Structure and luminescence properties of Sr4Al14O25:Eu2+, Dy3+ by Ca2+ doping

The rare-earth doped strontium aluminate phosphors SrxCa4-xAl14O25:Eu2+,Dy3+（x＝0，0.8，1.6，2.4，3.2，4） were synthesized by a high temperature solid-state reaction method. The X-ray diffraction studies show that phase of the phosphors is orthorhombic Sr4Al14O25 for x4O7 for x > 2.4. The results indicate that the phase structure of the samples changes from Sr4Al14O25 to CaAl4O7 when the value of x changes from 0 to 4. In addition, a blue shift was found in the emission spectra due to the change in nature of the Eu2+ surroundings. The decay characteristics show that the phosphor samples with different Ca2+ contents have different afterglow time, and the afterglow time also changes with the value of x. The measurement of thermoluminescence reveals that the trap depth of the phosphor samples with different Ca2+ contents is different. The samples with deeper traps have longer afterglow time.