Magnetic properties of Cr/sup 3+/ substituted BaFe/sub 12/O/sub 19/ powders grown by a sol-gel method

Cr/sup 3+/ substituted Ba-hexaferrite was fabricated by a sol-gel method. The crystallographic and magnetic properties of BaFe/sub 12-x/Cr/sub x/O/sub 19/ (0/spl les/x/spl les/7) were investigated XRD, Rutherford backscattering spectrometry, vibrating sample magnetometry and Mossbauer spectroscopy. The crystal structure was found to be magnetoplumbite, typical of M-type hexagonal ferrite. By substituting Fe/sup 3+/ in BaFe/sub 12/O/sub 19/ by Cr/sup 3+/, we have been able to attribute the Mossbauer parameters to the 5 crystallographic sites of the structure. Only the octahedral sublattices were occupied by Cr ions. The isomer shifts indicate that the valence state of the Fe ions was Fe/sup 3+/. The Curie temperatures of BaFe/sub 12-x/Cr/sub x/O/sub 19/ decreased linearly increasing Cr-substitution, at a rate of 55 K/Cr atom.