Mössbauer and magnetic investigation of scandium and indium substituted PbFe12O19 hexagonal ferrite

Abstract

Magnetic and Mössbauer measurements have been performed on polycrystalline substituted M-type hexagonal ferrites of compositions PbFe_12−x Sc _x O₁₉ (x = 0, 0.5, 1, 1.5) and PbFe_12−x In _x O₁₉ (x = 0, 1, 2). The substitution of the Fe³⁺ by Sc³⁺ and In³⁺ ions perturbs the axial magnetic order giving rise to angled magnetic structures. From the values of the quadrupole splitting of the Fe⁵⁷ 14.4 keV level, measured above and below the Curie temperatures, the angle between the magnetic moment of the Fe³⁺ ions in various sublattices and the hexagonal c-axis have been deduced. At 77 K the measured angles do not exceed 20° and depending on x are different for different sublattices. The dependence of x on the saturation magnetisation at 0 K, expressed in Bohr magnetons, differs markedly in Sc and In containing compounds, partly due to the different substitution probability of iron in the spin up and spin down sublattices, and also due to the different spin canting angles.