JPH07262825A - Dielectric porcelain composite - Google Patents

Abstract

PURPOSE:To provide a dielectric porcelain composite which has a high dielectric constant, a large Q value, and a good stability of tauf. CONSTITUTION:This dielectric porcelain composite is composed by adding at least one sort of MnO, WO3, NiO, and ZnO less than 2wt.%, as an auxiliary component, to the main component which consists of Ca, Mg, Ti, Nd, and O, shown in the composition formula: x [(CaO)1-L(MgO)L].yTiO2.zNd2O3. In the formula, 0.4<=x<=0.72, 0.25<=y<=0.485, 0.03<=z<=0.20, 0<L<1, x+y+z=1, and x/y>1.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a main component composed of calcium, magnesium, titanium, neodymium and oxygen, which is suitable as a dielectric resonator material, and Mn as a subcomponent.
The present invention relates to a dielectric ceramic composition containing 2% by weight or less of at least one of O, WO ₃ , NiO and ZnO. 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 , stability of the temperature coefficient τ _f of the resonance frequency, and linearity of the temperature characteristic of the resonance frequency. Characteristics such as excellent and large no-load Q are required.

As such a dielectric ceramic composition,
It is known that TiO ₂ , BaO—TiO ₂ or the like is the main component, but it is difficult to put into practical use because of its large temperature coefficient and large dielectric loss in the microwave band. In addition, (1-x) La (Mg _1/2 Ti _1/2 ) O
There is also a proposal for a dielectric ceramic composition of _3- xCaTiO ₃ (Japanese Patent Laid-Open No. 61-128411), but a sufficiently large Q value has not been obtained.

Further, Ba (Mg _1/3 Ta _2/3 ) O ₃ system, B
a (Zn _1/3 Ta _2/3 ) O ₃ system, Ba (Zn _1/3 Nb _2/3 ).
Dielectric porcelain compositions having a perovskite type structure such as O ₃ system are also known, but these have a drawback that the resonator becomes too large, for example, in the 0.1 to 5 GHz band because of their small relative permittivity. .

[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 ε _r .

[0006]

The inventors of the present invention have found that a dielectric
Among the many constituent elements used in porcelain compositions,
Lucium, magnesium, titanium, neodymium and oxygen
To a specific porcelain composition consisting of a combination of
nO, WO₃, NiO and ZnO at least 1
It was found that the above objectives can be achieved by adding seeds.
It was The present invention provides a composition formula, x [(CaO)_1-L(MgO)
_L] ・ YTiO₂・ ZNd ₂O₃(In the formula, 0.4 ≦ x ≦
0.72, 0.25 ≦ y ≦ 0.485, 0.03 ≦ z ≦
0.20, 0 <L <1, x + y + z = 1, x / y> 1
is there. ), Calcium, magnesium, tita
In addition to the main component consisting of nitrogen, neodymium, and oxygen, a sub-component
As MnO, WO₃, NiO and ZnO
Dielectric porcelain composition containing at least 2% by weight of at least one kind
It is about things.

The dielectric ceramic composition of the present invention has a relative dielectric constant of
Since it is large, the resonator can be downsized and the unloaded Q is also large.
Become Furthermore, the temperature coefficient τ of the resonance frequency_fIs small. Book
In the present invention, the addition of the mole fractions of CaO and MgO
Over 0.72 or TiO ₂Has a molar fraction of 0.25
If it is smaller, the dielectric constant becomes smaller. Also CaO and MgO
The sum of the mole fractions of₂Equal to or less than the mole fraction of
Temperature coefficient τ of resonance frequency_fBecomes larger,
The sum of the mole fractions of CaO and MgO and TiO₂Mole fraction of
Is limited to the above range. Furthermore, the molar fraction of MgO,
When the ratio of the sum of the mole fractions of CaO and MgO is 0, τ_f
Rises, and a dielectric constant of 1 decreases, so MgO
The ratio between the mole fraction and the sum of the mole fractions of CaO and MgO is
Limited to the above range. Nd₂O₃Has a mole fraction of 0.03
If smaller, τ_fIs larger than 0.20
As the no-load Q becomes smaller, Nd₂O₃of
The mole fraction is limited to the above range. In addition, MnO, WO
₃, NiO and ZnO were all added in an amount of 0% by weight.
Or, if the addition amount of one kind is more than 2% by weight, no load Q
Therefore, the addition amount of subcomponents is not limited to the above range.
Be done.

An example of a suitable method for producing the dielectric ceramic composition of the present invention will be described below. Starting materials of calcium carbonate, magnesium oxide, titanium oxide, and neodymium oxide are wet-mixed in predetermined amounts with a solvent such as water or alcohol. Then, after removing water, alcohol, etc., the powder is pulverized and then dried in an oxygen-containing gas atmosphere (for example, an air atmosphere) at 1000 to 130.
Calcination is performed at 0 ° C. for about 2 to 25 hours. The calcined product thus formed is crushed into MnO, WO ₃ , NiO, Zn
After adding at least one kind of O in a predetermined amount, it is mixed with an organic binder such as polyvinyl alcohol to be homogenized, dried, pulverized, and pressure-molded (pressure 100 to 1000).
Kg / cm ² ). Then, the molded product is fired at 1350 to 1650 ° C. in an oxygen-containing gas atmosphere such as air to obtain the dielectric ceramic composition represented by the above composition formula.

The dielectric ceramic composition thus obtained is processed as it is, or if necessary, processed into an appropriate shape and size to obtain a dielectric resonator, a dielectric substrate for microwave IC, a dielectric adjusting rod. Etc., and particularly when used as a dielectric resonator used in the 0.1 to 5 GHz band, excellent effects are exhibited.

The raw materials for calcium, magnesium, titanium and neodymium include CaCO ₃ , MgO and T.
In addition to iO ₂ , Nd ₂ O _{3 and the} like, carbonates, hydroxides and the like which become oxides during firing can be used.

[0011]

EXAMPLES The present invention will be described more concretely with reference to the following examples. Example 1 Calcium carbonate (CaCO ₃ ) powder, magnesium oxide (MgO) powder, titanium oxide (TiO ₂ ) powder, and neodymium oxide (Nd ₂ O ₃ ) powder were put in a ball mill together with ethanol and wet-mixed for 12 hours. This mixture was taken out of the ball mill, the solvent ethanol was evaporated, the mixture was crushed for 1 hour by a muller, and calcined in an air atmosphere at 1000 ° C. for 5 hours to obtain 0.6 [CaO _0.92 MgO _0.08 ].
A calcined powder of 0.3TiO ₂ .0.1Nd ₂ O ₃ was obtained.

Next, 0.05% by weight of MnO was added to the calcined powder, and an appropriate amount of polyvinyl alcohol solution was added and uniformly mixed.
Molded into pellets with a thickness of 5 mm and placed in an air atmosphere for 150
The dielectric ceramic composition of the present invention was obtained by firing and sintering at 0 ° C. for 2 hours. The porcelain composition thus obtained was cut into an appropriate size and then measured by a dielectric resonance method to obtain an unloaded Q and a relative permittivity ε _r at a resonance frequency f ₀ (3 to 6 GHz). The temperature dependence of the resonance frequency was measured in the range of -40 to 50 ° C to obtain the temperature coefficient τ _f . The results are shown in Table 2.

Examples 2 to 23 Mixing ratios of calcium carbonate, magnesium oxide, titanium oxide and neodymium oxide of Example 1, and MnO and W.
A dielectric ceramic composition was produced in the same manner as in Example 1 except that the amounts of O ₃ , NiO and ZnO added were changed as shown in Table 1, and the characteristics were measured in the same manner as in Example 1. The results are shown in Table 2.
Shown in. Those marked with * in the table are comparative examples outside the scope of the present invention.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

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, x [(CaO) _{1 -L} (Mg
O) _L ] · yTiO ₂ · zNd ₂ O ₃ (wherein 0.4 ≦
x ≦ 0.72, 0.25 ≦ y ≦ 0.485, 0.03 ≦
z ≦ 0.20, 0 <L <1, x + y + z = 1, x / y>
It is 1. ), Calcium, magnesium,
A dielectric ceramic composition comprising 2% by weight or less of at least one of MnO, WO ₃ , NiO and ZnO as a sub-component added to a main component composed of titanium, neodymium and oxygen.