JPS594804B2 - High dielectric constant porcelain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new high-permittivity porcelain having a high dielectric constant, particularly a significantly small temperature change rate, and a good dielectric loss tangent at high frequencies.

It is already known that porcelain containing barium titanate as a main component has been used as a porcelain dielectric material having a high dielectric constant. These porcelains have a high dielectric constant and are often used as capacitor materials, but the higher the dielectric constant, the greater the temperature change in the dielectric constant with respect to the deviation, and the dielectric constant exceeds about 4000 (at 20 degrees Celsius). 5 The rate of change is 50% or more (at 20℃ to 85℃), and it also changes greatly depending on the voltage. It has been difficult to produce large capacitance capacitors.

10 Because it is subject to large changes due to temperature and voltage, or changes over time, it is necessary to allow a large margin for the initial value of the capacitance, so its high dielectric constant has not been fully utilized.

In addition, those with a relatively small rate of temperature change (+20 to +85°C) have a dielectric constant of 15 below ε=1500, and therefore have many drawbacks such as insufficient capacity and poor high frequency loss angle. As mentioned above, there are many improved materials mainly based on barium titanate, but there are still no defect-free materials for high-standard use (showing stable characteristics over a temperature range of -55°C to +125°C).

) is not suitable as a capacitor material, but recently materials with high dielectric constant and small temperature change rate, materials with good loss angle at high frequencies, and AC voltage characteristics under high temperature (f 16KHZ, 800Vrms/mln) There is a demand for materials with good loss angles. In addition, materials with relatively small change rates up to now include BaTi03-bismuth system, BaTi03-PbTi03 system, BaTi0
3-PbTiO3-La2O3 system PbTi03-La2
Materials such as O3・3Ti02 series are known, but these have a poor rate of change when the dielectric constant becomes high, and furthermore, the loss angle of high frequencies is poor and the Pb component is a harmful substance in terms of pollution problems (V) Furthermore, PbO and Bi2O3 etc. evaporate significantly during firing, making it difficult to obtain industrially stable porcelain. x The present invention improves these drawbacks.
The present invention provides a new high-permittivity porcelain useful as a material for small-sized, large-capacity, high-standard ceramic capacitors.

That is, the present invention adds this BaTiO3 component to the BaTiO3 component.
The weight ratio of MnO2 to the weight of O3 is 0.05 to 0.
．． 6wt01) is added and then pre-calcined at a temperature to form a single solid solution.Then, the BaTiO3 powder component with a powder particle size within the range of 0.3-2.0 μm is 94.74-99.55 mol%, and the 5Nb205 component is 0.43%. ~4.98 mol%, Bl
2O3 component 0.02 to 0.28 mol% Q composition,
This is a high dielectric constant ceramic characterized by adding 0.05 to 0.6 wt% of MnO2 component by weight.

By changing the composition ratio within the above range, the dielectric constant can be freely selected within the range of about 1500 to 3000, and the temperature change rate is ±15% in the temperature range of -55℃ to +125℃. We can provide axial ceramic capacitors.

In addition, the capacitor material obtained within the scope of the present invention has a high dielectric constant, a small capacitance temperature change rate, an extremely good high frequency loss angle (1 MHZ), and a high withstand voltage. It should be noted that BaTiO3 (M
nO3 containing) single solid solution, Nb2O5, Bi2O3, M
The reason for limiting each component such as nO2 is as follows.

That is, BaTiO3 (MnO
If the component powder (containing 2) is 99.55 mol % or more, the dielectric constant will be low, the loss angle of high frequency will be poor, and the temperature change rate will be large, which is not preferable. If it is less than 94.74 mol%, the sintering of the porcelain body becomes unstable and l) the rate of temperature change becomes large, which is not preferable.

If the Nb2O3 component is 4.98 mol% or more, the dielectric constant decreases, which is not preferable.

If it is less than 0.43 mol %, the high frequency loss angle will deteriorate, which is not preferable.

If the Bi2O3 component is 0.28 mol % or more, the loss angle of high frequencies deteriorates, which is not preferable. If it is less than 0.02 mol %, the dielectric constant decreases and the rate of change in dielectric constant with temperature deteriorates, which is not preferable.

Furthermore, when the MnO2 component is 0.6 wt% or more, the rate of temperature change becomes small, but the dielectric constant decreases extremely and the loss angle also worsens.

If it is less than 0.05 wt%, the effect of reducing the rate of change in dielectric constant with temperature becomes poor, which is not preferable.

Also, the MnO2 component contained in the BaTiO3 component is 0.
．． At 6 wt% or more, the temperature change rate becomes small, but the dielectric constant decreases extremely and the loss angle also worsens. If it is less than 0.005 wt%, the effect of reducing the temperature change rate of the dielectric constant will be insufficient, which is not preferable.

In addition, after pre-calcination and pulverization, adjusting the particle size of the BaTiO3 (MnO2-containing) raw powder to a particle size of 0.3 to 2.0 μm improves the AC voltage characteristics and uniformly changes the dielectric constant, loss angle, and dielectric constant temperature. If the foam particle size is larger than 2 μm, the dielectric constant will be low. V) Tam δ will also be large. If it is smaller than 0.3 μm, the dielectric constant temperature change rate will be poor. V) Tan δ will also be large, which is preferable. do not have.

In the present invention, the use of BaTiO3 (MnO2-containing) component powder, which has already become a single solid solution,
This is a necessary condition in order to reduce the rate of change in capacity over time, as well as the rate of change in temperature, and to obtain reproducibility.

Furthermore, it is a well-known fact that in the firing of BaTiO3-based porcelain, a trace amount of MnO2 is added to prevent reducibility.

That is, it was added to minimize the deterioration of the characteristic values of insulation resistance or loss angle. However, the present invention exhibits effects that are completely different from those of the conventional addition of MnO2.

That is, by simultaneously adding MnO2 and BaTiO3, each cue of barium titanate is held in the same position.
Moreover, it exhibits remarkable effects on properties such as dielectric constant temperature characteristics, AC voltage characteristics, and dielectric loss tangent. Also BaT
If all of the raw materials are added and mixed without being added to the iO3 component, they will easily form a solid solution with other components, and the effect of improving the properties will be lost. That is, the present invention adds the Nb2O5 component -Bi2O3-MnO to the BaTiO3 (MnO2-containing single solid solution) composition within the above composition range.
The dielectric constant is high only by adding two components simultaneously.
The capacitance change rate over a wide temperature range and also the capacitance change rate with temperature are small, the loss angle of high frequency is small, the withstand voltage is high, and the AC voltage characteristics are extremely good.

EXAMPLES The present invention will be specifically explained below with reference to Examples. In the preparation process of the example sample, first, equimolar BaCO
3, TiO2, and MnO2, and then 105
The mixture was calcined and pulverized at 0°C to 1200°C for an hour, and then adjusted to the respective particle sizes shown in the table, and then mixed in the proportions of each component.

(It was confirmed by X-rays that the BaTiO3 (containing MnO2) solid solution had become a single solid solution.

) 0.1wt (F6
of Al2O3 and SiO2 were added, respectively. ``Wet mixing was performed using a urethane-lined pot mill and a urethane-lined ball to prevent contamination of impurities.

After that, the moisture is evaporated and the molding is 15φ x 1.2m/Tn.
The disc is pressure molded at a pressure of approximately 750k9/C77f, and fired at a temperature of 1280°C to 1280°C in an electric furnace using an Elema heating element.
The test was carried out by holding at 1400°C for 2 hours. The obtained magnetic elements were coated with silver electrode solution on both sides and baked at 750°C for 15 minutes, and the electrical properties of each element were measured. In this example, BaT
iO3 was calculated to have an equimolar composition ratio, but 0.
Even if the ratio was shifted by 5 mol% or more, good characteristics could be obtained.

Although MnO2 was used in this example, the same results can be obtained with other manganese salts. Additionally, trace additions of strontium, calcium, magnesium, etc. are effective in improving properties. The following table contains a number of examples of compositions according to the invention.

In the above table, NO3-7, 11-16, 21-25,
This is an example within the scope of the present invention, and the plate and others are examples outside the scope.

All samples within the scope of the present invention can yield very fine porcelain.

In addition, the electrical properties are higher than conventional materials with the same rate of temperature change, have a higher dielectric loss factor at high frequencies, and have AC voltage characteristics (f = 16KHz, 800Vrm).
The loss rate (loss rate at 50°C) and capacity change rate over time are also good. Furthermore, the temperature change rate is small and stable over a wide temperature range. Furthermore, although not shown in the examples, the breakdown voltage is also good. Especially NO5
, 6, l3, 2l~24, 37~38 have high dielectric constants,
The dielectric constant temperature change rate is low, the dielectric loss tangent at high frequencies is small, the capacitance change rate over time is small, and the AC voltage resistance (16KHZ) is low.
The loss angle of 800Vrms/Wn50°C is extremely good.

Particularly, Yas.
The loss angle (HZ800Vrms/Mln50°C) is extremely good.

f). Sample No. 1 is not preferable for use as a capacitor because the stable radial change rate of the sample, the temperature change rate of the dielectric constant, and the AC voltage characteristics are very poor when MnO3 is not included during BaTiO3 production.

Sample black 1 to 9 are MnO included during BaTiO3 production.
This is the result of examining the allowable amount of 2. Out of range f) Jf6. l
, 2 had very poor dielectric constant temperature change rate and AC voltage characteristics, and black Nos. 8 and 9 had a small dielectric constant and a large capacitance change rate over time. Sample 10-18 is BaT containing MnO2
This is the result of investigating the powder particle size and properties of an iO3 single solid solution.

X out of range). No. 10 has a poor dielectric constant temperature change rate and AC voltage characteristic performance, while Nos. 17 and 18 have a small dielectric constant and a large capacitance change rate over time, and have a poor dielectric constant temperature change rate and AC voltage characteristics. The voltage characteristics are very poor. Sample black 19-27 is M within the range
This is the result of investigating the allowable amount of MnO3 added as an additive to a composition containing Nb2O5 and Bi2O3 within the range in a BaTiO3 single solid solution having a powder particle size of nO2.

X out of range). Nos. 19 and 20 have very poor capacitance change rates over time and are bad as capacitors. Also black 26,2
No. 7 has a low dielectric constant and a poor rate of change in dielectric constant with temperature and rate of change in capacity over time. Sample black 28-45 is MnO2 within the range
, Nb2O5,
These are the results when Bi2O3 and MnO2 were added.

The cells 41 to 45 outside the range have a poor rate of change in dielectric constant with temperature, a large rate of change in capacitance over time, and very poor AC voltage characteristics, making them poor capacitors. As described above, the present invention uses a BaTiO3 solid solution powder containing MnO2 within a range and a raw material having a powder particle size, and by adding subcomponents within a range, good characteristics can be obtained for the first time. This is something that can be done.

Claims (1)

[Claims] 1 Weight ratio to the weight of BaTiO_3 is 0.05~
In BaTiO_3 solid solution powder containing MnO_2 component within the range of 0.6 wt% as an additive, BaTi whose powder particle size is within the range of 0.3 to 2.0 μm.
O_3 component powder 94.74-99.55 mol%, Nb_
2O_5 component 0.43 to 4.98 mol%, Bi_2O_
It is characterized by adding 0.05 to 0.6 wt% of the MnO_2 component as an additive to the composition consisting of the three components in a range of 0.02 to 0.28 mol%. High dielectric constant porcelain.