Copper and iron based thin film nanocomposites prepared by radio frequency sputtering. Part I: elaboration and character
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Copper and iron based thin film nanocomposites prepared by radio frequency sputtering. Part I: elaboration and characterization of metal/oxide thin film nanocomposites using controlled in situ reduction process A. Barnabe´ • A. Chapelle • L. Presmanes P. Tailhades
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Received: 3 October 2012 / Accepted: 24 December 2012 / Published online: 8 January 2013 Ó Springer Science+Business Media New York 2013
Abstract Copper and iron based thin films were prepared on glass substrate by radio-frequency sputtering technique from a delafossite CuFeO2 target. After deposition, the structure and microstructure of the films were examined using grazing incidence X-ray diffraction, Raman spectroscopy, electron probe micro-analysis and transmission electron microscopy coupled with EDS mapping. Target to substrate distance and sputtering gas pressure were varied to obtain films having different amount and distribution of copper nanoparticles and different composition of oxide matrix. The overall reaction process, which starts from CuFeO2 target and ends with the formation of films having different proportion of copper, copper oxide and iron oxide, was described by a combination of balanced chemical reactions. A direct relationship between the composition of the metal/oxide nanocomposite thin film and the sputtering parameters was established. This empirical relationship can further be used to control the composition of the metal/oxide nanocomposite thin films, i.e. the in situ reduction of copper ions in the target.
Introduction Nanocomposites have been widely prepared and investigated due to their special properties which help in producing special engineering materials. In particular, nanometric metallic particles dispersed in an oxide matrix show special or improved physico-chemical properties [1–5].
A. Barnabe´ (&) A. Chapelle L. Presmanes P. Tailhades Institut Carnot CIRIMAT—UMR CNRS 5085, Universite´ Paul Sabatier Toulouse III, 118 Route de Narbonne, 31062 Toulouse Cedex 4, France e-mail: [email protected]
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Nanocomposites composed of noble metals and metal oxides matrix are being considered as prospective materials for applications in catalysis, electronics, fuel cells and gas sensors [6–11]. It is known that instability of the size of noble metal clusters is one of the main reasons for the observed changes in reactivity of modified metal oxide surface. The fabrication processes and the phase stability of these metal and metal oxides were particularly studied [5, 12–14]. With thin films of these materials, there are different additional technological applications as in coated medical devices [15], magnetic recording media [16], electro-optical systems [17–19], photo-catalytic coatings [20, 21] or gas-sensing apparatus [10]. For the latter, it has been proven that the dispersion of small noble metal particles in an oxide matrix enhance or create optical sensitivity to different gases [22, 23]. Moreover, in the form of thin films, these materials allow mass production of devices at low cost with high control
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