Effect of replacement of Ca by Ln (Ln=Y, Gd) on the structural and luminescence properties of CaWO4:Eu3+ red phosphors prepared via co-precipitation

Abstract Eu 3+ -doped calcium based tungstate, Ca 1− x Ln x WO 4 :Eu 3+ (Ln = Y, Gd) red-emitting phosphors were prepared by co-precipitation method with NH 4 HCO 3 –NH 3 ·H 2 O system as the precipitating aid agent. X-ray diffraction results reveal that the synthesized Ca 1− x Ln x WO 4 :Eu 3+ have scheelite structure with pure phase. Infrared spectra show strong absorption peaks between 803 and 440 cm −1 which are assigned to the vibration of O–W in WO 4 2− tetrahedron. The Energy Disperse Spectroscopy analysis reveals that the red phosphors have been successfully prepared by co-precipitation method according to theoretic ratio. Due to the 5 D 0 – 7 F 1–3 transitions of Eu 3+ ions, photoluminescence spectra show a red emission at about 614 nm under excitation of 395 nm (commercial ultraviolet) and 465 nm (blue chip). With Ln lanthanide added in host, the luminescent intensity of Ca 1− x Ln x WO 4 :Eu 3+ ( x = 0.4, 0.5) is obviously improved comparing with that of CaWO 4 :Eu 3+ by several times.