JPS63316402A - Oxide semiconductor for thermistor use - Google Patents

Abstract

PURPOSE:To keep a B constant nearly definite and to change only a specific resistance value by a method wherein ZrO2 as a high-resistance oxide is compounded to an Mn-Ni-Cr-related oxide semiconductor which is composed mainly of Mn. CONSTITUTION:5-25atomic% zirconium is added externally to a total of 100 atomic% of a composition where manganese as a main component, 15-20atomic% nickel and 1-5atomic% chromium are contained as metal elements. For this composition the amount of ZrO2 is changed variously. By this setup, because an oxide semiconductor for thermistor use keeps a B constant nearly definite and changes only its specific resistance value, it is possible to form a desired shape of a thermistor device with a desired thermistor characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an oxide semiconductor for a thermistor, which has a negative temperature coefficient of resistance and can be used as a temperature sensor.

BACKGROUND OF THE INVENTION Conventionally, the oxide semiconductor for a thermistor of the present invention has a composition composed of an Mn--Go based oxide semiconductor having a spinel structure and containing Ni and Cu, which are resistance value controlling atoms.

Problem to be Solved by the Invention The resistance value Rτ of a thermistor element at a certain temperature T is the specific resistance ρ! of the oxide semiconductor for the thermistor that constitutes the thermistor element. Therefore, RT = (t/S) Xρ! It is determined by

Here, S is the electrode area and t is the distance between the electrodes. Therefore, if you want to change only the resistance value R1 at a certain temperature T without changing the shape of the boomister element or the B constant, it is necessary to change the specific resistance ρ〒ft of the oxide semiconductor for the boomister to match it.However, the conventional composition described above Now, N1 and Cuji
If the resistivity is changed by changing the resistivity, the B constant also changes, so there is a problem in that it is not possible to keep the B constant of the oxide semiconductor for thermistor almost constant and change only the resistivity completely. solves all of these problems and has the same B constant. An object of the present invention is to provide an oxide semiconductor for a thermistor having a specific resistance value of 100%.

Means to Solve the Problem In order to solve this problem, the present invention uses an oxide semiconductor for a thermistor as a spinel (1n-N-Or based oxide semiconductor mainly composed of Mn'z). The composition is made by combining ZrO□, which is a high resistance oxide, and further changing ZrO2 into four pillars.

Function: Due to this structure, the oxide semiconductor for the boomister is B
Since the constant can be kept substantially constant and only the specific resistance can be changed, a thermistor element having a desired shape and having desired boomister characteristics can be obtained.

Example An embodiment of the present invention will be described below.

As a preliminary study, we determined the composition range of the Mn-N-Or based oxide semiconductor. As is well known, the 0Mn504 oxide semiconductor forms a spinel structure, and there are is arranged by Mn ions, which causes the spinel structure to be distorted into a tetragonal structure.

Considering the positional selection energy of the ions that can be placed with the Mn ions in this B-phyto, Ni2+ ions and Cr ions are listed. When these elements were extracted into αΣ in the form of oxides and examined by X-ray diffraction, N
When i was 15 atomic % or more and Or was 1.0 atomic % or more, this spinel structure became a cubic single phase.

The table below shows changes in resistance values due to heat treatment of samples with typical compositions and their crystal structures.

The inventor of the present invention believes that this change in resistance value is due to the crystal structure, and therefore all compositions containing less than 15 atomic % of Ni and 1.0 atomic % of Cr and less than 9 c of Cr are outside the scope of the claims of the present invention. Also, N12o
NiO precipitates in a range exceeding atomic %, and Cr s
If the amount exceeds atomic percent, the sintered body becomes porous and unstable in terms of stain resistance, and therefore is outside the scope of the claims of the present invention.

In preparation for the above preliminary study, samples having the compositions shown in the table below were prepared.

('*: zr is an external addition) To illustrate the manufacturing process, these blended compositions are wet mixed in a ball mill, the slurry is dried and calcined at 800'C, and the calcined product is wet-pulverized again in a ball mill. After drying the obtained slurry, polyvinyl alcohol was added and mixed as a total binder, and a diameter of 12ts; γ
It was molded into a 2 MM disk shape. This molded body (i-1
Calcined in air at 300'C for 2 hours. A silver electrode was provided on this disc-shaped sintered body. The specific resistance value of the boomister manufactured in this way at 26°C and 6°C and 26°C
The diagram shows the change in B constant due to Zr fm at 0°C.

As is clear from the drawings, by changing the amount of Zr in the oxide semiconductor according to the present invention, the B constant can be kept almost constant and only the specific resistance can be changed. In addition, Zr
If the Zr content is less than 5 atomic %, the effect of increasing the specific resistance is not significant, and if the Zr content exceeds 26 atomic %, the change in the B constant becomes noticeable, so this is outside the scope of the claims of the present invention.

Effects of the Invention As described above, according to the present invention, la containing Mn as a main component
By using an oxide semiconductor for a thermistor that is a combination of an n-Ni-Or-based oxide semiconductor and ZrO□, which is a high-resistance oxide, the B constant can be kept almost constant and only the specific resistance can be changed. The present invention can greatly contribute to providing a thermistor element having a desired shape and having desired thermistor characteristics.

[Brief explanation of drawings]

The figure is a graph illustrating the change in specific resistance and B constant depending on the Zr content of the oxide semiconductor for thermistor obtained by the present invention0 Name of agent Patent attorney Toshio Nakao and 1 other person5
10 75 fi! Z
r (at,%)

Claims (1)

[Claims] As a metal element, manganese is the main component, and nickel 15
~20 at%, chromium 1-5 at%, total 100
Zirconium is 5 to 5% in terms of the composition containing atomic%.
An oxide semiconductor for a thermistor, characterized by containing 25 at%.