White-light emission from Li2Sr1-3x/2Dy x SiO4 phosphors

Li2Sr1-3x/2Dy (x) SiO4 phosphors were synthesized at 900A degrees C in the normal atmosphere by a solid-state method. The synthesized phosphors were characterized by X-ray powder diffraction (XRD) and photoluminescence (PL) spectra. The photoluminescence excitation (PLE) spectra show excitation peaks ranging from 300 to 400 nm due to the 4f-4f transitions of Dy3+. This mercury-free excitation is useful for solid-state lighting and light-emitting diodes (LEDs). The predominant emission of Dy3+ ions under 349 nm excitation is observed at 479 nm (blue) due to the F-4(9/2)-> H-6(15/2) transitions and 572 nm (yellow) due to F-4(9/2)-> H-6(13/2) transitions, respectively. The PL results reveal that the optimal concentration of the Dy3+ ions in Li2Sr1-3x/2Dy (x) SiO4 phosphors is x=0.03 mol. The nature of the resonance energy transfer for the Dy3+ ions is confirmed by Huang's rule. Simulation of the white light excited by 349 nm near-ultraviolet (n-UV) light is also performed for its potential for white LEDs.