Abstract

In this work we investigate the magnetic properties of iron oxide nanoparticles obtained by two-step synthesis (seeded-growth route) with sizes that range from 6 to 18 nm. The initial seeds result monocrystalline and exhibit ferromagnetic behavior with low saturation field. The subsequent growth of a shell enhances the anisotropy inducing magnetic frustration, and, consequently, reducing its magnetization. This increase in anisotropy occurs suddenly at a certain size (similar to 10 nm). Electronic and structural analysis with X-ray absorption spectroscopy indicates a step reduction in the oxidation state as the particle reaches 10 nm size while keeping its overall structure in spite of the magnetic polydispersity. The formation of antiphase magnetic boundaries due to island percolation in the growing shells is hypothesized to be the mechanism responsible of the magnetic behavior, as a direct consequence of the two-step synthesis route of the nanoparticles.

Autore Pugliese

• Quarta Alessandra

Tutti gli autori

• Espinosa A.; Munoz-Noval A.; Garcia-Hernandez M.; Serrano A.; de la Morena J. J.; Figuerola A.; Quarta A.; Pellegrino T.; Wilhelm C.; Garcia M. A.

Titolo volume/Rivista

Journal of nanoparticle research

Anno di pubblicazione

2013

ISSN

1388-0764

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

Ultimo Aggiornamento Citazioni

Non Disponibile

Numero di citazioni Scopus

Non Disponibile

Ultimo Aggiornamento Citazioni

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Settori ERC

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Codici ASJC

Non Disponibile