JP2613327B2 - Barium titanate-based porcelain semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barium titanate-based ceramic semiconductor having a positive temperature coefficient of resistance at a temperature equal to or higher than the Curie point, a low room temperature resistivity, and a high withstand voltage and excellent PTC characteristics. Things.

[0002]

2. Description of the Related Art Barium titanate is an insulator having a high specific resistance of 10 ¹⁰ Ω · cm or more, and bismuth, niobium, tungsten, tantalum, antimony, or a rare earth element is added to barium titanate. It has been conventionally known that the addition thereof results in a semiconductor porcelain having a specific resistance of 10 ⁶ Ω · cm or less. Furthermore, for example, JP-A-53-59888 discloses that a barium titanate-based porcelain semiconductor composition containing a rare earth element, tantalum, niobium, or antimony is added with silicon dioxide and fired in the presence of oxygen. It describes that the electrical properties as a porcelain semiconductor composition are improved.

[0003]

However, conventional barium titanate-based porcelain semiconductors have a positive temperature coefficient of resistance at a temperature above the Curie point, have few elements having a low resistivity at room temperature, and have a high withstand voltage. Almost no such physical properties have been obtained.

For this reason, there is a problem that a conventional PTC element cannot be used as an element requiring a high withstand voltage in a circuit having a small current capacity.

[0005]

According to the present invention, there is provided a barium titanate-based ceramic semiconductor comprising: a barium titanate-based ceramic composition containing a Curie point transfer substance; 0.07 ~
It is characterized in that it contains 0.17 mol% of antimony pentoxide as a semiconducting agent and contains 0.01 to 0.5 mol% of boron nitride.

[0006]

As described above, by incorporating antimony pentoxide in the range of 0.07 to 0.17 mol% with respect to the barium titanate-based substrate composition as a semiconducting agent, a semiconductor can be easily formed, and By adding boron nitride in the range of 0.01 to 0.5 mol% to the barium titanate-based substrate composition, the resistivity at room temperature is small without impairing the semiconductor formation by antimony pentoxide, In addition, a barium titanate-based ceramic semiconductor having a high withstand voltage can be obtained.

[0007]

EXAMPLE A barium titanate-based ceramic semiconductor obtained by adding a semiconducting agent to a barium titanate-based substrate composition containing a Curie point transfer substance and firing the same is particularly preferable for antimony pentoxide (Sb ₂ O ₅ ). Was used as a semiconducting agent, and an evaluation test for the resistivity and the withstand voltage at room temperature when boron nitride (BN) was further added was performed under the following conditions.

That is, strontium carbonate (SrCO ₃ ) is used as a Curie point transfer substance, manganese carbonate is used as a mineralizer, and silicon dioxide is used as a voltage-dependent stabilizer.

[0009] After the prescribed blending, the mixture is wet-mixed in an automatic mortar for 1 to 24 hours in the presence of ethanol (special grade reagent), dried, and then calcined at 1000 to 1400 ° C for 1 to 3 hours. . The calcined compound is crushed, and PVA (polyvinyl alcohol) 2-8 in an automatic mortar.
A wt% aqueous solution is added, mixed for 1 to 6 hours, dried and pulverized sufficiently. After the powder thus obtained is molded in a disc-shaped molding machine, the molded product is placed in the range of 1300 to 1400
Hold at 0 ° C. for 0 to 10 hours and bake. As a result, a barium titanate-based porcelain semiconductor is obtained, and the Curie point, the room temperature resistivity, the rising width of the resistance, and the DC withstand voltage are measured using this sample.

Hereinafter, antimony pentoxide (Sb ₂ O ₅ ) is added to the barium titanate-based substrate composition in an amount of 0.07 to 0.20.
Mol%, and boron nitride (BN)
Some of the test results are described together with more detailed compounding ratios and production conditions from the results obtained by changing the respective ranges in the range of ~ 0.50 mol%.

Example 1 Anhydrous barium carbonate (BaCO)
₃ , 68.03 g of high purity product manufactured by Nippon Chemical Industry Co., Ltd., 28.99 g of high purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.)
g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co.) 2.68 g, manganese carbonate (MnCO ₃ , 99.9% manufactured by Wako Pure Chemical Industries) 0.0209 g, silicon dioxide (SiO 2)
₂ , Toshiba Ceramics US-85) 0.1090 g,
Antimony pentoxide (Sb ₂ O ₅ , 9 manufactured by Rare Metallic)
0.1644 g of 9.9%) and 0.0045 g of boron nitride (BN, a special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) were blended.

The above composition was placed in an alumina mortar having an inner diameter of 200 mm, and wet-blended in an automatic mortar for 3 hours in the presence of ethanol (special grade reagent).
Dried at 0 ° C. Then, the dry mixture is 90 mm
× 90mm alumina crucible (Mitsubishi Mining Cement Co., Ltd.,
DFA-PS99).
At a heating rate of 0 ° C / h to 1150 ° C,
Calcination was performed at 150 ° C. for 2 hours.

The calcined product was pulverized in a mortar, stirred in an automatic mortar with about 100 cc of a 2 wt% PVA aqueous solution for 3 hours, and dried at 130 ° C.

The dried product thus obtained is pulverized well in a mortar, and a powder containing PVA is molded into a molding die (with an inner diameter of 12.
(5 mm, height 35 mm), and pressure-molded at a pressure of 1 ton / cm ² , and the molded product was fired under the following conditions.

[Temperature range] [Conditions for raising or lowering the temperature] Room temperature to 800 ° C. 145 ° C./h Temperature increase 800 ° C. Hold for 2 hours 800 to 1360 ° C. 150 ° C./h Temperature increase 1360 ° C. Hold for 15 minutes 1360 to 1000 Temperature drop of 360 ° C / h 1000-550 ° C Temperature drop of 245 ° C / h 550 ° C Termination of temperature control After the fired sample is cooled to room temperature, an ohmic silver electrode (Degussa 5) and apply 5
The electrode was formed by baking at 80 ° C. for 5 minutes. Further, a cover electrode (made by Degussa Co., Ltd.) is applied on the electrode,
For 5 minutes to obtain a barium titanate-based ceramic semiconductor sample.

The composition of the raw materials of the barium titanate-based ceramic semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0014Sb ₂ O ₅ + 0.0005BN The Curie point of this sample is 108 ° C., and the rise width of the resistance is 2.4 digits. Was. The resistivity of the sample at room temperature was 5.68 Ω · cm. As a result of measuring current-voltage characteristics, the DC withstand voltage was 24.4 V / mm.

Example 2 Anhydrous barium carbonate (BaCO)
₃ , 68.03 g of high purity product manufactured by Nippon Chemical Industry Co., Ltd., 28.99 g of high purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.)
g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co.) 2.68 g, manganese carbonate (MnCO ₃ , 99.9% manufactured by Wako Pure Chemical Industries) 0.0209 g, silicon dioxide (SiO 2)
₂ , Toshiba Ceramics US-85) 0.1090 g,
Antimony pentoxide (Sb ₂ O ₅ , 9 manufactured by Rare Metallic Co., Ltd.)
(0.199%), 0.1644 g, and 0.0090 g of boron nitride (BN, special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) were blended.

With the above composition, a barium titanate-based ceramic semiconductor was produced in the same manner as in Example 1.

The composition of the raw materials for the barium titanate-based porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0014Sb ₂ O ₅ + 0.001BN An electrode was formed on the fired sample in the same manner as in Example 1, and the electrical characteristics were measured.

The Curie point of this sample is 107 ° C.
The rise width of the resistance was 2.5 digits (measured up to 180 ° C.). The resistivity of the sample at room temperature is 6.75Ω ·
cm. As a result of measuring the current-voltage characteristics, the DC withstand voltage was 26.2 V / mm.

Comparative Example 1 Anhydrous barium carbonate (BaCO)
₃ , 68.03 g of high purity product manufactured by Nippon Chemical Industry Co., Ltd., 28.99 g of high purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.)
g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co.) 2.68 g, manganese carbonate (MnCO ₃ , 99.9% manufactured by Wako Pure Chemical Industries) 0.0209 g, silicon dioxide (SiO 2)
₂ , Toshiba Ceramics US-85) 0.1090 g,
And 0.1761 g of antimony pentoxide (Sb ₂ O ₅ , 99.99% manufactured by Rare Metallic) was blended.

With the above composition, a barium titanate-based ceramic semiconductor was produced in the same manner as in Example 1.

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

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0015Sb ₂ O ₅ The Curie point of this sample was 105 ° C., and the rise width of the resistance was 2.3 digits. The resistivity of the sample at room temperature was 4.84 Ω · cm. As a result of measuring the current-voltage characteristics, the DC withstand voltage was 13.0 V / mm.

[Comparative Example 2] Anhydrous barium carbonate (BaCO
₃ , 68.04 g of high purity product manufactured by Nippon Chemical Industry Co., Ltd., 29.00 g of high purity titanium dioxide (TiO ₂ , manufactured by Toho Titanium Co., Ltd.)
g, anhydrous strontium carbonate (SrCO ₃ , manufactured by Honjo Chemical Co.) 2.70 g, manganese carbonate (MnCO ₃ , 99.9% manufactured by Wako Pure Chemical Industries) 0.0209 g, silicon dioxide (SiO 2)
₂ , Toshiba Ceramics US-85) 0.1090 g,
Antimony oxide (Sb ₂ O ₃ , manufactured by Rare Metallic Co., Ltd., 99.
0.158 g and tantalum pentoxide (Ta)
0.0481 g of ₂ O ₅ (99.9%, manufactured by Rare Metallic Co., Ltd.).

Here, antimony oxide and tantalum pentoxide were used as the semiconducting agent.

With the above composition, a barium titanate-based ceramic semiconductor was produced in the same manner as in Example 1.

The composition of the raw materials for the barium titanate-based porcelain semiconductor is as follows.

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.001Sb ₂ O ₃ + 0.0003Ta ₂ O ₅ An electrode was formed on the fired sample in the same manner as in Example 1, and the electrical characteristics were measured. It was measured.

The Curie point of this sample is 105 ° C.
The rise width of the resistance was 4.0 digits. The resistivity of the sample at room temperature was 6.22 Ω · cm. As a result of measuring the current-voltage characteristics, the DC voltage was 13.1 V / mm.

Table 1 summarizes the above results.

As is clear from Table 1, by adding antimony pentoxide to the barium titanate-based substrate composition as a semiconducting agent and further adding boron nitride, the resistivity at room temperature is reduced and the current-voltage characteristics are reduced. Can be made higher.

The higher the amount of boron nitride added, the higher the DC withstand voltage can be. However, the resistivity at room temperature increases as the amount of boron nitride increases. Therefore,
By setting the amount of boron nitride to be in the range of 0.01 to 0.50 mol%, it is possible to obtain a barium titanate-based ceramic semiconductor having a high DC withstand voltage while keeping the resistivity at room temperature small. it can.

The amount of antimony pentoxide added as a semiconducting agent is preferably in the range of 0.07 to 0.17 mol% in order to reduce the resistivity at room temperature.

As described above, by adding 0.07 to 0.17 mol% of antimony pentoxide as a semiconducting agent and adding 0.01 to 0.50 mol% of boron nitride,
A barium titanate-based ceramic semiconductor having excellent PTC characteristics having a small resistivity at room temperature and a high withstand voltage can be obtained.

Here, a method for measuring various physical properties of a sample of a barium titanate-based ceramic semiconductor will be described as follows.

(1) Measurement of Curie point A sample of a barium titanate-based porcelain semiconductor was mounted on a sample holder for measurement and mounted in a measuring tank [MINI-SUBZERO MC-810P manufactured by Tabi Espec Corporation] at -50 ° C. From 1
The change in the electrical resistance of the sample with respect to the temperature change up to 90 ° C. is measured using a DC resistance meter (Multimeter 3478A manufactured by YHP).

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

(2) Measurement of resistivity at room temperature A barium titanate-based porcelain semiconductor sample was placed in a 25 ° C. measuring tank in a DC resistance meter (multimeter 3478A YHP).
) Is used to measure the electrical resistance.

In preparing a barium titanate-based ceramic semiconductor sample, the size (diameter and thickness) of the sample before electrode coating
Is measured, and the specific resistance (ρ) is calculated by the following equation, and this is defined as the resistivity. ρ = R · S / t ρ: Specific resistance (resistivity) [Ω · cm] R: Measured value of electric resistance [Ω] S: Area of electrode [cm ² ] t: Thickness of sample [cm] (3 ) Measurement of rise width of resistivity Temperature change of Curie point measurement (from -50 ° C to 190 ° C)
The change in the electrical resistance of the sample with respect to
C., and the resistivity-temperature plot compares the resistivity at the time of a sharp rise in electrical resistance at the Curie point with the resistivity at 200 ° C., and determines the logarithmic ratio of the number of digits to the resistance. The rise width of the rate.

(4) DC withstand voltage A barium titanate-based porcelain semiconductor material is attached to a measurement holder, and a stabilized DC power supply (SEGULATED DC POWER SUPPL) is mounted.
Y GPO350-2, GPO25-5, TAKASAGO LTD), Multimeter (AD
AVANTEST). The voltage was gradually increased from 100 mV, and the current value with respect to the voltage read by a DC voltmeter was measured by a multimeter.

From the plot of the current value with respect to the voltage obtained by the measurement, the thermal runaway voltage was defined as V _BD, and this voltage was defined as the DC withstand voltage.

As described above, a barium titanate-based ceramic semiconductor having a small resistivity at room temperature and a high withstand voltage can be used as a low-resistance PTC element in a circuit having a small current capacity. Since it has relatively stable current-voltage characteristics in direct current, it can be used for applications requiring low resistance at room temperature and withstand voltage.

Further, a motor overcurrent prevention, an electrolytic capacitor protection circuit, a color television automatic degaussing device, a motor starting device for an automobile, etc., a heating prevention device for electronic equipment, a delay element, a timer, a liquid level gauge, a non-contact switch, It can be used for a relay contact protection device and the like.

[0047]

[Table 1]

[0048]

The barium titanate-based ceramic semiconductor according to the present invention is, as described above, a barium titanate-based semiconductor containing a Curie point-transferring substance in an amount of 0.07 to 0.07 with respect to the barium titanate-based substrate composition. 0.17 mol% of antimony pentoxide is contained as a semiconducting agent, and 0.01 to 0.1.
The structure includes 5 mol% of boron nitride.

Thus, a barium titanate-based ceramic semiconductor having a positive temperature coefficient of resistance at a temperature equal to or higher than the Curie point, a small resistivity at room temperature, and a high withstand voltage is obtained. For example, it has an effect that it can be used as an element having low resistance at room temperature and withstand voltage in a circuit having a small current capacity.

Claims (1)

(57) [Claims] 1. A barium titanate-based porcelain semiconductor containing a Curie point transfer substance, comprising 0.07 to 0.17 mol% of antimony pentoxide as a semiconducting agent based on a barium titanate-based substrate composition. A barium titanate-based porcelain semiconductor comprising 0.01 to 0.5 mol% of boron nitride.