Local coordination, electronic structure, and thermal quenching of Ce 3+ in isostructural Sr 2 GdAlO 5 and Sr 3 AlO 4 F phosphors

Sr 2 GdAlO 5 :Ce and Sr 3 AlO 4 F:Ce are isostructural phosphors in which the Ce 3+ 4 f ‐5 d 1 transition can be efficiently excited by a photon with energy lower than 3.1 eV . Herein, we analyze the crystal chemistry of the Ce 3+ local coordination, compare the thermal quenching behavior and construct the electronic structure of Ce 3+ in them. The Rietveld refinement on two occupancy models suggests that Gd 3+ only occupies the 8 h site in Sr 2 GdAlO 5 ; this provides a hint on the preferred occupancy of dopant Ce 3+ in this site. The large crystal filed splitting of Ce 8 h is mainly due to the fact that the 8 h site is bonded to two oxygen with relatively short d S r/Gd‐O and forms a quasi‐square antiprism which experiences a large distortion. The Ce 3+ 5 d ‐4 f luminescence in Sr 3 AlO 4 F is much more stable against thermal quenching than that in Sr 2 GdAlO 5 , as evidenced by the temperature‐dependent luminescence intensity and luminescence decay studies. The energy of the O 2− ‐Eu 3+/2+ and O 2− ‐Ce 4+/3+ charge transfer as well as bandgap were estimated and the electronic structure of Ce 3+ were constructed. A larger energy barrier Δ E dC between the Ce 3+ 5 d 1 level and the conduction band bottom in Sr 3 AlO 4 F is seen from the Vacuum Referred Binding Energy ( VRBE ) diagrams which explains the higher thermal quenching temperature by thermal ionization model.