Energy transfer mechanisms in the NaBr : Sn2+ : Mn2+ phosphor

Abstract Energy transfer from Sn 2+ to Mn 2+ ions in monocrystalline NaBr codoped with these ions is analyzed in the present investigation. The spectroscopic data obtained clearly indicate that this process takes place at very low concentrations of the dopants, and even after the crystals are subjected to severe quenching treatments, suggesting, therefore, that the impurities are not randomly distributed but rather are forming small Sn–Mn clusters. With the help of Dexter's theory for energy transfer phenomena, it is possible to infer that a short-range interaction mechanism is active in the Sn–Mn clusters. In order to obtain a better understanding of the Sn 2+ →Mn 2+ energy transfer process occurring in NaBr : Sn 2+  : Mn 2+ , we also obtained emission, excitation and lifetime data for the one-activator NaBr : Sn 2+ phosphor.