Zr-substituted SnO_2-based NTC thermistors with wide application temperature range and high property stability

摘要

Zr-substituted SnO_2-based ceramics (Sn_(0.95-x)Sb_(0.05)Zr_xO_2, 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 SnO_2 and have a typical characteristic of negative temperature coefficient (NTC) of resistivity over a wide temperature range from -50 to 300 ℃. 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 × 10~7 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 Sn_(0.95-x)Sb_(0.05)Zr_xO_2 thermistors combine with the electron-hopping conduction and band conduction.