Luminescent properties of the white long afterglow phosphors: Sr3Al2O5Cl2: Eu2+, Dy3+

A series of white long afterglow phosphors, Sr3Al2O5Cl2: Eu2+, Dy3+, have been successfully synthesized by the solid state reaction. Their structure, morphology, luminescent properties and long afterglow properties were investigated by X-ray diffraction, scanning electron microscopy, luminescence spectra, the luminescence decay curve and thermoluminescence spectrum. The phosphor Sr2.82Al2O5: 0.04Eu2+, 0.14Dy3+ under 340 nm light excitation exhibits two wide emission bands, which are located at ~445 and ~590 nm, respectively. Bright white light can be observed from this phosphor with appropriate CIE values (x = 0.313, y = 0.263). The white afterglow duration of Sr2.82Al2O5Cl2: 0.04Eu2+, 0.14Dy3 + is about 1.5 h (>0.35 mcd/m2). The possible generation of the afterglow has been discussed.