Persistent luminescence of Eu~(2+) doped alkaline earth aluminates, MAl_2O_4:Eu~(2+)

摘要

The polycrystalline Eu~(2+) and RE~(3+) (rare earth) doped alkaline cards aluminates MAl_2O_4:Eu~(2+) ,RE~(3+) (M=Ca and Sr) were prepared by a solid state reaction starting from the corresponding oxides (Al, RE) and carbonates (Ca, Sr). The UV-excited photoluminescence, persistent luminescence (afterglow) and thermoluminescence of these materials was studied and compared. The two spectra (band position and width) were very similar indicating that the luminescent centre is an Eu~(2+) ion in both cases. A slight blue shift was observed in the afterglow emission in some eases. The RE~(3+) co-doping had no effect on the position and shape of the persistent luminescence band but the Nd~(3+) and Dy~(3+) ions enhanced the most the afterglow and thermoluminescence of the CaAl_2O_4:Eu~(2+) and SrAl_2O_4:Eu~(2+) materials, respectively. Easily reducible rare earth ions such as Sm~(3+) and Yb~(3+) suppressed both the afterglow and thermoluminescence of MAl_2O4_:Eu~(2+). Based on these observations, the mechanism of RE~(3+) co-doping is discussed.