Europium-Doped Sol-Gel SiO2-Based Glasses: Effect of the Europium Source and Content, Magnesium Addition and Thermal Treatment on Their Photoluminescence Properties

International audienc

The Effect of Size and Thermal Treatment on the Photoluminescent Properties of Europium-Doped SiO2 Nanoparticles Prepared in One Pot by Sol-Gel

International audienceEuropium (Eu)-doped silica nanoparticles have attracted great interest for different applications, in particular in biomedicine as biosensors or for tissue regeneration. Sol-gel is the most common process used to prepare those particles, with size varying from tens to hundreds of nanometers. In this article, we focus our attention on the comparison between two commonly used sol-gel derived methods: reverse microemulsion (for particles smaller than 100 nm) and Stöber method (for particles larger than 100 nm). Europium concentration was varied between 0.2 and 1 mol%, and the nanoparticle diameters were 10, 50 and 100 nm. The link between the local environment of europium ions and their optical properties was investigated and discussed. Using Transmission Electron Microscopy, nitrogen sorption, X-ray diffraction, Fourier-Transform Infra-Red and pulsed doubled Nd:YAG laser, we confirmed that fluorescence lifetime was improved by thermal treatment at 900 °C due to the elimination of aqueous environment and modification of structure disorder. The size of nanoparticles, the amount of europium and the thermal treatment of obtained materials influence the emission spectra and the decay curves of Eu3+

Size and temperature effect on the photoluminescent properties of Europium-doped silica nanoparticles

International audienc

Well defined rare-earth doped silica nanoparticles for a new opportunity in photoluminescent uses : Synthesis and characterization

International audienc

Size and temperature effect on the photoluminescent properties of europium-doped silica nanoparticles

International audienc

Size and temperature effect on the photoluminescent properties of Europium-doped silica nanoparticles

International audienc

Size and temperature effect on the photoluminescent properties of europium-doped silica nanoparticles

International audienc

Size and temperature effect on the photoluminescent properties of Europium-doped silica nanoparticles

International audienc

RARE-EARTH DOPED MG-SILICATE NANOPARTICLES IN SILICA FIBER: MOLECULAR DYNAMICS SIMULATIONS FROM THE PREFORM TO THE FIBER

International audienceAn enhancement of the spectroscopic performance of rare-earth-doped silica optical fibers is still required for new photonics applications. An interesting route to tailor their optical behavior consists in embedding rare-earth ions within dielectric nanoparticles in the core of optical fibers. Experimentally, such nanoparticles can be produced in situ through spontaneous phase separation phenomenon within a MgO-SiO2 binary melt, during melt/quench sequences of MCVD fabrication process of the preform 1,2. Then, fibers are obtained by drawing at high temperature a preform containing nanoparticles. First report on the drawing process reveals an elongation of the nanoparticles in the drawing direction as well as a breakup of the larger ones 3. In this Molecular dynamics study, we use a new simple transferable model 4 to show that phase separation occurring in the MgO-SiO2 binary melt leads to the separation of liquid phases with mixed composition: Si-rich Mg-poor phases on one hand, Mg-rich Si-poor phases on the other hand. These latter phases, the so-called nanoparticles, are amorphous, non-spherical and exhibit a wide range of sizes. Mg-O coordination and MgO content increase with the nanoparticle size. With rare-earth doping, the larger nanoparticles are over-concentrated in luminescent ions. We show that the rare-earth clustering effect is prevented, compared with a pure silica matrix. Finally, at high temperature, we apply a uniaxial elongation to the nanostructured preform to mimic the experimental drawing step leading to the fiber. We report here on the effects of this drawing process on the nanoparticles characteristics

Molecular dynamics study of rare earth-doped Mg-silicate nanoparticles in vitreous silica: from the preform to the fiber

International audienceA Molecular Dynamics study of rare-earth doped Mg-silicate nanoparticles in vitreous silica: from the preform to the fiber. New lasers and amplifiers still require an enhancement of the spectroscopic performance of rare-earth-doped silica optical fibers. In order to tailor their optical behavior, a route of interest consists in embedding rare-earth ions within dielectric nanoparticles in the core of optical fibers. Nanoparticles are formed through spontaneous phase separation phenomenon within a MgO–SiO2 binary melt, during melt/quench sequences of MCVD fabrication process of the preform [1][2]. Then, fibers are obtained by drawing at high temperature a preform containing nanoparticles. First report on the drawing process reveals an elongation of the nanoparticles in the drawing direction as well as a breakup of the larger ones [3]. In this Molecular dynamics study, we use a new simple transferable model [4] to show that phase separation occurring in the MgO–SiO2 binary melt, leads to separation of liquid phases with mixed composition: Si-rich Mg-poor phases on one hand, Mg-rich Si-poor phases on the other hand. These latter phases, the so-called nanoparticles, are amorphous, non spherical and exhibit a wide range of sizes. Mg-O coordination and MgO content increase with the nanoparticle size. With rare-earth doping, the larger nanoparticles are over-concentrated in luminescent ions. Due to an oxygen-rich environment in the nanoparticles, we show that the rare-earth clustering effect is greatly prevented, compared with a pure silica matrix. Finally, at high temperature, we apply a uniaxial elongation to the nanostructured preform to mimic the experimental drawing step leading to the fiber. We report here results on the effects of this drawing process on the nanoparticles characteristics