Controlled synthesis of single-crystal SrAl2O4:Eu2+,Dy3+ nanosheets with long-lasting phosphorescence

Single-crystal SrAl2O4:Eu2+,Dy3+ nanosheets were first synthesized by a reliable two-step method. More specifically, nanosheets bundles precursors were synthesized by a facile but efficient hydrothermal route in the absence of any organic additives, catalysts, and templates, and then SrAl2O4:Eu2+,Dy3+ nanosheets were obtained by thermally splitting the precursors. The products were characterized by multiple techniques including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that urea was very efficient to form nanosheets bundles precursors. The as-obtained SrAl2O4:Eu2+,Dy3+ nanosheets showed higher photoluminescence intensity (at 516 nm), compared with commercial corresponding powders. Furthermore, the SrAl2O4:Eu2+,Dy3+ nanosheets could sustain visible greenish-yellow light in dark places more than 16 h, suggesting potential applications in many fields.