JPS6340214A - Dielectric ceramic composition for microwave - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dielectric ceramic composition for microwave use, and in particular to a microwave filter, an oSC (oscillator) for LNB, a DEBREXER, and a VCO (@oppression 90 oscillator). The present invention relates to a composition suitable for dielectric ceramic materials for microwave circuits such as the above.

[Conventional technology]

Dielectric materials have been widely applied to microwave circuits such as oscillators for satellite broadcast reception.

In recent years, this trend has been accelerated more and more, and the frequency band has expanded from the low frequency region to the sub-millimeter wave region to the millimeter wave region, and higher performance dielectric materials are required. Conventionally, Ba0-TiO□-based dielectric materials have been used as dielectric materials.

(Problems to be solved by the invention) In the B a O-T i Og-based dielectric material, B
The composition ratio of aO and Tie is appropriately selected, or BaO
It is possible to freely control the temperature coefficient of the dielectric material by using appropriate additives for the composition of the dielectric material and Tie. However, in the conventional Ba0-TiO□-based dielectric material as described above, the sintered body tends to be unified, which results in a large loss of dielectric constant, and the linearity of temperature characteristics cannot be sufficiently ensured. It had the following problems.

The purpose of the present invention is to solve the problems of the prior art described above,
It is an object of the present invention to provide a dielectric ceramic composition for microwave use, which has a high dielectric constant, a small dielectric loss, a small temperature coefficient of the dielectric constant, and a constant temperature coefficient within a predetermined temperature range.

[Means for solving problems]

For the above purpose, BaO (18-22 mol%), -Tilt (78-22 mol%)
82 mol%), Hbto
, (0.5-3.5 wt%) and WOl (0.1-3.0
% by weight),
and BaO (18-22 mol%), Tic)z (78
~82 mol%), Nb,
Os (0.5-3.5% by weight) and WOl (0.1-3.5% by weight)
This is achieved by a dielectric ceramic composition containing Zn0 (17% by weight or less) and Zn0 (17% by weight or less).

In the microwave dielectric ceramic composition of the present invention, Ba
0 (18-22 mol%) and Ti0z (78-82 mol%
) is the main component. When BaO and TiO2 are outside the above range, the dielectric loss becomes large in both cases, making it impossible to measure the properties as a dielectric material.

The present invention has the above-mentioned components as main components, and Nbz
It has a composition containing Os and WOl.

The amount of Nbzos added is between 0.5 and 3.5% by weight. The addition of Nb, o, increases the temperature coefficient of the dielectric material by +7
The purpose is to maintain the temperature constant within the range of 0°C to -50°C, but if the amount added is less than 0.5% by weight, the effect will be small.
On the other hand, if the amount added exceeds 3.5% by weight, it becomes difficult to keep the temperature coefficient constant and the no-load Q (Qu) further decreases.

The amount of Wo added is 1 to 3.0% by weight of O.

The purpose of adding WOl is to reduce the dielectric loss of the dielectric material, and if the amount added is less than 0.1% by weight, the effect of reducing dielectric loss will be low;
On the contrary, dielectric loss increases when the value exceeds .

In the present invention, in the case of a dielectric ceramic composition containing ZnO, ZnO changes the temperature coefficient (τ, .) of the dielectric material from positive to negative while maintaining the dielectric constant (εr) at 30 or more. be able to. In this case, if the amount of ZnO added exceeds 17% by weight, the temperature coefficient (τ, .) becomes too large on the negative side and the dielectric constant (εr) further decreases.

[Embodiments of the invention]

Raw materials BaCO5, Tie, ZnO1NbtO, and WOz were weighed to have the compositions shown in Table 1, wet mixed, filtered and dried, and calcined at a temperature of 1000°C. After crushing, granulating and molding this calcined product, 1200 ~
A sample fired in the air at a temperature of 1350° C. for 10 hours was measured at a frequency of about 13 GH. The results are shown in Table 1.

Although BaC0+ was used instead of BaO as a raw material, carbonates such as Ba COs are chemically more stable than oxides such as BaO, and in the calcination process,
Since B a CO3 is decomposed into BaO and CO□, it does not affect the properties of the dielectric material.

Further, FIG. 1 shows the relationship between the amount of NbzOs added and the temperature characteristics of the dielectric material in Examples 4, 11, and 12 shown in Table 1.

From Table 1, Examples 1 to 14 all have a dielectric constant (ε
While keeping r) high, the no-load Q (Qu) is set to 300.
0 or more, and the temperature coefficient is τ. This shows that you can freely control it.

Also, from Figure 1, the amount of NbzOs added is 2.5% by weight.
When the temperature/frequency change is most linear, the amount of NbzOs added is 0. At 5% by weight, the effect of linearizing temperature/frequency changes is slightly lower than at 2.5% by weight.
Furthermore, when the amount of Nb, O, added is 3.5% by weight, the linearity of temperature/frequency change increases considerably, and therefore Nb2O
It is recognized that when the amount of 2 added exceeds 3.5% by weight, the temperature characteristics deteriorate.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to sufficiently ensure linearity of temperature characteristics while maintaining a high dielectric constant and a low dielectric loss.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the amount of NbzOs added and the temperature characteristics of the dielectric material.

Claims (2)

[Claims] (1) BaO (18-22 mol%), TiO_2 (78
~82 mol%), Nb_
2O_3 (0.5-3.5% by weight) and WO_3 (0.1
3.0% by weight). (2) BaO (18-22 mol%), TiO_2 (78
~82 mol%), Nb_
2O_3 (0.5-3.5% by weight) and WO_3 (0.1
3.0% by weight) and ZnO (17% by weight or less).