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

Magnetic and Mossbauer measurements have been performed on polycrystalline substituted M-type hexagonal ferrites of compositions PbFe12-xScxO19 (x = 0, 0.5, 1, 1.5) and PbFe12-xInxO19 (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 Fe-57 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 degrees 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.