Temperature-dependent nonradiative energy transfer from Gd3+ to Ce3+ ions in co-doped LuAG:Ce,Gd garnet scintillators

Energy transfer from donor Gd3+ to acceptor Ce3+ ions was studied in low doped lutetium aluminum garnet, LuAG:Ce,Gd. High purity single crystalline films were prepared by liquid phase epitaxy. The mechanism of nonradiative energy transfer from 6PJ (Gd3+) multiplet to crystal field split 5d2 (2D) states of Ce3+ was established as long-range dipole-dipole interaction and the average critical transfer distance between Gd3+ and Ce3+ ions was found ~14 Å at room temperature. It is shown that the single step energy transfer between donor-acceptor pairs is dominant while migration of excitation energy within the donor Gd3+ subsystem is only a small perturbation in the energy transfer mechanism in the studied low doped garnets.