Temperature evolution of the luminescence decay of Sr0.33Ba0.67Nb2O6 : Pr3+

This article presents a spectroscopic investigation of Sr0.33Ba0.67(NbO2)3, doped with 1 mol% of Pr3+. Photoluminescence and luminescence kinetics were measured at different temperatures at ambient (ferroelectric phase) and 76 kbar pressures (paraelectric phase). The photoluminescence spectrum is dominated by 1D2→3H4 transition of Pr3+ in both phases. At ambient pressure when the system is excited with UV radiation, the intensity of dominant 1D2→3H4 emission evidently increases in the 200–293 K temperature range. This effect is attributed to enhancement of the excitation of the 1D2 state through the praseodymium trapped exciton state, which at higher temperatures does not populate the higher lying 3P0 state. Additionally, under UV radiation the material exhibits afterglow luminescence activated by temperature that can also have an impact on the increase of the 1D2 emission. We propose that the afterglow luminescence is related to the existence of electron traps. At a pressure of 76 kbar the depth of the electron traps decreases in comparison to the ones observed at ambient pressure. However, the phase transition does not change the number of electron traps. (papers)