Role of Cr 3 ions on superexchange coupling in ?-Fe 2O 3 nanoparticles

Abstract

Synthesis of nanocomposites of iron oxide & chromium oxide (?-Fe 2O 3-Cr 2O 3) with different concentrations was carried out by a wet-chemical method and the structural, optical and hyperfine properties have been investigated. The prepared nanocomposites were characterized by powder X-ray diffractometry (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-VIS spectroscopy, Fourier transformed infrared (FTIR) spectroscopy and M�ssbauer spectroscopy. XRD measurements confirmed the formation of pure phase composites having particle sizes in nanometer regime. The same has been corroborated by TEM micrographs, which revealed that the formation of monodispersed nanocomposites have the average particle size 44 nm. M�ssbauer study of the samples showed the transition of iron oxide from anti-ferromagnetic state to paramagnetic state having a typical relaxation in the spectrum with increasing concentration of Cr 2O 3. � 2012 Elsevier B.V. All rights reserved.