Synergistically improving luminescent properties of Eu2+, Dy3+ co-doped melilite with Bi3+ coupling

The improvement of luminescent properties is important for expanding the application of long afterglow phosphor (LAP). Here, the melilite-type Sr 1·97 MgSi 2 O 7 : Eu 2+ 0.01 , Dy 3+ 0.02 LAP was studied with Bi 3+ as the second co-dopant. Both photoluminescence (PL) and thermoluminescence (TL) were improved in terms of intensity and afterglow lifetime when the doping concentration of Bi 3+ exceeded 2.5 mol%, and the optimized point was 3.5 mol%. As compared to the case of Eu 2+ - Dy 3+ double doping, the improved PL of Eu 2+ - Dy 3+ - Bi 3+ triple doping samples was attributed to better photon absorption . The improved TL and afterglow were attributed to the synergistic strengthening density of the traps by Bi 3+ and the deepening of trapping by Dy 3+ , if their distance was sufficient close. As a result, both TL and afterglow optimized at a concentration of 2 mol% Dy 3+ - 3.5 mol% Bi 3+ coupling.