Morphological, structural and magnetic properties of α-Fe2O3 nanoparticles in an amorphous alumina matrix obtained by aqueous combustion method

We report on morphological, structural and magnetic properties of alpha-Fe2O3 nanoparticles in an amorphous alumina matrix synthesized by aqueous combustion method. The sample was characterized by X-ray powder diffraction (XRPD), high-resolution electron microscopy (HREM) and SQUID magnetometry. XRPD study reveals the phase purity of alpha-Fe2O3 whereas HREM images show an unusual spongy structure and well-crystallized nanoparticles with a size of about 25 nm. Magnetic measurements show a high irreversibility temperature T-irr approximate to 350 K, Morin transition at T-M approximate to 210 K, increase of the magnetization below T approximate to 45 K and hysteretic behavior below T-M at 5 K and 200 K. (C) 2009 Elsevier B.V. All rights reserved.