JP2687287B2 - Dielectric ceramic composition for microwave and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition for microwaves, which is suitable as a material for a dielectric filter or the like used in the microwave band, and a method for producing the same. .

(Prior art)

As a dielectric ceramic composition for microwaves for a dielectric filter, a dielectric ceramic composition having a dielectric constant of about 40, a high Q in the microwave band, a small temperature coefficient of resonance frequency, and excellent linearity. Is required.

Conventionally, BaO-TiO-based materials have been used as materials with a dielectric constant of around 40.
Although BaTi ₄ O ₉ and BaTi ₉ O ₂₀ are known, some of these materials have a characteristically small region, but have a large frequency temperature coefficient (τf) and are non-linear. was there.

Further, in terms of manufacturing, the sintered body is easily reduced, Q is greatly deteriorated or fluctuated, and it is difficult to control the crystallinity of BaTi ₉ O ₂₀ or the like.

It has been attempted to add Zr to a Ba-Ti composition or to form a solid solution for controlling the crystallinity (Japanese Patent Publication No. 56-3800).
No. 7, JP-A-60-26436, etc.), it is said that unless it is 3.7 wt% or 8 mol% or less, characteristics such as Q are deteriorated and it is not suitable for practical use.

〔Task〕

The present invention aims to improve the sinterability of a BaO—TiO based dielectric ceramic composition for microwaves and obtain a composition that is difficult to reduce.

Further, it is intended to obtain a dielectric ceramic composition for microwaves having a high Q in a wide range and a small temperature coefficient.

[Means for solving the problem]

The present invention solves the above problems by adding ZrO ₂ to obtain a ternary microwave dielectric ceramic composition.

That is, in the composition represented by the general formula Ba (Ti _1-x Zr _x ) _y O _{2y + 2} , the values of x and y are 0.02 ≦ x <0.20 4.5 <y <7.3 It is a body porcelain composition.

Further, the powder particle size of the starting material is reduced to obtain a dielectric ceramic composition for microwaves having better characteristics.

That is, using BaCO ₃ , TiO ₂ , and ZrO ₂ as starting materials, the powder particle size of ZrO ₂ was made to be almost the same as the powder particle size of TiO ₂ (about 0.3 μm), and the above dielectric ceramic composition for microwaves was manufactured. To do.

〔Example〕

 Hereinafter, examples of the present invention will be described.

BaCO ₃ (average particle size D ₅₀ = 1.5 μm) TiO ₂ as a starting material
(Average particle size D ₅₀ = 0.28 μm) and ZrO ₂ (Average particle size D ₅₀ =
0.31 .mu.m, using a 0.9 .mu.m), the _{Ba (Ti 1-x Zr x} ) y O 2y + 2 composition formula, x shown in Table 1, weighing in the range of y,
Was blended. This was wet mixed with a ball mill for 16 hours to dry the water, and then calcined at 1000 ° C. for 2 hours.

This calcined product is again ball milled with an organic binder (PVA
Etc.), a plasticizer, etc. for 20 hours, and the obtained slurry was granulated by a spray dryer. Then, the mixture was compression-molded into 12.0Φ × 10 mm at a pressure of 1.0 to 1.5 ton / cm ² , the binder was removed, and then the mixture was baked at 1320 to 1380 ° C. for 2 hours.

The obtained sintered body was polished to 9.0Φ × 8mm, and the non-dielectric constant (ε) was measured at about GGHz by density measurement and HAKKI & COLEMAN method.
r), Q and temperature coefficient (τf) were measured.

 Table 1 shows the results.

The value of Q is f × Q = constant and is shown as a value converted to a value of 1 GHz.

Outside the above range, sufficient characteristics cannot be obtained, such as a decrease in Q and a large variation thereof.

The above sample uses a material having a ZrO ₂ particle size of 0.31 μm. The results when the ZrO ₂ particle size is 0.9 μm are shown in Table 2.
Shown in

Comparing Table 1 and Table 2, the particle size of ZrO ₂ is 0.31
It is shown that the characteristics are improved when μm is set.

From the above results, it is possible to obtain a stable sintered body that is difficult to reduce even in a composition range that was conventionally difficult, and has a high Q value.
A composition with a small temperature coefficient was found.

It was confirmed that the higher the content of ZrO ₂ in the range of x <0.23, the better the sinterability, and that it was a single phase in terms of X-ray up to x <0.1. Further, when 0.1 <x <0.23, although it is a composite crystal, it suppresses the generation of TiO ₂ , which affects the increase of the temperature coefficient.

It should be noted that, when the above-mentioned value of x is converted into mol, the range is from about 3.5 mol% to 21 mol%.

It was also confirmed that, as the powder raw material of ZrO ₂ to be used, the one having high reactivity and small grains was used, the range of good crystallinity and good characteristics was widened.

〔effect〕

According to the present invention, by containing a relatively large amount of ZrO ₂ ,
A dielectric ceramic composition for microwaves having good crystallinity, hardly reduced, and stable characteristics can be obtained.

Further, even if a relatively large amount of ZrO ₂ is contained, a dielectric magnetic composition for microwaves having a high Q and a small temperature coefficient can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 60-257008 (JP, A) JP 59-26969 (JP, A) JP 60-264361 (JP, A) JP 62- 30682 (JP, B2)

Claims (3)

(57) [Claims] 1. A composition represented by the general formula Ba (Ti _1-x Zr _x ) _y O _{2y + 2 in} which the values of x and y are in the range of 0.02 ≦ x <0.20 4.5 <y <7.3. Wave dielectric ceramic composition. 2. The microparticles according to claim 1, wherein BaCo ₃ , TiO ₂ , and ZrO ₂ are used as starting materials, and the powder particle size of ZrO ₂ is substantially the same as the powder particle size of TiO _2. A method for producing a dielectric ceramic composition for waves. 3. The method for producing a dielectric ceramic composition for microwaves according to claim _{2, wherein} the powder particle size of ZrO ₂ is about 0.3 μm.