Effect of heat treatment on performance of high-temperature thermistor LaCrO₃

In this study, pure LaCrO₃ ceramic as the negative temperature coefficient (NTC) thermistors were investigated. NTC LaCrO₃ powder with an average particle size of 80 nm was prepared using the sol–gel method, and LaCrO₃ ceramic samples with a relative density spanning from 92.8 to 95.6% were prepared using spark plasma sintering (SPS) at 1450, 1500, and 1600 °C. The LaCrO₃ samples were then heat-treated at 1300 °C in an air atmosphere for 2 h. Before heat treatment, the values of room temperature resistivity were between 1.34 × 10⁹ and 2.59 × 10⁹ Ω·cm; material constant between 4418 and 4575 K; and activation energy between 0.6099 and 0.6316 eV. After heat treatment, the resistivity was from 2.19 × 10⁵ to 1.54 × 10⁶ Ω·cm, material constant from 2539 to 2808 K, and activation energy from 0.3505 to 0.3876 eV. This combination of properties renders pure LaCrO3 materials an excellent candidate system for application as NTC thermistors in the high-temperature range of 200–800 °C.