Effects of molybdenum concentration and valence state on the structural and magnetic properties of BaFe11.6MoxZn0.4−xO19 hexaferrites

Barium hexaferrites BaFe 11.6 Mo x Zn 0.4− x O 19 ( x = 0.1, 0.2, 0.4) were prepared by precipitation of the precursors using wet chemical mixture method and then sintering the dried powders at 1100 °C. The properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer, and Mössbauer spectroscopy. XRD patterns revealed that all prepared samples had BaFe 12 O 19 hexaferrite structure as a majority phase. SEM images demonstated that the samples consisted mainly of hexagonal platelet-like grains with diameters ranging from 100 to 500 nm. Mössbauer spectra revealed that Zn 2+ ions occupy 4 f 1 sites leading to the splitting of the 12 k component. However Mo 6+ ions occupy 2 b sites while Mo 4+ prefer 4 f 1 and 12 k sites. For the sample with x = 0.4,Mo 6+ and Mo 4+ ions were found to have preference for 2 b and 12 k sites, respectively, and to induce the development of Fe 2+ ions in the hexaferrite, leading to noticeable changes in the magnetic properties of the system. The observed magnetic properties were found to be consistent with the preferential site occupation of metal ions, and the hyperfine fields derived from Mössbauer spectra of these samples.