JPH0334164B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a dielectric ceramic composition for high frequency use. In high frequency regions such as microwaves and millimeter waves, dielectric ceramics are widely used for dielectric resonators, dielectric substrates, 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. These various materials are excellent materials having dielectric constant (ε) of 20 to 40, Q of 3000 to 6000, and temperature coefficient of resonance frequency (τ) of around 0 ppm/° C. at a frequency of 10 GHz. However, recently, the frequency range used has become even higher, and materials with a correspondingly higher Q value are required. In view of the above points, the present inventors conducted extensive research and discovered a dielectric ceramic composition for high frequencies that has a high dielectric constant in the high frequency range and a high Q value. In other words, the gist of this invention is:
It consists of BaO, SnO ₂ , MgO, and Ta ₂ O ₅ , and when expressed as the general formula Ba(Sn _x Mg _y Ta _z )O _7/2-x/2-3y/2 , x, y, and z are 0.04≦x≦0.26, 0.23≦y≦
0.31, 0.51≦z≦0.65 (x+y+z=1)
and if necessary, at least one of the lanthanide rare earth elements R can be added to the oxide R ₂ O ₃
This is a high-frequency dielectric ceramic composition containing 10 mol % or less of . Here, in Ba(Sn _x Mg _y Ta _z )O _7/2-x/2-3y/2 , x, y, and z are limited to the above-mentioned ranges for the following reason. In other words, when x is in the range of 0.04 to 0.26,
When x is less than 0.04 or more than 0.26, Q
This is because it decreases. The reason why y is set in the range of 0.23 to 0.31 is because if y is less than 0.23, Q will decrease and the temperature coefficient (τ) of the resonance frequency will become too large in the positive direction.
Moreover, if it exceeds 0.31, sintering becomes difficult. The reason why z is set in the range of 0.51 to 0.65 is because if z is less than 0.51, sintering becomes difficult or Q decreases, and if z exceeds 0.65, Q decreases. In addition, if necessary, lanthanide oxide R ₂ O ₃
Although a higher Q value can be obtained by adding , the reason why the amount added is limited to 10 mol % or less is because if the amount added exceeds 10 mol %, the Q value decreases. This invention will be explained in detail below with reference to Examples. Example 1 High purity BaCO ₃ , SnO ₂ , MgCO ₃ ,
Ta ₂ O ₅ was weighed so as to obtain porcelain having the composition ratio shown in Table 1, and the weighed raw materials were placed in a ball mill with water and wet mixed for 2 hours. Next, this mixture was dehydrated and dried, and 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. Next, after drying this pulverized material, it was granulated through a 50-mesh mesh, and the resulting powder was powdered at 2000 kg/cm ²
It was molded into a disk with dimensions of 10 mmφ x 2 mmt under a pressure of . Further, this disk was fired at 1500°C for 4 hours to obtain a porcelain sample. The dielectric constant (ε) and Q at a frequency of 10 GHz were measured for the obtained ceramic sample using the dielectric resonator method, and the temperature at the resonant frequency was determined from the temperature change rate of the resonant frequency in the temperature range from 25°C to 85°C. The coefficient (τ) was calculated. The results are shown in Table 1.

[Table] Example 2 Highly purified BaCO ₃ , SnO ₂ , MgCO ₃ ,
Ta ₂ O ₅ , and lanthanide oxide La ₂ O ₃ ,
CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Dy ₂ O ₃ ,
Using at least one of Ho ₂ O ₃ and Er ₂ O ₃ , weighing so as to obtain porcelain having the composition ratio shown in Table 2,
The weighed raw material was treated in the same manner as in Example 1 to obtain a porcelain sample. The obtained porcelain sample was measured in the same manner as in Example 1,
The results are shown in Table 2.

【table】

[Table] Items marked with * in Tables 1 and 2 are outside the scope of this invention, and the others are within the scope of this invention. In Table 1, sample numbers 8, 9, 10, 11,
12, 13 are x, y of Ba(Sn _x Mg _y Ta _z )O _7/2-x/2-3y/2 ,
The value of z is outside the range of this invention, and sintering is difficult or the properties are deteriorated. In Table 2, sample numbers 17, 21, 25, 29,
33, 37, 41 are lanthanide oxides R ₂ O ₃ at 10.0
This is an example in which it is added in an amount exceeding mol %, and it is excluded from the scope of this invention because the Q decreases.
In addition, sample numbers 42, 43, 44, 45, 46, and 47 are Ba
The x, y, and z values of (Sn _x Mg _y Ta _z ) O _7/2-x/2-3y/2 are outside the scope of this invention, and sintering may be difficult or the properties may deteriorate. It is something that Note that the characteristics are not shown for sample numbers 8 and 9 in Table 1 and sample numbers 42 and 43 in Table 2, because sufficiently sintered porcelain cannot be obtained and the characteristics cannot be measured. This is because it was warm. In addition, in Example 2, lanthanide oxide
R ₂ O ₃ as La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ ,
Although Sm ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , and Er ₂ O ₃ are added, it has been confirmed that similar results can be obtained by adding other lanthanide oxides. As described above, according to the present invention, it is possible to obtain a dielectric ceramic composition for high frequencies that has a high dielectric constant and a high Q value that has not been obtained conventionally. Furthermore, if a lanthanide-based oxide is added as necessary, a high-frequency dielectric ceramic composition exhibiting an even higher Q value can be obtained. Furthermore, by appropriately selecting the composition, the temperature coefficient (τ) of the resonance frequency can be set to 0 ppm/°C. Therefore, according to the invention, a dielectric resonator,
It is possible to provide high-frequency dielectric ceramics useful for applications such as dielectric adjustment rods and dielectric substrates.

Claims (1)

[Claims] 1 Consisting of BaO, SnO ₂ , MgO, Ta ₂ O ₅ , expressed as the general formula Ba(Sn _x Mg _y Ta _z )O _7/2-x/2-3y/2 , x, y, z are 0.04≦x≦0.26, 0.23≦y
≦0.31, 0.51≦z≦0.65 (however, x+y+z=
A high frequency dielectric ceramic composition falling within the range of 1). 2 Consists of BaO, SnO ₂ , MgO, Ta ₂ O ₅ , and when expressed as the general formula Ba(Sn _x Mg _y Ta _z ) O _7/2-x/2-3y/2 , x, y, z is 0.04≦x≦0.26, 0.23≦y
≦0.31, 0.51≦z≦0.65 (however, x+y+z=
1), and at least one of the lanthanide rare earth elements R is 10 in terms of oxide R ₂ O ₃
A high frequency dielectric ceramic composition containing an additive amount of not more than mol%.