Exfoliation of hematite: Morphological, structural and magnetic investigations

Three natural specimens of hematite are characterized using X-ray diffraction, magnetometry, IR/Raman and Mössbauer spectroscopy, with focus on the Morin transition. All exfoliated by grinding prolonged sonication in dimethylformamide, followed centrifuging to extract debris from supernatant. This material is electron microscopy atomic force microscopy. There three main Fe2O3 constituents: lamellae that hundreds nanometers diameter typically 1–10 nm thick, nanoparticles about 100 size ultra-fine smaller than 10 nm. Estimated yield 10−3−10−4 volume. iron antiferromagnetically ordered at room temperature, including 30% superparamagnetic contributes a quadrupole doublet spectrum, but characteristic weak net moment due spin canting absent. Unlike normal nanoparticles, there no transition range 300 K. The absence understandable because cleave planes make small angles c-axis.