JPH04343401A - Barium titanate porcelain semiconductor - Google Patents

Abstract

PURPOSE:To produce a general-purpose low-resistance PTC element applicable to a circuit of small current capacity by permitting barium titanate base component which contains PbTiO3 as Curie point moving material to contain the specific quantity of Sb2O3 as an agent to make the material semiconductive. CONSTITUTION:Sb2O3 as agent to make material semiconductive is added within a range of more than 0.11 mol% less than 0.13 mol% to titanate base component which contains PbTiO3 as Curie point moving material, and a barium titanate ceramic semiconductor is produced. Since the adding quantity of Sb2O3 is limited within the range, the barium titanate porcelain semiconductor whose room temperature resistivity is very low having positive resistance temperature coefficient whose rising width of resistivity at the temperature of the Curie point or above is wide is produced. Thus, a general-use low-resistance PTC element applicable to a circuit of small current capacity is produced.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a barium titanate-based ceramic semiconductor which has a positive temperature coefficient of resistance at temperatures above the Curie point and has excellent PTC characteristics due to extremely low room temperature resistivity. be.

0002

[Prior Art] By adding oxides of rare earth elements, tantalum, bismuth, tungsten, silver, antimony, etc. to barium titanate-based porcelain, a positive temperature coefficient of resistance (
It has been known for a long time that a ceramic semiconductor having PTC characteristics can be obtained. Also, for example, JP-A-53-5988
No. 8, etc., discloses that silicon dioxide is added to a barium titanate-based ceramic semiconductor composition containing rare earth elements, tantalum, niobium, or antimony, and the electrical properties of the ceramic semiconductor composition are determined by firing in the presence of oxygen. It is stated that this improves the

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional barium titanate-based ceramic semiconductor has a small rise in resistivity at temperatures above the Curie point, and
Since the resistivity at room temperature is high, it is difficult to obtain a versatile low-resistance PTC element that can be used in a circuit with a small current capacity.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention provides PbTiO3 as a Curie point transfer substance.
The barium titanate base composition contains Sb2O3 as a semiconductor agent in a range of more than 0.11 mol% and less than 0.13 mol%.

[0005]

[Action] As mentioned above, PbT is used as a Curie point transfer substance.
Sb2 containing iO3 and in a range of more than 0.11 mol% and less than 0.13 mol% as a semiconducting agent
By adding O3, a barium titanate-based ceramic semiconductor can be obtained which has a very small resistivity at room temperature and a positive temperature coefficient of resistance with a large rise in resistivity at temperatures above the Curie point. As a result, it is possible to obtain a low-resistance PTC element that can be used in a circuit with a small current capacity and has excellent versatility.

[0006]

【Example】

[Example 1] Anhydrous barium carbonate (BaCO3, high-purity product manufactured by Sakai Chemical Co., Ltd.), high-purity titanium dioxide (TiO2, manufactured by Toho Titanium Co., Ltd.), lead oxide (PbO, Resurge No. 1 manufactured by Nippon Kagaku Co., Ltd.), manganese carbonate ( MnCO3, manufactured by Wako Pure Chemical Industries, Ltd., 99.9%), silicon dioxide (SiO2), antimony oxide (Sb2 O3, manufactured by Rare Metallic Co., Ltd.,
99.9%) was used as a starting material and blended to have the following composition.

(Ba0.95Pb0.05)TiO3+0.
0005MnO2+0.005SiO2 +0.001
2Sb2O3 That is, as shown in the above formula, 5 mol% of PbTiO3 as a Curie point transfer substance, 0.05 mol% of MnO2 as a mineralizer, and 0.5 mol% of silicon dioxide as an abnormal grain growth inhibitor. and 0.12 mol% of Sb2O3 as a semiconducting agent.

[0008] One kilogram of the raw materials after blending was put into a nylon ball mill having an internal volume of 5 liters, together with 40 agate balls (diameter 25 mm) and 3 liters of ion-exchanged water, and mixed for 24 hours. After the mixing was completed, the mixture was filtered and dried at 130° C. for 16 hours. Then, the dry mixture was cut into a 45 mm inner diameter
, filled into a mold with a height of 65 mm, 150 kg/c
After pressure molding at a pressure of m2, the temperature was raised to 1150°C at a rate of 180°C/min, and calcined at 1150°C for 2 hours.

[0009] Then, after crushing the calcined product in a mortar,
The powder was classified through a 9-mesh sieve, put into a mold (inner diameter 12.5 mm, height 35 mm), and 1 ton/h
Pressure molding was performed at a pressure of cm2, and the molded product was fired under the following conditions. [Temperature range] [Temperature raising or lowering conditions] Room temperature to 800℃
Temperature increase 800℃ at 145℃/h
Hold for 2 hours 800-1360℃
Temperature increase 1360℃ at 150℃/h
Hold for 15 minutes 13
60~1000℃ 360℃/h Temperature drop 1000~550℃ 245℃/h
Temperature drop of 550℃
After the sample after completion of temperature control firing was cooled to room temperature, an ohmic silver electrode (manufactured by Degussa) was applied to the disk surface of the tablet-shaped molded product and baked at 580° C. for 5 minutes to form an electrode. Furthermore, a cover electrode (manufactured by Degussa) was applied on the electrode, and baked at 560°C for 5 minutes.
A sample of barium titanate ceramic semiconductor was obtained.

[0010] The Curie point of this sample is 148°C,
The rise width of the resistance was 3.8 orders of magnitude. Further, the resistivity of the sample at room temperature was 4.6 Ω·cm. The measurement results of the resistance-temperature characteristics are shown by the curve a in FIG.

[Example 2] Anhydrous barium carbonate (BaCO
3, high-purity product manufactured by Sakai Chemical Co., Ltd.), high-purity titanium dioxide (T
iO2, manufactured by Toho Titanium Co., Ltd.), lead oxide (PbO, Resurge No. 1 manufactured by Nippon Kagaku Co., Ltd.), manganese carbonate (MnCO3)
, manufactured by Wako Pure Chemical Industries, Ltd., 99.9%), silicon dioxide (Si
O2) and antimony oxide (Sb2O3, manufactured by Rare Metallic Co., Ltd., 99.9%) were blended as starting materials to have the following composition.

(Ba0.95Pb0.05)TiO3+0.
0005MnO2+0.005SiO2 +0.001
25Sb2O3 A barium titanate-based ceramic semiconductor was produced using the above-mentioned formulation and the same operations as in Example 1. Electrodes were formed on the fired sample in the same manner as in Example 1, and the electrical properties were measured.

[0013] The Curie point of this sample is 145°C,
The rise width of the resistance was 3.5 orders of magnitude. Further, the resistivity of the sample at room temperature was 3.7 Ω·cm. Resistance-
The measurement results of the temperature characteristics are shown by the curve b in FIG.

[Comparative Example 1] Anhydrous barium carbonate (BaCO
3, high-purity product manufactured by Sakai Chemical Co., Ltd.), high-purity titanium dioxide (T
iO2, manufactured by Toho Titanium Co., Ltd.), lead oxide (PbO, Resurge No. 1 manufactured by Nippon Kagaku Co., Ltd.), manganese carbonate (MnCO3)
, manufactured by Wako Pure Chemical Industries, Ltd., 99.9%), silicon dioxide (Si
O2) and antimony oxide (Sb2O3, manufactured by Rare Metallic Co., Ltd., 99.9%) were blended as starting materials to have the following composition.

(Ba0.95Pb0.05)TiO3+
0.0005MnO2+0.005SiO2 +0.0
011Sb2O3 A barium titanate-based ceramic semiconductor was produced using the above-mentioned formulation and the same operations as in Example 1. Electrodes were formed on the fired sample in the same manner as in Example 1, and the electrical properties were measured.

[0016] The Curie point of this sample is 145°C,
The resistance rise width was 3.2 digits. Further, the resistivity of the sample at room temperature was 12.5 Ω·cm. The measurement results of the resistance-temperature characteristics are shown by the curve c in FIG.

[Comparative Example 2] Anhydrous barium carbonate (BaCO
3, high-purity product manufactured by Sakai Chemical Co., Ltd.), high-purity titanium dioxide (T
iO2, manufactured by Toho Titanium Co., Ltd.), lead oxide (PbO, Resurge No. 1 manufactured by Nippon Kagaku Co., Ltd.), manganese carbonate (MnCO3)
, manufactured by Wako Pure Chemical Industries, Ltd., 99.9%), silicon dioxide (Si
O2) and antimony oxide (Sb2O3, manufactured by Rare Metallic Co., Ltd., 99.9%) were blended as starting materials to have the following composition.

(Ba0.95Pb0.05)TiO3+
0.0005MnO2+0.005SiO2 +0.0
013Sb2O3 A barium titanate-based ceramic semiconductor was produced using the above-mentioned formulation and the same operations as in Example 1. Electrodes were formed on the fired sample in the same manner as in Example 1, and the electrical properties were measured.

The resistivity of this sample at room temperature is 3400
It was Ωcm.

Table 1 summarizes the results of Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

[0021]

[Table 1]

As is clear from Table 1, by adding Sb2O3 to the barium titanate base composition as a semiconductor agent, the resistivity at room temperature can be made extremely low. However, if the amount of Sb2O3 added is less than 0.11 mol%, or 0.13
If the amount is more than mol %, the resistivity at room temperature will increase. Therefore, Sb2 as a semiconducting agent
By setting the amount of O3 added in a range of more than 0.11 mol% and less than 0.13 mol% in a barium titanate ceramic semiconductor containing PbTiO3 as a Curie point transfer substance, the room temperature resistivity can be extremely small. ,
Moreover, it has been revealed that a barium titanate-based ceramic semiconductor having excellent PTC characteristics with a wide rise in resistivity can be obtained.

The method for measuring the physical properties of a barium titanate-based ceramic semiconductor sample will be described below.

(1) Measurement of Curie point A barium titanate ceramic semiconductor sample is attached to a sample holder for measurement, and placed in a measurement tank [MINI-SUBZERO].
MC-810P manufactured by Tabai Espec Co., Ltd.], and the change in electrical resistance of the sample with respect to temperature changes from -50°C to 190°C is measured using a DC resistance meter (Multimeter 3478A manufactured by YHP). Based on the electrical resistance-temperature plot obtained by measurement, the temperature at which the resistance value becomes twice the resistance value at room temperature is defined as the Curie point.

(2) Measurement of room temperature resistivity A barium titanate ceramic semiconductor sample was placed in a measurement tank at 25°C using a DC resistance meter (Multimeter 3478A Y).
The electrical resistance is measured using a 100% HP (manufactured by HP) product. When preparing a barium titanate ceramic semiconductor sample, measure the size (diameter and thickness) of the sample before applying the electrode, calculate the specific resistance (ρ) using the following formula, and use this as the resistivity. . ρ=R・S/t ρ: Specific resistance (resistivity) [Ω・cm]R
: Measured value of electrical resistance [Ω] S: Area of electrode [cm2] t:
Sample thickness [cm] (3)
Measurement of rise width of resistivity Temperature change in measurement of Curie point (-50℃ to 190℃)
Measurement of the change in electrical resistance of the sample was further carried out for 200
℃, and in the resistivity-temperature plot, compare the resistivity when the electrical resistance suddenly rises at the Curie point and the resistivity at 200℃, and calculate the logarithmic ratio of that order of magnitude as the resistance. This is the rise width of the rate.

It should be noted that the barium titanate-based ceramic semiconductor of each of the embodiments according to the present invention manufactured as described above has a low resistivity at room temperature, so it can be used as a low resistance PTC element in a circuit with a small capacitance. For example, it can be used as a thermal fuse, a comparator for a switching power supply, etc. Furthermore, since the Curie point is around 140°C due to 5 mol % of PbTiO3 added as a Curie point shifting substance, it can also be applied as a heater element with a switching temperature around 140°C. In addition to the above, there are protection circuits for electrolytic capacitors,
It can be used in automatic color TV degaussing devices, motor starting devices for automobiles, heating prevention devices for electronic equipment, delay elements, timers, liquid level gauges, non-contact switches, relay contact protection devices, etc.

[0027]

Effects of the Invention As described above, the barium titanate-based ceramic semiconductor according to the present invention has P as a Curie point moving substance.
bTiO3, more than 0.11 mol% and less than 0.13 mol% S based on barium titanate based substrate composition
This structure includes b2 O3 as a semiconductor agent.

[0028] As a result, a barium titanate-based ceramic semiconductor having a positive temperature coefficient of resistance at temperatures above the Curie point, a smaller resistivity at room temperature, and a wide rise in resistivity can be produced. This has the effect that it is possible to obtain a low-resistance PTC element that can be used in a circuit with a small current capacity and has excellent versatility.

[Brief explanation of the drawing]

FIG. 1 is a graph showing measurement results of resistivity temperature characteristics of a barium titanate-based ceramic semiconductor according to the present invention.

Claims (1)

[Claims] Claim 1: PbTiO3 as a Curie point transfer substance
A barium titanate-based ceramic semiconductor, characterized in that the barium titanate-based substrate composition contains Sb2O3 as a semiconductor agent in a range of more than 0.11 mol% and less than 0.13 mol%.