An investigation of trivalent substituted M-type hexagonal ferrite using X-ray and Mössbauer spectroscopy

Series of substituted M-type hexagonal ferrite has been synthesized, and studied by means of X-ray diffraction, IR and Mössbauer spectroscopy. The samples have the formula (BaCr _x Fe_12?x O₁₉) (with x = 0.0, 1.0, 2.0, 3.0, 4.0, and 5.0). X-ray diffraction studies prove that all samples has a single phase M-type hexagonal structure. The lattice parameters both a and c were found to be composition dependent. This observation was attributed to the atomic radii of the substituted cations. The Mössbauer spectra change from magnetically ordered (x = 0) toward magnetically ordered with strong line broadening. The broadening increases as the Cr content increase. Measurements at low temperature (80 K) restore the magnetic order. The Mössbauer parameters suggest that Cr³⁺ prefers to occupy the 4f₂ and 2a crystal sites. IR absorption bands were observed between 1,500 and 400 cm^?1, and confirm the structure in coincidence with X-ray results.