JPS62108503A - Oxide semiconductor for thermistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an oxide semiconductor for a thermistor having a negative temperature coefficient of resistance and which can be used as a temperature sensor in the range of 160° C. to SOO° C.

Conventional Art The well-known Mn-Co-Ni-Cu oxide thermistor material has been mainly used as a general-purpose disk-type thermistor, but due to large fluctuations in resistance when used at high temperatures, It cannot be used at high temperatures exceeding 300°C, and has been used at temperatures below 300°C. On the other hand, as a material that can be used at high temperatures of 700 to 100oC, stabilized diA/Koni7 (Zr02-Y2O2,
Zr02-CaO, etc.), Mg--Al-Cr-Fe oxide spinel systems, etc. have been developed (Japanese Patent Publication No. 48-705
Publication No. 49-63995, Japanese Patent Publication No. 1987-63995
33756). - Problems to be solved by the invention However, these oxide materials also have a sintering temperature of 1600°C.
The temperature must be higher than
600° C.), it could not be fired.

Furthermore, even in the case of sintered bodies of these oxides, the resistance value changes significantly over time, and even those that are extremely stable have a resistance value of 10% (10%).
000 hours), and there was a problem in stability over time.

In addition, the demand for a thermistor with excellent stability at 200 to 500°C has increased from the sensor market, and the thermistor constant (Mn -N i -A , (NixMg, Zn
,) Mn204 spinel system: Japanese Patent Application Laid-open No. 1988-887°C, (Nip Coq Fer Alt
r Mn 004 spinel type: JP-A-6-88702
(e.g., Publications No. 1, etc.) have been proposed, but they are still in the evaluation stage.

In response to the above request, the present inventors also discovered Mn-Ni-Cr
-Zr oxide system (Japanese Patent Application No. 58-131265) has been proposed.

The present invention has been made in view of the above-mentioned problems, particularly regarding resistance stability over time under high temperatures, and has three objectives:
It is an object of the present invention to provide an oxide semiconductor for a thermistor that exhibits a suitable resistance value even at 00°C to 500°C and can be stably used.

Means for Solving the Problems In order to achieve the above object, the oxide semiconductor for thermistor of the present invention is made of a sintered mixture of metal oxides, and the metal element thereof is manganese (Mn) of 60.0 to 60.0. 98.5 atomic% Nickel k (N i ) 0.1-5.0 atomic%
, chromium (Cr) 0.3 to S, O atomic %, rank y (L
a) 0.2-5.0 atoms Ti and zirconium (Zr)
It contains five types of atoms ranging from 0.6 to 28.0 atoms, for a total of 100 atoms.

Furthermore, for every 100 atoms in the above composition, the outer layer may contain 2.0 atoms or less of silicon (Si) (excluding O atoms).

Function: With this configuration, it is possible to obtain a thermistor that exhibits a suitable resistance value in the temperature range of 300° C. to SOO° C. and has excellent resistance stability over time. Here, when stabilized zirconia containing La 203 as a solid solution is used, the ceramic microstructure is such that zirconia stably forms at the joint of the spinel crystal, compared to the Mn-Ni-Cr spinel crystal that exhibits high resistance. existence, which improves the compactness of the ceramic. Here, the grain size of zirconia is smaller than that of spinel crystal. Moreover, the specific resistance can be adjusted by adjusting the content of stabilized zirconia, and a desired resistance value can be obtained. Furthermore, compared to the case where zirconium is added alone, stabilized zirconia promotes densification and exhibits improved properties against thermal shock, etc., as described above.

Example Examples of the present invention will be described below.

Commercially available raw materials Mn CO3, N i O, Cr 203 and ZrO2 containing La 203 were blended to have the respective atomic compositions as shown in the table below. To illustrate the thermistor manufacturing process, these blended compositions were wet mixed in a ball mill, the slurry was dried and calcined at 1000° C., and the calcined product was wet-pulverized and mixed again in a ball mill. After drying the slurry thus obtained,
Polyvinyl alcohol is added and mixed as a binder, and a required amount is taken and molded into a block of 30ffψ×15fft. Then, this molded body was fired in air at 15 oot for 2 hours. From the block thus obtained, slice,
A Ueno film having a thickness of 160 to 400 μm is removed by polishing, and a platinum electrode is provided by screen printing.

This electrode-applied element is cut into a chip of a desired size. The element is sealed in a glass tube in a neutral gas atmosphere such as argon gas or in air, and hermetically isolated from the outside air. Lead wire terminals vary depending on the operating temperature.
A slug lead such as a dumet wire or a conical wire is used.This glass-encapsulated thermistor was left in air at 500°C, and the resistance change after 100 hours was measured.The initial characteristics were the ratio at 25°C. The resistance and thermistor constant as a glass-encapsulated thermistor are also shown.

Among these, the thermistor constant B was determined from the resistance values at two points measured at 300°C and SOO°C. Note that the element dimensions were 400 μm x 400 μm x 300 μm.

In the above table, all of the comparative samples had a resistance change rate over time at 500° C. of more than 5% and lacked practical stability, so they were excluded from the scope of the present invention. On the other hand, the samples within the scope of the present invention all had resistance change rates over time at SOO° C. of ε or less, indicating that the stability was improved.

The samples used this time were dry-molded and fired, but bead-type elements may also be used, and there are no restrictions on the element manufacturing method.

In the examples of the present invention, zirconia boulders were used for mixing raw materials and pulverizing and mixing calcined products.

As a result of elemental analysis of the sample (sintered body) of the above example, the amount of Zr mixed in was 100% of the thermistor constituent elements.
The number of O and S atoms was less than that of atoms. In addition, when agate boulders were used, the amount of Si mixed was less than one atom. Among the samples shown in the table, all the samples containing St were obtained using zirconia boulders.

Further, all Zr used in this example was obtained by reacting with La, that is, lanthanum oxide stabilized zirconia. As a general rule, the stabilized zirconia was commercially available or obtained as a sample from the manufacturer, but some was synthesized from oxalate and used.

Effects of the Invention As described above, the oxide semiconductor for a thermistor according to the present invention is made of a sintered mixture of metal oxides, and its constituent metal elements include 60.0 to 98.6 at% of Mn and 60.0 to 98.6 at% of Ni.
O, 1 to 5.0 atomic percent, Cro, 3 to 5.0 atomic percent,
L a O, 2-5 D atoms and Zr O, 6-2
Contains 5 types of 8.0 atomic mass with a total of 100 atomic mass, so it has excellent characteristics over time even in the range of 300°C to SOO°C, and is suitable for temperature measurement where high reliability is required at medium and high temperatures. most suitable for That is, it can be expected to contribute to fields of application such as temperature control in microwave ovens and oil burners, for example. In addition to the above-mentioned constituent metal elements, Si is added on the outside to 2.0 atoms or less (not including 0 atoms).
When it is contained, it exhibits a sintering accelerating effect, and dense ceramics can be obtained.

Claims (2)

[Claims] (1) Consists of a sintered mixture of metal oxides, the constituent metal elements of which are manganese 60.0 to 98.5 at%, nickel 0.1 to 5.0 at%, and chromium 0.3 to 6.0 An oxide semiconductor for a thermistor, comprising a total of 100 atom % of six types: 0.2 to 5.0 atom % of lanthanum, and 0.6 to 28.0 atom % of zirconium. (2) Consisting of a sintered mixture of metal oxides, its constituent metal elements include manganese 60.0 to 98.5 at%, nickel 0.1 to 5.0 at%, and chromium 0.3 to 6.0 Contains a total of 100 at% of 5 types, 0.2 to 5.0 at% of lanthanum and 0.6 to 28.0 at% of zirconium, and 2.0 at% of silicon relative to the constituent metal elements. An oxide semiconductor for a thermistor, characterized in that it contains atomic % or less (excluding 0 atomic %).