JP3274950B2 - Dielectric ceramic composition and dielectric resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a mobile telephone,
The present invention relates to a dielectric ceramic composition and a dielectric resonator suitable for a resonator or a circuit board material in a microwave region mounted on a cordless telephone, a personal wireless device, and a satellite broadcast receiver.

[0002]

2. Description of the Related Art In recent years, automobile telephones, cordless telephones,
With the practical use of personal radios and satellite broadcasting receivers, dielectric porcelain in the microwave region has been widely used. Such a microwave dielectric porcelain is mainly used for a resonator, and the characteristics required therefor are as follows: (1) Since the wavelength is reduced to 1 / εr ^1/2 in a dielectric, there is a demand for miniaturization. (2) low dielectric loss at high frequency, that is, high Q value, and (3) small change of resonance frequency with temperature, that is, temperature of relative dielectric constant Mainly, the above three characteristics are small in dependence and stable.

Conventionally, as this type of dielectric ceramic, for example, BaO-TiO ₂ based materials, BaO-REO-TiO ₂ (where, REO is a rare earth element oxide) material, MgTiO ₃ - CaTiO ₃ system material such as Oxide porcelain materials are known (see, for example,
0806, JP-A-63-100058, JP-A-60-19603, etc.).

[0004]

[Problems to be solved by the invention] However, BaO-Ti
In the case of an O ₂ -based material, the relative dielectric constant εr is as high as 37 to 40 and the Q value is as large as 40000. However, it is difficult to obtain a single phase having a temperature coefficient τf of the resonance frequency of zero. Since the temperature dependence of the dielectric constant greatly changes, it is difficult to stably reduce the temperature coefficient τf of the resonance frequency while maintaining a high relative dielectric constant and a low dielectric loss.

[0005] In addition, BaO-REO-TiO ₂ materials
Nd ₂ O ₃ -TiO ₂ -based or Ba0-Sm ₂ O ₃ -Ti0 but ₂ system and the like are known, in these systems is the relative dielectric constant εr very high as 40-60, and the temperature coefficient of resonant frequency Although a sample having τf of zero is obtained, the Q value is as small as 5000 or less.

Further, in the case of the MgTiO ₃ -CaTiO ₃ based material, a material having a large Q value of 30,000 and a temperature coefficient τf of the resonance frequency of zero is obtained, but the relative dielectric constant εr is as small as 16 to 25.

As described above, none of the above-mentioned materials sufficiently satisfies the above three characteristics required for a high-frequency dielectric material.

The present inventors have proposed a dielectric porcelain that satisfies the above three characteristics, namely, Ln ₂ O _x —Al ₂ O ₃ —CaO—TiO.
_Two systems have been developed and previously disclosed in JP-A-6-76633. The _{Ln 2 O X -Al 2 O 3} -CaO-TiO
_In the high frequency dielectric materials of the ₂ series, compared to the above materials,
The relative dielectric constant εr and the Q value are high, and the temperature coefficient τf of the resonance frequency is also good.

However, in recent years,
A material having a high Q value and a good temperature coefficient τf of the resonance frequency is required to have a high relative dielectric constant εr and good sinterability for the purpose of miniaturization. ₂ O _X -Al ₂ O ₃ remains dielectric constant in -CaO-TiO ₂ system, Q value and sinterability is not sufficient.

The present invention has been made in view of the above-mentioned drawbacks, and is based on the conventional Ln ₂ O _x -Al ₂ O ₃ -CaO-TiO _2.
The dielectric constant is larger than the system, the Q value is high, the temperature dependence of the dielectric constant is small, and the sinterability is excellent. In addition, the relative dielectric constant is 32 or more, the Q value is 14000 or more, and the temperature of the resonance frequency is An object of the present invention is to provide a dielectric ceramic composition and a dielectric resonator having a coefficient τf within 30 ppm / ° C. and a porosity of 3% or less.

[0011]

Means for Solving the Problems The present inventors have repeatedly studied the above problems, and as a result, a system comprising Ln ₂ O _X , Al ₂ O ₃ , CaO and TiO ₂ (Ln is at least one kind or more) Is added to SrO and / or BaO in a rare earth element of 3 ≦ x ≦ 4), and by adjusting them to a specific range, the conventional Ln ₂ O _x —Al ₂ O ₃ —C
The relative permittivity is larger than that of the aO-TiO ₂ system,
It has been found that a dielectric ceramic composition having a small temperature dependence of the relative dielectric constant and excellent in sinterability can be obtained.

That is, the dielectric porcelain composition of the present invention comprises rare earth elements (Ln), Al, Ca and Ti as metal elements.
ALn ₂ O _x · bA
When expressed as l ₂ O ₃ .cCaO.dTiO ₂ , a, b,
When the values of c, d and x are a + b + c + d = 1, 0.05
6 ≦ a ≦ 0.214, 0.056 ≦ b ≦ 0.214,
0.286 ≦ c ≦ 0.500, 0.23 <d <0.47
0, SrO and / or BaO are added in an amount of 0.01 to 0.10 with respect to 100 mole parts of the main component satisfying 3 ≦ x ≦ 4.
It is desirable that the porosity is 3% or less. Further, it is desirable that SrO and / or BaO be contained in an amount of 0.05 to 0.10 mol part.

In the dielectric resonator according to the present invention, a dielectric porcelain is arranged between a pair of input / output terminals, and the dielectric porcelain operates by electromagnetic field coupling. Contains rare earth elements (Ln), Al, Ca and Ti, and these components are mixed in a molar ratio of aLn ₂ O
_x · bAl ₂ O ₃ · cCaO · dTiO ₂ ,
When the values of a, b, c, d and x are a + b + c + d = 1,
0.056 ≦ a ≦ 0.214, 0.056 ≦ b ≦ 0.2
14, 0.286 ≦ c ≦ 0.500, 0.23 <d <
SrO and / or BaO are added in an amount of 0.01 to 100 mol parts of the main component satisfying 0.470 and 3 ≦ x ≦ 4.
0.10 mol part is contained, and the porosity is desirably 3% or less. It is desirable that SrO and / or BaO be contained in an amount of 0.05 to 0.10 mol part.

The dielectric ceramic composition of the present invention contains a rare earth element (Ln), Al, Ca, Ti, Sr and / or BaO as a metal element. The reason for limiting these compositions to the above range is as follows. It is as follows.

That is, Ln ₂ O _x amount a is set to 0.0560 ≦ a
≦ 0.214 is used when 0.0560> a or a
This is because the Q value decreases when> 0.214. In particular, 0.0790 ≦ a ≦ 0.1700 is preferable.

As rare earth elements (Ln), Y, La,
Ce, Pr, Sm, Eu, Gd, Dy, Er, Yb, N
d, among which Nd is the best. In the present invention, two or more rare earth elements (Ln) may be used. From the viewpoint of the temperature dependence of the relative permittivity, Y, Ce, P
r, Sm, Eu, Gd, Dy, Er, and Yb are preferred.

The amount b of Al ₂ O ₃ is 0.0560 ≦ b
≦ 0.214 is used when 0.0560> b or b
This is because the Q value decreases when> 0.214. In particular, 0.0790 ≦ b ≦ 0.1700 is preferable.

Further, the CaO amount c is set to 0.286 ≦ c ≦
The reason for setting the value to 0.500 is that when c> 0.5000, the absolute value of the temperature coefficient τf of the resonance frequency exceeds 30 ppm / ° C., and when it is smaller than 0.286, the Q value becomes It is because it falls. CaO amount c is 0.39
It is desirable that ≦ c ≦ 0.47.

When the TiO ₂ amount d is 0.2300 <d <0.4
700 is set when 0.2300 ≧ d or d ≧ 0.
This is because in the case of 4700, the Q value decreases. In particular, 0.3333 ≦ d ≦ 0.3836 is preferable.

SrO and / or BaO are added in an amount of 0.01 to 0.1 to 100 mol parts of the main component having the above composition.
One mole part of SrO and / or BaO
This is because the effect of improving the Q value and the relative dielectric constant is small when the amount of addition of SrO is 0.01 mol part or less, and when the addition amount is more than 0.1 mol part, the Q value is smaller than before addition of SrO and BaO. Is reduced. The content of SrO and / or BaO is desirably 0.05 to 0.1 mol part in order to improve the Q value, the relative dielectric constant, and the sinterability.
SrO alone or BaO alone or SrO and Ba
O may be used. SrO is desirable because of its high Q value.

In the present invention, the porosity is desirably 3% or less, because when the porosity is more than 3%, the effect of improving the relative dielectric constant and the Q value is small. The porosity is desirably 2% or less. However, when the porosity is 2% or less, the relative dielectric constant and Q
This is because the value can be further improved, and thereby the volume of the porcelain required for obtaining the desired characteristics can be significantly reduced, and the size of the resonator can be reduced. The porosity is desirably 1% or less for improving the relative dielectric constant and the Q value. In order to reduce the porosity, it is effective to increase the green density of the compact. For this purpose, for example, when forming a molded body by press molding, it is effective to increase the pressing pressure. In the present invention, the porosity is 1 μm per unit area.
The void area ratio was determined from the average diameter of voids having a diameter of at least m and the number thereof.

The dielectric porcelain composition of the present invention is characterized in that ZnO, NiO, SnO ₂ , Co ₃ O
₄ , MnCO ₃ , ZrO ₂ , WO ₃ , LiCO ₃ , Rb
₂ CO ₃ , Sc ₂ O ₃ , V ₂ O ₅ , CuO, SiO ₂ ,
MgCO ₃ , Cr ₂ O ₃ , B ₂ O ₃ , GeO ₂ , Sb ₂
A composition to which O ₅ , Nb ₂ O ₅ , Ta ₂ O _5, or the like is added may be used as a main component. These may be added in a proportion of 6 parts by weight or less based on 100 parts by weight of the composition, depending on the added components. Among these, especially Nb
_When 1 to 4 parts by weight of ₂ O ₅ and Ta ₂ O ₅ is added, the relative dielectric constant is improved and the temperature characteristic is reduced as compared with the case where no addition is made.
, A dielectric ceramic excellent in performance can be obtained.

The dielectric ceramic composition of the present invention is prepared, for example, as follows. As starting materials, powders of strontium carbonate and / or barium carbonate, high-purity rare earth oxide, aluminum oxide, titanium oxide, and calcium carbonate are weighed to a desired ratio. Powders such as Nb ₂ O ₅ , Ta ₂ O ₅ and ZnO may be added to these. After that, pure water is added, and the mixture is mixed until the average particle size of the mixed raw material becomes 1.6 μm or less.
The wet mixing / pulverization is performed by a mill using zirconia balls or the like for 0 to 30 hours. After drying this mixture, 110
Calcination at 0 to 1300 ° C for 1 to 4 hours, then 0.8 to 5
After adding the binder by weight and sieving, the obtained powder is formed into an arbitrary shape by a desired forming means, for example, a die press, a cold isostatic press, an extrusion molding or the like.
It is obtained by baking in air at a temperature of 0 to 1700 ° C. for 1 to 10 hours.

Further, the dielectric resonator according to the present invention is, for example,
In the TE mode resonator shown in FIG. 1, an input terminal 2 and an output terminal 3 are formed on both sides of a metal case 1.
3, a dielectric porcelain 4 having the above-described composition is arranged. In such a TE mode type dielectric resonator, a microwave is input from the input terminal 2, and the microwave is confined in the dielectric porcelain 4 by reflection at a boundary between the dielectric porcelain 4 and free space, and a specific Resonates at frequency. This signal is electromagnetically coupled to the output terminal 3 and output. Although not shown, the dielectric ceramic composition of the present invention may be applied to a coaxial resonator, a stripline resonator using a TEM mode, a TM mode dielectric ceramic resonator, and other resonators. Of course.

[0025]

The dielectric porcelain composition of the present invention contains a rare earth element (Ln), Al, Ca, Ti, Sr and / or Ba as a metal element. Has a higher relative dielectric constant and Q value than a material that does not contain predetermined amounts of Sr and Ba,
The size of the resonator can be reduced. Further, since the sinterability is improved, it is possible to prevent the occurrence of cracks even when producing a large-sized sintered body.

Further, by setting the porosity to 3% or less, the relative dielectric constant and the Q value can be further increased, and the miniaturization of the resonator can be promoted.

Further, by using a dielectric porcelain having the above-described composition to produce a dielectric resonator that operates by electromagnetic field coupling, it is small in size, low in loss, and stable with use temperature. It is possible to obtain a resonance frequency.

The present invention is particularly suitable for a resonator using a large-sized dielectric porcelain. For example, even when a dielectric porcelain having a diameter of about 10 cm is produced, no crack is generated.

[0029]

【Example】

Comparative Example High purity rare earth oxide (Nd ₂ O ₃ ) as a starting material,
Aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ )
₂ ) and calcium carbonate (CaCO ₃ ) powders were weighed as shown in Table 1, pure water was added, and the mixture was milled until the average particle size of the mixed raw materials became 1.6 μm or less. Wet mixing and grinding were performed for hours. Depending on the type of mill balls and other various conditions, ZrO ₂ , SiO ₂ , and other rare earth element impurities may be contained in an amount of 1% by weight or less.

After drying this mixture, it is calcined at 1200 ° C. for 2 hours, and after adding about 1% by weight of a binder, sizing is performed. The obtained powder is formed into a disk at a pressure of about 1000 kg / cm ^2. It was molded and fired in the air at a temperature of 1500 to 1700 ° C. for 2 hours to obtain a porcelain having a diameter of 14 mm and a thickness of 8 mm.

The disk portion of the obtained porcelain was polished flat, ultrasonically washed in acetone, and dried at 150 ° C. for 1 hour.
The relative permittivity, the Q value, and the temperature coefficient τf of the resonance frequency were measured at a measurement frequency of 3.5 to 4.5 GHz by the cylindrical resonator method. The Q value was converted to a Q value at 1 GHz from a relationship that is generally established in a microwave dielectric × measurement frequency f = constant. The temperature coefficient τf of the resonance frequency is obtained by measuring the resonance frequency between −40 ° C. and + 85 ° C., and setting the temperature coefficient τ of −40 ° C. to + 85 ° C. based on the resonance frequency at 25 ° C.
f was calculated. Table 1 shows the results.

[0032]

[Table 1]

In the above example, various rare earth oxides were used in place of Nd ₂ O ₃ , and the subsequent conditions were the relative permittivity, Q value, and temperature coefficient of the resonance frequency of the porcelain produced in the same manner as above. τf was measured in the same manner as above, and the results are shown in Table 2.

[0034]

[Table 2]

Table 1 shows the main components No. 33 to 42.
No. 8 in No. 8 and Nos. 43 to 45 in Table 1.
The compositions of No. 7 and Nos. 46 to 48 are the cases where Nd ₂ O ₃ of the composition of No. 10 in Table 1 was replaced with another rare earth element oxide.

Further, various metal oxides were added to 100 parts by weight of the composition of No. 8 in Table 1, and the subsequent conditions were the relative permittivity, Q value, The temperature coefficient τf of the resonance frequency was measured in the same manner as described above, and the results are shown in Tables 3 and 4.

[0037]

[Table 3]

[0038]

[Table 4]

Example 1 High purity rare earth oxide (Nd ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO ₃ )
₃ ) Each powder of barium carbonate (BaCO ₃ ) was weighed as shown in Tables 5-7. In the tables, the main component No. means the main components No. in Tables 1-4. Thereafter, pure water was added, and wet mixing / pulverization was performed for about 20 hours by a mill until the average particle size of the mixed raw material became 1.6 μm or less. Depending on the type of mill ball and various other conditions,
ZrO ₂ , SiO ₂ , or other rare earth element impurities
% By weight or less.

After drying this mixture, it is calcined at 1200 ° C. for 2 hours, and after adding about 1% by weight of a binder, sieving is performed. The obtained powder is formed into a disk at a pressure of about 1000 kg / cm ^2. It was molded and fired in the air at a temperature of 1500 to 1700 ° C. for 2 hours to obtain a porcelain having a diameter of 14 mm and a thickness of 8 mm.

The disc portion of the obtained porcelain was polished flat, ultrasonically washed in acetone, and dried at 150 ° C. for 1 hour.
The relative permittivity, the Q value, and the temperature coefficient τf of the resonance frequency were measured at a measurement frequency of 3.5 to 4.5 GHz by the cylindrical resonator method. The Q value was converted to a Q value at 1 GHz from a relationship that is generally established in a microwave dielectric × measurement frequency f = constant. The temperature coefficient τf of the resonance frequency is obtained by measuring the resonance frequency between −40 ° C. and + 85 ° C., and setting the temperature coefficient τ of −40 ° C. to + 85 ° C. based on the resonance frequency at 25 ° C.
f was calculated. In addition, the porcelain surface is mirror-polished, the mirror surface is magnified 400 times with a microscope, and the void area ratio is determined from the average diameter and the number of voids having a void diameter of 1 μm or more within an area of 500 μm × 500 μm. Was defined as the porosity. The results are shown in Tables 5 to 7. In the table, the porosity P is 0
● <P ≦ 1%, 1% <P ≦ 2%, ○ 2
% <P ≦ 3%, and x when 3% <P.

[0042]

[Table 5]

[0043]

[Table 6]

[0044]

[Table 7]

From these tables, when SrO and BaO are added in an amount of 0.01 to 0.1 mol parts per 100 mol parts of the main component, the results are compared with the case where the conventional SrO and / or BaO is not added. Thus, it can be seen that the relative permittivity and the Q value are improved.

The present inventors visually checked samples Nos. 19 to 29 and samples Nos. 32 to 37 as to whether or not cracks occurred during the manufacturing process. The cracks were 60 mm in diameter and 30 m in thickness as described above.
m was prepared as a sample. The crack had a crack end on the surface and a length of 5 mm or more. The results are shown as graphs in FIGS. 2 is a graph of Sample Nos. 19 to 29, and FIG.
It is a graph of. The vertical axis of the graph indicates the number of cracks during the manufacture of 20 pieces of porcelain, and the horizontal axis indicates Sr, B
Shows the amount a. From these graphs, it can be seen that the sample of the present invention has improved sinterability, improved strength, and is less likely to crack during production.

We have added 0.05 mol part of SrO,
As a result of an experiment in which 0.05 mol part of BaO was added to the main component No. 8 in Table 1 and the press pressure was 1 ton / cm ² , the relative dielectric constant was 45, the Q value was 48,000, and the temperature coefficient of the resonance frequency was 4 Was -45 and 85 ° C, respectively. The porosity was 1-2%.

Example 2 The present inventors have found that the main component of Example 1 is Nd ₂ O
Various rare earth oxides are used in place of ₃ , and the subsequent conditions are as follows:
The relative permittivity, the Q value, and the temperature coefficient τf of the resonance frequency of the porcelain prepared in the same manner as above were measured in the same manner as above, and the results are shown in Table 8 as samples Nos. 76 to 91. The sample N
Nos. 76 to 85 have the composition of Sample No. 8 in Table 1, samples 86 to 88 have the composition of Sample No. 7 in Table 1, and samples 89 to 91 have the composition of Sample No. 1 in Table 1. An experiment was conducted with the composition of .10, except that Nd of Nd ₂ O ₃ was replaced with another rare earth element as shown in Table 2.

[0049]

[Table 8]

From Table 8, it can be seen that Nd ₂
When other rare earth oxides are used instead of O ₃ , SrO
And / or when BaO is added in an amount of 0.01 to 0.1 mol part, the relative dielectric constant and the Q value are improved as compared with the case where conventional SrO and / or BaO are not added. I understand.

Example 3 The present inventors further used the powders of strontium carbonate (SrCO ₃ ) and / or barium carbonate (BaCO ₃ ) with respect to the main components shown in Tables 3 and 4 to obtain them in Table 8. Of the porcelain prepared in the same manner as in the first embodiment, the relative permittivity, the Q value, and the temperature coefficient τf of the resonance frequency of the porcelain prepared in the same manner as in the first embodiment. The measurement was performed in the same manner as in Example 1, and the results are shown in Tables 8 and 9.

[0052]

[Table 9]

According to Tables 8 and 9, when SrO and / or BaO are added and contained in an amount of 0.01 to 0.1 mol part, compared to the case where conventional SrO and / or BaO is not contained, It can be seen that the relative permittivity and the Q value are improved.

[0054]

As described above in detail, the dielectric porcelain composition of the present invention has a rare earth element (Ln), A
containing l, Ca, Sr and / or Ba, Ti, by adjusting these to a specific range,
Higher relative dielectric constant, higher Q value, and lower temperature coefficient of resonance frequency at high frequencies than the conventional dielectric ceramic composition not containing 0.01 to 0.1 mol part of Sr and / or Ba. It can have dielectric properties. Therefore, a material which is satisfactory for use as a resonator or a circuit board material used at a high frequency can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a dielectric resonator of the present invention.

FIG. 2 is a graph showing the relationship between the amounts of Sr and Ba of Samples Nos. 19 to 29 and the number of cracked porcelains when manufacturing 20 porcelains of the present invention.

FIG. 3 is a graph showing the relationship between the amount of Sr in samples Nos. 32 to 37 and the number of cracked porcelains when manufacturing 20 porcelains of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal case 2 ... Input terminal 3 ... Output terminal 4 ... Dielectric porcelain

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-76633 (JP, A)

Claims (6)

(57) [Claims] A rare earth element (Ln), A as a metal element
l, comprises a Ca and Ti, when represented as _{aLn 2 O x · bAl 2 O} 3 · cCaO · dTiO 2 in a molar ratio of these components, a, b, c, the values of d and x are a + b + c + d = 1 0 0.056 ≤ a ≤ 0.214 0.056 ≤ b ≤ 0.214 0.286 ≤ c ≤ 0.500 0.23 <d <0.470 3 ≤ x ≤ 4 with respect to 100 mole parts of the main component A dielectric porcelain composition containing 0.01 to 0.10 mol parts of SrO and / or BaO. 2. The dielectric ceramic composition according to claim 1, wherein the porosity is 3% or less. 3. The method according to claim 1, wherein SrO and / or BaO is 0.05 to
3. The dielectric porcelain composition according to claim 1, which contains 0.10 mol part. 4. A dielectric resonator having a dielectric ceramic disposed between a pair of input / output terminals and operated by electromagnetic field coupling, wherein said dielectric ceramic has a rare earth element (L) as a metal element.
n), Al, containing Ca and Ti, when represented as _{aLn 2 O x · bAl 2 O} 3 · cCaO · dTiO 2 in a molar ratio of these components, a, b, c, the values of d and x are a + b + c + d = 1 0.056 ≤ a ≤ 0.214 0.056 ≤ b ≤ 0.214 0.286 ≤ c ≤ 0.500 0.23 <d <0.470 3 ≤ x ≤ 4 100 mol of main component A dielectric resonator containing SrO and / or BaO in an amount of 0.01 to 0.10 mol part per part. 5. The dielectric resonator according to claim 4, wherein the porosity is 3% or less. 6. SrO and / or BaO is 0.05 to
6. The dielectric resonator according to claim 4, which contains 0.10 mol part.