Photoluminescence and thermoluminescence of Ce3+ and Eu2+ in Ca2Al2SiO7 matrix

The Ca2Al2SiO7 samples doped with Ce3+ and Eu2+ are synthesized via a high temperature solid-state reaction. Ca2Al2SiO7: Ce3+ emits a strong UV–violet emission while Ca2Al2SiO7: Eu2+ emits a blue–green emission. The Stokes shift of the latter is greater due to a stronger crystal repulsion from ligands to Eu2+ ions. Ca2Al2SiO7: Ce3+ exhibits a stronger initial intensity and longer duration of afterglow due to the higher liberated probability of the trapped carriers. The thermoluminescence curves reveal that at least three traps exist in the phosphors. Ca2+ vacancies may enhance the electron trapping and then lead to a stronger afterglow. A possible explanation will be provided.