JPS6049151B2 - Method for manufacturing dielectric magnetic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a dielectric ceramic composition having a high dielectric constant and a small change in dielectric constant with respect to temperature.

More specifically, the present invention relates to a method for producing a dielectric ceramic composition having a high dielectric constant, a small loss angle, and a small voltage dependence of the dielectric constant.

Ba
T1O.

Although porcelain based ceramics are widely used in practical use, the larger the dielectric constant, the greater the temperature change in the dielectric constant. That is, temperature 2
When the dielectric constant becomes about 4000 or more at 0℃, the temperature 2
The capacitance change rate is -40% or more in the range of 0 to 85 degrees Celsius, and the dielectric constant changes greatly depending on the applied voltage, so it is necessary to make small and large capacitors by taking advantage of the high dielectric constant. was difficult. This is because changes due to temperature and voltage or changes over time are large, so it was necessary to allow a large margin for the initial value of the capacitance. The present invention has experimentally confirmed that the above-mentioned phenomenon occurs to a non-negligible extent especially in ceramic capacitors, and has developed a dielectric/heavy ceramic composition in which such a phenomenon hardly occurs. The present invention provides a method for producing a high-performance dielectric ceramic composition that can be used in about one-fifth of the volume compared to the case where a barium oxide dielectric is used.

The characteristics of the porcelain dielectric composition of the present invention are as follows:
It is within the range of 2 to 10 wt% 5, and by changing the proportion of the above composition, the temperature characteristics can be freely changed, and it is an excellent material with a high dielectric constant, a small loss angle, and a high withstand voltage. It shows the characteristics.

Incidentally, SrTiO3 has been known for a long time, but it is known that its dielectric constant is as high as 320 and its temperature coefficient is -3200×1 Cf/°C.

This material has conventionally been used as a temperature compensation material, but this material includes PbTlO3, Bl2O3●TiO2
By adding three components: , CaSnO3, we succeeded in increasing the dielectric constant and reducing the rate of temperature change. Also,
It is very difficult to make good porcelain using the above-mentioned single materials, and the above-mentioned substances alone are worthless as a ceramic dielectric composition, which is the purpose of the present invention.

However, the present inventors found that SrTlO3
-PbT'IO3-Bl2O3●TiO2-CaSnO
It has been discovered that a composition using a three-system solid solution can provide a porcelain dielectric composition that has not been available hitherto.

In the composition of the present invention, the use of the SrTiO3 component, which is already in a single solid solution, provides good dielectric constant and temperature change rate, and serves to produce reproducible porcelain.

Further, although the SrTlO3 component has the effect of improving the loss angle at high frequencies, if it is included in an excessively large amount, it may cause a decrease in the dielectric constant. If a large amount of the PbTlO3 component is included, the dielectric constant will increase, but this will cause an increase in the rate of temperature change.

Furthermore, if the Bi2O3/TiO2 components are contained in large amounts, they cause a decrease in the dielectric constant and also make it impossible to produce good quality porcelain. The CasnO3 component has the effect of minimizing a decrease in the dielectric constant and significantly improving the temperature change rate, but when the CasnO3 component increases significantly, the dielectric constant decreases.

The functions of each component are shown above. "However, if one or two of these components are missing, there is no effect at all in producing the desired porcelain, and when the components within this range are gathered together, the desired porcelain can be obtained. It is.

It should be noted that if the SrTiO3 component exceeds 60 Wt%, it is not preferable because the dielectric constant decreases significantly;
If it is less than %, the loss angle of high frequency becomes worse. Also, PbTl
If the O3 component exceeds 35 Wt%, the temperature change rate will deteriorate and the dielectric constant will increase, which is not preferable. On the other hand, Pb
If the T'IO component is less than 14 Wt%, the dielectric constant will drop significantly, which is not preferable. Furthermore, Bl2O3・TiO
When the content of the two components exceeds 35 wL%, the dielectric constant decreases and the sintering condition deteriorates, and when the content of the two components is less than 15 wt%, the rate of temperature change deteriorates. If the CasnO3 component exceeds 10Wt%, the dielectric constant decreases, which is undesirable, and 2Wt%
If it is less than %, the effect of improving the rate of temperature change will be poor, so it is not preferable. Furthermore, in the present invention, Bi2O3 is T
If the amount is less than iO2, it becomes impossible to obtain good porcelain. Additionally, MnO2 can be added to the above composition as an additive.
By adding within the range of 0.2 to 1.0 Wt%, there is an effect of bringing the rate of change in capacity closer to the desired range,
It also has the effect of improving the loss angle at high frequencies. 7 Here, if MnO2 is less than 0.2 Wt%, the effect of improving the high frequency loss angle is poor, and if it exceeds 1.0 W't%, it is not preferable because it lowers the dielectric constant.

Particularly, addition within the range of 0.4 to 0.8 Wt% improves the loss angle of high frequencies. Furthermore, SiO2)0.
Adding within the range of 0.05 Wt% to 1.0 Wt% has the effect of stabilizing the temperature change rate, but if it is less than 0.05 Wt%, the temperature change rate on the high temperature side (+85°C) worsens.
When it exceeds 0 Wt%, the rate of temperature change on the low temperature side (-25°C) deteriorates. And CeO2 is 0.05-0.4
Adding within the Wt% range improves the loss angle of high frequencies. Outside this range, the high frequency loss angle deteriorates. In this example, SrTiO3 was used with an equimolar composition ratio based on calculation, but good characteristics could be obtained even if the ratio was shifted by around 0.5 molar.

Next, the details of an example implemented based on such conditions will be described below.

First, as a sample preparation step, first equimolar SrcO
3 and TlO2, Pl)0(5Ti02, CaC03 and S
Mix nO2 respectively, then 10500C~120
After being calcined at 0°C for 2 hours, it was crushed and sorted into various particle sizes.

Thereafter, each material was mixed in the respective proportions as shown in Table 1 below (SrTiO3, PbTi
It was confirmed by X-rays that each solid solution of O3 and CaSnO3 was a single solid solution. In addition, an Elema heating element was used for firing. In addition, in order to prevent the mixing of impurities, wet mixing is performed using a urethane-lined pot mill and a urethane-lined ball, after which water is evaporated, and the final molding is performed using a 17φ x 1.0rT11m disc at a pressure of about 1000k91cr1. Pressure molded. In addition, the firing is performed in an electric furnace using an Elema heating element at a temperature of 1100 C ~ 1
The temperature was maintained at 250°C for 2 hours. The ceramic element thus obtained was coated with silver electrode solution on both the inner and outer surfaces, and
The electrical properties of each sample were measured by baking at ℃. The measurement results are shown in Table 2 below. In addition, CeO in Table 1
La2O3, Nd2O3, pr6Oll instead of two components
, Y2O3 can also be used to obtain good properties.

In Tables 1 and 2 above, examples within the scope of the present invention are N
O. 5 to NO tears, and the others are examples outside the range.

As is clear from the examples, good properties can be obtained with compositions within the scope of the present invention.

Especially NO. No. 7 had a high dielectric constant, a low loss angle at high frequencies (1M ratio), good temperature characteristics, and good humidity and high temperature load life. In this example, MnO2,
Although ceO2 oxide was used, good characteristics can also be obtained by using carbonate raw materials in the components of the present invention.

As described above, the present invention makes it possible to obtain dielectric porcelain that has temperature characteristics with a small capacitance change rate, has a high dielectric constant, a low loss angle, and has a good humidity and high temperature load life when the composition is within the range. It is suitable for industrial mass production.

Claims (1)

[Claims] 1. SrTiO_335, each of which is a single solid solution component
~60wt%, PbTiO_314~35wt%, Ca
SnO_32~10wt%, Bi_2O_3・TiO_
A method for producing a dielectric ceramic composition, which comprises firing a composition comprising two components in a range of 15 to 35 wt%. 2 The ratio of Bi_2O_3・TiO_2 is Bi_2O
_31.0: TiO_21.0~Bi_2O_32.0
:TiO_21.0. The method for producing a dielectric ceramic composition according to claim 1, wherein the composition is TiO_21.0. 3 SrTiO_335-60, each of which is a single solid solution component
wt%, PbTiO_314-35wt%, CaSnO
_32 to 10 wt%, Bi_2O_3・TiO_2 component range: 15 to 35 wt%, 100 wt.
%, MnO_20.2~1.0wt%, SiO_
20.05-0.5wt%, CeO_2, La_2O_
3, Nb_2O_3, Pr_6O_1_1, Y_2O_
1. A method for producing a dielectric ceramic composition, which comprises adding at least one of the above in an amount of 0.05 to 0.4 wt% and firing.