Effect of Zn/Fe co-doping on the microstructure, electrical properties and aging behavior of Co–Mn–Ni–O NTC ceramics

Preparation of Zn/Fe co-doped Co–Mn–Ni–O negative temperature coefficient (NTC) ceramics by solid-phase method. The phase structure of the ceramics was analyzed by X-ray diffractometry. The results show that the increase in Zn/Fe content and the presence of a second phase (NiO) do not affect the stability of the cubic spinel structure. The optimum sintering temperature of 1175 ℃ was determined utilizing a DIL 402C dilatometer, and scanning electron microscopy showed that the ceramics had dense and homogeneous grains, the average grain size of the co-doped Zn/Fe ion specimens is smaller than that of the un-doped Zn/Fe ion specimens. The resistance test showed a B constant of 3237.974 K and a resistivity of 1972.384 Ω cm for the undoped Zn/Fe ions. The B constants for the samples co-doped with Zn/Fe ions ranged from 3044.719 to 3162.881 K and resistivities from 1760.821 to 2067.290 Ω cm. The resistivity of the specimens showed a linear relationship with the inverse of the temperature over the temperature range of − 50 to 100 ℃.