Effects of Molybdenum Concentration and Valence State on the Structural and Magnetic Properties of BaFe(11.6)Mo(x)Zn(0.4-x)O(19) 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 degree C. The properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer, and Mossbauer 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. Mossbauer spectra revealed that Zn(2+) ions occupy 4f(1) sites leading to the splitting of the 12k component. However Mo(6+) ions occupy 2b sites while Mo(4+) prefer 4f(1) and 12k sites. For the sample with x = 0.4, Mo(6+) and Mo(4+) ions were found to have preference for 26 and 12k 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 Mossbauer spectra of these samples.