JP3257147B2 - 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 dielectric ceramic composition suitable as a material for a dielectric resonator or the like. The dielectric ceramic composition of the present invention can be applied to, for example, a dielectric substrate for microwave IC, a dielectric adjustment rod, and the like, in addition to the dielectric resonator material.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a small and high-performance dielectric resonator has been demanded. Such dielectric ceramic compositions used in the dielectric resonator, the specific dielectric constant epsilon _r is large, it unloaded Q is large, also the stability is good like temperature coefficient tau _f of the resonant frequency Characteristics are required.

Heretofore, BaO-TiO ₂ based dielectric ceramic compositions have been known as dielectric resonators having excellent characteristics. For example, in Japanese Patent Application Laid-Open Nos. 56-102003 and 57-21010, BaO-TiO
_{2 -Nd 2 O 3 -Bi 2 O} 3 system, BaO-TiO ₂ -S
m ₂ O ₃ -Nd ₂ O ₃ based ceramic compositions have been proposed.
However, the characteristics are still insufficient, and there is room for improvement in the reproducibility of the electrical characteristics.

In the case where the material is used in various fields as a material for a dielectric resonator or the like, the temperature characteristic τ of the resonance frequency
_f is the problem and the relative dielectric constant epsilon _r and no additional Q is large, it has been demanded a dielectric ceramic composition having a more excellent temperature characteristic tau _f. In particular, since the temperature characteristic τ _f of the resonance frequency in the Ba—Ti system is +4 to +10 ppm / ° C. and is large on the positive side, the dielectric ceramic composition in which the temperature characteristic τ _f is controlled and shifted to the negative side is used. It has been demanded. In order to realize this, it has been attempted to add another element to the BaO-TiO ₂ system or to substitute it with another element. However, the relative dielectric constant is small, and the unloaded Q is still small. Was not enough.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dielectric ceramic composition having more excellent properties as a dielectric resonator material, especially a high dielectric constant, a large unloaded Q, and a temperature coefficient τ of the resonance frequency.
_An object of the present invention is to provide a dielectric ceramic composition having good stability of _f and capable of controlling τ _f from a negative side to a positive side.

[0006]

According to the present invention, there is provided a composition formula, x
BaO-y [(1-z) TiO ₂ .zM] -aMnO-
bSb ₂ O ₃ -cLa ₂ O ₃ (where M is ZrO ₂ , HfO ₂
Or at least one of SnO ₂ , and 0.1818
≦ x <0.2 , 0.8 ≦ y ≦ 0.8182, 0 <z ≦
0.1 and x + y = 1. Also, 0 <a ≦ 5,
0 <b ≦ 5, 0 ≦ c ≦ 5, where a, b and c are% by weight
It is. ), Barium, titanium, zirconium, hafnium, tin, manganese, antimony, lanthanum and oxygen.

[0007] The present invention relates to a method for preparing a specific amount of BaO, TiO._TwoThe lord
TiO2_TwoPart of ZrO _Two, HfO_TwoOr
SnO_TwoBy substituting at least one of
Therefore, it is possible to improve the difficulty of the conventional dielectric ceramic composition.
It is based on the knowledge that it can be cut.

In the present invention, the molar fraction x of BaO is greater than 0.2, or the molar fraction x of BaO is O.O. 1
If it is smaller than 818, the temperature coefficient τ _f of the resonance frequency increases, so that the molar fraction x of BaO is set in the above range. The dielectric constant epsilon _r is large, the unloaded Q is large,
Moreover, in order to control the temperature coefficient τ _f of the resonance frequency from the negative side to the positive side, the molar fraction x of BaO must be 0.1818 ≦
The range of x ≦ 0.19 is preferred.

[0009] When replacing TiO ₂ with at least one of ZrO ₂ , HfO _{2 and} SnO ₂ , if the replacement amount is excessively large, the no-load Q decreases and the temperature coefficient τ _{f of the} resonance frequency increases. , Z are set in the above range. The specific amount of TiO ₂ is changed to ZrO ₂ , HfO ₂ or S
By substituting at least one of nO ₂ , the temperature coefficient τ _f of the resonance frequency can be reduced, and the temperature coefficient τ _f can be controlled from the negative side to the positive side by the component composition ratio. Further, simultaneous addition of MnO and Sb ₂ O ₃
Alternatively, the Q value can be improved by simultaneous addition of MnO, Sb ₂ O ₃ and La ₂ O ₃ .

An example of a preferred method for producing the dielectric ceramic composition of the present invention will be described below. A predetermined amount of each starting material of barium carbonate, titanium oxide, zirconium oxide, hafnium oxide, tin oxide, manganese carbonate, antimony oxide, and lanthanum oxide is wet-mixed together with a solvent such as water or alcohol. Then, after removing water, alcohol, etc., pulverize,
900 ~ under an oxygen-containing gas atmosphere (for example, air atmosphere)
It is calcined at 1100 ° C. for about 5 hours. The calcined product thus formed is pulverized, and an organic binder such as polyvinyl alcohol is added and mixed to homogenize, dried, pulverized, and pressed (100 to 1000 kg / cm ² ). Thereafter, the molded article is fired at 1250 to 1420 ° C. in an oxygen-containing gas atmosphere such as air to obtain a dielectric ceramic composition represented by the above composition formula.

The dielectric ceramic composition thus obtained can be processed as it is or as necessary into an appropriate shape and size to obtain a dielectric resonator, a dielectric substrate for microwave IC, a dielectric adjusting rod. And the like. Particularly, when a dielectric resonator used in a microwave band is used, an excellent effect is exhibited.

In addition, barium, titanium and zirconium
As raw material, BaCO_Three, TiO _Two, ZrO_Two, Hf
O_Two, SnO_Two, MnCO_Three, Sb_TwoO_Three, La_TwoO_Three
Carbonate, nitric acid, etc.
Salts, hydroxides and the like can be used.

[0013]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Example 1 Barium carbonate (BaCO ₃ ) powder 0.1818 mol, titanium oxide (TiO ₂ ) powder 0.8141 mol, zirconium oxide (ZrO ₂ ) powder 0.0041 mol, manganese carbonate (MnCO ₃ ) powder 0.3 weight % And Sb ₂ O
₃ 0.7% by weight of the powder was put into a ball mill together with ethanol and wet-mixed for 10 hours. The mixture was taken out of the ball mill, the ethanol of the solvent was evaporated, and the mixture was pulverized for 1 hour using a crusher. The pulverized material was calcined at 1000 ° C. in an air atmosphere, and then pulverized again with a crusher for 1 hour to obtain a calcined powder.

Next, an appropriate amount of a polyvinyl alcohol solution was added to the calcined powder, and the mixture was uniformly mixed.
The resultant was molded into a disc-shaped pellet having a diameter of 5.5 mm and fired and sintered at 1380 ° C. for 2 hours in an air atmosphere to obtain a dielectric ceramic composition of the present invention. After the porcelain composition thus obtained was appropriately cut, it was measured by the dielectric resonance method, and the no-load Q and the relative permittivity ε _r at the resonance frequency f ₀ (2 to 6 GHz) were obtained. The temperature dependence of the resonance frequency was measured in the range of -40 to 50 ° C, and the temperature coefficient τ _f
I asked. Table 1 shows the results.

Examples 2 to 5 A dielectric ceramic composition was produced in the same manner as in Example 1 except that the mixing ratio of barium carbonate, titanium oxide and zirconium oxide was changed. And the electrical characteristics were measured. Table 1 shows the results.

Comparative Examples 1 to 5 Dielectric ceramic compositions were produced in the same manner as in Example 1 except that the amounts of starting materials used were changed, and the electrical characteristics were measured. Table 1 shows the results.

[0017]

[Table 1]

[0018]

[0019]

The dielectric porcelain composition of the present invention has an unloaded Q
In addition to having a large relative dielectric constant, the temperature coefficient of the resonance frequency is excellent in stability and the temperature coefficient can be controlled from the negative side to the positive side, so that it is suitable as a dielectric ceramic material. Further, using the dielectric porcelain composition of the present invention,
For example, when used as a microwave dielectric resonator, there is an advantage that the reliability of the receiver can be greatly improved and the receiver can be downsized.

Continuation of front page (56) References JP-A-4-300243 (JP, A) JP-A-2-239511 (JP, A) JP-A-58-223668 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01P 7/10

Claims (2)

(57) [Claims] 1. The composition formula, xBaO-y [(1-z) TiO
₂ · zM] -aMnO-bSb ₂ O ₃ -cLa ₂ O ₃ (wherein M is at least one of ZrO ₂ , HfO ₂ or SnO ₂ , and 0.1818 ≦ x <0.2 , 0.8 ≦ y ≦
0.8182, 0 <z ≦ 0.1, and x + y = 1. 0 <a ≦ 5, 0 <b ≦ 5, 0 ≦ c ≦ 5, where a, b and c are% by weight. A) a dielectric porcelain composition comprising barium, titanium, zirconium, hafnium, tin, manganese, antimony, lanthanum and oxygen. 2. The composition according to claim 1, wherein 0.1818 ≦ x ≦
2. The dielectric according to claim 1, wherein the dielectric constant is 0.19.
Porcelain composition.