Events

Institute of Low Temperature and Structure Research PAS Seminar

Tb³⁺→Eu³⁺ energy transfer in oxide luminescent materials: the role of the donor concentration and of the crystal structure

Prof. Marco Bettinelli

Uniwersytet Werona, Włochy

This talk will discuss energy transfer processes involving trivalent lanthanide ions (Ln3+). After a short introduction presenting the basic concepts ruling non-radiative energy transfer in inorganic materials, the presentation will focus on materials fully concentrated with respect to the sensitizer ion Tb3+ and containing relatively small amounts of the activator ion Eu3+. Two different classes of inorganic crystal hosts will be considered, namely the cubic eulytite phosphates M3Ln(PO4)3 (M=Sr, Ba) and the trigonal huntite borates LnAl3(BO3)4. The optical spectroscopy and excited state dynamics of these materials will be presented and discussed, and the nature of the energy transfer analysed. The Tb3+→Eu3+ transfer of excitation occurs in all cases in the presence of efficient energy migration among the Tb3+ donor ions, making the overall process highly efficient. By changing the distance between nearest neighbour ions and the Eu3+ concentration, it is possible to obtain light emission that is in some cases finely tunable from the green to the orange and finally to the red, upon excitation in the near UV.