JPH06103813A - High frequency dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To obtain a high frequency dielectric ceramic composition having high dielectric constant, large Q value and a small temperature factor for resonant frequency made variable by changing the composition of the dielectric ceramic. CONSTITUTION:A high frequency dielectric ceramic is formed of BaO, TiO2, Nd2O3, Bi2O3, Al2O3) and MnO, wherein when a main component is represented by xBaO+yTiO2+yNd2O3, x, y and z are within ranges represented respectively by 9=<x=<18, 65=<y=<73 and 14=<z=<19 (x+y+z=100), Bi2O3 of 3.0-11.0 weight percent, Al2O3 of 0.1-2.0 weight percent and MnO of 0.1-1.0 weight percent added as additives.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric ceramic composition, and in particular, has a large relative permittivity ε, a large Q in a microwave frequency band, and a temperature coefficient (hereinafter referred to as TCf) of a resonance frequency. The present invention relates to a dielectric ceramic composition for a high frequency dielectric resonator, which is small and whose TCf can be changed by changing the composition.

[0002]

2. Description of the Related Art A conventional dielectric ceramic composition used for a high-frequency dielectric resonator is BaO--TiO ₂
-Nd ₂ O ₃ -Bi ₂ O ₃ are known.

[0003]

By the way, when a high frequency dielectric resonator is constructed with such a conventional composition, T
Cf was +10 ppm or more, TCf in the vicinity of 0 ppm could not be obtained, and Q in the range of +10 to +30 ppm was 1000 or less, which was not a practical Q when used as a dielectric element.

Moreover, there is a problem in the temperature stability of the formed dielectric resonator. In addition, the conventional composition has a problem that it cannot meet a wide range of needs as a dielectric material because the Q value is slightly low. In addition, this composition
The sinterability was not so good, which caused the decrease of the ε and Q value.

Therefore, an object of the present invention is to have a large relative permittivity ε, a large Q in the microwave frequency band, and a TC
f is small, and by changing its composition, this T
It is an object of the present invention to provide a high frequency dielectric porcelain composition capable of changing Cf.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies and as a result, have found that BaO, TiO ₂ , Nd ₂ O ₃ and Bi ₂ O as high frequency dielectric ceramic compositions.
₃ , a composition consisting of Al ₂ O ₃ and MnO, the composition formula of which is expressed as xBaO + yTiO ₂ + zNd ₂ O ₃ is 9 ≦ x ≦ 18 mol% 65 ≦ y ≦ 73 mol% 14 ≦ z ≦ 19 mol % (However, x + y + z = 10
0) In the range of the main component, Bi ₂ O ₃ is added to 3.1 to 11.0 wt% Al ₂ O ₃ is added to 0.1 to 2.0 wt% MnO is added to 0.1 to 1.0 wt%. It has been found that a composition is obtained.

[0007]

The dielectric ceramic composition for high frequencies described above has an ε of 65.
In addition to the above, the Q without load is as large as 1000 or more, and in addition, TCf is -5 to +30 ppm, which is close to 0, and the range is small. This makes it possible to obtain a dielectric ceramic composition which is useful for high frequency dielectric resonators.

[0008]

EXAMPLES Examples of the present invention will be described below. (1) First Example BaCO ₃ , TiO ₂ , Nd ₂ O ₃ and B as starting materials
i ₂ O ₃ , Al ₂ O ₃ and MnO are weighed and mixed so that the final composition after sintering is as shown in Table 1 below.

This differential powder is wet mixed in a ball mill for 20 hours, dehydrated and dried. Next, the dehydrated and dried composition is calcined at 1000 to 1200 ° C. for about 2 hours, and then the calcined body is roughly pulverized and further wet pulverized.

An appropriate amount of binder is added to the powder thus obtained and granulated. Next, after press-molding this into a columnar shape with a diameter of 12.7 mm and a height of 7 mm, 1200-1400
Bake at about 2 hours.

Then, the dielectric ceramic thus obtained is processed to have a diameter of 10 mm and a height of 5 mm, and various characteristics shown in Table 1 are measured. The measuring method is 4 ° C. at 25 ° C. by the TE ₀₁₁ mode of the resonator constituted by sandwiching the cylindrical dielectric obtained as described above between two parallel metal plates.
Was performed at Hz to determine ε and Q.

Further, TCf is obtained from the change in resonance frequency due to the temperature change from -40 ° C to + 80 ° C. The measurement results thus obtained are shown in Table 1. The samples marked with * in Table 1 are outside the scope of the present invention, but are presented for comparison with those of the examples of the present invention.

[0013]

[Table 1]

As is clear from Table 1, the dielectric ceramic composition of the present invention has a large ε of 60 or more and a Q of 1000 or more, and has a relatively small TCf value of -5 to +30 ppm. Further, even if the composition of the main component is the same, TCf can be changed from the − side to the + side by changing the amount of the additive (see Sample Nos. 15 to 18 in Table 1).

Next, the reasons for limiting the composition range of the high frequency dielectric ceramic composition of the present invention will be explained. The molar ratio x of BaO is 9
When it is less than Q, Q is considerably small, which is not practical (see Sample No. 12 in Table 1). When x exceeds 18, Q is considerably small and TCf is large on the + side (see Sample No. 10 in Table 1).

If the molar ratio y of TiO ₂ is less than 65, the sinterability is poor, and both ε and Q are considerably small and impractical (see sample No. 13 in Table 1). When y exceeds 73, the values of ε and Q are too small to be practical (see Sample No. 12 in Table 1), or the value of Q is small (see Sample No. 11 in Table 1).

When the molar ratio z of Nd ₂ O ₃ is less than 14, Q is small and it is not practical (Sample No. 10, 1 in Table 1).
1). Also, when this z exceeds 19, this is also ε,
Q is considerably small and not suitable for practical use (Sample No. 12 in Table 1,
13).

When the added amount of Bi ₂ O ₃ is less than 3 wt%, TCf is greatly increased to the + side (Sample No. 2 in Table 1).
0, 21). Further, when this addition amount exceeds 11 wt%, Q becomes small (see sample No. 24 in Table 1).

When the amount of Al ₂ O ₃ added is less than 0.1 wt%, TCf greatly increases to the + side (Sample No. 14 in Table 1).
reference). Further, when the added amount exceeds 2 wt%, ε and Q become small (see Sample No. 19 in Table 1).

When the amount of MnO added is less than 0.1 wt%, the sinterability is poor and the values of ε and Q are small (Sample No. 1 in Table 1).
25). And when this addition amount exceeds 1.0 wt%, Q
Not only decreases but TCf also increases (see sample No. 28 in Table 1).

(2) Second Embodiment A second embodiment of the invention of claim 2 of the claims of the present invention
As described below. As a starting material, BaCO₃, TiO
₂, Nd₂O₃, La₂O₃, Pr₆O ₁₁, Bi
₂O₃, Al₂O₃, MnO composition after final sintering
Are weighed and mixed as shown in Table 2 below.
It

Then, a dielectric ceramic composition is manufactured by the same manufacturing process as in the first embodiment, and various characteristics shown in Table 2 are measured. The measuring method and the measuring conditions are the same as those in the first embodiment.

Table 2 shows the obtained measurement results. Table 2
Of these, those marked with * are outside the scope of the present invention, but are presented for comparison with those of the examples of the present invention.

[0024]

[Table 2]

As is apparent from Table 2, the composition of claim 2 of the present invention, that is, the composition of the second embodiment, has ε of 70 or more and Q
TCf is 3 despite the large value of 1000 or more.
It is a relatively small value of 0 ppm or less.

Next, the composition range of the dielectric ceramic composition according to the second aspect of the present invention will be described. The same components as those of the first embodiment, that is, the invention of claim 1 will be omitted. N
When the ratio m of La ₂ O ₃ in which a part of d ₂ O ₃ is substituted becomes larger than 0.1, not only Q becomes smaller but TCf becomes larger on the + side (see Sample Nos. 6 and 9 in Table 2). .

Further, Pr ₆ O in which a part of Nd ₂ O ₃ is substituted
_When the ratio n of ₁₁ becomes larger than 0.1, TCf becomes +
It increases toward the side (see Sample Nos. 3 and 10 in Table 2).

[0028]

The high frequency dielectric ceramic composition of the present invention comprises:
Since the relative dielectric constant is large and the TCf is relatively small, it becomes possible to meet the demand for frequency temperature stability that is more severe than that of the conventional dielectric ceramic composition.

By changing the amount of Al ₂ O ₃ or Bi ₂ O ₃ added, the value of TCf can be adjusted to 0 ppm +
It has become possible to appropriately select the side or the-side. Furthermore Q
The value of is about 10 to 20% larger than that of the conventional composition, and can be low loss. This is Al
_This is considered to be the effect of the addition of ₂ O ₃ .

By adding MnO, the sinterability is improved, and the decrease of ε caused by the improvement of TCf can be covered thereby. The dielectric porcelain composition of the present invention having such excellent characteristics can be used as a material for a resonant element such as a bandpass filter represented by an automobile telephone duplexer, an interstage filter, a voltage controlled oscillation element, or the like. it can. Further, it can be used as a microwave integrated circuit board and a capacitor material for high frequency power.

Claims (2)

[Claims] 1. A composition comprising barium oxide, titanium oxide, neodymium oxide, bismuth oxide, aluminum oxide and manganese oxide, wherein the composition formula is expressed as xBaO + yTiO ₂ + zNd ₂ O _3, and 9 ≦ x ≦ 18 mol % 65 ≦ y ≦ 73 mol% 14 ≦ z ≦ 19 mol% (where x + y + z = 10
To range the main component of which is 0), high frequency dielectric, characterized in that Bi ₂ O ₃ and 3.0 ~11.0 wt% Al ₂ O ₃ is added each 0.1 to 1.0 wt% of 0.1 to 2.0 wt% MnO Porcelain composition. 2. In the composition formula of the main component, a part of neodymium oxide is replaced with at least one of lanthanum oxide and praseodymium oxide, and the composition formula is expressed as xBaO + yTiO ₂ + z {(Nd ₂ O ₃ ) _1-mn (La
_2. The high frequency dielectric ceramic composition according to claim 1, wherein when expressed as ₂ O ₃ ) _m (Pr ₆ O ₁₁ ) _n }, 0 ≦ m ≦ 0.10 0 ≦ n ≦ 0.10. .