These materials include single crystal semiconductors, polycrystalline semiconductors, glass semiconductors , organic semiconductors, and metal oxides. They all have a very large resistance temperature coefficient and high turtle resistance, and the sensitivity of the sensors made of them is quite high. According to the resistance temperature coefficient can also be divided into negative resistance temperature coefficient materials and positive resistance temperature coefficient materials. In a limited temperature range, the negative resistance temperature coefficient material a can reach -6*10-2/°C, positive resistance temperature coefficient material a can be as high as -60*10-2/°C or more. For example, barium drinking acid ceramic is an ideal semiconductor material with positive resistance temperature coefficient.

Both of these materials are widely used in temperature measurement, temperature control, temperature complementary transients, switching circuits, overload protection and time delay, such as making thermistor thermometers, thermistor switches and thermistor thermometers, thermistor switches and thermistor delay relays with subs, respectively. These materials have a narrow temperature measurement range and poor uniformity because of the exponential relationship between resistance and flow.

Metal thermistor materials

Such materials as RTD temperature measurement, current limiter and automatic thermostatic heating elements are more widely used. Such as platinum resistance thermometer, nickel resistance thermometer, copper resistance thermometer, etc. Among them, platinum side temperature sensors in a variety of media (including corrosive media), showing obvious high precision and high stability characteristics. However, their wide application is somewhat limited due to the scarcity and high price of platinum. Copper temperature sensors are cheaper, but long-term use in corrosive media can lead to significant changes in static characteristics and resistance values.

Recently, it has been reported that copper temperature sensors can be used in the temperature range of -60~180℃ in air medium. However, in order to measure the temperature in -60~180℃ for a long time and in 250℃ for a short time, the nickel temperature sensor is widely used in foreign countries, and nickel is considered a more ideal material because they have high sensitivity, satisfactory reproducibility and stability.

Alloy thermistor materials

Alloy thermistor materials are also known as thermistor alloys. This alloy has a high resistivity and is sensitive to changes in resistance with temperature, making it a good material for manufacturing temperature sensitive sensors.

The performance requirements for thermistor alloys used as temperature sensitive sensors are as follows.

(1) Large enough resistivity.

(2) Considerably high resistance temperature coefficient.

(3) With a coefficient of linear expansion close to that of the experimental material.

(4) Small strain sensitivity factor.

(5) The resistance temperature curve should have good repeatability when heating and cooling in the working temperature range.