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Title: Probing the variability in oxidation states of magnetite nanoparticles by single-particle spectroscopy
Author: Fraile Rodríguez, Arantxa
Moya Álvarez, Carlos
Escoda-Torroella, M.
Romero, A.
Labarta, Amílcar
Batlle Gelabert, Xavier
Keywords: Òxid de ferro
Àcids grassos
Àcid oleic
Ferric oxide
Fatty acids
Oleic acid
Issue Date: 28-Jan-2018
Publisher: Royal Society of Chemistry
Abstract: We have studied the electronic and chemical properties of a variety of ensembles of size-and shape-selected Fe3O4 nanoparticles with single-particle sensitivity by means of synchrotron-based X-ray photoemission electron microscopy. The local X-ray absorption spectra reveal that the oxidation states and the amount and type of cations within the individual nanoparticles can show a striking local variability even when the average structural and magnetic parameters of the monodisperse ensembles appear to be compatible with those of conventional homogeneous magnetite nanoparticles. Our results show the key role played by oleic acid concentration in the reaction mixture on the formation and compositional homogeneity within individual nanoparticles. When the concentration of oleic acid is high enough, the nanoparticles are composed of a Fe3O4 core surrounded by a thin gamma-Fe2O3 shell. However, at a low concentration of the fatty acid, the Fe3O4 nanoparticles are likely inhomogeneous with small inclusions of FeO and Fe phases, as a result of an uncontrolled reduction of Fe3+ cations. All the foregoing underlines the importance of combining both advanced synthesis techniques and complementary single-particle investigations performed on a statistically significant number of particles so as to improve the understanding and control over electronic and magnetic phenomena at the nanoscale.
Note: Versió postprint del document publicat a:
It is part of: Journal of Materials Chemistry C, 2018, vol. 6, num. 4, p. 875-882
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ISSN: 2050-7526
Appears in Collections:Articles publicats en revistes (Física de la Matèria Condensada)

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