Iron oxide nanopowders prepared by the electroexplosion of wire

Abstract

We have studied the effect of process parameters (supplied energy, oxygen concentration in the gas mixture, and others) on the particle size and yield of iron oxide nanopowder obtained by the electroexplosion of wire. Under optimal conditions, up to 25% of the particles in the powder were 15–20 nm in size (specific surface of up to 100 m2/g). Using several independent characterization techniques, we determined the phase composition, elemental composition, and structure of the material in the bulk and on the surface of the particles. The majority phase in the powder (90–98 wt %) is the metastable oxide γ-Fe2O3, which is sufficiently stable under ordinary storage conditions. The powder also contains the stable oxide α-Fe2O3. The effect of annealing in air and helium on the phase composition and carbon content of the powder is examined. The results are interpreted in terms of redox and diffusion processes.