JPH06260020A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition having a high dielectric constant, a small temperature change, a small dielectric loss, and a good signal voltage characteristic in a barium titanate dielectric material used for various ceramic capacitors. CONSTITUTION:Specific quantities of niobium pentaoxide, zinc oxide, and chromium oxide, or specific quantities of niobium pentaoxide, chromium oxide, and cobalt oxide, or specific quantities of niobium pentaoxide, magnesium oxide, and cobalt oxide are added to barium titanate generated by the hydrothermal synthesis method and adjusted with the specific surface area to 0.8-2.4m<2>/g by a heat treatment to obtain a composition. A specific quantity of silicon dioxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, or praseodymium oxide is added to the above composition to obtain a composition.

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 having a high dielectric constant, a small temperature change thereof, and a small dielectric loss.

[0002]

2. Description of the Related Art Conventionally, a dielectric ceramic composition containing barium titanate as a main component has been widely used as a material for a high dielectric constant type ceramic capacitor. Among them, materials whose dielectric constant changes little with temperature include barium titanate-bismuth type, barium titanate-niobium pentoxide-manganese dioxide type (JP-A-51-76597),
Many compositions are known.

Further, in order to meet the recent demand for smaller size and larger capacity of the monolithic ceramic capacitor, the dielectric constant of the dielectric material and the thinning of the dielectric layer are rapidly increasing. Therefore, it has a high dielectric constant and a small change in the dielectric constant with temperature,
In addition, the demand for dielectric materials with low dielectric loss is extremely high.

[0004]

However, most of the above-mentioned conventional dielectric ceramic compositions use barium titanate obtained by solid phase reaction from barium carbonate and titanium oxide as a raw material. The dielectric constant is 3000 or less.

Further, in general, in a ferroelectric substance such as barium titanate, when the applied electric field strength increases, the change in the dielectric constant increases and the dielectric loss also increases. Since the characteristics of the capacitor are evaluated at a signal voltage of 1 Vrms, a high signal electric field is applied as the dielectric layer becomes thinner, and the above-mentioned conventional dielectric ceramic composition has poor signal voltage characteristics, resulting in poor signal Dielectric loss increases sharply with increasing voltage,
There was a problem that the standard could not be satisfied.

The present invention solves the above-mentioned conventional problems, and provides a dielectric ceramic composition having a high dielectric constant, a small temperature change, a small dielectric loss, and a good signal voltage characteristic. To aim.

[0007]

In order to achieve this object, the dielectric ceramic composition of the present invention is produced by a hydrothermal synthesis method,
It is formed by adding a specific amount of niobium pentoxide, zinc oxide, or cobalt oxide to barium titanate whose specific surface area is adjusted to 0.8 to 2.4 m ² / g by heat treatment. Further, in the above barium titanate, a specific amount of niobium pentoxide,
Chromium oxide and cobalt oxide are added.
Further, a specific amount of niobium pentoxide, magnesium oxide, or cobalt oxide is added to the barium titanate. Alternatively, it proposes a composition obtained by further adding a specific amount of silicon dioxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, or praseosium oxide to these compositions.

[0008]

The dielectric ceramic composition of the present invention is produced by a hydrothermal synthesis method, and its specific surface area is 0.8 to 2.4 m by heat treatment.
Using barium titanate having a very high purity and good crystallinity adjusted to ² / g, a specific amount of niobium pentoxide, zinc oxide and cobalt oxide, or a specific amount of niobium pentoxide, chromium oxide and oxide was used. Since cobalt, or niobium pentoxide, magnesium oxide, and cobalt oxide are added, with a high dielectric constant of 2700 to about 4000,
It is possible to obtain excellent characteristics in which the change in dielectric constant with temperature is small and the dielectric loss when a signal voltage of 50 Vrms / mm is applied is as small as 2.5% or less.

Further, by adding a specific amount of silicon dioxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytribium oxide or praseosium oxide to the above composition, the above-mentioned characteristics are not impaired. It becomes possible to improve the sinterability.

[0010]

【Example】

Example 1 An example of the present invention will be described below.
This example corresponds to the invention described in claim 1, in which a specific amount of niobium pentoxide, zinc oxide, or cobalt oxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. The problem is solved by.

Particle size 0.1 μm produced by hydrothermal synthesis method,
90 barium titanate fine powder with a purity of 99.99% or more
The powder is calcined at 0 to 1150 ° C. and has a specific surface area of 0.4 to 2.
6m ²Barium titanate adjusted to / g was used. Comparison
As an example, barium titanate produced by the solid phase method, and
Barium titanate produced by the oxalate method was used. the above
Niobium pentoxide is added to 100 g of barium titanate.
Nb₂O_FiveConverted zinc oxide to ZnO and converted to cobalt oxide
To Co₃O_FourThe amounts shown in conversion (Table 1) were weighed.
The cobalt oxide used had a purity of metallic cobalt.
Of 73 to 74% was used. In Table 1, dipentoxide
Ofobium, zinc oxide, and cobalt oxide are simply Nb and Z, respectively.
Expressed as n and Co. Place these directly in a polyethylene container.
With a ball mill containing zirconia boulders with a diameter of 5 mm,
Mixed with pure water for 20 hours. After mixing, dry the slurry.
5% PVA (polyvinyl alcohol) water soluble in dried powder
The liquid was added to 9% by weight and granulated. Put the granulated powder in the mold and
1 ton / cm in the shape of a disk with a diameter of 15 mm and a thickness of 0.5 mm³At the pressure of
Molded. The obtained molded body is 2 at 1300 to 1400 ° C.
Samples for measurement after baking for a time, baking and applying a silver electrode
And In addition, at a firing temperature of 1400 ° C. or less, the sintered density is
Samples that do not reach 95% of the theoretical density are not sintered and
The measurement of the electrical characteristics of is omitted. Capacitance of sample at room temperature
And dielectric loss are measured at 1 Vrms and 1 kHz, and
The dielectric constant was calculated. The signal characteristic of the dielectric loss is the signal of 1 kHz
It was measured by applying 50 Vrms / mm. Also, the temperature of the dielectric constant
Characteristic in the range of -60 to 135 ℃ at 1Vrms, 1kHz
It was measured.

Table 2 shows the dielectric constant at room temperature, the dielectric loss, the signal voltage characteristics of the dielectric loss and the dielectric constant at 20 ° C. at each temperature (-55 ° C., -25 ° C., 85 ° C., 125 ° C.). The rate of change is shown. In addition, in (Table 1) and (Table 2), the samples with # are comparative examples outside the scope of the present invention.

[0013]

[Table 1]

[0014]

[Table 2]

As is clear from (Table 1) and (Table 2), if the amount of niobium pentoxide added is less than 0.7 parts by weight based on 100 parts by weight of barium titanate, the sinterability is poor, while 2.2 parts by weight. When it exceeds the range, the dielectric constant becomes low. Further, if the weight ratio of niobium pentoxide / (zinc oxide + cobalt oxide) is less than 3, the change in dielectric constant with temperature is large.
If it is larger, the sinterability is poor. Further, when the specific surface area of barium titanate produced by the hydrothermal synthesis method is smaller than 0.8 m ² / g, the dielectric loss becomes large, while when it is larger than 2.4 m ² / g, the change of the dielectric constant with temperature becomes large. In addition, when barium titanate produced by the solid phase method and barium titanate produced by the oxalate method are used, the permittivity does not become larger than when barium titanate produced by the hydrothermal synthesis method is used, or There is a drawback that the dielectric loss is large.

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

(Embodiment 2) This embodiment corresponds to the invention described in claim 4, in which barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment is mixed with a specific amount of niobium pentoxide and an oxide. By adding chromium and cobalt oxide,
It is a solution to the problem.

Particle size 0.1 μm produced by hydrothermal synthesis method,
90 barium titanate fine powder with a purity of 99.99% or more
The powder is calcined at 0 to 1150 ° C. and has a specific surface area of 0.4 to 2.
6m ²Barium titanate adjusted to / g was used. Comparison
As an example, barium titanate produced by the solid phase method, and
Barium titanate produced by the oxalate method was used. (table
As shown in 3), 100 g of the above barium titanate
In contrast, niobium pentoxide is added to Nb₂O_FiveConverted to chromium oxide
Cr₂O₃Converted to cobalt oxide as Co₃O_FourIn conversion (table
The amount shown in 3) was weighed. The cobalt oxide used
Is a metallic cobalt with a purity of 73-74%
I was there. (Table 3) also, niobium pentoxide, chromium oxide, co-oxide
The balts are simply expressed as Nb, Cr and Co, respectively. Less than
The sample is prepared and evaluated by the same procedure as in (Example 1).
It was. Again, at a firing temperature below 1400 ° C, the sintered density
Samples that do not reach 95% of theoretical density are not sintered and
The measurement of characteristics was omitted.

Table 4 shows the dielectric constant at room temperature, the dielectric loss, the signal voltage characteristics of the dielectric loss, and the respective temperatures (-55 ° C, -25 ° C, 85 ° C, 125 ° C) with respect to the dielectric constant at 20 ° C. The change rate of is shown. In addition, in (Table 3) and (Table 4), the samples with # are comparative examples outside the scope of the present invention.

[0020]

[Table 3]

[0021]

[Table 4]

As is clear from (Table 3) and (Table 4), if the amount of niobium pentoxide added is less than 0.8 parts by weight relative to 100 parts by weight of barium titanate, the sinterability is poor, while that of 2.0 parts by weight. If it exceeds 0.5 parts by weight, the dielectric constant becomes low, and if the total amount of chromium oxide and cobalt oxide added is less than 0.15 parts by weight, the sinterability is poor. If the weight ratio of niobium pentoxide / (chromium oxide + cobalt oxide) is less than 3, the change in dielectric constant with temperature is large. Further, when the specific surface area of barium titanate produced by the hydrothermal synthesis method is smaller than 0.8 m ² / g, the dielectric loss becomes large, and when it is larger than 2.4 m ² / g, the change of the dielectric constant with respect to temperature becomes large. In addition, when barium titanate produced by the solid phase method and barium titanate produced by the oxalate method are used, the permittivity does not become larger than when barium titanate produced by the hydrothermal synthesis method is used, or There is a drawback that the dielectric loss is large.

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

(Embodiment 3) This embodiment corresponds to the invention described in claim 7, wherein barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment is mixed with a specific amount of niobium pentoxide and an oxide. The problem is solved by adding magnesium and cobalt oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
90 barium titanate fine powder with a purity of 99.99% or more
The powder is calcined at 0 to 1150 ° C. and has a specific surface area of 0.4 to 2.
6m ²Barium titanate adjusted to / g was used. Comparison
As an example, barium titanate produced by the solid phase method, and
Barium titanate produced by the oxalate method was used. (table
As shown in 5), 100 g of the above barium titanate
In contrast, niobium pentoxide is added to Nb₂O_FiveIn terms of conversion, magnetic oxide
Cobalt oxide is converted into Co₃O_FourIn conversion
The amounts shown in (Table 5) were weighed. In addition, the used oxide
Lut has a purity of 73 to 74% as metallic cobalt.
Was used. (Table 5) Even niobium pentoxide and magnesium oxide
And cobalt oxide are simply referred to as Nb, Mg, and Co, respectively.
did. A sample was prepared by the same procedure as described below (Example 1).
It was made and evaluated. Here too the firing temperature below 1400 ° C
Sinter the sample whose sintered density does not reach 95% of the theoretical density.
The measurement of electrical characteristics was omitted.

Table 6 shows the dielectric constant at room temperature, the dielectric loss, the signal voltage characteristics of the dielectric loss, and the respective temperatures (-55 ° C, -25 ° C, 85 ° C, 125 ° C) with respect to the dielectric constant at 20 ° C. The change rate of is shown. In addition, in (Table 5) and (Table 6), the samples with # are comparative examples outside the scope of the present invention.

[0027]

[Table 5]

[0028]

[Table 6]

As is clear from (Table 5) and (Table 6), if the amount of niobium pentoxide added to 100 parts by weight of barium titanate is less than 1.0 part by weight, the sinterability will be poor, while 2.0 parts by weight will be obtained. When it exceeds the range, the dielectric constant becomes low. Further, if the weight ratio of niobium pentoxide / (magnesium oxide + cobalt oxide) is less than 3, the change in dielectric constant with respect to temperature is large, while if it is more than 10, the sinterability is poor. Moreover, the specific surface area of barium titanate produced by the hydrothermal synthesis method is 0.8 m.
If it is smaller than ² / g, the dielectric loss becomes large, while 2.4
If it is larger than m ² / g, the change in dielectric constant with respect to temperature is large. In addition, when barium titanate produced by the solid phase method and barium titanate produced by the oxalate method are used, the permittivity does not become larger than when barium titanate produced by the hydrothermal synthesis method is used, or There is a drawback that the dielectric loss is large.

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

(Embodiment 4) This embodiment corresponds to the inventions described in claims 2, 5 and 8, in which barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment has a specific amount of 5 parts. This problem is solved by adding niobium oxide, zinc oxide, chromium oxide, magnesium oxide, and cobalt oxide, and further adding silicon dioxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Zinc oxide is converted to ZnO, chromium oxide is converted to Cr ₂ O ₃ , magnesium oxide is converted to MgO, cobalt oxide is converted to Co ₃ O ₄ , and silicon dioxide is converted to SiO _{2 in} the amounts shown in (Table 7). Weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Also in (Table 7), niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide, and silicon dioxide are simply represented as Nb, Zn, Cr, Mg, Co, and Si, respectively. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 8 shows the signal density characteristics of the sintered density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. firing at room temperature, the dielectric loss, and the dielectric loss. still,
In Tables 7 and 8, the samples with # are comparative examples outside the scope of the present invention.

[0035]

[Table 7]

[0036]

[Table 8]

As is clear from (Table 7) and (Table 8), the sinterability is improved by further adding 0.05 part by weight or more of silicon dioxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.3 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 5) This embodiment corresponds to the inventions described in claims 3, 6 and 9, wherein barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment has a specific amount of 5 This problem is solved by adding niobium oxide, zinc oxide, chromium oxide, magnesium oxide, and cobalt oxide, and further adding lanthanum oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Table 9 shows zinc oxide in terms of ZnO, chromium oxide in terms of Cr ₂ O ₃ , magnesium oxide in terms of MgO, cobalt oxide in terms of Co ₃ O ₄ , and lanthanum oxide in terms of La ₂ O ₃ . The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Also in Table 9, niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide, and lanthanum oxide are simply represented as Nb, Zn, Cr, Mg, Co, and La, respectively. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 10 shows signal voltage characteristics of sintering density at 1300 ° C. and 1330 ° C. firing, dielectric constant at room temperature at 1330 ° C. firing, dielectric loss, and dielectric loss.
In addition, in (Table 9) and (Table 10), the samples with # are comparative examples outside the scope of the present invention.

[0042]

[Table 9]

[0043]

[Table 10]

As is clear from (Table 9) and (Table 10),
The sinterability is improved by further adding 0.05 parts by weight or more of lanthanum oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 6) The present embodiment is the same as claim 3.
Corresponding to the inventions of 6 and 9, a specific amount of niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. However, the problem is solved by further adding cerium oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Zinc oxide is converted to ZnO, chromium oxide is converted to Cr ₂ O ₃ , magnesium oxide is converted to MgO, cobalt oxide is converted to Co ₃ O ₄ , and cerium oxide is converted to CeO ₂ (Table 1
The amount shown in 1) was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Also in (Table 11), niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide, and cerium oxide are simply represented as Nb, Zn, Cr, Mg, Co, and Ce, respectively. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 12 shows the signal voltage characteristics of the sintering density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss.
In addition, in (Table 11) and (Table 12), the samples with # are comparative examples outside the scope of the present invention.

[0049]

[Table 11]

[0050]

[Table 12]

As is clear from (Table 11) and (Table 12), the sinterability is improved by further adding 0.05 part by weight or more of cerium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 7) The present embodiment is the same as claim 3.
Corresponding to the inventions of 6 and 9, a specific amount of niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. However, the problem is solved by further adding neodymium oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Table 13 shows zinc oxide in terms of ZnO, chromium oxide in terms of Cr ₂ O ₃ , magnesium oxide in terms of MgO, cobalt oxide in terms of Co ₃ O ₄ , and neodymium oxide in terms of Nd ₂ O ₃ . The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Also in Table 13, niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide and neodymium oxide are simply Nb, Zn, Cr, Mg, Co and N, respectively.
Expressed as d. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 14 shows the signal voltage characteristics of the sintering density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. firing at room temperature, the dielectric loss, and the dielectric loss.
In addition, in (Table 13) and (Table 14), the samples with # are comparative examples outside the scope of the present invention.

[0056]

[Table 13]

[0057]

[Table 14]

As is clear from (Table 13) and (Table 14), by adding more than 0.05 part by weight of neodymium oxide to 100 parts by weight of barium titanate,
Sinterability is improved. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 8) The present embodiment is the same as claim 3.
Corresponding to the inventions of 6 and 9, a specific amount of niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. However, the problem is solved by further adding samarium oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Table 15 shows zinc oxide in terms of ZnO, chromium oxide in terms of Cr ₂ O ₃ , magnesium oxide in terms of MgO, cobalt oxide in terms of Co ₃ O ₄ , and samarium oxide in terms of Sm ₂ O ₃ . The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. In Table 15 as well, niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide, and samarium oxide are simply Nb, Zn, Cr, Mg, Co, and S, respectively.
Expressed as m. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 16 shows the signal voltage characteristics of the sintered density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss.
In addition, in (Table 15) and (Table 16), the samples with # are comparative examples outside the scope of the present invention.

[0063]

[Table 15]

[0064]

[Table 16]

As is clear from (Table 15) and (Table 16), by further adding 0.05 parts by weight or more of samarium oxide to 100 parts by weight of barium titanate,
Sinterability is improved. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 9) The present embodiment is the same as claim 3.
Corresponding to the inventions of 6 and 9, a specific amount of niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, cobalt oxide is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. However, the problem was solved by further adding dysprosium oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Zinc oxide is converted into ZnO, chromium oxide is converted into Cr ₂ O ₃ , magnesium oxide is converted into MgO, cobalt oxide is converted into Co ₃ O ₄ , and dysprosium oxide is converted into Dy ₂ O ₃ (Table 17). The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. (Table 17) also shows niobium pentoxide, zinc oxide,
Chromium oxide, magnesium oxide, cobalt oxide, dysprosium oxide are simply Nb, Zn, Cr, Mg, respectively.
Expressed as Co and Dy. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

(Table 18) shows the signal voltage characteristics of the sintered density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss.
In addition, in (Table 17) and (Table 18), the samples with # are comparative examples outside the scope of the present invention.

[0070]

[Table 17]

[0071]

[Table 18]

As is apparent from (Table 17) and (Table 18), the sinterability is improved by further adding 0.05 parts by weight or more of dysprosium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 10) This embodiment also corresponds to the invention described in claims 3, 6 and 9, and a specific amount of barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment is used. The problem is solved by adding niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, and cobalt oxide, and further by adding ytterbium oxide.

Particle size 0.1 μm produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Zinc oxide is shown in terms of ZnO, chromium oxide in terms of Cr ₂ O ₃ , magnesium oxide in terms of MgO, cobalt oxide in terms of Co ₃ O ₄ , and ytterbium oxide in terms of Yb ₂ O ₃ (Table 19). The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. (Table 19) also shows niobium pentoxide, zinc oxide,
Chromium oxide, magnesium oxide, cobalt oxide and ytterbium oxide are simply Nb, Zn, Cr, Mg, respectively.
Expressed as Co and Yb. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

(Table 20) shows the signal voltage characteristics of the sintering density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss.
In addition, in Tables 19 and 20, the samples with # are comparative examples outside the scope of the present invention.

[0077]

[Table 19]

[0078]

[Table 20]

As is clear from (Table 19) and (Table 20), the sinterability is improved by further adding 0.05 parts by weight or more of ytterbium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

(Embodiment 11) This embodiment also corresponds to the inventions described in claims 3, 6 and 9, in which barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment has a specific amount of The problem is solved by adding niobium pentoxide, zinc oxide, chromium oxide, magnesium oxide, and cobalt oxide, and further adding praseosium oxide.

Particle size 0.1 μm, produced by hydrothermal synthesis method,
10 barium titanate fine powder with a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and whose specific surface area was adjusted to 1.2 m ² / g was used. With respect to 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Table 21 shows zinc oxide in terms of ZnO, chromium oxide in terms of Cr ₂ O ₃ , magnesium oxide in terms of MgO, cobalt oxide in terms of Co ₃ O ₄ , and praseodymium oxide in terms of Pr ₂ O ₃ . The amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. (Table 21) also shows niobium pentoxide, zinc oxide,
Chromium oxide, magnesium oxide, cobalt oxide, and praseosium oxide are simply Nb, Zn, Cr, Mg, respectively.
Expressed as Co and Pr. A sample was prepared and evaluated by the same procedure as described below (Example 1).

In this embodiment, cobalt oxide is Co ₃ O ₄
However, other forms such as CoO may be added, and the same effect can be obtained if the amount of metallic cobalt is the same.

Table 22 shows the signal voltage characteristics of the sintering density at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature when firing at 1330 ° C., the dielectric loss, and the dielectric loss.
In addition, in (Table 21) and (Table 22), the samples with # are comparative examples outside the scope of the present invention.

[0084]

[Table 21]

[0085]

[Table 22]

As is clear from (Table 21) and (Table 22), the sinterability is improved by further adding 0.05 parts by weight or more of praseosium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.5 parts by weight, the dielectric constant is remarkably lowered, and when the addition amount is less than 0.05 parts by weight, there is no effect of improving the sinterability, and therefore it is excluded from the scope of the claims.

In each of the above examples, the additive is
Lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide,
The case where one of praseosium oxide is added in an amount of 0.05 to 0.50 parts by weight with respect to 100 parts by weight of barium titanate has been described, but even if two or more of these additives are added at the same time, The total addition amount is 0.05 ~
Within the range of 0.50 parts by weight, it is possible to obtain the same effects as those of the above-mentioned respective examples.

[0088]

The dielectric porcelain composition of the present invention is produced by a hydrothermal synthesis method, and by heat treatment, by using barium titanate having high purity and good crystallinity whose specific surface area is appropriately adjusted, The dielectric constant is as high as 2700 to 4000, the change in the dielectric constant with temperature is small, and the dielectric loss when applying a signal voltage of 50 Vrms / mm is 2.5% or less, which is excellent characteristics. Also, silicon dioxide, lanthanum oxide,
Sinterability can be improved by adding a specific amount of cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, or praseosium oxide.

Therefore, it can be put to practical use as a dielectric material for a ceramic capacitor, and particularly in a laminated ceramic capacitor, the dielectric layer can be made thin, so that it is possible to easily realize a small size and a large capacity. Is.

Claims (9)

[Claims] 1. Barium titanate, niobium pentoxide, zinc oxide, which is produced by a hydrothermal synthesis method and whose specific surface area is adjusted to 0.8 to 2.4 m ² / g by heat treatment, is used. Barium titanate made of cobalt oxide 10
0.7 to 2.2 parts by weight of niobium pentoxide with respect to 0 parts by weight, and the weight ratio of niobium pentoxide, zinc oxide and cobalt oxide is 3 ≦ niobium pentoxide / (zinc oxide + cobalt oxide). ≤8 (however, 0 parts by weight of zinc oxide, 0 of cobalt oxide
(Excluding parts by weight). 2. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.30 parts by weight of silicon dioxide is further added to 100 parts by weight of barium titanate. 3. One or more of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, and praseosium oxide are added to 100 parts by weight of barium titanate in an amount of 0.
The dielectric ceramic composition according to claim 1, wherein the dielectric ceramic composition is added in an amount of 05 to 0.50 parts by weight. 4. Barium titanate, niobium pentoxide, chromium oxide, which is produced by hydrothermal synthesis and whose specific surface area is adjusted to 0.8 to 2.4 m ² / g by heat treatment, is used. Made of cobalt oxide, barium titanate 1
0.8 to 2.0 parts by weight of niobium pentoxide, 0.15 parts by weight or more in total of chromium oxide and cobalt oxide, and the weight of niobium pentoxide, chromium oxide, and cobalt oxide with respect to 00 parts by weight. A dielectric ceramic composition having a ratio of 3 ≦ niobium pentoxide / (chromium oxide + cobalt oxide) (excluding 0 part by weight of chromium oxide and 0 part by weight of cobalt oxide). 5. The dielectric ceramic composition according to claim 4, wherein 0.05 to 0.30 parts by weight of silicon dioxide is further added to 100 parts by weight of barium titanate. 6. One or more of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide and praseosium oxide are added to 100 parts by weight of barium titanate in an amount of 0.
The dielectric ceramic composition according to claim 4, wherein the dielectric ceramic composition is added in an amount of 05 to 0.50 parts by weight. 7. Barium titanate, niobium pentoxide, magnesium oxide, using barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted to 0.8 to 2.4 m ² / g by heat treatment, It is made of cobalt oxide, and niobium pentoxide is 1.0 to 2. per 100 parts by weight of barium titanate.
0 parts by weight, and niobium pentoxide, magnesium oxide,
A dielectric ceramic composition in which the weight ratio of cobalt oxide is 3 ≦ niobium pentoxide / (magnesium oxide + cobalt oxide) ≦ 10 (except 0 parts by weight of magnesium oxide and 0 parts by weight of cobalt oxide). 8. The dielectric ceramic composition according to claim 7, wherein 0.05 to 0.30 parts by weight of silicon dioxide is further added to 100 parts by weight of barium titanate. 9. One or more of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, and praseosium oxide are added to 100 parts by weight of barium titanate in an amount of 0.
The dielectric ceramic composition according to claim 7, wherein the dielectric ceramic composition is added in an amount of 05 to 0.50 parts by weight.