Crystal growth, structures, and optical properties of the cubic double perovskites Ba2MgWO6 and Ba2ZnWO6

Single crystals of the tungstates Ba2MgWO6 and Ba2ZnWO6 have been grown for the first time. The crystals were prepared with molten potassium carbonate acting as a flux. According to the single-crystal X-ray diffraction structure determination, the compounds crystallize in space group Fm3¯m of the cubic system with a double perovskite structure, A2BB′O6. These structural findings were confirmed with neutron diffraction on polycrystalline samples synthesized by a high-temperature solid-state route. Both sets of diffraction data reveal that the M2+ and W6+ cations are fully ordered on the B and B′ sites. Ba2MgWO6 and Ba2ZnWO6 exhibit room-temperature luminescence with green and yellow emissions, respectively.