Stabilization Of FeCo Alloy Phase In FeCo-SiO2 nanocomposites

¹Nanostech Laboratory, Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India

²Institute of Physics, University of São Paulo, São Paulo 05508-090, Brazil

³Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India

⁴Sincrotrone Trieste S.C.p.A. di interesse nazionale, Trieste, Italy

Adv. Mater. Lett., 2013, Ion Beam Special Issue, 4 (6), pp 390-397

DOI: 10.5185/amlett.2012.ib.101

Publication Date (Web): Mar 16, 2013

Copyright © IAAM-VBRI Press

E-mail: ghoshsantanu1@yahoo.co.in

Abstract

A series of FeCo-SiO₂ granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H₂) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe⁰, Co⁰) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H₂ environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O₄ and CoFe₂O₄ phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H₂ environment annealing (450-700 ^oC) leads to formation of bcc FeCo alloy. 

Keywords

Nanocomposite, fast atom beam sputtering technique, XANES analysis, XRD and Raman analysis.