JPH02307865A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a dielectric porcelain composition increased in dielectric constant, reduced in changes in resonance frequency against temp. as well as in dielectric loss, and used in a microwave region by adding specific trace amounts of Mn compound to a raw material consisting principally of TiO2 and containing BaO, Sm2O3, molding the resulting mixture, and then sintering the composition. CONSTITUTION:BaO, Sm2O3, TiO2, and Bi2O3 are mixed into a proportion represented by a formula [where the symbols (x), (y), (z), and (w) represented by 0.110-0.170, 0.120-0.185, 0.630-0.710, and 0.020-0.090, respectively, and x+y+z+w=1]. Then, MnCO3 is further added and incorporated to the resulting mixture so that its content is regulated to 0.003-0.3wt.% expressed in terms of Mn, which is subjected to wet grinding to the full by means of a ball mill. Subsequently, the resulting ground material is dried, dehydrated, pelletized by the addition of binder, pressure-molded into the prescribed shape, and sintered in the air at high temp., by which the dielectric porcelain composition can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dielectric ceramic composition suitable as a resonator or circuit board material in the microwave region.

(Prior art) In recent years, microwave circuit I
Dielectric ceramics are being widely used in the microwave region, such as the development of C, the expansion of the range of use of Gunn oscillators, and the application to oscillators using gallium arsenide field effect transistors.

Such dielectric ceramics for microwaves are mainly used in resonators, and the characteristics required there are (1) a dielectric constant as high as possible for miniaturization, and (2) a small dielectric loss. , (3) The main reason is that the change in resonance frequency with respect to temperature is small.

Conventionally, as this type of dielectric porcelain, for example, Bad-
Tie, based material, Ba0-REO-TiOz (however, R
EO is a rare earth element oxide, the same applies hereinafter) type material and (Ba
SrCa)(ZrTi)Os-based materials are known.

(Problems to be solved by the invention) However, Bad-Tie□-based materials and (BaSrC
a) (ZrTi)0. Although the material has an extremely low dielectric loss in a high frequency band of 4 to 10 GHz, the dielectric constant is as low as 29 to 40, which poses a practical problem in miniaturization, especially in a frequency band of around IGHz. Furthermore, when the dielectric constant is increased, the temperature characteristics of the resonance frequency or the dielectric loss tend to deteriorate extremely.

In addition, Ba0-REO-TiOz material-based material is Ba0-REO-TiOz-based material.
n-Nd, 03-Tie, system or 8aO-5m, 0
3-TiO At present, a dielectric ceramic composition that has both the above-mentioned three properties has not yet been developed.

(Object of the Invention) The present invention was devised in view of the above-mentioned drawbacks, and in order to make it possible to downsize the resonator, it has a high dielectric constant (80 or more),
It is an object of the present invention to provide a dielectric ceramic composition for high frequency use, which has a low dielectric loss, a small and stable temperature dependence of the dielectric constant, and a small and stable temperature dependence of the resonant frequency of a dielectric resonator. .

(Means for solving the problem) As a result of repeated research on the above problem, the present inventors found that the main components are BaO, 5111203, TtOz and Bi.
. The above object is achieved by adding a Mn compound at a ratio of 0.003 to 0.3% by weight in terms of metal to a composition adjusted to have a composition expressed as 090 x + y + z + w = 1. This is what we discovered.

(Function) According to the above configuration, by adding Biz(h) to the Ba0-REO-T ioz system, the dielectric constant can be increased and τf can be shifted from the conventional negative side to the positive side, but it is possible to If too much Bi2O3 is added to aim for a higher ratio, τ
f becomes thicker on the positive side (although, if SmtO is selected as the RED component in this system, τf can be shifted to the negative side, and the effect of adding Bi, 03 can be further brought out. SmtO,, -Ti02-
In the Biz03 system, the dielectric loss (2) of the three characteristics described above is large (the Q value is low), so by adding a Mn compound to this system, the reduction resistance and Q value are improved, and the three characteristics described above are improved. A fully satisfactory dielectric ceramic composition can be provided.

In addition, in the present invention, the reason why the amount of each component is limited to the above-mentioned ratio will be made clear from the examples described below. As τf increases to the positive side, X becomes 0.
If it is smaller than 110, the Q value will be low. y value is 0.1
If it is larger than 85, the dielectric constant will be low, and if it is smaller than 0.120, the Q value will be low. When the y value is larger than 0.710, τf increases to the positive side, and when it is smaller than 0°630, the dielectric constant and Q value decrease.

If the radius is larger than 0.090, the Q value will be low and τf will be large on the positive side, and if it is smaller than 0.020, the dielectric constant will be low. If the amount of the Mn compound as an additive deviates from the above-mentioned range, the Q value will become low, which is not preferable.

When producing porcelain in the present invention, oxides of the metals constituting the porcelain or compounds that can be converted into oxides by firing, such as carbonates, nitrates, sulfates, etc., are weighed and mixed, and then heated to a temperature of 900 to 1200, if desired. Calcinate at °C.

After molding this mixture or calcined powder,
Porcelain can be obtained by firing in an oxidizing atmosphere at 50°C.

Moreover, MnO is preferable as the Mn compound, and MnC0 is the most preferable as the addition form.

The invention will now be explained with the following examples.

(Example) High purity barium carbonate (BaCO:+) as a starting material
, samarium oxide (SlnzO+), titanium oxide (T
After weighing powders of bismuth oxide (Bizoz), bismuth oxide (Bizoz), and manganese carbonate (MnCOz) to the proportions shown in Table 1, pure water was added and ball milling was performed for 20 hours.

After drying this mixture, it was calcined at 900°C for 2 hours, and the calcined product was mixed again in a ball mill for 20 hours and then dried. Approximately 1 wt% binder is added to the dry powder, and the particles are sized to form approximately 1 wt% binder.
Pressure molded into a 20φ cylinder at a pressure of 1 ton/cm".
Calcined in air at 150-1450'C for about 2 hours.

The obtained cylindrical porcelain was surface-polished and cylindrical-ground to a diameter of approximately 1
An undistorted cylindrical sample of 6 mm and height of about 8 mm was obtained.

Using this sample, the dielectric constant (εr) and Q at a resonance frequency of 2.3 to 2.8G)
The temperature coefficient (rf) of the resonant frequency was measured.

rf -40 to +25°C and +25°C to +85
Measured in °C.

The results are shown in Table 1.

(Leaving space below) As is clear from Table 1, samples that deviate from the scope of the present invention do not achieve sufficient characteristics in the three characteristics, whereas the present invention has a dielectric constant of 80 or more, a Q value of 700 or more,
1τf1≦17.3ppm/”C was achieved.

(Effects of the Invention) As detailed above, the porcelain composition of the present invention has BaO-Sm
By adding a Mn compound to the J3-TiOz-Biz03 system, it has excellent properties in the microwave region such as a dielectric constant of 80 or more, a value of 700 or more, and a τf±17.3ρρm/'C or less, and has microwave resonance. When used as porcelain, it is possible to miniaturize the resonator and improve its performance.

Claims (1)

[Claims] The compositional formula is xBaO・ySm_2O_3・zTiO_2・wBi_
2O_30.110≦x≦0.170 0.120≦y≦0.185 0.630≦z≦0.710 0.020≦w≦0.090 x+y+z+w=1 Mn compound as the main component in metal terms 0.003,
A dielectric ceramic composition containing the dielectric ceramic composition in a proportion of 0.3% by weight.