JPS597167B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-component ceramic dielectric material of La2Ti2O7 and Ca2Nb207.

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.
We provide a temperature-compensating porcelain dielectric material whose temperature coefficient value does not change over a wide temperature range.Temperature-compensating porcelain capacitors are often used as circuit elements in communication equipment, color televisions, etc. It is always desired that the dielectric constant be large and the dielectric loss be small, and that the temperature coefficient be any specified value and be kept constant with respect to temperature.

Until now, this relative material has been SrTiO3, CaT
Compositions containing iO3, MgTiO3, CaZrO3, etc. as main components have been used, but these materials have a small temperature coefficient of dielectric constant of 30 to 16, and the temperature dependence of the temperature coefficient is small. The change in temperature coefficient with respect to temperature was also large, as it was +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. Therefore, La203-T is one of the materials that compensates for these drawbacks.
iO2-MgO-based materials were developed (Japanese Patent Application Laid-Open No. 1983-1983)
2400). 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 has been impossible to adjust the temperature coefficient depending on the purpose. The present invention improves these drawbacks.

In other words, by synthesizing the ceramic dielectric materials of the La2Ti207 and Ca2Nb207 systems, the dielectric constant is large and the dielectric loss is small.Moreover, the temperature coefficient of the dielectric constant can be freely changed over a wide range, and the dielectric constant can be changed over a wide temperature range. It has been discovered that this material can be an excellent temperature-compensating porcelain dielectric material with a constant temperature coefficient value. Furthermore, it has been found that the firing temperature is relatively low and the composition is easy to manufacture. The effectiveness of the present invention will be explained below based on Examples.

Example Powders of La203, TiO2, CaCO3, and Nb2O5 were weighed according to their respective compositions, mixed in a ball mill, filtered, dried, and prefired at 1000°C to 1200°C for 2 hours.

After that, it was pressure-formed into a disc with a diameter of 161 mm and a diameter of 1300~1
Firing was performed at 450° 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
Measured using a capacitance bridge at a frequency of 7
Ta. The temperature coefficient is the dielectric constant value -30℃, 0℃, 20℃,
It was measured at each temperature of 55°C and 55°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. Representative examples of the results obtained are listed in Table 1. Furthermore, the + symbol in the temperature coefficient column of Table 1 indicates that the temperature coefficient at each temperature from -30°C to 85°C is within the range of +.

As is clear from Table 1, La2Ti2O7,Ca2-
A porcelain dielectric material composed of Nb2O7 exhibits excellent properties such as a large dielectric constant and 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 280 ppm7/C to +92 pprv/C. Moreover, the change 3 in the temperature coefficient with respect to temperature is within ±30 pp, i.e., τ, or within 10% of the temperature coefficient. on the other hand,
In the composition range where La2Ti2O7 is less than 5 mol% and in the composition range where Ca2Nb2O7 is 95 mol% or more, the change in temperature coefficient with respect to temperature is 30 pprrv/V. The condition that the temperature coefficient is 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.

Temperature compensation characterized by having a composition made in a binary system of La2Ti2O7, Ca2Nb2O, where the value of d satisfies the condition O<d<0.95 when expressed as (1-d)La2Ti2O7.DCa2Nb2O7. Porcelain dielectric material for use.

Claims (1)

[Claims] 1 La_2Ti_2O_7, Ca_2Nb_2O_7
In the binary system of (1-α)La_2Ti_2O_7
・When expressed as αCa_2Nb_2O_7, the value of d is 0
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the condition <α<0.95.