Low-temperature magnetic properties of Fe3C/iron oxide nanocomposite

The magnetic properties of the Fe3C-based nanopowder synthesized by laser pyrolysis of ethylene and iron pentacarbonyl gases are investigated in the temperature range 4-293K by Mossbauer spectroscopy and magnetic measurements in DC and AC fields. Fe3C was identified as the dominant phase in the sample (75 wt%). The mean size of the Fe3C crystallites is estimated to be 20 nm. The residual phase in the sample is probably a mixture of nanocrystalline Fe3O4, gamma-Fe2O3, and alpha-Fe2O3. Zero-field-cooled and field-cooled DC measurements as well as real and imaginary parts of AC susceptibility curves are discussed. The nanopowder exhibits superferromagnetic behavior. (c) 2007 Elsevier B.V. All rights reserved.