JP3113829B2 - Dielectric porcelain composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency dielectric ceramic structure, and more particularly, to a high-frequency dielectric ceramic having a large quality factor and a high dielectric constant, and capable of stabilizing by adjusting a temperature coefficient of a resonance frequency. It relates to a porcelain structure.

[0002]

2. Description of the Related Art Recently, a frequency band of 3 has been widely used for mobile communications such as wireless telephones and automobile telephones, satellite broadcasting and satellite communications.
Communication systems utilizing microwaves of 00 MHz to 300 GHz have been remarkably developed. Further, in order to put such new media into practical use, dielectric ceramics for high frequencies are actively applied to resonators, band-pass (or blocking) filters, microwave integrated circuits (MIC), and the like. Such a high-frequency dielectric used in a communication system is:
(1) The wavelength of the microwave in the dielectric is の of the dielectric constant
Since it is inversely proportional to the power, the dielectric constant is high when the component is miniaturized. (2) Since the dielectric loss is proportional to the frequency, the Q value (that is, the reciprocal of the dielectric loss) is large. Temperature coefficient of the resonant frequency should be small (W. Wersing's Electronic Ceramics
(Edited by BCH Steele), 67 page, Elsevier Sci. Pub, New York, USA (1991)). In addition, a high-frequency dielectric used in a communication system should have a small change with time, a high thermal conductivity, and a good mechanical strength.

At present, as a dielectric to be used, B
a (M ⁺² _1/3 M ⁺⁵ _2/3 ) O ₃ (M ⁺² = Mg, Zn; M ⁺⁵ = T
a, Nb), Ba ₂ Ti ₉ O ₂₀ and (Zr, Sn)
Although a TiO ₄ -based material can be used, such a dielectric has a low dielectric loss since the dielectric constant is 40 or less. In addition, BaO—Sn ₂ O ₃ —TiO ₂ , (Ba, P
b) O—Nd ₂ O ₃ —TiO ₂ system and (Pb, Ca) Z
An rO ₃ -based material can be used. Such a dielectric has a high dielectric constant of 80 or more, but also has a high dielectric loss (Qx
fo (GHz) <10,000) (the above-mentioned Worthing reference;
And J. Kato, JEE, Sep., 114-118 (1991)).

In general, a material having a high dielectric constant has a high dielectric loss and a high temperature coefficient of the resonance frequency due to a defect of a dipole inside the dielectric. Temperature coefficient must be stable. In the case of CaTiO ₃ , the dielectric constant is as high as about 170, but the temperature coefficient of the resonance frequency is also +800 ppm / ° C.
Has the problem of becoming expensive (Jpn. J. Appl. Phy
s., 33, 5463-65 (1994)).

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-frequency dielectric ceramic structure having a dielectric constant of 40 or more and a high dielectric loss. Another object of the present invention is to provide a high-frequency dielectric composition capable of adjusting a temperature coefficient of a resonance frequency.

[0006]

Means for Solving the Problems] like this, an object of the present _{invention, (1-x) CaTiO 3} -xCa (Al 1/2 Ta
_1/2 ) O ₃ is achieved by providing a dielectric ceramic porcelain composition for high frequency represented by the formula: where x is in the range 0.3 ≦ x ≦ 0.5.

That is, the present invention provides a dielectric ceramic structure having the following formula. (1-x) CaTiO ₃ -xCa (Al _1/2 Ta _1/2 ) O
₃ (however, the range of x is 0.3 ≦ x ≦ 0.5)

[0008] The dielectric composition is composed of CaTiO ₃ and C
a (Al _1/2 Ta _1/2 ) O ₃ is a perovskite-type solid solution whose main component is Ca
It changes according to the amount of (Al _1/2 Ta _1/2 ) O ₃ . That is, as the content of Ca (Al _1/2 Ta _1/2 ) O ₃ increases, the dielectric constant gradually decreases in the range of 170 to 25, but Qxfo (GH _Z ) increases, and the resonance frequency increases. Is gradually changed from + to-as shown in FIG.

In particular, when the Ca (Al _1/2 Ta _1/2 ) O ₃ content is sintered near the 0.46 molar ratio for 15 hours or more, the dielectric constant is 46.5 and Qxfo is 27,000 or more. An excellent dielectric ceramic product for microwaves having a temperature coefficient of resonance frequency of 0 ppm / ° C. can be manufactured. That is, C
The content of a (Al _1/2 Ta _1/2 ) O ₃ is 0.44 to
In the range of 0.48, an excellent dielectric ceramic product for microwaves having a temperature coefficient of resonance frequency (TCF) of -10 ppm / ° C to +10 ppm / ° C can be obtained.

The above-mentioned dielectric porcelain composition can be manufactured by performing a usual ceramic manufacturing process using, for example, CaCo ₃ , Al ₂ O ₃ , TiO ₂ and Ta ₂ O ₃ as starting materials. More specifically, C
Before using aCo ₃ , Al ₂ O ₃ , TiO ₂ and Ta ₂ O ₃ , they are first dried, then these samples are mixed at a predetermined formation ratio, and the mixed powder is sintered in the air, and then pulverized. Then, the powder is recalcined (Calcination) to synthesize a uniform solid solution having a perovskite structure. After the synthetic powder is pulverized well, an aqueous PVA solution is added as a molding additive, pressed into a cylindrical sample, sintered in the air, and then subjected to a heat treatment to remove an organic binder. .

The dielectric properties such as the dielectric constant Q value and the temperature coefficient of the resonance frequency of the sintered specimen can be measured by a known dielectric resonance technique. As a result of the measurement, the dielectric ceramic composition according to the present invention has a dielectric constant of 41.4 to 65.7,
Qxfo (GHz) is 12,000 to 27,300, and the temperature coefficient of resonance frequency (TCF) is in the range of −20 to +113.
ppm / ° C, the temperature coefficient is 0pp
Since it can be adjusted to m / ° C, it has been found that it can be used as a material for high frequency dielectric ceramic parts.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below unless departing from the scope of the claims.

[0013]

EXAMPLE: 99% pure CaCo ₃ , Ta ₂ O ₃ and 9
Before using 9.9% Al ₂ O ₃ , TiO ₂
After drying at a temperature of 0 ° C. for about 10 hours, these samples were mixed at the formation ratios shown in Table 1, and the mixed powder was air-dried in air for 1 hour.
After being calcined at a temperature of 200 ° C. for about 4 hours, it was pulverized, and recalcined again at a temperature of 1,450 ° C. for 3 hours to synthesize a solid solution having a perovskite structure.

[0014]

[Table 1]

After pulverizing the synthetic powder, a 5% PVA aqueous solution is added as a forming additive, and the diameter is 10 mm and the thickness is 5-6.
mm, and heat-treated at a temperature of 600 ° C for about 1 hour to remove the organic binder, and then heated to a temperature of 1,500 ° C in air. Sintered for 3 to 15 hours. After sintering, the specimen is 10 ~
It shrank by about 16%.

Both sides of the sintered specimen are polished paper (up to # 300)
After being polished well, the sample was put into a waveguide, and a dielectric constant, a Q value, and a temperature coefficient of a resonance frequency were measured by a dielectric resonance technique.
At this time, the measurement frequency was 5.5 to 7.1 GHz, and the measurement temperature range was -15 to 85 ° C. Table 1 shows the microwave dielectric properties of each specimen.

[0017]

As described above, in the porcelain composite of a high-frequency dielectric according to the present invention, a stable high-frequency dielectric having a high dielectric constant, a small dielectric loss, and a temperature coefficient of resonance frequency can be adjusted. There is an effect that a porcelain composite can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in a temperature coefficient of a resonance frequency according to a formation change of a dielectric according to the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sergey E. Kuchjeko, Moscow, Russia 115492, Berule Fskaya 5-2-348 (56) References JP-A-10-139552 (JP, A) Sergey Kyucheiko, et. al. "Microwave Dielectric Properties of CaTi03-Ca (Al1 / 2Ta1 / 2) 03 Ceramics", Journal of the American Ceramics Society, Vol. 79, pp. 79, pp. 27, October 27, 1996, Vol. (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. The general formula (1-x) CaTiO ₃ -xCa
(Al _1/2 Ta _1/2 ) O ₃ (where x is 0.3 ≦ x ≦ 0.5
The dielectric porcelain composition shown by this. 2. The dielectric porcelain composition according to claim 1, wherein x satisfies 0.44 ≦ x ≦ 0.48.