Synthesis and Characterization of Iron Oxide Nanoparticles Prepared by Electrical Explosion of Fe Wire in Ar–O₂ Gas Mixtures

Abstract

Iron oxide nanoparticles were prepared using a wire explosion method. Pure Fe wire was exploded in Ar–5%O₂, Ar–10%O₂ and Ar–30%O₂ gas mixtures. The variation in the oxygen partial pressure in the explosion chamber resulted in a full spectrum of iron oxide nanoparticles, the sizes of which ranged from 10 to 200 nm. The phases in the explosion products were augmented in the order FeO → magnetite (Fe₃O₄) → maghemite (γ-Fe₂O₃) → hematite (α-Fe₂O₃) as the oxygen partial pressure was increased. Among the oxide phases, magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃) were the major phases, and the identification and relative quantification of both phases was possible through a step-scan and peak deconvolution routine. The presence of the magnetite-maghemite phase mixture was also substantiated by a field-emission transmission electron microscopy (FE-TEM) study on individual particles. The average particle size and phase ratio (maghemite/magnetite) decreased with increasing oxygen partial pressure.