Influence of Al3+/P5+ ions substitution on the structure and luminescence properties of Sr2SiO4:Eu2+ phosphors for white light emitting diodes

Sr2Si1-xAlxO4:Eu2+ and Sr2Si1-y,PyO4:Eu2+ with Al3+/P5+ ions partial substitution were prepared using a solid-state reaction method. The effects of Al3+/P5+ substitution on both structure and luminescence properties of Sr2SiO4:Eu2+ was investigated. A standard Sr2SiO4 structure was observed in the X-ray diffraction spectra of the Sr2Si1-xAlxO4:Eu2+ and Sr2Si1-yPyO4:Eu2+ samples. Some diffraction peaks, however, were changed after Al3+/ P5+ ions substitution due to the different ion radius. Upon excitation with 367 nm wavelength, all phosphor samples exhibit a broad emission band ranging from 420 nm to 680 nm, which is attributed to the 4f(6)5d(1)-> 4f(7) transition of the Eu2+ ions. The luminescence intensity of Sr2Si0.92Al0.08O4:Eu2+ and Sr2Si0.94P0.06O4:Eu2+ is 1.55 and 1.38 times higher, respectively, than that of Sr2SiO4:Eu2+. In addition, the luminescence lifetime of the Sr2SiO4:Eu2+ was also prolonged significantly by the introduction of Al3+ and P5+ ions. Overall, the results indicated that the application of Sr2SiO4:Eu2+ phosphors was effectively enhanced by Al3+/P5+ partial substitution in white light emitting diodes.