Bismuth trioxide-tailored sintering temperature, microstructure and NTCR characteristics of Mn(1.1)Co(1.5)Fe(0.4)O(4) ceramics

Mn(1.1)Co(1.5)Fe(0.4)O(4) ceramics with tailored sintering temperature, microstructure, and NTCR characteristics were prepared using Bi(2)O(3) sintering additive by a solid-state reaction route. Densification and morphological characterization indicate that bismuth trioxide can play a critical role in the sintering process. The results reveal that the sintering temperature can be decreased significantly from 1200 °C to 1050 °C by using the appropriate content of Bi(2)O(3) additive. The resistivity decreases first and then increases with increasing Bi(2)O(3) content. The obtained B(25/50) value and ρ(25) ranges were 3647–3697 K, and 800–1075 Ω cm, respectively. Oxygen sorption theory can be used to illustrate the optimal thermal stability (ΔR/R(0) = 0.10%). Complex impedance analysis further elucidates that grain boundaries make a dominant contribution to the total resistance. The mechanisms of grain boundary conduction and relaxation behavior are systematically analyzed. These findings open up a window for the further advancement of NTC ceramics at lower sintering temperature.