JP3278520B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic used in a microwave region.

[0002]

2. Description of the Related Art In recent years, with the development of communication using electromagnetic waves in the microwave range, such as automobile telephones, portable telephones, and satellite broadcasting, downsizing of devices has been required.
For this purpose, it is necessary to reduce the size of individual components constituting the device. In these devices, a dielectric is incorporated in a filter element or an oscillation element as a dielectric resonator. When using the same resonance mode, the size of the dielectric resonator is inversely proportional to the square root of the relative permittivity (ε _r ) of the dielectric material. A material having a dielectric constant is required. In addition, for practical use as a dielectric resonator, it is necessary that the loss be low in the microwave region, that is, that the Q value be high and that the temperature coefficient (τ _f ) of the resonance frequency be small.

Conventionally, as a microwave dielectric for a dielectric resonator, Ba (Zn _1/3 Ta _2/3 ) O ₃ (Japanese Patent Publication No. 59-48484) has been used.
As described in Japanese Unexamined Patent Application Publication No. 2000-163, many perovskite ceramic compositions containing Ba at the A site have been developed. These dielectrics have very high Q values.

[0004]

However, the above-mentioned conventional dielectric porcelain composition has a low relative dielectric constant of about 30 and has a practical problem. Therefore, to reduce the size of the dielectric resonator,
Development of a microwave dielectric having a higher relative permittivity has been desired.

An object of the present invention is to provide a dielectric porcelain composition which solves the above-mentioned problems.

[0006]

In order to achieve this object, the present invention provides calcium oxide, nickel oxide, iron oxide,
When a composition comprising niobium oxide and titanium oxide is represented by a composition formula, Ca ｛(Ca _1/3 Nb _2/3 ) _1-x Ti _x ｝ O ₃ , x is 0.2 or more and 0.46 or less; Alternatively, when expressed as _{Ca {(Ni 1/3 Nb 2/3)} 1-x Ti x} O 3, x is 0.2 or more 0.53 or less, _{or, Ca {(Fe 1/2 Nb 1} / ₂ ) When expressed as _1-x Ti _x ｝ O ₃ , the dielectric ceramic composition is such that x is 0.2 or more and 0.52 or less.

[0007]

According to the dielectric ceramic composition of the present invention of the action The configuration, by selecting the Ti amount x of B site appropriately, since the dielectric constant is Ru can achieve tau _f = 0 in 35 above, the conventional In addition, the size of a dielectric resonator using a dielectric having a relative dielectric constant of about 30 can be reduced.

[0008]

An embodiment of the present invention will be described below.
The starting material is chemically pure CaCO_Three , Ni
O, Fe_Two O_Three , Nb_TwoO_Five , And TiO_Two Using
Was. After correcting the purity of the raw materials, the composition was changed to Ca ｛(C
a_1/3 Nb_2/3 )_1-x Ti_x ｝ O_Three , Ca ｛(Ni_1/3 
Nb_2/3 )_1-x Ti _x ｝ O_Three Or Ca あ る い は (Fe
_1/2 Nb_1/2 )_1-x Ti_x ｝ O_Three X when expressed as
The sample was weighed so as to have various values shown in FIG.

These powders were placed in a polyethylene ball mill, and a stabilized zirconia ball having a diameter of 5 mm and pure water were added thereto and mixed for 17 hours. After mixing, the slurry was dried, placed in an alumina crucible, and calcined at 900 to 1100 ° C. for 2 hours. After crushing the calcined body with a raikai machine,
It was pulverized for 17 hours by the above-mentioned ball mill and dried to obtain a raw material powder. 6% by weight of a 5% aqueous solution of polyvinyl alcohol was added as a binder to the powder, mixed, and then granulated through a 32 mesh sieve.
It was press-formed into a cylindrical shape having a thickness of about 6 mm and a thickness of about 6 mm. After heating the molded body at 600 ° C. for 2 hours to incinerate the binder, the molded body was placed in a magnesia-made porcelain container, and the lid was covered.
Calcination was carried out at various temperatures of 0 ° C. for 2 hours. Microwave dielectric properties of the sintered body fired at the temperature at which the density was highest were measured. The resonance frequency and the Q value were obtained by a dielectric resonator method. The dielectric constant was calculated from the dimensions of the sintered body and the resonance frequency. The resonance frequency was 2 to 5 GHz. Further, the resonance frequencies at −25 ° C., 20 ° C., and 85 ° C. were measured, and the temperature coefficient (τ _f ) was calculated by the least square method. Table 1 shows the results. Me and Ca in Table 1
i and Fe have the composition of Ca ｛(Ca _1/3 Nb _2/3 ), respectively.
_1-x Ti _x ｝ O ₃ , Ca ｛(Ni _1/3 Nb _2/3 ) _1-x T
i _x {O ₃ , Ca} (Fe _1/2 Nb _1/2 ) _1-x Ti _x }
It represents O ₃ .

[0010]

[Table 1]

As shown in Table 1, Ca 表 (Ca _1/3 N
b _2/3 ) _1-x Ti _x ｝ O ₃ system, Ca ｛(Ni _1/3 Nb _2/3 )
_1-x Ti _x ｝ O ₃ system, Ca ｛(Fe _1/2 Nb _1/2 ) _1-x T
In any of the systems i _x ｝ O ₃ , at a certain value of x, τ _f
= 0 can be realized. At that time, the relative dielectric constant of each of the composition systems was higher than 40, and the Qf product was 5000 GH.
It is expected that there will be more than z. On the other hand, when the value of x exceeds a certain range , the relative dielectric constant becomes about 30 which is conventionally used.
Whether a low, or tau _f becomes larger than 50 ppm / ° C., since further Qf product also becomes lower, avoids these
A possible x range greater than 0 was employed.

It should be noted that elements other than the claims, especially Ba,
Sr, Mn, Zn, Cr, Co, Cu, Si, Al, B
The content of an oxide composed of i, Pb, Ge, Sb, Ta, a rare earth element and the like may be within a range that does not adversely affect the dielectric properties.

[0013]

As is clear from the above description of the examples, according to the dielectric ceramic composition of the present invention, the relative dielectric constant is 3
When the value is as high as 5 or more, a high Q value and a small τf can be realized, so that the size of the dielectric resonator can be reduced. like this
The dielectric ceramic composition of the present invention includes not only a dielectric resonator, a circuit board for microwave, also available, such as the ceramic multilayer capacitor, denotes larger industrial value.

Continuation of the front page (56) References JP-A-5-24913 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3/12 335 C04B 35/46

Claims (3)

(57) [Claims] When a composition comprising calcium oxide, niobium oxide and titanium oxide is represented by a composition formula, Ca ｛(Ca _1/3 Nb _2/3 ) _1-x Ti _x ｝ O ₃ , x is 0. A dielectric porcelain composition characterized by being not less than 2 and not more than 0.46. 2. A composition comprising calcium oxide, nickel oxide, niobium oxide and titanium oxide, represented by a composition formula, Ca ｛(Ni _1/3 Nb _2/3 ) _1-x Ti _x ｝ O ₃ , x is 0.2 or more and 0.53 or less, The dielectric ceramic composition characterized by the above-mentioned. 3. A composition comprising calcium oxide, iron oxide, niobium oxide and titanium oxide, represented by a composition formula, Ca ｛(Fe _1/2 Nb _1/2 ) _1-x Ti _x ｝ O ₃ , x is 0.2 or more and 0.52 or less, The dielectric ceramic composition characterized by the above-mentioned.