JPH06260021A - 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, nickel oxide, and manganese 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, or specific quantities of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, and praseodymium oxide are 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, many compositions are known, including barium titanate-bismuth system, barium titanate-niobium pentoxide-manganese dioxide system (JP-A-51-76597). Has been.

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 characteristic of the capacitor is evaluated by the signal voltage of 1 Vrms, a high signal electric field is applied as the dielectric layer becomes thinner, and the signal voltage characteristic of the conventional dielectric ceramic composition is poor. However, there is a problem in that the dielectric loss rapidly increases as the signal voltage increases, and the standard cannot 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,
0.8 to 1.5 parts by weight of niobium pentoxide, total amount of nickel oxide and manganese oxide are added to 100 parts by weight of barium titanate whose specific surface area is adjusted to 0.8 to 2.4 m ² / g by heat treatment. Is 0.1 part by weight or more, and the weight ratio of niobium pentoxide, nickel oxide, and manganese oxide is 3 ≦ niobium pentoxide / (nickel oxide + manganese oxide) (provided that 0 part by weight of nickel oxide and manganese oxide are used). 0 parts by weight are excluded). In addition, one or more of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, and praseosium oxide as an additive is added to the above composition in an amount of 0. 05
.About.0.50 parts by weight are added.

[0008]

According to the dielectric porcelain composition of the present invention, it is produced by the hydrothermal synthesis method, and its specific surface area is 0.8-2.
By using barium titanate with a very high purity and good crystallinity adjusted to 4 m ² / g, and by adding a specific amount of niobium pentoxide, nickel oxide and manganese oxide, it is possible to obtain a value of 2800 to about 4000. It is possible to obtain excellent characteristics with a high dielectric constant, a small change in the dielectric constant with temperature, and a small dielectric loss of 2.5% or less when a signal voltage of 50 Vrms / mm is applied. Then, by further adding a specific amount of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide or praseosium oxide to the above composition, the sinterability is improved without impairing the aforementioned properties. The effect of being able to do is obtained.

[0009]

【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, nickel oxide or manganese 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 its specific surface area is 0.4 to
Barium titanate adjusted to 2.6 m ² / g was used.
As a comparative example, barium titanate produced by the solid phase method and barium titanate produced by the oxalate method were used.
Then, with respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, and manganese oxide was converted into MnO ₂ , as shown in Table 1. The amount was weighed. In Table 1, niobium pentoxide, nickel oxide, and manganese oxide are simply represented as Nb, Ni, and Mn, respectively. These were mixed with pure water for 20 hours in a ball mill in which a zirconia cobblestone having a diameter of 5 mm was placed in a polyethylene container. After mixing, 9% by weight of a 5% PVA (polyvinyl alcohol) aqueous solution was added to the dried powder to granulate. Then, this granulated powder was put into a mold and molded into a disk shape having a diameter of 15 mm and a thickness of 0.5 mm at a pressure of 1 ton / cm ³ . The molded body thus obtained is baked at 1300 to 1400 ° C. for 2 hours, and silver electrodes are baked and applied to both surfaces of the baked body,
It was used as a sample for measurement. At the firing temperature of 1400 ° C. or lower, the sample whose sintered density did not reach 95% of the theoretical density was not sintered, and the following measurement of electrical characteristics was omitted. And
Capacitance and dielectric loss of sample at room temperature 1Vrms, 1KH
It was measured by z and the dielectric constant was calculated from the capacitance. On the other hand, the signal voltage characteristic of the dielectric loss is 50 Vrms /
mm was applied and measured. Moreover, the temperature characteristic of the dielectric constant is -6
It was measured at 1 Vrms and 1 KHz in the range of 0 to 135 ° C. The following (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.

[0011]

[Table 1]

[0012]

[Table 2]

As is clear from (Table 1) and (Table 2),
Addition of niobium pentoxide to 100 parts by weight of barium titanate
If the amount added is less than 0.8 parts by weight, the sinterability is poor, while
If it exceeds 1.5 parts by weight, the dielectric constant will decrease and nickel oxide
The total amount of aluminum and manganese oxide added is 0.1 parts by weight
If it is too small, the sinterability will be poor. In addition, niobium pentoxide / (nitric oxide
If the weight ratio of (Ackel + manganese oxide) is less than 3, it is dielectric.
The change of the rate with temperature is large. Furthermore, by hydrothermal synthesis method
The specific surface area of the generated barium titanate is 0.8 m ²/ G
If it is smaller, the dielectric loss increases, while on the other hand, 2.4m²/
If it is larger than g, the change in dielectric constant with respect to temperature is large. So
Then, barium titanate produced by the solid phase method and shu
When barium titanate produced by the acid salt method is used,
Compared to when using barium titanate produced by the synthetic method,
It is said that the electric charge does not increase or the dielectric loss is large.
There are drawbacks.

In this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 2) This embodiment corresponds to the invention described in claim 2, 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. This problem is solved by adding nickel and manganese oxide, and further adding lanthanum oxide.

First, a particle size of 0.1 produced by hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and lanthanum oxide was converted into La ₂ O _3.
The amounts shown in (Table 3) below were weighed in terms of conversion.
Also in (Table 3), niobium pentoxide, nickel oxide, manganese oxide, and lanthanum oxide are simply Nb, Ni, Mn, and L, respectively.
Expressed as a. A sample was prepared and evaluated by the same procedure as described below (Example 1).

1300 ° C. and 1330
The signal voltage characteristics of the sintered density at 13 ° C firing, the dielectric constant at room temperature at 1330 ° C, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 3) and (Table 4), the samples with # are comparative examples outside the scope of the present invention.

[0018]

[Table 3]

[0019]

[Table 4]

As is clear from (Table 3) and (Table 4), 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 0.50 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 this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 3) This embodiment also corresponds to the invention of claim 2, 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, The problem is solved by adding nickel oxide and manganese oxide, and further adding cerium oxide.

First, a particle size of 0.1 produced by the hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and cerium oxide was converted into CeO _2. The amounts shown in (Table 5) were weighed.
Also in (Table 5), niobium pentoxide, nickel oxide, manganese oxide, and cerium oxide are simply Nb, Ni, Mn, and C, respectively.
Expressed as e. A sample was prepared and evaluated by the same procedure as described below (Example 1).

See Table 6 below at 1300 ° C. and 1330
The signal voltage characteristics of the sintered density at 13 ° C firing, the dielectric constant at room temperature at 1330 ° C, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 5) and (Table 6), the samples with # are comparative examples outside the scope of the present invention.

[0025]

[Table 5]

[0026]

[Table 6]

As is clear from (Table 5) and (Table 6), 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 0.50 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 this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 4) This embodiment also corresponds to the invention described in claim 2, 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, The problem is solved by adding nickel oxide and manganese oxide, and further adding neodymium oxide.

First, the particle size of 0.1 produced by the hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and neodymium oxide was converted into Nd ₂ O.
_The amounts shown in the following (Table 7) in terms of ₃ were weighed. Also in (Table 7), niobium pentoxide, nickel oxide, manganese oxide, and neodymium oxide are simply Nb, Ni, and M, respectively.
Expressed as n and Nd. A sample was prepared and evaluated by the same procedure as described below (Example 1).

1300 ° C. and 1330 in the following (Table 8)
The signal voltage characteristics of the sintered density at 13 ° C firing, the dielectric constant at room temperature at 1330 ° C, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 7) and (Table 8), the samples with # are comparative examples outside the scope of the present invention.

[0032]

[Table 7]

[0033]

[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 neodymium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.50 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 this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 5) This embodiment also corresponds to the invention described in claim 2, 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, This problem is solved by adding nickel oxide and manganese oxide, and further adding samarium oxide.

First, the particle size of 0.1 produced by the hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and samarium oxide was converted into Sm ₂ O.
_The amounts shown in the following (Table 9) in terms of ₃ were weighed. In Table 9 as well, niobium pentoxide, nickel oxide, manganese oxide, and samarium oxide are simply used as Nb, Ni, and M, respectively.
Expressed as n and Sm. A sample was prepared and evaluated by the same procedure as described below (Example 1).

See Table 10 below at 1300 ° C. and 133
The signal voltage characteristics of the sintered density at 0 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 9) and (Table 10), the samples with # are comparative examples outside the scope of the present invention.

[0039]

[Table 9]

[0040]

[Table 10]

As is clear from (Table 9) and (Table 10),
The sinterability is improved by further adding 0.05 part by weight or more of samarium oxide to 100 parts by weight of barium titanate. However, when the addition amount exceeds 0.50 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 this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 6) This embodiment also corresponds to the invention described in claim 2, 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, The problem is solved by adding nickel oxide and manganese oxide, and further adding dysprosium oxide.

First, a particle size of 0.1 produced by the hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (part by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and dysprosium oxide was converted into D.
The amounts shown in (Table 11) below were weighed in terms of y ₂ O ₃ . (Table 11) also, niobium pentoxide, nickel oxide,
Manganese oxide and dysprosium oxide are simply N
It was represented by b, Ni, Mn, and Dy. A sample was prepared and evaluated by the same procedure as described below (Example 1).

See Table 12 below at 1300 ° C. and 133
The signal voltage characteristics of the sintered density at 0 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 11) and (Table 12), the samples with # are comparative examples outside the scope of the present invention.

[0046]

[Table 11]

[0047]

[Table 12]

As is clear from (Table 11) and (Table 12), 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, the addition amount is 0.5
When it exceeds 0 parts by weight, the dielectric constant is remarkably lowered, while 0.0
If the amount is less than 5 parts by weight, there is no effect of improving the sinterability, so it was excluded from the scope of the claims.

In this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 7) This embodiment also corresponds to the invention described in claim 2, 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, This problem is solved by adding nickel oxide and manganese oxide, and further adding ytterbium oxide.

First, a particle size of 0.1 produced by hydrothermal synthesis method
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and ytterbium oxide was converted into Y.
The amounts shown in the following (Table 13) in terms of b ₂ O ₃ were weighed. (Table 13) also shows niobium pentoxide, nickel oxide,
Manganese oxide and ytterbium oxide are simply N
It is represented by b, Ni, Mn, and Yb. A sample was prepared and evaluated by the same procedure as described below (Example 1).

See Table 14 below at 1300 ° C. and 133
The signal voltage characteristics of the sintered density at 0 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 13) and (Table 14), the samples with # are comparative examples outside the scope of the present invention.

[0053]

[Table 13]

[0054]

[Table 14]

As is clear from (Table 13) and (Table 14), 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, the addition amount is 0.5
When it exceeds 0 parts by weight, the dielectric constant is remarkably lowered, while 0.0
If the amount is less than 5 parts by weight, there is no effect of improving the sinterability, so it was excluded from the scope of the claims.

In this embodiment, manganese oxide is MnO ₂
However, other forms such as MnCO ₃ may be added, and the same effect can be obtained if the amount of manganese metal is the same.

(Embodiment 8) This embodiment also corresponds to the invention described in claim 2, 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, The problem is solved by adding nickel oxide and manganese oxide, and further adding praseosium oxide.

First, the particle size of 0.1 produced by hydrothermal synthesis method.
Fine barium titanate powder having a particle size of μm and a purity of 99.99% or more is calcined at 1050 ° C. and its specific surface area is 1.2 m ^2.
Barium titanate adjusted to / g was used. With respect to 100 g (parts by weight) of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ , nickel oxide was converted into NiO, manganese oxide was converted into MnO ₂ , and praseosium oxide was converted into P.
The amounts shown in (Table 15) below were weighed in terms of r ₂ O ₃ . (Table 15) also shows niobium pentoxide, nickel oxide,
Manganese oxide and praseosium oxide are simply N
It was expressed as b, Ni, Mn, and Pr. A sample was prepared and evaluated by the same procedure as described below (Example 1).

See Table 16 below for 1300 ° C. and 133
The signal voltage characteristics of the sintered density at 0 ° C. firing, the dielectric constant at 1330 ° C. at room temperature, the dielectric loss, and the dielectric loss are shown. In addition, in (Table 15) and (Table 16), the samples with # are comparative examples outside the scope of the present invention.

[0060]

[Table 15]

[0061]

[Table 16]

As is clear from (Table 15) and (Table 16), 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, the addition amount is 0.5
When it exceeds 0 parts by weight, the dielectric constant is remarkably lowered, while 0.0
If the amount is less than 5 parts by weight, there is no effect of improving the sinterability, so it was excluded from the scope of the claims.

In each of the above embodiments, 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.

In each of the above embodiments, manganese oxide is M
Although it was added as nO _2, it may be added in other forms such as MnCO _3, and the same effect can be obtained if the amount of metallic manganese is the same.

[0065]

The dielectric ceramic composition of the present invention is 2800.
It has excellent characteristics that the dielectric constant is high up to about 4000, the temperature change of the dielectric constant is small, and the dielectric loss is 2.5% or less when a signal voltage of 50 Vrms / mm is applied. 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 thinned, so that a small size and a large capacity can be easily realized.

Claims (2)

[Claims] 1. Niobium pentoxide 0.8 to 0.8 parts by weight with respect to 100 parts by weight of 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.
1.5 parts by weight, the total amount of nickel oxide and manganese oxide is 0.1 parts by weight or more, and the weight ratio of niobium pentoxide, nickel oxide and manganese oxide is 3 ≦ niobium pentoxide / (nickel oxide + manganese oxide). ) (Except 0 parts by weight of nickel oxide and 0 parts by weight of manganese oxide). 2. One or more of lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, ytterbium oxide, and praseosium oxide is added to 0.05 to 100 parts by weight of barium titanate as an additive. A dielectric ceramic composition obtained by adding 0.50 parts by weight.