Low temperature synthesis and characterization of gamma -Fe/sub 2/O/sub 3/ particles

The liquid mix technique has been used to synthetize in a direct way gamma -F/sub 2/O/sub 3/ small particles at 150 degrees C. The refinement of X-ray diffraction patterns by the Rietveld method shows that when the initial citrate solution contains Ba and Fe ions, the spinel gamma -Fe/sub 2/O/sub 3/ phase is stabilized, but when only Fe ions are included in the solution the final phases are alpha -Fe/sub 2/O/sub 2/ and Fe/sub 2/O/sub 4/. X-ray diffraction line broadening and TEM have been used to determine the crystallites' size and the morphology. It is argued that the presence of Ga ions leads to a slower dehydration of the resin, thus allowing to stabilize the gamma -Fe/sub 2/O/sub 3/ phase. Hysteresis loop measurements show a small coercive field characteristic of nonacicular gamma -Fe/sub 2/O/sub 3/ particles.<
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