Mössbauer and magnetic studies of PbFe12-xCrxO19 hexagonal ferrites

Mössbauer and magnetic measurements have been performed on Cr substituted Pb-hexaferrite of composition PbFe12-xCrxO19 (0?x?6). The main hyperfine parameters for the Fe3+ nuclei of the various sublattices have been determined in the temperature range of 78-800 K. The data obtained give no evidence of deviation of the Fe3+ magnetic moments from the axial magnetic order. In addition, the Cr3+ ions do not occupy the hexahedral lattice sites. The rapid fall of the saturation magnetisation with increasing x cannot be simply explained with the replacement of the magnetic moment of the Fe3+ with that of Cr3+. The onset of a complex magnetic order induced by the presence of Cr3+ ions is involved.