Molten salt synthesis, characterization, and luminescence properties of GdNbO4/LuTaO4:Eu3+ phosphors

GdNbO4:Eu3+ and LuTaO4:Eu3+ have been successfully prepared with different fluxes (NaCl, KCl, NaCl and KCl) by the molten salt method. X-ray diffraction (XRD) patterns illustrated that well crystallized GdNbO4:Eu3+ and LuTaO4:Eu3+ in the presence of fluxes were formed under reduced temperature (900 °C) in contrast to conventional method (GdNbO4:Eu3+: around 1200 °C; LuTaO4:Eu3+: around 1500 °C). Scanning electron microscope (SEM) images revealed that well dispersed particles were achieved (granular or rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that both niobate and tantalate are efficient hosts to sensitize europium red emissions. The results indicated that GdNbO4:Eu3+ using NaCl as the flux gave much enhanced red emission whereas LuTaO4:Eu3+ synthesized with the assistance of mixed salts (NaCl–KCl) achieved the best luminescence.