title: An X-ray absorption spectroscopy investigation of the formation of FeCo alloy nanoparticles in Al2O3 xerogel and aerogel matrixes.
abstract: Extended X-ray absorption fine structure and X-ray absorption near-edge structure techniques were used to study in detail the structural characteristics of FeCo-Al2O3 nanocomposite xerogels and aerogels. The formation of bcc FeCo alloy, which cannot be assessed unambiguously by X-ray diffraction, dispersed within the alumina matrix was evidenced in the final samples obtained by heat treatment at 800 degrees C in reducing atmosphere. Aerogel samples reduced below 800 degrees C still present a fraction of oxidized metal together with the bcc alloy. The investigation of the xerogels and aerogels calcined at increasing temperature indicates that Fe(III) and Co(II) ions are present and they are located in the tetrahedral sites of the spinel structure of the matrix (gamma-Al2O3); moreover, the precursor of the spinel is more ordered in the aerogel sample than the xerogel sample.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Cagliari, Cittadella Universitaria di Monserrato, Strada Statale 554 bivio per Sestu, 09042 Monserrato, Cagliari, Italy. corrias@unica.it
authors.forename: Anna
authors.initials: A
authors.lastname: Corrias
authors.forename: Gabriele
authors.initials: G
authors.lastname: Navarra
authors.forename: Maria F
authors.initials: MF
authors.lastname: Casula
authors.forename: Sergio
authors.initials: S
authors.lastname: Marras
authors.forename: Gavin
authors.initials: G
authors.lastname: Mountjoy