JPH069124B2 - 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 ceramics are applied to impedance matching of dielectric resonators, microwave integrated circuit boards, and various microwave circuits in the microwave frequency range. Especially recently, filters and guns or F
A large number of ET 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 applicable to the microwave region, a dielectric constant that can be put to practical use, and stable temperature characteristics. .

The present invention <Means for Solving the Problems> is 15 to 25 mol% of BaO, the composition comprising the allocation of the TiO ₂ 75-85 mol%, Ba a _{(Ni1 / 3Ta2 / 3) O} 3 0 Less than 0.2% by weight, a total amount of 0.1 to 1.2% by weight of one or two or more kinds of metal oxides of the group consisting of La ₂ O ₃ , Fe ₂ O ₃ , and Ta ₂ O ₅ , and MnO ₂ of 0. It is a dielectric ceramic composition for high frequencies which is added in an amount of less than 0.5% 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, and this is subjected to dry primary pulverization and mixing with a mixer, and then in the atmosphere at a temperature of 1000 ° C. for 6 hours. Calcine. Further, La ₂ O ₃ , Fe was added to the calcined product.
₁ or 2 or more of the metal oxides of the group consisting of ₂ O ₃ and Ta ₂ O ₅ are added, dry primary pulverization and mixing are again performed with a mixer, and then the mixture is mixed in the atmosphere at a temperature of 1000 ° C. for 6 hours.
Calcination for an hour. Further, La ₂ O ₃ , Fe _{2 is} added to the calcined product.
After adding one or more of the metal oxides of the group consisting of O ₃ and Ta ₂ O ₅ and again subjecting them to secondary pulverization and mixing by a dry method with a mixer, they are 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 disk of 15 mmφφ × 10 mmt with a pressing pressure of 00 Kg / cm ² . Next, this shaped body is placed in the atmosphere at 1300 ° C to 14 ° C.
Bake at a temperature of 20 ° C. for 10 hours. Finally 9mmφ × 5mm
It is polished into a disk shape of t, and silver electrodes are baked on the front and back surfaces to make dielectric samples, each with a Q value (= 1 / tan
δ), dielectric constant ε, and resonance frequency temperature coefficient τf are measured.

- For samples added test value La ₂ O _3, results obtained by examining the properties were as shown in the first table corresponding to the blending 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]-[alpha] where [tau]; temperature change rate of permittivity [alpha]; linear expansion coefficient of porcelain sample Also, 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.

The results of adding Fe ₂ O ₃ and Ta ₂ O ₅ instead of La ₂ O ₃ are shown in Tables 2 and 3, respectively.

-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.

<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 by samples 3,6,9,12,15, Q is 3,000 decreases rapidly. (B) La ₂ O ₃ , Fe ₂ O ₃ , and Ta ₂ O ₅ are added to the samples 13, 14, 15, 32, and
Ba as 52 (Ni1 / 3Ta2 / 3) improvement in Q value due to synergy with _{O 3} is not expected.

Further, since the action of each metal oxide is equal, even when two or more kinds thereof are added, the improvement of the Q value cannot be expected when the total amount exceeds 1.2% by weight. C) When BaO is less than 15 mol%, the Q value is low, and τf takes a large positive value like Sample 19. D) When the content of BaO exceeds 25 mol%, the Q value remarkably decreases as in Sample 17.

Therefore, the above range is excluded from the scope of the present invention. E) MnO ₂ is added in a small amount to improve the sinterability, and does not directly improve the Q value.
However, the addition amount becomes excessive at 0.5% by weight or more, and the Q value becomes 3000 or less as in the case of sample 22, so that the addition amount is limited.

<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 resonance frequency temperature coefficient 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
A composition consisting allocation mol%, Ba (Ni1 / 3Ta2 / 3) O 3 less than 0.2 wt%, one of _{La 2 O 3, Fe 2 O} 3, Ta 2 O 5 group metal oxides consisting of or A dielectric ceramic composition for high frequencies, comprising two or more kinds added in a total amount of 0.1 to 1.2% by weight and further containing less than 0.5% by weight of MnO ₂ .