Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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J.P.Laval, J.R.Duclère, V.Couderc, M.Allix, C.Genevois, V.Sarou-Kanian, F.Fayon, P.E.Coulon, S.Chenu, M.Colas, J.Cornette, P.Thomas, G.Delaizir*, 'Highly transparent fluorotellurite glass-ceramics: structural investigations and luminescence properties', Inorg. Chem. 58 16387 (2019) doi:10.1021/acs.inorgchem.9b01955

Crystallization from glass can lead to the stabilization of metastable crystalline phases, which offers an interesting way to unveil novel compounds and control the optical properties of resulting glass-ceramics. Here, we report on a crystallization study of the ZrF4-TeO2 glass system and show that under specific synthesis conditions, a previously unreported Te0.47Zr0.53OxFy zirconium oxyfluorotellurite anti-glass phase can be selectively crystallized at the nanometric scale within the 65TeO2-35ZrF4 amorphous matrix. This leads to highly transparent glass-ceramics in both the visible and near infrared ranges. Under longer heattreatment, the stable cubic ZrTe3O8 phase crystallizes in addition to the previous unreported anti-glass phase. The structure, microstructure and optical properties of 65TeO2-35ZrF4 Tm3+- doped glass-ceramics, were investigated in details by means of X-ray diffraction, scanning and transmission electron microscopies, 19F, 91Zr and 125Te NMR, Raman and photoluminescence spectroscopies. The crystal chemistry study of several single crystals samples by X-ray diffraction evidences that the novel phase, deriving from 3 type, corresponds in terms of longrange ordering inside this basic hexagonal/trigonal disordered phase (anti-glass), to a complex series of modulated micro-phases rather than a stoichiometric compound with various superstructures analogous to those observed in the UO3-U3O8 subsystem. These results highlight the peculiar disorder-order phenomenon occurring in tellurite materials.