JPH0610928B2 - High frequency dielectric ceramic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is applied in the micro frequency range, exhibits a high Q value in this range, and has a dielectric constant that can be put to practical use and stable. The present invention relates to a dielectric ceramic composition having temperature characteristics.

<Prior Art> With the development of communication networks in recent years, the frequency range used has expanded to reach microwaves. In connection with this, the dielectric porcelain is applied to the dielectric resonator, the micro integrated circuit board, impedance matching of various microwave circuits, etc. in the micro frequency range. Especially recently, filters, guns or FEs
A large number of T microwave oscillators are required for frequency stabilization, and the demand for them is increasing.

However, the dielectric loss tends to increase as the frequency used increases. So in the micro frequency range,
A dielectric porcelain having a large Q value is desired.

<Problems to be Solved by the Invention> Zr is a conventional general high-frequency dielectric ceramic material.
There are O ₂ —SnO ₂ —TiO ₂ system porcelain, BaO—TiO ₂ system porcelain, and porcelain in which a part thereof is replaced with other elements.

However, these materials have various problems such as a small Q value, a small relative dielectric constant, and a failure to obtain a desired temperature coefficient.

It is an object of the present invention to provide a high frequency dielectric ceramic composition having a high Q value adapted to the microwave region, a dielectric constant that can be put to practical use, and stable temperature characteristics. is there.

<Means for Solving Problems> In the present invention, a composition comprising BaO in an amount of 15 to 25 mol% and TiO _{2 in an amount} of 75 to 85 mol% is added to a composition of Ba (Ni1 / 3Ta2 / 3).
O ₃ was added in an amount of less than 0.2% by weight, and MnO ₂ was added in an amount of 0.
A high frequency dielectric ceramic composition containing less than 5% by weight.

<Example> The present invention was carried out as follows.

・ Sample: 99.9% pure BaCO ₃ , TiO ₂ , Ba (Ni1 / 3T
a2 / 3) O ₃ and MnO ₂ are used as starting materials, and a predetermined amount is weighed and mixed according to each composition. The mixture is pulverized and mixed by a dry method with a mixer, and then temporarily stored in the atmosphere at a temperature of 1000 ° C. for 6 hours. Bake. Next, after adding an appropriate amount of organic binder and water to the calcined product and crushing it with an alumina ball of 30 mmφ,
Granulate by spray drying. This granulated raw material 15
It is shaped into a 15 mmφ x 10 mmt disk with a pressing pressure of 00 kg / cm ² . Next, this shaped body is placed in the atmosphere at 1300 ° C to 142 ° C.
Bake at a temperature of 0 ° C. for 10 hours. Finally 9mmφ × 5mmt
It is polished into a disk shape, and silver electrodes are baked on its front and back surfaces,
Dielectric samples, Q value (= 1 / tan δ) for each,
The dielectric constant ε and the resonance frequency temperature coefficient τf are measured.

・ Test value As a result of investigating the characteristics of each sample with a different composition ratio,
The table below shows the corresponding composition.

The values of the dielectric constants ε and Q in the table are measured by the dielectric resonator method. The resonance frequency temperature coefficient τf is −
It was determined from the value in the temperature range of 30 ° C to + 80 ° C based on the following formula.

[tau] f = -1 / 2 [tau] [ _epsilon]-[ alpha] where [tau] [ _epsilon] ; temperature change rate of permittivity [alpha]; linear expansion coefficient of porcelain sample and the resonance frequency was 6.9 GHz.

In each of the following tables, sample numbers surrounded by circles are outside the scope of the present invention.

-Results As is clear from the above table, the dielectric ceramic material of the present invention has a high Q value of 4000 or more in the microwave region, and the dielectric constant ε and the resonance frequency temperature coefficient τf can be put to practical use. It was shown to be.

In addition, in the above-mentioned examples, MnO ₂ is added in a small amount for improving the sinterability, and does not directly improve the Q value. However, the amount added is 0.5% by weight.
With the above, the amount becomes excessive, and the Q value becomes 3000 or less as in Sample 6, so that the addition amount is limited.

<Reason for limiting the present invention> Next, the reason for limiting the composition range of the present invention will be described.

If b) Ba (Ni1 / 3Ta2 / 3 ) O 3 is 0.2 wt% or more, as shown in sample 5, and Q is rapidly decreased 30
It will be 00 units.

B) When BaO is less than 15 mol%, the Q value is low and a large positive value is obtained as in Sample 10.

C) When the BaO content exceeds 25 mol%, the Q value remarkably decreases as in Sample 8.

D) As described above, the addition amount of MnO ₂ becomes excessive at 0.5 important% or more, and the Q value becomes 3000 or less as in Sample 6, so the addition amount is limited to less than 0.5 important%.

Therefore, the above range is excluded from the scope of the present invention.

<Effects of the Invention> The dielectric porcelain composition according to the present invention has a high Q value, and the values of the dielectric constant and the temperature coefficient of the resonance frequency can be suitable for practical use, as has been clarified in the experimental examples.

Therefore, the present invention is most suitable as a dielectric ceramic material applied to the micro frequency range.

Claims (1)

[Claims] 1. BaO 15 to 25 mol% and TiO ₂ 75 to 85
In the composition consisting of the mol% distribution, Ba (Ni1 / 3Ta2 /
3) A high frequency dielectric porcelain composition comprising less than 0.2% by weight of O ₃ and less than 0.5% by weight of MnO ₂ .