JPH0447921B2 - - Google Patents

Description

[Detailed description of the invention]

(1) Industrial Application Field This invention relates to a dielectric ceramic composition having a high Q value in a high frequency region such as microwaves and millimeter waves. (2) Prior Art In high frequency regions such as microwaves and millimeter waves, dielectric ceramics are widely used in dielectric resonators, dielectric substrates for MIC, and the like. Conventionally, as this type of dielectric porcelain, for example,
ZrO ₂ −SnO ₂ −TiO ₂ material, BaO−TiO ₂ material,
(Ba, Sr) (Zr, Ti) O ₃ -based materials, Ba (Zn, Ta)
O ₃ type materials are known. However, these various materials all have frequency
Dielectric constant (ε) is 20 to 40 and Q is 3000 at 10GHz
~6000, the temperature coefficient (τf) of the resonant frequency is Oppm/
It is also known to be an excellent material with properties around ℃. (3) Problems to be Solved by the Invention Recently, however, the frequency range used has become even higher, and there is a corresponding demand for materials with even higher Q values. The applicant of this application has previously applied for a material with such a high Q value in the patent application filed in 1982-
In No. 231159, Ba(Sn _x Mg _y Ta _z )
O When expressed as _7/2-x/2-3y/2 , x, y, and z are respectively 0.04≦x≦0.26, 0.23≦y≦0.31, 0.51≦z≦
We are proposing a high frequency dielectric ceramic composition in the range of 0.65 (x+y+z=1). However, in this high-frequency dielectric porcelain assembly, when trying to set the temperature coefficient of the resonant frequency to an arbitrary value centered on Oppm/℃, the composition ratio of the main components is changed depending on the value of the temperature coefficient of the resonant frequency. However, the materials have to be mixed again, which makes manufacturing quite time-consuming. Furthermore, with regard to dielectric constant, materials with even higher dielectric constants are required. (4) Means for Solving the Problems In view of the above points, the inventors of the present invention have conducted extensive research and found that the present inventors have a high dielectric constant in the high frequency range and a Q
They have discovered a high-frequency dielectric ceramic composition that has a high value and can obtain an arbitrary value for the temperature coefficient of the resonant frequency around Oppm/°C. That is, the gist of this invention is that BaO,
It consists of SnO ₂ , MgO, and Ta ₂ O ₅ , which is expressed by the general formula Ba
(Sn _x Mg _y Ta _z ) O When expressed as _7/2-x/2-3y/2 , x,
y and z are respectively 0.04≦x≦0.26, 0.23≦y≦0.31,
The dielectric ceramic composition for high frequency is in the range of 0.51≦z≦0.65 (however, x+y+z=1), and 70 atomic percent or less of Mg is replaced by Zn. (5) Effect Here, in Ba(Sn _x Mg _y Ta _z ) O _7/2-x/2-3y/2 ,
The reason why x, y, and z are each limited to the above-mentioned ranges is as follows. In other words, the reason for setting x in the range of 0.04 to 0.26 is that x is
This is because Q decreases if it is less than 0.04 or exceeds 0.26, and the reason why y is set to 0.23 to 0.31 is because
This is because if it is less than 0.23, Q will decrease and the temperature coefficient (τf) of the resonance frequency will become too large in the positive direction, and if it exceeds 0.31, sintering will become difficult. Furthermore, z is set in the range of 0.51 to 0.65 because if it is less than 0.51, sintering becomes difficult or Q
This is because Q decreases and when it exceeds 0.65, Q decreases. Also, Ba(Sn _x Mg _y Ta _z )O _7/2-x/2-3y/2 Mg is Zn
The purpose of replacing with is to increase the dielectric constant and
By moving the temperature coefficient (τf) of the resonant frequency to the negative side,
At that time, the purpose is to control τf by appropriately changing the amount of substitution and obtain a porcelain useful for temperature compensation.
The conditions below are such that if it exceeds 70 atomic %, sintering becomes difficult, or Q is greatly reduced at the same composition point, or Q is greatly reduced at the same composition point and τf becomes too large on the negative side. This is to do so. (6) Examples This invention will be explained in detail below using examples. Example 1 Highly purified BaCO ₃ , SnO ₂ , MgCO ₃ as raw materials,
Ta ₂ O ₅ and ZnO were weighed so as to obtain porcelain having the composition ratio shown in Table 1, and the weighed raw materials were put into a rubber-lined ball mill with water and wet-mixed for 2 hours. Next, this mixture was dehydrated and dried, then calcined at 1200° C. for 2 hours, and the calcined product was placed in a ball mill together with water and an organic binder and wet-pulverized for 2 hours. The pulverized product was then dried and granulated through a 50-mesh mesh, and the resulting powder was molded into a disk having dimensions of 10 mmφ x 5 mmt under a pressure of 2000 kg/cm ² . Further, this disk was fired at 1500°C for 4 hours to obtain a porcelain sample. For the porcelain sample thus obtained, the frequency
The dielectric constant (ε) and Q at 10 GHz were measured using the dielectric resonator method, and the temperature coefficient (τf) of the resonant frequency was calculated from the temperature change rate of the resonant frequency in the temperature range from 25°C to 85°C. The results are shown in Table 1. The results are shown in Table 1. It should be noted that those marked with * in Table 1 are outside the scope of the claims of this invention.

【table】

[Table] In the above table, sample numbers 29 to 40 are Ba(Sn _x
Any value of x, y, or z of Mg _y Ta _z ) O _7/2-x/2-3y/2 is outside the scope of this invention, and sintering is difficult or the properties are deteriorated. This is what we are doing. Sample numbers 1, 5, 9, 13, 17, 21, and 25 contain Mg.
It is not substituted with Zn and is outside the scope of this invention. Also, sample numbers 4, 8, 12, 16, 20, 24, and 28 are
This is an example in which the amount of Mg substituted by Zn exceeds 70 atomic %, and is outside the scope of this invention. Specifically, sample numbers 8, 24, and 28 are difficult to sinter, and sample numbers 4 and 12 have a significantly lower Q at the same composition point.
Samples Nos. 16 and 20 have a significantly lower Q at the same composition point, and τf is too large on the negative side. (7) Effects As detailed above, the present invention has a high dielectric constant and a high Q that could not be obtained conventionally.
It is possible to obtain a high-frequency dielectric ceramic composition that exhibits a Ba
(Sn _x Mg _y Ta _z ) O _7/2-x/2-3y/2 Finely adjust the temperature coefficient (τf) of the resonance frequency of the ceramic composition by appropriately changing the amount of Mg to be replaced with Zn. We can easily calculate τf by
Since it can be adjusted to any value centered around Oppm/°C, it is effective for temperature compensation. Therefore, according to the present invention, it is possible to provide a high frequency dielectric ceramic composition useful for applications such as dielectric resonators, dielectric adjustment rods, and dielectric substrates.

Claims (1)

[Claims] 1 Consisting of BaO, SnO ₂ MgO, Ta ₂ O ₅ , which is represented by the general formula Ba(Sn _x Mg _y Ta _z ) O _7/2-x/2-3y/2 , x, y, z are each 0.04≦x≦
0.26, 0.23≦y≦0.31, 0.51≦z≦0.65 (however,
x+y+z=1), and 70 atomic percent or less of Mg is substituted with Zn.