JP3031104B2 - Dielectric porcelain composition - Google Patents

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, and a small dielectric loss.

[0002]

2. Description of the Related Art Hitherto, as a material for a high dielectric constant ceramic capacitor, a dielectric ceramic composition containing barium titanate as a main component has been widely used. Among them, materials having a small temperature change in dielectric constant include barium titanate-bismuth based, barium titanate-niobium pentoxide-manganese dioxide based (JP-A-51-76597),
Numerous compositions are known.

Further, in order to meet the recent demand for a multilayer ceramic capacitor having a small size and a large capacity, the dielectric constant of a dielectric material and the thickness of a dielectric layer are rapidly progressing. Therefore, with a high dielectric constant, the temperature change of the dielectric constant is small,
The demand for a dielectric material having a small dielectric loss has become extremely large.

[0004]

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

In general, in a ferroelectric material such as barium titanate, as the applied electric field intensity 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 signal voltage characteristics are poor in the conventional dielectric ceramic composition, and the signal voltage is poor. There has been a problem that the dielectric loss rapidly increases with an increase in the voltage, and the standard cannot be satisfied.

An object of the present invention is to provide a dielectric ceramic composition having a high dielectric constant, a small change in temperature, a small dielectric loss, and a good signal voltage characteristic. And

[0007]

In order to achieve this object, a dielectric porcelain composition of the present invention is produced by a hydrothermal synthesis method,
100 parts by weight of barium titanate whose specific surface area was adjusted to 0.8 to 2.4 m ² / g by heat treatment,
0.8 to 2.0 parts by weight of niobium, niobium pentoxide, acid
The weight ratio of nickel oxide and cobalt oxide is 3 ≦ nio pentoxide
Bu / (nickel oxide + cobalt oxide) ≤ 8 (however, acid
Excluding 0 parts by weight of nickel oxide and 0 parts by weight of cobalt oxide
Nickel oxide and cobalt oxide are added so that
Along with lanthanum oxide, cerium oxide, neo oxide
Indium, samarium oxide, dysprosium oxide,
More than one of tritium and praseosium oxide
It is formed by adding 0.05 to 0.50 parts by weight.
You .

[0008]

The dielectric ceramic composition of the present invention is produced by a hydrothermal synthesis method, and has a specific surface area of 0.8 to 2.4 m by heat treatment.
² / using g of very good barium titanate crystalline high purity was adjusted to a specific amount of niobium pentoxide therein, nickel oxide, by adding cobalt oxide, 280
A high dielectric constant of 0 or about 4000, it is possible to temperature change of the dielectric constant is small, to obtain the dielectric loss was 2.5% or less and have small Yu characteristics when the signal voltage is applied 50 Vrms / mm . Then, by 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 above-described properties. be able to
The effect is obtained.

[0009]

(Example 1) This example corresponds to the first aspect of the present invention, and a specific amount of niobium pentoxide and barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. Nickel oxide and cobalt oxide are added, and lanthanum oxide is added.
This is a solution to the problem.

[0010] The particle size 0.1μm generated by hydrothermal synthesis, a purity of 99.99% or more of barium titanate fine powder 105
Barium titanate whose powder was calcined at 0 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used . Against barium titanate 100g above SL, niobium pentoxide calculated as Nb ₂ O _5, nickel oxide in terms of NiO, a cobalt oxide in Co ₃ O ₄ conversion, lanthanum oxide with La ₂ O ₃ (Table 1 ) Was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. In addition,
In the example, cobalt oxide was added as Co ₃ O ₄ ,
It may be added in other forms such as oO.
The same effect can be obtained if the amount is the same. (Table 1)
Is niobium pentoxide, nickel oxide, cobalt oxide,
The lanthanum respectively expressed simply Nb, Ni, Co, and La. This was mixed with pure water by a ball mill in which a zirconia ball having a diameter of 5 mm was placed in a polyethylene container.
Mix for 0 hours. After mixing, the slurry is added to the dried powder for 5 minutes.
% PVA (polyvinyl alcohol) aqueous solution was added at 9% by weight and granulated. The granulated powder was placed in a mold and formed into a disk having a diameter of 15 mm and a thickness of 0.5 mm at a pressure of 1 ton / cm ³ . The obtained molded body was fired at 1300 to 1400 ° C. for 2 hours, and a silver electrode was baked and applied to obtain a sample for measurement. Samples whose sintering density did not reach 95% of the theoretical density at a sintering temperature of 1400 ° C. or less were not sintered, and the measurement of the following electrical characteristics was omitted. At room temperature, the capacitance and dielectric loss of the sample were measured at 1 Vrms and 1 kHz, and the dielectric constant was determined from the capacitance. The signal voltage characteristics of the dielectric loss were measured by applying a 1 kHz signal at 50 Vrms / mm.

[0011] (Table 2) 1300 ℃ and 1330 ℃ firing
5 shows the sintering density, the dielectric constant at room temperature after firing at 1330 ° C. , the dielectric loss, and the signal voltage characteristics of dielectric loss . still,
In Tables 1 and 2, samples marked with # are out of the scope of the present invention and are comparative examples.

[0012]

[Table 1]

[0013]

[Table 2]

As is clear from Tables 1 and 2, lanthanum oxide was added to 100 parts by weight of barium titanate.
Improved sinterability by adding 0.05 parts by weight or more
Is done . However, if the amount exceeds 0.50 parts by weight, it is induced.
Significant decrease in electric conductivity, sintering when less than 0.05 parts by weight
Since there was no effect of improving the sex, it was excluded from the claims.

Example 2 This example also corresponds to the first aspect of the present invention, in which a specific amount of niobium pentoxide, a specific amount of niobium pentoxide, is added to barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment. Nickel oxide,
The problem was solved by adding cobalt oxide and further adding cerium oxide .

The particle size 0.1μm generated by hydrothermal synthesis, a purity of 99.99% or more of barium titanate fine powder 105
Barium titanate whose powder was calcined at 0 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. With respect to the barium titanate 100 g, with niobium pentoxide calculated as Nb ₂ O _5, nickel oxide in terms of NiO, a cobalt oxide in Co ₃ O ₄ conversion, the cerium oxide CeO ₂ with terms (Table 3) The indicated amount was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Also,
In this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in other forms such as CoO, and the same effect can be obtained as long as the amount of metallic cobalt is the same. (Table 3) also shows niobium pentoxide, nickel oxide, cobalt oxide,
Cerium oxide was simply expressed as Nb, Ni, Co, and Ce , respectively. A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 4 shows the sintering densities at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature after 1330 ° C. firing, dielectric loss, and signal voltage characteristics of dielectric loss. still,
In Tables 3 and 4, samples marked with # are out of the scope of the present invention and are comparative examples.

[0018]

[Table 3]

[0019]

[Table 4]

As is clear from Tables 3 and 4, cerium oxide was added to 100 parts by weight of barium titanate.
By adding 0.05 parts by weight or more, the sinterability is improved. However, when the addition amount exceeds 0.50 parts by weight, the dielectric constant is remarkably reduced, 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 claims.

Example 3 This example also corresponds to the first aspect of the present invention, wherein a specific amount of niobium pentoxide, a specific amount of niobium pentoxide, Nickel oxide,
The problem has been solved by adding cobalt oxide and further adding neodymium oxide .

The particle size 0.1μm generated by hydrothermal synthesis, a purity of 99.99% or more of barium titanate fine powder 105
Barium titanate whose powder was calcined at 0 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. With respect to the barium titanate 100 g, pentoxide niobium calculated as Nb ₂ O _5, nickel oxide in terms of NiO, a cobalt oxide in Co ₃ O ₄ conversion, neodymium oxide Nd ₂ O ₃ in terms of (TABLE 5 ) Was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Further, in this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in another form such as CoO, and the same effect can be obtained as long as the amount of metal cobalt is the same. (Table 5) also shows niobium pentoxide, nickel oxide, cobalt oxide,
Neodymium oxide is simply Nb, Ni, Co, Nd
It was expressed. A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 6 shows the sintering densities at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature after 1330 ° C. firing, dielectric loss, and signal voltage characteristics of dielectric loss. still,
In Tables 5 and 6, samples marked with # are out of the scope of the present invention and are comparative examples.

[0024]

[Table 5]

[0025]

[Table 6]

As is clear from Tables 5 and 6, sinterability is improved by adding 0.05 parts 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 reduced, 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 claims.

Example 4 This example also corresponds to the first aspect of the present invention, and a specific amount of niobium pentoxide and barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment are added to the barium titanate. Nickel oxide,
The problem has been solved by adding cobalt oxide and further adding samarium oxide .

A particle diameter of 0.1 μm produced by a hydrothermal synthesis method,
Barium titanate fine powder having a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. For 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Nickel oxide is converted to NiO, and cobalt oxide is converted to Co ₃ O ₄
In conversion, samarium oxide was weighed in the amount shown in (Table 7) in SmO ₂ O ₃ conversion . The cobalt oxide used had a purity of 73 to 74% as metallic cobalt.
Further, in this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in another form such as CoO, and the same effect can be obtained as long as the amount of metal cobalt is the same.
Also in Table 7, niobium pentoxide, nickel oxide, cobalt oxide, and samarium oxide are simply referred to as Nb, Ni, Co,
Sm . A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 8 shows the sintering densities at 1300 ° C. and 1330 ° C., the dielectric constant at room temperature after 1330 ° C., the dielectric loss, and the signal voltage characteristics of the dielectric loss. still,
In Tables 7 and 8, samples marked with # are out of the scope of the present invention and are comparative examples.

[0030]

[Table 7]

[0031]

[Table 8]

As is clear from Tables 7 and 8, the sinterability is improved by further adding 0.05 parts 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 reduced, 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 claims.

Example 5 This example also corresponds to the first aspect of the present invention, and a specific amount of niobium pentoxide and barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment are added to Nickel oxide,
The problem was solved by adding cobalt oxide and further adding dysprosium oxide .

The particle size 0.1μm generated by hydrothermal synthesis, a purity of 99.99% or more of barium titanate fine powder 105
Barium titanate whose powder was calcined at 0 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. With respect to the barium titanate 100 g, pentoxide niobium calculated as Nb ₂ O _5, nickel oxide in terms of NiO, a cobalt oxide in Co ₃ O ₄ conversion, dysprosium oxide Dy ₂ O ₃ in terms of (TABLE 9 ) Was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt.
Further, in this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in another form such as CoO, and the same effect can be obtained as long as the amount of metal cobalt is the same.
(Table 9) even niobium pentoxide, nickel oxide, cobalt oxide, simply oxide dysprosium respectively Nb, Ni, C
o and Dy . A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 10 shows the sintering densities at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature after 1330 ° C. firing, dielectric loss, and signal voltage characteristics of dielectric loss.
In Tables 9 and 10, the samples marked with # are out of the scope of the present invention and are comparative examples.

[0036]

[Table 9]

[0037]

[Table 10]

As apparent from (Table 9) and (Table 10),
Dysprosium oxide to 100 parts by weight of barium titanate
By further addition of um or 0.05 parts by weight,
Sinterability is improved. However, when the addition amount exceeds 0.50 parts by weight, the dielectric constant is remarkably reduced, 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 claims.

Example 6 This example also corresponds to the first aspect of the present invention, in which a specific amount of niobium pentoxide and barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment are added. Nickel oxide,
The problem was solved by adding cobalt oxide and further adding yttrium oxide .

A particle diameter of 0.1 μm produced by a hydrothermal synthesis method,
Barium titanate fine powder having a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. For 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Nickel oxide is converted to NiO, and cobalt oxide is converted to Co ₃ O ₄
In terms of the oxide ytterbium Yb ₂ O ₃ in terms of (TABLE 1
The amount shown in 1) was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Further, in this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in another form such as CoO, and the same effect can be obtained as long as the amount of metal cobalt is the same. In Table 11, niobium pentoxide, nickel oxide, cobalt oxide, and yttrium oxide are simply referred to as Nb and N , respectively.
i, Co, and Yb . A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 12 shows the sintering densities at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature after 1330 ° C. firing, dielectric loss, and signal voltage characteristics of dielectric loss.
In Tables 11 and 12, samples marked with # are out of the scope of the present invention and are comparative examples.

[0042]

[Table 11]

[0043]

[Table 12]

As is clear from Table 11 and Table 12, it was oxidized with respect to 100 parts by weight of barium titanate.
The sinterability is improved by further adding 0.05 % by weight or more of rivium . However, when the addition amount exceeds 0.50 parts by weight, the dielectric constant is remarkably reduced, 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 claims.

Example 7 This example also corresponds to the first aspect of the present invention, in which a specific amount of niobium pentoxide and barium titanate produced by a hydrothermal synthesis method and having a specific surface area adjusted by heat treatment are added. Nickel oxide,
The problem has been solved by adding cobalt oxide and further adding praseosium oxide .

A particle diameter of 0.1 μm produced by a hydrothermal synthesis method,
Barium titanate fine powder having a purity of 99.99% or more
Barium titanate whose powder was calcined at 50 ° C. and the specific surface area was adjusted to 1.2 m ² / g was used. For 100 g of the above barium titanate, niobium pentoxide was converted into Nb ₂ O ₅ ,
Nickel oxide is converted to NiO, and cobalt oxide is converted to Co ₃ O ₄
In terms of the oxide Puraseoshiumu Pr ₂ O ₃ in terms of (TABLE 1
The amount shown in 3) was weighed. The cobalt oxide used had a purity of 73 to 74% as metallic cobalt. Further, in this embodiment, the cobalt oxide is added as Co ₃ O ₄ , but it may be added in another form such as CoO, and the same effect can be obtained as long as the amount of metal cobalt is the same. (Table 13) also uses niobium pentoxide, nickel oxide, cobalt oxide, and praseosium oxide as Nb and N , respectively.
i, Co, and Pr . A sample was prepared and evaluated by the same procedure as described below (Example 1).

Table 14 shows the sintering densities at 1300 ° C. and 1330 ° C. firing, the dielectric constant at room temperature after 1330 ° C. firing, dielectric loss, and signal voltage characteristics of dielectric loss.
In Tables 13 and 14, samples marked with # are out of the scope of the present invention and are comparative examples.

[0048]

[Table 13]

[0049]

[Table 14]

As is clear from Tables 13 and 14, 100 parts by weight of barium titanate was used to place oxide placebo.
By further adding 0.05 part by weight or more of osmium, sinterability is improved. However, when the addition amount exceeds 0.50 parts by weight, the dielectric constant is remarkably reduced, 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 claims.

[0051] In the above embodiments, additives and to acid <br/> lanthanum, cerium oxide, neodymium oxide, samarium oxide, dysprosium oxide, oxide ytterbium, the kind of the oxide Puraseoshiumu, barium titanate 1
Although the case where 0.05 to 0.50 parts by weight is added to 00 parts by weight has been described, even when two or more of these additives are added at the same time, the total amount of the additives is 0.05 to 0.1%.
When the amount is within the range of 50 parts by weight, the same effects as those of the above embodiments can be obtained.

[0052]

According to the present invention as described above, by generating with hydrothermal synthesis method, it is used a good barium titanate crystalline high purity was appropriately adjusted by Ri specific surface area in the heat treatment,
A dielectric ceramic composition having a high dielectric constant of 2800 to 4000, a small temperature change in the dielectric constant, and a small dielectric loss of 2.5% or less when a signal voltage of 50 Vrms / mm is applied. Can be. In addition, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide,
Add at least one of dysprosium oxide, ytterbium oxide, and praseosium oxide in a predetermined amount
Thereby , sinterability can be improved.

Therefore, it can be put to practical use as a dielectric material for a ceramic capacitor. In particular, in the case of a multilayer ceramic capacitor, since the dielectric layer can be made thinner, it is possible to easily realize a small size and a large capacity. It is.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takeshi Iino 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-258610 (JP, A) JP-A-2- 258671 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01G 4/12 358

Claims (1)

(57) [Claims] 1. A generated by the hydrothermal synthesis method, the I Ri ratio table <br/> area heat treatment on 0.8~2.4m ^2/100 parts by weight of barium titanate adjusted to g, pentoxide 0.8 niobium
2.0 parts by weight , and the weight ratio of niobium pentoxide, nickel oxide, and cobalt oxide is 3 ≦ niobium pentoxide / (nickel oxide + cobalt oxide) ≦ 8 (however, excluding 0 part by weight of nickel oxide, 0% by weight of cobalt oxide) Acid )
Nickel oxide and cobalt oxide
Lanthanum, cerium oxide, neodymium oxide, oxide summary
, Dysprosium oxide, ytterbium oxide, oxidation
0.05 to 0.50 of one or more of praseosium
A dielectric porcelain composition to which parts by weight are added .