JPH0817053B2 - Method for manufacturing sintered body for high frequency dielectric - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sintered body for high frequency dielectric.

[0002]

2. Description of the Related Art Conventionally, Ba has been used as a high frequency dielectric sintered body having a high dielectric constant and a high Q value in the microwave region.
There is a perovskite type high frequency dielectric sintered body represented by Mg _1/3 Ta _2/3 O ₃ (= Ba ₃ MgTa ₂ O ₉ ) (hereinafter, appropriately referred to as “BMT sintered body”).

This high-frequency dielectric sintered body is obtained by calcining a calcined material obtained by calcining a raw material mixture and sintering it. However, it is generally said that it is difficult to obtain a BMT sintered body having a good dielectric property with a high yield. This is because the density of the obtained sintered body is low, and the sintered body often has cracks.

In order to increase the compactness, a method has been proposed in which the temperature rising rate in the main firing is rapidly increased to 100 ° C./minute, but in this rapid temperature raising firing, the firing cost is high and an electronic device (for example, , And resonator) are difficult to reduce in price, and thus are not suitable for mass production and are not practical.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a method capable of easily producing an inexpensive high frequency dielectric sintered body having excellent dielectric properties.

[0006]

In order to solve the above-mentioned problems, the inventor has studied the BMT sintered body from various directions and found the following. That is, 100
The sintered body obtained by using the powder of the calcined product that is calcined at about 0 to 1100 ° C. does not have sufficient dielectric properties because of the occurrence of cracks, but has sufficient compactness. The cracks are generated because BaCO ₃ and MgO which remain unreacted in the calcined product.
It was considered that the three members, BaTa ₂ O ₆ and BaTa ₂ O ₆ , re-react during the firing process. On the other hand, it has been found that the sintered body obtained by firing the powder calcined at about 1300 to 1400 ° C. does not have cracks but is inferior in compactness. Therefore, as a result of detailed examination of the cause of the poor compactness, the calcination temperature was 130
In the case of 0 to 1400 ° C., MgO hardly remains because the reaction has proceeded sufficiently, but the calcination temperature is 1000 to 11
It was speculated that this may be because MgO remains at a temperature of 00 ° C. Based on this assumption, BaMg _1/3 Ta _2/3 O ₃ which has been sufficiently fired at a temperature exceeding 1300 ° C.
It is presumed that if a small amount of MgO is positively added to the hardly-sinterable calcination product represented by the above, it is possible to obtain a sintered compact having a high density while suppressing the occurrence of cracks,
As a result of confirming the correctness of this estimation through experiments, the present invention could be completed here.

Accordingly, the production method of the dielectric-body sintered body according to the present _{invention, Ba, Sr, Ba 1-} x Sr x ( however
And any one of 0 <X <1) or an element
A representing a group and any one of Mg, Zn, Ni, and Mn
B, which represents one element, and one of Ta and Nb
The composition ratio of C representing an element and O representing oxygen is AB _1/3.
In obtaining a perovskite high-frequency dielectric-body sintered body is represented by C _2/3 O _3, in AB _1/3 C _2/3 O ₃ added B oxide calcined product represented by and 1300 ° C. or higher < br /> fired. A of precalcination and B oxides represented by AB _1/3 C _2/3 O ₃ in the present invention, B, C before Symbol A,
It is appropriately selected from B and C and combined.

[0008] For example, in the case of a BMT sintered body,
The calcined product is BaMg_1/3Ta_2/3O₃Depiction
The B oxide is MgO.

The amount of the B oxide added to the calcined product is usually 3 to 8 mol per mol of the calcined product as claimed in claim 3.
1%, more preferably 4 to 6 mol%. Three
If it is less than mol%, the effect of increasing the compactness tends to be insufficient, and if it exceeds 8 mol%, it is rather difficult to obtain a sintered body having sufficient dielectric properties and densification. The combination of the calcined product and the added oxide for obtaining the perovskite-type high frequency dielectric sintered body is BM described above.
In addition to the case of T, the following may be mentioned. (A) Calcined product; BaZn _1/3 Ta _2/3 O ₃ oxide; Zn
O (b) Calcined product; BaNi _1/3 Ta _2/3 O ₃ oxide; Ni
O (c) calcined product; BaMn _1/3 Ta _2/3 O ₃ oxide; Mn
O (d) calcined product; BaMg _1/3 Nb _2/3 O ₃ oxide; Mg
O (e) Calcined product; BaZn _1/3 Nb _2/3 O ₃ oxide; Zn
O (f) calcined product; BaMn _1/3 Nb _2/3 O ₃ oxide; Mn
O (g) calcined product; SrMg _1/3 Ta _2/3 O ₃ oxide; Mg
O (h) calcined product; SrZn _1/3 Ta _2/3 O ₃ oxide; Zn
O (i) Calcined product; SrNi _1/3 Ta _2/3 O ₃ oxide; Ni
O (j) calcined product; Ba _1-x Sr _x Mg _1/3 Ta _2/3 O ₃ oxide; MgO (k) calcined product; Ba _1-x Sr _x Ni _1/3 Ta _2/3 O ₃ oxide Material; NiO Hereinafter, the present invention will be described by taking a case of a BMT sintered body as an example.
This will be specifically described.

According to the stoichiometric ratio of BaMg _1/3 Ta _2/3 O ₃ , the starting materials BaCO ₃ , MgO and Ta ₂
Weigh each powder of O ₅ . Usually, the average particle size of each powder is as follows. BaCO ₃ powder: about 1 to 15 μm MgO powder: about 1 to 15 μm Ta ₂ O ₅ powder: about 1 to 15 μm BaO may be used instead of BaCO ₃ , but BaC
O ₃ with high purity and uniform particle size can be obtained at low cost.

Pre-calcination is performed at a temperature of 1000 to 1100 ° C. The preliminary calcination is MgO during the subsequent calcination or main calcination.
This is to suppress the volatilization of the. However, this preliminary calcination may be omitted. The powder that has undergone the preliminary calcination is cooled, ground in pure water for about 24 hours using a ball mill, dried and then dried.
Calcination is performed at a temperature of 00 to 1400 ° C. for 2 to 10 hours. This calcination is preferably performed twice or more. By repeating the calcination, the uniformity of the composition is enhanced. Further, the calcinated product is crushed and stirred for each calcination. This calcined product
It is represented by BaMg _1/3 Ta _2/3 O ₃ . The average particle size of the powder obtained by crushing after the final calcination treatment is about 1 to 15 μm.

The reaction in the calcining step is as follows.

Embedded image Is. MgO powder is added in an amount of α mol% (provided that 0 <α ≦ 8) to 1 mol of the obtained calcined powder, and the mixture is pressed to obtain a green compact having a predetermined shape. The average particle size of the added MgO powder is about 1 to 15 μm.

MgO is usually used alone, but may include other oxides such as BaTa ₂ O ₆ .
As described above, since it is only necessary to add a small amount of MgO, which is one of the raw materials, to a product that has been calcined at a temperature of 1300 ° C. or higher, it is possible to manufacture it extremely easily and inexpensively. The calcination temperature is preferably 1300 ° C. or higher. this is,
This is because the reaction between the raw materials is sufficiently promoted, and it is possible to prevent the unreacted raw materials that inhibit the densification from remaining in the calcined product. In particular, the diffraction line (10
.2), (20.2), (21.2), (20.4) and (21.4) half-widths of 0.20 °,
0.22 °, 0.29 °, 0.33 ° and 0.36 °
Those calcined as described below tend to have a high compositional uniformity and a sufficient Q value.

After that, main firing is performed. (1) Baking is performed at a temperature of 1500 ° C. or higher for 2 to 5 hours.
There is no particular limitation on the heating rate. The firing of (1) is for promoting densification. Then, (2) heat treatment is performed at 1200 to 1450 ° C. for 10 to 120 hours. This treatment (2) is performed to make the BMT crystal an ideal hexagonal crystal.

As a result, an excellent BMT sintered body can be easily obtained.

[0016]

In the present invention, the B oxide added in the main calcination exhibits a function of promoting the sintering of the calcined product represented by AB _1/3 C _2/3 O ₃ and therefore has a dense and crack-free structure. A sintered body can be obtained reliably (with high yield). B oxide, which is added in a small amount, is usually a raw material when making a calcined product and is not special, and it does not require any special treatment such as rapid temperature rising calcination, so it is easy to manufacture and the cost is low. There is no such thing as a high.

When the sintered body for perovskite type high frequency dielectric is represented by BaMg _1/3 Ta _2/3 O ₃ , it is easy to obtain one having excellent dielectric characteristics as compared with the case of using other compositions. . The amount of B oxide added is AB _1/3 C _2/3 O
_{When the} content is ₃ to 8 mol% with respect to 1 mol of the calcined product represented by ₃ , an appropriate sintering promoting action is certainly exhibited.

[0018]

Embodiments of the present invention will be described below. -Examples 1 to 5-BMT sintered bodies were obtained according to the above. However, the addition ratio of MgO to 1 mol of the calcined product is as shown in Table 1.

In the preliminary calcination step, 1100 ° C.
After the treatment for 10 hours, in the calcination step, 1300 ° C,
The treatment for 10 hours was performed twice, the firing was performed at 1600 ° C. for 2 hours in the firing step (1) of the main firing, and the treatment at 1450 ° C. for 100 hours was performed in the firing step (2). The average particle size of the raw material powder is about 4 μm for BaCO ₃ powder.
m, MgO powder is about 4 μm, Ta ₂ O ₅ powder is about 4 μm
Is.

The average particle size of the powder of the calcined product after pulverization is about 4 μm, and the average particle size of the MgO powder added is also about 4 μm.
μm. -Comparative Example 1-A BMT sintered body was obtained in the same manner as in Example 1 except that MgO was not added.

-Comparative Example 2-A BMT sintered body was obtained in the same manner as in Comparative Example 1 except that the calcination temperature was 1100 ° C. With respect to the sintered bodies of Examples and Comparative Examples, the density (relative density of the sintered body) was measured, and the dielectric constant and the Q value were measured by the dielectric cylinder resonance method (measurement frequency 10 GHz). The presence or absence of cracks was also examined. Table 1 shows the measurement results.

[0022]

[Table 1]

Comparing each sintered body of the examples of Table 1 with the sintered bodies of Comparative Examples 1 and 2, the sintered bodies of the examples are dense, have no cracks, and have sufficiently good dielectric properties for practical use. It can be seen that it is a dielectric with.

[0024]

As described above, in the inventions described in claims 1 to ₃ , a small amount of B oxide having a sintering promoting action is added to the calcined product represented by AB _1/3 C _2/3 O _3. Since it is only necessary to do so, it is possible to easily obtain an inexpensive sintered body having excellent high frequency dielectric characteristics. In the invention of claim 2, the composition of the sintered body for perovskite type high frequency dielectric is BaMg.
_{Since it is 1/3} Ta _2/3 O ₃ , the dielectric properties are remarkably excellent and the practicability is high.

According to the third aspect of the invention, since the added amount of the B oxide is 3 to 8 mol%, an appropriate sintering promoting action surely appears.

Claims (3)

[Claims] 1. Ba, Sr, Ba _1-x Sr _x (provided that 0
Represents any one element or element group of <X <1)
A and any one of Mg, Zn, Ni, Mn
B, which represents an element, and one of Ta and Nb,
The composition ratio of C representing O and O representing oxygen is AB _1/3 C _2/3
In obtaining a perovskite high-frequency dielectric-body sintered body represented by O _3, so that firing at AB _1/3 C _2/3 O ₃ added B oxide calcined product represented by and 1300 ° C. or higher A method for producing a sintered body for a high frequency dielectric, comprising: 2. The method for producing a sintered body for a high frequency dielectric according to claim 1, wherein the calcined material is represented by BaMg _1/3 Ta _2/3 O ₃ , and the added oxide is MgO. 3. The high frequency dielectric material according to claim 1, wherein the B oxide is added in a proportion of 3 to 8 mol% to 1 mol of the calcined product represented by AB _1/3 C _2/3 O ₃ . Manufacturing method of sintered body.