JP3179916B2 - Microwave dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a microwave dielectric ceramic composition and, more particularly, the unloaded Q (hereinafter, simply. As Qu) and dielectric constant (hereinafter, simply epsilon _r of.) The While maintaining the value at a high value, the temperature coefficient of the resonance frequency (hereinafter simply referred to as τf) can be made close to zero, and by further adjusting the addition amount of Co ₂ O ₃ ,
The present invention relates to a microwave dielectric porcelain composition capable of arbitrarily controlling τf to a plus side and a minus side with zero as a center. INDUSTRIAL APPLICABILITY The present invention is used for a dielectric resonator, a microwave integrated circuit board, impedance matching of various microwave circuits, and the like in a microwave region.

[0002]

2. Description of the Related Art Microwave dielectric porcelain compositions (hereinafter simply referred to as dielectric porcelain compositions) tend to increase dielectric loss as the operating frequency increases.
There is a demand for a dielectric ceramic composition having a large Qu in the micro frequency range. As a conventional dielectric porcelain material, a dielectric porcelain composition having a crystal structure including two phases of a perovskite phase and an ilmenite phase (Japanese Patent Laid-Open No. 2-129065),
A dielectric ceramic composition containing a predetermined amount of CaTiO ₃ in MgTiO ₃ and TiO ₂ (Japanese Patent Application Laid-Open No. Sho 52-118599) is known.

[0003]

However, in the former dielectric ceramic composition, Nd ₂ O ₃ , La ₂ O ₃ , PbO, Zn
In addition to containing many other components such as O, Qu cannot always be said to be a large value. In the latter dielectric porcelain composition, TiO
₂ as an essential component, and the mixing amount of CaTiO ₃ is 3 to
In the range of 10% by weight, there was a problem that τf greatly changed from +87 to -100, and it was difficult to adjust (especially fine adjustment) to a small value near 0.

[0004] The present invention is to solve the above problems, while maintaining Qu and epsilon _r a practical characteristic range, tau
It is an object of the present invention to provide a dielectric ceramic composition capable of arbitrarily and precisely controlling f to be close to zero or to desired values on the plus side and the minus side with zero as a center.

[0005]

Means for Solving the Problems The present inventors have found that, in the dielectric ceramic composition, while maintaining high Qu and epsilon _r, tau
As a result of various studies on compositions that can make f close to zero and have stable quality even when the firing temperature is changed, it was found that this defect can be solved by adjusting the amount of Co ₂ O ₃ added. Thus, the present invention has been completed.

That is, the dielectric ceramic composition of the present invention comprises xM
gTiO ₃ · (1-x) CaTiO ₃ [provided that 0.93
≦ x ≦ 0.95] as a main component, and 3 to 12 parts by weight based on 100 parts by weight of the above xMgTiO _3. (1-x) CaTiO ₃ (hereinafter, 3 to 12 parts for convenience)
% By weight. Characterized in that the Co ₂ O ₃₎ of was contained added. If x is smaller than 0.93, τf takes a large positive value and Qu decreases. Conversely, if it exceeds 0.95, τf takes a large negative value, which is not preferable. When the addition amount of Co ₂ O ₃ is less than 3% by weight, τ _f increases to the plus side, and
If it exceeds 12% by weight, τ _f becomes large on the minus side,
In addition, Qu becomes undesirably small. On the other hand, when the content is 3 to 12% by weight, τ _f can be set to a value close to zero while keeping Qu and ε _r within a practical range without much lowering. And CaTiO ₃
The mixing ratio (1-x) as increases of, Qu decreases, epsilon _r increases, .tau.f tends toward the negative value to a positive direction (Table 1). Also, Co ₂ O ₃
Increases, the Qu tends to decrease (FIG. 1), the ε _r does not change much, but tends to slightly decrease (FIG. 2), and the τf tends to the minus direction (FIG. 3). ), The sintering density tends to increase (FIG. 4).

In particular, when the amount of Co ₂ O ₃ added is 6% by weight.
And when fired at 1350-1450 ° C., as shown in Table 1 and FIGS.
3970, τf is −0.74 to −0.03 ppm / ° C.,
The ε _r is 20.4 to 20.8, and the sintered density is 3.83 to 3.
It is 89 g / cm ³ , and even when fired in a wide temperature range of 100 ° C., the dispersion of each performance is small and excellent performance is shown. In particular, τf has an extremely small absolute value near 0 ppm / ° C. and is about 0.5 (pp
m / ° C.) / 1% by weight Co ₂ O ₃ , very preferably τ
Fine adjustment of _f is also very easy. From the above, Co ₂ O ₃
And the appropriate and wide firing temperature range,
These performances are excellent and balanced, and fine adjustment of τ _f is easy and stable.

[0008]

The present invention will be described below in detail with reference to examples. MgO powder (purity; 99.4%), C as CaO
aCO ₃ powder (purity; 99%), TiO ₂ powder (purity;
99.98%), Co ₂ O ₃ powder (purity; 99.1%)
As a starting material, as shown in Tables 1 to 3 and FIGS. 1 to 8, the composition formula xMgTiO _3. (1-x) CaTiO ₃ +
yCo ₂ O ₃ % by weight [xMgTiO _3. (1-x) Ca
100 parts by weight of TiO ₃ means y parts by weight of Co ₂ O ₃ . A predetermined amount (about 500 g in total) was weighed and mixed so that each of x and y in the above formulas was changed. still,
Table 1 shows that CaTiO ₃ (1-x) without containing Co ₂ O ₃
Table 2 shows that a certain amount of CaTiO 2 was added.
_{3 When} (1-x) is added (composed), Co ₂
That the amount of O ₃ is varied, Table 3 a certain amount of Co ₂
In the case where O ₃ is added, the amount of CaTiO ₃ added is changed.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

Thereafter, dry mixing (20)
-30 minutes) and primary pulverization, and then calcined in an air atmosphere at a temperature of 1100 ° C for 2 hours. Next, an appropriate amount of an organic binder (29 g) and water (300 to 300 g) were added to the calcined powder.
400 g), and with an alumina ball of 20 mmφ, 9
Grinding was performed at 0 rpm for 23 hours. Thereafter, granulation is performed by vacuum freeze-drying (about 0.4 Torr, 40 to 50 ° C., about 20 hours), and 1 ton / cm ² is obtained using the granulated raw material.
At a pressing pressure of 19 mmφ × 11 mmt (thickness). Next, the molded body was heated at 500 ° C.
Was degreased with time, then, at each temperature in the range of 1,325-1,450 ° C., and calcined for 4 hours, and finally the two end faces about 16 mm
Polished into a cylindrical shape of φ × 8 mmt (thickness), and the dielectric samples (Nos. 1 to 12 in Table 1, Nos. 1 to 24 in Table 2, and Table 3)
No. 25, 26).

Then, for each sample, ε _r , ε _r , by the parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MODE), etc.
Qu and τf, and the sintered density were measured by Archimedes' method. Here, τ _f is measured in a temperature range of 20 ° C. to 80 ° C., and τ _f = [(f (80 ° C.) − F (20 ° C.)] / [F (2
0 ° C.) × ΔT]. This ΔT is 80 ° C-20 ° C
= 60 ° C. The resonance frequency is 6 GHz. The results are shown in Tables 1 to 3 and FIGS. In addition, as an example, 0.94MgTiO ₃ · 0.06CaTiO ₃
A porcelain composition of ₃ , 6 or 12% by weight Co ₂ O ₃ (14
FIG. 1 shows the results of X-ray diffraction for
0 is shown.

According to these results, xMgTiO _3.
(1-x) Qu value (1-x) is large CaTiO ₃ is tends to be low, the τf and epsilon _r conversely tends to increase on the plus side. The sintering density tends to increase as the firing temperature increases. Also, although ε _r does not change much by the addition of Co ₂ O ₃ , Qu and τ
f tends to be small, and the sintered density tends to increase. In particular, when (1-x) is 0.06 and the added amount of Co ₂ O ₃ is 6% by weight, for example, when the firing temperature is 1375 ° C., τf is −0.10 ppm / ° C. and ε _r is 2
0.82, Qu is 3870, and sintering density is 3.894, showing particularly excellent performance balance. When the firing temperature is 1350 to 1450 ° C., Qu, ε _r and τ
_f has very small variation (for example,
When Co ₂ O _{3 is} 6% by weight, 3780 to 397
0, 20.35 to 20.82, -0.03 to -0.74
ppm / ° C.), and the desired quality can be stably obtained. Furthermore, even if the addition amount of Co ₂ O ₃ is changed,
Qu, ε _r and τ _f have extremely small variations (for example, when the firing temperature is 1400 ° C.,
3700-3900, 20.43-21.00, -0.
05 to -3.13 ppm / ° C). Therefore, even when the amount of Co ₂ O ₃ added and the sintering temperature are changed, products with extremely stable quality can be manufactured. In particular, fine adjustment of τf is extremely easy.

Further, according to the analysis method based on the presence or absence of the X-ray diffraction peak shown in FIG.
It contains O ₃ (○) and CaTiO ₃ (■), and the other peak is MgTi ₂ O ₄ (●), indicating that it does not contain a reaction product with Co ₂ O ₃ . Also, Co
_{As the} added amount of ₂ O ₃ increases, the relative peak intensity of MgTiO ₃ decreases, and the intensity of MgTi ₂ O ₄ increases. It is considered that the decrease in Qu is caused by a decrease in the amount of MgTiO ₃ .

Further, although not shown, according to the results of electron micrographs, the particle diameter increases as the firing temperature increases (1350 ° C .; 4.30 μm, 1400 ° C .; 5.32).
μm, 1450 ° C; 7.20 μm, both Intercept
Method). All fracture surface structures showed intragranular fracture.

The present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention according to the purpose and application. That is,
Various calcination conditions such as the calcination temperature and calcination conditions such as the calcination temperature can be selected. Also, the raw material to be CaO is the same as the above CaC.
In addition to O ₃ , peroxides, hydroxides, nitrates and the like can also be used. Similarly, other compounds that become oxides by heating can be used for other oxides.

[0018]

As described above, the dielectric porcelain composition of the present invention can be obtained by adjusting the amount of Co ₂ O ₃ while maintaining Qu and ε _r within a practical (high) characteristic range. ,
It is possible to make τf close to zero or arbitrarily control the desired value on the plus side and the minus side with zero as the center, and to stably adjust τf to around zero. Furthermore,
By adding Co ₂ O ₃ , a high-quality sintered body can be stably manufactured even when the firing temperature is varied in a wide temperature range, and fine adjustment of τf is extremely easy.

[Brief description of the drawings]

FIG. 1 is manufactured by firing at each firing temperature [0.
94MgTiO ₃ · 0.06CaTiO ₃ + (3~1
In ₂₎ Co 2 O ₃ wt%] ceramic composition, Co ₂ O
It is a graph which shows the relationship between ₃ quantity and Qu.

2] In the porcelain composition shown in FIG.
Is a graph showing the relationship between the weight%) Co ₂ O ₃ amount and epsilon _r.

FIG. 3 shows the porcelain composition shown in FIG.
4 is a graph showing the relationship between the amount of Co ₂ O ₃ and τf.

FIG. 4 shows the porcelain composition shown in FIG.
4 is a graph showing the relationship between the amount of Co ₂ O ₃ and the sintered density.

FIG. 5 [0.94MgTiO ₃ .0.06CaTiO
₃ is a graph showing the relationship between sintering temperature and Qu in a 3+ (3-12) wt% Co ₂ O ₃ ] porcelain composition.

In Figure 6 ceramic composition shown in FIG. 5 is a graph showing the relationship between firing temperature and epsilon _r.

FIG. 7 is a graph showing the relationship between the firing temperature and τf in the porcelain composition shown in FIG.

FIG. 8 is a graph showing a relationship between a sintering temperature and a sintering density in the porcelain composition shown in FIG.

9 is a graph showing the relationship between the firing temperature and the average particle size in the porcelain composition shown in FIG.

FIG. 10 [0.94MgTiO ₃ .0.06CaTi
₃ is a graph showing the results of X-ray diffraction of [O ₃ +3, 6, or 12% by weight Co ₂ O ₃ ] porcelain composition.

Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. xMgTiO _3. (1-x) CaTiO
₃ [However, a composition represented by 0.93 ≦ x ≦ 0.95] as a main component, and the above-mentioned xMgTiO _3. (1-x) C
Co 3-12 parts by weight per ATiO ₃ 100 parts by weight
A microwave dielectric porcelain composition comprising ₂ O ₃ added and contained.