NTC (Negative Temperature Coefficient) refers to the thermistor phenomenon and material with a negative temperature coefficient whose resistance decreases exponentially with temperature rise. The material is a semiconductor ceramic made by fully mixing, molding, and sintering two or more metal oxides such as manganese, copper, silicon, cobalt, iron, nickel, and zinc. It can be made into a material with a negative temperature coefficient. (NTC) thermistor. Its resistivity and material constants vary with material composition ratio, sintering atmosphere, sintering temperature and structural state. There are also non-oxide NTC thermistor materials represented by silicon carbide, tin selenide, and tantalum nitride.

NTC heat-sensitive semiconducting ceramics are mostly oxide ceramics with a spinel structure or other structures, which have a negative temperature coefficient. The resistivity of the ceramic grain itself changes due to temperature changes, which is determined by the characteristics of semiconductors.

The development of NTC thermistors has taken a long time. In 1834, scientists discovered for the first time that silver sulfide has a negative temperature coefficient. In 1930, scientists discovered that cuprous oxide-copper oxide also has a negative temperature coefficient, and it was successfully used in the temperature compensation circuit of aviation instruments. Subsequently, due to the continuous development of transistor technology, research on thermistors has made significant progress. In 1960, the N1C thermistor was developed. NTC thermistors are widely used in temperature measurement, temperature control, temperature compensation, etc. Since the resistance value of the thermistor changes with the change of temperature, the indication of the gauge connected between the diagonals of the bridge changes accordingly. This is how a thermistor thermometer works.