Photo- and mechano-luminescent properties of color-tunable (Eu2+, Dy3+)-co-doped strontium/calcium aluminate phosphor

Abstract

(Eu2+, Dy3+)-co-doped strontium/calcium aluminate phosphor as one of color-tunable emission materials was synthesized via solid-state reactions at 1300 °C for 3 h. Effect of strontium/calcium ratio on the crystal structure, particle size/morphology as well as photo- and mechano-luminescent properties of the phosphors was investigated by X-ray diffraction, Rietveld method, scanning electron microscopy with energy dispersive X-ray spectroscopy, and spectrophotometry. The mechano-luminescent properties were measured by two mechanical stress instruments (i.e., impact and compression), respectively. The results reveal that a mixed phase with SrAl2O4 and CaAl2O4 has a monoclinic structure with a space group P21 for SrxCa1-xAl2O4: 0.001Eu2+, 0.001Dy3+ phosphor (x = 0.2–0.8), resulting in the change of crystallographic parameters due to different calcium/strontium ratios. According to the results of photo- and mechano-luminescent characterizations, SrAl2O4: 0.001Eu2+, 0.001Dy3+ phosphor (x = 1.0) has a superior mechano-luminescent property rather than CaAl2O4: 0.001Eu2+, 0.001Dy3+ phosphor (x = 0), although they both have photo-luminescent properties. Furthermore, the CEI diagram indicates that the emission color of the phosphor can be tuned from blue to bluish white and eventually to green, and the mechano-luminescent peak appears and becomes intense as Sr2+ ions substitute for Ca2+ ions in the phosphor gradually. In addition, the photo- and mechano-luminescent mechanisms of phosphor were also discussed.