Effect of anionic group [SiO4]4−/[PO4]3− on the luminescence properties of Dy3+-doped tungstate structural compounds

Novel scheelite structures of Li 2 Ca(WO 4 ) 2 , Li 2 Ca 2 (WO 4 )(SiO 4 ), and LiCa 2 (WO 4 )(PO 4 ) fluorescent materials were successfully prepared using a high-temperature solid-phase process. The compounds were characterized by X-ray diffraction and energy dispersive spectroscopy. The tests revealed that the substitution of [WO 4 ] 2− by [SiO 4 ] 4− or [PO 4 ] 3− tetrahedron in tungstate had no significant influence on the crystal structure of the Li 2 Ca(WO 4 ) 2 . When Dy 3+ ions were introduced as an activator at an optimum doping concentration of 0.08 mol%, all of the as-prepared phosphors generated yellow light emissions, and the emission peak was located close to 576 nm. Replacing [WO 4 ] 2− with [SiO 4 ] 4− or [PO 4 ] 3− tetrahedron significantly increased the luminescence of the Li 2 Ca(WO 4 ) 2 phosphors. Among them, the LiCa 2 (WO 4 )(PO 4 ):0.08Dy 3+ phosphor had the best luminescence properties, decay life ( τ = 0.049 ms), and thermal stability (87.8%). In addition, the as-prepared yellow Li 2 Ca(WO 4 ) 2 :0.08Dy 3+ , Li 2 Ca 2 (WO 4 )(SiO 4 ):0.08Dy 3+ , and LiCa 2 (WO 4 )(PO 4 ):0.08Dy 3+ phosphor can be used to fabricate white light emitting diode (LED) devices.