Zr-substituted SnO2-based NTC thermistors with wide application temperature range and high property stability

Abstract

Zr-substituted SnO2-based ceramics (Sn0.95−x Sb0.05Zr x O2, x ≤ 0.1) were prepared by using a wet-chemical synthesis method. The results show that the prepared ceramics have a pure tetragonal phase as that of SnO2 and have a typical characteristic of negative temperature coefficient (NTC) of resistivity over a wide temperature range from −50 to 300 °C. The room-temperature resistivity ρ 25 and material constant B 25/85 of the NTC thermistors increase from 4.77 Ω cm to 4.89 × 107 Ω cm and from 641 to 5085 K, respectively, when the content of Zr, x, changes from 0 to 0.1. The NTC thermistors also show high cyclic stability and ageing resistance. The analysis of impedance spectra reveals that the NTC effect mainly resulted from the grain-boundary contribution, and the conduction mechanisms of the Sn0.95−x Sb0.05Zr x O2 thermistors combine with the electron-hopping conduction and band conduction.