JPH0788250B2 - Positive characteristic semiconductor porcelain with reduction resistance - Google Patents

Description

TECHNICAL FIELD The present invention relates to a positive temperature coefficient semiconductor porcelain having PTC characteristics in which the electric resistance value remarkably increases when the Curie temperature is exceeded. The present invention relates to a positive-characteristic semiconductor porcelain having reduction resistance, which is mainly used for a self-temperature control type heater, a temperature sensor, etc. used in a reducing gas atmosphere.

[Prior Art] Conventionally, barium titanate was added with a rare earth element such as Y, La, Sm, Ce, or Ga or a transition element such as Nb or Ta.
It is known that porcelain fired at 00 to 1400 ° C exhibits a so-called positive characteristic (PTC characteristic) in which the electric resistance value suddenly increases at the Curie point. Utilizing this characteristic, it is used for heaters, temperature sensors and the like.

A conventional semiconductor device using a positive-characteristic semiconductor porcelain mainly composed of barium titanate semiconductor has a characteristic PTC characteristic when used in a reducing atmosphere such as hydrogen gas or gasoline. There was a problem of deterioration.
For example, when used as a self-temperature control type heater, due to deterioration of PTC characteristics (hereinafter referred to as RT deterioration),
There was a problem that the resistance value did not rise even at the temperature to be controlled, and in the worst case, the PTC element was melted and damaged due to energization. It is also known that RT deterioration does not occur only in a reducing atmosphere, but RT deterioration also occurs to some extent in a neutral atmosphere such as nitrogen or argon gas.

From the above, the use environment of the semiconductor element using the sexual characteristic semiconductor porcelain having the barium titanate semiconductor as its main component must be limited. When used in an environment of the above reducing atmosphere, as shown in FIG. 4, the element 11 must be enclosed in a case 4 made of resin or metal and shielded from the environment. There wasn't. Therefore, problems such as fixed price of performance due to deterioration of heat dissipation and high cost due to increase in the number of parts and assembling steps have occurred.

[Problems to be Solved by the Invention] The present invention overcomes the above-mentioned problems and provides a positive-characteristic semiconductor porcelain having good reduction resistance and not requiring encapsulation of an element in a predetermined case. The purpose is to

The present invention also relates to an improvement of a reduction-resistant positive-characteristic semiconductor porcelain (patent application No. 59-281418) according to an unknown prior application filed by the same applicant as the present application in order to overcome the above-mentioned conventional technique. In the positive characteristic semiconductor porcelain according to the previously unknown prior application, the flux component is 0.14 to 2.88 parts by weight of Ti.
O ₂ , 0.1-1.6 parts by weight Al ₂ O ₃ , and 0.1-1.6 parts by weight SiO
_It consists of ₂ and. In the present invention, this 3
The lithium compound is further added to the flux component consisting of the components to achieve the desired purpose.

[Means for Solving the Problems] The positive-characteristic semiconductor ceramic having reduction resistance of the present invention is a positive-characteristic semiconductor ceramic which is used by being exposed to the reducing atmosphere without being sealed in the reducing atmosphere. The barium titanate-based composition, and 0.2 to 1 per 100 parts by weight of the barium titanate-based composition.
6 parts by weight of alumina (Al ₂ O ₃ ), 0.14 to 2.88 parts by weight of titanium dioxide (TiO ₂ ), 0.1 to 1.6 parts by weight of silicon dioxide (Si
O ₂ ), and with respect to 100 mol of the barium titanate-based composition, the lithium content in terms of lithium contained is 0.
It is characterized in that it is composed of a flux component composed of a lithium compound in an amount of 04 to 2.0 mol. Here, the flux component refers to an auxiliary agent having a compositional component contained in the porcelain after sintering, and when the raw material of the auxiliary agent is referred to as a flux raw material, the two are distinguished.

Barium carbonate (BaC), which is the main component of barium titanate used in the reduction-resistant positive-characteristic semiconductor ceramics of the present invention, is used.
O ₃ ) and titanium oxide (TiO ₂ ) are usually mixed in equimolar amounts. However, it does not have to be equimolar depending on the purpose of use,
A barium titanate-based composition represented by the general formula (1) or (2) can also be used.

Ba ₁ xM ³ xTiO ₃ (1) BaTi ₁ yM ⁵ yO ₃ (2) Here, M ³ and M ⁵ are semiconducting agents selected from commonly used rare earth elements and transition elements, and M ³ As Y, La,
It may be any rare earth element such as Sm, Ce or Ga, and M ⁵ may be any transition element such as Nb or Ta. Also x and y
It is desirable that the values of 0.001 to 0.005 and 0.0005 to 0.005, respectively.

The flux component, which is the greatest feature of the present invention, is alumina (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), silicon dioxide (Si
O _2), and is composed of a lithium compound, the addition ratio of each flux component, compared barium titanate based 100 parts by weight of the composition, Al ₂ O ₃ is 0.2 to 1.6 parts by weight, TiO ₂ is from 0.14 to 2.8
8 parts by weight, SiO ₂ is 0.1 to 1.6 parts by weight and the lithium compound is 100 mol of the barium titanate-based composition, and the lithium content is 0.04 to 2.0 in terms of lithium contained.
It is a mole. It is necessary that each of the flux components be added within the above range, and it is not preferable if the added amount is less than the above range or too much. Furthermore, as the amount of the flux component added increases, the specific resistance of the PTC semiconductor ceramic tends to increase. In order to solve this problem, the flux component is 0.2 to 0.4 parts by weight of Al ₂ O ₃ , TiO _{2 with} respect to 100 parts by weight of the barium titanate-based composition.
Is 0.14 to 1.15 parts by weight, and SiO ₂ is 0.2 to 0.8 parts by weight, and 100 parts of a barium titanate-based composition as a lithium compound.
In the case of molar amount, it is desirable that the lithium content is 0.1 to 0.8 mol in terms of lithium contained. If each component is within this content range, the specific resistance of the positive-characteristic semiconductor porcelain obtained will be 80Ω · cm or less, which is suitable for application to automobile parts.

The lithium compound, which is one of the above-mentioned flux components, is usually lithium oxide (Li ₂ O), but is not limited thereto, and as a lithium compound under a predetermined sintering condition, the positive temperature coefficient semiconductor porcelain of the present invention is used. As long as it is included in. The raw material of the lithium compound may be Li ₂ O, lithium carbonate (Li ₂ CO ₃ ), lithium nitrate (Li
NO ₃ ), lithium chloride (LiCl), lithium hydroxide (LiO
H) or the like, or a mixture thereof. Raw material is much in calcination or firing in manufacturing processes often seems to be a Li ₂ O, kinds of raw materials, may be one which does not become Li ₂ O by firing conditions and the like, a part of Li ₂ O
It does not have to be

Li ₂ CO ₃ or Li ₂ O is usually used as the raw material.

Even in the above-mentioned flux components Al ₂ O ₃ , TiO ₂ or SiO ₂ ,
The components contained in the positive temperature coefficient semiconductor porcelain after firing are Al
₂ O ₃ , TiO ₂ or SiO ₂ may be used, and the raw material thereof is not limited to the oxide. Therefore, the raw material may be a hydroxide of each metal such as Al.

The above flux component is Ba, which is the main agent of barium titanate.
It is mixed with CO ₃ and TiO _2, etc. and fired. By adding the above-mentioned four components within the above range, it is possible to obtain a baking characteristic semiconductor device having extremely good reduction resistance. Further, by changing the ratio of each of the above components within the above range, or by changing the addition amount of the flux component as a whole, it becomes possible to adjust the growth degree of the crystal particles of the positive characteristic semiconductor device, and the positive characteristic having various performances. It is possible to obtain a semiconductor device.

In addition to the above components, the positive temperature coefficient semiconductor porcelain of the present invention includes titanates such as strontium titanate or lead hatitanate,
A zirconate such as barium zirconate or a stannate such as barium stannate may be contained. The lead component was added before calcination with lead oxide (PbO) and dissolved during calcination, rather than added after calcination with PbTiO ₃ and solid solution with BaTiO ₃ during calcination. Is more effective in reducing resistance.

It is also preferable to add elements such as Pb, Sr, Zr and Sn as Curie point control agents, and it is also preferable to add a trace amount of elements such as Mn, Fe and Co as additives for improving PTC characteristics.

The positive temperature coefficient semiconductor porcelain of the present invention is mixed in the same manner as in the conventional method,
It is obtained by molding and firing. The process of making the semiconductor is as follows.

First, barium titanate is produced at a temperature of 800 to 1100 ° C, but the crystal lattice is still disordered in this state. 1200 ~
At 1280 ° C, part of the flux component begins to melt, and barium titanate rapidly grows into a semiconductor. Then, the flux component is completely melted, and the barium titanate particles are converted into a semiconductor in the liquid phase of the flux component. In the cooling process after firing in this way, the liquid phase of the flux component is solidified while covering the barium titanate semiconductor particles, and is integrated.

Although the mechanism by which the positive-characteristic semiconductor porcelain of the present invention has resistance to reduction is not clear, it is presumed that the flux component covers the barium titanate semiconductor grain boundary and protects it from the reducing atmosphere. Further, the water absorption rate of the conventional positive temperature characteristic semiconductor device was about 0.5% by weight, whereas the water absorption rate of the positive temperature characteristic semiconductor porcelain of the present invention was about 0.01% by weight, which was almost zero.
%, The water absorption rate is significantly reduced. For this reason, it is considered that the reduction substance invasion is reduced, which is one of the reasons for the reduction resistance.

EFFECTS OF THE INVENTION The positive temperature coefficient semiconductor porcelain of the present invention hardly causes RT deterioration even when it is used in a reducing atmosphere, and does not cause reduction deterioration even when the Curie temperature becomes high, and has excellent PTC characteristics. Have Therefore, not only in a neutral atmosphere such as nitrogen or carbon dioxide, but also in a reducing atmosphere such as hydrogen gas or gasoline, it is not necessary to seal with resin or metal, and it can be used in an exposed structure. The performance is improved, the degree of freedom in product design is expanded, and it is particularly effective for cost reduction.

Further, since the raw characteristic semiconductor porcelain of the present invention is not easily affected by impurities, firing conditions, and the amount of addition of the semiconducting agent,
It is much easier to manufacture than in the past, because cheap industrial raw materials can be used.

From the above, the raw characteristic semiconductor porcelain having reduction resistance of the present invention, especially those having a small specific resistance, for example, 100 Ω · cm or less, for example, as an automobile part, an intake heating heater, a fuel heater or a temperature sensor, etc. It can be applied to various products.

[Test Example] The performance of the positive temperature coefficient semiconductor porcelain of the present invention will be described below with reference to test examples.

(Test Example 1) - I in the discussion this test example of the body reducing the hydrogen gas _{BaCO 3, TiO 2, Al 2} O 3, SiO 2, yttrium oxide _{(Y 2 O 3), Li} 2 CO 3 or Li ₂ O and PbO or PbT
Made from iO ₃ . All of these were industrial raw materials. Each of these raw materials was blended into 55 types of compositions shown in Tables 1 to 3, and each was pulverized and mixed with agate stone by a ball mill for 20 hours in a wet manner. In addition, in Tables 1 to 3, the value showing the addition ratio of Li ₂ CO ₃ or Li ₂ O as the flux raw material represents the mol% of this raw material with respect to Ba and Pb, as indicated by * 2. Then, these mixtures were dried and then calcined at a temperature of about 1100 ° C. for 4 hours. A small amount of manganese dioxide (MnO ₂ ) was added to the thus obtained calcined product in order to improve the withstand voltage (R, T, characteristics), and It was pulverized and mixed by wet milling with Menoi cobbles for 20 hours in a ball mill. 10% as binder in each mixed powder after drying
1% by weight of polyvinyl alcohol aqueous solution is added and mixed,
Press molding was performed at a pressure of 80 kg / cm ² . These molded products were fired in air at about 1320 ° C for about 1 hour to give a diameter of 25 mm and a thickness of 2.
A disc-shaped positive-characteristic semiconductor porcelain of 5 mm was manufactured.

The specific resistance of the positive-characteristic semiconductor porcelain related to Test Example No. 24 is 2
6Ω ・ cm, Curie point is 200 ℃, withstand voltage is 150V,
In addition, the water absorption rate is 0.01 wt%, which is almost zero and the conventional element (0.
5 wt%) was extremely low.

In order to investigate the characteristics of the 55 types of positive-characteristic semiconductor porcelain thus obtained, Ni-Ag electrodes (Ni electroless plating, Ag paste) were applied to both sides of each positive-characteristic semiconductor porcelain, and the electrical resistance value at 25 ° C in the atmosphere ( The specific resistance R ₀ ) was measured, and the results are shown in Table 1 and Table 2.
The results are shown in Tables and Table 3. Also, put each PTC semiconductor porcelain in a hydrogen gas atmosphere, and measure the electrical resistance (R ₁ ) immediately after putting each PTC semiconductor porcelain and the electrical resistance (R ₂ ) after 30 minutes at 300 ° C. Then, the resistance change rate (ΔR) was measured by the following equation (3).

ΔR = 100 × (R ₂ −R ₁ ) / R ₁ (3) Here, the closer R ₂ is to R ₁ , that is, the closer ΔR is to 0, the better the reduction resistance.

Evaluation of each positive-characteristic semiconductor porcelain is as follows: Table 1, Table 2, and Table 3 show that ΔR is 0 to -10% (○), -10 to -50% is (△), and less than -50% is (x). Shown in the table.

In Table 1, 0.2 to 1.6 parts by weight of AlO ₃ (hereinafter referred to as “weight%”) as a flux component is 0.14 to 2.88 weight% of TiO _{2 and} 0.1 of SiO _{2 as a} flux component with respect to 100 parts by weight of the barium titanate-based composition.
~ 1.6 wt% and the lithium compound is 0.04 to 2.0 mol (hereinafter referred to as mol%) in terms of lithium atom based on 100 mol of the barium titanate-based composition.
As shown in Table 1, when the addition amount of a raw material compound such as Li ₂ CO ₃ is shown, it is referred to as raw material mol%. ) The positive characteristic semiconductor porcelain (N18 to 27, 29, 30, 34 to 55) included is a four-component positive characteristic semiconductor porcelain (No. 17, 28, 31) other than this flux.
.About.33), .DELTA.R is as small as -0.2 to -9.4 (-12 to -41 in Comparative Example), and is clearly excellent in reduction resistance. And
Looking at No. 31 to 33, No. 34 to 37, and No. 38 to 41, the specific resistance is S
It can be seen that it has a minimum when iO ₂ is between 0.1 and 0.16% by weight. When the SiO ₂ content is 0.1% by weight or 1.6% by weight, the specific resistance may exceed 80 Ω · cm, so it can be seen that this range is the lower limit and the upper limit of the amount of SiO ₂ . Also,
Particularly desirable range of Al ₂ O ₃ is 0.2 to 0.4% by weight, TiO ₂
Is 0.41 to 1.15% by weight, SiO ₂ is 0.2 to 0.8% by weight, and the lithium content in the lithium compound is 004 to 0.8% by mole. Positive characteristic semiconductor porcelain (NO. 18 to 22, 24 to 27, 29, 35, 36, 3
9, 40, 49 to 51) have a small specific resistance (R ₀ ) of 80 Ω · cm or less, a small ΔR, and further excellent resistance to reduction, and are therefore most suitable for application to automobile parts.

(Test Example 2) -Study on reduction resistance in sour gasoline Next, using a raw material having the same composition as that used in Test Example 1, mixing, molding and firing were performed in the same manner as in Test Example 1 to obtain a diameter.
A disc-shaped positive-characteristic semiconductor porcelain having a thickness of 25 mm and a thickness of 2.5 mm was manufactured. The obtained positive-characteristic semiconductor porcelain was provided with a Ni-Ag electrode on the surface in the same manner as in Test Example 1, and the electric resistance of each positive-characteristic semiconductor porcelain was measured substantially continuously in the air from room temperature to 300 ° C. Then, the PT of the solid line (a) shown in the conceptual diagram of FIG.
A curve representing the C characteristic was obtained. Next, each positive-characteristic semiconductor porcelain was immersed in sour gasoline, and an immersion current durability test was performed in which a voltage of 30 V was applied for 200 hours or more. Here, sour gasoline is gasoline that has been oxidized to generate peroxides and acids, and is used for accelerated tests. After the immersion current durability test, the positive resistance semiconductor porcelain was measured for the electrical resistance in the atmosphere from room temperature to 300 ° C almost continuously, and the curve showing the PTC characteristic of the broken line (b) in Fig. 2 was obtained. . The RT deterioration (A) shown in FIG. 2 was obtained from the difference between the two obtained curves, and the results are shown in Tables 1 to 3. The RT deterioration (A) is obtained by the following equation.

log (R'max / R'min) -log (Rmax / Rmin) = RT deterioration (A) (R ... resistance value before endurance test, R '... resistance value after endurance test, max ... maximum value, min… Minimum value) In Tables 1 to 3, there is a part where the measurement result is not described, but this is because the positive resistance semiconductor porcelain with a specific resistance of 100 Ω · cm or more shows sufficient heat generation in the immersion current durability test. It was not measured because it was not possible to obtain reliable data. In addition, in the determination of the result, the degree of (A) is within 1 (o), 1-2 is (Δ), and 2 or more is (x).

In Tables 1 to 3, the positive temperature coefficient semiconductor porcelain of the present invention (No. 18
~ 22, 24-27, 29, 34-37, 39-41, 43, 44, 49-51)
Has a logarithmic value of +0.1 to -0.9 compared to other positive-characteristic semiconductor porcelains (for example, No. 17), and (No. 17 has -1.8) is clearly excellent in reducibility. In the test examples of the present invention, Al ₂ O ₃ which is a desirable range is 0.2
0.4 wt% TiO ₂ is 0.4 to 1.15 wt% lithium content of SiO ₂ is in the 0.2 to 0.8 wt% and the lithium compound is 0.1 to 0.8
In the case of mol% range (No. 19-22, 24-27, 2935, 36, 3
9, 40, 49 to 51), the RT deterioration is as small as +0.2 to -0.7 and the specific resistance is as small as 80 Ω · cm or less.

(Study of Results of Test Examples 1 and 2) (1) Investigation of Raw Material Lithium Compound The raw material lithium compound showed almost the same performance in both Li ₂ CO ₃ and Li ₂ O (No. 24 and 25, No, 26). And 27).

(2) Examination of composition ratio of each flux component When the lithium raw material compound (Li ₂ O) is 0.02, 0.05, 0.1, 0.3, 0.4, 1.0 raw material mol% (No. 18 to 23, respectively, the lithium content is The value is twice as high as each of these values). In particular, the lithium content is 0.1, 0.2, 0.
6, 0.8 mol% (Nos. 19 to 22) is more preferable because the RT deterioration is further small and the specific resistance is about 80 Ω · cm or less. However, when it is 0.02 and mol% (No. 17), the performance judgment for both hydrogen and sour gasoline is Δ, and the reduction resistance for both is insufficient.

When the composition ratio of Al ₂ O ₃ is 0.1% by weight (No. 28, 31 to 3
3), Reduction resistance to hydrogen or sour gasoline is △ or ×, and reduction resistance is not good.

In the test examples of Tables 1 to 3, the flux component was Al.
_In the case of 4 components of ₂ O ₃ , TiO ₂ , SiO ₂ and lithium compound, the proportion of each flux component in the positive temperature coefficient semiconductor porcelain of the present invention is 0.2 to 1.6% by weight of Al ₂ O _{3 and} 0.14 to 2.88 of TiO.
% By weight, 0.1 to 1.6% by weight of SiO _{2 and} 0.04 to 2.0 mol% of lithium in the lithium compound (all test examples except No. 17, 28, 31 to 33 of No. 17 to 55), Excellent reduction resistance to hydrogen or sour gasoline.

The Curie temperature of the three-component flux of Al ₂ O ₃ , TiO ₂ and SiO ₂ (eg No. 11 and 12) is 150 ℃ or higher (each
In contrast to the present invention (for example, No. 24), there is no problem even when the Curie temperature is 200 ° C., and by adding a lithium compound, PTC with a high Curie temperature is obtained. The reduction resistance is also good for semiconductor porcelain.

(3) Lead addition method For positive-characteristic semiconductor porcelain with a high Curie point, it is better to add P rather than PbTiO ₃ after calcination (No. 10-12, 24, 25).
BO added before calcination and solid solution with BaTiO ₃ during calcination (No. 13 to 15, 26, 27) is effective for reduction resistance because Pb is less scattered and the water absorption rate is lower. is there.

(Test Example 3) Of the positive temperature coefficient semiconductor porcelain used in Test Example 1, No. 12 was selected as the composition of the comparative example and No. 27 was selected as the composition of the present invention, and mixing, molding and firing were performed in the same manner as in Test Example 1. Going, diameter 25m
A disc-shaped positive-characteristic semiconductor porcelain having a thickness of 2.5 mm and a thickness of 2.5 mm was manufactured. Ni-Ag electrodes were applied on both sides of the obtained two types of positive-characteristic semiconductor porcelain, and 300% was set in hydrogen gas in a reducing atmosphere.
It was left at ℃ for 30 minutes. The electric resistance value of each positive-characteristic semiconductor porcelain during the 30 minutes was measured almost continuously, and the resistance change rate was calculated based on the electric resistance value immediately after being put into the reducing atmosphere. The results are shown in Fig. 1. Show. As is clear from FIG. 1, the positive characteristic semiconductor ceramics having a three-component flux composition (higher performance than the conventionally known positive characteristic semiconductor ceramics) No. 12 has a resistance change rate of 68% in hydrogen gas ( Although the ΔR) is decreased, in the positive temperature coefficient semiconductor porcelain No. 27 of the present invention, the resistance change rate (ΔR) in hydrogen gas is decreased only by 9.1%, and there is almost no change. That is, the positive temperature coefficient semiconductor porcelain of the present invention has very little change in electric resistance even in a reducing atmosphere of hydrogen gas, and is extremely excellent in reduction resistance.

Although the mechanism of improvement in reduction resistance is not clear, the addition of Al ₂ O ₃ , TiO ₂ , SiO ₂ and the flux component of the lithium compound significantly reduced the water supply rate and reduced the penetration of reducing substances. Is also considered to be a factor.

(Test Example 4) Torque performance of each engine when the positive temperature coefficient semiconductor porcelain (No. 24) according to the present invention has an exposed structure as shown in FIG. 3 or a sealed structure as shown in FIG. FIG. 5 shows the results of evaluating the above and comparing both. The engine conditions in this case were 1600 rpm (1500 cc), 4.5 kgm, W / choke, and A / F: 11-12.

According to this result, when the positive temperature coefficient semiconductor porcelain according to the present invention is used in the exposed structure, the engine torque performance becomes better than that in the case of the conventional sealed structure.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in electric resistance value in hydrogen gas, and FIG. 2 is a diagram showing RT deterioration in sour gasoline. FIG. 3 is an explanatory diagram in which the positive-characteristic semiconductor porcelain having reduction resistance of the present invention is applied to an intake air heater with an exposed structure. FIG. 4 is an explanatory diagram in which a conventional positive temperature coefficient semiconductor porcelain is applied to an intake air heater with a sealed structure. FIG. 5 is a diagram showing the engine torque performance when the intake air heaters shown in FIGS. 3 and 4 are used. 1, 11 …… Positive characteristic semiconductor porcelain 2, 21 …… Heat insulator of Casolin engine 3, 31 …… Spring, 4 …… Case (A) …… RT deterioration (a) …… Initial state (b)… … After durability test

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Jun-Ichi, 1-1, Showa-machi, Kariya, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Naoto Miwa, 1-1, Showa-machi, Kariya, Aichi Prefecture, Nippon Denso Incorporated (56) References Japanese Patent Publication Sho 48-6352 (JP, B1)

Claims (4)

[Claims] 1. A positive-characteristic semiconductor porcelain used by being exposed to a reducing atmosphere without being sealed in a reducing atmosphere, comprising: a barium titanate-based composition; and 100 parts by weight of the barium titanate-based composition. 0.2 to 1.
6 parts by weight of alumina (Al ₂ O ₃ ), 0.14 to 2.88 parts by weight of titanium dioxide (TiO ₂ ), 0.1 to 1.6 parts by weight of silicon dioxide (Si
O ₂ ), and a flux component composed of a lithium compound having a lithium content of 0.04 to 2.0 mol in terms of lithium atoms contained with respect to 100 mol of the barium titanate-based composition. A positive-characteristic semiconductor porcelain having reduction resistance. 2. The flux component is 0.2 to 0.4 parts by weight of alumina (Al ₂ per 100 parts by weight of the barium titanate-based composition).
O _3), 0.14~1.15 parts by weight of titanium dioxide (TiO _2), 0.2
To 0.8 parts by weight of silicon dioxide (SiO ₂ ), and a lithium compound having a lithium content of 0.1 to 0.8 mol in terms of lithium atoms contained with respect to 100 mol of the barium titanate-based composition. A positive-characteristic semiconductor porcelain having reduction resistance according to claim 1. 3. The lithium compound is lithium oxide (Li ₂ O).
The positive-characteristic semiconductor porcelain having reduction resistance according to claim 1. 4. A barium titanate-based composition has the general formula Ba _1-x M
³ _x TiO ₃ or BaTi _1-y M ⁵ _y O ³ (M ₃ is Y, La, Sm,
Rare earth elements such as Ce and Ga, M ⁵ is a transition element such as Nb and Ta, x is
The positive-characteristic semiconductor porcelain having reduction resistance according to claim 1, which has a composition of 0.001 to 0.005 and y is 0.0005 to 0.005, respectively.