Optimization and complexing agent-assisted synthesis of green SrAl2O4: Eu2+, Dy3+ phosphors through sol-gel process

A novel Eu2+-Dy3+co-doped strontium aluminate green long-lasting phosphors were synthesized via conventional sol-gel method with citric acid and polyethylene glycol used as chelating agent, respectively. Orthogonal experiments were employed to optimize the main synthesis conditions and obtain the optimum technological parameters. Subsequently, the crystal structure, morphology, decay curve and luminescence property of the composites were characterized. X-ray diffraction (XRD) showed that the samples were composed of single-phase SrAl2O4. Scanning electron microscopy (SEM) revealed that the resultant nanoparticles performed graininess with a size of 100 nm around. The excitation and emission spectra indicated that, excitation broadband chiefly lay in the ultraviolet range, and nanocrystalline particles emitted strong light at 510 nm, which corresponding to the typical characteristic 5d-4f transition of Eu2+ ion excited at around 360 nm. The long afterglow photoluminescence of nanoparticles SrAl2O4: Eu2+, Dy3+ (denoted as SAO: ED) was observed in the dark with the naked eye even after the removal of the excitation light. The luminescence properties suggested that SAO: ED phosphor may be regarded as a potential green phosphor candidate for near-UV and blue light-emitting diodes (LEDs).