JP3414207B2 - Sorting method of dielectric porcelain - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of selecting a dielectric ceramic used in a high frequency range such as microwaves and millimeter waves.

[0002]

2. Description of the Related Art In recent years, along with the increase in communication using electromagnetic waves in the microwave region such as car phones, mobile phones, satellite broadcasting, etc., miniaturization of dielectric parts such as filter elements and resonators that compose the equipment Is required. In order to reduce the size of such a dielectric component, in the dielectric ceramic, the relative dielectric constant is high and the loss is low in the microwave region, that is, the no-load Q value is high, and the temperature change of the resonance frequency is small. It is important that it is small, that is, the change in dielectric constant with temperature is small.

On the other hand, attempts have been made to miniaturize and enhance the functions of parts such as a resonator by forming a conductor and a dielectric ceramic in a laminated structure. However, when used in a high frequency region such as microwave, a conductor having high conductivity is required, and Cu, Au, Ag or their alloys must be used. Moreover, when using a laminated structure,
Since it is necessary to simultaneously fire the dielectric ceramic material and the conductor metal, a firing condition that the conductor metal does not melt and does not oxidize, that is, a dielectric ceramic that is densely sintered at a low temperature of 1050 ° C. or lower is required. .

Bi satisfying these conditions
The O3 _{/ 2} -CaO-NbO5 _{/ 2} system is disclosed in JP-A-5-225826.
It is disclosed in the publication. This dielectric ceramic has both a high relative permittivity and a no-load Q value, a small temperature coefficient of resonance frequency, and is capable of low temperature sintering.

[0005]

In general, such a dielectric ceramic is provided with stable characteristics without variations in characteristics such as sintering density, relative permittivity and unloaded Q value. Required to be manufactured.

Therefore, an object of the present invention is to provide a dense dielectric porcelain having both a high relative permittivity and a no-load Q value.

[0007]

In order to achieve this object, a method of selecting a dielectric ceramic according to the present invention is a bismuth oxide,
In the measurement by X-ray diffraction of the dielectric porcelain mainly containing calcium oxide and niobium oxide, the main peak intensity of the different phase is 10 with respect to the main peak intensity of the dielectric porcelain.
%, The dielectric constant and the unloaded Q value are both high, and a dense dielectric ceramic can be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is the measurement by X-ray diffraction of a dielectric ceramic mainly containing bismuth oxide, calcium oxide and niobium oxide,
This is a method for selecting a dielectric ceramic in which a main peak intensity of a different phase with respect to the main peak intensity of the dielectric ceramic is less than 10%, which is a good product, and has a high relative permittivity and a high no-load Q value, and a dense dielectric ceramic. Is obtained.

The invention according to claim 2 is a bismuth oxide,
When the calcined product of the starting material of the dielectric ceramic containing calcium oxide and niobium oxide as the main components is measured by X-ray diffraction, the main peak intensity of the different phase is less than 50% with respect to the main peak intensity of the calcined product, and it is regarded as a good product. This is a method for selecting dielectric porcelain, and it is possible to obtain a dense dielectric porcelain having a high relative permittivity and a high unloaded Q value.

FIG. 1 shows an embodiment of the present invention.
4 to FIG. (Embodiment 1) FIGS. 1 and 2 show the results of X-ray diffraction for a dielectric ceramic after main firing in the present embodiment. In FIG. 1, only the peak of the target dielectric ceramic is shown. This is the case where no peak is observed, and a peak of a different phase as shown by a mark in FIG. 2 is observed.

First, as a starting material, high-purity Bi ₂ O ₃ ,
Using CaCO ₃ and Nb ₂ O ₅ , xBiO _3/2 -yCaO-
When expressed as zNbO _5/2 , x = 0.47, y = 0.2
It was weighed so that the composition would be 1, z = 0.32. These powders were placed in a polyethylene ball mill, stabilized zirconia boulders and pure water were added and wet mixed for 15 hours. Put the resulting mixed powder in a container made of alumina. 800
It was calcined at ℃ for 2 hours. The calcined powder was put in the ball mill, and boulders made of stabilized zirconia and pure water were added, and the mixture was wet pulverized for 15 hours to obtain a raw material powder.

To this raw material powder, 5 wt% of a 5% aqueous solution of polyvinyl alcohol was added as a binder, and the mixture was granulated.
After the particles were sized through a mesh sieve, they were molded into a columnar shape having a diameter of 13 mm and a thickness of 5 mm at 100 MPa. The obtained molded body is put into a container made of magnesia, heated at 650 ° C. for 2 hours to incinerate the binder, and then 800 to 1050 ° C.
And sintered for 2 hours to obtain a sintered body.

The density of the obtained sintered body was measured by the Archimedes method. Then, both surfaces of the obtained sintered body, which was fired at a temperature at which the density became maximum, were polished, and the dielectric property by microwave was measured. The dielectric resonance method is used for the measurement, and the relative permittivity (hereinafter referred to as ε _r ),
An unloaded Q value (hereinafter referred to as Q value) and a temperature coefficient of resonance frequency (hereinafter referred to as τ _f ) were calculated. In the measurement of ε _r and Q value, the resonance frequency was 3 to 5 GHz. τ _f is -2
It measured in the range of 5-85 degreeC. Ten measurement samples were prepared and the characteristics were evaluated. The results are shown in (Table 1).

[0014]

[Table 1]

In Table 1, those marked with * are comparative examples outside the claims of the present invention. As is clear from this (Table 1), according to the present embodiment, in the sample having the different phase peak intensity of less than 10%, the sintered density is 6.96 g /
A sintered body having stable characteristics such as cm ³ or more, ε _r of 50 or more, and Q value of 400 or more is obtained. In particular, when no peaks of different phases are seen as in FIG. 1 (Sample Nos. 4, 5, 6), the relative permittivity and the unloaded Q value are 50 or more and 500, respectively.
The above and high values are sufficiently stable. Moreover, when a peak of a different phase is observed as shown in FIG.
% Or more (Sample No. 1), ε _r and Q value sharply decrease and sufficient performance as a microwave dielectric cannot be obtained.

The sintered density, relative permittivity, and unloaded Q value become smaller according to the size of the peak of the different phase, and further the dispersion of each characteristic becomes large. Since it is not possible to obtain a dielectric porcelain having only this different phase, the density, relative permittivity and unloaded Q value peculiar to the different phase are not known, but if this different phase exists in the finally obtained dielectric porcelain, it will not burn. Consolidation density,
The relative permittivity and the no-load Q value decrease, and the characteristic variation increases.

In the present embodiment, the X of the dielectric porcelain is
When the main peak intensity of the dielectric ceramics measured by line diffraction is less than 10% of the main peak intensity of the different phase remaining in the dielectric ceramics after firing, it is regarded as a good product. It is possible to stably obtain a dielectric ceramic with a high unloaded Q value, a high density, and a small variation.

Of course, it is more preferable that no heterogeneous phase remains. (Embodiment 2) FIGS. 3 and 4 show the results of X-ray diffraction of the powder after calcination according to the present embodiment. In FIG. 3, the peak of the target dielectric ceramic is the main. This is the case and Fig. 4
In this case, the peaks of different phases as indicated by the triangle mark are mainly observed.

High-purity Bi ₂ O ₃ , CaC as a starting material
Using O ₃ and Nb ₂ O ₅ , xBiO _3/2 -yCaO-zNb
When expressed as O _5/2 , x = 0.46, y = 0.21, z
The composition was weighed so that the composition was 0.33. These powders were placed in a polyethylene ball mill, stabilized zirconia boulders and pure water were added and wet mixed for 15 hours.
The obtained mixed powder is put in a container made of alumina and 600 to 80
It was calcined at 0 ° C. for 2 hours. The calcined powder was put in the ball mill, and boulders made of stabilized zirconia and pure water were added, and the mixture was wet pulverized for 15 hours to obtain a raw material powder.

To this raw material powder, 5 wt% of a 5% aqueous solution of polyvinyl alcohol was added as a binder, and the mixture was granulated.
After the particles were sized through a mesh sieve, they were molded into a columnar shape having a diameter of 13 mm and a thickness of 5 mm at 100 MPa. The obtained molded body was placed in a magnesia container, heated at 650 ° C. for 2 hours to incinerate the binder, and then baked at 900 ° C. for 2 hours to obtain a dielectric ceramic.

The obtained dielectric ceramic was measured and evaluated by the same method as in the first embodiment. The results are shown in (Table 2).

[0022]

[Table 2]

In Table 2, those marked with * are comparative examples outside the claims of the present invention. As is clear from this (Table 2), according to the present embodiment, as shown in FIG. 3, samples 9 and 10 having small different phase peaks, that is, the different phase peak intensity in the calcined powder are less than 50% are used. When firing the dielectric ceramic, almost no heterogeneous phase remains in the obtained dielectric ceramic, the sintering density is 6.96 g / cm ³ or more, ε _r is 50 or more, and the Q value is 400 or more. Thus, a dielectric ceramic having stable characteristics can be obtained. On the other hand, when a large peak of different phase is seen as shown in FIG. 4, that is, when the peak intensity of the different phase is 50% or more, the different phase remains in the obtained dielectric ceramic, and ε _r and Q value are rapidly decreased. Sufficient performance cannot be obtained as a microwave dielectric. Furthermore, the variation of each characteristic becomes large.

In the present embodiment, the main peak intensity of the different phase may be set to less than 50% with respect to the main peak intensity of the dielectric porcelain by measurement by X-ray diffraction of the calcined product, but it is 30%. By setting it to be less than 1, the dielectric constant and the unloaded Q value are both high, and moreover, a dense and stable dielectric ceramic can be stably obtained. More preferably, the main peak intensity of the different phase is less than 10% with respect to the main peak intensity of the dielectric ceramic.

In the first and second embodiments, only one example of the raw material composition is shown, but xBiO _3/2 −
When expressed as yCaO-zNbO _5/2 , 0.43 ≦ x ≦
0.55, 0.16 ≦ y ≦ 0.24, 0.28 ≦ z ≦
The same effect can be obtained if the composition is in the range of 0.36 (however, x + y + z = 1.0).

Further, as the dielectric porcelain material, only the main component material which becomes bismuth oxide, calcium oxide and niobium oxide after firing was used, but copper oxide or the like is used as an auxiliary component in order to promote low temperature sintering. In this case, the same effect can be obtained.

Further, the example in which the firing temperature and the calcination temperature are changed has been described, but the remaining amount of the different phase is changed by changing other conditions such as mixing conditions, calcination time, crushed particle size, and firing time. Also in, the same effect can be obtained.

[0028]

As described above, according to the present invention, a dense dielectric ceramic having a relative permittivity of 50 or more and an unloaded Q value of 300 or more can be stably obtained.

Further, by applying this dielectric ceramic, it is possible to stably provide a small-sized and high-performance laminated dielectric component which can be used in a high frequency region using a conductor having a high conductivity, and particularly a small resonance. Since the system can be configured, it largely contributes to downsizing of communication devices such as car phones and mobile phones that use electromagnetic waves in the microwave range.

[Brief description of drawings]

FIG. 1 is a characteristic curve diagram of X-ray diffraction of a dielectric ceramic after main firing according to a first embodiment of the present invention.

FIG. 2 is a characteristic curve diagram of X-ray diffraction of the dielectric ceramic after main firing according to the first embodiment of the present invention.

FIG. 3 is an X of the powder after calcination according to the second embodiment of the present invention.
Characteristic diagram of line diffraction

FIG. 4 is an X of the powder after calcination according to the second embodiment of the present invention.
Characteristic diagram of line diffraction

Claims (2)

(57) [Claims] 1. A measurement of a dielectric porcelain containing bismuth oxide, calcium oxide and niobium oxide as main components by X-ray diffraction, in which the main peak intensity of the different phase is less than 10% of the main peak intensity of the dielectric porcelain. How to select good dielectric ceramics. 2. The main peak intensity of the different phase relative to the main peak intensity of the calcined product is 50 when measured by X-ray diffraction of the calcined product of the starting material of the dielectric ceramic mainly containing bismuth oxide, calcium oxide and niobium oxide. A method of selecting dielectric porcelain that is less than% good.