JPS6031794B2 - Barium titanate semiconductor porcelain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides titanic acid/IJ having positive resistance-temperature characteristics.
The present invention relates to aluminum-based semiconductor porcelain.

Conventionally, barium titanate has been known as an insulator with a high resistivity of 1.00.degree. At least one kind of oxide, such as bismuth (Bi) or tantalum (Ta), is added and fired, or only the grain boundaries of the barium titanate aggregates, which are converted into a semiconductor by firing in a cyclic atmosphere, are removed. By oxidizing, semiconductor porcelain with a low resistivity of 10 to 1 p.p.m. at room temperature is obtained. and,
The barium titanate-based semiconductor porcelain obtained in this way has a resistance-temperature characteristic of barium titanate that has low resistance at low temperatures and high resistance at high temperatures, with a point corresponding to the point temperature of barium titanate. It has the characteristic that the electric resistivity rises suddenly and reversibly.Using this positive resistance temperature (called PTC characteristic), it can be used as a material for temperature control, current control, etc. It has been used for a wide range of purposes.

However, such semiconductor porcelain has the disadvantage that even a slight change in the amount of the semiconducting agent added causes a sudden change in resistivity, making it unsuitable for practical use and lacking in reproducibility. In addition, in its manufacture, there were drawbacks such as high semiconductor conversion temperature, large particle growth, coarse particles, and the tendency to incorporate pores into the particles. Furthermore, the semiconductor porcelain is PTC.
When used in switching elements or current-controlled heating elements that require a large change in resistivity in the temperature range and a rapid rise, M may be used as an additive.
n etc. are generally used.

However, when adding these, there is a problem in that very small changes in the characteristics can greatly change the resistivity at room temperature, so minute adjustments of a few thousandths of a percent are necessary. be. The present invention is based on the fortuitous discovery that the addition of titanium nitride (TIN), zirconium nitride (ZrN) or silicon carbide (SIC) is effective in eliminating the above-mentioned drawbacks.

That is, the barium titanate-based semiconductor porcelain of the present invention contains barium titanate and trivalent metal elements such as yttrium, lanthanum, cerium, samarium, disprosium, and antimony, and pentavalent metal elements such as niobium, tantalum, and bismuth. Titanium nitride (TIN)
, zirconium nitride (ZTEN) or silicon carbide (SIC
) at least one of the following: 0.1 None, 2. It is characterized by containing % by weight of . The barium titanate-based semiconductor ceramic of the present invention is easy to manufacture because the resistivity does not change rapidly even if the proportion of components such as yttrium as a semiconductor agent changes.

Furthermore, the barium titanate semiconductor ceramic of the present invention undergoes solidification and becomes a semiconductor at a lower temperature than conventional ceramics, so its crystal grains are small and dense. Furthermore, the resistance change in the PTC region is rapid and large during the change within a wide range of addition amounts of the semiconductor agent. To manufacture the barium titanate-based semiconductor ceramic of the present invention, titanium nitride, zirconium nitride, and silicon carbide powder are mixed with conventional barium titanate-based semiconductor raw material powder, and the mixture is fired in the atmosphere.

Typical raw materials for barium titanate include barium carbonate (BaC03) and titanium oxide (Ti02). The raw materials for barium titanate are not limited to those listed above, but
If there are too many impurities, the desired semiconductor cannot be obtained.

In particular, impurities such as iron (Fe), copper (Cu), potassium (K), sodium (Na), magnesium (Mg), and aluminum (AI) are said to have a negative effect on the semiconductor formation of barium titanate. . As the semiconductor agent, one or more of a trivalent metal element such as yttrium or a pentavalent metal element such as tantalum is used as described above. Among them, oxides of rare elements are representative.
The typical manufacturing process is raw material blending → wet mixing → dehydration drying →
The process is calcination → crushing → granulation → molding → main firing.

It is also preferable to use a stainless steel pot lined with urethane rubber and agate jewelry to prevent impurities from entering during the wet mixing and grinding steps. False dawn is carried out at around 900 degrees Celsius or 1100 o'clock in the morning.

The purpose of this is to synthesize barium titanate (Board Ti03),
This is to make the fired product more delicate during the main firing. Incidentally, titanium nitride, zirconium nitride, or silicon carbide according to the present invention may be blended at the time of blending the raw materials, or may be blended during the pulverization step of pre-firing. The barium titanate semiconductor ceramic of the present invention will be explained below along with experimental results. Experimental example
1 This experimental example uses conventional barium yttrium titanate (
It shows the relationship between the firing temperature and room temperature resistivity of Ba, YxTi03) semiconductors, and the relationship between the firing temperature and room temperature resistivity when titanium nitride, zirconium nitride, and silicon carbide are added according to Examples.

The secondary barium titanate-yttrium matrix (YxTi03) has a semiconducting ceramic composition, as well as titanium nitride (T) and zirconium nitride (ZrN).
), silicon carbide (SIC) was added, and the semiconductor temperature was measured for four types.

Note that the above x was set to 0.003. B. 9 Yo. o
The composition of o3Ti03 is barium carbonate, yttrium oxide, and titanium oxide, and titanium nitride, zirconium nitride, and silicon carbide are each finely pulverized powder.
r) were used, and the compositions shown in Table 1 were blended.

Each mixture was lined with urethane rubber and mixed in a ball mill using agate cobbles as balls. After mixing, 1
I acted as a temporary lady for 2 hours at 100pm. After calcining, it was thoroughly ground using the ball mill described above. After crushing, it is placed in a mold with an inner diameter of 2 mm and molded at a press pressure of 600k9/lump, with a height of 3 skins,
A green compact with a diameter of 2Q side was obtained. Next, these green compacts are
It was fired for 1 hour at each temperature shown in Table 1 of 240:00 and 138,000.

The specific resistance of the obtained fired body was measured at room temperature (20 qo). The firing temperature and specific resistance are also shown in Table 1. As is clear from Table 1, when titanium nitride, zirconium nitride, and silicon carbide are blended, compared to the case where they are not blended, the
Semiconductorization and Akatsuki mackerel were possible at temperatures as low as 80 pm. The reason for this is currently unknown, but it is thought that the additives such as titanium nitride, zirconium nitride, and silicon carbide affect the composition of the liquid phase generated during firing. Table 1 Experimental Example 2 This experimental example is based on the conventional barium-yttrium titanate (
B1a, -xYxTi03) semiconductor yttrium (Y
) and the relationship between the amount of yttrium (Y) and the specific resistance at room temperature, and the relationship between the amount of yttrium (Y) and the specific resistance at room temperature when titanium nitride (TIN), zirconium nitride (ZrN), and silicon carbide (SIC) according to the present invention are added. It is.

As for the composition of YxTi03, barium carbonate, yttrium oxide, and titanium oxide were used as raw materials, and the amount of yttrium (Y) was blended in a range of 0.1 to 0.6 at%.

Titanium nitride, zirconium nitride and silicon carbide are each 1. Each skin t% was added. Using each of these,
Each semiconductor ceramic was obtained in the same manner as shown in Experimental Example 1. Incidentally, the firing at that time was performed at 1380q0. Yttrium (Y) of the fired body thus obtained
Figure 1 shows the relationship between the amount and room temperature specific resistance. Curve 1 is when the additive is titanium nitride, Curve 2 is when it is zirconium nitride, Curve 3 is when it is silicon carbide, and Curve 4 is when there is no additive.
It is shown by each curve. As is clear from FIG. 1, when titanium nitride, zirconium nitride, and silicon carbide according to the present invention are added, low resistivity is obtained over a range of yttrium (Y) amounts, whereas when no additives are used, In this case, a low resistivity can be obtained only in an extremely narrow range in which the amount of yttrium (Y) is around 0.3 atomic %.

Therefore, it can be seen that the titanium nitride, zirconium nitride, and silicon carbide according to the present invention greatly expand the effective addition amount range of the semiconductor agent.

Experimental Example 3 In this experimental example, the conventional barium-yttrium titanate (
This figure shows the relationship between the amount of addition and the specific resistance at room temperature when titanium nitride (TIN), zirconium nitride (ZrN), and silicon carbide (SIC) according to the present invention are added to a BaMYxTj03) semiconductor.

Each semiconductor ceramic was obtained in the same manner as in Experimental Example 1 using a barium titanate semiconductor doped with 0.3 at % yttrium (Y).

At that time, firing was performed at 1300° for 1 hour. Table 2 shows the relationship between the amount of the additive according to the present invention and the room temperature resistivity of the obtained fired body. As shown in the comparative example in Table 1, the firing temperature of barium titanate to which 0.3 at.% of yttrium (Y) was added without adding the additive according to the present invention was 13.
The specific resistance of the fired product at room temperature (20o0) at 00oo is an extremely high value (IQQ/inhibition).

Then, only when the firing temperature reaches about 1360 oo, the specific resistance becomes about 200. However, as shown in Table 2, when at least one of titanium nitride, zirconium nitride, and silicon carbide is added, the amount of addition is 0.1
The specific resistance is already low at wt%, and even if the amount added is further increased, the resistance value hardly changes up to about 2wt%. As described above, within a wide range of addition amounts of the additive according to the present invention, it was possible to convert barium titanate doped with yttrium (Y) into a semiconductor at a considerably lower temperature than when no additive is added. However, the amount added is 3. If it becomes less than %, the value of specific resistance increases. Therefore, the amount of additives added according to the present invention is 0.1% and 2%. The skin t% range is good.

In addition, in the case where two types of additives according to the present invention are mixed at 0.5 M% each, semiconductor porcelain is obtained by the same method as above, and the amount of additives according to the present invention in the obtained fired body is The relationship between this and room temperature resistivity was investigated.

The relationship is shown in Table 2. As is clear from Table 2, it can be seen that similar effects are obtained even when two types of additives according to the present invention are mixed and blended. Table 2 Experimental Example 4 This experimental example uses conventional barium yttrium titanate (
This figure shows the relationship between the amount of addition and the change in specific resistance when titanium nitride (TIN), zirconium nitride (ZrN), and silicon carbide (SIC) according to the present invention are added to a BaMYxTi03) semiconductor.

Here, the term "currently changing resistivity" means the maximum value (pmax) and minimum value (pmax) of resistivity in the relationship between temperature and resistance of semiconductor ceramics.
pmin).

Using a barium titanate semiconductor doped with 0.3 atom% yttrium (Y), the additives according to the present invention were added in various proportions, and each semiconductor ceramic was obtained in the same manner as in Experimental Example 1. Ta.

At that time, the firing temperature was 1380 qo. The relationship between the amount of the additive according to the present invention and the change in resistivity of the obtained fired body is shown in FIG. In the case of , each curve is shown as curve 7, and in the case of no additive, it is shown as point 8. As is clear from FIG. 2, when the additive according to the present invention is added, 0.1 to 2. It can be seen that the change in resistivity is 1 to 1 degree over a wide range of the addition amount of skin t%, and the value is significantly improved by about 1 degree (4 in the figure) when no additive is added.

Experimental Example 5 In this experimental example, the conventional barium titanate-yttrium (
Figure 2 shows the relationship between the amount of addition and the rate of change in resistance in the PTC region when titanium nitride (TIN), zirconium chamber (ZrN), and silicon carbide (SIC) according to the present invention are added to a Ba, TYxTi03) semiconductor. It is something to do.

Here, the resistance change rate (Δp/ΔT) is defined as follows.

△p/△T=(pmax-pmin)/(Tpmax-
Tpm[n) Tpmax: Temperature at which the specific resistance is maximum Tpmin: Temperature at which the specific resistance is the minimum The fired body obtained in Test Example 4 is used as the semiconductor ceramic sample.

The relationship between the amount of the additive and the rate of change in resistance in the PTC region according to the present invention is shown in Figure 3, where curve 9 is used as the additive when titanium nitride is used, curve 10 is used when the additive is used as zirconium nitride, and curve 10 is used when the additive is used as the additive in the PTC region. is each curve of curve 11, and the case of no additive is shown as point I2. As is clear from FIG. 3, the addition of the additive according to the present invention reduces the amount of addition from 0.1 to 2. It can be seen that the value of Δp/ΔT is greatly improved over a wide range of skin t%.

This is nothing but the fact that the rise of the resistance change is slowing down rapidly. Experimental Example 6 This experimental example uses a conventional barium-lanthanum titanate (BaMLaxTi03) semiconductor, barium-cerium titanate (EU.-xCexTi)
03) Semiconductor, barium titanate-antimony (Ba,
-xS wide Ti03) It shows the relationship between the additive and room temperature resistivity when the additive according to the present invention is added to a semiconductor.

Barium titanate, lanthanum (La), cerium (C)
e), antimony (Sb) was doped at 0.6 atomic %.

In this case, the specific resistances are 1' (i) and 1 pi (Ce), respectively.
), and IQ (Sb) was ○. 0.5 wt% of each of titanium nitride (TIN), zirconium nitride (ZrN), and silicon carbide (SIC) was added to barium titanate having each of these chemical compositions, and each semiconductor ceramic was prepared in the same manner as in Experimental Example 1. I got it. At that time, firing was performed at 1300° C. for 1 hour. Table 3 shows the relationship between the additives according to the present invention and the room temperature specific resistance of the obtained fired bodies. As is clear from Table 3, when 0.5 wt% of the additive according to the present invention is added, the range of the amount of the semiconducting agent added increases, similar to when doping yttrium (Y) as the semiconducting agent. I know it's working.

The PTC effect of these barium titanate semiconductors had a pmax/pmin of 1 to 1 p, and all exhibited excellent PTC characteristics. Table 3

[Brief explanation of drawings]

The figures show experimental examples of the present invention, Figure 1 is a diagram showing the relationship between the amount of yttrium and room temperature specific resistance in the second experimental example, and Figure 2 is a diagram showing the amount and ratio of additives according to the present invention. FIG. 3 is a diagram showing the relationship between the amount of additive and the rate of change in resistance in the PTC region according to the present invention. Figure 2 Figure 3

Claims (1)

[Claims] 1. At least one of titanium nitride, zirconium nitride, or silicon carbide is added to a barium titanate-based semiconductor consisting of barium titanate and a trace amount of a semiconductor agent in an amount of 0.1
A barium titanate-based semiconductor porcelain characterized by containing at least 2.0% by weight of barium titanate. 2. The semiconductor forming agent is a trivalent metal element such as yttrium, lanthanum, cerium, samarium, disprosium, and antimony, and a pentavalent metal element such as niobium, tantalum, and bismuth. Barium titanate-based semiconductor porcelain of scope 1.