JPS5857844B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION La2Ti2o7. The present invention relates to a ternary ceramic dielectric material composed of Sr2Nb2O79MgTiO3.

The present invention provides a porcelain 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 compensation porcelain capacitors are often used as circuit elements in communication equipment and color televisions, etc. In this case, the temperature coefficient is small (for example -350 to +200 ppm/℃), and the temperature coefficient remains constant with respect to temperature. It is hoped that this will happen.

In this 1, as this kind of material, SrTiO3, CaTi
O3゜Mg T i03 t Ca Z r 03'
A composition containing J as a main component is used.

However, these materials have a temperature coefficient of dielectric constant of -350
～+200 pp Town 4c has a dielectric constant value of 30～
16, and furthermore, the temperature dependence of the temperature coefficient, that is, the linearity of the temperature coefficient, was as large as ±60 pprry/″C or more.

As a material to compensate for these drawbacks, La2O3-Ti02-
MgO-based materials were developed (Japanese Patent Application Laid-Open No. 4912400)
.

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.

By synthesizing a ceramic dielectric material composed of La2Ti2O7, Sr2Nb2O79MgTiO3, the temperature coefficient of permittivity is small, the permittivity is high, the dielectric loss is small, and the temperature change in permittivity is almost linear, making it an excellent temperature compensation material. It was discovered that it can be used as a porcelain dielectric material.

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 with reference to Examples.

Example La2O3, TiO2, SrCO3, Nb2055Mg
0 powder according to each composition, mixed in a ball mill, filtered and dried, and heated at 1000°C to 1200°C for 2
Pre-fired on time conditions.

After that, it is pressure-formed into a disc with a diameter of 16 degrees and heated to 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.

The dielectric constant and dielectric loss were measured using a capacitance bridge at a frequency of 1 kHz.

The temperature coefficient is the dielectric constant value - 80℃, 0℃, and 20℃.

Measurements were made at each temperature of 55°C and 85°C, and the value of the dielectric constant at 20°C was used as a reference.

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

However, TK: Temperature coefficient (ppm/c)ε Dielectric constant value at T, T℃ 20. Dielectric constant value towards 20″cK T: Measurement temperature Representative examples of the results obtained are listed in the table.

Each component composition ratio in the table is indicated by a black circle in the figure, and numbers are also given in the figure to correspond to the numbers of Examples.

The reason why the temperature coefficient column in the table is indicated by 2 indicates that the temperature coefficient at each temperature from 30° C. to +85° C.1 is within the range of 200° 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, in practice, the temperature coefficient, which is the most important characteristic, can be changed from about +40 ppm/"c to - by adjusting the composition ratio.
It can be seen that it can be changed freely at about 350 ppm/℃.

Moreover, the change in temperature coefficient with respect to temperature is ±30 p.
It is very small, less than pm/'c, that is, the change in dielectric constant with temperature is linear.

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

31 and 32 in the porcelain dielectric material composed of La2Ti2q, Sr2Nb2O79MgTiO3.

*33.34.6, Within the composition range surrounded by A, the temperature coefficient changes with respect to temperature by more than ±30 ppm.

Further, within the composition range surrounded by 39, 40, 41 in the table and the composition of MgTiO3, ie, 39, 40, 41°B in the figure, the dielectric constant value is smaller than 30.

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

In the ternary system of La2Ti2O7, Sr2079MgTiO3, XCLa2Ti2O7〕・YC8r2Nb207〕・Z
(MgTiO3) (X+Y+Z= 1.00)
When the values of x, y, and z are expressed as 45 0.20 0.45 0.35 0.30 0.50 0.20 0.25 0.65 0.1 0.15 0.85 0 (excluding composition ranges in which the value of is zero, composition ranges in which the value of Y is zero, and composition ranges in which the value of Z is zero).

[Brief explanation of drawings]

The figure shows the composition range of the composition of the present invention and the composition ratio of the composition shown in the Examples. In the figure, A represents 5r2Nb207, and B is Mg
It represents T s 03 .

Claims (1)

[Claims] I La2Ti2Q, 5r2Nb2(), tMgTi
In the 03o three-way system, XCLa2Ti2O7〕・YC8r2Nb2oT〕・Z
When expressed as [Mg T io 3 ] (however, LX+Y+Z= 1.00), X,
Y. A composition range surrounded by composition ratios having different values of Z (however, a composition range where the value of X is zero, a composition range where the value of Y is zero, and a composition range where the value of Z is zero) A porcelain dielectric material for temperature compensation, characterized in that it has a composition as follows.