Formation and roles of point defects in SrAl2O4:Eu2+,Dy3+ phosphors

The SrAl2O4:EU2+,Dy3+ phosphors containing different point defects were synthesized by solid-state reaction method. The roles of crystal point defects in SrAl2O4:Eu2+, Dy3+ phosphors were studied by comparing afterglow decay properties, excitation spectra and thermoluminescence of different samples. The results show that Dy-sr plays an important role in persistent luminescence of SrAl2O4:Eu2+, Dy3+ phosphors. It can serve as an effective electron trap having apprepriate depth for persistent luminescence. V-o can not serve as the electron trap with an appropriate depth, but can increase the trap depth of the Dy-Sr. There is interaction between the Dy3+(Dy-Sr) and the Eu2+(Eu-Sr(x)), and only if the distance between them is close enough, can Dy-Sr become effective electron trap. The V-Sr(") can become hole trap, but the change of its concentration in phosphors does not arouse the obvious change of persistent luminescence.