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FILMS MINCES DE SNO2 (DIOXYDE D'ETAIN) DOPES AU PLATINE OU AU PALLADIUM ET UTILISES POUR LA DETECTION DES GAZ POLLUANTS : ANALYSES IN-SITU DES CORRELATIONS ENTRE LA REPONSE ELECTRIQUE ET LE COMPORTEMENT DES AGREGATS METALLIQUES

Abstract : We have analyzed the role played in the sensing processes, by Pt and Pd metallic aggregates dispersed in SnO2 thin films used for the detection of various reducing gases such as CO, H2S or NOx. X-ray Absorption Spectroscopy (XAS) analysis has allowed us to follow in situ the evolution of the oxidation state of platinum aggregates. When they are incorporated in a very weak quantity, platinum particles change in a reversible manner, their oxidation state, according to the nature of the atmosphere. The oxidation state of particles depend strongly on their size (0,5 - 4,5 nm): under CO the smallest ones change from fully oxidized to a reduced state where Pt -O bondings have been removed and replaced by Pt-C. From the analysis of the electrical conductance evolution under controlled atmosphere, it has been possible to correlate the electrical reply under CO with the platinum reduction rate. An electronic interaction metal-SnO2 is shown to be at the origin of the conductance peak observed at low temperature. A comparative study of the electrical replies between SnO2 thin films doped with Pt or Pd, in the presence of CO, H2 and H2S, has allowed us to propose a model describing the mechanisms of the detection process involved in each case.
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https://tel.archives-ouvertes.fr/tel-00010787
Contributor : Mounir Gaidi <>
Submitted on : Thursday, October 27, 2005 - 4:11:31 PM
Last modification on : Thursday, November 19, 2020 - 12:59:40 PM
Long-term archiving on: : Monday, September 20, 2010 - 1:07:37 PM

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  • HAL Id : tel-00010787, version 2

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Mounir Gaidi. FILMS MINCES DE SNO2 (DIOXYDE D'ETAIN) DOPES AU PLATINE OU AU PALLADIUM ET UTILISES POUR LA DETECTION DES GAZ POLLUANTS : ANALYSES IN-SITU DES CORRELATIONS ENTRE LA REPONSE ELECTRIQUE ET LE COMPORTEMENT DES AGREGATS METALLIQUES. Matériaux. Institut National Polytechnique de Grenoble - INPG, 1999. Français. ⟨tel-00010787v2⟩

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