excess TiO2 with BacO3 when forming the high-purity BaTiO3, or by separately incorporating the required amount of TiO2 into the composition. It can be introduced. Thus, the present invention provides a specific Ba
TiO3, CO2O3, Nb2O. ,CeO2,Ti
By configuring the porcelain dielectric material in a predetermined ratio with O2, it was possible to exhibit the many excellent characteristics described above.

Examples will be given below to clarify the present invention more specifically, but it goes without saying that the present invention is not limited in any way by the description of these Examples. Note that all parts and percentages in the examples are expressed on a weight basis. Examples The raw materials for each component were wet-mixed uniformly in a ball mill so that the proportions shown in Table 1 were obtained, and then calcined at 900 to 1100°C for 3 hours to carry out a chemical reaction, and then mixed again. It was ground in a ball mill until the average particle size was about 1 micron.

In addition, in order to form a high purity BaTiO3 component, BacO3 with a purity of 99.5% and TiO with a purity of 99.9% are used.
, was used and wet mixed with other ingredients in the ball mill. Next, after drying this mixture, an appropriate amount of polyvinyl alcohol was added as a binder, and it was molded at a pressure of about 1 ton/d to a diameter of 16 m/Tr.
l. A disc-shaped molded product with a thickness of 0.5 m/Wl was produced.

Furthermore, about 1350
After performing the main firing operation for 3 hours at a temperature of ~1400°C, the obtained fired product was made into a sample by baking silver electrodes on both sides, and then heated at 300°C @ 1% per sample thickness. (2) After conducting a life test by applying V, various electrical characteristics of each were measured and the results are shown in Table 2. As is clear from the results in Tables 1 and 2, all of the compositions according to the present invention have a high dielectric constant ε of 3000 or more and a small dielectric loss (Sin δ). At the same time, it also has the property of having a small rate of change in dielectric constant with respect to temperature.

On the other hand, sample No. A composition starting from normal quality BacO3 and TiO2 having a composition substantially similar to that of 2 can only be obtained with a dielectric constant ε of about 3000,
Sample No. according to the invention. The dielectric constant ε of No. 2 was significantly inferior to 4055.

Also, CO2O3, Nb2O. , ceO2 and TiO2
The one consisting only of high-purity BaTiO3, which does not contain
．． The rate of change at +85℃ and -300C is -1 respectively.
9.8% and -32%, which was significantly inferior to the composition according to the present invention.

Claims (1)

[Claims] 1 95-99% of high-purity barium titanate formed from barium carbonate with a purity of 99% or more and titanium oxide with a purity of 99% or more, 0.05-0.5% of cobalt oxide, and 0.0% of niobium oxide. 5~2% and cerium oxide 0.05~
0.5% of titanium oxide and up to 1.5% of titanium oxide.