The important base of its application performance can be constituted by combining microstructure with electrical conductivity of spinel nickel ferrite ceramics. In this study, nickel ferrite ceramic powders were prepared by a high temperature solid-phase reaction and ceramic blocks were prepared by molding and sintering technology. X-ray diffraction, scanning electron microscopy, conductivity measurement and X-ray photoelectron spectrometry were employed for analyzing the phase composition, microstructure, electrical conductivity, and valence states of Fe ions. The grain growth mode and conduction mechanism of nickel ferrite ceramics were also discussed. Hexagonal growth spirals and growth hillocks were observed on each crystal plane of nickel ferrite single crystals. The growth of nickel ferrite crystals takes place by a spiral dislocation growth mechanism, indicating that the more Fe²⁺ ion formed in the sites of octahedral B of NiFe₂O₄ ceramics, the better the electrical conductivity of this ceramic materials

Keywords: Ceramics, Nickel ferrite, Grain growth, Conduction mechanism