New high temperature negative temperature coefficient thermistors in Mg0.5Mn0.5AlFeO4 ceramics

For high temperature thermistor applications, the MgAl2O4 exhibits poor conductivity and requires high sintering temperature for ceramic densification. In this study, we have reported on the preparation and characterization of spinel Mg0.5Mn0.5AlFeO4 ceramics by solid solution modification. The resultant ceramics exhibit a combination of high temperature stability and semi-conductivity, which are the characteristics of MgAl2O4 and MnFe2O4. The material has a moderate thermistor constant, which is in favor of application at high temperatures and a wide temperature range. The electrical conductivity is due to the small-polaron hopping in different valence states of manganese and iron ions. Our findings demonstrate a promising approach to extend the applicability of spinel ceramics for high temperature thermistors.