Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

► BaMoO4 and CaMoO4 formed by melt processing of carbonate and oxide precursors. ► Powellite phase exhibits radiation stability up to 1000 years. ► Normalized release rates for Ba, Ca, Mo (<0.05 g/m2). ► Photoluminescence and Raman measurements demonstrated monitoring of phase formation.