JP3100182B2 - Microwave dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a microwave dielectric ceramic composition and, more particularly, the temperature coefficient of resonant frequency (hereinafter, simply referred .tau.f.) Can be brought close to zero, and TiO ₂ / By adjusting the molar ratio of BaO and the added amount of Ta ₂ O ₅ , τf can be arbitrarily controlled to a plus side and a minus side with zero as a center. INDUSTRIAL APPLICABILITY The present invention is used in a microwave region for impedance matching of a dielectric resonator, a microwave integrated circuit board, various microwave circuits, and the like.

[0002]

2. Description of the Related Art Conventional microwave dielectric ceramic compositions (hereinafter simply referred to as dielectric ceramic compositions) include Ba.
O-4TiO ₂ ceramic composition and the like are known.

[0003]

THE INVENTION Problems to be Solved point, however, the conventional of the dielectric ceramic composition, a dielectric constant (hereinafter, simply epsilon _r that.) High, unloaded Q (hereinafter, simply referred to. Qu) is large , Τf are relatively large, and thus lack stability.

The present invention overcomes the above-mentioned disadvantages, and it is possible to reduce τf to a small value centered at zero by adjusting the molar ratio of TiO ₂ / BaO and the amount of Ta ₂ O ₅ added. It is another object of the present invention to provide a dielectric ceramic composition capable of arbitrarily controlling τf 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 proposed BaO.
As a result of various investigations on the composition for bringing τf close to zero in the xTiO ₂ -based dielectric porcelain composition,
The inventors have found that this disadvantage can be solved by adjusting the molar ratio of ₂ / BaO and the amount of Ta ₂ O ₅ added, and have completed the present invention. That is, the dielectric porcelain composition of the present invention is composed of barium oxide and titanium oxide, and when its composition formula is represented by BaO.xTiO ₂ , x is in the range of 3.7 ≦ x ≦ 4.2. As a main component, and Ta ₂ O ₅ as a sub component with respect to 100 parts by weight of the main component.
3-10 parts by weight (hereinafter, simply referred to as% by weight.) Ri Na by containing additive in a range of, characterized in that it does not contain ZnO.

[0006]

The present invention will be described in detail with reference to the following examples. (1) Preparation of each sample BaCO ₃ powder and TiO ₂ powder having a purity of 99.9% were prepared in predetermined amounts according to the respective compositions, and further, Ta shown in Tables 1, 2 and 3 was used.
A predetermined amount (3, 6, 10% by weight) of ₂ O ₅ powder was weighed and mixed. Then, after performing dry mixing and primary pulverization using an Erich mixer, the mixture was calcined in an air atmosphere at a temperature of 1100 ° C. for 2 hours. Next, an appropriate amount of an organic binder and ion-exchanged water (260 to 500 g) are added to the calcined powder, and the mixture is subjected to secondary pulverization with a 20 mmφ alumina ball, and then granulated by spray drying.
19mmφ × 8mmt (thickness) at a press pressure of g / cm ²
Into a disk shape. Next, this molded body is placed in the air at 125
Bake for 4 hours at a temperature of 0 ° C to 1325 ° C.
It was polished into a disk shape of 6 mmφ × 6 mmt (thickness) to obtain dielectric samples (Nos. 1 to 33). Then, for each sample, a parallel conductor plate type dielectric cylinder resonator method (TE ₀₁₁ MOD
According to E), ε _r , Qu value and τf, and the sintered density were measured. Note that the resonance frequency is 4.5 GHz.

(2) Performance Evaluation The characteristics of each of the above dielectric samples were examined, and the results are shown in Tables 1, 2, and 3 and FIGS. The base material in Table 1 is Ba.
O-3.7TiO ₂ , the base material in Table 2 is BaO-4Ti
O ₂ , the base material in Table 3 is BaO-4.18TiO ₂ .

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

[Table 3]

[0011] According to these results, TiO ₂ / BaO
Are 3.7, 4.0 and 4.18, Ta is
_As the addition amount of ₂ O ₅ increases, τf changes from a positive value to a negative direction. In particular, when the values are 3.7 and 4.0, the tendency is remarkable, and the value goes beyond 0 and moves in the negative direction. Although the Qu value was low overall, the sample No. 104 except for 5, 8, 19 and 25
0 to 2830, which is in a sufficiently practical range. The reason for this low Qu value is that BaTi ₄ O ₉ is Ta
_{This is} probably due to the decrease due to the reaction with ₂ O ₅ . Also, ε
_{r is} also 16.0-38.0 in the range where measurement was possible.
It can be said that this is also within a sufficiently practical range. In addition, the sintering density also shows 3.20 to 4.60 g / cm ³ , which means that it is sufficiently dense. It should be noted that when the sintering density is low, ε _r also tends to be small, and the reason for the low ε _r is considered to be insufficient densification.

Further, according to Table 1 (X = 3.7), 125
According to Table 2 (X = 4.0), firing temperature of 1275 to 1300 ° C., Table 3 (X = 4.1)
According to 8), a sintered body having stable performance was obtained at each firing temperature of 1300 ° C. On the other hand, when the addition amount of Ta ₂ O ₅ is 6 to 10% by weight, τ _f is preferably close to 0, and is particularly preferable in FIGS. Tend. Moreover, according to Tables 1 and 2, the amount of Ta ₂ O ₅ added was 3% by weight and 10% by weight.
In the case of, measurement of the characteristics may not be possible. Further, T
If the amount of a ₂ O ₅ becomes large, there is a tendency that the sintered density is reduced. Therefore, when the added amount of Ta ₂ O ₅ is about 6% by weight, that is, 4 to 8% by weight, a τ _f is small, a sintered density is large and a stable sintered body can be manufactured, which is very practical. It is.

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. The raw material to be BaO is also BaC
In addition to O ₃ , peroxides, hydroxides, nitrates and the like can also be used.

[0014]

As is evident from the foregoing description, the dielectric ceramic composition of the present _invention, the molar ratio of TiO 2 / BaO and from 3.7 to 4.2, and and the addition amount of Ta ₂ O ₅ 3 to 10 By increasing or decreasing the weight% range, τf is decreased in a negative direction from a large positive value while maintaining ε _r and Qu in a practical characteristic range. Further, the dielectric ceramic composition of the present invention can arbitrarily control τf to a desired value on the plus side and the minus side centering on zero by adjusting the molar ratio of TiO ₂ / BaO and the amount of Ta ₂ O ₅ added. It was done. Therefore, the molar ratio of TiO ₂ / BaO and the addition ratio of Ta ₂ O ₅ can be changed according to the purpose.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of Ta ₂ O ₅ added and τf when the firing temperature is changed in a base material BaO-3.7TiO ₂ .

FIG. 2 is a graph showing the relationship between the amount of Ta ₂ O ₅ added and τf when the firing temperature is changed in a base material BaO-4.0TiO ₂ .

FIG. 3 is a graph showing the relationship between the amount of Ta ₂ O ₅ added and τf when the firing temperature is changed in a base material BaO-4.18TiO ₂ .

──────────────────────────────────────────────────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. It comprises barium oxide and titanium oxide,
When the composition formula is represented by BaO.xTiO ₂ , the composition in which x is in the range of 3.7 ≦ x ≦ 4.2 is the main component, and Ta ₂ O ₅ is added as an auxiliary component to 100 parts by weight of the main component. On the other hand,
3-10 added is contained in the range of parts by Ri name and, ZnO
A microwave dielectric porcelain composition characterized by not containing any .