JPH0524914A - Microwave dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composition free from MgO, CaO, and TiO2 and also capable of approaching the value of tauf to zero or stably and arbitrarily controlling it to the desired values on the positive side and the negative side centering around zero as a center while maintaining epsilonr and Qu in the practical characteristics ranges by adjusting the mixing ratio of CaTiO3. CONSTITUTION:This microwave dielectric porcelain composition consists of a mixed crystal of MgTiO3 and CaTiO3 and is free from MgO, CaO, and TiO2 and in which, when the mixing ratio of the above-mentioned MgTiO3 and CaTiO3 is represented by expression (1-x)MgTiO3.xCaTiO3, (x) is in 0.03-0.07.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave dielectric porcelain composition, and more specifically, to a high temperature of unloaded Q (hereinafter simply referred to as "Q") while maintaining a temperature coefficient of resonance frequency ( (Hereinafter simply referred to as τf)), and by adjusting the mixing ratio of CaTiO ₃ , τf can be arbitrarily controlled to the plus side and the minus side around zero. The present invention relates to a body porcelain composition. The present invention provides a dielectric resonator, a microwave integrated circuit board,
It is used for impedance matching of various microwave circuits.

[0002]

2. Description of the Related Art Microwave dielectric porcelain compositions (hereinafter simply referred to as dielectric porcelain compositions) tend to increase in dielectric loss as the operating frequency becomes higher.
A dielectric ceramic composition having a large Qu in the micro frequency range is desired. As a conventional dielectric porcelain material, a dielectric porcelain composition having a crystal structure containing two phases of a perovskite phase and an ilmenite phase (Japanese Patent Laid-Open No. 2-129065),
A dielectric ceramic composition (Japanese Patent Laid-Open No. 52-118599) in which MgTiO ₃ and TiO ₂ contain a predetermined amount of CaTiO ₃ is known.

[0003]

However, the former dielectric ceramic composition contains a large amount of other components such as ZnO, and Q
u is not necessarily a large value either. The latter dielectric ceramic composition contains TiO ₂ as an essential component,
When the amount of O ₃ added is in the range of 3 to 10% by weight, τf greatly changes from +87 to -100, and there is a problem that it is difficult to adjust a small value near 0.

The present invention solves the above problems and does not contain MgO, CaO and TiO ₂ , and further Ca
By adjusting the mixing ratio of TiO ₃ , ε _f and Qu can be maintained within a practical characteristic range, and τ f can be brought close to zero, or can be arbitrarily and stabilized at desired values on the plus side and the minus side centered on zero. It is an object of the present invention to provide a dielectric porcelain composition that can be controlled by the above method.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies on a composition of a dielectric ceramic composition that brings τf close to zero while maintaining a high Qu. As a result, MgO, Ca
The inventors have found that this defect can be eliminated by not adding O and TiO ₂ and adjusting the mixing ratio of CaTiO ₃ , and have completed the present invention. That is, the dielectric porcelain composition of the first invention is made of MgTiO ₃ and Ca.
It consists of a mixed crystal of TiO ₃ , MgO, CaO and TiO _2.
Not contained, the mixing ratio of the MgTiO ₃ and the CaTiO _{3 are, (1-x) MgTiO 3} · xCaTiO 3
When expressed by the formula, x is 0.03 ≦ x ≦ 0.07. If the above x is smaller than 0.03, τf
Is a large negative value, and conversely, when it exceeds 0.07, τf has a large positive value, which is not preferable. Also,
In particular, when x is 0.04 ≦ x ≦ 0.07,
Qu is 5000 to 7000 and τf is -15 to +15 (p
pm / ° C.), and further excellent performance,
preferable. As the mixing ratio of CaTiO ₃ increases, τf tends from a negative value to a positive direction, ε _r increases, and Qu tends to decrease. Therefore, C
In the above-mentioned appropriate addition amount range of aTiO ₃ , these performances are well balanced.

[0006]

EXAMPLES The present invention will be specifically described below with reference to examples. 99.9% pure MgO powder, CaCO ₃ powder, T
Composition formula (1-x) MgT using iO ₂ powder as a starting material
iO ₃ · xCaTiO ₃ x is 0.93, 0.95,
A predetermined amount was weighed and mixed so that each composition was 0.97. Then, after dry-mixing and primary pulverization with a mixer, calcination was performed in the air atmosphere at a temperature of 1100 ° C. for 2 hours. Then, an appropriate amount of an organic binder and water were added to the calcined powder, after trituration with alumina balls 20 mm.phi, granulated by spray drying, at a press pressure of 1000 kg / cm ² by using the granulated material 19mmφ × 8m
It was formed into a disk shape of mt (thickness).

Next, this molded product was exposed to air in Tables 1 and 2
No. 1325 to 1425 ° C. for 4 hours, and finally both end faces are polished into a disk shape of about 16 mmφ × 6 mmt (thickness) to obtain dielectric sample No. It was set to 1-18. Then, for each sample, ε _r (relative permittivity), Qu and τ f, and the sintered density were measured by a parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MODE) or the like. still,
The resonance frequency is 4.5 GHz. The results are shown in Table 1 and FIGS. Also, as an example, 0.95M
The results of X-ray diffraction in the case of gTiO ₃ · 0.05CaTiO ₃ shown in FIG.

[0008]

[Table 1]

According to these results, (1-x) MgT
If the x of iO ₃ · xCaTiO ₃ is large, the Qu value tends to be small, but conversely, τf and ε _r tend to be large on the plus side. The sintered density does not change so much and is 3 or more in all cases. This tendency is the same regardless of the firing temperature. At a firing temperature of 1350 to 1425 ° C., τf is +1 when x is in the range of 0.03 to 0.07.
4 to -37, ε _r is 17 to 21, Qu is 3430 to 70
70 is preferable because it shows a practical characteristic range. Particularly, when x is in the range of 0.04 to 0.07, for example, when the firing temperature is 1375 ° C., as shown in FIGS.
f is −15.4 to +14.1, ε _r is 19.2 to 21.
2 and Qu are 5000 to 6350, showing a particularly excellent performance balance. Further, regarding τf, since the change rate is low, it is easy to adjust a small value of 0 approximation. On the other hand, when CaTiO ₃ is not included, the Qu value is large, but ε _r is small, and τ f is −25 to −44, which is extremely small on the minus side, which is not preferable. Further, as shown in FIG. 4 showing an example, the structure of the product of the present invention is
According to the analysis method based on the presence or absence of the X-ray diffraction peak, MgT
Consisting of iO ₃ and CaTiO ₃ , other components (MgO, C
aO, TiO ₂ ) are not contained.

The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention according to the purpose and application. That is,
Various calcination conditions such as the calcination temperature and the calcination conditions such as the calcination temperature can be selected.

[0011]

INDUSTRIAL APPLICABILITY As described above, the dielectric ceramic composition of the present invention maintains the high Qu and ε _r in the practical characteristic range, while adjusting the CaTiO ₃ mixing ratio,
It is possible to bring τf close to zero or to control it to a desired value on the plus side and the minus side centered around zero, and to adjust τf to around 0 stably. Therefore, the mixing ratio of CaTiO ₃ can be changed according to the purpose.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship of τf in a change of a firing temperature and a mixing ratio of MgTiO ₃ and CaTiO ₃ .

FIG. 2 is a graph showing the relationship between ε _r in the change of the firing temperature and the mixing ratio of MgTiO ₃ and CaTiO ₃ .

FIG. 3 is a graph showing a relationship of Qu in a change of a firing temperature and a mixing ratio of MgTiO ₃ and CaTiO ₃ .

FIG. 4 0.95MgTiO ₃ /0.05CaTiO ₃
It is a graph which shows the X-ray-diffraction result in the case of.

Claims (2)

[Claims] 1. A mixed crystal of MgTiO ₃ and CaTiO ₃ , containing no MgO, CaO and TiO ₂ , and the mixing ratio of MgTiO ₃ and CaTiO ₃ is
(1-x) When expressed by the formula of MgTiO ₃ · xCaTiO ₃ , x is 0.03 ≦ x ≦ 0.07. A microwave dielectric ceramic composition. 2. The above x is 0.03 ≦ x ≦ 0.07, and the unloaded Q (Qu) at 4.5 GHz is 5000 to 7
000, temperature coefficient (τf) of resonance frequency is -15 to +1
The microwave dielectric ceramic composition according to claim 1, wherein the microwave dielectric ceramic composition is 5 (ppm / ° C.).