Electrical properties of Ga/V-modified ZnO ceramic thermistors

The Zn1−xGaxO (x = 0–0.020) ceramics modified with V2O5 were prepared by solid-state reaction method. The phase composition, microstructure, electrical conductivity, temperature sensitivity, and thermal aging property were investigated. The main phase of prepared ceramics is a hexagonal wurtzite crystal structure with a space group of P63mc (186). Ga2O3 phase was detected in ceramics when the content of Ga-ion x is higher than 0.010. V2O5 acts as sintering aids and electrical stabilizer and enhanced the ceramic sintering ability. The Ga/V-modified ZnO ceramics exhibit typical NTC characteristics and have high temperature sensitivity with material constant of B values ranging from 3659 to 4590 K. The electrical properties and aging characteristics were studied with alternating current impedance spectrum and X-ray photoelectron spectroscopy. The Ga/V-co-modified ZnO ceramics show high electrical stability with resistance change rate (ΔR/R0) less than 1.85% after aged at 150 °C for 1000 h. The increase of resistance by aging mainly came from the grain boundary effect.