We report a detailed and morphological and structural characterization of iron/iron oxide core-shell nanoparticles with x-ray diffraction and x-ray absorption spectroscopy performed at both the Fe and O K edges. Core-shell nanoparticles with core size ranging from 7 to 21 nm were synthesized using the inert gas condensation technique followed by 12 h of controlled surface oxidation. Rietveld analysis of diffraction patterns shows the presence of α-Fe nanoparticles surrounded by a 2-3 nm-thick oxide layer with a disordered cubic spinel structure. Magnetite (Fe3O4) and maghemite (γ-Fe2O3), two different iron oxides, share this lattice structure, but x-ray diffraction was not able to distinguish between the two. An analysis of the Fe and O x-ray absorption spectra in both the near-edge and the extended energy regions is described. The analysis of the extended spectra was performed using the ab initio calculation of all significant contributions to the absorption cross section. We show that there are size-dependent changes in the local structure and oxidation state of the oxide shell, the relative fraction of maghemite increasing at the expense of magnetite as the core dimensions decrease. This size/structure correlation has been explained in terms of morphological and structural disorder arguments.

Size-dependent oxidation in iron oxide core-shell nanoparticles / L., Signorini; L., Pasquini; L., Savini; R., Carboni; F., Boscherini; E., Bonetti; A., Giglia; M., Pedio; N., Mahne; Nannarone, Stefano. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1538-4489. - STAMPA. - 68:(2003), pp. 195423-195423.

Size-dependent oxidation in iron oxide core-shell nanoparticles

NANNARONE, Stefano
2003

Abstract

We report a detailed and morphological and structural characterization of iron/iron oxide core-shell nanoparticles with x-ray diffraction and x-ray absorption spectroscopy performed at both the Fe and O K edges. Core-shell nanoparticles with core size ranging from 7 to 21 nm were synthesized using the inert gas condensation technique followed by 12 h of controlled surface oxidation. Rietveld analysis of diffraction patterns shows the presence of α-Fe nanoparticles surrounded by a 2-3 nm-thick oxide layer with a disordered cubic spinel structure. Magnetite (Fe3O4) and maghemite (γ-Fe2O3), two different iron oxides, share this lattice structure, but x-ray diffraction was not able to distinguish between the two. An analysis of the Fe and O x-ray absorption spectra in both the near-edge and the extended energy regions is described. The analysis of the extended spectra was performed using the ab initio calculation of all significant contributions to the absorption cross section. We show that there are size-dependent changes in the local structure and oxidation state of the oxide shell, the relative fraction of maghemite increasing at the expense of magnetite as the core dimensions decrease. This size/structure correlation has been explained in terms of morphological and structural disorder arguments.
68
195423
195423
Size-dependent oxidation in iron oxide core-shell nanoparticles / L., Signorini; L., Pasquini; L., Savini; R., Carboni; F., Boscherini; E., Bonetti; A., Giglia; M., Pedio; N., Mahne; Nannarone, Stefano. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1538-4489. - STAMPA. - 68:(2003), pp. 195423-195423.
L., Signorini; L., Pasquini; L., Savini; R., Carboni; F., Boscherini; E., Bonetti; A., Giglia; M., Pedio; N., Mahne; Nannarone, Stefano
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/456110
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 160
social impact