Structural and magnetic studies of Fe2O3/SiO2 granular nanocomposites

G. POZO LÓPEZ, S.P. SILVETTI, A.F. CABRERA AND A.M. CONDÓ

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Año: 2009 vol. 404 p. 2777 - 2779

0921-4526

Fe2O3/SiO2 nanocomposites were synthesized by mechanical alloying,using Fe and SiO2 powders as precursors. After 340h milling, the sample essentially consists of hematite and amorphous silica. TEM images show hematite particles embedded in and surrounded by an amorphous silica matrix.Abroad size distribution—5–50nm—of hematite particles is found, and other Group of very small—2–3 nm—unidentified particles are observed. Room temperature Mossbauer spectra show a paramagnetic doublet, which may correspond to a non-crystalline phase in the sample (probably the small unidentified particles),and a sextet corresponding to hematite. Magnetic properties were investigated by measuring hysteresis curves at different temperaturas (5–300K) and by zero-field-cooled(ZFC)and field-cooled (FC) magnetization curves (10mT). The hysteresis loops were well fitted by a ferromagnetic contribution. No evidence of Morin transition is found down to 5K.