JPH08106814A - Dielectric ceramics for microwave - Google Patents

Abstract

PURPOSE: To make relative permittivity large and make no-load Q large even with a composition whose resonant frequency temperature coefficient is in the vicinity of 0ppm/ deg.C by adding a predetermined amount of titanium dioxide and magnesium oxide as accessory components to 1mol of main component. CONSTITUTION: Chemically high purity barium carbonate(BaCo3 ), cobalt oxide(CoO), niobium oxide(Nb2 O5 ), titanium dioxide(TiO2 ), and magnesium oxide(MgO) are used as starting raw material. The composition formula of a main component is expressed by (BaO)x.(CoO)y.(Nb2 O5 )z, and x, y, and z are respectively expressed in mol%, and stay in ranges as 59.5<=x<=61.8mol%, 19.1<=y<=20.6mol%, 19.1<=z<=20.1mol% (where, x+y+z=100mol%). 0.1mol or less (where, 0mol is not included) of titanium dioxide and 0.008mol or less (where, 0mol is not included) of magnesium oxide as accessory components are added to 1mol of this main component. Thereby, no-load Q can be made large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic for microwaves, has a large relative permittivity (ε _r ), has a large unloaded Q (Qu), and has a resonant frequency by changing the composition. Temperature coefficient (τ _f ) of 0ppm / ℃
It is designed so that it can be changed to any value centered on.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, Proceedings 2a of the 29th Joint Lecture on Applied Physics
-I-4P763 (1982) and the like. In recent years, a large number of dielectric resonators and filters for microwaves have been used in car phones, mobile phones, and receivers for satellite broadcasting.

Dielectric materials used for such applications have a large relative permittivity (ε _r ) and no-load Q (Qu),
Moreover, it is desired that the temperature coefficient (τ _f ) of the resonance frequency can be set to a positive or negative value centered on 0 ppm / ° C. by changing the composition. Conventional ceramics such as BaO—TiO ₂ System, ZrO ₂ -SnO-T
There was an iO ₂ system.

[0004]

However, in the above-mentioned conventional ceramics, when the temperature coefficient (τ _f ) of the resonance frequency shows a value near 0 ppm / ° C., the relative permittivity (ε _r ) value is satisfied. However, the unloaded Q (Qu) cannot be said to be sufficiently large, and as a result, when a device using these materials was incorporated, it could not be said to have sufficiently satisfactory characteristics as an apparatus. .

The temperature coefficient (τ _f ) of the resonance frequency is
It cannot be set to an arbitrary value, and due to the phase shift of other devices, a value other than 0 ppm / ° C (for example, + 6p
Even when required at pm / ° C, it could not be changed to the required value. The present invention has been made in order to improve these characteristics. Even when the composition is such that the relative dielectric constant (ε _r ) is large and the temperature coefficient (τ _f ) of the resonance frequency is around 0 ppm / ° C., no load Q ( It is an object of the present invention to provide a dielectric ceramic for microwaves having a large value of Qu).

[0006]

In order to achieve the above object, the microwave dielectric ceramics of 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 represented by (BaO) x · (CoO) y · (Nb ₂ O ₅ ) z, and x, y, and z are each mol%, and 59.5 ≦.
x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%,
19.1 ≦ z ≦ 20.1 mol% (however, x + y + z = 1
In the range of (00 mol%), and
Characterized by adding 1 mol or less (not including 0 mol) of titanium dioxide (TiO ₂ ) and 0.008 mol or less (not including 0 mol) of magnesium oxide (MgO). .

(2) 0.1 mol or less (not including 0 mol) of titanium dioxide (TiO ₂ ) and 0.008 mol or less (however, 0 Zirconium oxide (not containing moles) (ZrO ₂ )
Is added. (3) As a subcomponent, 0.
It is characterized in that 1 mol or less (not including 0 mol) of titanium dioxide (TiO ₂ ) and 0.008 mol or less (not including 0 mol) of zinc oxide (ZnO) are added. .

[0008]

[Action]

(1) According to the dielectric ceramics described in (1) above, the dielectric constant (ε _r ) and the unloaded Q (Qu) are large in the microwave region, and the temperature coefficient (τ _f ) of the resonance frequency is large.
Can be easily changed to any positive or negative value.

Further, the temperature coefficient (τ _f ) of the resonance frequency
Even when the composition is set to be near 0 ppm / ° C., the unloaded Q (Qu) has a large value. For this reason, it is effective for downsizing and low loss of microwave dielectric resonators and dielectric filters. Also, the temperature coefficient (τ _f ) of the resonance frequency is positive or
Since it can be easily changed to an arbitrary negative value, even if a temperature coefficient (τ _f ) of the resonance frequency is required to be a value other than 0 ppm / ° C due to the phase shift of other devices, etc. By changing the addition amounts of TiO ₂ and MgO, the temperature coefficient (τ _f ) of the resonance frequency can be set to any value from negative to positive.

(2) According to the dielectric ceramics described in (2) above, in addition to the effects of (1) and (1), the temperature coefficient (τ _f ) of the resonance frequency is positive or negative. Since it can be easily changed to a value, even if a temperature coefficient (τ _f ) of the resonance frequency is required to be a value other than 0 ppm / ° C. due to the phase shift of other devices, TiO ₂ and ZrO By changing the amount of addition of ₂ , it is possible to make the temperature coefficient (τ _f ) of the resonance frequency any value from negative to positive.

(3) According to the dielectric ceramics described in (3) above, in addition to the effect of and in (1) above, the temperature coefficient (τ _f ) of the resonance frequency can be any positive or negative value. Since it can be easily changed to a value, even if a temperature coefficient (τ _f ) of the resonance frequency is required to be a value other than 0 ppm / ° C. due to the phase shift of other devices, TiO ₂ and ZnO By changing the addition amount of
The temperature coefficient (τ _f ) of the resonance frequency can be set to any value from negative to positive.

[0012]

EXAMPLES Examples of the present invention will be described in detail below. A first embodiment of the present invention will be described. The starting material is chemically high-purity barium carbonate (BaCO ₃ ), cobalt oxide (CoO), niobium oxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), magnesium oxide (MgO).
Was used to accurately evaluate the composition as shown in Table 1. This was wet mixed with pure water for 20 hours using a plastic pot mill and zirconia balls. The mixture was dehydrated and dried, and then calcined in a magnesia container in air at a temperature of 1200 ° C. for 3 hours. The calcined product was wet pulverized in the same manner as in the mixing step, then dehydrated and dried to obtain fine particle powder. A binder was added to this powder and sufficiently mixed with the powder to obtain a granulated powder. A disk-shaped compact having a diameter of 20 mm and a thickness of 12 mm was produced from the granulated powder using a mold and a hydraulic press at a molding pressure of 1 to 3 t / cm ² .

The molded body thus obtained was placed in a magnesia container and fired in air at a temperature of 1500 ° C. for 5 hours to obtain a dielectric ceramic. After polishing this ceramic to a predetermined frequency, the dielectric characteristics were measured by the following method. The relative permittivity (ε _r ) and the unloaded Q (Qu) of the dielectric ceramics were measured by the Hacky-Coleman method. Further, the temperature coefficient (τ _f ) of the resonance frequency is based on the resonance frequency f (20) at 20 ° C. and the resonance frequencies f (−40) and f (80) at −40 ° C. and 80 ° C., respectively. The temperature difference ΔT (here, ΔT = 120 ° C. at −40 ° C. and 80 ° C.) was calculated 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.

[0015]

[Table 1]

In Table 1, sample N marked with *
o. Are comparative examples outside the scope of the present invention, and other sample Nos. Are within the scope of the embodiments of the present invention. According to the results of Table 1, when BaO is 59.5 mol% or less,
Sample No. 1, No. As shown in No. 15, when the unloaded Q (Qu) becomes small and exceeds 61.8 mol%, the sample No. 7
However, the no-load Q (Qu) becomes small as shown in FIG.

When CoO is 19.1 mol% or less, the sample No. When the unloaded Q (Qu) becomes small as in Example 7 and exceeds 20.6 mol%, the sample No. As in No. 15, the unloaded Q (Qu) is still small, which is inappropriate. Further, when the Nb ₂ O ₅ content was 19.1 mol% or less, the sample No. When the unloaded Q (Qu) becomes small as in Example 7 and exceeds 20.1 mol%, the sample No. As in No. 1, the unloaded Q (Qu) is still small, which is inappropriate.

Therefore, BaO is in the range of 59.5 to 61.8 mol%, CoO is in the range of 19.1 to 20.6 mol%, and Nb ₂ O ₅ is in the range of 19.1 to 20.1 mol%. The ranges are preferable ranges. Further, regarding TiO ₂ as a sub-component with respect to the main component, Sample No. 8 to 1
As shown in FIG. 2, the relative permittivity (ε _r ) tends to increase as the added amount increases, and is a sufficiently large value of 30 or more.

Further, the temperature coefficient (τ _f ) of the resonance frequency is
When the added amount of TiO ₂ is 0.005 mol (Sample No. 8)-
From 10.5 ppm / ° C., 0.5 mol (Sample No. 1
It increased to 59.8 ppm / ° C. in 2) as the amount of TiO ₂ added increased. Furthermore, the unloaded Q (Qu) is Ti
620 when the amount of O ₂ added is 0.005 mol (Sample No. 8)
It decreased from 0 to 3800 at 0.1 mol (Sample No. 11), and the addition amount of TiO ₂ was 0.5 mol (Sample N).
o. In the case of 12), it becomes as small as 1600, which is not suitable for the purpose of the present invention.

As described above, the addition amount of TiO ₂ is appropriately up to 0.1 mol. In addition, the sample No. 2 to sample No. As shown in Fig. 7, as the added amount increases, the relative dielectric constant (ε _r ) becomes
From 32.7 of O addition amount of 0.001 mol (Sample No. 2) to 3 of MgO addition amount of 0.008 mol (Sample No. 6)
Slightly reduced to 2.5, but added MgO 0.00
It is a sufficiently large value of 30 or more in the range of 1 mol to 0.008 mol. The temperature coefficient (τ _f ) of the resonance frequency is M
gO addition amount 0.001 mol (sample No. 2) -4.0
ppm / ° C. to 0.008 mol (Sample No. 6) −
Change to 6.8 ppm / ° C with small negative inclusion.

Further, the unloaded Q (Qu) was 0. 0 from the MgO addition amount of 5700 of 0.001 mol (sample No. 2).
It becomes as small as 008 mol (Sample No. 6) to 2500, and when it becomes 0.01 mol (Sample No. 7), it becomes as small as 500, which is not suitable for the purpose of the present invention. Thus, the appropriate amount of addition of MgO is 0.003 mol.

As described above, this (BaO) x. (Co
Dielectric ceramics obtained by adding TiO ₂ and MgO to O) y · (Nb ₂ O ₅ ) z have x = 60 mol%, y = 20.
Mol%, z = 20 mol% or so, in particular, x = 60.7 mol% with a slight excess of BaO, y = 19.6 mol%, z = 1
The largest unloaded Q (Qu) can be obtained in the composition in which 0.005 mol of TiO ₂ and 0.001 mol of MgO are added to 9.6 mol%. Further, by changing the addition amounts of TiO ₂ and MgO, the temperature coefficient (τ _f ) of the resonance frequency can be changed to any value from negative to positive.

Next, the second embodiment of the present invention will be described in detail. Chemically high-purity barium carbonate (BaCO ₃ ), cobalt oxide (CoO), niobium oxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), and zirconium oxide (ZrO ₂ ) are used as starting materials. The composition was accurately evaluated so that the composition shown in Table 2 was obtained. This was wet mixed with pure water for 20 hours using a plastic pot mill and zirconia balls. The mixture was dehydrated and dried, and then calcined in a magnesia container in air at a temperature of 1200 ° C. for 3 hours. The calcined product was wet pulverized in the same manner as in the mixing step, then dehydrated and dried to obtain fine particle powder. A binder was added to this powder and sufficiently mixed with the powder to obtain a granulated powder. A disk-shaped compact having a diameter of 20 mm and a thickness of 12 mm was produced from the granulated powder using a mold and a hydraulic press at a molding pressure of 1 to 3 t / cm ² .

The molded body thus obtained was placed in a magnesia container and fired in air at a temperature of 1500 ° C. for 5 hours to obtain a dielectric ceramic. After polishing this ceramic to a predetermined frequency, the dielectric characteristics were measured by the following method. The relative permittivity (ε _r ) and the unloaded Q (Qu) of the dielectric ceramics were measured by the Hacky-Coleman method. Further, the temperature coefficient (τ _f ) of the resonance frequency is based on the resonance frequency f (20) at 20 ° C. and the resonance frequencies f (−40) and f (80) at −40 ° C. and 80 ° C., respectively. It was determined from the temperature difference ΔT (here, ΔT = 120 ° C. at −40 ° C. and 80 ° C.) according to the following equation (2). The measurement frequency in these measurements was about 5 GHz.

Τ _f = {f (80) −f (40)} / {f (20) × 120} (2) Table 2 shows the measurement results of the dielectric properties of each composition.

[0026]

[Table 2]

In Table 2, sample N marked with *
o. Is a comparative example outside the scope of the present invention, and other sample Nos. Are within the scope of the embodiments of the present invention. According to the results of Table 2, regarding the composition of the main component, BaO was 59.5.
When it is less than mol% (Sample No. 10), no load Q (Q
u) becomes small and exceeds 61.8 mol% (Sample N
o. 2) It is also unsuitable because the unloaded Q (Qu) is small.

Further, when CoO is less than 19.1 mol% (Sample No. 2), the unloaded Q (Qu) becomes small, and when it exceeds 20.6 mol% (Sample No. 10), it is also completely absent. The load Q (Qu) is small and unsuitable. Furthermore, when Nb ₂ O ₅ is less than 19.1 mol (Sample N
o. 2), unloaded Q (Qu) becomes small, and when it exceeds 20.1 mol% (Sample No. 9), unloaded Q (Q)
u) is small and unsuitable.

Therefore, BaO is in the range of 59.5 to 61.8 mol%, CoO is in the range of 19.1 to 20.6 mol%, and Nb ₂ O ₅ is in the range of 19.1 to 20.1 mol%. The ranges are preferable ranges. Where BaO, Co
The total of the mol% of C and Nb ₂ O ₅ is 100 mol%. Further, regarding TiO ₂ as a sub-component with respect to the main component, Sample No. As shown in 16 to 19, as the added amount increases, the relative dielectric constant (ε _r ) shows an increasing tendency,
It is a sufficiently large value of 30 or more. Moreover, the temperature coefficient (τ _f ) of the resonance frequency is from 0.8 ppm / ° C. when the added amount of TiO ₂ is 0.005 mol (Sample No. 16) to 0.
The value increases to 46.0 ppm / ° C. at 5 mol (Sample No. 19) with an increase in the amount of TiO ₂ added.

Further, the unloaded Q (Qu) decreases from 6800 when the amount of TiO ₂ added is 0.005 mol (Sample No. 16) to 3400 when 0.1 mol (Sample No. 18), The amount of TiO ₂ added is 0.5 mol (Sample No. 1
When it becomes 9), it becomes as small as 2000, which is not suitable for the purpose of the present invention. Thus, the amount of TiO ₂ added is
Up to 0.1 mol is suitable.

Further, Zr as an accessory component to the main component
O ₂ is the sample No. 11 to Sample No. As shown in 14, the relative dielectric constant (ε _r ) does not fluctuate significantly, and is a sufficiently large value of 30 or more in the range of 0.001 mol to 0.01 mol of ZrO ₂ addition. Further, regarding the temperature coefficient (τ _f ) of the resonance frequency, the added amount of ZrO ₂ is 0.0
01 mol (Sample No. 11) of 0.5 ppm / ° C. to 0.008 mol (Sample No. 14) of 2.7 ppm / ° C.
It increases as the amount of ZrO ₂ added increases.

Further, the unloaded Q (Qu) was 6500 with the ZrO ₂ addition amount of 0.001 mol (Sample No. 11).
It decreased to 0.008 mol (Sample No. 14) to 4200, and became 0.01 mol (Sample No. 15) to 10
00, which is too small to meet the purpose of the present invention. Thus, the ZrO ₂ addition amount is appropriately up to 0.008 mol.

As described above, this (BaO) x. (Co
O) y ・ (Nb₂O_Five) TiO in z ₂And ZrO₂Add
The dielectric ceramics produced were x = 60 mol% and y = 20.
Mol% and z = 20 mol% or so with respect to 1 mol of the main component
TiO₂0.005 mol, ZrO₂0.002 mol
The highest unloaded Q (Qu) in the added composition
Obtainable. Also, TiO₂And ZrO₂Addition of
By changing the amount, the temperature coefficient (τ_f)
Can be changed to any value from negative to positive.

In this embodiment, the characteristics are measured by 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 diameter, 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, the third embodiment of the present invention will be described in detail.

Chemically high-purity barium carbonate (BaCO ₃ ), cobalt oxide (CoO), niobium oxide (Nb ₂ O ₅ ), titanium dioxide (TiO ₂ ), and zinc oxide (ZnO) are used as starting materials. Then, the composition was accurately evaluated so that the composition shown in Table 3 was obtained. This was wet mixed with pure water for 20 hours using a plastic pot mill and zirconia balls. The mixture was dehydrated and dried, and then calcined in a magnesia container in air at a temperature of 1200 ° C. for 3 hours. The calcined product was wet pulverized in the same manner as in the mixing step, then dehydrated and dried to obtain fine particle powder. A binder was added to this powder and sufficiently mixed with the powder to obtain a granulated powder.
This granulated powder is molded with a mold and a hydraulic press at a molding pressure of 1 to 3.
A disk-shaped compact having a diameter of 20 mm and a thickness of 12 mm at t / cm ² was produced.

The molded body thus obtained was placed in a magnesia container and fired in air at a temperature of 1500 ° C. for 5 hours to obtain a dielectric ceramic. After polishing this ceramic to a predetermined frequency, the dielectric characteristics were measured by the following method. The relative permittivity (ε _r ) and the unloaded Q (Qu) of the dielectric ceramics were measured by the Hacky-Coleman method. Further, the temperature coefficient (τ _f ) of the resonance frequency is based on the resonance frequency f (20) at 20 ° C. and the resonance frequencies f (−40) and f (80) at −40 ° C. and 80 ° C., respectively. The temperature difference ΔT (here, ΔT = 120 ° C. at −40 ° C. and 80 ° C.) was calculated according to the following equation (3). The measurement frequency in these measurements was about 5 GHz.

Τ _f = {f (80) −f (40)} / {f (20) × 120} (3) Table 3 shows the measurement results of the dielectric properties of each composition.

[0038]

[Table 3]

In Table 3, sample N marked with *
o. Is a comparative example outside the scope of the present invention, and other sample Nos. Are within the scope of the embodiments of the present invention. According to the result of Table 3, when BaO is 59.5 mol% or less, the sample No. 1, No. As shown in No. 15, when the unloaded Q (Qu) becomes small and exceeds 61.8 mol%, the sample No. As shown in No. 7, the unloaded Q (Qu) is still small, which is inappropriate.

When the CoO content was 19.1 mol% or less, the sample No. When the unloaded Q (Qu) becomes small as in Example 7 and exceeds 20.6 mol%, the sample No. As in No. 15, the unloaded Q (Qu) is still small, which is inappropriate. Further, when the Nb ₂ O ₅ content was 19.1 mol% or less, the sample No. When the unloaded Q (Qu) becomes small as in Example 7 and exceeds 20.1 mol%, the sample No. As in No. 1, the unloaded Q (Qu) is still small, which is inappropriate.

Therefore, BaO is in the range of 59.5 to 61.8 mol%, CoO is in the range of 19.1 to 20.6 mol%, and Nb ₂ O ₅ is in the range of 19.1 to 20.1 mol%. The ranges are preferable ranges. Further, regarding TiO ₂ as a sub-component with respect to the main component, Sample No. 8 to N
o. As shown in 12, as the added amount increases, the relative permittivity (ε _r ) tends to increase, which is a sufficiently large value of 30 or more. Also, the temperature coefficient (τ _f ) of the resonance frequency is
When the added amount of TiO ₂ is 0.005 mol (Sample No. 8)-
From 9.4 ppm / ° C, 0.5 mol (Sample No. 12)
60.5 ppm / ° C. and increases with an increase in the amount of TiO ₂ added.

Further, the unloaded Q (Qu) was calculated from 6800 when the added amount of TiO ₂ was 0.005 mol (sample No. 8),
It decreased to 3800 at 0.1 mol (Sample No. 11), and the addition amount of TiO ₂ was 0.5 mol (Sample No. 12).
Then, it becomes as small as 2000, which is not suitable for the purpose of the present invention. Thus, the amount of TiO ₂ added is 0.1
Up to moles are suitable.

In addition, Zn as an accessory component to the main component
O is the sample No. 2 to sample No. 7, the relative dielectric constant (ε _r ) does not change significantly, and is a sufficiently large value of 30 or more in the range of 0.001 mol to 0.008 mol of ZnO added. Also, the temperature coefficient of resonance frequency (τ
_f ) is 0.001 mol of ZnO added (sample N
o. It changes from -2.2 ppm / ° C of 2) to -6.8 ppm / ° C of 0.008 mol (Sample No. 6) with a small negative inclusion.

Further, the unloaded Q (Qu) was 0. 0 from 0700 of ZnO addition amount of 5700 (sample No. 2).
It becomes as small as 008 mol (Sample No. 6) to 3300, and when it becomes 0.01 mol (Sample No. 7), it becomes as small as 600, which is not suitable for the purpose of the present invention. As described above, the appropriate amount of ZnO added is 0.008 mol.

As described above, this (BaO) x. (C
The dielectric ceramics obtained by adding TiO ₂ and ZnO to oO) y · (Nb ₂ O ₅ ) z have x = 60 mol%, y = 20.
Mol%, z = 20 mol% or so, especially x = 60.7 mol% with a slight excess of BaO, y = 19.6 mol%, z = 19.
0.005 mol of TiO ₂ and 0.0 of ZnO in 6 mol%
The largest unloaded Q (Q
u) can be obtained, and the temperature coefficient (τ _f ) of the resonance frequency can be changed by changing the addition amounts of TiO ₂ and ZnO.
Can be changed to any value from negative to positive.

It should be noted that the present invention is not limited to the above embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0047]

As described in detail above, according to the present invention, the following effects can be achieved. (1) According to the invention of claim 1, the relative dielectric constant (ε _r ) and the no-load Q (Qu) are large in the microwave region, and the temperature coefficient (τ _f ) of the resonance frequency is large.
Can be easily changed to any positive or negative value.

Further, the temperature coefficient (τ _f ) of the resonance frequency
Even when the composition is set to be near 0 ppm / ° C., the unloaded Q (Qu) has a large value. For this reason, it is effective for downsizing and low loss of microwave dielectric resonators and dielectric filters. Also, the temperature coefficient (τ _f ) of the resonance frequency is positive or
Since it can be easily changed to an arbitrary negative value, even if a temperature coefficient (τ _f ) of the resonance frequency is required to be a value other than 0 ppm / ° C due to the phase shift of other devices, etc. By changing the addition amounts of TiO ₂ and MgO, the temperature coefficient (τ _f ) of the resonance frequency can be set to any value from negative to positive.

(2) According to the invention of claim 2, in addition to the effect of and of (1) above, the temperature coefficient (τ _f ) of the resonance frequency can be easily set to a positive or negative arbitrary value. The temperature coefficient (τ _f ) of the resonance frequency is 0p due to the phase shift of other devices.
Even if a value other than pm / ° C is required, the temperature coefficient (τ _f ) of the resonance frequency can be changed from negative to positive by changing the addition amount of TiO ₂ and ZrO _2. is there.

(3) According to the invention of claim 3, in addition to the effect of and of (1), the temperature coefficient (τ _f ) of the resonance frequency can be easily set to a positive or negative arbitrary value. The temperature coefficient (τ _f ) of the resonance frequency is 0p due to the phase shift of other devices.
Even when a value other than pm / ° 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 addition amounts of TiO ₂ and ZnO. .

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideki Ono 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (3)

[Claims] 1. Barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ), the composition formula of the main component is (BaO) x. (CoO) y. (Nb ₂ O _5). ) Z, where x, y, and z are each mol%, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.1 Mol% (however, x + y + z = 1
The amount of titanium dioxide (TiO 2) is 0.1 mol or less (excluding 0 mol) as an auxiliary component with respect to 1 mol of the main component.
₂ ) and 0.008 mol or less (excluding 0 mol)
2. A dielectric ceramic for microwaves, characterized in that the magnesium oxide (MgO) is added. 2. Barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ), whose composition formula is (BaO) x. (CoO) y. (Nb ₂ O _5). ) Z, where x, y, and z are each mol%, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.1 Mol% (however, x + y + z = 1
The amount of titanium dioxide (TiO 2) is 0.1 mol or less (excluding 0 mol) as an auxiliary component with respect to 1 mol of the main component.
₂ ) and 0.008 mol or less (excluding 0 mol)
Zirconium oxide (ZrO ₂ ) is added to the dielectric ceramics for microwaves. 3. Barium oxide (BaO), cobalt oxide (CoO), and niobium oxide (Nb ₂ O ₅ ), whose composition formula is (BaO) x. (CoO) y. (Nb ₂ O _5). ) Z, where x, y, and z are each mol%, 59.5 ≦ x ≦ 61.8 mol%, 19.1 ≦ y ≦ 20.6 mol%, 19.1 ≦ z ≦ 20.1 Mol% (however, x + y + z = 1
The amount of titanium dioxide (TiO 2) is 0.1 mol or less (excluding 0 mol) as an auxiliary component with respect to 1 mol of the main component.
₂ ) and 0.008 mol or less (excluding 0 mol)
2. A dielectric ceramic for microwaves, characterized in that the above zinc oxide (ZnO) is added.