JPH04141908A - dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a dielectric ceramic composition having high dielectric constant, low dielectric loss in a microwave region, and small temperature coefficient of the dielectric constant by specifying the composition of the dielectric ceramic composition comprised of lead oxide, calcium oxide, nickel oxide, magnesium oxide, and niobium oxide. CONSTITUTION:In a composition having a formula (Pb1-xCax)(Mg1/3Nb2/3)1-y(Ni1/3Nb2/3)yO3, x and y are respectively defined as 0.3<=x<=0.6, 0.0<y<1.0. In this case, in a solid solution of (PbCa)(Mg1/3Nb2/3)O3 and (PbCa)(Ni1/3Nb2/3) O3, that is (Pb1-xCax)(Mg1/3Nb2/3)1-y(Ni1/3Nb2/3)yO3, x and y are defined as 0.3<=x<=0.6, 0.0<y< 1.0, respectively. As a result, high dielectric constant, high Q value in a microwave region, and good temperature coefficient of the dielectric constant are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to dielectric ceramic compositions used in the microwave range.

Conventional technology In recent years, car phones, portable telephones, satellite broadcasting, etc.
BACKGROUND OF THE INVENTION As communication using electromagnetic waves in the microwave region progresses, there is a demand for smaller devices. For this purpose, the individual components that make up the equipment need to be miniaturized.

In these devices, dielectrics are incorporated into filter elements and oscillation elements as dielectric resonators. When using the same resonance mode, the size of a dielectric resonator is inversely proportional to the square root of the dielectric constant of the dielectric material. Therefore, to create a small dielectric resonator, it is necessary to use a material with a high dielectric constant. It becomes necessary. Other properties required of dielectrics include low loss in the microwave region, i.e., a high no-load Q value, and small temperature changes in the resonant frequency, i.e., small temperature changes in the dielectric constant. is required.

The dielectric material conventionally used in this field is Ba.
(Zn+7sTaxzs)0@, BaO-TiO2
Compositions of this type and compositions in which some of them are replaced with other elements have been known. All of these have a dielectric constant of about 30, which is too low to miniaturize the resonator. As a material with a higher dielectric constant, B a O-T
The i 02-5m20° material composition was published in JP-A-57-1.
This material composition is disclosed in Japanese Patent No. 5309.
It has a relative dielectric constant of about 0, a high no-load Q value of about 3000 at 2 to 4 GH2, and a small temperature coefficient of dielectric constant.

Problems to be Solved by the Invention However, with the above-mentioned conventional dielectric ceramic compositions, it is difficult to obtain a higher dielectric constant, a higher no-load Q value, and a smaller temperature coefficient to further downsize the resonator. However, the temperature coefficient of permittivity is generally negative as the permittivity increases, but P b Z
Some have positive values, such as rO8. Therefore, attempts have been made to reduce the temperature coefficient by combining materials with positive and negative values. +A with negative temperature coefficient
For example, TiO2 and 5rTiO8 are known, and the temperature coefficient τ of the resonance frequency is 500 ppm/'C or more. , and as a material with a positive temperature coefficient, P
As a material composition in which a lanthanide oxide is added to bO-ZrO2, there is Pl)0-T+)203-Zr02 disclosed in JP-A-61-156602, and the temperature coefficient of resonance frequency τ, j,! 11000pp/'
It is about C. These materials have a large relative dielectric constant of 100 or more, and although they tend to be used to make resonators smaller, they have the problem of exhibiting a large temperature change in the resonant frequency.

The present invention solves the above-mentioned conventional problems, and provides an excellent dielectric ceramic composition that has a high dielectric constant, low loss in the microwave region, and a small rate of change in dielectric constant with temperature. . To aim for something.

Means for Solving the Problems In order to achieve the objects described in the present invention, (Pb+-xc
aj(Mg+zJbzz3)+-y(Ni+zJbz/
s) In the compositional formula represented by y OH, X and y
0.3≦X≦0.6 o, o<y<x.

The range shall be as follows.

According to the present invention, the magnesium-obic acid carrier carnoum (P b Ca ) (M g y, N b
2/z>08 and lead calcium nickel niobate (PbC
a) Solid solution of (N r l/3 N b zys ) 03, i.e. (Pbl-,, Cax) (ligi/Jb
z/z)+-y (Ni+zJbzzi), 03 d, X is 0.3≦X≦0.6, y is 0.0<y<
1. , 0, it is possible to achieve a high dielectric constant, a high Q value in the microwave region, and excellent temperature characteristics.

Example Next, one embodiment of the present invention will be described.

Mg0N i O with high chemical purity as a starting material
. These powders are made of polyethylene
9. Add stabilized zirconia cobbles and pure water and mix for 17 hours. After mixing, dry the slurry 5, put it in an alumina crucible and transfer to 750 and 850.
Calcinate for 2 hours in a factory.

The calcined body is coarsely crushed using a grinder, then crushed for 17 hours using the aforementioned Pormill, and dried to obtain a raw material powder. After adding 6% by weight of a 5% aqueous solution of polyvinyl alcohol as a binder to this powder and mixing it, it is passed through a 32mm sieve to form a powder, and molded into a cylinder with a diameter of 13N and a thickness of about 5m under a pressure of 100Mpδ. . The molded body is 600"
After incinerating the binder at C for 2 hours, the binder was placed in a magnesia container, and the calcined powder of the composition of this example was placed around it to prevent the evaporation of I) b O. Baking is performed by holding at 1100 to 1400°C for 2 hours depending on each composition while protecting the composition. The resonance frequency and no-load Q value of the obtained sintered body were determined by measurement using the dielectric resonator method.

In addition, the relative dielectric constant was calculated from the dimensions of the sintered body and the resonance frequency. The resonant frequency was 2-4 GHz. Also = -25°
Measure the resonance frequency at C and 85°C, 20
The temperature change rate (τ,) was calculated based on the value of ° [:].8 These results are shown in the table below. As is clear, the ceramic composition included in the claims has a high dielectric constant of 60 or more, a no-load Q value of 800 or more, and a temperature change rate of the resonant frequency ( The absolute value of τt) is 1100 pp/'C or less. A composition in which the value of X is less than 0.3 has a small unloaded Q value of 300 or less, and a composition in which Excluded.

Thus, according to the above example, (Pb+-xcaJ (Mg+zsNbzz+) +-
In the dielectric ceramic composition represented by y(Ni+zsNbzzs), X is 0.3≦X6, and y is 0.0<
Since y < 1.0, a high dielectric constant, a high Q value in the microwave region, and excellent temperature characteristics can be obtained.

Effects of the Invention As is clear from the above embodiments, the present invention has a high no-load Q.
As a result, it is possible to obtain a small temperature change rate of the resonant frequency, and to improve the dielectric constant in the microwave region, making it possible to downsize the dielectric resonator. Therefore, it greatly contributes to the miniaturization of microwave equipment such as car phones and portable phones. Furthermore, the dielectric ceramic composition according to the present invention can be used not only for dielectric resonators but also for microwave circuit boards, etc., and has extremely high industrial value.

Claims (1)

[Claims] A dielectric ceramic composition comprising lead oxide, calcium oxide, nickel oxide, magnesium oxide and niobium oxide,
Composition formula (Pb_1_-_xCa_x) (Mg_1_/_3Nb
_2_/_3)_1_-_y(Ni_1_/_3Nb_
2_/3) A dielectric ceramic composition characterized in that, when expressed as _yO_3, x and y are in the range of 0.3≦x≦0.6 0.0<y<1.0.