Structural, magnetic, and Mossbauer spectroscopy of Cu substituted M type hexaferrites
Abstract BaFe 12 x Cu x O 19 hexaferrites were prepared using ball milling and sintering at 1100 degC. Refinement of the X ray diffraction patterns was carried out to determine the structural parameters and the ionic distribution over the crystallographic sites. The preferential site occupation and valence state of Cu was consistent with the results obtained from the analysis of Mossbauer spectra. Further, the magnetic parameters of the samples were discussed in light of the structural and Mossbauer analyses. The magnetic phase transition temperature was found to decrease with the level of Cu substitution, in accordance with the reduction of the superexchange interactions. Further, the magnetic softening of the hexaferrite and the significant reduction in magnetocrystalline anisotropy with Cu substitution was consistent with the ionic distribution in the lattice. This study clearly demonstrated the feasibility of using a simple method to fabricate hexaferrites with a modified coercivity, while maintain the saturation magnetization high enough for practical applications.