Time-resolved photoluminescence and excited state structure of Bi3+ center in YAlO3

YAlO3:Bi ceramics prepared from the nanopowders synthesized by the sol gel (Pechini) method are studied at 8-400 K by the time-resolved spectroscopy methods. An intense dominant ultraviolet luminescence of YAlO3:Bi is shown to arise from the radiative decay of the metastable and radiative minima of the triplet relaxed excited state (RES) of Bi3+ centers related to the P-3(0), P-3(1) levels of a free Bi3+ ion, respectively. At T< 80K, the radiative transitions from the metastable minima take place. Thermally stimulated nonradiative transitions between the metastable and radiative minima of the triplet RES appear at T> 80K in the temperature dependences of the emission spectrum and decay kinetics. From these dependences, the energy separation between the radiative and metastable minima, and the rates of the radiative and nonradiative transitions from these minima, are determined. The excitation bands of the ultraviolet emission, located at 4.425, around 5.6 eV and at the energy higher than 6 eV, are ascribed to the S-1(0) -> P-3(1), S-1(0) -> P-3(2), and S-1(0) -> P-1(1) transitions of a free Bi3+ ion, respectively. (C) 2014 Elsevier B.V. All rights reserved.