Improvement of ageing issue in Zn0.4Fe2.1Co2Mn1.5O8 thermistor films.

The Zn-Fe-Mn-Co-O spinel-structured thermistor films were synthesized by chemical solution deposition methods. The ageing performance of these films was investigated by co-doping Fe and Zn into the films and annealing at different temperatures. The surface morphology and microstructure of these films were improved with the increasing temperature. The contents of Mn3+ and Mn4+ were stable with the annealing temperature due to iron and zinc co-doping. Annealing at 700 °C was necessary for the iron cation to be fully activated in the spinel lattice. The optimal electrical properties and ageing performance of the films were obtained at 800 °C, with an optimal B value of ˜4472 K and the lowest rate of change for the film resistance. [ABSTRACT FROM AUTHOR]