Size-Dependent Optical Properties of Nanoscale and Bulk Long Persistent Phosphor SrAl2O4:Eu2+, Dy3+

摘要

Nanoscale long persistent phosphor SrAl2O4:Eu2+, Dy3+was prepared by autocombustion of citrate gel. The energy level shift of activator Eu2+and coactivator Dy3+was analyzed according to the emission and the excitation spectra. The band gap change of SrAl2O4and the resulting trap depth change with particle size were discussed on the basis of analyzing the visible spectra, the vacuum ultraviolet (VUV) excitation spectra, and the thermoluminescence (TL) spectra. The fluorescence quenching and the shallow traps originating from surface adsorption or surface defects explain the weak initial persistent phosphorescence and the fast phosphorescence decay in nanometer SrAl2O4:Eu2+, Dy3+. It is confirmed that energy level, band gap, trap depth, defect, and surface adsorption are deeply related with each other in this nanoscale long persistent phosphor.