JPH10101424A - Piezoelectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition capable of improving both the value of Q and the porcelain density (bulk density). SOLUTION: This piezoelectric porcelain composition comprises a principal component in which (x), (y) and (z) satisfy 0.40<=(x)<=0.55; 0.15<=(y)<=0.30; 0.20<=(z)<=0.30 and [(x)+(y)+(z)]=1 when the compositional formula expressed in terms of molar ratio is represented by xCaO.yMgO.zWO3 and at least one selected from (1) a boric acid compound in an amount of 0.01-0.2 pt.wt., expressed in terms of B2 O3 , (2) a phosphorus compound in an amount of 0.005-1 pt.wt., expressed in terms of P, (3) a silicon compound in an amount of 0.01-1 pt.wt. expressed in terms of SiO2 and (4) an alkali metal-containing compound in an amount of >=0.01 and <1 pt.wt., expressed in terms of a carbonate and respectively based on 100 pts.wt. principal component.

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 having a high relative dielectric constant and a high Q value in a high frequency region such as a microwave and a millimeter wave, and more particularly to a high frequency dielectric such as a dielectric resonator, a filter and a capacitor. The present invention relates to a dielectric porcelain composition suitable for electronic parts for use, MIC dielectric substrates, millimeter wave waveguides, and the like.

[0002]

2. Description of the Related Art In the high frequency region such as microwaves and millimeter waves, dielectric ceramics are widely used for dielectric resonators, MIC dielectric substrates, and the like. Recently, dielectric waveguides have been applied to millimeter wave waveguides.

[0003] Conventionally, as this kind of dielectric porcelain,
For example, ZrO ₂ —SnO ₂ —TiO ₂ based material, BaO—
TiO ₂ -based materials, (Ba, Sr) (Zr, Ti) O ₃ -based materials and Ba (Zn, Ta) O ₃ -based materials are known, and these materials have a frequency of 500 MHz through various improvements.
A dielectric constant of 20 to 40 and a Q value of 100 at z to 5 GHz.
0 to 3000 (Qf = 15000 or less), and the temperature coefficient (τf) of the resonance frequency is close to 0 ppm / ° C.

[0004]

However, recently, there has been a tendency to use higher frequencies,
Dielectric materials are required to have better dielectric properties, especially improved Q values. However, at present, the above-mentioned conventional dielectric material does not have a practically high Q value in a used frequency range of 10 GHz.

[0005]

The present inventors have conducted various studies on the above problems and found that xCaO.yMgO
Against · Zwo represented by the composition _3, boron (B),
It has been found that by including a predetermined amount of at least one of phosphorus (P), silicon (Si), and an alkali metal element, the Q value can be improved and the porcelain density (bulk density) can be improved. Reached.

That is, the main component of the dielectric porcelain composition of the present invention contains Ca, Mg and W as metal elements, and the composition formula based on the molar ratio of these metal element oxides is xCaO.yMgO.zWO ₃ . When expressed, the x, y and z satisfy 0.40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 x + y + z = 1. The dielectric porcelain composition of the present invention contains the boric acid compound in an amount of 0.01 to 0.2 in terms of B ₂ O ₃ with respect to the main component and 100 parts by weight of the main component.
Parts, 0.005 parts by weight of phosphorus compound P terms, a silicon compound 0.01 to 1 part by weight in terms of SiO _2, the alkali metal-containing compound with carbonate terms 0.01
Not less than 1 part by weight and at least one selected from the above.

[0007]

According to the dielectric ceramic composition of the present invention, xCaO.y
The Q value is improved by adding a predetermined amount of at least one of boron (B), phosphorus (P), silicon (Si), and an alkali metal element to the composition represented by MgO · zWO _3. Thus, the porcelain density (bulk density) can be improved.
And, by having a high porcelain density (bulk density), high strength can be realized.

That is, by adding a predetermined amount of a boric acid compound, a phosphorus compound, a silicon compound, and an alkali metal-containing compound to the main component, sintering is promoted, and a high porcelain strength and a high Q value can be obtained. .

[0009]

The dielectric ceramic composition of the present invention DETAILED DESCRIPTION OF THE INVENTION, when expressed the composition formula by molar ratio xCaO · yMgO · zWO _3, wherein x, y, z is 0.40 ≦ x ≦ 0.55 ,
0.15 ≦ y ≦ 0.30, 0.20 ≦ z ≦ 0.30, x
Although the composition satisfying + y + z = 1 is the main component, the reason why the composition ratio is limited to the above-mentioned range is that if it is outside the above-mentioned range, problems such as a decrease in sinterability and a decrease in the Q value occur. .

That is, the reason why the molar ratio x of CaO is set to 0.40 ≦ x ≦ 0.55 in the above composition formula is that x is 0.40 ≦ x ≦ 0.50.
This is because the Q value is reduced when the value is smaller than 0.5 or larger than 0.55. It is preferable that x satisfies 0.48 ≦ x ≦ 0.52 from the viewpoint of improving the Q value.

Further, the molar ratio y of MgO is 0.15 ≦ y ≦
The reason for setting the value to 0.30 is that when y is smaller than 0.15, the Q value decreases, and when y is larger than 0.30, the Q value decreases or sintering becomes poor. It is desirable that y satisfies 0.22 ≦ y ≦ 0.28 from the viewpoint of improving the Q value and sinterability.

Further, the molar ratio of WO ₃ is set to 0.20 ≦ z ≦
The reason for setting it to 0.30 is that the Q value decreases when z is smaller than 0.20 or larger than 0.30. z is 0.22 ≦ y ≦ 0 because of improvement of Q value.
28 is desirable.

The main component of the dielectric porcelain composition of the present invention is a composition formula based on the molar ratio of a metal element oxide, xCaO.yMg.
When expressed as _{O · zWO 3, x, y} , z is 0.48 ≦ x ≦
0.52, 0.22 ≦ y ≦ 0.28, 0.22 ≦ z ≦
It is desirable that 0.28 and x + y + z = 1 be simultaneously satisfied.

The dielectric porcelain composition of the present invention contains 10 main components.
(1) 0.01 to 0.20 parts by weight of a boric acid compound in terms of B ₂ O ₃ , (2) 0.005 to 1 parts by weight of a phosphorus compound in terms of P, and (3) silicon Compound SiO
0.01 to 1 part by weight in terms of ₂ ; (4) an alkali metal-containing compound in an amount of 0.01 to less than 1 part by weight in terms of carbonate; and at least one selected from the above (1) to (4). Things.

The reason that the content of the boric acid compound is 0.01 to 0.20 parts by weight in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component is that the porcelain density (volume) is less than 0.01 part by weight. This is because there is almost no effect on the improvement of the density) and the Q value, and when it exceeds 0.20 parts by weight, the Q value decreases. The content of the boric acid compound has a high ceramic density is 0.025 to 0.2 parts by weight from the viewpoint of obtaining a high Q value in terms _of B ₂ O ₃ is desirable.

The content of the phosphorus compound is set to 0.005 to 1 part by weight in terms of P with respect to 100 parts by weight of the main component.
This is because there is almost no effect on the improvement of Q and the Q value, and when it exceeds 1 part by weight, the Q value decreases. The content of the phosphorus compound can be increased from the point that a higher porcelain density and a higher Q value are obtained.
Desirably, it is 0.025 to 1 part by weight in conversion.

Furthermore, the reason why the silicon compound is used in an amount of 0.01 to 1 part by weight in terms of SiO ₂ with respect to 100 parts by weight of the main component is that when less than 0.01 part by weight, the porcelain density (bulk density) is improved. This is because there is almost no effect on the improvement of the Q value, and when it exceeds 1 part by weight, the Q value decreases. The silicon compound is desirably 0.1 to 1 part by weight in terms of SiO ₂ from the viewpoint of obtaining a higher porcelain density and a higher Q value.

Further, an alkali metal-containing compound is used in an amount of 0.01 part by weight or more in terms of carbonate with respect to 100 parts by weight of the main component.
The reason that the amount is less than 0.01 part by weight is that there is little effect on the improvement of the porcelain density (bulk density) and the Q value when the amount is less than 0.01 part by weight, and the Q value decreases when the amount is 1 part by weight or more. is there.
The alkali metal-containing compound is desirably 0.1 to 0.9 parts by weight in terms of carbonate in terms of obtaining a high porcelain density and a high Q value.

Here, B ₂ O ₃ ,
There are colemanite, CaB ₂ O ₄ , ZnB ₂ O _{4 and the} like.
Examples of the phosphorus compound include H ₃ PO ₄ , P ₂ O ₅ , and P. As the alkali metal, Li, Na, K,
Rb and Cs.

As a method for producing a porcelain according to the present invention, for example, oxides of Ca, Mg, W or metal salts such as carbonates and nitrates which form oxides upon firing are prepared as main raw materials, and these are fired. After being weighed so that the aggregate is in the above-mentioned range, it is mixed well. Then, the mixture is 900
Calcination is performed at ~ 1200 ° C. For example, a boric acid compound such as B ₂ O ₃ , a phosphorus compound such as P ₂ O ₅ , a silicon compound such as SiO ₂ , Li ₂ CO 3
Each of the alkali metal-containing compounds such as ₃ is weighed to a predetermined amount, added, and mixed and pulverized. Then, this is molded into a predetermined shape by a molding method such as press molding or a doctor blade method. Next, the molded body is fired at 1300 ° C. to 1600 ° C. in an oxidizing atmosphere such as the air to obtain a dielectric ceramic.

In the dielectric ceramic composition of the present invention, Cl, Al, P, Na, Sr, Zr, Y, and the like may be mixed as unavoidable impurities. There is no problem in characteristics. In addition, metal or the like may be mixed in the crushed balls during crushing.

In the dielectric ceramic composition of the present invention, a perovskite-type crystal phase represented by Ca (Mg _1/2 W _1/2 ) O ₃ is used as a main crystal phase. That is, it has a crystal in which the A site is composed of Ca and the B site is composed of Mg and W at a ratio of 1: 1. The material having such a crystal may be in any form of a polycrystal such as a sintered body or a single crystal. In the dielectric porcelain composition of the present invention, CaWO ₄ , CaW ₂ O ₉ , and Ca ₂ WO are used as crystal phases other than Ca (Mg _1/2 W _1/2 ) O _3.
5 may be present, but there is no problem in characteristics if the amount is small.

[0023]

【Example】

Example 1 Using powders of CaCO ₃ , MgCO ₃ and WO _{3 having} a purity of 99% or more as raw materials, weighing them in the proportions shown in Table 1 and putting them in a ball mill lined with rubber together with IPA for 18 hours Mixed. Next, after drying this mixture, it was calcined at 1000 ° C. for 2 hours. B ₂ O ₃ in the calcined _{product, H 3 PO 4, SiO 2} , Li 2 CO 3, N
a ₂ CO ₃ and K ₂ CO ₃ were weighed so as to have the ratios shown in Table 1, and the calcined product was put into a ball mill using ZrO ₂ balls together with IPA and wet-pulverized for 18 hours.

[0024] Thereafter, the pulverized product was dried, after addition of organic binder, 40th granulated through mesh of the mesh, the size of the resulting powder 3000 kg / pressure cm ² diameter 10 mm × thickness 5mm cylinder Molded. Furthermore,
This cylinder was fired at 1500 ° C. for 6 hours to obtain a ceramic sample having a diameter of 8.5 mm and a thickness of 4.3 mm.

The bulk density of the porcelain sample thus obtained was measured in accordance with JIS C2141-1992 (Testing method for ceramic materials for electrical insulation). The relative permittivity (εr) and Q value at a frequency of about 11 GHz were measured by the dielectric resonator method, and the Q value was converted to a Q value at 10 GHz on the assumption that the general formula Qf = constant. TE at each temperature from 25 ° C to 85 ° C
The temperature coefficient (τf) of the 011 mode resonance frequency is represented by τf =
[(F ₈₅ −f ₂₅ ) / f ₂₅ ] / 60 × 10 ⁶ [ppm /
° C]. Here, f ₈₅ is the resonance frequency at 85 ° C., and f ₂₅ is the resonance frequency at 25 ° C. The results are shown in Table 1.

[0026]

[Table 1]

According to Table 1, CaO, MgO, WO
No. ₃ whose composition is outside the scope of the present invention. 1-3, 11,
In Nos. 15 to 17, the Q value was 1000 or less or sintering failure occurred. On the other hand, No. 1 according to the present invention. 4 to 10 and 12 to 14 obtained high Q values of 4000 or more. Also, in Comparative Example No. It is expected that a porcelain having a higher density than that of No. 18 will be obtained and the strength will be increased.

Example 2 Sample No. 1 in Table 1 in Example 1 was used. B, P, Si and an alkali metal element were added in the amounts shown in Table 2 to the main components of No. 8 and molded and fired in the same manner as in Example 1.

Then, in the same manner as in Example 1, the bulk density, the relative dielectric constant, the Q value, and the temperature coefficient (τf) of the resonance frequency were determined. Table 2 shows the results.

[0030]

[Table 2]

According to Table 2, the boric acid compound was converted to 0.01 to 0.20 in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component.
Parts by weight, 0.005 to 1 part by weight of a phosphorus compound in terms of P,
By adding a silicon compound in an amount of 0.01 to 1 part by weight in terms of SiO ₂ and an alkali metal-containing compound in an amount of 0.01 to less than 1 part by weight in terms of carbonate, the bulk is larger than that of Sample No. 18 in which these are not added. It can be seen that the density increases and the Q value also increases. In addition, the kind of additive of Table 1 and Table 2 described the converted compound or metal.

[0032]

As described in detail above, boron, phosphorus, silicon, and the main component consisting of CaO, MgO and WO ₃
By containing the alkali metal element in a predetermined amount, the bulk density can be improved, the strength can be increased, and the Q value can be increased. The resulting porcelain is a resonator material used in the microwave and millimeter wave regions, M
It can be sufficiently applied to a dielectric substrate material for IC, a material for a capacitor, a material for a dielectric antenna, a material for a dielectric waveguide, and the like.

Claims (4)

[Claims] [Claim 1] containing Ca, Mg and W as the metal element, when expressed as xCaO · yMgO · zWO ₃ the composition formula by molar ratio of the metal element oxides, wherein x, y and z are 0. With respect to a main component satisfying 40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 x + y + z = 1 and 100 parts by weight of the main component,
The dielectric ceramic composition characterized in that it contains 0.01 to 0.2 parts by weight of boric acid compound terms _of B ₂ O _3. 2. A contains Ca, Mg and W as the metal element, when expressed as xCaO · yMgO · zWO ₃ the composition formula by molar ratio of the metal element oxides, wherein x, y and z are 0. With respect to a main component satisfying 40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 x + y + z = 1 and 100 parts by weight of the main component,
A dielectric ceramic composition comprising a phosphorus compound in an amount of 0.005 to 1 part by weight in terms of P. 3. Ca as the metal element, and contains Mg and W, when the composition formula by molar ratio of the metal element oxide was expressed as xCaO · yMgO · zWO _3, wherein x, y and z are 0. With respect to a main component satisfying 40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 x + y + z = 1 and 100 parts by weight of the main component,
The dielectric ceramic composition characterized in that it contains 0.01 to 1 parts by weight of silicon compound in terms of SiO _2. 4. contain Ca, Mg and W as the metal element, when the composition formula by molar ratio of the metal element oxide was expressed as xCaO · yMgO · zWO _3, wherein x, y and z are 0. With respect to a main component satisfying 40 ≦ x ≦ 0.55 0.15 ≦ y ≦ 0.30 0.20 ≦ z ≦ 0.30 x + y + z = 1 and 100 parts by weight of the main component,
A dielectric ceramic composition comprising an alkali metal-containing compound in an amount of 0.01 to less than 1 part by weight in terms of carbonate.