The effect of Sm 3+ co-doping on the luminescence properties of Ca 2 · 85 Li 0 · 15 (PO 4 ) 1 · 85 (SO 4 ) 0.15 : Dy 3+ white-emitting phosphors

Abstract(#br)A novel white emitting phosphate-based phosphor Ca 3- x Li x (PO 4 ) 2- x (SO 4 ) x :Dy 3+ , Sm 3+ with high emission intensity and lower correlated color temperature were successfully synthesized via the sol-gel method.(#br)The structures of these prepared phosphors matched well with standard Ca 3 (PO 4 ) 2 . The Dy 3+ -doped Ca 3- x Li x (PO 4 ) 2- x (SO 4 ) x phosphors showed white luminescence via the combination of blue (487 nm) and yellow (578 nm) emissions, which were attributed to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 electron transitions of Dy 3+ , respectively. The synthesized phosphor exhibited a significant enhancement in luminescence intensity at the optimum value of x = 0.15. With the incorporation of Sm 3+ , a warm white emission with lower correlated color temperature (4281 K) was achieved in Dy 3+ /Sm 3+ co-doped samples. The obtained external quantum efficiency reached 21.7% in the optimized phosphor. The improved performance was strongly associated with red emission supplemented by Sm 3+ , and it demonstrated the existence of efficient energy transfer between the Dy 3+ and Sm 3+ ions ( 4 F 9/2 → 4 G 7/2 and 4 F 9/2 → 4 G 5/2 ). Overall, the investigation carried out by us has revealed that the luminescence properties of Ca 3 (PO 4 ) 2 phosphor can be significantly improved through Li + /S 6+ partial substitution and Dy 3+ /Sm 3+ co-doping