JPH01149415A - Semiconductor porcelain substance - Google Patents

Abstract

PURPOSE:To obtain the title porcelain substance having excellent electric characteristics by a method wherein the composition consisting of the specific quantity of bismuth oxide and rubidium compound is diffused into the crystal grain boundary of semiconductor porcelain. CONSTITUTION:The composition, consisting of bismuth oxide Bi2O3 of 10-90molar%, a rubidium compound of 10-90molar% is coated as a diffusion substance, and they are sintered in an atmospheric air. When the mixture is used as a diffusion substance, dielectric constant can be improved by 1.3 and insulation resistivity can also be improved remarkably when compared with the previous case in which a bismuth oxide single unit is used as a diffusion substance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor ceramic material in which a dielectric layer is provided at the grain boundaries of the semiconductor ceramic material.

[Prior art]

In recent years, grain boundary dielectric type semiconductor ceramic materials, in which a highly insulating layer is provided as a dielectric material at the grain boundaries of semiconductor ceramics mainly composed of strontium titanate (SrTi01), have been used for capacitors,
Widely used in varistors, thermistors, etc. This semiconductor porcelain material was first made of strontium titanate (
SrTi01) as the main material and niobium oxide (Nb20S) as a valence control agent.

Indium oxide (YzOz), etc. are added, and silicon oxide (SiOz) and aluminum oxide (SiOz) are added as sintering aids.
A semiconductor porcelain is obtained by adding materials such as AlzOs) and sintering in a reducing atmosphere, and then a dielectric layer is provided at the grain boundaries of this semiconductor porcelain (manganese oxide (MnOz), copper monoxide (
Cub), bismuth oxide (BizOs), and other metal oxides were obtained by thermally diffusing metal oxides as the diffusion substance (Japanese Patent Publication No. 5B-27649, Japanese Patent Publication No. 58-23922).
Publication No.).

[Problem that the invention seeks to solve]

The electrical properties of the resulting semiconductor ceramic material [dielectric constant (εmPp
L dielectric loss tangent (tan δ), insulation resistivity (ρ1□), etc.]
There is a difference. For example, manganese oxide (
Semiconductor ceramic materials obtained using MnOt) or copper oxide (Cub) have high insulation resistivity, but have high dielectric loss tangents and low dielectric constants. On the other hand, when bismuth oxide (BizOs) is used as the diffusion material, the dielectric loss tangent is low and the dielectric constant is high, but the insulation resistivity is low.

Furthermore, when using a mixture of bismuth oxide (BizO) and copper oxide (Cub) as a diffusion material, the average Although each electrical characteristic improved, it could not be said that sufficient characteristic values were achieved.

Thus, good results for all electrical characteristics (
A semiconductor ceramic material having high dielectric constant and insulation resistivity and low dielectric loss tangent has not yet been obtained.

As a result of investigating the electrical characteristics of semiconductor ceramic materials using various materials as diffusion materials, the present inventor found that bismuth oxide (BizO:+) was used as a diffusion material,
It has been found that when a mixture with a rubidium-based compound is used, a semiconductor ceramic material having good electrical properties can be obtained.

The present invention was made based on this knowledge, and it is an object of the present invention to provide a semiconductor ceramic material that can obtain good results in all of the above-mentioned electrical properties.

[Means for solving problems]

In the semiconductor ceramic material according to the present invention, a composition comprising 10 to 90 mol % of bismuth oxide (BizOs) and 10 to 90 mol % of a rubidium compound is diffused into the grain boundaries of the semiconductor porcelain. It is characterized by forming a dielectric layer thereon.

[Effect]

When the above-described composition is employed as a diffusing substance that is thermally diffused to form a dielectric layer at the grain boundaries of semiconductor porcelain, the dielectric constant and insulation resistivity of the resulting semiconductor porcelain material are greatly improved. Moreover, the dielectric loss tangent is sufficiently low.

〔Example〕

Hereinafter, embodiments in which the present invention is applied to, for example, the manufacture of capacitors will be specifically described.

First, a method for manufacturing the semiconductor ceramic material of the present invention (hereinafter referred to as the "present invention material") will be explained. For example, strontium titanate (SrTiOz) and niobium oxide (NbzOs)
and 0.1 to 2 mol% of manganese oxide (MnOg), respectively.
After mixing thoroughly, the mixture is pressure-molded into a disk shape with a diameter of 10 mm and a thickness of 0.8 nm. After this, hydrogen 1-1
140 in a reducing atmosphere consisting of 5% nitrogen and 99-85% nitrogen.
Semiconductor porcelain is produced by firing at a temperature of 0 to 1540°C for 4 to 10 hours. Next, a diffusion substance (a mixture of bismuth oxide (BizO+) and a rubidium-based compound, such as rubidium carbonate (RbzC(1+)) is applied to one side of the semiconductor porcelain and heated at 1000 to 1350°C for 1 to 2 hours to diffuse it. The material is thermally diffused.Finally, silver paste is deposited on both sides of the semiconductor porcelain material obtained in this way, and
It is baked at about ℃ to form a silver electrode and a capacitor is obtained.

In addition to rubidium carbonate (RbzCO3), rubidium oxide (RbzO) and dirubidium trioxide (Rb, O,
, rubidium peroxide (Rb!O□), rubidium superoxide (RbO□), rubidium hydroxide (RbOH), and the like are used one or more kinds.

Bismuth oxide (Bit (h) and rubidium carbonate (Rbz)
Table 1 below shows the electrical properties of semiconductor ceramic materials obtained by applying mixtures with CO3) to semiconductor ceramics at various composition ratios. In addition, the dielectric constant (ε1.p) and dielectric loss tangent (
tan δ) is a value measured at a frequency of 1 kHz and a voltage of 1 ■, and insulation resistivity (ρ, 1) is a value determined from a DC 25 V 1 minute value. Further, the characteristic values in the table indicate the average values of 10 samples at various composition ratios.

(Left below) From Table 1, Table 2, Bismuth oxide (Big(h) 10-90
Mol%, rubidium carbonate (RbzCOi) 10~gO
It can be seen that good electrical properties are obtained within the range of mol %.

It can also be seen that when bismuth oxide (Bias3) is less than 10 mol% or when it is 95 mol% or more, the dielectric constant is lowered. In addition, bismuth oxide alone
It can be seen that the insulation resistivity decreases significantly and the dielectric loss tangent of rubidium carbonate alone increases.

Furthermore, Table 1 shows that the electrical properties of the material of the present invention using a mixture of 20 mol % bismuth oxide (Bias) and 80 mol % rubidium carbonate (RbzCO:+) as a diffusion material are similar to those of bismuth oxide (BizO,) alone. It can also be seen that the dielectric constant is improved by 1.3 times and the insulation resistivity is improved by two orders of magnitude compared to the conventional example in which the material was used as a diffusion material.

Table 2 shows the electrical characteristic values when manganese oxide (MnOz) and copper oxide (CuO) are each diffused as a single diffusion substance as a comparative example. By comparison with the comparative examples in the table, the improvement in each electrical property of the substance of the present invention becomes clearer.

Further, the above-mentioned material of the present invention has the advantage that it can be obtained by a simple manufacturing process of applying a diffusive substance and firing in the atmosphere.

In the above embodiment, rubidium carbonate was used as one of the diffusing substances, but other rubidium hydroxide, rubidium oxide, dirubidium trioxide, rubidium peroxide, rubidium superoxide, or two of these may also be used. It was confirmed that the above mixture had substantially the same effect as the above-mentioned example within the range of 10 to 90 mol %.

Further, in the above-described embodiment, silver electrodes were formed by printing silver paste on both sides of the semiconductor ceramic material and baking the same, but it goes without saying that other known electrode materials may be used. Furthermore, the firing atmosphere during the production of semiconductor porcelain is not limited to an atmosphere consisting of 1 to 15% hydrogen and 99 to 85% nitrogen as in the above-mentioned example, but as long as the atmosphere can sufficiently convert the sample into a semiconductor. Other atmospheres are also acceptable.

Furthermore, in this example, the case where the substance of the present invention is used in a capacitor has been described, but it goes without saying that the present invention is not limited to this and may be used in other applications such as varistors and thermistors. .

〔effect〕

As detailed above, in the semiconductor ceramic material of the present invention, a composition consisting of 10 to 90 mol% of bismuth Mide (Big(h)) and 10 to 90 mol% of a rubidium-based compound is used as a diffusing substance. , the semiconductor ceramic material can have good results in electrical properties such as dielectric constant, dielectric loss tangent, and insulation resistivity.

Claims (1)

[Claims] 1. Bismuth oxide (Bi_2
O_3) 10 to 90 mol% and rubidium compound 10
A semiconductor ceramic material, characterized in that a composition comprising ~90 mol % is diffused to form a dielectric layer at the grain boundaries.