Sm/Al modified Sn0.94Sb0.06O2 ceramics for NTC thermistors

Abstract

Negative temperature coefficient (NTC) thermistors are key components for temperature sensors and actuators. In this work, Sn0.94-x-yAlxSmySb0.06O2+δ (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 (ρ25) 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.

Keywords

• sno2
• element doping
• thermistors
• ntc
• electrical property