Structural and magnetic features of heterogeneously nucleated Fe-oxide nanoparticles

Iron oxide nanoparticles of diameter 14nm were synthesized by applying Pt seed-assisted heterogeneous thermal decomposition of Fe(CO) 5 in a two- stage procedure. The intense heating treatment resulted in a remarkable mean volume increment compared to previous studies. This method is able to control the nanoparticle mean diameter, keeping the demand for thermal energy at low levels. High-resolution electron microscopy images and the corresponding electron diffraction patterns revealed the appearance of a FePt3 core in each nanoparticle, surrounded by highly crystallized inverse spinel Fe3O4 formed after atmospheric oxidation, as shown by a combination of X-ray diffraction and chemical analysis. Magnetic measurements indicated that the presence of Pt-rich core does not cause any visible modi. cation to the values of saturation magnetization and anisotropy constant of nanoparticles, compared to homogeneously nucleated iron oxide particles of the same size. (c) 2008 Elsevier B. V. All rights reserved.