Indexed on: 24 Sep '15Published on: 24 Sep '15Published in: Bulletin of the Russian Academy of Sciences: Physics
The phase composition and structure of iron oxide nanopowders obtained by different chemical means are explored via X-ray diffraction, transmission electron microscopy, and Mössbauer and X-ray photoelectron spectroscopy. It is shown that nanoparticles with sizes of 10–85 nm are nonstoichiometric magnetite–maggemite compounds. Particles with average sizes of ~10 nm are close in composition and structure to (γ-Fe2O3) maggemite, while those with sizes above 70 nm resemble (Fe3O4) magnetite. Estimates of the magnetite particle size yield a value of 130 nm, which may be considered the conditional boundary from the bulk state to nanoscale effects.