Energy transfer from Tb3+ to Eu3+ ions sorbed on SrTiO3 surface

The energy transfer at room temperature between Tb3+ and Eu3+ ions sorbed onto SrTiO3 powders is investigated, using Time-Resolved Laser-induced Fluorescence Spectroscopy (TRLFS). Several published works deal with the energy transfer between two lanthanide ions in co-doped matrices but it is the first time that transfer processes between two lanthanide ions sorbed on a solid surface is reported. The results show that the energy transfer between sorbed Tb3+ and Eu3+ ions on strontium titanate is a non-radiative process and follows a dipole–dipole type interaction. Moreover, the higher the acceptor ions Eu3+ concentration, the more efficient the energy transfer. It is shown that no energy migration between the Tb3+ donor ions occurs. A formalism based on the model of Inokuti–Hirayama is used and allows one to fit the non-exponential Tb3+ fluorescence decay. It is thus possible to evaluate the critical radius (R0) of the influence sphere of the sorbed Tb3+ ions. According to the previous works, two sorption sites are considered for the sorbed rare-earth. The calculated radii are similar to those obtained for other couples of donor–acceptor lanthanide ions reported in the literature.