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Etude de la structure des verres des systèmes TeO2-MxOy (M = Ti, TI) par diffusion totale des rayons X et dynamique moléculaire

Abstract : This work aims to improve the structural description of the pure TeO2 glass and to give an insight of the structure of TeO2-MxOy binary glasses (M = Ti, Tl) by means of X-ray total scattering experiments and molecular dynamics (MD) simulations. We were able to determine, via Raman spectroscopy and X-ray total scattering experiments, that Tl2O causes the depolymerization of the glass structure whereas the addition of TiO2 leads to the conservation of Te(IV) environments. The MD simulations of the pure TeO2 glass and glasses within the TeO2-TiO2 system are carried out. First, we refined the Te(IV)-O interatomic potentials allowing us to reproduce TeO2 polymorphs as well as 14 crystalline structures containing TeO2. It was then demonstrated that the TeO2 glass consists largely of TeO4 and TeO3 units, giving a coordination number of 3.71, lower than that in the TeO2 polymorphs. Adding TiO2 tends to reinforce the connectivity within the tellurite framework via the reduction of the number of non-bridging oxygen atoms and the creation of Te-O-X bridges (with X = Te, Ti), which would justify the improvement of mechanical and thermal resistance of these glasses.
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Lyna Torzuoli. Etude de la structure des verres des systèmes TeO2-MxOy (M = Ti, TI) par diffusion totale des rayons X et dynamique moléculaire. Matériaux. Université de Limoges, 2020. Français. ⟨NNT : 2020LIMO0072⟩. ⟨tel-03151273⟩

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