Luminescence properties of NaY(WO4)2:Sm3+, Eu3+ phosphors prepared by molten salt method

Sm3+ singly doped NaY(WO4)2 and Sm3+, Eu3+ co-doped NaY(WO4)2 phosphors have been synthesized by molten salt method. The crystal structure and morphology were characterized by means of X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). In Sm3+ singly doped NaY(WO4)2 phosphors, the suitable doping concentration was proved. In Sm3+, Eu3+ co-doped NaY(WO4)2 phosphors, the energy transfer from Sm3+ to Eu3+ is confirmed by the luminescent spectra. A strong absorption line at 405 nm can be generated from 6H5/2-4K11/2 (4F7/2) transition of Sm3+ in Sm3+, Eu3+ co-doped NaY(WO4)2 phosphors, which is suitable for the emission of the near-ultraviolet light-emitting diodes. The energy transfer efficiency, energy transfer rate and average distance between Sm3+ and Eu3+ in the NaY(WO4)2:Sm3+, Eu3+ phosphors have been calculated based on the fluorescent dynamic analysis. Finally, the energy transfer mechanism between Sm3+ and Eu3+ is confirmed, the energy transfer occurs between 4G5/2 state of Sm3+ ions and 5D0 state rather than 5D1 state of Eu3+ ions.