JPS6229010A - Dielectric ceramic composition for high frequency - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency dielectric ceramic composition having a high dielectric constant and a high Q value in a high frequency region such as microwaves and millimeter waves.

[Conventional technology]

In high frequency regions such as microwaves and millimeter waves, dielectric ceramics are widely used for dielectric resonators, dielectric substrates for MrC, and the like.

Conventionally, as this type of dielectric porcelain, for example, T i Oz-
ZrOz -5nOz -ZnO-NiO based materials are known (Japanese Patent Publication No. 34526/1983).

However, the Q value of the above material is 25000 at IGHz.
．． The level was 12000 at 4GHz and 7000 at 7GHz. Therefore, for example low frequencies (e.g. 800
Even if an attempt is made to use it as a dielectric resonator in a high-power circuit (MHz), it generates a large amount of heat and becomes unstable in temperature, making it unusable. Furthermore, there are cases where the Q value is so low that it cannot be used as a dielectric resonator near 4 GHz or 10 GHz.

So, Ti1t -ZrOz Snug -ZnO
-NfO yarn material (TazO instead of DZnO or NiO(7)).

High-frequency dielectric ceramic compositions in which the Q value is improved by adding are proposed in JP-A-58-51406 and JP-A-58-217465, respectively. The dielectric ceramic composition in the former is TfOz 2
2~43 N! -%, Zr0゜38~58wt%, Sn
The main component is 0.9 to 26% by weight, and 7% by weight or less of ZnO, Ta, and O.

In the latter case, 10% by weight or less of NiO was added instead of ZnoO in the former.

[Problem that the invention seeks to solve]

In the material disclosed in the above publication, although the Q value is improved, the maximum value is still only about 8000 at 7 GHz. There is also room for further improvement in sinterability.

Therefore, it is an object of the present invention to provide a dielectric ceramic composition for high frequency use that further improves the Q value and sinterability.

[Means for solving problems]

The dielectric ceramic composition for high frequency of this invention is TiO, 22
~43% by weight, Zr0g 38-58% by weight, 5nOt
The main component is 9 to 26% by weight, and 7% by weight of ZnO.
Below, NiO is 10% by weight or less, Sb*Os is 7% by weight.
The following additives are included.

The reason for limiting the composition to the above composition range is as follows.

That is, when Tie is less than 22% by weight, the dielectric constant (ε) decreases, and when it exceeds 43% by weight, the temperature coefficient of dielectric constant (TC) decreases.
becomes too large on the + side.

Further, when ZrO is less than 38% by weight or exceeds 58% by weight, the temperature coefficient (TC) of the dielectric constant becomes too large on the + side. Furthermore, when Snug is less than 9% by weight, the coefficient (To) of the dielectric constant becomes too large on the 1 side and the Q decreases, and when it exceeds 26% by weight, the temperature coefficient of the dielectric constant (To)
TC) becomes too large on the - side.

Next, among the additives, when ZnO exceeds 7% by weight, the dielectric constant and Q decrease, and when NiO exceeds 10% by weight or s b, o exceeds 7% by weight, Q decreases. will no longer be of practical use.

〔Example〕

Hereinafter, this invention will be explained in detail according to examples.

High purity TiOz, ZrO2, SnO2,
Zn0SNips 5bzOs was weighed and mixed for 16 hours to obtain porcelain having the composition ratio shown in Table 1. Next, the mixed raw material obtained by dehydration and drying was heated to 2500
Kg 7cm” pressure, diameter 12mm, thickness 6a+n
It was molded into a + disc. Continue molding in natural atmosphere 13
Porcelain samples were obtained by firing at a temperature of 50-1450°C for 4 hours.

Dielectric constant (at 25℃, 7GHz) for each ceramic sample
ε), Q, and temperature coefficient (TC) of resonance frequency were measured, and the results are shown in Table 1.

Items marked with * in Table 1 are outside the scope of this invention, and all others are within the scope of this invention.

(Left space below) The dielectric constant (ε) and Q values in Table 1 were measured by the dielectric resonance method. Further, TC represents the temperature change rate of the resonance frequency (fo), and the measurement was performed in a temperature range of +25°C to +85°C.

Temperature change rate of resonant frequency (fo) [TC(f.

)] is obtained from the following formula, which is the temperature change rate (TC(ε)) of the dielectric constant (ε) and the coefficient of linear expansion of porcelain due to temperature change (α
).

TC(fo)='ATC(ε)-α In addition, when the crystal grain size and bending strength were measured for sample number 16, the crystal grain size was 5 to 10 μm, and the bending strength was 120 μm.
0 Kg 7 cm2, and by containing 5bzOs, a porcelain with small crystal grain size and high strength is obtained.

Incidentally, since it was impossible to sinter sample number 7.14.23, the electrical characteristics were not measured.

For comparison, sample number 16 according to the present invention and conventional example Tie, -ZrO2-3nOw-ZnO-N
The relationship between Q and frequency for the jO system is shown in the drawing.

In addition, Ti0z -ZrO2-3nO, -ZnO-Nj
The O-based composition consists of the following: Ti0z: 38% by weight
, Zr0z: 48% by weight, 5nOz: 14% by weight
The main components are ZnO: 1.0% by weight, NjO: 0
．． Added 5% by weight.

As is clear from the figure, in the device according to the present invention, the lower the frequency, the greater the effect of improving Q.

〔Effect of the invention〕

As is clear from the examples described above, in this invention, by using the three components of ZnON1O-3bzOs as additives, a product with stable sinterability and high Q was obtained. For example, the Q value of 7 GH2% TC#O was 8700, which was an unprecedentedly large value.

In other words, in the material of this invention, the crystal grains are smaller and more uniform in size than in conventional materials, and the additive system described above makes crystal growth uniform and suppresses the formation of lattice misalignment within the crystal. It has an effect.

Furthermore, with the material of the present invention, the lower the frequency, the greater the effect of improving Q. This is because the lower the frequency, the larger the unit, but the additive system improved the sinterability and even the large unit was sintered uniformly. For example, the Q value of the material of this invention is 38000.
It is 16000 at 4GHz and 8700 at 7GHz, which is higher than the conventional TiO□-ZrOz-3nO mentioned above.
Compared to the Q value of the □-ZnO-NiO-based material, the Q values are increased by 52%, 33%, and 24% at each frequency.

Therefore, according to the present invention, the application can be expanded to the field of low frequency (for example, 800 MHz) and high power, such as dielectric resonators for base station channel filters of mobile telephones. In addition, even in high frequency ranges such as dielectric resonators for satellite broadcasting at 4 GHz and 10 GHz, although the Q is lower than that of conventional ultra-high Q materials, the dielectric constant (ε) is large at approximately 38, so It is also expected that the application will expand to areas where it could not be used.

[Brief explanation of drawings]

The drawings show material (sample number 16) according to the embodiment of this invention.
) and the conventional TiO2-ZrO! -3nOz-ZnO
FIG. 3 is a diagram showing the relationship between Q and frequency of -NiO-based materials.

Claims (1)

[Claims] (1) TiO_222~43% by weight, ZrO_238~
58% by weight, SnO_29-26% by weight as the main component,
A high-frequency dielectric ceramic composition containing ZnO in an amount of 7% by weight or less, NiO in an amount of 10% by weight or less, and Sb_2O_5 in an amount of 7% by weight or less.