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X-ray photoelectron spectroscopic study of non-stoichiometric nickel and nickel-copper spinel manganites

Drouet, Christophe and Laberty-Robert, Christel and Fierro, José Luis García and Alphonse, Pierre and Rousset, Abel X-ray photoelectron spectroscopic study of non-stoichiometric nickel and nickel-copper spinel manganites. (2000) International Journal of Inorganic Materials, 2 (5). 419-426. ISSN 1466-6049

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Official URL: http://dx.doi.org/10.1016/S1466-6049(00)00047-7

Abstract

The surface of non-stoichiometric nickel and nickel-copper spinel manganites has been investigated by X-ray Photoelectron Spectroscopy (XPS). The oxidation states of the nickel, copper and manganese cations present on the surface of the samples were determined from the analysis of the M 2p(3/2) core levels (M=Ni, Cu, Mn). In particular both Cu2+ and Cu+ were evidenced in the determined from the analysis of the M 2p(3/2) core levels (M=Ni, Cu, Mn). In particular, both Cu structure whereas only bivalent nickel was observed. The partial substitution of manganese by copper led to a chemical shift towards lower binding energy in the Ni 2p(3/2) region, which was explained by the displacement of some Ni2+ cations from tetrahedral to octahedral sites of the spinel structure. Finally, the surface atomic ratios Ni/Mn for nickel manganites, Ni/(Mn+Cu) and Cu/(Mn+Ni) for nickel-copper manganites, determined from XPS data, were compared to the ratios corresponding to the bulk composition. This study shows in all cases a nickel enrichment at the surface which is not affected by the copper content of the oxide. On the contrary, the ratio Cu/(Mn+Ni) was found to be lower than the corresponding bulk value.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com/science/article/pii/S1466604900000477
HAL Id:hal-00997764
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Consejo Superior de Investigaciones Científicas - CSIC (SPAIN)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Christophe DROUET
Deposited On:28 May 2014 15:17

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