JPH07220525A - Dielectric ceramic composition - Google Patents

Abstract

PURPOSE:To provide a dielectric ceramic composition with high dielectric constant, low temperature variation, and low dielectric loss. CONSTITUTION:0.8-1.5 pts.wt. niobium pentoxide and 0.3-2.0 pts.wt. zinc oxide are added to 100 pts.wt. barium titanate whose specific surface area is adjusted to 0.7-2.7m<2>/g. In addition, 0.02-0.3 pts.wt. at least one of strontium oxide and silica is added to the above mixture.

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 used for, for example, a laminated ceramic capacitor.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor or the like uses a dielectric ceramic composition having a high dielectric constant in order to increase its capacity. Conventionally, as the dielectric composition, barium titanate is used as a main component, A composition to which bismuth oxide or niobium pentoxide is added is known. A dielectric ceramic composition having such a high dielectric constant has been used to develop a multilayer ceramic capacitor, etc., in which the number of laminated layers is increased by thinning the dielectric.

[0003]

When the dielectric constant of the above dielectric ceramic composition is increased, the rate of temperature change increases and the dielectric loss also increases. Therefore, there is a limit to increase the dielectric constant, and there is a problem that it is not possible to provide a small-sized and large-capacity monolithic ceramic capacitor having a thin dielectric layer.

An object of the present invention is to provide a dielectric porcelain composition having a high dielectric constant and a small temperature change and dielectric loss.

[0005]

In order to achieve this object, the dielectric ceramic composition of the present invention has a specific surface area of 0.7 to
0.8 to 1.5 parts by weight of niobium oxide and 0.3 to 2.0 parts by weight of zinc oxide were added to 100 parts by weight of barium titanate adjusted to 2.7 m ² / g, and further strontium oxide and dioxide were added. Of silicon, at least one type is 0.
The amount added is from 02 to 0.3 parts by weight.

[0006]

FUNCTION This dielectric ceramic composition has a dielectric constant of 2500-4.
000, the temperature change and the dielectric loss are small, and X7
It satisfies the R characteristics (capacity change rate within ± 10% at −25 to 85 ° C.).

As a result, by using this dielectric ceramic composition, a small-sized and large-capacity monolithic ceramic capacitor can be obtained.

[0008]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat treated and wet pulverized to have a specific surface area of 0.7 to
It was adjusted to 2.7 m ² / g. The composition after firing niobium pentoxide, zinc oxide, silicon dioxide, and strontium carbonate based on 100 g (part by weight) of barium titanate (particle size 0.5 μm) thus obtained is shown in (Table 1). Weighed so that

[0010]

[Table 1]

Thereafter, these are placed in a polyethylene container together with zirconia cobblestone having a diameter of 5 mm, pure water is added, and
Wet mixed for 0 hours. Next, this mixed slurry was dried with a stainless steel pad, and 10 parts by weight of a 5% polyvinyl alcohol aqueous solution was added to the dried powder to granulate. Then, at a pressure of 1 ton / cm ³ , a diameter of 15 mm and a thickness of 0.
A 5 mm disk shape was formed and fired at 1300 to 1400 ° C. for 2 hours, and silver electrodes were baked and applied on both upper and lower surfaces of this sintered body to prepare a sample. Next, the results of measuring the electrical characteristics of the sample under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C. (Table 2)
Shown in.

[0012]

[Table 2]

Those marked with * in (Table 1) and (Table 2) are comparative examples outside the claims of the present invention. Nb, Zn, Si, and Sr are niobium pentoxide,
Indicates zinc oxide, silicon dioxide and strontium oxide.
According to (Table 2), barium titanate and niobium pentoxide,
Of zinc oxide, strontium oxide and silicon dioxide,
It can be seen that by adding at least one kind, the dielectric constant is high and the dielectric loss and the temperature change of the dielectric constant are small. However, if zinc oxide is less than 0.3 g (parts by weight), it will not sinter or the temperature change rate will be large, and if it is more than 2.0 g (part by weight), the temperature change rate will be large. If strontium oxide is not added with silicon dioxide, the effect is less than 0.02 g (parts by weight),
If it is more than 0.3 g (parts by weight), the dielectric constant will be significantly reduced. Silicon oxide has no effect if less than 0.02 g (parts by weight) without adding strontium oxide.
If it is more than g (parts by weight), the dielectric loss becomes significantly worse.

(Second Embodiment) A second embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat treated and wet pulverized to have a specific surface area of 0.7 to
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, manganese carbonate, silicon dioxide, and strontium carbonate (Table 3 ) Weighed so as to become as shown in FIG.

[0016]

[Table 3]

A sample was prepared in the same manner as in Example 1, and the electrical characteristics of the sample were measured under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C. (Table 4).

[0018]

[Table 4]

Those marked with * in (Table 3) and (Table 4) are comparative examples outside the claims of the present invention. Nb, Zn, Mn, Si, and Sr represent niobium pentoxide, zinc oxide, manganese oxide, silicon dioxide, and strontium oxide, respectively. Table 4 shows that the addition of manganese oxide improves the sinterability. However, if the addition amount is less than 0.03, there is no effect, and if it is more than 0.3, the sinterability decreases.

(Embodiment 3) A third embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat treated and wet pulverized to have a specific surface area of 0.7-.
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size: 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and lanthanum oxide was (Table 1 5) Weighed as shown in FIG.

[0022]

[Table 5]

Samples were prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C. (Table 6).

[0024]

[Table 6]

Those marked with * in (Table 5) and (Table 6) are comparative examples outside the claims of the present invention. Nb, Zn, Si, Sr, and La are niobium pentoxide, zinc oxide, silicon dioxide, strontium oxide, and
Indicates lanthanum oxide. According to (Table 6), the addition of lanthanum oxide has the effect of improving the sinterability. However, if the addition amount is 0.05 g (parts by weight), there is no effect, and if it is more than 0.50 g (parts by weight), the dielectric constant is significantly reduced.

(Embodiment 4) A fourth embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat-treated and wet pulverized to have a specific surface area of 0.7-.
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and cerium oxide was (Table Weighed as shown in 7).

[0028]

[Table 7]

A sample was prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of a frequency of 1 kHz and room temperature of 20 ° C. (Table 8).

[0030]

[Table 8]

Those marked with * in (Table 7) and (Table 8) are comparative examples outside the claims of the present invention. Nb, Zn, Si, Sr, and Ce are niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and
Indicates cerium oxide. According to Table 8, the addition of cerium oxide has the effect of improving the sinterability. However, if the addition amount is 0.05 g (parts by weight), there is no effect, and if it is more than 0.50 g (parts by weight), the dielectric constant is significantly reduced.

(Fifth Embodiment) The fifth embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat-treated and wet pulverized to have a specific surface area of 0.7 to 0.7.
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size: 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and neodymium oxide (Table Weighed as shown in 9).

[0034]

[Table 9]

A sample was prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C., and the results are shown in Table 10.

[0036]

[Table 10]

Those marked with * in (Table 9) and (Table 10) are comparative examples outside the claims of the present invention. Nb, Zn, Si, Sr, and Nd are niobium pentoxide, zinc oxide, silicon dioxide, strontium oxide, and
Indicates neodymium oxide. According to (Table 10), the addition of neodymium oxide has the effect of improving the sinterability. However, if the addition amount is 0.05 g (parts by weight), there is no effect, and if it is more than 0.50 g (parts by weight), the dielectric constant is significantly reduced.

(Embodiment 6) A sixth embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat treated and wet pulverized to have a specific surface area of 0.7 to
It was adjusted to 2.7 m ² / g. The composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and samarium oxide was calculated based on 100 g (part by weight) of barium titanate (particle size 0.5 μm) thus obtained. Weighed as shown in 11).

[0040]

[Table 11]

Samples were prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of frequency 1 kHz and room temperature 20 ° C. (Table 12).

[0042]

[Table 12]

Those marked with * in (Table 11) and (Table 12) are comparative examples outside the claims of the present invention.
Nb, Zn, Si, Sr, and Sm represent niobium pentoxide, zinc oxide, silicon dioxide, strontium oxide, and samarium oxide, respectively. According to (Table 12), the addition of samarium oxide has the effect of improving the sinterability. However, if the addition amount is 0.05 g (parts by weight), there is no effect, and if it is more than 0.50 g (parts by weight), the dielectric constant is significantly reduced.

(Seventh Embodiment) A seventh embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat-treated and wet pulverized to have a specific surface area of 0.7-.
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and dysprosium oxide was (Table Weighed as shown in 13).

[0046]

[Table 13]

A sample was prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C., and the results are shown in Table 14.

[0048]

[Table 14]

Those marked with * in (Table 13) and (Table 14) are comparative examples outside the claims of the present invention.
Nb, Zn, Si, Sr, and Dy represent niobium pentoxide, zinc oxide, silicon dioxide, strontium oxide, and dysprosium oxide, respectively. According to (Table 14),
The addition of dysprosium oxide has the effect of improving the sinterability. However, the addition amount is 0.05g
If it is more than 0.50 g (part by weight), the permittivity is greatly reduced.

(Embodiment 8) An eighth embodiment of the present invention will be described below.

First, barium titanate produced by the hydrothermal synthesis method is heat treated and wet pulverized to have a specific surface area of 0.7 to
It was adjusted to 2.7 m ² / g. With respect to 100 g (part by weight) of barium titanate (particle size: 0.5 μm) thus obtained, the composition after firing niobium pentoxide, zinc oxide, silicon dioxide, strontium carbonate, and ytterbium oxide was Weighed as shown in 15).

[0052]

[Table 15]

Samples were prepared in the same manner as in Example 1, and the electrical characteristics were measured under the conditions of a frequency of 1 kHz and a room temperature of 20 ° C. (Table 16).

[0054]

[Table 16]

Those marked with * in (Table 15) and (Table 16) are comparative examples outside the claims of the present invention.
Further, Nb, Zn, Si, Sr, and Yb represent niobium pentoxide, zinc oxide, silicon dioxide, strontium oxide, and ytterbium oxide, respectively. According to (Table 16),
The addition of ytterbium oxide has the effect of improving the sinterability. However, the addition amount is 0.05g
If it is more than 0.50 g (part by weight), the permittivity is greatly reduced.

The examples shown in (Example 1) to (Example 8) are examples, and the specific surface area is 0.7 to 2.7.
For 100 g (weight part) of barium titanate of m ² / g, 0.8-1.5 g (weight part) of niobium pentoxide, 0.3-2.0 g (weight part) of zinc oxide, strontium oxide and dioxide At least one type of silicon is 0.02 to 0.
It may be added in the range of 3 g (part by weight). Further, if one kind of manganese oxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, and ytterbium oxide is added, the manganese oxide content is 100 g (part by weight) of manganese oxide.
03-0.3g (parts by weight), other items are 0.05-
It may be added in the range of 0.5 g (part by weight).

The specific surface area of barium titanate is 0.7 m ² /
When it is smaller than g, the dielectric loss becomes large and 2.7 m ² /
If it exceeds g, the permittivity decreases and it becomes difficult to handle because it becomes aggregated powder.

For this reason, the claims of the present invention have been determined. Although barium titanate was produced by the hydrothermal synthesis method, it may be produced by another synthesis method as long as it has good characteristics.

[0059]

As described above, the dielectric ceramic composition of the present invention has a high dielectric constant of 2500 to 4000, a small temperature change and a small dielectric loss, and has an X7R characteristic (−25 to 85 ° C.).
The rate of change in capacity is within ± 10%). As a result, by using this dielectric ceramic composition, the dielectric layer can be made thin, and a small-sized and large-capacity monolithic ceramic capacitor can be obtained.

Claims (8)

[Claims] 1. To 100 parts by weight of barium titanate whose specific surface area is adjusted to 0.7 to 2.7 m ² / g, 0.8 to 1.5 parts by weight of niobium pentoxide and 0.3 to 0.3 parts of zinc oxide are claimed. A dielectric ceramic composition containing 2.0 parts by weight of 0.02 to 0.3 parts by weight of at least one of strontium oxide and silicon dioxide. 2. The dielectric ceramic composition according to claim 1, wherein 0.03 to 0.3 parts by weight of manganese oxide is further added to 100 parts by weight of barium titanate. 3. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.5 parts by weight of lanthanum oxide is further added to 100 parts by weight of barium titanate. 4. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.5 part by weight of cerium oxide is further added to 100 parts by weight of barium titanate. 5. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.5 parts by weight of neodymium oxide is further added to 100 parts by weight of barium titanate. 6. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.5 parts by weight of samarium oxide is further added to 100 parts by weight of barium titanate. 7. The dielectric ceramic composition according to claim 1, wherein 0.05 to 0.5 parts by weight of dysprosium oxide is further added to 100 parts by weight of barium titanate. 8. The dielectric ceramic composition according to claim 1, further comprising 0.05 to 0.5 parts by weight of ytterbium oxide with respect to 100 parts by weight of barium titanate.