CaTiO3 nano ceramic for NTCR thermistor based sensor application

It is possible to fabricate highly sensitive NTCR (negative temperature coefficient of resistance) thermistor using nano crystalline CaTiO3 synthesized by high energy ball milling. Disc shaped green pellets were prepared and effects of sintering on the disc pellets were studied as thermistor by sintering the samples at 1000 °C, 1100 °C and 1200 °C. The as-prepared samples were characterized by X-ray diffraction (XRD), impedance analysis and electrical measurement. The resistivity of the prepared samples varies predictably with temperature: this makes them promising material for temperature sensor. The experimental results prove that nano crystalline CaTiO3 ceramic is one kind of thermistor with exponential negative temperature coefficient of resistance in the temperature range of 300–500 °C. The samples have the advantages of rapid response, high sensitivity and capability to withstand thermal surges over the temperature range of 300–500 °C. Resistance-temperature characteristics are described by thermistor equation with thermistor constant around 4003 K to 10795 K and thermal coefficient of resistance α around ∼1%/°C to ∼13%/°C. The activation energy is in the range of 0.34–0.93 eV. The observed thermistor parameters are found to be comparable with many of the known thermistor materials. This suggests that the electrical properties can be adjusted to desirable values by controlling the temperature parameter. The influence of fabrication process of disc thermistor and electrical properties are discussed. The study shows the potential of nano crystalline CaTiO3 to act as an NTCR material for thermistor applications.