Luminescence of lead-related centres in single crystalline films of Lu2SiO5

The steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics of nominally undoped Lu2SiO5 single crystalline films (SCFs) grown by the liquid phase epitaxy method from the PbO-based flux are studied in the range 4.2-300 K. Due to the preparation method, the films contain lead ions. Luminescence characteristics of Pb-related centres of different types are identified. A weak 3.65 eV emission is ascribed to the radiative decay of the triplet relaxed excited state (RES) of Pb2+ ions substituting for Lu3+ ions in the Lu1 lattice sites of the X-2 structure. Possible origins of the intense complex lead-related approximate to 2.8 eV emission are discussed. We propose phenomenological models describing the excited-state dynamics of the studied luminescence centres. We also determine the characteristic parameters of the corresponding RESs, in particular, the energy separations between the excited states and the rates of the radiative and non-radiative transitions from these states.