JPS6059186B2 - Thermistor composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel thermistor composition that is stable and has low specific resistance.

As a thermistor material whose resistance value has a negative slope with respect to temperature, two or more types of oxides such as Mn, Co, Ni, Cu, Fe, Al, and Si are mixed, heat-treated at 900 to 1300°C, and baked. Composite oxides are well known.

Among these, complex oxides containing Cu have a specific resistance of 100
Some are as small as Ω-α or less, and are used as low-resistance thermistor materials. However, this thermistor element made of a material containing Cu has a resistance value change of +10% or more and lacks stability, so it cannot be used for highly accurate temperature detection or as a temperature compensation element. Therefore, there is a need for a thermistor material with low specific resistance and excellent stability. An object of the present invention is to provide a thermistor material with low resistance and particularly excellent stability.

The present invention provides (a) a mixture of oxides of Mn, Co, and Ir;
or (b) the oxide of Mn9Co91r further contains Fe,
A mixture of either one of the Ni oxides is crushed,
The composite oxide obtained by firing is characterized in that 44% of the total amount of metal components in the composite oxide are Ir atoms.

The reason why the Ir content is set to 44% atoms is that if the material composition exceeds this value, the temperature change in resistance value, that is, the thermistor constant becomes small, and the material does not exhibit the characteristics as a thermistor.

Note that the composition that does not contain Ir is a conventional thermistor material. The present invention will be explained below with reference to Examples. Example 1 MnO.

, CoO, Ir0. was used as a starting raw material powder, and a total weight of 50 Da was weighed out so as to have the composition shown in Table 1. These powders are mixed by shaking for 4 hours using an agate mortar. This mixed powder was placed in an aluminum crucible and heat treated at 900°C for 2 hours. Next, it was shaken and crushed for 4 hours in a Meno J-made mortar, and 12.0
A pellet of φ×3, (y' was created. This pellet was heat-treated at 1250°C for 2 hours to create a ceramic. Electrodes were formed on both sides of this ceramic using conductive paint, and the thermistor characteristics were measured. , 150℃,
Its stability was investigated by leaving it at a high temperature for 200 hours.
However, sample No. in Table 1. 1 is a conventionally well-known thermistor material and is listed as a reference. No. 1 in Table 1. Those containing 44% of Ir atoms from 2 to 12 are NO. Compared to 1, it has a lower resistivity and better stability. Note that NO. containing 46% Ir atoms. 13 has a thermistor constant smaller than 500K and is less useful as a thermistor. Example 2 Using Mn304, c0304, N10, and Ir02 as starting materials, a ceramic having the composition shown in Table 2 was produced using the same manufacturing method as in Example 1, and its thermistor characteristics and stability were investigated.

Stability was evaluated by standing at a high temperature of 150°C for 200 hours.
However, Sample 1 in Table 2 is a conventionally well-known thermistor material and is listed as a reference.

No. in Table 2. Those containing up to 44% of Ir atoms from 2 to 15 are NO. The resistivity is lower and the stability is better than that of a material that does not contain Ir. In addition, NO. 46 of l6
% atoms, the thermistor constant becomes smaller than 500K and the thermistor is less useful. Example 3 Using Mn02, c0304, Fe203, and Ir02 as starting materials, ceramics having the composition shown in Table 3 were produced by the same manufacturing method as in Example 1, and their thermistor characteristics and stability were investigated.

Stability was evaluated by standing at a high temperature of 150° C. for 20 hours. However, Sample 1 in Table 3 is a conventionally well-known thermistor material and is listed as a reference.

Claims (1)

[Claims] 1. (a) A mixture of oxides of Mn, Co, and Ir, or (b) a mixture of oxides of Mn, Co, and Ir with either one of oxides of Fe or Ni is crushed and fired. A thermistor composition characterized in that up to 44% of atoms of the metal component in the composite oxide are Ir.