Energy transfer in Sr0.6Ba0.4Nb2O6 through its ferroelectric phase transition

Resonant Nd3+ -> Yb3+ energy-transfer in the Nd3+ and Yb3+ co-doped Sr0.6Ba0.4(NbO3)(2) (SBN) crystal is investigated by using pulsed and steady state laser spectroscopy. Spectroscopic data revealed that the energy transfer occurs via a non-radiative process. The efficiency of this energy transfer was estimated from spectral data in around 35%. Back energy transfer is not observed at the 295-415 K temperature range. A marked reduction in the luminescence intensity of Yb3+ ions directly excited into their F-2(7/2) -> F-2(5/2) transition, taking place at around 345 K, is due to the ferro to paraelectric phase transition in SBN. This thermal behavior, which is not clearly manifested when Yb3+ ions are excited via Nd3+ ions, has been explained in terms of structural changes taking place around the Yb3+ ions when the crystal becomes non-polar.