JPH0644407B2 - Dielectric porcelain - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dielectric ceramic, and more particularly to a dielectric ceramic suitable for high frequencies having a high unloaded Q in a high frequency region.

[Conventional technology]

Generally, a dielectric resonator or a dielectric substrate used for a signal circuit in a high frequency region such as a microwave or a millimeter wave has a high dielectric constant and a high unloaded Q, and the absolute value of the temperature coefficient of the resonance frequency. It is desired to use a dielectric porcelain having a small value. Conventionally, TiO ₂ -based materials are often used as this type of dielectric porcelain, for example, BaO-TiO ₂ -based, ZrO ₂ -SnO _2-
TiO ₂ based materials, recently Ba (Zn, TA) O ₃ based, Ba (Mg, Ta) O ₃
There are materials for the system. Dielectric porcelain made of these materials has a no-load Q of 3000 ~ at high frequencies of about 10 GHz.
7,000, dielectric constant 20-40, temperature coefficient of resonance frequency is 0
It has a characteristic of around ppm / ° C.

[Problems to be solved by the invention]

By the way, in recent years, the frequencies used in communication devices have become higher, and there is a demand for dielectric porcelain having even higher unloaded Q even in the SHF band used for satellite broadcasting and the like.

Therefore, an object of the present invention is to provide a new type of dielectric porcelain exhibiting a higher unloaded Q.

[Means for solving problems]

That is, the present invention provides a solution to the above-mentioned problems by the general formula (I): (Ba _1-x Sr _x ) (Mg _1-y Ni _y ) _1-u (Ta _1-z Nb _z ) _u O _{2+ (3/2) u} [wherein x, y, z and u are respectively 0 <x ≦
0.25, 0 <y ≦ 0.5, 0 ≦ z ≦ 0.8, 0.61 ≦ u ≦
It is a number represented by 0.72. ] The present invention provides a dielectric ceramic having a composition represented by:

It has been found that the dielectric porcelain of the present invention can obtain a porcelain having not only a high dielectric constant and a resonance frequency with little temperature complication but also a significantly increased unloaded Q in a high frequency region due to such a composition. Is.

That is, in the general formula (I), x, y, z and u
Ranges of 0 <x ≦ 0.25, 0 <y ≦ 0.5,
0 ≦ z ≦ 0.8 and 0.61 ≦ u ≦ 0.72. x is 0, that is, if Sr is not contained, sintering becomes difficult and 0.2
When it exceeds 5, the temperature coefficient of the resonance frequency increases rapidly in the positive direction. When y exceeds 0.5, the no-load Q decreases.
Further, z may be 0, that is, Nb may not be contained,
When it exceeds 0.8, the no-load Q decreases and the temperature coefficient of the resonance frequency becomes too positive.

The method for producing the dielectric ceramics of the present invention is not particularly limited and can be produced by a usual method. For example B
As raw materials for a, Mg, Ni, Ta and Nb components,
Powders of barium carbonate, strontium carbonate, magnesium oxide, nickel oxide, tantalum oxide and niobium oxide are weighed in proportions so as to obtain a porcelain having a desired composition, and they are mixed sufficiently. The mixture is calcined, then crushed and pressure-molded. The obtained molded body is 1500
The dielectric ceramic of the present invention can be manufactured by firing at about 1650 ° C.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Powders of barium carbonate, strontium carbonate, magnesium oxide, nickel oxide, tantalum oxide, and niobium oxide each having a purity of 99.9 mol% were prepared as raw materials,
The values of x, y, z and u in the general formula (I) of these raw material powders should be the same as those of 21 kinds of samples shown in Table 1 (samples marked with * are comparative examples, others are examples). Each sample number was weighed, put into a pot of a ball mill together with pure water, and wet mixed for 16 hours. The mixture was taken out of the pot, dried at 150 ° C. for 5 hours, and then calcined in air at 1000 ° C. for 2 hours. After calcination, crush, 42
The particles were sieved through a mesh sieve. The obtained powder was primary molded into a disk shape having a diameter of 10 mm and a thickness of about 5 mm at a pressure of 500 kg / cm ² using a mold, and then compressed by a rubber press at a pressure of 2000 kg / cm ² to obtain a molded body. . This molded body was fired in an oxygen stream at 1650 ° C. for 4 hours to obtain a porcelain.

The dielectric constant (εr) and unloaded Q (Qu) of the obtained porcelain were measured at a frequency of about 10 GHz by the dielectric cylinder resonator method. Further, the resonance frequency in the temperature range of −10 ° C. to 80 ° C. was measured, and the temperature coefficient (τf) of the resonance frequency at 20 ° C. was calculated. The results obtained are shown in Table 1.

It can be seen from Table 1 that the dielectric porcelains of sample numbers 1 to 9 which are examples of the present invention have a large unloaded Q of 7,000 or more.

〔The invention's effect〕

The dielectric porcelain of the present invention has a very high value of 7,000 or more with no load even in a high frequency region near 10 GHz, and can meet the recent demand for higher frequency usage.

In addition, the absolute value of the temperature coefficient of the resonance frequency is small, and it has a high value of the dielectric constant, which makes it extremely useful as a dielectric ceramic used in high-frequency dielectric resonators and dielectric substrates. is there.

Claims (2)

[Claims] 1. A general formula: (Ba _1-x Sr _x ) (Mg _1-y Ni _y ) _1-u Ta _u O _{2+ (3/2) u} [wherein, x, y and u are respectively , 0 <x ≦ 0.2
5, 0 <y ≦ 0.5, 0.61 ≦ u ≦ 0.72. ] A dielectric porcelain having a composition represented by: 2. A general formula: (Ba _1-x Sr _x ) (Mg _1-y Ni _y ) _1-u (Ta _1-z Nb _z ) _u O _{2+ (3/2) u} [wherein x , Y, z and u are respectively 0 <x ≦
0.25, 0 <y ≦ 0.5, 0 <z ≦ 0.8, 0.61
It is a number represented by ≦ u ≦ 0.72. ] A dielectric porcelain having a composition represented by: