Luminescence behavior of Li2 Sr1-3x/2 Eux SiO4 red phosphors for LED applications.

Red-emitting Li(2)Sr(1-3x/2)Eux SiO4 0 ≤ x ≤ 0.5) phosphors were synthesized at 900 °C in air by a solid-state reaction. The synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the (5) L6 state of Eu(3+) ions is of significance for near ultraviolet pumped white light-emitting diodes and solid-state lighting. It is also noted that the position of the charge transfer state of Eu(3+) ions shifts towards the higher energy side (blue shift) by increasing the content of Eu(3+) ions. The predominant emissions of Eu(3+) ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the (5) D0 → (7)FJ (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red-emitting Li2 Sr(1-3x/2)Eux SiO4 phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light-emitting diode applications.