JPH0462902A - Manufacture of barium titanium porcelain semiconductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides titanic acid which has a positive temperature coefficient of resistance at temperatures above the Curie point and has excellent PTC properties due to very low room temperature resistivity. The present invention relates to a method for manufacturing a barium ceramic semiconductor.

[Conventional technology]

By adding oxides such as lanthanum, tantalum, cerium, yttrium, bismuth, tungsten, silver, zamarium, and dysprosium to barium titanate ceramic, a ceramic semiconductor having a positive temperature coefficient of resistance (PTC characteristic) is obtained. This has been widely known for a long time. Additionally, the electrical properties of the ceramic semiconductor composition can be improved by adding silicon dioxide to a barium titanate ceramic semiconductor composition containing a rare earth element, tantalum, niobium, or antimony and firing it in the presence of oxygen. It has been proposed (see Japanese Patent Laid-Open No. 51-59888).

[Problem to be solved by the invention]

However, in the above-mentioned conventional method for manufacturing barium titanate ceramic semiconductors, the content of the semiconducting agent during synthesis is very low compared to other components per liter, specifically about 1/1000 of the total weight. In terms of weight, it is only about 1/600 to 1/200 of the other components. For this reason, the semiconductor forming agent must be weighed with high precision.

Furthermore, since the content (mixing ratio) of the semiconducting agent is low, it is very difficult to obtain sufficient uniformity during mixing and reaction. For this purpose, PT with low resistivity at room temperature
It is difficult to obtain C, its physical properties are not uniform, and its quality varies.

[Means to solve the problem]

A method for manufacturing a barium titanate ceramic semiconductor according to the present invention is a method for manufacturing a barium titanate ceramic semiconductor by adding a semiconducting agent to a barium titanate base composition containing a Curie point transfer substance and firing the mixture. The present invention is characterized in that a 5b2o sol is used as a curing agent for the barium titanate base composition.

The amount of 5b205 sol added is 0.03 mol% to 1.
0 mol% range, 5b2o, sol is 5b20.
This means that ultrafine particles are dispersed in water. 5
The bzOs sol has a very small particle size of 0.02 μm to 0.05 μm, compared to the powder size of about 1 μm to 3 μm. The component concentration can be varied within the range of 10% to 70%. In addition, 5b205 sol has lower toxicity than 5b2o3, and since it does not require handling of powder, there is no harm caused by dust, and it is extremely easy to handle, making it a semiconducting agent that can significantly improve the working environment.

[For production]

According to the above configuration, 0, 0 added as a semiconducting agent
5bzO in 5bzOs sol from 3 mol% to 1.0 mol%
Since the particle size of s particles is extremely small, uniform mixing and reactions are possible, making it easier to manufacture semiconductors, and also allowing resistivity at room temperature to be set smaller and variations in quality to be suppressed. Therefore, it is possible to manufacture a highly versatile low resistance PTC element that can be used in circuits with small current capacity.

Further, since the sb and o5 particles are dispersed in water (for example, 5iyt% to 50tyt%), they can be weighed in large amounts, so that the error in weighing the semiconducting agent can be significantly reduced. For example, when the wt% of 5b205 particles in water is 5 wt%, it is possible to weigh 20 times the amount conventionally. For this reason, the control amount of 5bzOs particles can be controlled up to five decimal places (conventionally, the limit was up to three decimal places).

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 and 2.

This example describes a method for producing a barium titanate ceramic semiconductor, which comprises adding a semiconducting agent to a barium titanate base composition containing a Curie point transfer substance and firing the mixture. 0.03 mol% to 1.0 mol% of antimony pentoxide (5
It discloses how the resistivity at room temperature changes depending on the amount of 5b205 sol added when using 5b205 sol.

In this example, strontium carbonate (SrCO3
0.03 mol% to 1.0 mol% of antimony pentoxide (5bzOs) sol is blended into a barium titanate-based composition containing a Curie point transfer substance such as Manganese carbonate (MnC03
), and silicon dioxide (5i
Oz) etc. are blended.

That is, a semiconducting agent (antimony pentoxide sol) is added to a barium titanate base composition, and this mixture is wet-mixed in a ball mill for 6 to 48 hours, filtered, and dried, and then heated to a temperature of 1000"C to 1300 Calcinate for 1 to 3 hours at °C. Add a raw material composition that releases gas and decompose to the calcined mixture, and use a ball mill for 6 to 4 hours.
Wet mix and simultaneously mill for 8 hours. The above-mentioned pulverized material is mixed in an aqueous solution containing a binder, the slurry is dried and granulated with a spray dryer, the granules are molded, and the molded product is heated at 1300 to 1400°C for 0 to 10 hours. , held and fired to obtain a barium titanate porcelain semiconductor.

The present invention will be explained in more detail below based on comparative examples and examples.

First, the influence of the addition of antimony oxide (<5bz03) on the electrical properties of barium titanate ceramic semiconductors will be explained below based on [Comparative Example 1] to [Comparative Example 3].

[Comparative Example 1] Anhydrous barium carbonate (BaCO3, manufactured by Sakai Chemical Co., Ltd.)
680, 72 g, high purity titanium dioxide 7 (TiO2,
Toho Titanium Co., Ltd.) 290.12 g, anhydrous strontium carbonate (5rCO:+, Honjo Chemical Co., Ltd.)
26.80 g, manganese carbonate (MnC0a, Wako Pure Chemical Industries, Ltd., 99.9% reagent) 0.2087 g, silicon dioxide (5iOz, Rare Metallic Co., Ltd., 99.9% reagent) 1.0908 g, and antimony oxide (Sb2
03, Rare Metallic Co., Ltd., 99.9% reagent) 1.0
584g 5! Put it in a large capacity ball mill and add 3 ounces of water to it.
．． 5! and 40 nylon-coated iron balls with a diameter of 25 mm were added, and after wet grinding and mixing for 24 hours,
Filtered and the mixture was dried at 130'C.

The dry mixture is molded into a mold C6.5mm (diameter)
x45mm (height)] and molded under a pressure of 150 kg/Ca, and the molded product was placed in an electric furnace and heated at 180°.
The mixture was heated at a temperature increase rate of C/h and calcined at ]15°C for 2 hours.

The calcined molded product was placed in a vibrating ball mill, and the amount of water was 0.7! and 20 nylon-coated iron balls with a diameter of 15 mm.
15 wt% polyvinyl alcohol (PVA) aqueous solution was added to this, stirred for 2 hours, and the slurry was sprayed with a spray dryer. It was dried and granulated into granules with a diameter of about 50 μm.

The granules were molded into a mold (12.5 mm (diameter) x 35
mm (height)] and molded under a pressure of 1 ton/c+fl, and the molded product was fired under the following conditions.

Temperature range: Temperature rising or falling conditions room temperature to 80°C
0°C 145°C/hour Temperature increase 800°C Hold for 2 hours 800°C to 1360°C 150°C/hour Temperature increase 136
0°C 1,5 hour hold 1360°C to 1000°C 360°C/hour temperature drop 10
00'C~500°C245°C/hour temperature drop 550'
After cooling to room temperature, an ohmic silver electrode (manufactured by Deguza Corporation) was applied to the disc surface of the tablet-shaped molded product and baked at 580°C for 5 minutes to form an electrode. A cover electrode (manufactured by Deguza) was applied on top and baked at 560°C for an additional 5 minutes.
A barium titanate porcelain semiconductor was obtained.

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Bao, 9SsrO,+1!i) TlO2+0
．． 0005MnOz + 0.0053102〇, 0
OISb203 As a result of measuring the temperature change in the resistance of this sample, the temperature at which a region exhibiting a positive temperature coefficient of resistance occurs (Curie point) is 103
°C, and the rise width of the resistance was four digits. At this time, the resistivity at room temperature was 19.50 Ω·cm.

[Comparative Example 2] Anhydrous barium carbonate (BaC0:+) 680.95 g
, high purity titanium oxide (TiO□) 290.20g,
Anhydrous strontium carbonate (5rC03) 26.81
g, carbonic acid'? 7 guns (MnCO:+) 0.2088
g, silicon oxide (5iOz) 1.0911g, and Andemo7 oxide (5bz(L+) 0.7409
A barium titanate ceramic semiconductor sample was obtained in the same manner as in Comparative Example 1 above, except that g was used.

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Bao, qssro, os) TiO3+0.00
05MnO□4-0.005SiOz〇, 0O07S
bz(L+ As a result of measuring the temperature change in the resistance of this sample, the temperature (Curie point) at which a region exhibiting a positive temperature coefficient of resistance occurs is 115
°C, the width of the resistance rise was three orders of magnitude. At this time, the resistivity at room temperature was 3.4 Ω·cm.

[Comparative Example 3] 680.37 g of anhydrous barium carbonate (BaC0a),
High purity titanium oxide (Ti0z) 289.96 g
, anhydrous strontium carbonate (5rCO3) 26.79
g, manganese carbonate (MnCOa) 0.2086g
A sample of barium titanate porcelain was obtained in the same manner as in Comparative Example 1 above, except that 1.0902 g of silicon dioxide (5iOz) and 1.5868 g of antimony oxide (<5bzO3) were used.

The composition of the raw materials for this barium titanate porcelain is as follows.

(Bao, 9SsrO, os) TiO3+0.000
5MnOz+0.005SiOz+0.0015sbz
o3 This sample became an insulator and did not become a semiconductor, making it impossible to measure the above physical properties.

From the above [Comparative Example 1] to [Comparative Example 3], it can be seen that as long as the amount of antimony oxide (5bz03) added is within a predetermined range, it does not adversely affect the electrical properties of the barium titanate ceramic semiconductor. In other words, antimony oxide (5b
When the amount of zO3) added is outside the above range, the rising width of the resistance of the barium titanate ceramic semiconductor becomes smaller and it becomes an insulator in proportion to the amount added. If the amount of antimony oxide (5b203) added is larger than the above range, the barium titanate ceramic semiconductor may become an insulator.

By the way, antimony oxide (5bzO3) in the raw material composition of barium titanate ceramic semiconductor is partially converted into antimony pentoxide (Sb20) during the heating process as a single substance.
5) Metastases. Therefore, as a semiconducting agent, antimony pentoxide (5b
The case where zO5) sol is blended will be described in detail below based on [Example 1] to [Example 4]. In addition, in [Example 1] to [Example 4], 5b
The blending composition of raw materials other than 20S sol is as described above [Comparative Example 1]
The conditions were the same as those in Comparative Example 3.

[Example 1] Anhydrous barium carbonate (BaCO3 + Sakai Chemical Co., Ltd. BW-[,
) 680.651 g, high purity titanium dioxide (TiO□
, manufactured by Toho Titanium Co., Ltd.) 290.076 g, anhydrous strontium carbonate (5rCO, manufactured by Honjo Chemical Co., Ltd.) 26.
798 g, manganese carbonate (MnC0,, manufactured by Wako Pure Chemical Industries, Ltd., 99.9% reagent) 0.2086 g, silicon dioxide (SiO□, manufactured by Rare Metallic Co., Ltd., 99.9% reagent)
1.0906g, and antimony pentoxide sol (5
b20s, manufactured by Nissan Chemical Industries, Ltd., A-15504ht
%) 2.4466 g to 5! Put it in a ball mill with a capacity of 3.51 liters of water! , and 40 nylon-coated iron balls with a diameter of 25 mm were added, wet-milled and mixed for 24 hours, filtered, and the mixture was dried at 130"C. The dry mixture was placed in a mold (6 ,5
mm (diameter) x 45mm (height)], 150
molded under a pressure of kg/c++I, placed the molded product in an electric furnace, and heated at a temperature increase rate of 180 ° C / hour,
It was calcined at 1150°C for 2 hours.

The calcined molded product was placed in a vibrating ball mill, and the amount of water was 0.7! and 20 nylon-coated iron balls with a diameter of 15 mm.
and 15 similar iron balls with a diameter of 10 mm.
After wet grinding for 6 hours, 150 g of 15 wt% polyvinyl alcohol (PVA) aqueous solution was added and stirred for 2 hours and 3 hours, and the slurry was spray-dried with a spray dryer to form granules with a diameter of about 50 μm. did. The granules were put into a mold (12.5 mm (diameter) x 35 mm' (height)) and molded under a pressure of 1 ton/c+fl, and the molded product was fired under the following conditions.

Temperature range Room temperature to 800°C 800°C 800''C - 1360'C 1360°C Temperature raising or lowering conditions: 14mm °C/hour temperature increase, 2 hour hold 150°C/hour temperature rise, 1.5 hour hold 1360°C ~ 1000°C 360°C/hour temperature drop 10
00°C to 500°C245°C/hour Temperature drop 550″C
Completion of temperature control After cooling to room temperature, an ohmic silver electrode (manufactured by Degussa) is applied to the disc surface of the tablet-shaped molded product and baked at 580°C for 5 minutes to form an electrode.A cover is placed on the electrode. An electrode (manufactured by Degussa) was applied and baked at 560°C for 5 minutes to obtain a barium titanate ceramic semiconductor.

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Bao, qsSro, os) TiO3+0.0
005MnOz+0.005SiOz+0.001Sb
205 As a result of measuring the temperature change in the resistance of this sample, the temperature at which a region exhibiting a positive temperature coefficient of resistance occurs (Curie point) is 111
°C, and the rise 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 (BaC(L+) 680.89 g
, high purity titanium dioxide (Ti0z) 290.17g
, anhydrous strontium carbonate (5rCO3) 26.80
g1 Manganese carbonate (MnCO:+) 0.208
g, silicon dioxide (5iOz) 1.091g, and antimony pentoxide sol (5bzO5) 1°712g
A barium titanate ceramic semiconductor sample was obtained in the same manner as in Example 1 above, except that .

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Bao, 95SrO, os) TiO3+0.00
05) In02+0.005Si0200,0O07S
bZO5 As a result of measuring the temperature change in the resistance of this sample, the temperature (Curie point) at which a region exhibiting a positive temperature coefficient of resistance occurs is 115.
°C, the rise width of the resistance was three orders of magnitude. At this time, the resistivity at room temperature was 44.54 Ω·cm.

(Example 3) Anhydrous barium carbonate (BaC03) 680.41 g
, high purity titanium dioxide (Ti07) 289.97g,
Anhydrous strontium carbonate (5rCo3) 26.78
Barium titanate porcelain was prepared in the same manner as in Example 1 above, except that 0.208 g of manganese carbonate (MnCO3), 1090 g of silicon dioxide (5iOz), and 3.179 g of antimony pentoxide sol (5b205) were used. A semiconductor sample was obtained.

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Baa, q5sro, +Is) TiO: + +
0.0005Mn02+0.005SiOz-+-o,
oot3sbzo,.

As a result of measuring the temperature change in the resistance of this sample, the temperature at which a region exhibiting a positive temperature coefficient of resistance occurs (Curie point) is 110
°C, the rise width of the resistance was two orders of magnitude. At this time, the resistivity at room temperature was 5.42 Ω·cm.

[Example 4] Anhydrous barium carbonate (BaC03) 680.25 g,
High purity titanium dioxide (TiO□) 289.90g, anhydrous strontium carbonate (5rCOz) 26.78
g, manganese carbonate (MnC(L+) 0.2081
1.090 g of silicon oxide (5iOz) and antimony pentoxide sol (sb2o.

) A sample of barium titanate ceramic semiconductor was obtained in the same manner as in Example 1 above, except that 3.667 g was used.

The composition of the raw materials for this barium titanate ceramic semiconductor is as follows.

(Baa, q, Sro, os) TiO3+0. O
O05MnOz +0.005SiOz+O,0O15
Sb205 As a result of measuring the temperature change in the resistance of this sample, the temperature (Leuly point) at which a region exhibiting a positive temperature coefficient of resistance occurs is 105.
°C, the rise width of the resistance was in the single digit range. 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 as shown in Table 1. As is clear from Table 1, by using antimony pentoxide (5bzOs) sol for the barium titanate base composition as a semiconducting agent (characteristics shown by the broken line in FIG. 2),
The resistivity at room temperature can be made much smaller with a smaller amount than when antimony oxide (Sb20) powder is used (characteristics shown by the solid line in FIG. 2) (see Comparative Examples 1 and 2). In addition, the dependence of the amount of 5b205 added in the barium titanate ceramic semiconductor ([Example]) or [
The characteristics corresponding to each sample of Example 4] are as shown in FIG. That is, as shown in FIG. 1, the amount of 5b205 added to the barium titanate ceramic semiconductor is 0.03 mol%.
or greater than 0.15 mol %, the resistivity (specific resistance) at room temperature becomes significantly large. Therefore, the amount of 5b205 added is preferably 0.
It can be seen that the amount is in the range of 0.03 mol% to 0.15 mol%.

Here, methods for measuring various physical properties of samples of various barium titanate ceramic semiconductors having different raw material compositions will be described below.

(1) Measurement of Curie point Attach the sample of barium titanate porcelain semiconductor to the sample holder for measurement, and place it in the measurement tank (MINI-3UBZEROM
G-810P (manufactured by Nisspec ■) and measured the change in electrical resistance of the sample against temperature changes from -50°C to ~90°C using a DC resistance meter (Multimeter 3).
478A (manufactured by HP).

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

(2) Measurement of room temperature resistivity A barium titanate porcelain semiconductor sample was placed in a measurement tank at 25°C using a DC resistance meter (multimeter 3478AY).
The electrical resistance value was measured using a commercially available product (manufactured by HP).

In preparing a barium titanate porcelain semiconductor sample, the size (diameter and thickness) of the sample was measured before applying the electrode, and the specific resistance (ρ) was calculated using the following formula, and this was taken as the resistivity.

ρ-R-S/l ρ: Specific resistance (resistivity) [Ω・cm) R: Measured value of electrical resistance [Ω] S: Area of electrode [C] t: Thickness of sample (cm) (3 ) Measurement of rise width of resistivity Temperature change of Curie point measurement (from -50°C to 190°C)
Measurement of the change in electrical resistance of the sample for C) was further carried out in two steps.
Continue until the temperature exceeds 00'C, and in the resistivity-temperature plot, compare the resistivity at the sudden rise in electrical resistance at the Curie point with the resistivity at 200°C, and calculate the magnitude of that order of magnitude. The logarithmic ratio was taken as the rising width of resistivity.

In addition, since the barium titanate ceramic semiconductor according to the present invention 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 for a temperature fuse switching power supply. In addition to the above, the barium titanate ceramic semiconductor according to the present invention can be applied to electrolytic capacitor protection circuits, color TV automatic degaussing devices, motor starting devices for automobiles, overheat prevention devices for electronic equipment, delay elements, timers, liquid level gauges, etc. Can be used for non-contact switches, relay contact protection devices, etc.

(Hereinafter in the margins) Table 1 (hereinafter in the margins) [Effects of the invention] The method for producing a barium titanate ceramic semiconductor according to the present invention uses 0.03 mol% of the barium titanate base composition as a semiconducting agent. It has a structure in which ~1.0 mol % of sb, o5 sol is added.

Therefore, 0.03 mol%~ added as a semiconducting agent
The 5b205 particles in the 1.0 mol% 5b205 sol have a very small particle size, which allows uniform mixing and reaction, making semiconductor formation easier and uniform, and with a lower resistivity at room temperature. It is a highly versatile low-resistance product that can be used in circuits with small current capacity because it can be used in circuits with small current capacity. P.T.
A C element can be manufactured.

Furthermore, since the 5b209 particles are dispersed in water, they can be weighed in large amounts, so that the error in weighing the semiconducting agent is significantly reduced. In addition, the control amount of sb and o5 particles is 5 decimal points.
digits (previously the limit was up to three decimal places).

Furthermore, 5bzOs sol can be used with 5bz03 powder or 5b20
．． The raw material cost is much cheaper than powder (2 digits to 3 digits)
This makes it possible to reduce the overall cost, as well as being less toxic than 5B2O powder, and since there is no need to handle powder, there is no harm caused by dust, and it is extremely easy to handle, making it easier to work in the work environment. This also has the effect of making a significant improvement.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is an explanatory diagram showing the dependence of the resistivity of the barium titanate ceramic semiconductor according to the present invention on the amount of antimony pentoxide sol added. Figure 2 shows the dependence of the resistivity of the barium titanate ceramic semiconductor according to the present invention on the amount of sb added, and the addition of 5bz as a semiconductor agent.
FIG. 3 is an explanatory diagram showing the dependence of specific resistance on the amount of sb added when O3 powder is used.

Claims (1)

[Claims] 1. In a method for producing a barium titanate ceramic semiconductor by adding a semiconducting agent to a barium titanate base composition containing a Curie point transfer substance and firing the mixture, as the semiconducting agent,
0.03 mol% based on barium titanate base composition
A method for producing a barium titanate ceramic semiconductor, characterized in that ~1.0 mol% of Sb_2O_5 sol is used.