JP2511561B2 - Method for manufacturing barium titanate porcelain semiconductor - Google Patents

Description

The present invention relates to a titanic acid having a positive temperature coefficient of resistance at temperatures above the Curie point and excellent PTC characteristics due to its very low room temperature resistivity. The present invention relates to a method for manufacturing a barium porcelain semiconductor.

[Conventional technology]

By adding oxides such as lanthanum, tantalum, cerium, yttrium, bismuth, tungsten, silver, samarium, and dysprosium to barium titanate-based porcelain, obtain a porcelain semiconductor with a positive temperature coefficient of resistance (PTC characteristic). This is widely known from the past. It is also possible to improve the electrical characteristics of the porcelain semiconductor composition by adding silicon dioxide to the barium titanate-based porcelain semiconductor composition containing a rare earth element, tantalum, niobium, or antimony and firing it in the presence of oxygen. It has been proposed (see JP-A-53-59888).

[Problems to be Solved by the Invention]

However, in the above-described conventional method for manufacturing a barium titanate porcelain semiconductor, the semiconducting agent has a very low content rate during synthesis as compared with other components, specifically, about 1/1000 of the total weight. Yes, 1/60 of other ingredients in terms of weight
There is only 0 to 1/200. For this reason, the semiconducting agent must be weighed with high accuracy.

Further, since the content rate (mixing rate) of the semiconducting agent is low, it is extremely difficult to obtain sufficient homogeneity during mixing or reaction. For this reason, PT has a low resistivity at room temperature.
It is difficult to obtain C, its physical properties are not uniform, and the quality varies.

[Means for solving the problem]

A method for producing a barium titanate porcelain semiconductor according to the present invention is a method for producing a barium titanate porcelain semiconductor obtained by adding a semiconducting agent to a barium titanate substrate composition containing a Curie point transfer material and firing the semiconductor. As an agent
The Sb ₂ O ₅ sol is used for the barium titanate substrate composition.

The amount of Sb ₂ O ₅ sol added is in the range of 0.03 mol% to 1.0 mol%, and Sb ₂ O ₅ sol means a state in which ultrafine particles of Sb ₂ O ₅ are dispersed in water. . Sb ₂ O ₅ sol has a particle size of 0.02 μm, compared with a powder size of about 1 μm to 3 μm.
Very small, ~ 0.05 μm. The component concentration can be varied within the range of 10% to 70%. In addition, Sb ₂ O ₅ sol has a lower toxicity than Sb ₂ O _3, and since it is not necessary to handle powder, there is no harm due to dust, it is extremely easy to handle and it is a semiconducting agent that can greatly improve the working environment. Is.

[Work]

According to the above configuration, 0.03 added as a semiconducting agent
Since the particle size of Sb ₂ O ₅ particles in the mol% to 1.0 mol% Sb ₂ O ₅ sol is very small, uniform mixing and reaction are possible, semiconductor formation is easier, and at room temperature. Since the resistivity can be set smaller and variation in quality can be suppressed, it is possible to manufacture a low-resistance PTC element excellent in versatility that can be applied to a circuit having a small current capacity.

Also, Sb ₂ O ₅ particles are dispersed in water (for example, 5 wt.
% To 50 wt%), a large amount can be weighed, so that the weighing error of the semiconducting agent can be significantly reduced. For example, Sb in water
_If the wt% of ₂ O ₅ particles is 5 wt%, the amount can be weighed 20 times as much as the conventional amount. For this reason, the control amount of Sb ₂ O ₅ particles can be up to 5 decimal places (up to 3 decimal places in the past).

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

This example is a method for producing a barium titanate porcelain semiconductor, which comprises adding a semiconducting agent to a barium titanate substrate composition containing a Curie point transfer material and firing the composition.
As a semiconducting agent, 0.03 mol% to 1.0 mol% antimony pentoxide (Sb ₂ O ₅ ) based on the barium titanate substrate composition
It discloses how the resistivity at room temperature changes depending on the amount of Sb ₂ O ₅ sol added when a sol is used.

In this example, strontium carbonate (SrCO ₃ )
Etc. 0.03 mol% to 1.0 mol% antimony pentoxide (Sb ₂ O ₅ ) sol is added to the barium titanate substrate composition containing the Curie point transfer substance. Manganese carbonate (MnO ₃ ) is compounded as the material, and silicon dioxide (SiO ₂ ) or the like is compounded as the voltage-dependent stabilizer.

That is, a semiconducting agent (antimony pentoxide sol) was added to a barium titanate substrate composition, and this mixture was wet mixed in a ball mill for 6 hours to 48 hours, filtered,
After drying, at 1000 ℃ ~ 1300 ℃ for 1 ~ 3 hours,
Calcine. A raw material composition that decomposes by releasing gas is added to the calcined mixture, and the mixture is wet mixed in a ball mill for 6 to 48 hours and simultaneously ground. The above pulverized product is mixed in an aqueous solution containing a binder, the slurry is dried by a spray dryer to be granulated, and the granule is molded, and then the molded product is held at 1300 to 1400 ° C for 0 to 10 hours. Then, it is fired to obtain a barium titanate porcelain semiconductor.

Hereinafter, the present invention will be described in more detail based on Comparative Examples and Examples.

First, regarding the effect of the addition of antimony oxide (Sb ₂ O ₃ ) on the electrical characteristics of barium titanate porcelain semiconductor,
A description will be given below based on [Comparative Example 1] to [Comparative Example 3].

[Comparative Example 1] anhydrous barium carbonate (BaCO ₃ , BW-KL manufactured by Sakai Chemical Industry Co., Ltd.) 680.72
g, high-purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.) 29
0.12 g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co., Ltd.) 26.80 g, manganese carbonate (MnCO ₃ , manufactured by Wako Pure Chemical Industries, Ltd., 9
9.9% reagent) 0.2087 g, silicon dioxide (SiO ₂ , rare metalic, 99.9% reagent) 1.0908 g, and antimony oxide (Sb ₂ O ₃ , rare metallic, 99.9% reagent) 1.0584 g
Put in a 5 volume ball mill, add water 3.5 and diameter 2 to it.
Add 5 mm nylon coated iron balls and 2
Wet-mill for 4 hours, mix, filter, and mix 1
Dried at 30 ° C. The dry mixture was placed in a molding die [6.5 mm (diameter) x 45 mm (height)] and molded under a pressure of 150 kg / cm ² , and the molded product was placed in an electric furnace and heated at 180 ° C / hour. It was heated at a temperature rate and calcined at 1150 ° C. for 2 hours.

Put the pre-baked product in a vibrating ball mill and add water 0.7.
And 20 nylon balls with 15mm diameter nylon coating,
And 15 similar iron balls with a diameter of 10 mm are added, wet pulverized for 16 hours, 150 g of a 15 wt% polyvinyl alcohol (PVA) aqueous solution is added thereto, and the mixture is stirred for 2 hours, and then the slurry is spray-dried with a spray dryer. And granulated into granules having a diameter of about 50 μm. Mold the granules into a molding die [12.5 mm (diameter) x 35
mm (height)] and molded under a pressure of 1 ton / cm ² , and the molded product was fired under the following conditions.

Temperature range Temperature rising / falling conditions Room temperature to 800 ° C 145 ° C / hour temperature increase 800 ° C Hold for 2 hours 800 ° C to 1360 ° C 150 ° C / hour temperature rise 1360 ° C 1.5 hours hold 1360 ° C to 1000 ° C 360 ° C / hour Temperature drop of 1000 ℃ ~ 500 ℃ 245 ℃ / hour 550 ℃ End of temperature control After cooling to room temperature, the tablet-shaped molded disk is coated with Ohmic silver electrode (Degussa) at 580 ℃ An electrode was formed by baking for 5 minutes, a cover electrode (manufactured by Degussa) was applied on the electrode, and baking was performed at 560 ° C. for 5 minutes to obtain a barium titanate porcelain semiconductor.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.001Sb ₂ O ₃ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where the region showing the positive temperature coefficient of resistance occurs is 103
C., and the rising width of the resistance was 4 digits. At this time, the resistivity at room temperature was 19.50 Ω · cm.

Comparative Example 2 Anhydrous barium carbonate (BaCO ₃ ) 680.95 g, high-purity titanium dioxide (TiO ₂ ) 290.20 g, anhydrous strontium carbonate (SrC)
O ₃ ) 26.81 g, manganese carbonate (MnCO ₃ ) 0.2088 g, silicon dioxide (SiO ₂ ) 1.0911 g, and antimony oxide (Sb ₂ O ₃ ).
A barium titanate porcelain semiconductor sample was obtained in the same manner as in Comparative Example 1 except that 0.7409 g was used.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.0007Sb ₂ O ₃ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where the region showing the positive temperature coefficient of resistance occurs is 115
C., and the rising width of the resistance was three digits. At this time, the resistivity at room temperature was 3.4 kΩ · cm.

Comparative Example 3 Barium carbonate (BaCO ₃ ) 680.37 g, high-purity titanium dioxide (TiO ₂ ) 289.96 g, anhydrous strontium carbonate (SrC)
O ₃ ) 26.79 g, manganese carbonate (MnCO ₃ ) 0.2086 g, silicon dioxide (SiO ₂ ) 1.0902 g, and antimony oxide (Sb ₂ O ₃ ).
A barium titanate porcelain semiconductor sample was obtained in the same manner as in Comparative Example 1 except that 1.5868 g was used.

The raw material composition of the barium titanate porcelain is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0015Sb ₂ O ₃ This sample did not become a semiconductor by becoming an insulator, and the above physical properties could not be measured.

From the above [Comparative Example 1] to [Comparative Example 3], if the added amount of antimony oxide (Sb ₂ O ₃ ) is within the predetermined range,
It can be seen that the barium titanate porcelain semiconductor does not adversely affect the electrical characteristics. In other words, antimony oxide (Sb
_When the added amount of ₂ O ₃ ) is out of the above range, the rising width of the resistance of the barium titanate porcelain semiconductor becomes small and the barium titanate porcelain semiconductor becomes an insulator in proportion to the added amount. When the amount of antimony oxide (Sb ₂ O ₃ ) added is larger than the above range,
The barium titanate porcelain semiconductor may become an insulator.

By the way, a part of antimony oxide (Sb ₂ O ₃ ) in the raw material composition of the barium titanate porcelain semiconductor is transferred to antimony pentoxide (Sb ₂ O ₅ ) in the temperature rising process as a single substance. Therefore, the case where antimony pentoxide (Sb ₂ O ₅ ) sol is blended with a barium titanate substrate composition as a semiconducting agent will be described in detail below based on [Example 1] to [Example 4]. Explained. In [Example 1] to [Example 4], the composition of the raw materials other than the Sb ₂ O ₅ sol was the same as that in [Comparative Example 1] to [Comparative Example 3]. It is a thing.

Example 1 Anhydrous barium carbonate (BaCO ₃ , BW-KL manufactured by Sakai Chemical Industry Co., Ltd.) 680.65
1g, high-purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.) 2
90.076 g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co., Ltd.) 26.798 g, manganese carbonate (MnCO ₃ , manufactured by Wako Pure Chemical Industries, Ltd.,
99.9% reagent) 0.2086 g, silicon dioxide (SiO ₂ , manufactured by Rare Metallic Co., Ltd., 99.9% reagent) 1.0906 g, and antimony pentoxide sol (Sb ₂ O ₅ , manufactured by Nissan Chemical Industries, Ltd., A-1550 48 wt.
%) Put 2.4466g in a 5 volume ball mill and add water to it.
Nylon coated iron ball 40 with 3.5 and 25 mm diameter
Add and add, wet crush for 24 hours, mix, then filter,
The mixture was dried at 130 ° C. Put the dry mixture in a molding die [6.5 mm (diameter) x 45 mm (height)] and
It was molded under a pressure of 50 kg / cm ² , the molded product was placed in an electric furnace, heated at a heating rate of 180 ° C./hour, and calcined at 1150 ° C. for 2 hours.

Put the pre-baked product in a vibrating ball mill and add water 0.7.
And 20 nylon balls with 15mm diameter nylon coating,
And 15 similar iron balls with a diameter of 10 mm were added and wet pulverized for 16 hours, 150 g of a 15 wt% polyvinyl alcohol (PVA) aqueous solution was added, and the mixture was stirred for 2 hours and then the slurry was spray-dried with a spray dryer. And granulated into granules having a diameter of 50 μm. Mold the granules into a molding die [12.5 mm (diameter) x 35
mm (height)] and molded under a pressure of 1 ton / cm ² , and the molded product was fired under the following conditions.

Temperature range Temperature rising / falling conditions Room temperature to 800 ° C 145 ° C / hour temperature increase 800 ° C Hold for 2 hours 800 ° C to 1360 ° C 150 ° C / hour temperature rise 1360 ° C 1.5 hours hold 1360 ° C to 1000 ° C 360 ° C / hour Temperature drop 1000 ℃ ~ 500 ℃ 245 ℃ / hour 550 ℃ End of temperature control After cooling to room temperature, tablet-shaped molded disk surface is coated with ohmic silver electrode (Degussa) at 580 ℃ An electrode was formed by baking for 5 minutes, a cover electrode (manufactured by Degussa) was applied on the electrode, and further baked at 560 ° C. for 5 minutes to obtain a barium titanate porcelain semiconductor.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.001Sb ₂ O ₅ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where a region showing a positive resistance temperature coefficient occurs 111 ℃
The rising width of the resistance was two digits. At this time, the resistivity at room temperature was 6.62 Ω · cm.

Example 2 Anhydrous barium carbonate (BaCO ₃ ) 680.89 g, high-purity titanium dioxide (TiO ₂ ) 290.17 g, anhydrous strontium carbonate (SrC)
O ₃ ) 26.80 g, manganese carbonate (MnCO ₃ ) 0.208 g, silicon dioxide (SiO ₂ ) 1.091 g, and antimony pentoxide sol (Sb
_A barium titanate porcelain semiconductor sample was obtained in the same manner as in Example 1 except that 1.712 g of ₂ O ₅ ) was used.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.0007Sb ₂ O ₅ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where the region showing the positive resistance temperature coefficient occurs is 115
At ° C, the rising width of the resistance was three digits. At this time, the resistivity at room temperature was 44.54 Ω · cm.

Example 3 Anhydrous barium carbonate (BaCO ₃ ) 680.41 g, high-purity titanium dioxide (TiO ₂ ) 289.97 g, anhydrous strontium carbonate (SrC)
O ₃ ) 26.78 g, manganese carbonate (MnCO ₃ ) 0.208 g, silicon dioxide (SiO ₂ ) 1.090 g, and antimony pentoxide sol (Sb
_A barium titanate porcelain semiconductor sample was obtained in the same manner as in Example 1 except that 3.179 g of ₂ O ₅ ) was used.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.0013Sb ₂ O ₅ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where the region showing the positive resistance temperature coefficient occurs is 110
At ° C, the rising width of the resistance was two digits. At this time, the resistivity at room temperature was 5.42 Ω · cm.

Example 4 Anhydrous barium carbonate (BaCO ₃₎ 680.25g, high-purity titanium dioxide (TiO ₂₎ 289.90g, strontium carbonate anhydrous (SrC
O ₃ ) 26.78 g, manganese carbonate (MnCO ₃ ) 0.2081 g, silicon dioxide (SiO ₂ ) 1.090 g, and antimony pentoxide sol (Sb
_A barium titanate porcelain semiconductor sample was obtained in the same manner as in Example 1 except that 3.67 g of ₂ O ₅ ) was used.

The compounding composition of the raw material of this barium titanate porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ ＋ 0.0005MnO ₂ ＋ 0.005SiO ₂ ＋ 0.0015Sb ₂ O ₅ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) where the region showing the positive resistance temperature coefficient occurs is 105
At ° C, the rising width of the resistance was one digit. At this time, the resistivity at room temperature was 4.26 × 10 ⁶ Ω · cm.

From the above, the results of [Example 1] to [Example 4] are summarized in Table 1. As is clear from Table 1, by using antimony pentoxide (Sb ₂ O ₅ ) sol as a semiconducting agent for barium titanate substrate composition (characteristics shown by the broken line in FIG. 2), The resistivity at room temperature can be made very small with a smaller amount than when antimony oxide (Sb ₂ O ₃ ) powder is used (characteristics shown by the solid line in FIG. 2) (see Comparative Examples 1 and 2). it can. In addition, Sb of the above barium titanate porcelain semiconductor
₂ O ₅ addition amount dependency ([Example 1] to [Example 4]]
(Characteristics corresponding to each sample) are as shown in FIG. That is, as shown in FIG. 1, when the amount of Sb ₂ O ₅ added to the barium titanate porcelain semiconductor is smaller than 0.03 mol% or larger than 0.15 mol%, the resistivity (specific resistance) at room temperature is Noticeably larger. Therefore, it is understood that the addition amount of Sb ₂ O ₅ is preferably in the range of 0.03 mol% to 0.15 mol%.

Here, methods for measuring various physical properties of the above-mentioned various barium titanate porcelain semiconductor samples having different raw material composition will be described.

(1) Curie point measurement A barium titanate porcelain semiconductor sample was attached to a sample holder for measurement, and a measuring tank (MINI-SUBZERO MC-810P
The sample was mounted in Tabay Espec Co., Ltd., and the change in the electrical resistance of the sample with respect to the temperature change from −50 ° C. to 190 ° C. was measured using a DC resistance meter (Multimeter 3478A YHP).

From the electrical resistance-temperature plot obtained by the measurement,
The temperature at which the resistance value is twice the resistance value at room temperature was the Curie point.

(2) Measurement of room temperature resistivity A sample of barium titanate porcelain semiconductor was measured for electrical resistance in a measuring tank at 25 ° C using a DC resistance meter (Multimeter 3478A YHP).

In the preparation of barium titanate porcelain semiconductor samples,
The size (diameter and thickness) of the sample was measured before applying the electrode, and the specific resistance (ρ) was calculated by the following formula, which was taken as the resistivity.

ρ: R · S / t ρ: Specific resistance (resistivity) [Ω · cm] R: Measured value of electrical resistance [Ω] S: Area of electrode [cm ² ] t: Thickness of sample [cm] (3 ) Measurement of the rising width of the resistivity The measurement of the change in the electrical resistance of the sample with respect to the temperature change of the Curie point measurement (-50 ° C to 190 ° C) is continued until the temperature exceeds 200 ° C, and the resistivity-temperature plot is shown. In the above, the resistivity at the sudden rise of the electric resistance at the Curie point was compared with the resistivity at 200 ° C., and the logarithmic ratio of the digits was taken as the rise width of the resistivity.

The barium titanate porcelain semiconductor according to the present invention,
Since it has a low resistivity at room temperature, it can be used as a low resistance PTC element in a circuit with a small current capacity,
For example, it can be used as a comparator of a thermal fuse switching power supply. The barium titanate porcelain semiconductor according to the present invention is, in addition to the above, a protection circuit for an electrolytic capacitor, a color TV automatic degaussing device, a motor starting device for automobiles, an electronic crisis overheat prevention device, a delay element, a timer,
It can be used for liquid level gauges, contactless switches, relay contact protectors, etc.

[Effects of the Invention] In the method for producing a barium titanate porcelain semiconductor according to the present invention, 0.03 mol% to 1.0 mol% of Sb ₂ O ₅ sol is added to the barium titanate base composition as a semiconductor agent. It is composed.

Therefore, 0.03 mol% to 1.
Since the particle size of Sb ₂ O ₅ particles in 0 mol% Sb ₂ O ₅ sol is very small, uniform mixing and reaction are possible, and it is possible to easily and homogenize semiconductors and to obtain resistance at room temperature. The rate can be set smaller, and the physical properties such as the withstand voltage due to the uniformization of semiconductors can be made uniform, and variations in quality can be suppressed, making it versatile enough to be used in circuits with small current capacity. An excellent low resistance PTC element can be manufactured.

Further, since the Sb ₂ O ₅ particles are dispersed in water, a large amount of Sb ₂ O ₅ particles can be weighed, so that the weighing error of the semiconducting agent is significantly reduced. In addition, the control amount of Sb ₂ O ₅ particles can be up to 5 decimal places (up to 3 decimal places was the limit in the past).

Furthermore, since the raw material cost of Sb ₂ O ₅ sol is much lower (2 to 3 digits lower) compared to Sb ₂ O ₃ powder and Sb ₂ O ₃ powder, it is possible to reduce the cost as a whole. , Sb ₂ O ₅ powder is less toxic than the Sb ₂ O ₅ powder, and since it is not necessary to handle the powder, there is no harm due to dust, the handling is extremely easy, and the working environment can be greatly improved.

[Brief description of drawings]

1 and 2 show one embodiment of the present invention. FIG. 1 is an explanatory view showing the dependency of the specific resistance of the barium titanate porcelain semiconductor according to the present invention on the added amount of antimony pentoxide sol. FIG. 2 shows the Sb addition amount dependency of the specific resistance of the barium titanate porcelain semiconductor according to the present invention and the S addition amount dependency of the specific resistance when Sb ₂ O ₃ powder is used as a semiconducting agent. FIG.

Claims (1)

(57) [Claims] 1. A method for producing a barium titanate porcelain semiconductor, comprising adding a semiconducting agent to a barium titanate substrate composition containing a Curie point transfer substance, and firing the barium titanate ceramic composition. On the other hand, a method for producing a barium titanate porcelain semiconductor, which comprises using 0.03 mol% to 1.0 mol% Sb ₂ O ₅ sol.