Effect of temperature on the luminescence and decay behavior of divalent europium in lithium barium borate

The optical properties of LiBaBO3 doped with Eu2+ are investigated in the temperature regime between 10 and 525 K for the first time. At room temperature (RT), a broad emission band peaking around 485 nm is observed. The emission is ascribed to the 4f65d1 4f7 transition on Eu2+. The excitation spectra consist of broad bands between 220 and 450 nm. The emission intensity shows no remarkable decline at lower temperatures; although it decreases drastically at higher temperatures. The Stokes shift is calculated to be 0.52 eV. The thermal activation of an electron from the Eu2+ excited state to the conduction band is responsible for the thermal quenching behavior in LiBaBO3:Eu system. The energy gap EA for the best fit of decay time is 0.38 eV.