JP3536861B2 - Dielectric porcelain material - 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 material mainly used for communication equipment for a microwave band.

[0002]

2. Description of the Related Art In recent years, with the advance of communication technology and the spread of mobile communication such as automobile telephones and mobile telephones, the band used for transmission and reception in communication equipment has extended to the microwave band. For this reason, electronic components such as semiconductor devices used for communication equipment are also being adapted for use in the microwave band.

[0003] In the past, cavity resonators, antennas, and the like have been used for such electronic components (circuits) for the microwave frequency band, but such electronic components are as large as the wavelength of the microwaves themselves. Therefore, miniaturization is
It was virtually impossible.

On the other hand, in a microwave filter using a recent dielectric resonator used in a microwave frequency band, a small dielectric resonator for stabilizing the frequency of a transmitter, and the like, a dielectric material is used. Attempts to reduce the size of the main body by using materials have been actively made. The downsizing of electronic components (circuits) is an indispensable requirement especially for popularizing mobile phones and the like, and is regarded as very important.

[0005] In order to reduce the size of such resonators and filters, the characteristics required of the dielectric material include a dielectric constant ε _r
Is large, and the dielectric loss (ta) in the microwave frequency band is large.
nδ = D = 1 / Q) is small, that is, the Q value (energy stored in the vibration circuit / energy consumed in one cycle) is high, and the temperature coefficient τ _f of the resonance frequency is as close to zero as possible. Is mentioned.

As dielectric ceramic materials satisfying these requirements, there are BaO-TiO ₂ based materials, materials in which a part thereof is replaced by other elements, and the like, and a temperature coefficient τ _{f of the} resonance frequency is negative. And the temperature coefficient is improved by combining a positive material and a positive material.

In recent years, when a rare earth oxide is added to a BaO—TiO ₂ dielectric ceramic material, the temperature coefficient of the resonance frequency becomes close to zero, and a large dielectric constant ε _r and a high Q value can be obtained. It has been known. Therefore, at present, BaO-TiO thus added with rare earth oxides
_Two- system dielectric porcelain materials are being widely used.

[0008]

As the conventional dielectric ceramic material for the microwave band, besides the above-mentioned materials, B
a (Zn _1/3 Ta _2/3 ) O ₃ type or BaO-T
iO ₂ system, or _ZrO 2 -SnO ₂ -TiO
Those of the _second type and the like are known.

However, any of these dielectric ceramic materials has an improved Q × f value and a temperature coefficient τ of the resonance frequency.
_{Although the f-} characteristic (close to zero) can be improved, the dielectric constant ε _r is suppressed to about 40, so that there is a problem that it is difficult to use as a small electronic component material in a low frequency band.

[0010] In view of the above, a system in which a rare earth oxide is added to the above-described BaO-TiO ₂ dielectric ceramic material, or a system in which PbO, Bi ₂ O ₃ or the like is further added, has a dielectric constant ε.
_r is known to be 80 to 100, but in such a system, the Q value in the microwave band is
-TiO ₂ system and _ZrO 2 -SnO ₂ -TiO ₂
There is a disadvantage that it is inferior to a system or the like.

Further, most of the dielectric ceramic materials of these composition systems are mixed crystal systems, and there are differences in the corrosion resistance of each phase from acid to acid in the crystal structure. If so, unevenness is likely to occur when etching is performed prior to electrode attachment. In such a case, unevenness occurs on the dielectric surface, and the Q value is reduced when the filter is manufactured.

By the way, L is added to the BaO-TiO ₂ compound.
An old report [Berichte der De] showed that the addition of a ₂ O ₃ could improve the dielectric properties.
utschen Keramischen Gesel
lschaft e. V. , 35 (1958), 6
9]. According to this report, the phase transition temperature decreases as the amount of La ₂ O ₃ .3TiO ₂ added to BaTiO ₃ increases, and eventually the ferroelectric phase disappears and the temperature coefficient of the dielectric constant ε _r . It has been shown that τε decreases.

However, BaO—La ₂ O ₃ —
The TiO ₂ -based compound has a dielectric property in a microwave band that cannot withstand practical use. For example, BaO-L
In the case of a dielectric ceramic having a composition of a ₂ O ₃ -4TiO ₂ , τ _f = 380 [ppm / ° C.] and Q × f = 16
00 [GHz], which does not satisfy the characteristics required for the dielectric filter material.

Accordingly, the BaO-La ₂ O ₃ -T
Attempts have been made to improve the dielectric properties by adding various additional elements to the iO ₂ system. For example, PbO
The compounds to which is added are described in JP-B-62-23404 and JP-A-1-317166. Also, Sn
Japanese Patent Publication No. 2-2822 is an example to which O ₂ is added.

However, these dielectric ceramic materials have a dielectric constant ε _r of 85 or more and an absolute value of the temperature coefficient τ _f of the resonance frequency of 180 [ppm / ° C.] or less in each case. No composition range that satisfies the condition has been found, and therefore there is a limit on the dielectric properties.

On the other hand, in the case of a BaO-TiO ₂ -rare earth oxide-based dielectric ceramic material, Nd ₂ O ₃ or Sm ₂ O _3, which is in high demand as a rare earth magnet material, is mainly used as a main component of the rare earth oxide. Therefore, although it is possible to obtain very excellent dielectric properties, it is still unfavorable from the viewpoint of using rare earth elements to obtain rare earth oxides.

Incidentally, of the lanthanoid elements having the atomic numbers 57 to 71, La is present in excess in the earth's crust because it has the second highest abundance after Ce and has almost no use. B which selected La as a rare earth element
The dielectric material _{aO-La 2} O 3 -TiO ₂ system, and _BaO-TiO 2 _-Nd 2 _{O 3} based BaO-
Although the dielectric constant is higher than that of the TiO ₂ —Sm ₂ O ₃ system or the like, the Q × f value and the temperature coefficient τ _f characteristic of the resonance frequency deteriorate as much as the dielectric ceramic material cannot be used. In particular, the characteristic deterioration of the temperature coefficient τ _f is remarkable, and also in this case, the dielectric constant ε _r is 85 or more and the absolute value of the temperature coefficient τ _f of the resonance frequency is 180 [ppm / ° C.] or less. No composition range that satisfies the condition is found.

In short, a conventional dielectric porcelain material having excellent dielectric characteristics, that is, a material having a large dielectric constant ε _r , exhibiting a high Q value, and having a small temperature coefficient τ _f of the resonance frequency is a resource-intensive material. And expensive Nd and Sm
BaO-TiO ₂ —Nd ₂ O ₃ using a large amount of
Not found in the other ones of the system and _BaO-TiO 2 _-Sm 2 _{O 3} system.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and its technical problem is that the dielectric characteristics are sufficiently balanced and excellent, and at the same time, an inexpensive microwave band compatible dielectric material which is not restricted by resources. It is to provide a body porcelain material.

[0020]

According to the present invention According to an aspect of the general formula _{(Ba 1-x, Pb x} ) O- (La 1-y, Gd y) 2
O ₃ —TiO ₂ [however, 0.25 <x ≦ 0.65,0.
25 ≦ y ≦ 0.65] and (B
_{a 1-x, Pb x)} O a 11.7 to 21.7 _{[mol%], (La 1-y} , the Gd _y) 2 _{O 3} 11.7~2
A dielectric ceramic material having a composition ratio of 1.7 [mol%] with TiO ₂ as the balance is obtained.

[0021]

According to the present invention, the general formula (Ba _1-x , Pb _x ) O
_{- (La 1-y, Gd} y) 2 O 3 -TiO 2 [ however,
0.25 <x ≦ 0.65, 0.25 ≦ y ≦ 0.65], and (Ba _1-x , Pb _x ) O is 11.7 to 21.7 [mol%], (La _1-y , G
The d _{y) 2} O ₃ 11.7~21.7 [mol%], TiO
_{In the} dielectric porcelain material obtained with a component composition ratio with the balance being ₂ , the (La _1-y , Gd _y ) ₂ O ₃ compound is used for La.
Is replaced by Gd, it is noted that even _if the characteristic of the temperature coefficient τ _f of the resonance frequency is improved, the dielectric constant ε _r is lowered, and the Q × f value is not improved.
_1-x , Pb _x ) O compounds are used to partially replace Ba with Pb. Such a dielectric ceramic material has a dielectric constant ε _r of 85 or more, an absolute value of a temperature coefficient τ _f of resonance frequency of 180 [ppm / ° C.] or less, and a Q × f value of 2000
Since the probability of exhibiting an excellent dielectric property of [GHz] or more is increased, the material is most suitable as a dielectric ceramic material for a microwave band.

[0022]

EXAMPLES The following is a detailed description of the dielectric ceramic material of the present invention with reference to examples. First, the outline of the dielectric ceramic material of the present invention will be briefly described.

This dielectric ceramic material has a general formula (Ba)
_{1-x, Pb x) O-} (La 1-y, Gd y) 2 O 3 -
TiO ₂ [However, 0.25 <x ≦ 0.65, 0.25 ≦
y ≦ 0.65] and (Ba
_1-x , Pb _x ) O is 11.7 to 21.7 [mol%],
_{(La 1-y, Gd y} ) a 2 _{O 3} 11.7 to 21.7
[Mol%], which can be obtained at a component composition ratio with TiO ₂ as the balance.

Therefore, the dielectric ceramic material will be described more specifically, including its manufacturing method. First, TiO ₂ , PbO, BaCO ₃ , La ₂ O as raw materials
₃ , Gd ₂ O ₃ were prepared, and these raw materials were weighed so as to have the required composition ratio (molar ratio) described above, and were wet-mixed with zirconia balls in a resin ball mill to obtain a mixture. Next, after drying this mixture, it was calcined in air at a temperature condition of 1050 [° C.] to obtain a calcined product. Further, the calcined product is wet-pulverized by the above-mentioned ball mill, and then formed into a disk having a diameter of 15 mm and a thickness of about 6 mm.
To obtain a dielectric ceramic material.

Table 1 shows that the resonance frequency of the dielectric porcelain was 2 for the dielectric porcelain separately manufactured using a total of 26 kinds of dielectric porcelain materials (samples) manufactured in this way and having different component composition ratios. The dielectric constant ε _r , Q × f value, and −25 to 3.5 [GHz] are obtained by the cavity resonator method.
It shows a measurement result regarding the temperature coefficient τ _f of the resonance frequency at 80 [° C.].

[0026]

[Table 1]

In Table 1, any of the dielectric porcelain materials
Its composition is a (Ba _1-x , Pb _x ) Ob (La
_1-y, represented by _{Gd y) 2 O 3 -cTiO 2} . Here, a, b, and c each represent a molar ratio (mol%), and have a relationship of a + b + c = 100.

From Table 1, it can be seen that No. _{2 in} which BaO was partially replaced by PbO and La ₂ O ₃ was partially replaced by Gd ₂ O ₃ . 9 to 26 (however, No. 9 to 26).
No. 1 to No. 12 dielectric ceramics; Dielectric ceramics having compositions of Nos. 15 and 18; The dielectric ceramic according to the composition of 20 to 26 and Comparative Example) are improved dielectric constant epsilon _r of most things, especially No. No. 9 to No. 19 dielectric ceramics and 21 and No. 21. A dielectric porcelain having a composition of 24 has a dielectric constant ε _r of 85 or more, an absolute value of a temperature coefficient τ _f of a resonance frequency of 180 [ppm / ° C.] or less,
It can be seen that the material exhibits excellent dielectric properties with a Q × f value of 2000 [GHz] or more. The dielectric porcelains having compositions of Nos. 19 dielectric ceramics.

On the other hand, as a comparative example which is out of the composition range of the present invention, No. The dielectric porcelain with the composition of 1 to 8 is
No. in which a part of BaO was replaced with PbO. 5 and No. 5 6
Of La ₂ O ₃ and Gd ₂
No. ₃ substituted with O ₃ 7 and No. 7 No. 8 shows comparatively excellent dielectric properties as compared with the composition of No. 8, but no substitution with Pb or Gd is performed. It can be seen that each of the compositions of Nos. 1 to 4 has a characteristic defect.

[0030]

As described above, according to the present invention, a dielectric material for a microwave band having an excellent balance of dielectric properties such that the dielectric constant and Q × f value are large and the temperature coefficient of the resonance frequency is small. A body porcelain material is obtained. This dielectric porcelain material uses Nd or Sm
Is obtained by substituting a part of La with Gd and substituting a part of Ba with Pb without using, so that it can be provided at a low cost, and in order to reduce the size of resonators and filters. Can greatly contribute,
It is very useful industrially.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01B 3/12 303 H01B 3/12 308 C04B 35/46 H01P 7/10

Claims (1)

(57) [Claims] 1. The formula (Ba _1-x , Pb _x ) O- (L
_{a 1-y, Gd y)} 2 O 3 -TiO 2 [ however, 0.25
<X ≦ 0.65, 0.25 ≦ y ≦ 0.65], and (Ba _1-x , Pb _x ) O is 11.7.
～21.7 _{[mol%], (La 1-y} , Gd y) 2 O 3
11.7 to 21.7 [mol%], and a composition ratio of TiO ₂ as a balance.