JPS6236064A - Dielectric ceramic composition for microwave - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to a dielectric ceramic composition for microwave use, which has a large relative dielectric constant εr, a small dielectric loss in the microwave band, and which has The present invention relates to a microwave dielectric ceramic composition whose temperature coefficient of dielectric constant can be selected over a relatively wide range.

BACKGROUND ART In recent years, a new development in the use of dielectric materials has begun. It is a dielectric resonator with a different concept from conventional applications such as capacitors.

In general, it takes advantage of the fact that dielectrics are propagation media for electromagnetic waves, and it focuses on the fact that the wavelength of electromagnetic waves in dielectrics is 1/Jεr compared to that in vacuum, and actively utilizes this. This design is designed to reduce the size of circuit elements.

Conventional microwave band circuit elements have been waveguides and cavity resonators, but they are large, heavy and unsuitable for use in communication systems such as satellite communication and mobile communication means, which have seen remarkable progress in recent years. Therefore, there has been a particular demand for miniaturization and improved reliability of component single circuit elements in which these microwave bands are used.

Such microwave dielectric materials include CaTi
Os Mo T, 03 series, (Zr, Sn) TyO
t series, Ba2 Ti9010 series and BaO-Nd203-
Ti02 series and BaOSm2O3Ti0t series are well known.

Ca Ding L 03-MgTiOs-based material has low loss and a small temperature coefficient of dielectric constant, but has a small dielectric constant of 20.

In addition, (Zr, Sn) That series and Ba2 Tig
O10-based materials also have low loss and low temperature coefficient, but
The dielectric constant is about 40.

In addition, BaONd2O3Ti02 system, BaO-5n20
3-TLO2-based materials have a high relative dielectric constant of 60 to 80 and a low temperature coefficient, but the dielectric loss in the microwave band is 5.
It is small at about GH2 and Q=1000 or less.

However, today there is a strong demand for low-loss materials.
BaOSm203TLOe series is BaONd203
Compared to the Ti02 system, it has a similar dielectric constant (εr = 80
) and have low loss, but since Sm2O3 is used as a raw material, the material cost is high, and when used in large quantities, there is concern about raw material supply, making it difficult to stably supply the welding material. It is.

Purpose of the Invention In view of the above-mentioned problems, this invention has a high dielectric constant, allows the temperature coefficient of the dielectric constant to be selected relatively freely, and has a much lower loss than conventional materials as a dielectric material for microwaves. The aim is to create a cheaper dielectric material for the microwave band.

Structure and effect of the invention As a result of various studies aimed at creating a dielectric ceramic composition that satisfies various properties required for dielectric materials for microwaves, the present invention has revealed that a BaO-La2O3'' TiO2a 5nap-based material has a high dielectric constant. It has low dielectric loss, and the temperature coefficient of dielectric constant can be set by selecting its composition, making it ideal as a dielectric material for microwave bands.As it is a porcelain composition made of elements that are abundant in resources, it is different from conventional materials. This is based on the knowledge that it can be provided at a lower price.

That is, in this invention, the basic compositional formula is
2.wSn02, and when xy+z+w=100 mol%, the symbols x, y, z, and w that limit the composition range satisfy the following formula: Yes, 0<x≦17.5 mol% 12.5≦y≦35.0 mol% 52.5≦z≦71.5 mol% 0<w≦5.0 mol% Furthermore, the basic composition formula is XBaO・'/LazO3・
Z TLO2-WSn02 φV PbO, x
When +y+z+w=100 mol%, the dielectric ceramic composition for microwaves is characterized in that the symbols x, y, z, w, and v that limit the composition range satisfy the following formula.

0<x≦17゜5 mol% 12.5≦y≦35.0 mol% 52.5≦z≦17.5 mol% 0<w≦5.0 mol% <VS2
．． 0 mol% Reason for limiting the composition The dielectric ceramic composition according to the present invention is composed of: BaO-La203・TiOt・SnOt・PbO
The composition range is as follows.

If BaO exceeds 17.5 mol%, the temperature coefficient of the resonance frequency will exceed 300 ppm/'C, which is inappropriate for practical use, so the content is set to 17.5 mol% or less.

La2O3 is more than 35 mol% and less than 12.5 mol%,
If TiO2 exceeds 71.5 mol% and is less than 52.5 mol%, the sinterability of the ceramic composition will deteriorate, making it impossible to obtain a high-density sintered body, resulting in a decrease in Q value, and micro La2O212.5-35. is unsuitable as a wave dielectric material.
0 mol%, TiO, 52.5 to 71.5 mol%.

When SnO2 exceeds 5 mol%, the dielectric constant decreases and the Q
Since it causes a decrease in the value and is unsuitable as a dielectric material for microwaves, the content is limited to 5 mol% or less.

PbO is effective in improving the sinterability of Ba0-Li2O2 and 02-SnO2-based dielectric ceramic compositions, as well as in improving the dielectric constant and dielectric loss, but if the content exceeds 7 mol%, the Q Since the value decreases and it is not suitable for practical use, the content should be 1 mol% or less.

Example TLO2 with purity of 99.5% or more, BaC0: +, S
T+02. L1203.

Using PbO, various compositions shown in Table 1 (test slope 17
-15 is outside the scope of the present invention), mixed in a ball mill for 5 hours, dried and heated at 1iooC.
Calcination is performed for several hours, then the calcined powder is crushed, a binder is added and molded, and the binder is removed.
Sintered under temperature conditions of 300℃ to 1500℃, outer diameter 17n
A cylindrical sintered body with a vnX height of 10 mm was produced.

The obtained sintered body was heated at 25°C, 5.5(3)(
Under conditions of approximately Z, the relative dielectric constant εr and Q@ were measured, and the temperature coefficient τf of the resonance frequency was also measured. The measurement results are
It is shown in Table 1 along with the composition.

As is clear from Table 1, the dielectric ceramic composition according to the present invention can have a wide temperature coefficient of resonance frequency, exhibits low loss and high magnetic permeability, and is ideal as a dielectric material for microwaves. I understand something.

Below margin

Claims (1)

[Claims] 1. The basic compositional formula is xBaO・yLa_2O_3・zTiO_2・wSnO
_2, and when x+y+z+w=100 mol%, symbols x, y, z, and w that limit the composition range satisfy the following formula. 0<x≦17.5 mol% 12.5≦y≦35.0 mol% 52.5≦z≦71.5 mol% 0<w≦5.0 mol% 2. The basic compositional formula is xBaO・yLa_2O_3・zTiO_2・wSnO
A dielectric ceramic composition for microwave use, which is expressed as _2, vPbO, and when x+y+z+w=100 mol%, symbols x, y, z, w, and v that limit the composition range satisfy the following formula. 0<x≦17.5 mol% 12.5≦y≦35.0 mol% 52.5≦z≦71.5 mol% 0<w≦5.0 mol% For x+y+z+w=100 mol%, 0 <v≦7.0 mol%