Effect of Cu and Fe addition on electrical properties of Ni–Mn–Co–O NTC thermistor compositions

The effect of addition of Cu and Fe on the electrical properties of Ni–Mn–Co–O based NTC thermistor compositions is studied. Compositions with very low resistivity were prepared by co-doping of very small amounts of Cu along with Co in NiMn2O4, without affecting the sensitivity very much. Compositions with high resistivity and good sensitivity were achieved by co-doping Fe with Co in NiMn2O4. The effect of sintering temperature on electrical properties was investigated and it was found that the resistivity and material constant increase with sintering temperature. The reliability characteristics of the compositions were studied by the accelerated thermal aging method. All the compositions exhibited very good reliability.