Magnetic dilution of the iron sublattice in CoFe2−xScxO4 (0≤x≤1)

Substitution of Fe for Sc in CoFe2O4 spinel structure is presented. All CoFe2−xScxO4 compounds crystallize in the spinel type structure (space group Fd3̄m). By using X-ray diffraction studies, magnetic measurements and in-field 57Fe Mössbauer spectrometry, the limit of substitution has been determined to be equal to x=0.56. An increase in the cell parameter and the strains and a decrease in the apparent crystallites size are observed. For x>0.3, a partial oxidation of cobalt is evidenced and Co3+ is stabilized in the structure. A ferromagnetic behavior has been observed for all investigated compounds. As x increases, the Curie temperature and the hyperfine fields decrease. Following the Stephenson model, the diminution of TC is ascribed to a decrease of the main JAB interaction.