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Presence of Metallic Fe Nanoclusters in r-(Al,Fe)2O3 Solid Solutions

De Resende, Valdirene Gonzaga and Cordier, Anne and De Grave, Eddy and Laurent, Christophe and Eeckhout, Sigrid G. and Giuli, Gabriele and Peigney, Alain and Da Costa, Geraldo M. and Vandenberghe, Robert E. Presence of Metallic Fe Nanoclusters in r-(Al,Fe)2O3 Solid Solutions. (2008) Journal of Physical Chemistry C, vol. 112 (n° 42). pp. 16256-16263. ISSN 1932-7447

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Official URL: http://dx.doi.org/10.1021/jp8032098

Abstract

Powders of R-(Al1-xFex)2O3 solid solutions prepared by the calcination in air of the corresponding γ-(Al1- xFex)2O3 powders were studied by several techniques including X-ray diffraction, field-emission-gun scanning electron microscopy, transmission Mössbauer spectroscopy, integral low-energy electron Mössbauer spectroscopy (ILEEMS), and Fe K-edge X-ray absorption near-edge structure (XANES) measurements. The asymmetry of the characteristic Mo¨ssbauer doublet representing Fe3+ ions substituting for Al3+ ions in the corundum lattice of R-(Al1-xFex)2O3 solid solutions was resolved and explained for the first time by using two additional subspectra, i.e., a broad second doublet characteristic of a very distorted octahedral site for Fe3+ and a singlet attributable to R-Fe, suggesting the presence of metallic iron nanoclusters consisting of only a few number of atoms within the solid solution grains. ILEEMS studies showed that the Fe nanoclusters are evenly distributed among the surface layers and the cores of the grains. Fe K-edge XANES measurements further confirmed the occurrence of metallic iron. The proportion of Fe nanoclusters increases when the total iron content is decreased, as does the proportion of distorted octahedral site, suggesting that they are located around the iron nanoclusters. The formation of the metallic Fe nanoclusters in the R-(Al1-xFex)2O3 grains is thought to be a consequence of the γ f R phase transition which implies structural rearrangement on both the cationic and anionic sublattices.

Item Type:Article
Additional Information:Thanks to American Chemical Society editor. The definitive version is available at http://pubs.acs.org The original PDF of the article can be found at Journal of Physical Chemistry C website : http://pubs.acs.org/journal/jpccck
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > European Synchrotron Radiation Facility - ESRF (FRANCE)
Other partners > Universidade Federal de Ouro Preto – UFOP (BRAZIL)
Other partners > Ghent University (BELGIUM)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Celine Cabaup

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