Formation of Cobalt Ferrites Investigated by Transmission and Emission Mossbauer Spectroscopy

This study focuses on cobalt and iron ordering within a ferrite structure CoxFe3-xO4, formed during a solid-state reaction of alpha-Fe2O3 and CoCl2. A unique combination of transmission and emission Mossbauer spectroscopy was employed to inspect selectively the positions of iron and cobalt atoms in the structure. The comparison of transmission and emission spectra allowed the determination of tetrahedral and octahedral positions occupation. The presented method of combining the two Mossbauer spectroscopy techniques is suitable for any compounds containing both iron and cobalt atoms. Additional information concerning the samples composition and morphology were obtained by X-ray powder diffraction and scanning electron microscopy. An increased level of Co atoms incorporation into the structure of ferrite was revealed when higher amounts of Co entered the reaction.