JPH01227304A - Microwave dielectric porcelain composition material and manufacture thereof - 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 Industrial Application] The present invention relates to a microwave dielectric ceramic composition used for dielectric resonators, filters, etc. and a method for producing the same. In addition to improving the properties, the properties can also be improved by changing the calcination method.

[Prior art]

Dielectric filters are used as filters for mobile communications, etc., which utilize bands from several hundred MHz to GHz.

As the material of this dielectric filter, MgO-Ca0-T
iO□ series and Bi4Ti3O12. A variety of ceramic compositions are used, such as those with excellent dielectric constant and Q1 temperature characteristics.

One such composition is BaO-TiO□-Nd
There is one consisting of 203. This system has a higher dielectric constant than the above-mentioned systems, and the resonator and filter can be made smaller. Several samples were prepared using this component system and their properties were measured as shown in the table below.

Further, when expressed as the hatched part of the ternary diagram as shown in FIG.
0.67.0≦Y≦71.0.14.0≦Z≦24.5
(mol%) (However, in the range of X+Y+Z=1), the dielectric constant was 60 or more, Q was 3800 or more, and the temperature coefficient was 70 or less, which was found to be within a usable range.

As shown in the above table, even in a ternary system, there is a point where the temperature coefficient becomes O, but at this point, Q is small, and it is desirable to have good temperature characteristics in a high Q region. Of course, it is desirable that the dielectric constant be high in order to downsize the resonator and filter.

[Problem to be solved by the invention]

The present invention aims to obtain a microwave dielectric ceramic composition having excellent properties in terms of dielectric constant, Q, and temperature characteristics.

In particular, the present invention aims to obtain a microwave dielectric ceramic composition that has improved temperature characteristics while maintaining a high Q value.

Furthermore, by improving methods such as calcination and addition, it is intended to significantly improve the characteristics of Q in particular.

[Means to solve the problem]

The present invention solves the above problems by adding Bi4Tia012 and AltO to the basic composition of BaO-Ti02-NdzOs.

In addition, after calcination at a relatively high temperature, Bi, Ti, 0° and Ah
By adding Os, the characteristics are further improved.

That is, it consists of BaO, TiO2, and Nd2O3, and is expressed by the general formula % (X + Y + Z = 1) (7) For 100 parts by weight of the composition in the range, 5 to 12 parts by weight of old Ti This dielectric ceramic composition for microwave use is characterized in that 2 parts by weight of Altos is added.

Also, to produce this composition, BaO1TiO
2. Produce a calcined material made of Nd2O2, and add Bi4 to it.
This is a method for producing a dielectric ceramic composition for microwave use, which is characterized in that TizO+t and AltO are added and fired.

BaO, TiO2, Nd, 03 have a firing temperature of 85 to 96
%, that is, 1120 to 1250 @C, and then BinTi5O+□ and Alz(h) are added thereto and fired at a predetermined temperature.

〔Example〕

Examples of the present invention will be described below.

The characteristics of a sample of a dielectric ceramic composition in which only Bi4TizO+t was added to the above three components were as shown in the following table.

(BidizO□ is weight%, others are mol%) Figure 2 shows the change in properties depending on the calcination temperature when 12-t% of Btdi30+□ was added to the basic composition of sample 2. be.

In this way, Bi Mio Ti3. If an attempt was made to obtain a composition with good temperature characteristics by adding only z, there was a problem that Q would decrease.

Therefore, as a result of considering improvement of the characteristics, we found that this composition had A11
(It was found that adding a small amount of h significantly improves the temperature characteristics.

When producing this porcelain composition, BaC0, TiO
A method was adopted in which a predetermined amount of NdzO* was weighed, mixed in a ball mill for 24 hours, dried, and then calcined at 1000 to 1100 '' C.The calcined product was again mixed in a ball mill with Bi4TiiO+z and AI!03 at a predetermined weight percent. After pulverization and wet mixing, a binder was added and granulated using a spray dryer.
Molded at a pressure of 0Kg/caa", 1300~1350
Samples were prepared by firing at °C.

This sample was measured at 3 to 4 GH2 by the HAKKI & COLEMAN method to determine the dielectric constant εr, Q, and temperature coefficient τf, respectively. The results were as shown in the table below.

In this way, although the dielectric constant and Q were slightly lowered, the temperature characteristics could be improved by adding a small amount.

Furthermore, it was confirmed that Q could be significantly improved by changing the method of calcination of the basic components.

The method will be explained below.

As mentioned above, in the conventional ceramic manufacturing method,
The necessary raw material powders are weighed and mixed, calcined at a low temperature that does not cause grain growth, and then crushed, molded, and fired. That is, calcination is carried out at a low temperature at which the densification of the calcination can be achieved by gas, which is 70 to 80% of the normal calcination temperature. If the temperature is too high, it cannot be densified when fired, and there is no need to calcinate it at such a high temperature.

In the present invention, a composition consisting of BaOTiltNdzOs is calcined at high temperature, and then Bi, Ti, O□ and Al
This is based on experimental results showing that when 2O3 is added and fired, Q characteristics in microwaves are significantly improved.

In producing the microwave dielectric ceramic composition according to the present invention, predetermined amounts of BaCO3, TiO2, and Nd2O3 were weighed, mixed in a ball mill for 24 hours, dried,
The calcined product was calcined at 20 to 1250" C. After pulverizing the calcined product again using a ball mill, predetermined amounts of BinTi30+z and Alz03 were added, a binder was added, and the mixture was mixed for 2 hours and granulated using a spray dryer. This granulated material was 12Φ ×1011
Samples were prepared by molding to I11 and firing at 1300-1350''C.

For comparison with the example shown in Fig. 2, Bi4TiiO+
FIG. 3 shows the relationship between calcination temperature and characteristics when only z is added. It can be seen that when the calcination temperature is 1150''C or higher, the Q after calcination is significantly improved.

From the above results, we found that the basic materials of BaO-Tie and -NdzO were heated at a firing temperature of 85 to 9
It was found that by calcining in the range of 6%, the dielectric constant decreased slightly, but the Q was significantly improved.

Although the reason for the above improvement in Q has not been fully elucidated, it is thought that crystal grain growth and intragranular diffusion of Bi are related.

With this composition, BinTi30+z becomes a liquid phase at temperatures above 800''C and promotes sinterability, so that good porcelain can be obtained without a large decrease in density.

Bi4. FIG. 4 shows the results of measurements with varying amounts of TizO+z added. In the above formula, X=14(le%, Y
= 69 upper 69 mo X = 17 mol%, 3i
The results were measured by changing the amount of di30 and □ added. As the amount added increases, Q decreases, and if it exceeds 20 wt%, Q becomes 3000 or less, making it unsuitable for practical use.

In addition, the results measured by changing the amount of A1.03 added are shown in the fifth column.
As shown in the figure. In the above formula, X = 10 on 10 mo Y = 6
Broken line 22 shows the temperature characteristic τf when AhOs is added to the basic composition of 9% by weight, X=21, and the amount added is changed. It was 30 ppm when no additive was added, but it became almost O at 1.0 wt%. Also, X=13u
%, Y = 70-t8%, X = 17t$%, the solid line 21 shows the case. As the amount added increases, the temperature characteristics improve, and at 2.0 wt% it is approximately 5 ppm.
I was able to lower it to Adding more than this has almost no effect and causes deterioration of other properties, so it is desirable that the upper limit of the amount added be 2.0eet%.

〔effect〕

According to the present invention, it is possible to obtain a dielectric ceramic composition for microwave use that has extremely good properties when considering the dielectric constant, Q, and temperature properties comprehensively.

In particular, a dielectric ceramic composition for microwave use can be obtained which has extremely good temperature characteristics while maintaining a high dielectric constant and Q.

Further, by improving the manufacturing method, it becomes possible to minimize the decrease in Q.

[Brief explanation of the drawing]

Figure 1 is a ternary diagram showing the basic composition of the dielectric ceramic composition of the present invention, Figures 2 and 3 are explanatory diagrams of changes in properties depending on the calcination method and temperature, and Figure 4 is an illustration of the addition amount and Q. An explanatory diagram showing the relationship between
FIG. 5 is an explanatory diagram showing the relationship between addition amount and temperature characteristics.

Claims (4)

[Claims] (1) Consists of BaO, TiO_2, Nd_2O_3,
This is converted into the general formula XBaO+YTiO_2+ZNd_2O_
3, X, Y, and Z are each 8.5≦X≦
19.0, 67.0≦Y≦71.0, 14.0≦Z≦2
4.5 (mol%) (where X+Y+Z=1), Bi_4Ti_
5 to 12 parts by weight of 3O_1_2 is added, and Al_2O_
1. A dielectric ceramic composition for microwave use, characterized in that 2 parts by weight or less of 3 are added. (2) Produce a calcined product consisting of BaO, TiO_2, and Nd_2O_3, and add Bi_4Ti_3O_1_2 and A
2. The method for producing a microwave dielectric ceramic composition according to claim 1, wherein l_2O_3 is added and fired. (3) BaO, TiO_2, Nd_2O_3 are calcined at a temperature of 85 to 96% of the firing temperature, and Bi_4Ti_
3. The method for producing a microwave dielectric ceramic composition according to claim 2, wherein 3O_1_2 and Al_2O_3 are added and fired at a predetermined temperature. (4) The method for producing a microwave dielectric ceramic composition according to claim 2, wherein the calcination temperature of BaO, TiO_2, and Nd_2O_3 is 1120 to 1250°C.