JPS5835321B2 - Ondohoshiyoyoujikiyudenzairiyou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to L a2T 1207 ・S r2N b20
The present invention relates to a two-component ceramic dielectric material composed of 7.

The present invention provides a ceramic dielectric material for temperature compensation which has a large dielectric constant, a small dielectric loss, a small temperature coefficient of the dielectric constant, and good linearity over a wide temperature range.

Temperature-compensating porcelain capacitors are often used as circuit elements in communication equipment and color televisions, and in this case the temperature coefficient is small (for example -350 to +20 opp, "c").
Moreover, it is desired that the temperature coefficient maintains a constant value with respect to temperature.

Until now, materials of this type include S rT i03,
CaT i03.

Compositions containing MgTiO3, CaZrO3, etc. as main components are used.

However, these materials have a temperature coefficient of dielectric constant of -350
~+200 pHll/'C has a dielectric constant of 3
0 to 16, and the temperature dependence of the temperature coefficient, that is, the linearity of the temperature coefficient, was also large, being more than ±601)1111/'C.

As a material that compensates for these drawbacks, L a 203-T i
o2MgO-based materials were developed (Japanese Patent Application Laid-Open No. 491240
0).

This material has succeeded in reducing the temperature coefficient to almost zero, and the temperature dependence of the temperature coefficient has 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 using a porcelain dielectric material composed of La2T1207 and Sr2Nb207, the temperature coefficient of dielectric constant is small, the dielectric constant is high, the dielectric loss is small, and the change in dielectric constant with temperature is almost linear. It was discovered that this material can be used as a porcelain dielectric material for temperature compensation.

Furthermore, it has been found that the firing temperature is relatively low and the composition is easy to manufacture.

The present invention will be described in detail below based on Examples.

Example: Consisting of La2T 1207, S r2Nb207°
For the porcelain dielectric material used, L a203, T
i 02 , 5rCO3) Nb205 powder was weighed according to each composition, mixed in a ball mill, filtered through a sieve, dried, and pre-fired at 1000° C. to 1200° C. for 2 hours.

After that, it was pressure-formed into a disc with a diameter of 16 mm and heated to 1300°C.
Firing was performed at ~1450° 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 11d(z).

The temperature coefficient is the dielectric constant value - 80℃, 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.

Here, the temperature coefficient was calculated according to the following formula.

Representative examples of the results obtained are listed in the table.

In addition, the symbol indicated in the temperature coefficient column of the table indicates -
This shows that the temperature coefficient at each temperature from 30° C. to +85° C. is within the range of +85° C.

As is clear from the table, the composition of the present invention exhibits excellent dielectric properties with a high dielectric constant and low dielectric loss.

Furthermore, the temperature coefficient, which is one of the most important properties in practice, can be changed from about +11011%/'C to -15% by adjusting the composition ratio.
It can be seen that it can be freely changed up to about 0111111/'C.

Moreover, the change in temperature coefficient with respect to temperature is ±30ppl.
/°C or less, that is, the change in dielectric constant with temperature is linear.

The above characteristics are most desirable as a circuit element for communication equipment.

As can be seen from the table, it is clear that excellent properties can be obtained when the composition of La2Ti2O7 is in the range of 15 moles or more and less than 100 moles.

However, when the composition of L a2 T 120□ is less than 15 molar, the dielectric loss exceeds 10XIO-' and the change in temperature coefficient with respect to temperature also exceeds ±30111 F/'C.

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

That is, L a2 T I 2072 S r2Nb2
In the binary system of 07, (l-α)La2T s 2
07? In the dielectric ceramic composition expressed as αS r2 N b207 , the value of α is in a range that satisfies the condition of 0 and α≦0.85.

Claims (1)

[Claims] In the binary system of I La2Tt207,5r2Nb207 (1-α) L a2T +207 ・α5r
When expressed as 2Nb207, the value of α is O and α≦0.85
A porcelain dielectric material for temperature compensation, characterized by having a composition made within a range that satisfies the following conditions.