JP2759274B2 - Dielectric porcelain composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dielectric ceramic composition suitable for high frequency or microwave use.

(Prior art)

In recent years, dielectric porcelain has been widely used in the microwave region, such as in practical use of car phones and personal radios, development of microwave circuits into ICs, and application to gun oscillators. Such high-frequency dielectric porcelain is mainly used as a resonator, but the characteristics required therefor include (1) a wavelength in the dielectric. (2) The dielectric loss at high frequencies is small, (3)
Three characteristics are mainly required: a change in the resonance frequency with respect to the temperature is small, that is, the temperature dependence of the dielectric constant is small and stable.

Conventionally, and BaO-TiO based material as the main dielectric ceramic material, alumina sintered body, MgTiO ₃ -CaTiO ₃ based materials and the like are known.

(Problems to be Solved by the Invention) However, the BaO—TiO ₂ based material has a dielectric constant of 38 to 40.
And the dielectric loss is small, but it is difficult to obtain a single phase having a temperature coefficient of resonance frequency τf = 0, and the change in the dielectric constant and the temperature dependence of the dielectric constant with respect to the composition change is large.
It is difficult to stably control the temperature coefficient τf of the resonance frequency to be small while maintaining a high dielectric constant and a low dielectric loss.

Further, alumina and MgTiO ₃ -CaTiO ₃ -based materials also have disadvantages such as a low dielectric constant and a large temperature change.

[Object of the invention]

The present invention solves the above problems, has high dielectric constant, low loss, and can control the temperature dependence of the resonance frequency in a wide range from zero to positive and negative, and has excellent characteristics for microresonators and capacitors. An object of the present invention is to provide a dielectric ceramic composition.

[Means for solving the problem]

According to the present invention, by adding simultaneously zinc oxide (ZnO) and zirconium oxide (ZrO ₂ ) to a BaO-TiO ₂ -based oxide dielectric material, tin oxide (Sn
It has been found that the above object can be achieved by adding O ₂ ).

 Hereinafter, the present invention will be described in detail.

The dielectric ceramic composition of the present invention has the following formula _{(1-a) (Ba 1} -x Zn x) O · a (Ti 1-yZ Zr y Sn Z) O 2 However, 0.05 ≦ x ≦ 0.5 0.05 ≦ y ≦ 0.4 0.05 ≦ z ≦ 0.4 0.6 ≦ a ≦ 0.9. In the above formula, the x value is for the Ba site
It shows the substitution amount of Zn, y and z show the substitution amount of Zr and Sn with respect to the Ti site, and a shows the ratio of Ba site and Ti site.

In the present invention, the reason for limiting the amount of each substitution and the ratio between the Ba site and the Ti site as described above is that when the x value is less than 0.05 or the x value exceeds 0.5, the temperature dependence of the resonance frequency is required. The nature increases. When the y value is less than 0.05, the loss increases, the Q value decreases, and the y value decreases to 0.4.
When it exceeds, the dielectric constant becomes small.

On the other hand, the addition of SnO ₂ has the effect of reducing the loss,
While increasing the value, the temperature coefficient τf is shifted to the positive side. However, when the amount of SnO ₂ added, that is, the z value exceeds 0.4, the temperature coefficient τf becomes too large.

Further, even if the value a is less than 0.6 or exceeds 0.9, the temperature coefficient τf increases in both cases, which is not preferable.

When producing the dielectric porcelain composition of the present invention, BaO, Ti
O ₂ , ZnO, ZrO ₂ , and SnO ₂ powders were weighed as starting materials, mixed well in a wet or dry system, dried appropriately, and then dried.
A calcination treatment is performed at 0 to 1050 ° C., and a binder and the like are further added to regulate the particle size and then molded.

The molding can be performed by press molding, a doctor blade method, or the like.

Next, the molded body is obtained by firing in an oxidizing atmosphere at 1150 to 1250 ° C., for example, in the air for 1 to 3 hours.

In addition, as a starting material, in addition to the above powders, hydroxides, carbonates, oxalates, and the like that can be converted into oxides by firing can be used.

 Hereinafter, the present invention will be described with reference to the following examples.

〔Example〕

Each powder of BaCO ₃ , TiO ₂ , ZnO, ZrO ₂ , and SnO _{2 having} a purity of 99% or more was weighed so as to have the composition shown in Table 1, and was wet-mixed for 20 hours using an agate ball. After drying this mixture,
Calcination is performed at 950 to 1,050 ° C. for 2 hours, polyvinyl alcohol (about 1% by weight) is added as a binder, and the particles are sized. The obtained powder is pressed at a pressure of 1 ton / cm ^2.
A molded article of × 10 t was obtained. The obtained molded body is 1150 ~ 1250 ° C
For 2 hours in air.

For the obtained sintered body, the dielectric constant quality factor Q value and the temperature coefficient of the resonance frequency were measured at a resonance frequency of 4.5 to 6 GHz by a dielectric cylinder resonator method (post resonator method).

 The results are shown in Table 1.

As is clear from Table 1, the samples of Nos. 1, 5, 8, 12, 13, 16, 17, and 18 whose x, y, z and a values deviate from the range of the present invention have insufficient characteristics. It was something.

In contrast, all of the samples of the present invention exhibited good characteristics, and achieved a dielectric constant εr25 or more, a quality factor Q value of 1000 or more, and a temperature coefficient of resonance frequency | τf | 100 ppm / ° C or less. In particular, 0.3 ≦ x ≦ 0.4, 0.2 ≦ y ≦ 0.4, 0.05 ≦ z ≦ 0.3, 0.7 ≦
When a ≦ 0.8, εr25 or more, Q value 2,000 or more, | τf | 50pp
m / ° C or less was achieved.

〔The invention's effect〕

As described in detail above, the present invention provides high dielectric constant, low loss, and temperature dependence of resonance frequency by simultaneously adding ZnO and ZrO ₂ to BaO-TiO ₂ and further adding SnO ₂ appropriately. Can be controlled in a range including zero, so that a dielectric ceramic composition suitable for a resonator used in a high frequency (microwave) region or a capacitor can be provided.

Claims (1)

(57) [Claims] 1. A formula _{(1-a) (Ba 1} -x Zn x) O · a (Ti 1-yZ Zr y Sn Z) O 2 However, 0.05 ≦ x ≦ 0.5 0.05 ≦ y ≦ 0.4 0.05 ≦ z A dielectric ceramic composition represented by ≦ 0.4 0.6 ≦ a ≦ 0.9.