Mössbauer study on the magnetic properties and cation distribution of CoFeO nanoparticles synthesized by hydrothermal method.

The structural, morphological, magnetic properties, and cation distribution of CoFeO nanoparticles were investigated by X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy, and vibrating sample magnetometer at room temperature. Single-phase CoFeO nanoparticles were synthesized by hydrothermal method. The results indicated that the average crystallite size and the magnetic hyperfine field of CoFeO nanoparticles increased with increasing reaction time, which suggested the improved crystallinity and magnetic order. The relative absorption area of component B in Mössbauer spectra assigned to the Fe ions occupying the octahedral B sites decreased with increasing reaction time, indicating that more Co ions migrated from the tetrahedral A sites to the B sites. The saturation magnetization of the samples increased with increasing reaction time, which resulted from the increase in crystallite size with longer reaction time. The increase of coercivity was attributed to both increasing crystallite size and more Co ions migrating to the B sites with increasing reaction time. [ABSTRACT FROM AUTHOR]