Combustion synthesis of rare earth activated and co-activated SrAl4O7 green long lasting phosphors

Abstract

Green emitting SrAl4O7:Eu2+, SrAl4O7:Eu2+, Dy3+, SrAl4O7:Eu2+, Dy3+, Ce3+ phosphors were synthesize by combustion method. The phosphor samples were well characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence(PL) emission and excitation spectra, Fourier transform infrared (FTIR) study, luminescence decay and afterglow decay. The excitation and emission spectra indicates that the phosphor could be well excited by UV light and give broad band emission due to the 4f65d→4f7 transition of Eu2+ ions. All the phosphors show green long lasting phosphorescence phenomena after the excitation source was removed. The SrAl4O7:Eu2+, Dy3+, Ce3+ phosphor has longest afterglow comparably than SrAl4O7:Eu2+ and SrAl4O7:Eu2+, Dy3+ phosphors. The SrAl4O7:Eu2+, Dy3+ phosphor exhibits one thermally stimulated luminescence (TSL) peak at 90°C and SrAl4O7:Eu2+, Dy3+, Ce3+ phosphor exhibits peak at 99°C. The luminescence decay curves are well fitted with double exponential equation. Scanning electron microscopy (SEM) study was carried out to investigate the surface morphology and the crystallite sizes.