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Vitroceramiques nano-structurées SiO2-SnO2 sous forme de monolithes et de guides d'ondes planaires élaborés par voie sol-gel : caractérisation structurale et activation par des ions de terres rares

Abstract : The obtention of efficient and compact light sources based on silica doped with rare earth (RE) ions demands high emission yields, which require a good dispersion of RE ions. Glass-ceramics, associating a glass with nanocrystals (NCs), allow such a dispersion and still assure adequate optical transparency. In addition, the NCs have broad absorption bands and can transfer their energy to the RE ions, thus improving the emission efficiency. In this work, silica-based ceramics containing SnO2 NCs were prepared as thin films and bulk by the sol-gel technique. The optical and structural properties of the thin films were compared with those of monoliths. Several parameters, such as the maximum concentration of tin, the temperature of crystallization and of densification, differ according to the morphology of the materials. The interaction between the silica matrix and SnO2 NCs was studied by combining several analytical techniques such as vibrational spectroscopies, XRD,TEM, porosimetry BET...The addition of tin retards the densification of the matrix, leaving a residual porosity. The luminescence of Er3+ and Eu3+ (emission bandwidths, lifetimes) clearly shows the existence of two types of host sites, one crystalline and the other amorphous. Finally, the SnO2 NCs promote the dispersion of the RE ions, leading to longer lifetimes and an energy transfer between crystal and RE.
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Submitted on : Monday, February 27, 2012 - 3:46:02 PM
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Thi Thanh Van Tran. Vitroceramiques nano-structurées SiO2-SnO2 sous forme de monolithes et de guides d'ondes planaires élaborés par voie sol-gel : caractérisation structurale et activation par des ions de terres rares. Chimie théorique et/ou physique. Université Lille1, Sciences et Technologies, 2011. Français. ⟨tel-00674563⟩

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