Abstract
A low-temperature, ambient-pressure coprecipitation method for preparation of pure and modified barium ferrite particles BaFe3+12−2x Co2+xMxO19 is introduced; for this study, M=Ti4+ or Mo4+ and x=0.5, 0.9, 1.5, and 2.0. Hexagonal platelets, identified by SEM and TEM, varied in size (∼0.1 to 0.6 μm) and aspect ratio (∼2 to 7) with both heat treatment temperature and x value. Coercivity was controllable over a wide range from 500 to 1400 Oe. Line positions in x-ray powder diffraction spectra of pure and doped barium ferrite are in good agreement. The relative intensity of the (108) line to the (114) or the (107) line increases with Co/Mo doping, but does not change with Co/Ti doping. In the Co/Mo Mössbauer spectra, the relative intensities of the 12 K lines decrease monotonically from 50% (x=0) to ∼25% (x=2), suggesting a corresponding replacement of Fe3+ ions in the 12 K site. Both x-ray and Mössbauer measurements show a nonmagnetic phase in samples coprecipitated at 95 °C, not present in samples prepared at 55 °C. The saturation magnetization of doped particles was found to be independent of local crystalline order.
Published Version
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