JPH09208304A - Microwave dielectric ceramic composition and resonator with base using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a microwave dielectric ceramic composition excellent in characteristic such as Qu and τf free from color unevenness and spotting, when made into a product such as a resonator and to provide a resonator with a supporting base more improved especially in Qu using the composition. SOLUTION: This dielectric ceramic composition comprises a composition of the formula, xMgTiO3 .(1-x)CaTiO3 [0.925<=x<=0.940] as a main component, 0.05-0.5wt.%, especially 0.05-0.4wt.% of MnO2 and 1-6wt.%, especially 1-4wt.% of Nb2 O5 based on 100wt.% of the xMgTiO3 .(1-x)CaTiO3 . A resonator excellent in performances free from color unevenness, etc., can be obtained when a dielectric ceramic composition in which (x) is 0.930, MnO2 is about 0.1wt.% and Nb2 O5 is about 1.5wt.% is used and made into a resonator with a supporting based.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microwave dielectric ceramic composition (hereinafter referred to as a dielectric ceramic composition) and a resonator with a support using the same. More specifically, in terms of appearance, a dielectric ceramic composition capable of obtaining a product such as a resonator having a high commercial value without color unevenness or stains, and particularly, an unloaded Q (hereinafter, simply referred to as Qu) value is more preferable. The present invention relates to an improved resonator with a support. The dielectric ceramic composition of the present invention can be used as a dielectric resonator in a microwave region, a microwave integrated circuit substrate, an impedance matching member of various microwave circuits, and the like.

[0002]

2. Description of the Related Art Dielectric loss tends to increase in dielectric ceramic compositions as the operating frequency increases. Therefore, a dielectric ceramic composition having a large Qu in the micro frequency range is desired. Conventionally, as this type of dielectric porcelain composition, there is one having a crystal structure including two phases of a perovskite phase and an ilmenite phase (Japanese Patent Application Laid-Open No. 2-129065). Also, MgTiO ₃ and TiO ₂ containing a predetermined amount of CaTiO ₃ (Japanese Patent Laid-Open No. 52-1185).
No. 99) is also known.

However, in the former dielectric ceramic composition, N
Other components such as d ₂ O ₃ , La ₂ O ₃ , PbO, and ZnO are contained in a considerable amount, and Qu is not necessarily a large value. In the latter dielectric ceramic composition, TiO 2
₂ is included as an essential component, and the mixing amount of CaTiO ₃ is 3 to
In the range of 10% by weight, there is a problem that τ _f largely changes to the plus side and the minus side, and it is difficult to adjust it to a small value near 0.

In addition, MgTiO ₃ and a small amount of CaTiO ₃
It is also known that (a) and (b) are main components and a specific amount of Nb ₂ O ₅ is contained therein (JP-A-6-107457). In this dielectric ceramic composition, ε _r (dielectric constant) and Q
It is said that τ _f can be arbitrarily and stably adjusted within a narrow range centered on zero while maintaining u within a practical characteristic range. However, the dielectric porcelain composition having the above composition has a problem in that, for example, when it is formed into a resonator or the like, color unevenness, stains or the like occur in the product. Moreover, the color unevenness exists not only on the surface of the product but also inside. Therefore, it cannot be solved by post-treatment such as polishing.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a dielectric ceramic composition and a resonator with a support using the same. More specifically, in the case of producing a product such as a resonator, there is no problem in appearance such as color unevenness or stains, and Q
The present invention relates to a dielectric ceramic composition capable of adjusting τ _f in a narrow range near zero while maintaining u at a high value.

Further, the present invention relates to a resonator with a support base, which is composed of a resonator made of the above dielectric ceramic composition and a support base, has no color unevenness, and has improved Qu.
In the present invention, by using an appropriate amount of Nb ₂ O ₅ , it is possible to obtain a dielectric ceramic composition having high quality even when fired in a wide temperature range.

[0007]

The dielectric ceramic composition of the first invention is mainly composed of a composition represented by xMgTiO _3. (1-x) CaTiO ₃ [where 0.925 ≦ x ≦ 0.940]. And the above xMgTiO ₃ · (1-x) Ca
1 to 6 parts by weight of Nb _{2 with} respect to 100 parts by weight of TiO _3.
O ₅ and 0.05 to 0.5 parts by weight of MnO ₂ are additionally contained.

The resonator with a support base of the second invention is x
MgTiO ₃ · (1-x) CaTiO ₃ [however, 0.9
25 ≦ x ≦ 0.940] as a main component,
The above xMgTiO ₃ · (1-x) CaTiO ₃ 1
A resonator formed by firing a dielectric ceramic composition containing 1 to 6 parts by weight of Nb ₂ O ₅ and 0.05 to 0.35 parts by weight of MnO ₂ with respect to 00 parts by weight, and a support. It is characterized by being integrated with the stand.

In the first invention, when the content of "MnO ₂ " is less than 0.05% by weight, the color unevenness and stains of products such as resonators are sufficiently improved to the extent that they cannot be easily visually confirmed. Not done. Further, when the content is 0.5% by weight, color unevenness and the like are sufficiently solved.

When MnO ₂ is contained in an amount of more than 0.5% by weight, the product becomes a dark brown color and the appearance is not so preferable, and further, the Qu value is lowered or becomes unstable. There is. If the content of MnO ₂ is 0.05 to 0.4% by weight, particularly 0.05 to 0.3% by weight, problems such as color unevenness are sufficiently improved and other problems may occur. Nothing.

In the second invention, when the MnO ₂ content is less than the lower limit, the same problem as in the first invention occurs. Also,
When this content is 0.35% by weight, problems such as color unevenness and stains are sufficiently solved. When the content of MnO ₂ is more than 0.35% by weight, the improved Qu value is reduced again by the addition of MnO _2, and is even lower than that when MnO ₂ is not added.

The content of MnO ₂ is 0.05 to 0.3.
The amount by weight is more preferably about 0.05 to 0.25% by weight. When MnO ₂ is in this range, problems such as color unevenness are solved and Qu becomes a sufficiently high value. still,
In the second invention, a resonator with a support base having a Qu value of about 26500 to 30000 can be obtained depending on the contents of x, Nb ₂ O ₅ and MnO ₂ .

Most of the resonators made of ceramic are provided with a supporting base as in the second invention, and a finished product integrated with the supporting base is usually provided as a commercial product.
As the material forming the "support", a material having a dielectric constant lower than that of the dielectric ceramic composition used in the present invention can be used. For example, ceramics such as alumina and silica or various plastics can be used.

When the support is made of a ceramic molded product, the resonator with the support can be obtained by a general method such as a rubber press method. On the other hand, when the support base is made of plastic, the molded and fired resonator is bonded to the predetermined position of the support base by an adhesive that is usually used for this type of application, such as glass adhesive or resin adhesive. , Just fix it.

In the first and second inventions, x is 0.
When it is less than 925, τ _f becomes a large value on the plus side and Qu decreases. When x exceeds 0.940, τ _f has a large negative value. Further, if the above "Nb ₂ O ₅ " is less than 1% by weight, stable firing becomes difficult, especially when the firing temperature is low. Also, Nb ₂
When O ₅ exceeds 6% by weight, τ _f increases to the negative side.

By adding Nb ₂ O ₅ as described above, it is possible to produce a sintered body having stable performance and high sintering density even if it is fired in a wide temperature range. The addition amount of Nb ₂ O ₅ is particularly preferably 1 to 4% by weight, more preferably 1 to 2% by weight. When the amount added is in this range, it is possible to more stably fire and obtain a well-balanced and excellent performance dielectric ceramic composition.

In particular, x is around 0.930, Nb ₂ O ₅
When the addition amount of is about 1 to 2% by weight, 1300 to
Even when fired in a temperature range of about 1350 ° C., it is possible to stably obtain a dielectric ceramic composition having a high Qu, a narrow range of τ _f centered at zero, and an appropriate ε _r . In addition, as the content ratio of CaTiO ₃ increases,
τ _f tends from the negative value to the positive direction, and ε _r tends to increase, while Qu tends to decrease. Furthermore, when the amount of Nb ₂ O ₅ added is increased, Qu and ε _r
Does not change so much, but τ _f tends to decrease.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples. (1) Preparation of Cylindrical Specimen and Its Evaluation MgO powder (purity; 99.4%), CaCO ₃ powder (purity; 99%), TiO ₂ powder (purity; 99.98%),
Nb ₂ O ₅ powder (purity; 100%) and MnO ₂ powder (purity; 99.50%) were used as starting materials.

The composition formula 0.93MgTiO ₃ .0.
07CaTiO ₃ and 0.93Mg
When TiO ₃ .0.07CaTiO ₃ is 100% by weight, 1.5% by weight of Nb ₂ O ₅ and 0, 0.1, 0.
A predetermined amount (about 500 g as a total amount) was weighed and mixed so that the composition contained 2 and 0.5% by weight of MnO ₂ .

Each of these powders was mixed with a mixer for 20 to 3
After dry mixing for 0 minutes, primary pulverization was further performed. Then, the obtained powder was calcined at a temperature of 1100 ° C. for 2 hours in an air atmosphere. Then, an appropriate amount of an organic binder (29 g) and water (300 to 400 g) were added to this calcined powder, and a 20 mmφ alumina ball was used in a ball mill and pulverized at 90 rpm for 23 hours. Then, it is granulated by vacuum freeze-drying (about 0.4 Torr, 40 to 50 ° C., about 20 hours), and the granulated raw material is used for 100
19 mmφ (diameter) x 11 at a pressing pressure of 0 kg / cm ^2.
A columnar molded body of mmt (thickness) was obtained.

Next, the molded body was subjected to 500 atmosphere in the atmosphere.
Degreasing for 3 hours at a temperature of ℃, then 1250-140
It was calcined at a temperature of 0 ° C. for 4 hours. Then, the peripheral surface and both end surfaces of the obtained sintered body were polished to about 16 mmφ × 8 mmt.
It has a cylindrical shape of the size. Using this cylindrical sintered body as a sample, color unevenness, stains and the like on the surface were visually observed. In addition, the parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MOD
Qu was measured according to E).

As a result, when MnO ₂ is not added,
Although the test piece was slightly grayish white, annular color unevenness was clearly observed by visual observation, especially at the peripheral edges of both end surfaces. Also, both end surfaces of this sample were polished, but the same color unevenness could not be eliminated. From this, it can be inferred that the color unevenness is continuously present in the lengthwise direction of the cylindrical test piece.

MnO ₂ was added to 0.1, 0.2 and 0.5
The above-mentioned color unevenness, stains, etc. were not observed at all in each sample made of the dielectric porcelain composition contained by weight%. The color of each sample changed from cream to brown with an increase in MnO ₂ . On the other hand, the value of Qu is 4000 to 500
Although it varied in the range of about 0, there was no particular correlation with the content of MnO ₂ .

(2) Resonator with support base and its evaluation Four kinds of dielectric ceramic compositions having the same composition as in (1) above were used, and the resonator with support base 1 shown in FIG.
I got With respect to the resonator 1 with the support base, color unevenness and the like were observed in the same manner as (1) above.

The resonator 1 with the support base is housed inside the cylindrical metal case 2 and placed on the center of the bottom surface 2a of the cylindrical metal case 2 with the support base 1a side facing downward. Using the through hole provided in this central portion, the resonator 1 with a support base and the cylindrical metal case 2 were integrally fixed by a fastening member 3 such as a bolt and a nut. And T
The dimensions of each part are D = 80 mmφ and L = 7 so that the resonance frequency in E ₀₁ δ mode is 2000 MHz.
0 mm, d ₁ = 45 mmφ, d ₂ = 20 mmφ, l ₁ =
The Qu was measured by setting 25 mm and l ₂ = 15 mm.

As a result, the color unevenness and stain of the resonator were the same as those of the test piece of (1). Also, with respect to Qu, unlike the case of the sample of (1), MnO _{2 is} obviously used.
There was a correlation with the content of. That is, Qu without addition of MnO ₂ was 26450 (resonance frequency f ₀ = about 2).
On the other hand, when the content of MnO ₂ is 0.1% by weight, Qu is 27810 (f ₀ = about 2051).
It was considerably improved.

Further, when MnO ₂ is 0.2% by weight, Qu
Is 27440 (f ₀ = about 2052) and MnO ₂ is 0.
It is slightly lower than the case of 1% by weight. However, it is still found that the value is considerably higher than that in the case where MnO ₂ is not added. And the content of MnO ₂ is 0.5
In weight%, Qu is 25210 (f ₀ = about 2049).
When compared with the case where MnO ₂ is not contained, the value is considerably low. Therefore, even if the content of 0.5 wt% is not a problem for color unevenness, the result of Qu shows that Mn
The upper limit of the O ₂ content is 0.35% by weight.

It should be noted that the present invention is not limited to the specific embodiments described above, but can be variously modified within the scope of the present invention depending on the purpose and application. For example, various calcination conditions such as the calcination temperature and calcination conditions such as calcination temperature can be selected. Further, as the raw material to be CaO, peroxides, hydroxides, nitrates and the like can be used in addition to the above CaCO ₃ . Similarly, for other oxides, various compounds that can be converted into oxides by heating can be used.

[0029]

The dielectric porcelain composition of the first invention does not cause color unevenness or stains on products manufactured using the composition, such as resonators. Further, while keeping Qu and ε _{r of the} product within a practical range, τ _f can be controlled to a desired value close to zero on the plus side and the minus side around zero. Further, in the resonator with a support base according to the second aspect of the invention, not only there is no unevenness in color or stains as in the above,
By including an appropriate amount of MnO ₂ , Qu can be further improved, and a resonator with excellent performance can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state where a resonator with a support base of the present invention is housed and fixed in a cylindrical metal case.

[Explanation of symbols]

1; Resonator with support base, 1a; Support base, 2; Cylindrical metal case.

Claims (2)

[Claims] 1. xMgTiO _3. (1-x) CaTiO
₃ [however, 0.925 ≦ x ≦ 0.940] is the main component, and the above xMgTiO ₃ · (1-
x) Microwave dielectric ceramic composition characterized by containing 1 to 6 parts by weight of Nb ₂ O ₅ and 0.05 to 0.5 parts by weight of MnO ₂ with respect to 100 parts by weight of CaTiO _3. Stuff. 2. xMgTiO _3. (1-x) CaTiO
₃ [however, 0.925 ≦ x ≦ 0.940] is the main component, and the above xMgTiO ₃ · (1-
x) 1 to 6 parts by weight of Nb ₂ O ₅ and 0.05 to 0.35 parts by weight of MnO _{2 with} respect to 100 parts by weight of CaTiO _3.
A resonator with a support, wherein a resonator obtained by firing a microwave dielectric porcelain composition containing and added is integrated with a support.