JPS593007B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides sr2Ta2o7, Ca2Nb2O_7, 1M
The present invention relates to a ceramic dielectric material of the system expressed as g_2_xTi2-_2_xO_4-_2_x (T=0<X<1.0).

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

Temperature-compensating ceramic 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 < 0, and the dielectric loss be small 0, and the temperature coefficient can be set to any specified value. It is desirable to maintain a constant value with respect to temperature.

Until now, materials of this type include SrTiO3, CaT
15 with main components such as i03, MgTiO3, CaZrO3, etc.
However, in these materials, those with a small temperature coefficient of dielectric constant have a dielectric constant value of 30 to 16.
Moreover, the temperature dependence of the temperature coefficient, that is, the change in the temperature coefficient with respect to temperature, was as large as ±60 pμm/°C or more.

In addition, those with a large temperature coefficient of dielectric flux had the disadvantage that the temperature coefficient varied greatly with temperature.
Therefore, La20 is one of the materials that compensates for these drawbacks.
3-TiO2-MgO based materials were developed (Japanese Unexamined Patent Publication No.
9-12400). In this system, we have succeeded in reducing the temperature coefficient 5 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.

30 i.e. sr2Ta2o7, Ca2Nb2O_7
, -Mg_2_xTi2-_2_xO_4-_2_x(
By synthesizing ceramic dielectric materials of the system shown by 0<x<1.0), the dielectric constant is large and the dielectric loss is small.
Moreover, 9U is an excellent temperature-insulating porcelain dielectric material whose temperature coefficient of dielectric constant can be freely changed over a wide range and whose temperature coefficient is constant over a wide temperature range. This is what I discovered.

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.

Regarding the porcelain dielectric materials constructed in the examples, SrcO3, Ta2O3,
Powders of CaCO3, Nb2O5, MgO, TiO2,
For porcelain dielectric materials composed of Sr2Ta2O7 and Ca2Nb2O7, the powder was weighed according to each composition, mixed in a ball mill, filtered, dried, and preheated at 1000°C to 1200°C for 2 hours. Baked.

After that, it was pressure-formed into a disc with a diameter of 16 wrm, and
Firing was carried out at a temperature of 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 1 KHz. The temperature coefficient is the dielectric constant value -30℃, 0℃,
Measured at each temperature of 20℃, 55℃, 85℃, 20℃
It was determined based on the dielectric constant value at . 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, the porcelain dielectric material composed of has a high dielectric constant and exhibits excellent characteristics of low dielectric loss.

It is clear that by further adjusting the composition ratio, the value of the temperature coefficient can be adjusted over a very wide range from about +240 ppm/°C to about -940 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, in the composition range where Sr2Ta2O7 is more than 65 mol%, the temperature coefficient changes with temperature by ±30 ppm/℃.
The condition of being within ±10% of the temperature coefficient is not satisfied.

In addition, in the composition range where Ca2Nb2O7 is less than 15 mol% and the composition range where it is more than 1%, the temperature coefficient changes with temperature within ±30 ppm/°C or ±1 of the temperature coefficient.
The condition that the dielectric constant is within 0% 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.

-Mg2XTl2-2X04-2X (0<.x 1.0
) in the three-component system α[Sr2Ta2O7]・β[C
a2Nb2O7]・γ[-Mg2XTi2-2X04-
2X] (however, α+β+γ=1.0), α
, β, and γ are 0.65 and 0.15, respectively.
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the following conditions: β × 1.0, 0 × γ × 0.85.

Claims (1)

[Claims] 1 Sr_2Ta_2O_7, Ca_2Nb_2O_7
, 1/2Mg_2_xTi_2-_2_xO_4-_2
In the three-component system of _x (0<x<1.0) α[Sr_
2Ta_2O_7]・β[Ca_2Nb_2O_7]・
γ[1/2Mg_2_xTi_2-_2_xO_4-_
2_x] (however, α+β+γ=1.0), the values of α, β, and γ are 0<α≦0.65 and 0.15, respectively.
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the following conditions: ≦β<1.0, 0<γ<0.85.