Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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B.Diallo, M.Allix, E.Véron, V.Sarou-Kanian, I.Giboire, V.Montouillout, N.Pellerin, 'Deconvolution method of 29Si MAS NMR spectra applied to homogeneous and phase separated lanthanum aluminosilicate glasses', J. Non-Cryst. Solids 503–504 352-365 (2019) doi:10.1016/j.jnoncrysol.2018.10.026

The structural and microstructural properties of both homogeneous and phase separated lanthanum aluminosilicate (La2O3-Al2O3-SiO2 i.e. LaAS system) glasses were investigated. The microstructural observations and the structural characterization by X-ray Diffraction and by Nuclear Magnetic Resonance have highlighted the role of aluminum to favor a homogeneous vitreous aluminosilicate network by a high-level of Al/Si intermixing. A qualitative and simplified structure description is proposed from ²⁹Si nuclear magnetic resonance spectra assignment according to Qⁿ(mAl) species by controlling the deviation of chemical parameters. According to this approach, a homogeneous distribution of non-bridging oxygen in the aluminosilicate network and Al-O-Al linkages are considered for homogeneous glasses with high Al/Si atomic ratio. Phase separated samples are characterized by a low Al/Si atomic ratio inducing spinodal or nucleation/growth phase separation according to the depolymerization level. Homogeneity degree of the samples is discussed according to the intermixing level between silicon tetrahedra and aluminum polyhedra as a function of the proportion of Qⁿ and Qⁿ(mAl) species.