JPS593005B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on Nd2Ti2O_7, sr2Ta_2o7, -Mg2XTi2-2X04-2X (with 0<X<1.
The present invention relates to a ceramic dielectric material of the type represented by 0).

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.
The present invention also provides a temperature-compensating porcelain dielectric material whose temperature coefficient does not change over a wide temperature range.

Temperature-compensating ceramic capacitors are often used as circuit elements in communication equipment, color televisions, etc. In this case, it is always desirable to have a high dielectric constant and low dielectric loss, and the temperature coefficient can be set to any specified value. , 10 and is desired to maintain a constant value with respect to temperature.

Until now, materials of this type include SrTiO3, CaT
Compositions containing iO3, MgTiO3, CaZrO3, etc. as main components have been used, but these materials have a dielectric constant value of 30 to 16 if the temperature coefficient is small.
Furthermore, 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.

Further, those having a large temperature coefficient of dielectric constant have a drawback that the temperature coefficient changes greatly with respect to temperature by 20 degrees. Therefore, La_2O 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, the temperature coefficient was successfully reduced to almost zero, and the temperature dependence of the temperature coefficient 25 number was also improved to some extent. However, it has been impossible to adjust the temperature coefficient depending on the purpose. The present invention improves these drawbacks.

That is, Nd2Ti2O7, Si2Ta_202, 1M
g2XTi2-2X04-2X (Tap 0<X 1.0
) By synthesizing the ceramic dielectric material of the system shown in 35, it has a large dielectric constant and low dielectric loss, and the temperature coefficient of the dielectric constant can be freely changed over a wide range35, and the dielectric constant can be maintained 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 Nd2Ti2α, Sr2Ta2O,, -Mg2XTl2-2X04-2X (0x1.0)
For porcelain dielectric materials composed of Nd2O2, Ti
Powders of O2, SrCO2, Ta2O5MgO, and N
d2Ti2O7sr2Ta2O7 La-Mg2XTi2.
Regarding the ceramic dielectric material composed of 2XO←2x(X3O), Nd2O2, TlO2, srcO2, Ta2O
Weigh the powders of No. 5 according to each composition, mix them using a ball mill, filter and dry them at 10,000C to 1,200C,
Prebaking was performed for 2 hours.

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. Are permittivity and dielectric loss an illusion? Measurements were made using a capacitance bridge at the frequency of . The temperature coefficient is the dielectric constant value -30℃, O℃, 20℃,
The dielectric constant was measured at each temperature of 55° C. and 85° 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. In addition, the display of 2 in the column of temperature coefficient in Table 1 indicates that the temperature coefficient at each temperature from -300C to 85C is within the range of 2.

As is clear from Table 1, Nd2Ti2O7,sr2T
a2O7P-Mg2XTi2yo2X (0kuXku1●0)
The porcelain dielectric material composed of has a high dielectric constant and low dielectric loss. By further adjusting the composition ratio, the temperature coefficient value can be adjusted to approximately +240 ppm/
It is clear that it can be adjusted in a very wide range from .degree. C. to about -1500 ppm/.degree. Moreover, the change in temperature coefficient with respect to temperature is within ±30 ppm/℃ or ± of the temperature coefficient.
It is within 10%. On the other hand, Sr2Ta2O7
In a composition range where the amount is more than 55 mol %, dense sintering will not occur even when fired at 1450°C.

Therefore, this composition range is not suitable for practical materials. Also N
A composition range in which d2Ti2O7 is less than 5 mol%, and -Mg2XTl2-2X04-2X (0〈X〈1.0)
In a composition range in which is more than 80 mol %, the conditions that the change in temperature coefficient with respect to temperature is within ±30 ppm/° C. or 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. Nd2Tl2O7,
Sr2Ta2O7, -Mg2XTl2-2X04-2X (0<.x<1.0
) in the three-component system α[Nd2Tl2O7]・β[S
r2Ta2O7]・γ[-Mg2XTi2-2X04-
2X] (Tax α + β + γ - 1.0), α
, β, and γ satisfy the following conditions, respectively: 0.5 × α<1.0, 0<β × 0.55, 0<γ<0.8. Porcelain dielectric material for compensation.

Claims (1)

[Claims] 1 Nd_2Ti_2O_7, Sr_2Ta_2O_7
, 1/2Mg_2_xTi_2_-_2_xO_4-_
In the three-component system of 2_x (0≦x≦1.0), α[Nd
_2Ti_2O_7]・β[Sr_2Ta_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 each 0.05≦α<1.0,
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the conditions of 0<β≦0.55 and 0<γ≦0.8.