Negative temperature coefficient (NTC) thermistors are key components for
temperature sensors and actuators. In this work, Sn0.94-x-yAlxSmySb0.06O2+?
(0 ? x ? 0.05, 0 ? y ? 0.15) ceramics were prepared by solid-state reaction
method for potential application of NTC thermistors. The Sm/Al co-doped SnO2
ceramics had the main phase with tetragonal structure as that of SnO2
crystal. The prepared ceramics presented adjustable room temperature
resistivity (?25) and temperature sensitivity (B value) for various Al
contents. Sm/Al co-doping significantly improved the ageing stability, the
resistance shift rate was below 3% after ageing at 150?C for 500 h, while
the average resistance shift rate was 41.4% of the ceramics without
Sm-doping. The conduction mechanisms and the effect of dopants on the ageing
stability were investigated by analysis of impedance spectra and element
valences combined with defect chemistry theory.