Luminescence characteristics of Pb~(3+) centres in undoped and Ce~(3+) -doped Lu_3Al_5O_(12) single-crystalline films and Pb~(2+) → Ce~(3+) energy transfer processes

摘要

At 4.2-350 K, the steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics were studied under excitation in the 2.5-15eV energy range for the undoped and Ce~(3+) -doped Lu_3Al_5O_(12) (LuAG) single-crystalline films grown by liquid phase epitaxy method from the PbO-based flux. The spectral bands arising from the single Pb~(2+)-based centres were identified. The processes of energy transfer from the host lattice to Pb~(2+) and Ce~(3+) ions and from Pb~(2+) to Ce~(3+) ions were investigated. Competition between Pb~(2+) and Ce~(3+) ions in the processes of energy transfer from the LuAG crystal lattice was evidenced especially in the exciton absorption region. Due to overlap of the 3.61 eV emission band of Pb~(2+) centres with the 3.6eV absorption band of Ce~(3+) centres, an effective nonradiative energy transfer from Pb~(2+) ions to Ce~(3+) ions takes place, resulting in the appearance of slower component in the luminescence decay kinetics of Ce~(3+) centres and decrease of the Ce~(3+)-related luminescence intensity.