Abstract
The use of γ Fe2O3 as a magnetic recording pigment is well known. Most commonly it is prepared by dehydration of the ∝ FeOOH to ∝ Fe2O3, reduction of ∝ Fe2O3 in hydrogen or other reducing gas to Fe3O4 and finally oxidation of the Fe3O4 to γ Fe2O3.Because of the known influence of grain boundaries on magnetic domains, a knowledge of the microstructure of the individual magnetic particles is important in theoretical considerations of switching mechanisms. Literature references disagree on the microstructure of γ Fe2O3. Some investigators claim the individual particles are essentially single crystalline ; others claim the particles are polycrystalline. In the present work, we have found no evidence that sub-grains are nucleated during the structural transformations of ∝ Fe2O3 to γ Fe2O3. Rather we have found that the single crystalline character of the starting ∝ FeOOH is preserved through the conversion to γ Fe2O3.
Published Version
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