JPH06203631A - Dielectric porcelain composition - Google Patents

Abstract

(57) [Abstract] [Purpose] High permittivity and temperature coefficient of resonance frequency τ
Disclosed is a microwave dielectric material having a high dielectric constant, which is a dielectric material whose _f can be adjusted to around 0 ppm / ° C. and which has a practically unloaded Q value in the microwave region. [Composition] A dielectric ceramic composition comprising lead oxide, calcium oxide, zirconium oxide, and tin oxide, wherein the composition ratio of each component is represented by the general formula (Pb _m Ca _1-m ) (Sn _1-o Z
r _o ) O ₃ , m and o are in the region having the following a, b, c, and d as vertices in the m-o plane (except on the line of o = 1.0). a; m = 0.7 o = 1.0 b; m = 0.78 o = 1.0 c; m = 0.94 o = 0.25 d; m = 0.9 o = 0.25

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 composed mainly of lead oxide, calcium oxide, zirconium oxide and tin oxide used in the microwave region.

[0002]

2. Description of the Related Art Microwave dielectrics used in mobile communication devices using microwaves, such as car phones and mobile phones, have a high dielectric constant and are useful for downsizing equipment. In order to be able to use it, it is required to have a large unloaded Q value, and the dielectric characteristics should not change in the usage environment (especially temperature), and these three requirements must be achieved at the same time.

Since the wavelength of the electromagnetic wave is shortened to 1 / √ε _r in the dielectric body, the increase of the dielectric constant is useful for downsizing the communication device. The increase in communication volume gradually raises the frequency band used, narrows the frequency range per line, and the weight restriction due to miniaturization makes it difficult to secure communication time. Therefore, stability of the resonance frequency and a large unloaded Q value are required.

As a high dielectric constant microwave dielectric having such characteristics, a BaO--TiO ₂ --La system (here,
La is made of lanthanoid oxide such as Nd and Sm), and has a relative dielectric constant of about 90 and a small temperature coefficient.

However, the recent movement toward miniaturization of communication equipment using microwaves requires characteristics exceeding the BaO—TiO ₂ —La type conventional material having a relative dielectric constant of about 90. At the same time, there is a need for a material that has a large unloaded Q value and a small temperature coefficient. A composition having such characteristics is disclosed in JP-A-4-192209.
There is a porcelain composition described in the publication. When this porcelain composition is represented by the composition formula (Pb _1-x Ca _x ) Zr _1-y Sn _y O ₃ , x and y are the following points A on the xy plane:
It is in a rectangular area having B, C, and D as vertices. A; x = 0.3 y = 0.0 B; x = 0.5 y = 0.0 C; x = 0.4 y = 0.6 D; x = 0.25 y = 0.6 The porcelain composition in this region has a relative dielectric constant of 110.
It is just before and after, and it is hard to say that it far exceeds the characteristics of conventional materials.

On the other hand, in order to satisfy the above three characteristics at the same time, it has been attempted to integrally sinter and bond various compositions, but the composition thus obtained has a problem in uniformity and has not yet been put to practical use. .

[0007]

An object of the present invention is to provide a dielectric material having a higher permittivity than that of the conventional material and having a temperature coefficient τ _{f of the} resonance frequency which can be adjusted to around 0 ppm / ° C. Another object of the present invention is to provide a microwave dielectric material having a high dielectric constant and an unloaded Q value that can be practically used in the microwave region.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention further studied in the above-mentioned Japanese Unexamined Patent Publication (Kokai) No. 4-192209, where "a desirable characteristic as a microwave dielectric cannot be obtained." Specifically, for a composition represented by the general formula (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) O ₃ , the composition ratio of Sn and Zr is set as a predetermined value, and the ratio of Pb and Ca is When changing, the temperature coefficient τ _f of the resonance frequency tends to become a positive value from a negative value to ± 0 and cross a ± 0 value again to become a negative value as the ratio of Pb increases. Was discovered (see FIG. 2). The relative permittivity in the ratio of Pb and Ca near the point where τ _f crosses ± 0 again and reaches a negative value again is Pb.
It has been found that the higher the ratio of (3), the more it tends to increase (see FIG. 3). In this case, the unloaded Q value tends to decrease as the Pb ratio increases (see FIG. 4), but in the microwave dielectric filter used in a relatively low frequency region, the value is within a sufficiently allowable range. I found out that there is. The present invention has been completed based on the discovery of such facts.

Therefore, the dielectric porcelain composition of the present invention is a dielectric porcelain composition comprising lead oxide, calcium oxide, zirconium oxide and tin oxide, and the composition ratio of each component is represented by the general formula (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) O ₃ , m and o are in the region having a, b, c, and d as vertices below in the m-o plane (provided that o is
= Except for the line of 1.0). a; m = 0.7 o = 1.0 b; m = 0.78 o = 1.0 c; m = 0.94 o = 0.25 d; m = 0.9 o = 0.25

More preferable regions within the above-mentioned regions having a, b, c and d as vertices (except on the line of o = 1.0) are the following a ', b', c ', d'. Is a region having vertices or / and regions having vertices e, f, g and h (except on the line of o = 1.0). a '; m = 0.745 o = 1.0 b'; m = 0.76 o = 1.0 c '; m = 0.875 o = 0.5 d'; m = 0.865 o = 0 .5 e; m = 0.905 o = 0.325 f; m = 0.92 o = 0.325 g; m = 0.925 o = 0.275 h; m = 0.91 o = 0.275

[0011]

A porcelain composition based on the perovskite structure of lead zirconate represented by the general formula PbZrO _{3, in} which some sites of Pb are replaced by Ca and some sites of Zr are replaced by Sn. The dielectric ceramic composition of the present invention having the above composition range exhibits characteristics far superior to conventional materials in the microwave region. That is, the dielectric ceramic composition having the above composition range has a relative dielectric constant of 100 or more,
Moreover, the temperature coefficient τ _{f of the} resonance frequency is smaller than 100 ppm / ° C., and the unloaded Q value is large in the microwave region.

It should be noted that some of the ions of the present invention represented by (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) O ₃ are used as Pb and Ca site ions, and some or all of Ca is Sr, One or more of Ba or Mg, and / or Zr of Sn, Zr site ion
Even if a part or all of the above is replaced with one or more of Ti or Hf, a tendency similar to the characteristics of the porcelain composition of the present invention can be expected, and the temperature coefficient τ _f of relative permittivity in the high permittivity region is 0.
It can be adjusted to around ppm / ° C.

In the present invention, the composition of the general formula (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) O _{3 is represented} by the general formula (Pb _m Ca _1-m ) _x (Sn _1-o Zr _o ). When represented by O ₃ , if x is in the range of 0.94 ≦ x ≦ 1.06, it does not hinder the skeleton of the perovskite structure of the porcelain composition, so that practical dielectric properties are maintained and the composition in this range is maintained. Products are also included in the scope of the composition of the present invention.

[0014]

EXAMPLES Lead oxide (PbO), calcium carbonate (CaCO ₃ ), tin oxide (SnO ₂ ) and zirconium oxide (ZnO ₂ ) having a purity of 99.8% or higher were used as starting materials, and the composition ratios shown in Table 1 were used. Weigh so that These weighed powders are wet mixed with a ball mill for 20 hours (pure water is used as a medium). After this is dried, it is packed in a magnesia sagger with a lid and calcined in an air atmosphere at a temperature of 700 ° C to 1,000 ° C for about 3 hours. Calcination powder again in the ball mill 2
Wet mill for 0 hours. After the pulverized powder is dried, an appropriate amount of binder (polyvinyl alcohol) is added and kneaded, and the mixture is sized through a 35-mesh sieve. Next, it is molded into a disk shape (14φ, thickness 7 mm) with a molding pressure of 3 ton / cm ² . This molded body is heat-treated at 600 ° C. for 1 hour to be degreased, then embedded in co-powders in a magnesia sagger with a lid, and fired for 3 hours at a temperature of 850 ° C. to 1,550 ° C. depending on the composition in the air atmosphere. If lead evaporates on the surface of the fired product, remove the surface by grinding.

The dielectric properties of the obtained sintered body were measured by Hakki-Colema
The relative permittivity ε _r and the unloaded Q value were determined by the method described above (here, since the unloaded Q value and the resonance frequency (f) are approximately inversely proportional, Is shown as Qf value). The resonance frequency was 2 to 7 GHz. The resonance frequency temperature coefficient τ _f was obtained by averaging the resonance frequency temperature coefficients at −30 ° C. and 80 ° C. with reference to the resonance frequency of 25 ° C. The results are shown in Table 1.

[0016]

[Table 1]

Note that tin oxide (SnO ₂ ) may interfere with the firing of the composition. In such a case, CaS
Even when added in the form of nO ₃ , the same characteristics as when an oxide is used as a starting material can be expected.

As is apparent from Table 1, in the compositions within the composition range of the present invention (Examples 1 to 10), the relative dielectric constant was 1.
It is as high as 00 or more, the Qf value is 800 or more, and the absolute value of the resonance frequency temperature coefficient is 100 ppm / ° C. or less, and it is understood that the dielectric composition for microwaves has excellent characteristics. On the other hand, in the compositions outside the composition range of the present invention (Comparative Examples 11 to 21), the relative dielectric constant was 100.
It is either less than or equal to, the Qf value is less than or equal to 700, or the absolute value of the temperature coefficient of the resonance frequency exceeds 100 ppm / ° C., which is not desirable as a dielectric composition for microwaves.

FIG. 1 is a graph showing the composition range of the dielectric ceramic composition of the present invention, and the shaded region is the composition range of the present invention. The numbers shown in the figure correspond to the numbers in Table 1.

FIG. 2 is a graph showing the relationship between the composition and the temperature coefficient τ _{f of the} resonance frequency. In the composition formula (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) O ₃ , o is a predetermined value. Shows the changes in the resonance frequency temperature coefficient τ _f in the compositions in which m is variously changed.
As can be seen from FIG. 2, the resonance frequency temperature coefficient τ _f is m
Shows a negative value when is less than around 0.6 to 0.7,
m crosses ± 0 in the vicinity of 0.6 to 0.7, and when m further increases, it becomes a positive value and gradually increases as m increases and reaches a peak, then crosses ± 0 again and becomes negative. It can be seen that there is a tendency that the value becomes.

FIG. 3 is a graph showing the relationship between the composition and the relative permittivity ε _r . Similarly to the case described with reference to FIG. 2, the relative permittivity ε of the composition in which m is variously changed with the predetermined value of o. _This shows how _r changes. Resonance frequency temperature coefficient τ in FIG.
_In the region where _f shows a positive value from ± 0, reaches a peak, and crosses ± 0 again, the relative permittivity ε _r continues to increase as m increases, reaches a peak, and then gradually decreases. There is. It can be seen that ε _r exhibits a high value of approximately 100 or more in this region.

FIG. 4 is a graph showing the relationship between the composition and the Qf value, and shows how the Qf value changes in a composition in which o is a predetermined value and m is variously changed. As can be seen from FIG. 4, the Qf value tends to decrease in the region where m is 0.7 or more, but the Qf value still shows a high value, and there is a range in which the value is acceptable as a dielectric used in the microwave region. I understand.

From these facts, the absolute value of τ _f is 10
0ppm / ℃ or less, ε _r is 100 or more and Qf value is 800
By selecting the composition region showing the above values at the same time,
It can be seen that an excellent microwave dielectric composition can be obtained.

[0024]

The dielectric ceramic composition according to the present invention comprises lead oxide, calcium oxide, zirconium oxide and tin oxide, and its composition ratio is limited to a predetermined range.
It is a high dielectric constant material having a high relative permittivity and a small resonance frequency temperature coefficient τ _f , and can be used in a high frequency band. By using the dielectric ceramic composition of the present invention for a dielectric resonator, a substrate, etc., it is possible to realize further miniaturization of a microwave communication device, and its industrial value is great.

[Brief description of drawings]

FIG. 1 is a graph showing a composition range of a dielectric ceramic composition of the present invention.

FIG. 2 is a graph showing the relationship between composition and resonance frequency temperature coefficient τ _f .

FIG. 3 is a graph showing the relationship between composition and relative permittivity ε _r .

FIG. 4 is a graph showing the relationship between composition and Qf value.

[Procedure amendment]

[Submission date] September 3, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Within the above-mentioned region having a, b, c, and d as vertices (except on the line of o = 1.0), more preferable regions are the following a ′, b ′, c ′, and d ′. Is a region having vertices or / and regions having vertices e, f, g and h (except on the line of o = 1.0). a '; m = 0.745 o = 1.0 b'; m = 0.76 o = 1.0 c '; m = 0.875 o = 0.5 d'; m = 0.865 o = 0 .5 e; m = 0.905 o = 0.325 f; m = 0.92 o = 0.325 g; m = 0.925 o = 0.275 h; m = 0.91 o = 0.275 In the area with these a ', b', c ', d'as vertices
Resonance frequency is especially high in the region with vertices e, f, g, and h.
The temperature coefficient τ _{f of the} number is near 0,
This is preferable because it can be suppressed to be small.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

A porcelain composition based on the perovskite structure of lead zirconate represented by the general formula PbZrO _{3 in} which some sites of Pb are replaced by Ca and some sites of Zr are replaced by Sn. The dielectric ceramic composition of the present invention having the above composition range exhibits characteristics far superior to conventional materials in the microwave region. That is, the dielectric ceramic composition having the above composition range has a relative dielectric constant of 100 or more and an absolute value of the temperature coefficient τ _f of the resonance frequency of 100 p.
It also has the characteristics that it is pm / ° C. or less and that the unloaded Q value is large in the microwave region (specifically, the Qf value is 800 or more) .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Examples 1 to 10 and ratios shown in Table 1 above
Plot the composition of the compositions of Comparative Examples 11-21 on a graph
Then, it becomes as shown in FIG. Where the numbers shown in the figure
Corresponds to the number shown in Table 1. And shown in Table 1
As can be seen from the dielectric property values obtained,
In the product, the absolute value of the temperature coefficient τ _f of the resonance frequency is 100.
ppm / ° C or less, relative permittivity ε _r of 100 or more, no load Q
The value (Qf value) simultaneously satisfies the characteristic value of 800 or more,
The τ _f , ε _r , and Qf values for the limit values of these dielectric properties
Can afford. Therefore, the compositions of Examples 1 to 10 are
In the range close to the composition of Examples 1 to 10, that is, in FIG.
A region surrounded by a line connecting a, b, c, d is defined (a, b,
The values of m and o in c and d are the same as those described above. ),
The compositional area of the composition of the present invention was defined as this.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasue Ishiguro 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd.

Claims (1)

[Claims] 1. A dielectric ceramic composition comprising lead oxide, calcium oxide, zirconium oxide and tin oxide, wherein the composition ratio of each component is represented by the general formula (Pb _m Ca _1-m ) (Sn _1-o Zr _o ) When represented by O ₃ , m and o are in the region having the following a, b, c, and d as vertices in the m-o plane (provided that o is
= Except 1.0 on the line). a; m = 0.7 o = 1.0 b; m = 0.78 o = 1.0 c; m = 0.94 o = 0.25 d; m = 0.9 o = 0.25