JPH04132201A - Positive temperature coefficient thermistor - Google Patents

Abstract

PURPOSE:To obtain an extremely low resistivity at a room-temperature region by a method wherein one or more each of a Ba site, a Ti site and an O site of BaTiO3 as a main component are selected from specific element groups and the valency of three elements of Ba, Ti and O is controlled simultaneously. CONSTITUTION:SrTiO3 and CaTiO3 are added to BaTiO3 as a main component. One or more elements are selected respectively from a group of (La<+3>, Sb, Y<+3> and Dy<+3>) for a Ba site, from a group of (Nb<+5>, Ta<+6>, V<+6> and Mn<+4>) for a Ti site and from a group of (F<-1> and Cl<-1>) for an O site. They are added in 0.05 to 0.2mol%, the valency of three elements for the Ba site (Ba, Sr and Cr), the Ti site and the O site is controlled simultaneously. For example, the temperature of a mixed powder of BaTiO3, SrTiO3 CaTiO3, TiO2, MnO2, Sb2O3, Nb2O5 and CaF2 is raised in the air and the temperature is kept. The temperature is lowered; and the mixed powder is baked. One part of the Ba site (Ba, Sr and Ca) is replaced by trivalent (Sb<+3>); one part of the Ti site is replaced by (Nb<+5> and Mn<+4>); and one part of the O site is replaced by (Fe<-1>). It is possible to obtain a positive temperature coefficient thermistor whose resistivity is at 5OMEGA.cm or lower, whose psi>3.0 and whose withstand voltage is at 100 to 300V/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a positive temperature coefficient thermistor having extremely low resistivity at room temperature.

Conventional technology A positive temperature coefficient thermistor whose resistance value increases rapidly when the Curie temperature is exceeded is mainly composed of B1TiOs and Sr.
By mixing T t Os and PbTi0-,! ! ! niB
By replacing the a site and Ti site with the elements of each dopant agent, specific resistance ρ > 5Ω・C1, ma ≥ 5 (ma: logarithmic ratio of room temperature resistance and Curie temperature resistance), withstand voltage 100 to 300 V
/ cm is popular.

What the invention seeks to solve: In order to lower the resistivity in the normal temperature range, the main component BaTi
The present inventor has already developed a valence control method in which three elements of Os or three elements are partially replaced with other elements at the same time (
Utility Application No. 1-258518). Three element valence - ■ Selection and blending ratio of dopant agents are determined, and ρ〈5Ω・C-
3 positive characteristic thermistors are provided.

Means to solve the problem 5rTiOa and C are added to B a T i O * which is the main component.
Add aTiO3 and convert Ba sites (La", Sb, Y"
, Dy"> group, Ti sites are (Nb", Ta-
', V"Si" + Mu") group, the 0 site is (F-
', CII) #, and add 0.005 to 0.2% of these elements to form Ba sites (Ba, Sr.

The valence of the three elements Ca), Ti site, and 0 site is controlled simultaneously.

Because the element of the dopant agent for controlling the valence of the action partially replaces the element at each site, the resistivity is less than 5Ω・elf.
3.0. A positive temperature coefficient thermistor having a withstand voltage of 100 to 300 V/c- was obtained.

Example B: 89 mol % of a T i Om (f J'nic acid).

7 mol % of S r TiOs and 3 mol % of CaTiOs.

0.6 mol% of Ti 0 m, 0.08 moJ of MnO2
death%.

0.10 mol% of Sb*Om and 0.05 mol% of Nb2O strips.

A mixed powder containing 0.04 mol% of CaFs was heated to 18 mol% in air.
Raise the temperature at a base rate of 0°C/H and keep it at 1360°C for 20 minutes. and.

The temperature is lowered at a base rate of 300°C/H and fired. ρ=3. O
Ω・Cm, Ma>3. A positive temperature coefficient thermistor having the following characteristics was obtained: a temperature of 98° C. and a working voltage of 35 V.

Part of the Ba site (Ba, Sr, Ca) is replaced by trivalent (Sb+S), and part of the Ti site is replaced by (Sb+S).
Nb″1゜Mn″4) is substituted, and (F
-') is replaced.

As another example, BaTiOs was added to 8L 0%J%
.

10.0 mol% S r T j Os, CaTiOs
2.0%)%, TiOs 0.6 mol%, Mn0t
0.08 mol%, S breath 0, 0.01 mol%, Dy2
0m 0.1 mol%, TatOh 0.05 mol%, S
A mixed powder containing 0.03 mol % of F is fired under the same conditions as above.

Part of the Ba site is replaced by (Dy""), part of the Ti site is replaced by (Ta", Si", Mn"4), and part of the 0 site is replaced by (F-ri). The characteristics of this positive temperature coefficient thermistor were ρ=3.5Ω·Cm, m≧3.0, Curie temperature 94° C., and working voltage 35V.

Effects of the Invention In particular, the present invention has the following advantages:
5rTj Os and CaTjOt were added to the Ba site (La”.

sb", y"", Dy") group, the Ti site is (Nb
``1Ta''+V''+S+''+Mn''4) One or more elements are selected from each of the O site and the (F-', CI-') group, and Ba.

Since the valences of the three elements Ti and O are controlled simultaneously, it is possible to provide a positive temperature coefficient thermistor having a resistivity of 5Ω·Cm or less and a characteristic of M>3.0.

Claims (2)

[Claims] (1). The Ba site of BaTiO_3, which is the main component, is (La^+^1, Sb^+^2, Y^+^3, Dy^+
From the ^2) group, the Ti site was (Nb^+^5, Ta^+
From the ^5, Si^+^4, V^+^5, Mn^+^4) group, the O site from the (F^-^1, Cl^-^1) group,
A positive characteristic thermistor that simultaneously controls the valence of three elements, Ba, Ti, and O, by selecting one or more of each element. 2. The main component BaTiO_3 is SrTiO_3 and C.
Add aTiO_3 and Ba site (La^+^3, S
b^+^3, Y^+^3, Dy^+^3) group, Ti
Site (Nb^+^6, Ta^+^5, V^+^5,
From the Si^+^4, Mn^+^4) group, the O site is (F
Select one or more elements from each of the groups ^-^1, Cl^-^1) and add 0.005 to 0.20 mol% of these to control the valence of the three elements Ba, Ti, and O at the same time. , Positive characteristic thermistor.