Properties of nanocomposites of α-Fe and Fe3O4

Brahma, P. ; Banerjee, S. ; Das, D. ; Mukhopadhyay, P. K. ; Chatterjee, S. ; Nigam, A. K. ; Chakravorty, D. (2002) Properties of nanocomposites of α-Fe and Fe3O4 Journal of Magnetism and Magnetic Materials, 246 (1-2). pp. 162-168. ISSN 0304-8853

Full text not available from this repository.

Official URL:

Related URL:


Composites of α-Fe and Fe3O4 having dimensions in the range 10-20 nm have been prepared by subjecting micrometer-sized α-Fe2O3 powders to a reduction treatment in hydrogen at a temperature 683 K for a duration from 5 to 40 min. The specimens have been characterized by Mossbauer spectroscopy. The latter shows the presence of a substantial amount of superparamagnetic particles. The fraction of these particles increases as the reduction treatment is enhanced. The incorporation of hydrogen atoms during the reduction process appears to break down the precursor oxide particles. Magnetic susceptibility shows a maximum at around 125 K which arises due to Verwey transition in Fe3O4 particles. Magnetization measurements on zero-field cooled and field cooled specimens indicate a blocking temperature close to 300 K. Coercivity variation with temperature shows an unusual behaviour. Exchange coupling between the ferro- and ferri-magnetic particles seems to be the reason behind this. The presence of such nearest neighbouring pairs of α-Fe/Fe3O4 is confirmed by the DC resistivity data which show electron tunnelling between metal islands separated by Fe3O4 granules.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Nanocomposites; α-fe; Mossbauer Spectroscopy; Superparamagnetic Particles
ID Code:7411
Deposited On:25 Oct 2010 11:39
Last Modified:28 May 2011 04:39

Repository Staff Only: item control page