Low temperature synthesis and characterization of gamma -Fe₂O₃ particles

The liquid mix technique has been used to synthetize in a direct way gamma -F₂O₃ 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 -Fe₂O₃ phase is stabilized, but when only Fe ions are included in the solution the final phases are alpha -Fe₂O₂ and Fe₂O₄. 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 -Fe₂O₃ phase. Hysteresis loop measurements show a small coercive field characteristic of nonacicular gamma -Fe₂O₃ particles.