The roles of Eu 2+ and Dy 3+ in the blue long-lasting phosphor Sr 2MgSi 2O 7: Eu 2+, Dy 3+

Abstract

The luminescent properties of the undoped, the Eu 2+ or Dy 3+ singly doped as well as Eu 2+ and Dy 3+ codoped Sr 2MgSi 2O 7, were investigated using synchrotron radiation and xenon or mercury lamp as excitation source. Under 172 nm excitation, besides the emission band peaked at 465 nm from Eu 2+ in Sr 2MgSi 2O 7:Eu 2+, Dy 3+, there are evident emission lines at 487 and 575 nm from intraconfigurational 4f transitions of Dy 3+. After the UV excitation, the peak temperatures of thermoluminescence curves were at ∼65 °C for Sr 2MgSi 2O 7:Eu 2+ and ∼120 °C for Sr 2MgSi 2O 7: Dy 3+. Afterglow emission spectra peaking at 465 nm were increased with rising temperature from 180 K to room temperature. The results show that the role of Eu 2+ in Sr 2MgSi 2O 7:Eu 2+, Dy 3+ is not only the luminescence center, but also a trap center. On the contrary, the role of Dy 3+ ions can be not only as a trap center, but also as a luminescence center.