JPS593009B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

Detailed Description of the Invention The present invention provides sr2Nb_2O_7, sr2Ta_2O_7
, 1M contribution Ti_2_-_2_x04-! This relates to a ceramic dielectric material of the system represented by X (0 x 1.0).

The present invention has a large dielectric constant, low dielectric loss, and can freely change the temperature coefficient of the dielectric constant over a wide range.
Furthermore, the present invention provides a temperature-compensating ceramic dielectric material whose temperature coefficient does not change over a wide temperature range. 5 Temperature-compensating porcelain capacitors are often used as circuit elements in communication equipment, color televisions, etc. In this case, they have a large dielectric constant,
It is always desired that the dielectric loss be small, and it is desired that the temperature coefficient be any specified value, and that it should remain constant with respect to temperature.

Until now, materials of this type include SrTiO3, CaT
Compositions containing i03, MgTiO3, CaZrO3, etc. as main components have been used, but these materials have a small temperature coefficient of dielectric constant, with a dielectric constant value of 3015 to 1.
6, and furthermore, the temperature dependence of the temperature coefficient, that is, the change in temperature coefficient with respect to temperature, was as large as ±60 pμm/C or more.

In addition, materials with a large temperature coefficient of dielectric constant have the disadvantage that the temperature coefficient varies greatly with temperature. F0
Therefore, La_2 is one of the materials that can compensate for these drawbacks.
03-TiO2-MgO based materials have been developed (Japanese Patent Application Laid-Open No. 12400/1983). In this system, we have succeeded in reducing the temperature coefficient to almost zero, and the temperature dependence of the temperature coefficient has also been improved to some extent. However, it was impossible to adjust the temperature coefficient depending on the purpose. The present invention improves these drawbacks.

That is, sr2Nb_2O_7, sr2Ta_2O_
7. By synthesizing porcelain dielectric materials of the system represented by 1. We have discovered that this material is an excellent temperature-compensating porcelain dielectric material that can be freely changed and has a constant temperature coefficient of permittivity over a wide temperature range. Furthermore, it has been found that the firing temperature is relatively low and the composition is easy to manufacture. below,
The effectiveness of the present invention will be explained based on Examples.

For the porcelain dielectric material composed of the example (0<x 1.0), SrCO3, Nb2O, Ta2O5, TiO2, M
gO powder, Sr2Nb2O7, sr2Ta2
O7, -Mg2XTi2-! For porcelain dielectric materials composed of XO4l (X=0), SrCO3, Nb2O
5. Ta2O,, TlO2 powder and Sr2N 0
7,sr2Ta2~,t! Equation 12,0490 (X=1.
0) for the porcelain dielectric material composed of SrCO3,
Nb2O5, Ta2O5, MgO powders were weighed according to each composition, mixed in a ball mill, filtered, dried,
Prebaking was performed at 1000°C to 1200°C for 2 hours.

After that, it was pressure-formed into a disc with a diameter of 16u and heated to 1300℃/
Firing was performed at 1450° C. for 1 to 2 hours. After baking silver electrodes on both sides of the obtained porcelain at 600°C, dielectric properties were measured under the following conditions. Dielectric constant and dielectric loss are 1KH
Measurements were made using a capacitance bridge at a frequency of z. The temperature coefficient is the dielectric constant value -30℃, O℃, 20℃, 5
It was measured at each temperature of 5°C and 85°C, and the dielectric constant value at 20°C was used as a reference. Here, the temperature coefficient was calculated according to the following formula.

Among the results obtained, representative examples are listed in Table 1. In addition, the display of 2 in the column of temperature coefficient in Table 1 indicates that the temperature coefficient at each temperature from -30°C to 85°C is within the range of 2.

As is clear from Table 1, Sr2Nb2O,, Sr2T
a2O7, -2V1g2XTi2-XO4S! X(0≦
The magneto-dielectric material composed of x x 1.0) has a high dielectric constant and exhibits excellent characteristics such as low dielectric loss. By further adjusting the composition ratio, the temperature coefficient value can be adjusted to approximately +
It is clear that it can be adjusted in a very wide range from about 60 Ppm/C to -1100 ppm/C. Furthermore, the change in temperature coefficient with respect to temperature is within ±30 ppm/C or within ±10% of the temperature coefficient. On the other hand, Sr.
In a composition range in which 2Ta2O7 is more than 60 mol %, dense sintering is not achieved even when firing is performed at 1450°C.

Therefore, this composition range is inappropriate as a practical material. Also, a composition range in which Sr2Nb2O7 is more than 65 mol%, and Ashi. Ti24A, (0 x x 1.0) is 2
In a composition range less than 0 mol %, the condition that the change in temperature coefficient with respect to temperature is within ±30 ppm//C or within ±10% of the temperature coefficient is not satisfied. Also Sr2Nb
A composition range in which 2O7 is less than 5 moles (!) 1 and!
2XTi21X(0<.x≦1.0) is 80 mol%
Over a larger composition range, the change in temperature coefficient with temperature is ±
The conditions of 30 ppm/° C. or within ±10% of the temperature coefficient and the condition that the dielectric constant value is 30 or more are not satisfied at the same time. Based on the above, the composition range of the present invention is limited to the following composition range.

Claims (1)

[Claims] 1 Sr_2Nb_2O_7, Sr_2Ta_2O_7
, 1/2Mg_2_xTi_2_-_2_xO_4_-
In the three-component system of _2_x (0<x≦1.0), α[
Sr_2Nb_2O_7]・β[Sr_2Ta_2O_
7]・γ[-Mg_2_xTi_2_-_2_xO_4
____2_x] (however, α+β+γ=1.0), the values of α, β, and γ are each 0.05≦α≦
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the following conditions: 0.65, 0<β≦0.6, 0.2≦γ≦0.8.