Electrical characterization of strontium ferrite composition SrFeO_2,97 how to use thermistor

The ferrites have attracted great interest for applications in electrical machines such as permanent magnets, temperature sensors or protection against short circuits or overloads. This work aims at the synthesis of strontium ferrite SrFeO_2,97, for application as PTC and NTC thermistor. The samples obtained with less milling time and sintered at low temperature had higher electrical conductivity with high porosity in the microstructure, while at higher temperature and longer time of grinding, the samples had higher conductivity, and large grains and pores intergranular microstructure. According to the results of the electrical conductivity of strontium ferrite varied from 22.9 (Ωcm) ^-1 to 78.5 (Ωcm) ^-1 and resistivity ranged from 0.0044Ωcm to 0.013Ωcm. The samples obtained at low sintering temperature had more behavior and PTC thermistor samples taken at high temperature sintering behavior had more to NTC. (author)