Synthesis of powellite-rich glasses for high level waste immobilization

Increasing 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.