JPH0248465A - Barium titanate-based semiconductor porcelain - Google Patents

Abstract

PURPOSE:To reduce fluctuation in resistance due to temperature change in use environment and enable excellent communication in normal use when used for communication protectors by substituting part of barium in a barium titanate-based semiconductor porcelain with a specific element and forming a solid solution. CONSTITUTION:At least one selected from the group of rare earth elements, Y, Nb, Sb and Bi as a minor additive are added to BaTiO3 or a barium titanate-based porcelain composition consisting essentially of the BaTiO3 and containing Sr, Sn or Zr added for controlling the Curie point and further plural auxiliary additives for improving positive temperature coefficient(PTC) characteristics. In the resultant barium titanate-based semiconductor porcelain, the following constitutions (a) to (o) are adopted. Part of Ba is substituted with (a) 0.001-0.1 atomic% Mg to form a solid solution, (b) 0.01-5.0 atomic% Pb to form a solid solution or (c) simultaneously 0.001-0.1 atomic% Mg and 0.01-5.0 atomic% Pb to form a solid solution.

Description

[Detailed Description of the Invention] [Field of Application of A Tojo] The present invention relates to barium titanate-based semiconductor porcelain, and in particular barium titanate used for protection against lightning surges induced in communication lines and from contact with commercial power sources. This relates to semiconducting ceramics.

[Prior art] Conventional barium titanate-based semiconductor porcelain is BaTi03
(barium titanate) or BaTiO3 (barium titanate), which is mainly supplemented with strontium (Sr), tin (S n), or zirconium (Zr) to control the Curie point. , yttrium (Y), niobium (Nb)
), antimony (Sb), and bismuth (B+)R as a trace additive for semiconductor formation. Semiconductor porcelain having a positive temperature coefficient of resistance can be obtained by adding such additives.

However, since the temperature change rate of resistance is small with only such flit additives, manganese (Mn), silicon (Si)
), aluminum (Al), titanium (T i )”!
By adding p oxide to make the gradient of its resistance-temperature characteristics steeper, it can be used in non-contact switches, overheat prevention parts for electronic devices, and the like.

[Problem to be solved by the invention]

However, in conventional barium titanate-based semiconductor porcelain, when it is used as a protector for communication lines and installed outdoors, the resistance value increases and decreases due to large temperature changes between day and night. However, depending on the degree of change, it may interfere with normal communication.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce resistance fluctuations due to temperature changes in the usage environment.
To provide a barium titanate-based semiconductor porcelain which can perform communication satisfactorily during normal use. The characteristic of lithium-based semiconductor porcelain is that a part of barium (Ba) is mixed with 0.0Of ~ O, fat percent of magnesium (
Mg) as a solid solution.

The barium titanate semiconductor ceramic of the second invention is characterized in that a portion of barium (Ba) is replaced with 0.01 to 5.0 at percent lead (Pb) as a solid solution.

Moreover, the feature of the barium titanate-based semiconductor porcelain of the third invention is that the - part of barium (Ba) is 0.001 to 0.1.
at percent magnesium (Mg) and from 0.01 to
5.0at percent percent lead (Pb) was simultaneously dissolved in solid solution.

[Function] In the first invention, magnesium (Mg) of o, oot ~ O, la [perset], which is substituted with the - part of barium (B a) and dissolved, is Suppresses resistance fluctuations in barium titanate semiconductor ceramics.

In the second invention, lead (pb) of 0.01 to 5.0 at percent, which is substituted with - part of barium (B a) and dissolved, is a barium titanate based material based on temperature changes in the usage environment. Suppresses fluctuations in resistance value of semiconductor porcelain.

In the third invention, magnesium (Mg) of 0,001 to 0.1al percent and 0-01 to 5.0at substituted with - part of barium (Ba) and dissolved as solid solution.
% lead (:Pb) suppresses fluctuations in the resistance value of barium titanate-based semiconductor porcelain due to temperature changes in the usage environment.

[Embodiment J of the invention Examples of the first invention will be described below.

Barium titanate-based semiconductor porcelain is barium titanate (
BaTi03), or barium titanate (BaTi03), or barium titanate (BaTi
03) to which strontium (Sr), tin (Sn), or zirconium (Zr) is added to control the Curie point.・Ntrium (Y), niobium (Nb), antimony (Sb), bismuth (Bi,
) selected from the group at least l! ! It has a composition that is added as a micro-isthmus additive for semiconductor formation.

Furthermore, the barium titanate-based semiconductor ceramic has a composition in which 11 additives are added in order to improve the positive resistance-temperature characteristic and steepen the resistance-temperature gradient. These additives include manganese (Mn), silicon (St
), aluminum (A1), titanium (TI), and other oxides.

The barium titanate semiconductor ceramic is characterized in that a portion of barium (Ba) is substituted with 0-001 to 0.1 at percent magnesium (Mg) as a solid solution. The reason for limiting the composition to the above is that below the above lower limit, no improvement in the temperature characteristic ratio is observed, and below the upper limit, the resistivity at room temperature becomes significantly high and it is difficult to obtain a good sintered body. This is to become.

Therefore, in order to mold barium titanate-based semiconductor porcelain having the above composition, BaC0z, Src03MgCO3
, Y2 03 , TiO2, MnO, Si02
, Zr0z, and 5b203 are weighed, mixed and pulverized, dried, held at a temperature of approximately 1100 degrees C for 2 hours, and pre-calcined. After the pre-calcination, they are pulverized and dried again to form polyvinyl alcohol. added as a binder, 15
Granulate to a particle size of about 0 mesh. After granulation, a pressure of about 1000 kg/cml was applied using a press machine to make the pellets have a diameter of 10 mm.

Shaped into a disk with a thickness of 3 mm and heated in an electric furnace at a temperature of approximately 1370°C.
The barium titanate semiconductor porcelain is fired by raising the temperature to 15°C and sintering for about 1 hour.

Moreover, the barium titanate-based semiconductor/a in the second invention
The feature of the container is that a part of barium (B a) is
．． Substituted with 0at percent lead (Pb), [,ffl
It is made by melting. The reason for limiting the composition to the above is that below the lower limit value, no improvement in the temperature characteristic ratio is observed, and below the upper limit value, the specific resistance at room temperature becomes significantly high and a good sintered body cannot be obtained. This is because it becomes difficult. Therefore, in order to form the barium titanate-based semiconductor porcelain according to the second invention, BaCOx,
5rC03, PbO, Y203, rr02, M
Such a barium titanate type semiconductor ceramic can be obtained by weighing a predetermined amount of nO, Sio2 and ZrO2, 5b203 and then performing the same molding process as above.

Further, the feature of the barium titanate-based semiconductor porcelain in the third invention is that a portion of barium (Ba) is 1°, 001~O
, lat percent magnesium (Mg) and 0.0
It is a solid solution substituted with 1 to 0.1 aL percent of lead (Pb). The reason for limiting the composition to the above is that no improvement in temperature characteristic ratio is observed below the lower limit value.
In addition, if it exceeds the above-mentioned upper limit, the specific resistance at room temperature becomes extremely high, and it becomes difficult to obtain a good sintered body. Therefore, in order to mold the barium titanate semiconductor porcelain according to the third invention, BaCO3, MgC0=
, SrCO3, PbO, Y; IO2, TiO2, M
After weighing a predetermined amount of nO, 5iOz and Zr02Sb20t, a barium titanate type semiconductor ceramic can be obtained by performing the same molding process as above.

As described above, a positive temperature coefficient thermistor is formed by molding the barium titanate semiconductor ceramic into a disc and attaching electrodes showing ohmic positive contact to both sides of the barium titanate semiconductor ceramic.

Using such a positive temperature coefficient thermistor, the room temperature specific resistance value ρ (25℃) and the temperature characteristic ratio R (-20℃ )/R(min), R(60℃)/R(
min) is shown in Table 1, and a characteristic diagram of temperature-specific resistance value is shown in the drawing.

In the drawings, solid lines indicate this embodiment, and broken lines indicate the next embodiment.

As mentioned above, by replacing a part of barium (Ba) with magnesium (Mg) or lead (Pb), or with magnesium (Mg) and lead (Pb) at the same time, as shown in the drawing, <The NT in the NTC area indicating the Rmin value
It became possible to suppress C characteristics. In other words, it was possible to obtain a PTC thermistor with little variation in resistance over a wide temperature range of approximately ±40 degrees Celsius with the Rmin value as the boundary. Specifically, the conventional value of 1.30 or more was suppressed to 1.20 or less.

Normally, the operating environment temperature in Japan is -20℃ to 60℃, so within this temperature range the temperature characteristic ratio [R(-2
0℃)/R(min), R(60'C)/
R(m f n) ] is small, in other words, a PTC thermistor with small resistance fluctuation can be obtained.

In this way, within the range of temperature changes in the usage environment, even if the environmental temperature changes, the resistance value of the thermistor does not change as much as in the conventional example, so the communication line.

It is possible to provide a highly reliable PTC thermistor that is required as a component of a protector used to prevent lightning surges and cross-contact with commercial power sources.

[Effects of the Invention] The above-described barium titanate-based semiconductor porcelain can be used by substituting a part of the barium with magnesium, by replacing it with solid solution, by replacing it with lead, or by replacing it with magnesium and lead at the same time. Since changes in resistance due to temperature changes can be suppressed within the temperature range of the environment, when this barium titanate semiconductor Fj 1st base is used as a component of a communication line protector, the reliability of this communication line protector can be improved. can be directed to -E.

[Brief explanation of the drawing]

Table 1 shows the main component set r of barium titanate-based semiconductor porcelain.
The table and drawings compare the conventional example and this example in terms of & ratio, resistivity value at 25°C, and temperature characteristic ratio, and the drawing compares the conventional example and this example in terms of fluctuations in resistivity value based on temperature changes. It is a line diagram. The column for the brief explanation of the drawings in the statement of contents of the amended procedural amendment was amended in 1983 as follows:
Corrected in December.

Claims (3)

[Claims] (1) BaTiO3 (barium titanate) or BaT
Mainly iO3 (barium titanate), and strontium (Sr) and tin (Sn) for controlling the Curie point.
Or the rare earth element yttrium (Y) is added to a barium titanate ceramic composition containing zirconium (Zr).
, niobium (Nb), antimony (Sb), bismuth (B
i) Barium titanate-based semiconductor porcelain containing at least one kind selected from the group as a trace additive for semiconductor formation and a plurality of sub-additives for improving PTC characteristics, A barium titanate-based semiconductor porcelain characterized in that a part of barium (Ba) is substituted with 0.001 to 0.1 at percent magnesium (Mg) as a solid solution. (2) BaTiO3 (barium titanate) or BaT
Mainly iO3 (barium titanate), and strontium (Sr) and tin (Sn) for controlling the Curie point.
Or the rare earth element yttrium (Y) is added to barium titanate ceramic compositions containing zirconium (Zr).
, niobium (Nb), antimony (Sb), bismuth (B
i) Barium titanate-based semiconductor porcelain containing at least one selected from the group as a trace additive for semiconducting and further containing a plurality of sub-additives for improving PTC characteristics, A barium titanate-based semiconductor porcelain characterized in that a portion of barium (Ba) is substituted with 0.01 to 5.0 at percent lead (Pb) as a solid solution. (3) BaTiO3 (barium titanate) or BaT
Mainly iO3 (barium titanate), and strontium (Sr) and tin (Sn) for controlling the Curie point.
Or the rare earth element yttrium (Y) is added to barium titanate ceramic compositions containing zirconium (Zr).
, niobium (Nb), antimony (Sb), bismuth (B
i) Barium titanate-based semiconductor porcelain containing at least one selected from the group as a trace additive for semiconducting and further containing a plurality of sub-additives for improving PTC characteristics, Part of barium (Ba) is 0.001-0.1at percent magnesium (Mg) and 0.01-5.0a
A barium titanate-based semiconductor porcelain characterized by simultaneous solid solution substitution with t percent of lead (Pb).