Structural refinement and magnetic tuning in cobalt-substituted SrFe12O19 hexaferrite

In this study, we synthesize strontium hexaferrite (SrFe12O19, SrM) with transition metal substitution cobalt (SrFe12-xCoxO19, SrCoM) with weight percentage (x = 3%, 5%, and 7%) through a chemical co-precipitation approach. The hexaferrite phase (P63/mmc) along with a small amount of secondary phase identified as hematite (α-Fe2O3) and halite (NaCl) were found from the x-ray diffraction analysis. A three-phase Rietveld refinement using FullProf software was used to evaluate the average bond lengths and angles, offering important information on superexchange interactions' impact inside the lattice. The magnetic ordering and crystal structure were also analyzed using neutron powder diffraction and the produced samples showed a ferrimagnetic arrangement at ambient temperature. The crystal structure, magnetic parameters, and maximal energy product (BH)max of the synthesized materials were found to be considerably affected by cobalt substitution: post-substitution, coercivity increases, while saturation magnetization and retentivity decrease. The present work emphasizes the potential of strontium hexaferrite and its cobalt-substituted derivatives as attractive magnetic materials for diverse magnetic applications.