JPH06260033A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition having a high dielectric constant, large no-load Q, and good stability of the temperature coefficient of resonance frequency. CONSTITUTION:A dielectric ceramic composition is made of barium, strontium; zinc, magnesium, niobium, and oxygen, and it is expressed by the composition formula: 3(Ba1-xSrx)).(Zn1-yMgy)O.Nb2O5 where 0.4<x<0.8, O<y<l.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition suitable as a dielectric resonator material. The dielectric ceramic composition of the present invention can be used not only as a dielectric resonator material but also as, for example, a microwave IC substrate, a dielectric adjusting rod, 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 has a large relative permittivity ε _r, excellent stability of the temperature coefficient τ _f of the resonance frequency and linearity of the temperature characteristic of the resonance frequency. It is required that the unloaded Q be large. As such a dielectric ceramic composition, T
It is known that the main component is iO ₂ , BaO—TiO _2, etc., but it is difficult to put it into practical use due to its large temperature coefficient and large dielectric loss in the microwave band.

Further, xBaO-yZnO-zNb ₂ O ₅
Of the dielectric ceramic composition of JP-A-53-35
453), (Ba _1-x Sr _x ) O.ZnO.yN
Proposal of dielectric ceramic composition of b ₂ O ₅ (Japanese Patent Publication No. 59-23)
045), 3BaO.xMgO. (1-x) Zn
Proposal of dielectric ceramic composition of O · Nb ₂ O ₅ (Japanese Patent Publication Sho 59)
However, in any case, sufficiently large ε _r and Q value are not obtained.

Further, Ba (Mg _1/3 Ta _2/3 ) O
₃ system, Ba (Zn _1/3 Ta _2/3 ) O ₃ system, Ba (Zn
Dielectric porcelain compositions having a perovskite type structure such as _1/3 Nb _2/3 ) O ₃ system are also known, but since these have a low relative dielectric constant, they are resonators in the 0.1-4 GHz band, for example. There is a problem that is too large.

[0005]

An object of the present invention is to provide a dielectric ceramic composition suitable as a dielectric resonator material, particularly as a dielectric resonator material used in the 0.1 to 5 GHz band. Another object of the present invention is to provide a dielectric ceramic composition having a high dielectric constant, a large Q, and a good stability of τ _f .

[0006]

Among the many constituent elements used in dielectric porcelain compositions, the inventors have identified a particular combination of barium, strontium, zinc, magnesium, niobium and oxygen. The present inventors have found that the above object can be achieved by the above porcelain composition and completed the present invention. The present invention provides a compositional formula, 3 (Ba _1-x Sr _x ) O. (Zn _1-y
Mg _y ) O · Nb ₂ O ₅ (wherein 0.4 <x <0.8,
0 <y <1. ) Relating to a dielectric ceramic composition comprising barium, strontium, zinc, magnesium, niobium and oxygen.

Since the dielectric ceramic composition of the present invention has a large relative permittivity, the resonator can be downsized and the unloaded Q also becomes large. Further, the temperature coefficient τ _f of the resonance frequency is small.
In the present invention, if the mole fraction of SrO is larger than 0.8 or smaller than 0.4, the temperature coefficient τ _{f of the} resonance frequency becomes large, so the mole fraction of SrO is limited to the above range. Further, when the MgO mole fraction is 0, the no-load Q is small, and when it is 1, the dielectric constant is small. Therefore, the MgO mole fraction is limited to the above range.

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, strontium carbonate, zinc oxide, magnesium oxide, and niobium oxide are wet-mixed in predetermined amounts with a solvent such as water or alcohol. Then, after removing water, alcohol, etc.,
It is crushed and calcined in an oxygen-containing gas atmosphere (eg, air atmosphere) at 1100 to 1300 ° C. for about 2 hours. The calcined product formed by this is crushed, mixed with an organic binder such as polyvinyl alcohol to homogenize, dried,
Pulverized and pressure molded (pressure 100-1000 kg / cm
² ) By firing this molded product at 1500 to 1650 ° C. in an oxygen-containing gas atmosphere such as air,
A dielectric ceramic composition represented by the above composition formula is obtained.

The thus-obtained dielectric ceramic composition is used as it is or by being processed into a suitable shape and size as required, so that a dielectric resonator, a dielectric substrate for microwave IC, a dielectric adjusting rod, etc. Can be used as a material for the dielectric resonator, and particularly excellent effects can be obtained when the dielectric resonator is used in the 0.1 to 5 GHz band.

Barium, strontium, zinc,
Raw materials for magnesium and niobium include BaCO ₃ and S
In addition to rCO ₃ , ZnO, MgO, Nb ₂ O _{5 and the} like, it is possible to use carbonates, hydroxides and the like which become oxides during firing.

[0011]

EXAMPLES The present invention will be described in more detail below with reference to Examples.
Explained. Example 1 Barium carbonate (BaCO₃) 1.2 mol powder, carbonic acid strike
Rontium (SrCO ₃) 1.8 mol powder, zinc oxide
(ZnO) powder 0.7 mol, magnesium oxide (Mg
O) powder 0.3 mol, niobium oxide (Nb₂O_Five) Powder
Place 1.0 mol in a ball mill with ethanol,
Wet mixed for hours. Remove this mixture from the ball mill
Then, evaporate the ethanol of the solvent and crush it with a crusher for 1 hour.
Crushed. The crushed product was calcined at 1200 ° C in an air atmosphere.
Then, crush with a crusher again for 1 hour, and_0.5Sr
_0.5) O ・ (Zn_0.7Mg_0.3) O ・ Nb₂O_FiveComposition of
A calcined powder consisting of Then, add an appropriate amount of po
Add the vinyl alcohol solution and mix evenly.
Molded into pellets with a diameter of 15 mmφ and a thickness of 5.5 mm
Induction of the present invention by firing and sintering at 1560 ° C for 2 hours in an ambient atmosphere.
An electric porcelain composition was obtained. The porcelain composition thus obtained
Measured by the dielectric resonance method after cutting to an appropriate size
And the resonance frequency f₀No load Q at (4-6 GHz)
And relative permittivity ε_rI asked. Also, the temperature of the resonance frequency
Dependence is measured in the range of -40 to 50 ℃, temperature
Coefficient τ_fI asked. The results are shown in Table 1.

Examples 2 to 10 Dielectric materials were prepared in the same manner as in Example 1 except that the mixing ratio of barium carbonate, strontium carbonate, zinc oxide, magnesium oxide and niobium oxide in Example 1 was changed as shown in Table 1. A porcelain composition was produced and the characteristics were measured as in Example 1.
The results are shown in Table 1. Those marked with * in the table are comparative examples outside the scope of the present invention.

[0013]

[Table 1]

[0014]

According to the present invention, a dielectric ceramic composition having a high dielectric constant, a large Q, and a good stability of τ _f can be obtained.

Claims (1)

[Claims] 1. A composition formula: 3 (Ba _1-x Sr _x ) O.
(Zn _1-y Mg _y ) O.Nb ₂ O ₅ (wherein 0.4 <x
<0.8 and 0 <y <1. ) Barium,
A dielectric ceramic composition comprising strontium, zinc, magnesium, niobium and oxygen.