Energy transfer between Eu~(2+) and Mn~(2+) in long-afterglow phosphor CaAl_2O_4:Eu~(2+), Nd~(3+), and Mn~(2+)

摘要

Long-afterglow phosphor CaAl_2O_4: Eu~(2+), Nd~(3+), and Mn~(2+) were prepared by the solid-state synthesis method. The CaAl_2O_4: Eu~(2+), Nd~(3+), and Mn~(2+) phosphors show two emission bands peaking at around 440 and 545 nm, originating from the allowed f-d transition of Eu~(2+) and the forbidden ~4T_1-~6A_1 transition of Mn~(2+), respectively, under ultraviolet excitation at 340 nm. Spectroscopy and afterglow decay time measurements demonstrate that energy transfer from Eu~(2+) to Mn~(2+). The different colors between photoluminescence and afterglow was analyzed and observed based on energy transfer. Moreover, effects of Mn~(2+) doping on the afterglow properties of CaAl_2O_4: Eu~(2+), Nd~(3+) are explored and explained by thermoluminescence technique.