JPS593010B2 - Porcelain dielectric material for temperature compensation - Google Patents

Description

Detailed Description of the Invention The present invention provides La_2Ti_2O_7, Sr2Ta_2O_
7, →kg2XTi_2-J2X04-! X (but 0
, for the system expressed as X≦1.0).

It relates to porcelain dielectric materials. The present invention provides a porcelain dielectric material for temperature compensation, which has a large dielectric constant, a small dielectric loss, and can freely change the temperature coefficient of the dielectric constant over a wide range, and whose temperature coefficient does not change over a wide temperature range. This is what we provide.

5 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 and the dielectric loss be small, and the temperature coefficient can be set to any specified value. It is also desired to maintain a constant value with respect to temperature.

10 Until now, materials of this type include SrTiO3, C
Compositions containing aTi03, MgTiO3, CaZrO3, etc. as main components have been used, but these materials have a small temperature coefficient of dielectric constant, with 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 more than ±60 pμm/C, which was a large drawback.

In addition, materials with a large temperature coefficient of dielectric constant have the disadvantage that the temperature coefficient varies greatly with temperature. So, as one of the materials to compensate for these shortcomings! 0La_2
03-TiO2+MgO based material was developed (Japanese Patent Application Laid-Open No. 12400/1983). In this system, we have succeeded in reducing the temperature coefficient to almost zero, and the temperature dependence of the temperature coefficient has also been improved to some extent. However, it was impossible to adjust the temperature coefficient according to the purpose. The present invention improves these drawbacks.

That is, La_2Ti_2O_7, Sr2Ta_2O
＿7 "Mg2XTi_2→X04-2X (However, 0kuX
By synthesizing magnetic dielectric materials of the type <1.0), 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 range. We have discovered that this material can be an excellent temperature-compensating porcelain and electrical material that has a constant temperature coefficient of dielectric constant over a wide temperature range. 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.
For the porcelain dielectric material composed of the example (0×1.0), La2O3, TlO2, SrCO3, Ta2O5, M
The powder of gO is also converted into La2Tl2O7, Sr2Ta2O7
, La2O3, TlO2, Sr
Weigh the powders of CO3 and Ta2O5 according to each composition, mix them in a Pall mill, filter and dry them to a powder of 1000 to 1
Prebaking was performed at 200°C for 2 hours.

After that, it is pressure-formed into a disk with a diameter of 16 mm 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. Dielectric constant and dielectric loss are 1K
Measurements were made using a capacitance bridge at a frequency of Hz. The temperature coefficient is the dielectric constant value -30℃, 0℃, 20℃,
It was measured at each temperature of 55°C and 85°C, and the dielectric constant value at 20°C was determined. 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 -30° C. to 85° C. is within the range of 20° C.

As is clear from Table 1, the porcelain dielectric material composed of La2Tl2O7 has a large dielectric constant and a small dielectric loss.
It shows excellent properties.

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 approximately +100 ppm/C to approximately -1100 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 a composition range in which Sr2Ta2O7 is more than 60 mol %, dense sintering is not achieved even if firing is performed at 1450°C.

Therefore, this composition range is not suitable for practical materials. Also,
A composition range in which La2Ti2O7 is less than 10 mol%, and -2. Mg2XTi2-! XO4-! 0 (0ku≦1
．． 0) is more than 80 mol%, the condition 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.

In the three-component system (O x x 1.0), when expressed as (α+β+r=1.0), α, β,
The value of γ is 0.1≦α 1, 0, 0<β 0.
60,0〈r＜. A porcelain dielectric material for temperature compensation, characterized in that it has a composition made within a range that satisfies the condition of 0.8.

Claims (1)

[Claims] 1 La_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[L
a_2Ti_2O_7]・β[Sr_2Ta_2O_7
]・γ[1/2Mg_2_xTi_2_-_2_xO_
4_−_2_x] (however, α+β+γ=1), the values of α, β, and γ are respectively 0.1≦α≦1.0,
A porcelain dielectric material for temperature compensation, characterized in that it has a composition that satisfies the conditions of 0<β≦0.60 and 0<γ≦0.8.