JPS5851363B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic dielectric material of the type La2Ti2O7, Nd2Ti207.

The present invention has a large dielectric constant, a small dielectric loss, and the temperature coefficient of the dielectric constant can be freely changed over a wide positive range to a wide range, and the value of the temperature coefficient does not change over a wide temperature range. A compensating porcelain dielectric material is provided.

Temperature-compensating porcelain capacitors are often used as circuit elements in communication equipment, color televisions, etc. In this case, it is always desired that the dielectric constant be large and the dielectric loss be small L, and the temperature coefficient can be set to any specified value. It is desired to maintain a constant value with respect to temperature.

Until now, 5rTi02 has been used as this type of material.

Compositions containing CaTiO2, MgTiO3, CaZrO3, etc. as main components have been used (・However, these materials have a small temperature coefficient of dielectric constant, and the dielectric constant value is 30.
The temperature coefficient is as small as ~16, and the temperature dependence of the temperature coefficient, that is, the change in the temperature coefficient with respect to temperature, is ±60 pp.
m/℃ or higher, there was a slight defect.

Further, in the case of a material having a large temperature coefficient of dielectric constant L, there is a drawback that the temperature coefficient changes greatly with respect to temperature.

In particular, in the past, porcelain dielectric materials with positive temperature coefficients had a limited range of temperature coefficients.

Therefore, La2O3 is one of the materials that compensates for these drawbacks.
-T i02 - MgO-based materials have been developed (Japanese Patent Application Laid-open No. 12400/1983).

In this system, we succeeded in reducing the temperature coefficient to almost zero,
Moreover, 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 ceramic dielectric materials of the La2Ti2O7 and Nd2Ti207 systems, the dielectric constant is large, the dielectric loss is small, and the temperature coefficient of the dielectric constant can be freely changed over a wide positive range, and it can be used over a wide range. It has been discovered that this material can be an excellent temperature-compensating porcelain dielectric material whose temperature coefficient of permittivity is constant in the temperature range of .

Furthermore, the firing temperature was relatively low and the composition was found to be easy to manufacture.

Hereinafter, the present invention will be described in detail based on examples.

Example A porcelain dielectric material composed of La2Ti2O7 and Nd2Ti207 was prepared by weighing powders of La2O3, TiO2, and Nd2O3 according to their respective compositions, mixing them in a ball mill, filtering, drying, and heating at 1000°C to 1200°C for 2 hours. I prefired it.

After that, it is pressure-formed into a disk with a diameter of 16 m 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.

The dielectric constant and dielectric loss were measured using a capacitance bridge at a frequency of lKH2.

The temperature coefficient is the dielectric constant value - 30°C. 0℃, 20℃, 55
It was measured at each temperature of .degree. C. and 85.degree. C., and the dielectric constant value at 20.degree. C. was used as a reference.

◆☆The temperature coefficient was calculated according to the following formula.

TKE= ''' ε2o (T-20) However, TKε: Temperature coefficient (ppm/'C) ε: T℃
Dielectric constant value ε2o at 20°C: Dielectric constant value T at 20°C: Measurement temperature Typical examples of the obtained results are listed in Table 1.
Ta.

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, La2Ti2O7.

The porcelain dielectric material composed of Nd2Ti207 has a high dielectric constant and low dielectric loss, and exhibits excellent characteristics such as L.
Ru.

It is clear that by further adjusting the composition ratio, the temperature coefficient f can be adjusted over a very wide positive range of approximately +60 pprIN/°C to +260 ppm/°C.

Moreover, the change in temperature coefficient with respect to temperature is ±30 pp%/
It should be within 'C or within 1o of the temperature coefficient.
Ru.

On the other hand, in the composition range where Nd2T i 207 is more than 95 moles, the temperature coefficient changes with temperature by ±30 ppm7.
L・ that is within ℃ satisfies the condition of being within +10 of the temperature coefficient.

Based on the above, the composition range of the present invention is limited to the following composition range.

In the binary system of La2Ti2O7 and Nd2Ti207 (
・Te, (1-α)La2Ti207 ・αNd2Ti2
A porcelain dielectric material for temperature compensation, characterized in that it has a composition in which the value of α, expressed as 0.07, satisfies the condition O<α≦0.95.

Claims (1)

[Claims] 'I In the binary system of La2Ti2O7, Nd2Ti207 (1-a) La2Ti207 @ αNd2
A porcelain dielectric material for temperature compensation, characterized in that it has a composition in which the value of α, when expressed as Ti207, satisfies the condition of 0<α≦0.95.