Luminescence of dimer lead centers in aluminium perovskites and garnets

Steady-state emission and excitation spectra and luminescence decay kinetics were studied at 80-300 K under excitation in the 2.5-6.0 eV energy range for undoped and Ce3+-doped aluminium garnet (Lu3Al5O12, Y3Al5O12) and aluminium perovskite (LuAlO3, YAlO3) single crystalline films (SCF) grown by Liquid Phase Epitaxy method from the PbO-based flux. The aim of the work was to identify spectral bands, arising from lead-induced centers of different types, and to clarify their influence on scintillation characteristics of Ce3+ centers. It was found that in the perovskite SCF studied, the concentration of single Pb2+-based centers is comparatively small. In the SCF of garnets, in YAG SCF their concentration is considerably smaller than in LuAG SCF. The lead-induced emission at about 3.1-3.2 eV excited around 3.9 eV was observed in all the SCF studied and ascribed to the dimer lead centers of the type of {Pb2+ - oxygen vacancy - Pb2+}. In Ce3+-doped perovskite SCF, due to a strong overlap of the excitation band of the dimer centers and the emission band of Ce3+ centers, a considerable influence of dimer lead centers on the scintillation characteristics of these materials is expected. In the SCF of garnets, the influence of dimer lead centers on the characteristics of Ce3+ centers is negligible. (c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim