Persistence energy transfer between inequivalent Eu2+ ions in CaAl2Si2O8:Eu2+

Persistence energy transfer between Eu2+ ions in CaAl2Si2O8:Eu2+ has been observed, which mainly due to the complexity of the system, brought about by the different crystallographic sites. he increase of Eu2+ concentration, a persistent down-converted afterglow from blue to green was observed due to efficient persistence energy transfer from Eu1 to Eu2 which located at inequivalent sites in CaAl2Si2O8:0.19Eu2+. When some of the trapped carries are released from the traps (T1) via thermal activation, they are returned to the excited state of Eu1, and rapidly transfer their energy to Eu2, which contribute to the observation of tunable persistent color.