JP3212704B2 - Microwave dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave dielectric porcelain composition, and more particularly, to a temperature coefficient of resonance frequency (hereinafter referred to as "Qu") while maintaining a high value of unloaded Q (hereinafter referred to simply as "Qu"). Hereinafter, simply referred to as τf) can be made close to zero, and by further adjusting the mixing ratio of CaTiO ₃ , τf can be arbitrarily controlled to be a plus side and a minus side with zero as a center. The present invention relates to a microwave dielectric porcelain composition having high quality even when baked at a low temperature by the addition of water. 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, τf greatly changes from +87 to -100, and a small value near 0 has a problem that adjustment is difficult.

[0004] The present invention is intended to solve the above problems, by adjusting the mixing ratio of CaTiO ₃ and ZnO, while maintaining a practical characteristic range epsilon _r and Qu, close the τf to zero Alternatively, it can be arbitrarily and stably controlled to a desired value on the plus side and the minus side with zero as the center. Further, even if firing is performed at a low temperature by adding ZnO or the firing temperature fluctuates, high quality can be obtained. It is an object of the present invention to provide a dielectric ceramic composition comprising the same.

[0005]

Means for Solving the Problems The present inventor has proposed a dielectric ceramic composition which can make τf close to zero while maintaining a high Qu, and has a stable quality even when the firing temperature is changed. As a result of various investigations, CaTi
The inventors have found that this disadvantage can be solved by adjusting the proportions of O ₃ and ZnO added, and have completed the present invention.

That is, the dielectric ceramic composition of the present invention comprises xM
gTiO ₃ · (1-x) CaTiO ₃ [provided that 0.925
≦ x ≦ 0.950 as a main component a composition represented by], to which the _{xMgTiO 3 · (1-x)} CaTiO 3 100
3 to 9 parts by weight of ZnO is added to and contained by weight.
Qu at vibration frequency 6 GHz is 3330-4390,
εr is 19 to 22 and τf is −17 to +23 ppm
/ ° C. If x is smaller than 0.925, τf takes a large positive value and Qu decreases. Conversely, if it exceeds 0.950, τf takes a large negative value, which is not preferable. In particular, when x is 0.935 to 0.945 and the amount of ZnO added is 6% by weight, Qu is 3900 to 4100, τf is -5 to +5 (ppm / ° C.), and ε _r is 21. This is preferable because high quality can be ensured even when fired at a low temperature and stability against the firing temperature is exhibited.

Incidentally, as the mixing ratio of CaTiO ₃ increases, τf changes from a negative value to a positive direction (FIG. 3),
_r tends to increase (FIG. 2), while Qu tends to decrease (FIG. 1). Further, as shown in FIG. 7, by adding ZnO, a sintered body having a high density can be manufactured even when firing is performed at a low temperature (for example, 1325 to 1350 ° C.). Even if fired)
Stable quality can be obtained (FIGS. 4-1)
1). As described above, in the above-mentioned appropriate mixing range of CaTiO ₃ and ZnO, the performance is balanced and the quality is 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%) and ZnO powder (purity: 99.5%) as starting materials, and as shown in FIGS.
TiO ₃ · (1-x) CaTiO ₃ + y wt% ZnO
[XMnTiO ₃ · (1-x) means 100 parts by weight of ZnOy with respect to 100 parts by weight of CaTiO ₃ . ] So that each of x and y has a changed composition.
0 g) were weighed and mixed. Then, after performing dry mixing (20 to 30 minutes) and primary pulverization with a mixer, the mixture was calcined at 1100 ° C. for 2 hours in an air atmosphere. Next, an appropriate amount of an organic binder (29 g) and water (300 to 400 g) were added to the calcined powder, and the powder was ground with a 20 mmφ alumina ball at 90 rpm for 23 hours. Then, vacuum freeze drying (about 0.4 Torr, 40-50 ° C., about 20
Time), and the granulated material is used for 10
19mmφ × 11mmt at a press pressure of 00kg / cm ²
(Thickness).

Next, the compact is heated at 500 ° C.
Degreasing at time, then 1300-142 shown in each figure
Baking at each temperature in the range of 5 ° C. for 4 hours, and finally polishing both end surfaces into a cylindrical shape of about 16 mmφ × 8 mmt (thickness)
A dielectric sample was used. Then, for each sample, a parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MODE) is used.
ε _r (relative permittivity), Qu and τf, and the sintered density were measured by Archimedes' method. The resonance frequency is 6GH
z. These results are shown in FIGS. Also,
As an example, 0.95MgTiO ₃ · 0.05CaTi
FIG. 12 shows the result of X-ray diffraction in the case of O ₃ (0.95 MgT
against iO ₃ · 0.05CaTiO ₃ 6% by weight of Zn
O-containing, baked at 1300 ° C. for 4 hours), FIG. 13 (ZnO
And calcined at 1360 ° C. for 4 hours).

According to these results, xMgTiO _3.
(1-x) Qu value x is small 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, but becomes flat with respect to the firing temperature when the amount of ZnO added increases. Firing temperature is 1350-1425
In ° C., when x is in the range of 0.925 to 0.950,
τf is + 23~-17, ε _r is 19~22, Qu 33
It is preferable to show a practical characteristic range of 30 to 4390. In particular, when x is 0.940 and the amount of ZnO added is 6% by weight, for example, when the firing temperature is 1350 ° C. and 1375 ° C., as shown in FIGS.
1 ppm / ° C., ε _r is about 21, and Qu is about 4000, showing a particularly excellent performance balance. Further, with respect to τf, since the rate of change with respect to the firing temperature is low, it is easy to adjust a small value near 0. On the other hand, when CaTiO ₃ is not contained, ε _r is small although Qu value is large, and τ
f becomes extremely small on the minus side as −25 to −44, which is not preferable.

According to the analysis method based on the presence or absence of the X-ray diffraction peak shown in FIG.
O ₃ (○, partially including ZnTiO ₃ ) and CaTiO ₃
(●), and the other peaks were Mg ₂ TiO
₄ (△, partially including ZnTiO ₄ ), MgO,
This indicates that CaO and TiO ₂ are not contained.
FIG. 13 shows a case where ZnO is not included, and in this case, it is composed of MgTiO ₃ (○) and CaTiO ₃ (●), and again MgO, CaO, Ti
It shows that it does not contain O ₂ .

Further, although not shown, according to the results of electron micrographs, the particle diameter increases as the firing temperature increases (1300 ° C .; 3.1 μm, 1350 ° C .; 7.2 μm).
m, 1400 ° C .; 12.8 μm, all measured by the Intercept method), and the number of pores decreased, indicating that densification was completed at 1400 ° C. The fracture surface is 1300 ° C
At 1,350 ° C. or more, intragranular fracture was exhibited.

The present invention is not limited to the specific embodiments described above, but can 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.

[0014]

As it is evident from the foregoing description, the dielectric ceramic composition of the present invention, while maintaining Qu and epsilon _r practical (high) characteristic range, by adjusting the mixing ratio of CaTiO _3, .tau.f Can be controlled to a desired value on the plus side and the minus side with zero as the center, and τf can be stably adjusted to around zero. Furthermore, by adding ZnO, a sintered body having a high density and a high quality can be obtained even when the firing temperature is variously changed (or even when fired at a low temperature). Therefore, the mixing ratio of CaTiO ₃ and ZnO can be changed according to the purpose.

[Brief description of the drawings]

FIG. 1 [xMgT manufactured at a firing temperature of 1350 ° C.
6 is a graph showing the relationship between x and Qu in an iO _3. (1-x) CaTiO ₃ +6 wt% ZnO] porcelain composition.

In Figure 2 ceramic composition shown in FIG. 1 is a graph showing the relationship between x and epsilon _r.

FIG. 3 is a graph showing the relationship between x and τf in the porcelain composition shown in FIG.

FIG. 4 is manufactured by firing at each firing temperature [0.
_{94MgTiO 3 · 0.06CaTiO 3 + (0~9} )
2 is a graph showing the relationship between the amount of ZnO and Qu in a (% by weight ZnO) porcelain composition.

In Figure 5 ceramic composition shown in FIG. 4 is a graph showing the relationship between the amount of ZnO and epsilon _r.

6 is a graph showing the relationship between the amount of ZnO and τ _f in the porcelain composition shown in FIG.

FIG. 7 is a graph showing the relationship between the amount of ZnO and the sintered density in the porcelain composition shown in FIG.

FIG. 8 [0.94MgTiO ₃ .0.06CaTiO
₃ is a graph showing the relationship between firing temperature and Qu in a 3+ (0-9) wt% ZnO] porcelain composition.

In ceramic composition shown in FIG. 9 8 is a graph showing the relationship between firing temperature and epsilon _r.

FIG. 10 is a graph showing the relationship between the firing temperature and τf in the porcelain composition shown in FIG.

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

FIG. 12 [0.95MgTiO ₃ .0.05CaTi
₃ is a graph showing an X-ray diffraction result of a [O ₃ +6 wt% ZnO] porcelain composition.

FIG. 13: 0.95MgTiO ₃ .0.05CaTiO
₃ is a graph showing an X-ray diffraction result of a _three- porcelain composition.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field 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 0.925 ≦ x ≦ 0.950] as a main component, and the composition represented by the above xMgTiO _3. (1-
x) ₃ to 9 parts by weight of ZnO added to 100 parts by weight of CaTiO _{3, and} Qu at a resonance frequency of 6 GHz
Is 3330-4390, εr is 19-22, and τf
Is from −17 to +23 ppm / ° C. in a microwave dielectric porcelain composition.