JPH0877828A - Dielectric ceramic composition and its manufacture - Google Patents

Abstract

PURPOSE: To provide such a dielectric ceramic composition as exhibits stable dielectric characteristics despite of calcining it under lower temperature than usual by mixing specific composition calcination powder of Ba-Sn-Ti-O systems. ZnO, etc., to specific composition calcination power of Ba-Mg-Ta-O system and calcining it. CONSTITUTION: Calcination powder of a formula III is mixed at the rate of 50mol. or less to calcination powder 100mol. of formula I or II, ZnO or MnCO3 is added at the rate of 5mol. or less to this calcination powder mixture 100mol., and after that it is calcined in the atmosphere or oxygen atmosphere under 1300 to 1650 deg.C so as to provide a target composition. This composition is a dielectric ceramic composition represented by a formula IV. In the formula, 0.20<=Z<=0.80; 0.00<x<=0.50; (y) represents mol. number of MnO and/or ZnO to 1mol. of the main component formula V.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric porcelain composition, and more particularly, to a dielectric porcelain composition which constitutes a resonator, a filter, a capacitor, a circuit board, etc. used mainly in the microwave band and its manufacture. Regarding the method.

[0002]

2. Description of the Related Art In recent years, high frequency dielectric porcelain has been used as an antenna duplexer and a voltage controlled oscillator (VC) for wireless communication equipment such as car phones, mobile phones and cordless phones.
It is often used for resonators used in O) or the like, or filters used for CATV tuners.
In such a resonator, by using a material with a high dielectric constant, the high-frequency wavelength can be controlled by ε _r in a vacuum.
^-1/2 (ε _r : relative permittivity) is shortened, and microwave of 1 wavelength, 1/2 wavelength, or 1/4 wavelength at such frequency is confined in high frequency dielectric ceramic parts, It is generally known to have a small size so as to obtain a predetermined effect.

The characteristics required for the high frequency dielectric ceramics are as follows: (1) The wavelength of the electromagnetic wave in the dielectric is ε _r ^-1/2
Since it can be miniaturized as the relative dielectric constant increases with the same resonance frequency, the relative dielectric constant should be as large as possible. (2) The dielectric loss in the high frequency band should be small, that is, the Q value should be large. And (3) the change rate of the resonance frequency due to temperature change is small, that is, the temperature dependence of the relative permittivity ε _r is small and stable.

Further, the microwave band mainly used at present is around 1 GHz for consumer appliances, but it is used in higher frequency bands (1 to several GHz) due to the increase in the amount of information and the faster operation of the appliances. There is an increasing need for microwave electronic components that can be used. Therefore, in order to reduce the microwave loss as much as possible, the dielectric ceramic composition constituting the microwave electronic component has a Q
A material having a large value is required, and a material having a large relative dielectric constant is required in order to reduce the size of the electronic component as much as possible.

Conventionally, many dielectric ceramic compositions having the above characteristics, such as BaO--TiO ₂ system and ZrTiO ₄ system, are known, and Ba (Mg _1/3 Ta _2/3 ) O ₃ is known.
System, Ba (Zn _1/3 Ta _2/3 ) O ₃ system, etc. are also known as one of them.

The characteristics required for these dielectric ceramic compositions are that the relative permittivity (ε _r ) and Q value are large as described above, and that the temperature coefficient (τ _f ) of the resonance frequency is close to zero. Besides, it is possible to control the variation in the temperature coefficient (τ _f ) depending on the material purity and the material lot to some extent.

[0007]

However, the conventional Ba (Mg _1/3 Ta _2/3 ) O ₃ system or Ba (Zn
_{With 1/3} Ta _2/3 ) O ₃ -based materials, although the Q value is large, the relative permittivity (ε _r ) is as small as 28 or less, making it difficult to miniaturize the element and controlling it to obtain sinterability. It was necessary to prepare the sample under the specified firing conditions. Furthermore, since these materials cannot control the temperature coefficient (τ _f ) of the resonance frequency as they are, the temperature coefficient of the resonance frequency (τ _f ) can be obtained by adding various additives such as rare earth elements.
_f ) had to be changed, but the characteristics at that time were not systematically examined, and there was the problem that it was not possible to easily supply a dielectric ceramic composition that met various required characteristics. .

The present invention has been made in view of the above problems and has a high Q value and a relative dielectric constant (ε _r ) and a temperature coefficient (τ _f ) of a resonance frequency of +150 to −150 pp.
It is an object of the present invention to provide a dielectric ceramic composition that can be controlled to any value within the range of m / ° C.

Further, a method for producing a dielectric porcelain composition which can obtain stable dielectric characteristics even at a firing temperature of 1300 to 1650 ° C. which is lower than the conventional one and can satisfy the characteristics required in high frequency communication devices and the like. Is intended to provide.

[0010]

In order to achieve the above object, a dielectric ceramic composition according to the present invention has a composition of Ba ((Mg / Z
_{n) 1/3 Ta 2/3) O 3} · xBa (Sn z Ti 1-z) O
₃ + y (MnO + ZnO) (where x, y and z are 0.00 <x ≦ 0.50, 0.00 ≦ y ≦ 0.05, respectively)
Values in the range of 0.20 ≦ z ≦ 0.80 are shown. y is the main component Ba ((Mg / Zn) _1/3 Ta _2/3 ) O ₃ · xBa (S
It shows the number of moles of MnO and / or ZnO with respect to 1 mole of n _z Ti _1-z ) O ₃ . ) Is a composition represented by. (1) The method for producing a dielectric ceramic composition according to the present invention is the method for producing a dielectric ceramic composition according to (1) above,
Ba (Mg _1/3 Ta _2/3 ) O ₃ or Ba (Zn _1/3
Ba (Sn _z Ti _1-z ) O ₃ (however, 0.2 with respect to 100 mol of the calcined powder of Ta _2/3 ) O ₃ at a ratio of 50 mol or less
0 ≦ z ≦ 0.80) of the calcined powder, and ZnO or MnCO is added to 100 mol of the calcined powder mixture.
_{It is characterized in that 3} is added at a ratio of 5 mol or less, and then fired at 1300 to 1650 ° C. in the air or an oxygen atmosphere. (2) The raw material powder used in the method for producing the dielectric ceramic composition is a powder selected from compounds containing Ba, Mg, Ta and Zn, and a powder selected from compounds containing Zn and / or Mn. The raw material powder is not limited to the oxide of the metal, and may be powder of carbonate, oxalate, nitrate, alkoxide or the like, as long as the target oxide can be obtained after firing. When the metal oxide or carbonate is used as a raw material powder, a preferable average particle diameter is about several μm, and these raw material powders are wet-mixed by a commonly-used method and further dried,
Calcination, crushing, granulation, molding, etc. are performed to produce a molded body having a predetermined shape, and then firing. The temperature for calcining and synthesizing the oxide or carbonate is preferably about 1000 to 1200 ° C. If the calcination temperature is less than 1000 ° C, a large amount of the raw material composition remains, which hinders uniform calcination.
If it exceeds 00 ° C, sintering will start, and it will be difficult to pulverize it, which will adversely affect the Q value. The structure of the dielectric ceramic composition produced by the above method has a substantially uniform grain size.

[0011]

According to the dielectric ceramic composition having the above structure, Ba
_{((Mg / Zn) 1/3 Ta} 2/3) O 3 · xBa (Sn z
Ti _1-z ) O ₃ + y (MnO + ZnO) (where x,
y and z are 0.00 <x ≦ 0.50 and 0.00 ≦, respectively.
Values in the range of y ≦ 0.05 and 0.20 ≦ z ≦ 0.80 are shown. y is the main component Ba ((Mg / Zn) _1/3 Ta _2/3 ) O
Mn for 1 mol of ₃ · xBa (Sn _z Ti _1-z ) O ₃
The number of moles of O and / or ZnO is shown. ), The relative dielectric constant (ε _r ) is 25 to 3
8 and the Q value is as large as 10,000 or more at the measurement frequency of 3 GHz, the dielectric loss is small, and the temperature coefficient (τ _f ) of the resonance frequency is +1 by changing the composition.
It becomes possible to control to a specific value within the range of 50 to -150 ppm / ° C.

In the above dielectric ceramic composition, the value of x is the molar ratio of Ba (Sn _z Ti _1-z ) O _{3 to} 100 mol of Ba ((Mg / Zn) _1/3 Ta _2/3 ) O _3. As shown, when the value of x is 0.00, the firing temperature becomes high and the relative permittivity (ε _r ) becomes small at 25 or less.
Dielectric properties such as values become unstable. On the other hand, the value of x is 0.5
When it is 0 or more, the Q value becomes as small as 10,000 or less (3 GHz), and it becomes difficult to use it as a resonator or the like.

The value of y is Ba ((Mg / Zn) _1/3 Ta
_2/3 ) O ₃ · xBa (Sn _z Ti _1-z ) O ₃ shows the molar ratio of MnO and / or ZnO with respect to 100 mol. When the value of y exceeds 0.05, the Q value becomes 100.
Temperature coefficient (τ _f ) becomes smaller than 00 (3 GHz)
Cannot be controlled to a specific value within the range of +150 to −150 ppm / ° C.

The value of z indicates the molar ratio of Sn to Ti. When the value of z is less than 0.20, the Q value becomes as small as 10000 or less (3 GHz), while the value of z is 0. If it exceeds 0.80, the temperature coefficient (τ _f ) of the resonance frequency cannot be controlled to a specific value within the range of +150 to −150 ppm / ° C.

According to the method for producing a dielectric ceramic composition described in (2) above, a temporary composition of Ba (Mg _1/3 Ta _2/3 ) O ₃ or Ba (Zn _1/3 Ta _2/3 ) O ₃ is used. Shokona 100 moles, at a ratio of 50 mol _{Ba (Sn z Ti 1-z} ) O 3
(However, 0.20 ≦ z ≦ 0.80) is mixed with the calcined powder,
Further, ZnO or MnCO ₃ was added at a ratio of 5 mol or less to 100 mol of the mixture of the calcined powder, and then 1300 to 1650 ° in the air or oxygen atmosphere.
Since firing is performed at C, the average crystal grain size of the sintered body is uniformly controlled, the relative dielectric constant (ε _r ) is as high as 25 to 38, and the Q value is as large as 10000 or more at the measurement frequency of 3 GHz, so that the dielectric loss is large. The temperature coefficient (τ _f ) of the resonance frequency is +150 to −150 pp by making it small and changing the composition.
A dielectric porcelain composition controlled to a specific value within the range of m / ° C. is produced.

In the method for producing the above-mentioned dielectric ceramic composition, if the firing temperature is less than 1300 ° C., the densification does not proceed sufficiently, the Q value becomes less than 10,000 (3 GHz), and the relative dielectric constant (ε _r ) Is not sufficiently high, and on the other hand, when the firing temperature exceeds 1650 ° C., the dielectric ceramic composition itself is softened and the shape of the molded body before firing cannot be retained.

[0017]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the dielectric ceramic composition and the method for producing the same according to the present invention will be described below.
First, a method for manufacturing a dielectric ceramic composition according to an example will be described.

BaCO ₃ , MgO or ZnO, Ta ₂ O ₅ , SnO ₂ , TiO ₂ , Mn having an average particle size of several μm.
Powders selected from CO ₃ are compounded at the ratios shown in Table 1-1 to Table 1-3. Here, x, y, and z shown in Tables 1-1 to 1-3 have the composition of the raw material powder of Ba ((Mg / Zn)).
_{1/3 Ta 2/3) O 3 · xBa} (Sn z Ti 1-z) O 3 +
Corresponds to x, y, and z when represented by y (MnO + ZnO).

First, each raw material powder was accurately weighed so as to have the ratio shown in Tables 1 and 2, and wet-mixed for 24 hours in a pot mill together with an appropriate amount of cobblestone, a known dispersant, and pure water. , To obtain a raw material powder mixture in the form of a slurry.
At this time, ZnO and / or MnC are used as sintering aids.
O ₃ may be added in the range of 0.00 to 5.00 mol with respect to 100 mol of the main component.

Next, the slurry-like raw material powder mixture is dehydrated and dried and then crushed.

Next, the crushed powder is transferred into a firing crucible made of, for example, zirconia, and calcined at 1000 ° C. for synthesis. Then, it is confirmed by composition analysis means such as x-ray analysis or ICP emission spectroscopy that the predetermined solid solution is synthesized.

Next, the calcined synthetic powder is crushed and sized to a uniform powder of about 1.0 μm. After the sizing is completed, an organic binder or the like is added to this powder to perform molding, and the diameter is 15
A disk-shaped molded body having a thickness of 8 mm and a thickness of 8 mm is produced.

Next, after degreasing the obtained molded body at 600 ° C., the degreased molded body is placed on, for example, a magnesia firing plate and fired in the air or in an oxygen atmosphere. The firing conditions are a firing temperature of 1300 to 1650 ° C. and a firing time of 2.0 to 8.0 hours.

Next, the sintered body obtained by the above-mentioned firing was thoroughly washed in pure water, and then polished so that the surfaces of the ceramics were parallel to each other and the resonance frequency was 3 GHz, and the sintered body was electrolyzed. To measure physical characteristics.

Although an oxide is used as a raw material in the present embodiment, the raw material is not limited to the oxide, and any carbonate, oxalate, nitrate or the like can be used as long as the target oxide can be obtained after firing. Anything is fine. Regarding the composition of the produced dielectric porcelain composition, the composition of the sintered body was confirmed by dissolving the dielectric porcelain composition obtained by firing in an acid and then performing ICP emission spectral analysis. Further, in order to observe the structure of the sintered body, an etching process was performed after the sintered body was broken, and a scanning electron microscope (SEM) was used.
As a result of observing the surface thereof, it was found that the dielectric ceramic composition according to the example had a dense structure formed of particles having a substantially uniform particle size.

Next, a method for measuring the electrical characteristics of the dielectric ceramic composition according to the example will be described.

The electrical characteristics were measured by using the resonance frequency, relative permittivity (ε _r ), and Q value by using The Post Resonance Technique proposed by Hakki-Coleman.

FIG. 1A is a plan view schematically showing an apparatus used for measuring the electric characteristics, and FIG. 1B is a front view of the apparatus.

A sample (dielectric ceramic composition) 11 to be measured is fixed in a state of being sandwiched between two parallel metal plates 12. Reference numeral 13 is a column for stabilizing the metal plate placed on the sample.

At the time of measuring the relative permittivity, a high frequency is oscillated from one probe 14 of the network analyzer to measure the frequency characteristic, and the relative permittivity (from the obtained resonance frequency peak of the TE01δ mode and the size of the sample 11 is measured ( ε _r ) was obtained. Further, the surface resistivity of the metal plate 12 is calculated using a standard sample, the dielectric loss of the metal plate 12 is calculated from this value, the dielectric loss of the metal plate 12 is removed from the overall dielectric loss value, and the Q value of sample 11 is calculated. I asked. Further, the temperature coefficient (τ _f ) of the resonance frequency was measured by changing the temperature of the atmosphere for measuring the resonance frequency from −30 to + 85 ° C.

Fifty samples for each example (composition) were manufactured for measurement, and the electrical characteristics of each sample 11 were measured, and the average value was calculated. The results are shown in Table 1.
-1 to Table 1-3.

As a comparative example, a dielectric ceramic composition having a composition outside the composition range of the present invention was produced under the same conditions as in the above-mentioned example, and the composition was within the range of the present invention.
The electrical characteristics of the dielectric ceramic composition produced by setting the firing temperature to a temperature lower than 0 ° C. or a temperature higher than 1650 ° C. were also measured. The results are also shown in Tables 1-1 to 1-3, and the comparative examples are marked with *. Note in the tables _{Ba (Mg 1/3 Ta 2/3} ) O 3 · xBa (Sn
A dielectric ceramic composition having a composition of _z Ti _1-z ) O ₃ + y (MnO + ZnO) is represented by Ba (Zn _1/3 Ta _2/3 ).
_{O 3 · xBa (Sn z Ti} 1-z) O 3 + y (MnO + Z
The dielectric ceramic composition has a composition of nO).

[0033]

[Table 1-1]

[0034]

[Table 1-2]

[0035]

[Table 1-3]

As is clear from the results shown in Tables 1-1 to 1-3, the relative dielectric constant (ε
_r ) is as high as 25 to 38, the Q value is as large as 10000 or more at the measurement frequency of 3 GHz, so that the dielectric loss is small and the temperature coefficient (τ _f ) of the resonance frequency is +150 to −150 ppm / by changing the composition. It can be controlled to a specific value within the range of ° C.

Further, by setting the firing temperature to 1300 ° C. to 1650 ° C., the dielectric ceramic composition having the above-mentioned excellent electrical characteristics can be produced.

On the other hand, in the dielectric ceramic composition according to the comparative example, x
When the value of is 0.00 or more than 0.50, the value of y is more than 0.05, and the value of z is less than 0.20 or more than 0.80, The electrical characteristics of at least one of Q value, relative permittivity (ε _r ) and temperature coefficient of resonance frequency (τ _f ) do not satisfy the above range, and it is difficult to use as a resonator. I understood.

The firing temperature is less than 1300 or 1650.
The electrical characteristics of the obtained dielectric ceramic composition were similarly unsatisfactory even for those exceeding the above range.

[0040]

As described above in detail, in the dielectric ceramic composition according to the present invention, Ba ((Mg / Zn) _1/3 T
a _2/3 ) O ₃ · xBa (Sn _z Ti _1-z ) O ₃ + y (M
nO + ZnO) (wherein x, y, and z are each 0.00)
<X ≦ 0.50, 0.00 ≦ y ≦ 0.05, 0.20 ≦
Values in the range of z ≦ 0.80 are shown. y is the main component Ba ((M
g / Zn) _1/3 Ta _2/3 ) O ₃ · xBa (Sn _z Ti
MnO and / or ZnO per 1 mol of _1-z ) O ₃
The number of moles of ), The relative permittivity (ε _r ) is as high as 25 to 38, and the Q value is as large as 10000 or more at the measurement frequency of 3 GHz, so that the dielectric loss is small and the composition etc. can be changed. Resonance frequency temperature coefficient (τ _f ) +150 to −150 ppm
It is possible to provide a dielectric ceramic composition that can be controlled to a specific value within the range of / ° C.

Further, by utilizing the characteristics of the dielectric ceramic composition as described above, it becomes possible to greatly reduce the size of a high frequency resonator, a filter and the like.

In the method for producing a dielectric ceramic composition according to the present invention, Ba (Mg _1/3 Ta _2/3 ) O ₃ or Ba (Zn _1/3 Ta _2/3 ) O ₃ is used. the calcined powder to 100 moles, at a ratio of 50 mol _{Ba (Sn z Ti 1-z} )
A calcined powder of O ₃ (however, 0.20 ≦ z ≦ 0.80) was mixed, and Zn was added to 100 mol of the mixture of the calcined powder.
O or MnCO ₃ is added at a ratio of 5 mol or less, and then 1300 to 165 in air or oxygen atmosphere.
Since firing is performed at 0 ° C, the average crystal grain size of the sintered body is uniformly controlled, the relative permittivity (ε _r ) is as high as 25 to 38, and the Q value is as large as 10000 or more at the measurement frequency of 3 GHz. The loss is small, and the temperature coefficient (τ _f ) of the resonance frequency is +150 to −150 by changing the composition.
A dielectric ceramic composition controlled to a specific value within the range of ppm / ° C. can be easily manufactured.

[Brief description of drawings]

FIG. 1 (a) is a plan view schematically showing an apparatus used for measuring electrical characteristics of a dielectric ceramic composition according to an example, and FIG. 1 (b) is a front view of the apparatus. .

[Explanation of symbols]

 11 Dielectric porcelain composition

Claims (2)

[Claims] 1. Ba ((Mg / Zn) _1/3 Ta _2/3 ) O
₃ x Ba (Sn _z Ti _1-z ) O ₃ + y (MnO + Zn
O) (where x, y, and z are 0.00 <x ≦ 0.
50, 0.00 ≦ y ≦ 0.05, 0.20 ≦ z ≦ 0.8
A value in the range of 0 is shown. y is the main component Ba ((Mg / Zn))
_{1/3 Ta 2/3) O 3 · xBa} (Sn z Ti 1-z) O 3 1
The number of moles of MnO and / or ZnO relative to the moles is shown. ) A dielectric ceramic composition having a composition represented by 2. Ba (Sn) at a ratio of 50 mol or less with respect to 100 mol of calcined powder of Ba (Mg _1/3 Ta _2/3 ) O ₃ or Ba (Zn _1/3 Ta _2/3 ) O _{3. z} Ti _1-z ) O ₃
(However, 0.20 ≦ z ≦ 0.80) is mixed with the calcined powder,
Further, ZnO or MnCO ₃ was added at a ratio of 5 mol or less to 100 mol of the mixture of the calcined powder, and then 1300 to 1650 ° in the air or oxygen atmosphere.
The method for producing a dielectric ceramic composition according to claim 1, wherein the firing is performed at C.