Sintering temperature and XPS analysis of Co2.77Mn1.71Fe1.10Zn0.42O8 NTC ceramics

Microstructure and electrical properties of Co2.77Mn1.71Fe1.10Zn0.42O8 (CMFZ) ceramics as a function of temperature were studied in the sintering process. The optimum sintering temperature of 1200 °C is determined to obtain the optimum microstructure and electrical properties. Both microstructure and electrical properties are sensitive to the different sintering temperatures. In particular, the appropriately increased sintering temperature enhances the densification and the homogeneity of grain size. However, the accelerated grain growth with a large number of closed pores appears when above the optimum sintering temperature. The electrical resistivity first increases and then decreases with the increased sintering temperatures. The ρ25 and B25/50 constant are in the range of 3072–4238 Ω cm and 4021–4056 K, respectively. X-ray photoelectron spectroscopy (XPS) was analyzed the evolution of resistivity clearly and proved the n-type semiconductor of CMFZ ceramics.