Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging
Laguna-Marco, María Angeles (Instituto de Ciencia de Materiales de Aragón)
Piquer, Cristina (Instituto de Ciencia de Materiales de Aragón)
Gómez Roca, Alejandro. (Institut Català de Nanociència i Nanotecnologia)
Boada, Roberto (Instituto de Ciencia de Materiales de Aragón)
Andrés-Vergés, Manuel (Universidad de Extremadura. Departamento de Química Orgánica e Inorgánica)
Veintemillas-Verdaguer, Sabino (Instituto de Ciencia de Materiales de Madrid)
Serna, C. J. (Instituto de Ciencia de Materiales de Madrid)
Iadecola, A. (Elettra Sincrotrone Trieste)
Chaboy, J. (Instituto de Ciencia de Materiales de Aragón)

Data:	2014
Resum:	To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (FeO) phase for all the nanoparticles. The XAS spectra show that, in the samples synthesized by precipitation in aqueous media and laser pyrolysis, the Bi atoms neither enter into the iron oxide spinel lattice nor form any other mixed Bi-Fe oxides. No modification of the local structure around the Fe atoms induced by the Bi atoms is observed at the Fe K edge. In addition, contrary to expectations, our results indicate that the Bi atoms do not form a well-defined Bi oxide structure. The XAS study at the Bi L edge indicates that the environment around Bi atoms is highly disordered and only a first oxygen coordination shell is observed. Indefinite [BiO(OH)] units (isolated or aggregated forming tiny amorphous clusters) bonded through hydroxyl bridges to the nanoparticle, rather than a well defined BiO shell, surround the nanoparticle. On the other hand, the XAS study indicates that, in the samples synthesized by thermal decomposition, the Bi atoms are embedded in a longer range ordered structure showing the first and second neighbors.
Ajuts:	Ministerio de Ciencia e Innovación MAT2011-27573-C04-04 Ministerio de Ciencia e Innovación MAT2011-23641 Ministerio de Ciencia e Innovación MAT-2010-16022 Ministerio de Ciencia e Innovación MAT2010-09346-E
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Bismuth ; Computer simulation ; Contrast media ; Magnetic resonance imaging ; Magnetite nanoparticles ; Materials testing ; Models, chemical ; Models, molecular ; Molecular conformation ; Particle size
Publicat a:	Physical chemistry chemical physics, Vol. 16, issue 34 (Sep. 2014) , p. 18301-18310, ISSN 1463-9076

DOI: 10.1039/c4cp01392a
PMID: 25057849

Preprint 13 p, 973.0 KB

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