JP2839932B2 - Method for producing barium titanate porcelain semiconductor - Google Patents

Description

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

[Prior art] Positive temperature coefficient of resistance (PTC characteristic) is obtained by adding oxides such as lanthanum, tantalum, cellium, yttrium, bismuth, tungsten, silver, samarium, and dysprosium to barium titanate-based porcelain. Obtaining a porcelain semiconductor having the same has been widely known. In addition, it is also possible to add silicon dioxide to a barium titanate-based ceramic semiconductor composition containing a rare earth element, tantalum, niobium, or antimony, and to improve the electrical characteristics of the ceramic semiconductor composition by firing in the presence of oxygen. It has been proposed (see JP-A-53-59888).

[Problems to be solved by the invention]

However, the conventional method for manufacturing a barium titanate ceramic semiconductor has a problem that it is difficult to obtain an element having a positive temperature coefficient of resistance at a temperature equal to or higher than the Curie point and having a very small resistivity at room temperature. doing.

[Means for solving the problem]

In order to solve the above problems, a method for producing a barium titanate porcelain semiconductor according to the present invention comprises: adding a semiconducting agent to a barium titanate base composition containing a Curie point transfer substance; Is characterized in that only Sb ₂ O ₃ is used as a semiconducting agent with respect to the barium titanate base composition in order to lower the room temperature resistivity. Incidentally, amount of Sb ₂ O ₃ is preferably in the range of 0.075 mol% ～0.14 mol%.

(Operation)

According to the above configuration, 0.07 added as a semiconducting agent
5 mol% to 0.14 mol% of Sb ₂ O ₃ can be easily made into a semiconductor and the resistivity at room temperature can be set smaller, so it can be used in circuits with small current capacity. A low-resistance PCT element having excellent properties can be manufactured.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The present embodiment is a method for producing a barium titanate ceramic semiconductor comprising firing a barium titanate base composition containing a Curie point transfer material by adding a semiconducting agent,
As a semiconducting agent, 0.070 mol% to 0.180 mol% of antimony oxide (Sb
_When only ₂ O ₃ ) is used, how the resistivity at room temperature changes depending on the addition amount of Sb ₂ O ₃ , and as a result, the preferable addition amount of Sb ₂ O ₃ for the production of barium titanate ceramic semiconductor Are disclosed to limit the range of

In this embodiment, strontium carbonate (SrCO ₃ )
0.070 mol% to 0.150 mol% of antimony oxide (Sb ₂ O ₃ ) is blended with the barium titanate base composition containing the Curie point transfer material such as It contains manganese (MnCO ₃ ) and silicon dioxide (SiO ₂ ) as a voltage-dependent stabilizer.

This composition 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 composition was crushed, and added with an aqueous solution of 2 wt% to 8 wt% of PVA (polyvinyl alcohol) in an automatic mortar.
Mix for 6 hours, dry and pulverize well. After the powder thus formed is molded in a disc-shaped molding machine, the molded product is held at 1300 ° C. to 1400 ° C. for 0 to 10 hours and fired to obtain a barium titanate ceramic semiconductor.

Hereinafter, the present invention will be described in more detail based on [Example 1] to [Example 4].

[Example 1] Anhydrous barium carbonate (BaCO ₃ , Nippon Kagaku Kogyo's high-purity product) 68.07 g, high-purity titanium dioxide (TiO ₂ , Toho Titanium Co., Ltd.) 29.01 g, anhydrous strontium carbonate (SrCO ₃ , Honjo Chemical Co., Ltd.) ) 2.68 g, manganese carbonate (MnCO ₃ , 99.9% manufactured by Wako Pure Chemical Industries) 0.0209 g, silicon dioxide (SiO ₂ , US-85 manufactured by Toshiba Ceramics) 0.1091 g, antimony oxide (Sb
₂ O ₃ , 99.99% reagent manufactured by Rare Metallic Co.) 0.1058 g inside diameter 2
After placing in a 00 mm alumina mortar and wet mixing in an automatic mortar for 3 hours in the presence of ethanol (special grade reagent), the mixture was dried at 130 ° C. 90 m of the dry mixture
mx 90mm alumina crucible (Mitsubishi Mining Cement, DFA-
PS99), this was placed in an electric furnace, heated at a heating rate of 180 ° C./h, and calcined at 1150 ° C. for 2 hours.

After crushing the calcined product in a mortar,
A 2 wt% aqueous solution of A (polyvinyl alcohol) was mixed with about 100 cc for 3 hours, and dried at 130 ° C.

The dried product thus obtained is pulverized well in a mortar,
PVA compound powder molding machine [12.5mm (diameter) x 35mm
(Height)] and molded under 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 Heating 800 ° C Hold for 2 hours 800 ° C to 1360 ° C Heating up to 150 ° C / h 1360 ° C Hold for 15 minutes 1360 ° C to 1000 ° C 360 ° C / h After cooling to room temperature, apply an ohmic silver electrode (manufactured by Degussa) to the disk surface of the tablet-like molded product, and apply 850 ° C. For 5 minutes to form an electrode, 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 ceramic semiconductor sample.

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

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0010Sb ₂ O ₃ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) at which a region showing a positive temperature coefficient of resistance occurs is 103
° C, and the rise width of the resistance was 4.2 digits. At this time, the resistivity at room temperature was 14.00 Ω · cm.

Example 2 68.05 g of anhydrous barium carbonate (BaCO ₃ ), 29.00 g of high-purity titanium dioxide (TiO ₂ ), and anhydrous strontium carbonate (SrC)
O ₃ ) 2.68 g, manganese carbonate (MnCO ₃ ) 0.0209 g, silicon dioxide (SiO ₂ ) 0.1090 g, antimony oxide (Sb ₂ O ₃ ) 0.1375
A barium titanate ceramic semiconductor sample was obtained in the same manner as in Example 1 except that g was used.

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

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0013Sb ₂ O ₃ As a result of measuring the temperature change of the resistance of this sample, the temperature (Curie point) at which a region showing a positive temperature coefficient of resistance occurs is 105
° C, and the rise width of the resistance was 3.5 digits. At this time, the resistivity at room temperature was 4.94 Ω · cm.

Example 3 69.00 g of anhydrous barium carbonate (BaCO ₃ ), 29.02 g of high-purity titanium dioxide (TiO ₂ ), and anhydrous strontium carbonate (SrC)
O ₃₎ 2.68 g, manganese carbonate (MnCO ₃₎ 0.0209g, silicon dioxide (SiO ₂₎ 0.1091g, antimony oxide (Sb ₂ O ₃₎ 0.0741
A barium titanate porcelain sample was obtained in the same manner as in Example 1 except that g was used.

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

(Ba _0.95 Sr _0.05 ) TiO ₃ + 0.0005MnO ₂ + 0.005SiO ₂ + 0.0007Sb ₂ O ₃ The resistivity of this sample at room temperature was 3.4 × 10 ³ Ω · cm, but it did not become a semiconductor. Measurement of various properties was not possible.

Example 4 68.04 g of anhydrous barium carbonate (BaCO ₃ ), 29.00 g of high-purity titanium dioxide (TiO ₂ ), and strontium anhydrous (SrC)
O ₃₎ 2.68 g, manganese carbonate (MnCO ₃₎ 0.0209g, silicon dioxide (SiO ₂₎ 0.1090g, antimony oxide (Sb ₂ O ₃₎ 0.1587
A barium titanate porcelain sample was obtained in the same manner as in Example 1 except that g was used.

The composition of the raw materials for 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 was made into an insulator and did not become a semiconductor, and the above-mentioned characteristics could not be measured.

From the above, the results of [Example 1] to [Example 4] are summarized in Table 1 below. As is clear from Table 1, by using antimony oxide (Sb ₂ O ₃ ) as a semiconducting agent for the barium titanate base composition, the resistivity at room temperature can be made very small. In addition, the barium titanate ceramic semiconductor
Sb ₂ O ₃ addition amount dependency ([Example 1] to [Example 3]
(Corresponding to the characteristics of each sample) is as shown in FIG. That is, as shown in FIG. 1, when the added amount of barium titanate ceramic semiconductor Sb ₂ O ₃ is smaller than 0.075 mol% or larger than 0.14 mol%, the resistivity (specific resistance) at room temperature increases. Would. Therefore, amount of Sb ₂ O ₃ is preferably found to be in the range of 0.075 mol% ～0.14 mol%.

Here, methods for measuring various physical properties of samples of the above-mentioned various barium titanate ceramic semiconductors having different compounding compositions of raw materials will be described below.

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

From the plot of electrical resistance-temperature 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 measured for electrical resistance in a 25 ° C. measurement tank using a DC resistance meter (manufactured by Multimeter 3478A YHP).

In the preparation of a barium titanate porcelain semiconductor sample,
Before applying the electrode, the size (diameter and thickness) was measured on the sample, the specific resistance (ρ) was calculated by the following equation, and this was defined as the resistivity.

ρ = R · S / t ρ: specific resistance (resistivity) [Ω · cm] R: measured value of electric resistance [Ω] S: electrode area [cm ² ] t: sample thickness [cm] (3 ) Measurement of the rise width of the resistivity Measurement of the change in the electrical resistance of the sample with respect to the temperature change (-50 ° C to 190 ° C) in the measurement of the Curie point is continued until the temperature exceeds 200 ° C. , The resistivity at the time of a sharp rise in electrical resistance at the Curie point was compared with the resistivity at 200 ° C., and the logarithm of the number of digits was defined as the rise width of the resistivity.

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

[Effects of the Invention] The method for producing a barium titanate porcelain semiconductor according to the present invention comprises, as a semiconducting agent, 0.075 mol% to 0.14
It is configured to use only mol% of Sb ₂ O ₃ .

Therefore, it can be easily made into a semiconductor, has a positive temperature coefficient of resistance at a temperature higher than the Curie point, and can set a lower resistivity at room temperature, so that it can be used in a circuit having a small current capacity. This has the effect that a low-resistance PTC element with excellent versatility that can be manufactured can be manufactured.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and 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 oxide (Sb ₂ O ₃ ).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-95673 (JP, A) JP-A-58-147004 (JP, A) JP-A-51-47292 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01C 7/02

Claims (1)

(57) [Claims] 1. A method for producing a barium titanate porcelain semiconductor comprising a step of adding a semiconducting agent to a barium titanate base composition containing a Curie point transfer substance, followed by firing, wherein the barium titanate base composition is used as a semiconducting agent. On the other hand, a method for producing a barium titanate porcelain semiconductor characterized by using only 0.075 mol% to 0.14 mol% of Sb ₂ O ₃ to lower the room temperature resistivity.