Photoluminescence properties of LaSr2AlO5:Eu3+ phosphors for near UV-based w-LEDs

The combustion synthesis is used to prepare a series of LaSr2AlO5:Eu3+ phosphors. The morphology, photoluminescence properties and chromaticity are thoroughly investigated. The excitation peaks, which are located at 362 nm, 382 nm, 394 nm, and 417 nm, respectively, corresponding to the F-7(0) -> D-5(4), F-7(0) -> (5)G(3), F-7(0) -> L-5(6) and F-7(0) -> D-5(3) wavelengths. Upon 394 nm excitation, two emission peaks are observed at 591 nm (orange) and 613 nm (red), which correspond to the transitions D-5(0) -> F-7(1) and D-5(0) -> F-7(2) of Eu3+ ions, respectively. The emission spectra indicate red band of highest intensity from the electric dipole transition for D-5(0) -> F-7(2) at 613 nm. The Concentration quenching occurs at 0.5 mol % of Eu3+ ions. The results indicate that LaSr2AlO5:Eu3+ orange-red emitting phosphors under n-UV excitation can convert w-LEDs.