Reddish-orange emitting long-lasting phosphorescence phosphor Ca2Si5N8:Eu2+,Tm3+ has been prepared by solid-state
reaction method using cheaper CaH2 as calcium source. Upon UV light excitation, Ca2Si5N8:Eu2+,Tm3+ phosphor gave a
broad band emission peaking at ca. 600 nm. Furthermore, after irradiation by the UV or visible light (in the range of
250-400 nm) for 3 min, the same colored intense afterglow based on the 4f65d1→4f7 transition of Eu2+ ion was observed
on the phosphor codoped with 0.5 at% of Eu2+ and Tm3+ ions, and its afterglow can be seen with the naked eye in the
dark clearly for more than 1 h after removal of the excitation source. The afterglow decay curve contained fast decay and
slow decay components. The substitution of Mg2+ to Ca2+ ions or addition of excessive Ca2+ ions into the phosphor
matrix to modify the defect environment were effective to improve the afterglow properties.
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