International audienceIn this study, we synthesized glass-ceramics from glasses in the system SiO2B2O3Na2OCaOAl2O3MoO3Gd2O3 by various heat treatments. Glass-ceramics contain only one crystalline phase in the bulk: powellite (CaMoO4). The influence of molybdenum and rare earth contents on powellite crystallization was studied using SEM and XRD. Heat treatments were optimized to lead to a wide range in size and concentration of powellite. Moreover, the molybdenum content left in residual glasses, calculated using XRD quantitation, showed that the residual glasses have a similar composition for a given Gd2O3 content after heat treatments. This work had led to the synthesis of two phase glass-ceramics with constant borosilicate glass matrices and powellite crystals with controlled sizes and concentrations

International audienceIncreasing amounts of MoO3 were added to SiO2-B2O3-Na2O-CaO-Al2O3 glasses in order to trap molybdenum as powellite (nominally CaMoO4). Different heat treatments were performed to study their influences on powellite crystallization by X-ray diffraction and EPR. The glass compositions studied in this work lead to glass-ceramics rich in CaMoO4, up to [MoO3] = 5 mol% no poorly durable Na2MoO4 phase was identified by XRD. Trivalent actinides surrogates (Gd3+) were observed to incorporate into CaMoO4 crystals