JPH07114824A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition suitable for a dielectric resonance material in which dielectric constant epsilonr is large, no load Q is large, and temperature coefficient of resonance frequency tauf is small. CONSTITUTION:A dielectric ceramic composition is represented by the composition formula of AxBiYTizO15+M, wherein A shows at least one element selected from the group comprising Ca, Sr, Ba, La, and Pb, and X, Y, Z and in the range of 0.5<=X<=1.5, 3.0<=Y<=5.0, and 3.5<=Z<=4.5.

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 ceramic or the like. In addition to the dielectric resonator material, the dielectric ceramic composition of the present invention is also applied to, for example, a microwave IC dielectric substrate, a dielectric resonator rod, and 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 ), and
It is required that the stability of the temperature coefficient (τ _f ) of the resonance frequency and the linearity of the temperature characteristic of the resonance frequency be excellent and that the no-load Q be large.

As such a dielectric porcelain composition, a composition containing TiO ₂ , MgO-CaO-TiO ₂ or the like as a main component is conventionally known, but the former has a large temperature coefficient and the latter has a relative dielectric constant. There is a problem that is small.

[0004]

An object of the present invention is to provide a dielectric ceramic composition having excellent characteristics as a microwave dielectric material, particularly a dielectric material having a high dielectric constant, a large unloaded Q, and a small change in resonance frequency with temperature. To provide a porcelain composition.

[0005]

The present invention provides a composition formula, A
_X Bi _Y Ti _Z O _{15 + M} (In the formula, A is Ca, Sr, Ba,
At least one selected from the group consisting of La and Pb is shown. ) Is a dielectric porcelain composition represented by
X, Y and Z are 0.5 ≦ X ≦ 1.5 and 3.
The present invention relates to a dielectric ceramic composition in the range of 0 ≦ Y ≦ 5.0 and 3.5 ≦ Z ≦ 4.5.

According to the present invention, in the A _X Bi _Y Ti _Z O _{15 + M} structure, A is substituted with at least one element selected from the group consisting of Ca, Sr, Ba, La and Pb,
And X, Y and Z are each 0.5 ≦ X ≦ 1.
5, Dielectric porcelain composition having a high dielectric constant, a large no-load Q, and a small temperature change in resonance frequency in the range of 3.0 ≦ Y ≦ 5.0 and 3.5 ≦ Z ≦ 4.5. The thing is obtained. In particular, X = 1, Y = 4, Z = 4, that is, ABi ₄ Ti ₄ O
A dielectric porcelain composition having good properties in ₁₅ structures is obtained.

When X, Y and Z deviate from the above ranges, it is easy to form a hetero phase other than the basic structure of ABi ₄ Ti ₄ O ₁₅ and any one of the dielectric constant, the no-load Q and the temperature coefficient of the resonance frequency, or Two or more characteristics are degraded, and
Bi, Pb and the like are easily separated during firing, the amount of separation is not stable, and variations in electrical characteristics are likely to occur, so that X, Y, and Z are set in the above ranges. In the formula, M is a value obtained from the values of X, Y and Z.

The dielectric porcelain composition of the present invention is prepared by mixing starting materials such as calcium, strontium, barium, lanthanum, lead, bismuth and titanium oxides, carbonates, etc. After calcining,
It can be manufactured by a method of molding, firing and sintering. An example of a suitable method for producing the dielectric ceramic composition of the present invention will be described below.

First, calcium carbonate and strontium carbonate
, Barium carbonate, one of lanthanum oxide and lead oxide,
Or two or more and bismuth oxide and titanium oxide
Wet-mix with a predetermined amount of water or a solvent such as alcohol.
To meet. Then, after removing water or alcohol,
Grind and place in an oxygen-containing gas atmosphere (eg air atmosphere)
Calcination is performed at 900 to 1100 ° C. for about 1 to 5 hours. This
The calcined product obtained in this way was pulverized by a wet or dry method.
Then mix with an organic binder such as polyvinyl alcohol.
Combined and homogenized, dried and pressure-molded (pressure 100-15
00 kg / cm ²About). Uniaxial as a molding method
In addition to pressure molding, HIP, doctor molding, cast molding, etc.
But it's okay. The obtained molded product is placed in an oxygen-containing gas atmosphere such as air.
By firing at 1100 to 1300 ° C under ambient atmosphere
A dielectric ceramic composition represented by the above composition formula is obtained.

The dielectric ceramic composition thus obtained is processed as it is or into an appropriate shape and size as required, to thereby obtain a dielectric resonator and a microwave IC.
It can be used as a material for substrates, dielectric adjusting rods, etc.
An excellent effect is exhibited when used in the Hz to GHz band.

[0011]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples below.
A more specific description will be given. Example 1 Calcium carbonate (CaCO₃) Powder 14.29
Mol, bismuth oxide (Bi₂O ₃) 28.57 mol powder
And titanium oxide (TiO₂ ) Add 57.14 moles of powder to
Wet mix with ethanol in a mill for 12 hours. Melting
Evaporate the ethanol of the medium and crush it for 1 hour with a raider machine.
It was The pulverized product is calcined at 1000 ° C in an air atmosphere,
It was crushed again for 1 hour with a raider. A proper amount of this crushed material
After adding polyvinyl alcohol solution and drying, diameter 9mm
Form into pellets with φ and thickness of 4 mmt, and place in air atmosphere
Set at 1175 ° C for 2 hours and sinter and dielectric porcelain set
Product CaBi _FourTi_FourO₁₅Got Porcelain thus obtained
Pellets having a diameter of about 7 mm and a thickness of about 2 mmt
After processing into the
No load Q and relative permittivity ε at several (3 to 5 GHz)
_rI asked. Regarding the temperature dependence of the resonance frequency
Is the temperature coefficient τ measured in the range of 0 ° C to 50 ° C._fSeeking
It was The results are shown in Table 1.

Examples 2 to 25 Calcium carbonate (CaCO ₃ ) powder, strontium carbonate (SrCO ₃ ) powder, barium carbonate (BaCO ₃ ) powder, lanthanum oxide (La ₂ O ₃ ) powder, lead oxide (Pb)
O) powder, bismuth oxide (Bi ₂ O ₃ ) powder and titanium oxide (TiO ₂ ) powder, and the firing temperature was changed from 1125 ° C. to 1250 ° C. A porcelain composition was produced and its properties were evaluated.
The results are shown in Table 1.

Comparative Example 1 Calcium carbonate (CaCO ₃ ) powder, strontium carbonate (SrCO ₃ ) powder, bismuth oxide (Bi ₂ O ₃ ) powder and titanium oxide (TiO ₂ ) powder have the molar ratios shown in Table 1. The dielectric ceramic composition was manufactured in the same manner as in Example 1 except that the firing temperature was changed to 1225 ° C., and the characteristics were evaluated. The results are shown in Table 1.

Comparative Examples 2 to 4 Calcium carbonate (CaCO ₃ ) powder, strontium carbonate (SrCO ₃ ) powder, barium carbonate (BaCO ₃ ) powder, lanthanum oxide (La ₂ O ₃ ) powder, lead oxide (Pb)
O) powder, bismuth oxide (Bi ₂ O ₃ ) powder and titanium oxide (TiO ₂ ) powder, and the firing temperature was changed from 1125 ° C. to 1250 ° C. A porcelain composition was produced and its properties were evaluated.
The results are shown in Table 1.

[0015]

[Table 1]

[0016]

INDUSTRIAL APPLICABILITY The dielectric ceramic composition of the present invention has a particularly high dielectric constant, a large unloaded Q, a small change in resonance frequency with temperature, and is used in dielectric resonator materials, particularly in the MHz to GHz band. It is suitable as a resonator material. In addition to the dielectric resonator material, the dielectric ceramic composition of the present invention is also used in, for example, a dielectric substrate for microwave IC and a dielectric adjusting rod.

Claims (1)

[Claims] 1. A composition formula, A _X Bi _Y Ti _Z O _{15 + M} (wherein A represents at least one selected from the group consisting of Ca, Sr, Ba, La and Pb). It is a dielectric ceramic composition, and X, Y and Z are 0.5 ≦ X ≦ 1.5, 3.0 ≦ Y ≦ 5.0 and 3.5, respectively.
A dielectric ceramic composition in the range of ≤Z≤4.5.