Energy transfer in Ce and Eu co-doped barium thiogallate: A photoluminescence characterization

In this work we report for the first time the fluorescence properties of Ce3+ single-doped and Ce3+/Eu2+ co-doped BaGa2S4 crystals, studied by means of time resolved measurements. The single-doped samples fluorescence was characterized by the Ce3+ radiative transitions from the 2D level to the 2F5/2 and 2F7/2 levels with a lifetime of 18 ns, and by a radiative transition from the Eg level to the ground state of Ce3+ ions with a lifetime of 11 ns. The co-doped samples fluorescence was characterized by Eu2+ radiative transition from 4f6d state to the ground state with a lifetime of 290 ns. Ce3+ emissions in co-doped samples are strongly quenched and a lifetime of 6 ns is observed. The reported data are discussed in the framework of energy transfer process between Ce and Eu. The rate of the energy transfer was estimated in 7.5 × 107 s-1 with efficiency of 66%.