JPH0855519A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition large in a dielectric constant epsilonr also a no-load Q value and moreover small in the temperature coefficient tauf of a resonance frequency. CONSTITUTION:A dielectric ceramic composition is composed of barium, titanium, neodymium, samarium, bismuth, and oxygen; and the main component of this composition is expressed as xBaO-yTiO2-zNd2O3-tSm2O3-wBi2O3 (in this formula, 0.1<=x<=0.2, 0.5<=y<=0.8, 0.01<=z<=0.2, 0.01<=t<=0.2, 0.005<=w<=0.05, and x+y+z+t+w=1). This dielectric ceramic composition contains glass power composed of PbO, ZnO, and B2O3 and CuO as a sub-component, and the content (a) (wt.%) of the sub-component glass power and that (b)(wt.%) of the CuO are 1<=a<=25 and 0.5<=b<=5 respectively.

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.

[0002]

2. Description of the Related Art In recent years, with the integration of microwave circuits, a compact and high-performance dielectric resonator is required. The dielectric ceramic composition used for such a dielectric resonator is required to have characteristics such as a large relative permittivity ε _r , a large unloaded Q, and a small temperature coefficient τ _f of the resonance frequency. Has been done.

As such a dielectric ceramic composition, Ba
Proposed O-TiO ₂ —Nd ₂ O ₃ based dielectric ceramic composition [Ber. Dt. Keram. Ges., 55 (1978) Nr. 7;
-35406 JP], or BaO-TiO ₂ -N
A d ₂ O ₃ -Bi ₂ O ₃ system (Japanese Patent Laid-Open No. 62-72558) has been proposed.

Recently, a laminated chip capacitor, a laminated dielectric resonator, etc. in which dielectric ceramic compositions are laminated have been developed, and the ceramic composition and internal electrodes are laminated by simultaneous firing. However, since the firing temperature of the dielectric ceramic composition is as high as 1300 ° C. to 1400 ° C., it is difficult to perform simultaneous firing with the internal electrodes, and in order to form a laminated structure, it can withstand high temperatures as an electrode material. It has been limited to materials such as palladium (Pd) and platinum (Pt). Therefore, inexpensive silver (Ag), silver-palladium (Ag-Pd), and copper (Cu) are used as the electrode material at 1200 ° C.
There is a demand for a dielectric ceramic composition that can be co-fired at the following low temperatures.

[0005]

It is an object of the present invention to have excellent characteristics as a material for a dielectric resonator or the like, in particular to have a high dielectric constant, a large no-load Q, and a small change in resonance frequency with temperature.
Moreover, it is to provide a dielectric ceramic composition having good sinterability even when fired at a low temperature.

[0006]

Means for Solving the problems] The present invention is a main component composition _{formula, xBaO-yTiO 2 -zNd 2 O} 3 -tSm 2
O ₃ -wBi ₂ O ₃ (wherein 0.1 ≦ x ≦ 0.2, 0.
5 ≦ y ≦ 0.8, 0.01 ≦ z ≦ 0.2, 0.01 ≦ t
≦ 0.2, 0.005 ≦ w ≦ 0.05, x + y + z + t
+ W = 1. ) Is a dielectric ceramic composition composed of barium, titanium, neodymium, samarium, bismuth, and oxygen, and is a glass powder and CuO composed of PbO, ZnO, and B ₂ O ₃ as auxiliary components.
And the content a of the accessory glass powder with respect to the main component a
(% By weight) 1 ≦ a ≦ 25, CuO content b (% by weight) 0.5 ≦ b ≦ 5, relates to a dielectric ceramic composition.

According to the invention, the composition formula xBaO-yTi
_{O 2 -zNd 2 O 3 -tSm 2} O 3 -wBi PbO as a sub-component in the dielectric ceramic composition represented by ₂ O _3, ZnO
And a glass powder composed of B ₂ O ₃ and Cu
By containing O, it is possible to obtain a dielectric ceramic composition which can be sintered at a low temperature, has a high dielectric constant, has a large unloaded Q, and has a small temperature change in the resonance frequency.

In the present invention, when the molar fraction of BaO is excessively large, resonance does not occur, and when it is excessively small, the dielectric constant and the no-load Q become small. When the mole fraction of TiO ₂ is too large, the temperature coefficient of the resonance frequency becomes large, and when it is too small, the dielectric constant becomes small. When the mole fraction of Nd ₂ O ₃ is excessively large, the dielectric constant and unloaded Q become small, and when it is excessively small,
Dielectric constant decreases. When the mole fraction of Sm ₂ O ₃ is too large, the dielectric constant becomes small, and when it is too small, the no-load Q becomes small. When the mole fraction of Bi ₂ O ₃ is excessively large, the dielectric constant and the no-load Q become small, and when it is excessively small, the temperature coefficient of the resonance frequency becomes large.

In the present invention, the content a (% by weight) of the glass powder composed of the subordinate components PbO, ZnO and B ₂ O ₃ and the content b of CuO relative to the main component.
If (wt%) is too large, it will not resonate,
Further, when the content of glass powder composed of PbO, ZnO and B ₂ O ₃ and CuO is too small or zero, low temperature firing at 1200 ° C. or lower becomes difficult. Therefore, the subcomponents PbO, ZnO and B ₂ O ₃
The content a of the glass powder and the content b of CuO composed of are set in the above ranges. In the accessory glass powder, the composition ratios of PbO, ZnO and B ₂ O ₃ are not particularly limited, but when the content of ZnO is excessively large, the softening point of the glass rises and low temperature firing by adding glass powder is difficult. Therefore, the content of ZnO in the glass powder is preferably 50% by weight or less.

In the present invention, N is used as the third component.
b₂O_Five, MnO, Al₂O₃And ZnO
The inclusion of at least one kind causes the temperature dependence of the resonance frequency.
Number τ _fThe absolute value of can be further reduced. Main character
The content c (% by weight) of the third component is too large.
Temperature coefficient τ of resonance frequency_fWill grow
And the content c is 0 ≦ c ≦ 2, preferably 0.1 ≦ c
≦ 2.

An example of a suitable method for producing the dielectric ceramic composition of the present invention will be described below. Starting materials of barium carbonate, titanium oxide, neodymium oxide, samarium oxide, and bismuth oxide are wet-mixed in predetermined amounts with a solvent such as water or alcohol. Then, after removing water, alcohol, etc., the product is pulverized and placed under an oxygen-containing gas atmosphere (for example, an air atmosphere) to obtain 1
Calcination is performed at 000 to 1200 ° C for about 1 to 5 hours. A glass powder composed of the calcined powder thus obtained and the subcomponents PbO, ZnO and B ₂ O ₃ , the subcomponent CuO,
And Nb ₂ O ₅ , MnO, Al ₂ O as the third component
_At least one or more of ₃ and ZnO is wet-mixed with a solvent such as alcohol. Then, after removing water, alcohol, etc., it is pulverized. Further, it is mixed with an organic binder such as polyvinyl alcohol to make it homogeneous,
Drying, crushing, pressure molding (pressure 100-1000Kg / c
m ² ). The dielectric ceramic composition represented by the above composition formula is obtained by firing the obtained molded product in an oxygen-containing gas atmosphere such as air at 850 ° C to 1100 ° C.

The dielectric porcelain composition thus obtained is processed into a suitable shape and size as required, or by sheet molding by a doctor blade method or the like and lamination by a sheet and an electrode. It can be used as a material for a dielectric resonator, a dielectric substrate, a laminated element and the like.

Barium, titanium, neodymium, summer
Lithium, Bismuth, Lead, Zinc, Boron, Copper, Niobium, Ma
BaCO is used as the raw material for gangan and aluminum.₃, T
iO ₂, Nd₂O₃, Sm₂O₃, Bi₂O₃, Pb
O, ZnO, B₂O₃, CuO, Nb₂O_Five, MnO,
Al₂O₃In addition to nitrates and hydroxides that become oxides during firing
Compounds and the like can be used.

[0014]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. Example 1 Barium carbonate powder (BaCO ₃ ) 0.15 mol, titanium oxide powder (TiO ₂ ) 0.675 mol, neodymium oxide powder (Nd ₂ O ₃ ) 0.13 mol, samarium oxide powder (Sm ₂ O) ₃ ) 0.02 mol, bismuth oxide powder (Bi
0.025 mol of ₂ O ₃ ) was put in a ball mill together with ethanol and wet-mixed for 12 hours. The solution was desolvated, pulverized, and calcined at 1100 ° C. in an air atmosphere. In addition, lead oxide (PbO) 84 wt%, boron oxide (B ₂ O ₃ ) 9 wt
% And zinc oxide (ZnO) 7 wt%, a glass powder A was prepared by a conventional method. The calcined product obtained above had glass powder A3 wt% composed of PbO, ZnO and B ₂ O ₃ and copper oxide powder (CuO) 1.
Add wt% and put in a ball mill with ethanol, 1
Wet mixed for 2 hours. After desolvating the solution, it is pulverized, and an appropriate amount of polyvinyl alcohol solution is added to the pulverized product and dried,
The pellet was molded into a pellet having a diameter of 12 mmφ and a thickness of 4 mmt and fired at 1150 ° C. for 2 hours in an air atmosphere.

The porcelain composition thus obtained has a diameter of 7 mm.
After processing into a size of φ and a thickness of about 3 mmt, measurement was performed by the dielectric resonance method, and the unloaded Q at the resonance frequency (3 to 5 GHz), the relative permittivity, and the temperature coefficient of the resonance frequency were obtained. The results are shown in Table 2.

Examples 2 to 14 and Comparative Examples 1 to 19 Barium carbonate, titanium oxide, neodymium oxide of Example 1
The mixing ratio of samarium oxide and bismuth oxide and the kind of glass powder composed of PbO, ZnO and B ₂ O ₃ which are the accessory components (glass powder B: PbO 85 wt%,
ZnO 8 wt%, B ₂ O ₃ 7 wt%) and its addition amount, the addition amount of the auxiliary component CuO and the addition amount of the third component are shown in Table 1.
A dielectric porcelain composition was produced in the same manner as in Example 1 except that the description was changed, and the characteristics were measured. The results are shown in Table 2.
Shown in

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

According to the present invention, it is possible to provide a dielectric ceramic composition having a large relative permittivity ε _r , a large unloaded Q value, and a small temperature coefficient τ _f of the resonance frequency. In addition, low temperature sintering is possible, and Ag, Ag-P
It is possible to provide a dielectric porcelain composition which can be laminated by using d, Cu or the like as an internal electrode.

Claims (1)

[Claims] 1. The main component is a composition formula, xBaO-yTiO.
_{2 -zNd 2 O 3 -tSm 2 O} 3 -wBi 2 O 3 ( where, 0.1 ≦ x ≦ 0.2,0.5 ≦ y ≦ 0.8,0.0
1 ≦ z ≦ 0.2, 0.01 ≦ t ≦ 0.2, 0.005 ≦
w ≦ 0.05 and x + y + z + t + w = 1. ) Is a dielectric porcelain composition consisting of barium, titanium, neodymium, samarium, bismuth and oxygen, and contains glass powder and CuO composed of PbO, ZnO and B ₂ O ₃ as accessory components, The content a (% by weight) of the glass powder as a subcomponent with respect to the main component is 1 ≦ a ≦ 2.
5. The dielectric ceramic composition, wherein the CuO content b (% by weight) is 0.5 ≦ b ≦ 5.