Mossbauer 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 Fe 3+ by Sc3+ and In3+ ions perturbs the axial magnetic order giving rise to a ngled magnetic structures. From the values of the quadrupole splitting of t he Fe-57 14.4 keV level, measured above and below the Curie temperatures, t he angle between the magnetic moment of the Fe3+ ions in various sublattice s and the hexagonal c-axis have been deduced. At 77 K the measured angles d o not exceed 20 degrees and depending on x are different for different subl attices. The dependence of x on the saturation magnetisation at 0 K, expres sed 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 angl es. (C) 2000 Kluwer Academic Publishers.