JP3076216B2 - Dielectric ceramics for microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to dielectric ceramics for microwave, especially having a large specific dielectric constant epsilon _r, the unloaded Q (Q _u) is large and by varying the composition, the resonance frequency The present invention relates to a dielectric ceramic for microwaves, which can change the temperature coefficient τ _f to an arbitrary value centering on 0 ppm / ° C.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
"29th Applied Physics-related Lectures 2a-I-
4 P763 (1982). 2. Description of the Related Art In recent years, microwave dielectric resonators and dielectric filters have been widely used for automobile telephones, mobile telephones, and satellite broadcast receivers. The dielectric material used in such an application has a large relative permittivity ε _r and a no-load Q (Q _u ), and the temperature coefficient τ _f of the resonance frequency is 0 ppm / ° C. by changing the composition. What can be set to any positive or negative value centered on? Conventionally, such ceramics include BaO—TiO ₂ , ZrO ₂ —S
there was nO-TiO ₂ system.

[0003]

However, in the above ceramics, the temperature coefficient τ _f of the resonance frequency is 0 p
With a value near pm / ° C., the value of the relative permittivity ε _r was satisfactory, but the unloaded Q (Q _u ) was not sufficiently large. Therefore, an apparatus incorporating a device using these materials has disadvantages such as a large loss in transmission and reception, and cannot be said to have sufficiently satisfactory characteristics.

The present invention has been made in order to improve these _{problems, and} has a large relative permittivity ε _r and a composition ratio in which the temperature coefficient τ _f of the resonance frequency is close to 0 ppm / ° C. It is an object of the present invention to provide a microwave dielectric ceramic having a very large load Q ( _Qu ).

[0005]

In order to achieve the above object, a microwave dielectric ceramic according to the present invention comprises barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ). The composition formula of the main component is Ba _x
(Co _y Nb _z ) O ₃ , where x, y, and z are mol%, respectively, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.3 mol% x + y + z = 100 mol% (1) 0.1 mol as a sub-component with respect to 1 mol of the main component
A mole or less (but not including 0 mole) of aluminum oxide (Al ₂ O ₃ ) is added.

(2) With respect to 1 mol of the main component, 0.1 mol or less (but not 0 mol) of titanium oxide (TiO ₂ ) and 0.03 mol or less (provided that 0 mol (Not including) is added.

[0007]

According to the present invention, the main component is a composition represented by the above-described composition formula. (1) As an auxiliary component, 0.1 mol or less (but not including 0 mol) of aluminum oxide (Al By adding ₂ O ₃ ), the relative permittivity ε _r and the no-load Q are large in the microwave region, and the temperature coefficient τ _f of the resonance frequency is reduced by 0 p
Even when the composition is around pm / ° C., the no-load Q has a large value. For this reason, it is effective for miniaturization and low loss of the dielectric resonator and the dielectric filter in the microwave band.

Furthermore, the temperature coefficient tau _f of the resonance frequency, it is possible to easily change to a positive or negative arbitrary value, the relationship between the deviation and the like of other devices phase, the temperature coefficient of resonant frequency tau _f However, even when a value other than 0 ppm / ° C. is required, by changing the addition amount of Al ₂ O ₃ ,
The temperature coefficient τ _f of the resonance frequency can be set to any value from negative to positive.

(2) 0.1 mol or less (but not 0 mol) of titanium oxide (TiO ₂ ) and 0.03 mol or less (but not 0 mol) of copper oxide (CuO) as subcomponents ), The relative permittivity ε _r and the no-load Q are large in the microwave region, and the no-load Q is a large value even when the temperature coefficient τ _f of the resonance frequency is set to be around 0 ppm / ° C. have. For this reason,
This is effective for miniaturization and low loss of a microwave resonator and a dielectric filter in a microwave band.

Furthermore, the temperature coefficient tau _f of the resonance frequency, it is possible to easily change to a positive or negative arbitrary value, the relationship between the deviation and the like of other devices phase, the temperature coefficient of resonant frequency tau _f However, even when a value other than 0 ppm / ° C. is required, the temperature coefficient τ _f of the resonance frequency can be set to an arbitrary value from negative to positive by changing the amount of TiO ₂ added.

[0011]

The first embodiment of the present invention will be described below. Starting materials include chemically pure barium oxide (B
aO), cobalt oxide (CoO), niobium oxide (Nb ₂
O _5), using the aluminum oxide (Al ₂ O _3), and Hyoryou exactly as to obtain the composition shown in Table 1 shown below.

This was wet-mixed with pure water for 20 hours using a plastic pot mill and zirconia balls. After dehydrating and drying this mixture, it was calcined in a magnesia container at 1200 ° C. for 3 hours in air. The calcined product was wet-pulverized in the same manner as in the mixing step, and then dehydrated and dried to obtain fine powder. A binder was added to the powder and mixed sufficiently with the powder to obtain a granulated powder. This granulated powder is molded using a mold and a hydraulic press at a molding pressure of 1 to 3 t / c.
20mm diameter in m ^2, and to produce a disc-shaped body having a thickness of 12 mm.

The molded body thus obtained is placed in a magnesia container and heated at a temperature of 1350 to 1500 ° C. for 5 minutes.
Calcination was performed in air for a time to obtain a dielectric ceramic. After polishing this ceramic to a predetermined frequency, the dielectric properties were measured by the following method. The dielectric constant of the dielectric ceramics epsilon _r and unloaded Q (Q _u) was measured by hacking Coleman method.

The temperature coefficient τ _f of the resonance frequency is 20 ° C.
, The resonance frequencies f (−40) and f (8) at temperatures of −40 ° C. and 80 ° C.
0) and the temperature difference ΔT (here, ΔT at −40 ° C. and 80 ° C.)
= 120 ° C) according to the following equation (1). The measurement frequency in these measurements was about 5 GHz.

Τ _f = {f (80) −f (−40)} / {f (20) × 120} (1) Table 1 shows the measurement results of the dielectric properties of each composition.

[0016]

[Table 1]

In the table, the sample Nos.
Is a comparative example outside the scope of the present invention, and other samples N
o. Are examples of the present invention. FIG. 2 to Sample No. The relationship of the mol% of the main component in the range of 15 is shown. According to the results of FIG. 1 and Table 1, BaO is 59.5.
When it is less than mol%, the sample No. 7, the no-load Q was as small as 1300, and when it exceeded 61.8 mol%, the sample No. As in the case of 1, the no-load Q is too small, which is inappropriate.

When the content of CoO is less than 19.1 mol%, the sample No. The no-load Q becomes smaller as shown in FIG.
If it exceeds 0.6 mol%, the sample no. 10, No. Fifteen
In this case, the no-load _Qu is too small, which is inappropriate.
Further, when Nb ₂ O ₅ is less than 19.1 mol%, Sample No. 2, No. As shown in Sample No. 15, when the unloaded Q was small and exceeded 20.3 mol%, Sample No. 7, no.
9, No. As in the case of 11, the no-load _Qu is also small, which is inappropriate.

Therefore, BaO is 59.5-61.8.
The preferred range is 1 mol%, the range of CoO is 19.1 to 20.6 mol%, and the range of Nb ₂ O ₅ is 19.1 to 20.3 mol%. For Al ₂ O ₃ as a subcomponent with respect to the main component, sample No. 16-20
As shown in the figure, the relative dielectric constant ε
_r shows an increasing trend, but the amount of change is small. Further, the temperature coefficient τ _f of the resonance frequency is such that the addition amount of Al ₂ O ₃ is 0.00
From -4.3 ppm / ° C at 5 mol (Sample No. 16) to 80.5 ppm at 0.5 mol (Sample No. 20)
/ ° C.

Furthermore, the 10000 in the unloaded Q _u is the amount of Al ₂ O ₃ added is 0.005 mol (Sample No.16), reduced to 4900 in 0.1 mol (Sample No.19), The amount of Al ₂ O ₃ added was 0.5 mol (sample No.
In the case of 20), the value rapidly decreases to 1000, which does not meet the purpose of the present invention. Thus, the addition amount of Al ₂ O ₃ is suitably up to 0.1 mol.

As described above, Ba _x (Co _y Nb _z ) O
₃ is a dielectric ceramic obtained by adding Al ₂ O ₃ to x =
Around 60 mol%, y = 20 mol%, z = 20 mol%,
In a composition in which 0.005 mol of Al ₂ O ₃ is added to 1 mol of the main component, the largest no-load Q can be obtained. Also, by changing the addition amount of Al ₂ O ₃ ,
The temperature coefficient τ _f of the resonance frequency changes to an arbitrary value from negative to positive.

In the first embodiment, the characteristics are measured using a disk-shaped molded body having a diameter of 20 mm and a thickness of 12 mm. However, when applied to a dielectric resonator or a dielectric filter, the characteristics are measured. A disk-shaped molded body having a different thickness or a molded body having another shape such as a rectangular parallelepiped may be used. Also, processing,
The shape may be changed by polishing. Next, a second embodiment of the present invention will be described.

Starting materials include chemically pure barium oxide (BaO), cobalt oxide (CoO), niobium oxide (Nb ₂ O ₅ ), titanium oxide (TiO ₂ ), and copper oxide (C
uO) and accurately weighed to the composition shown in Table 2 below. This was wet-mixed with pure water for 20 hours using a plastic pot mill and zirconia balls. After dehydrating and drying this mixture, it was calcined in a magnesia container at 1200 ° C. for 3 hours in air. The calcined product was wet-pulverized in the same manner as in the mixing step, and then dehydrated and dried to obtain fine powder. A binder was added to the powder and mixed sufficiently with the powder to obtain a granulated powder. This granulated powder is molded using a mold and a hydraulic press at a molding pressure of 1 to 3 t / c.
20mm diameter in m ^2, and to produce a disc-shaped body having a thickness of 12 mm.

The molded body thus obtained is placed in a magnesia container and heated at a temperature of 1350 to 1500 ° C. for 5 minutes.
Calcination was performed in air for a time to obtain a dielectric ceramic. After polishing this ceramic to a predetermined frequency, the dielectric properties were measured by the following method. The dielectric constant of the dielectric ceramics epsilon _r and unloaded Q (Q _u) was measured by hacking Coleman method.

The temperature coefficient τ _f of the resonance frequency is 20
-40 ° C based on the resonance frequency f (20) at
And the resonance frequency f (−40) at a temperature of 80 ° C., f
(80) and the temperature difference ΔT (here, −40 ° C. and 80 ° C.)
△ T = 120 ° C.) according to the above equation (1). The measurement frequency in these measurements is about 5G
Hz.

Table 2 shows the measurement results of the dielectric properties of each composition.

[0027]

[Table 2]

The sample No. marked with * in Table 2 Is a comparative example outside the scope of the present invention, and other sample Nos. Are examples of the present invention. FIG. 2 to sample N
o. The relationship of the mol% of the main component in the range of 15 is shown. FIG.
According to the results shown in Table 2 and Table 2, when the content of BaO is less than 59.5 mol%, Sample No. As shown in Sample No. 7, the no-load Q was as small as 900, and when it exceeded 61.8 mol%, Sample No. As in the case of 2, the no-load Q is too small, which is inappropriate. Further, when CoO becomes less than 19.1 mol%, the sample N
o. 2, the unloaded Q becomes smaller, and 20.6 mol%
Exceeds the sample No. 10, No. As in the case of 15, the no-load Q is too small, which is inappropriate.

Further, when the content of Nb ₂ O ₅ is less than 19.1 mol%, the sample No. 2, No. No load Q like 15
Is smaller than 20.3 mol%, sample No.
7, no. 9, No. As in the case of 11, the no-load Q is too small, which is inappropriate. Therefore, BaO is 59.5.
-61.8 mol%, CoO is 19.1-20.6.
Mol%, Nb ₂ O ₅ is 19.1 to 20.3 mol%
Are preferred ranges.

Further, Ti as a subcomponent with respect to the main component
For O ₂ , sample No. As shown in 16-20,
If the amount is gradually increased, the relative dielectric constant epsilon _r, as shown in the increasing trend, variation is small. Also, the temperature coefficient τ of the resonance frequency
_f is 0.005 mol of TiO ₂ added (Sample No. 1).
From -0.3 ppm / ° C in 6), 0.5 mol (sample N
o. 20) to 63.2 ppm / ° C. Further, the unloaded Q was changed from 9800 when the TiO ₂ addition amount was 0.005 mol (sample No. 16) to 0.1 mol (sample N).
o. 19), it becomes 4300, and when the amount of TiO ₂ added becomes 0.5 mol (sample No. 20), it becomes 1400.
, And it does not meet the purpose of the present invention. Thus, the addition amount of TiO ₂ is suitably up to 0.1 mol.

Further, Cu as a subcomponent with respect to the main component
O is the sample No. 17, 21 to 26, there is no large change in the relative dielectric constant ε _{r, and} there is no large change in the temperature coefficient τ _f of the resonance frequency. The no-load Q was measured when the CuO addition amount was 0.0005 mol (sample N
o. 21) from 6000 to 0.001 mol (sample N
o. 17), increased to 8100, but decreased to more than 0.01 mol, and decreased to 0.03 mol (sample No. 2).
When it becomes 4100 and 0.05 mol (sample No. 26) in 5), it rapidly decreases to 1900 and does not meet the purpose of the present invention. Thus, the addition amount of CuO is appropriately up to 0.03 mol.

As described above, Ba _x (Co _y Nb _z ) O
_The dielectric ceramic obtained by adding TiO ₂ to ₃ has x = 6
Near 0 mol%, y = 20 mol%, and z = 20 mol%, the largest unloaded Q can be obtained in a composition in which 0.005 mol of TiO ₂ is added to 1 mol of the main component. Also, by changing the amount of TiO ₂ added, the temperature coefficient τ _f of the resonance frequency changes from negative to positive to an arbitrary value. A large no-load Q can be obtained by adding CuO.

In this embodiment, the diameter is 20 mm and the thickness is 12 mm.
The characteristics are measured using a mm-shaped disk-shaped molded body, but when applied to a dielectric resonator or a dielectric filter,
A disk-shaped molded body having a different diameter and thickness or a molded body having another shape such as a rectangular parallelepiped may be used. The shape may be changed by processing or polishing. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0034]

As described above, according to the present invention, the following effects can be obtained. (1) According to the dielectric ceramic according to the first aspect, even when the composition is such that the relative dielectric constant ε _r and the no-load Q are large in the microwave region and the temperature coefficient τ _f of the resonance frequency is around 0 ppm / ° C. , No-load Q has a large value. For this reason, it is effective for miniaturization and low loss of the dielectric resonator and the dielectric filter in the microwave band.

Furthermore, since it is possible to easily change the temperature coefficient tau _f of the resonance frequency to any positive or negative value, the relationship between the deviation and the like of other devices phase, the temperature coefficient tau _f of the resonant frequency , Even when a value other than 0 ppm / ° C. is required, by changing the amount of Al ₂ O ₃ added,
The temperature coefficient τ _f of the resonance frequency can be set to any value from negative to positive.

(2) According to the dielectric ceramic of the second aspect, the relative dielectric constant ε _r and the no-load Q are large in the microwave region, and the temperature coefficient τ _f of the resonance frequency is 0 ppm.
Even when the composition is close to / ° C, the no-load Q has a large value. For this reason, it is effective for miniaturization and low loss of the dielectric resonator and the dielectric filter in the microwave band.

Furthermore, since it is possible to easily change the temperature coefficient tau _f of the resonance frequency to any positive or negative value, the relationship between the deviation and the like of other devices phase, the temperature coefficient tau _f of the resonant frequency Even when a value other than 0 ppm / ° C. is required, the temperature coefficient τ _f of the resonance frequency can be changed from negative to positive by changing the amount of TiO ₂ added.

[Brief description of the drawings]

FIG. 1 shows sample No. 1 of the present invention. 2 to Sample No. 1
FIG. 6 is a diagram showing a relationship of mol% of a main component in a range of 5;

Continuation of front page (72) Inventor Hideki Ono 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) References JP-A-6-267332 (JP, A) (58) Investigation Field (Int. Cl. ⁷ , DB name) C04B 35/495 CA (STN)

Claims (2)

(57) [Claims] 1. A composition formula of a main component comprising barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ) is represented by Ba _x (Co _y Nb _z ) O ₃ , wherein x, y and z are mol%, respectively, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.3 mol% x + y + z = 100 mol% Microwave, characterized in that 0.1 mol or less (but not 0 mol) of aluminum oxide (Al ₂ O ₃ ) is added as a subcomponent to 1 mol of the main component. For dielectric ceramics. 2. A composition formula of a main component comprising barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ) is represented by Ba _x (Co _y Nb _z ) O ₃ , wherein x, y and z are mol%, respectively, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.3 mol% x + y + z = 100 mol% 0.1 mol or less (but not 0 mol) of titanium oxide (TiO ₂ ) and 0.03 mol or less (but not including 0 mol) as subcomponents per 1 mol of the main component. A) dielectric ceramics for microwaves, characterized by adding copper oxide (CuO).