Excited State Dynamics of Undoped and Eu³⁺-doped TbAl₃(BO₃)₄ Crystals

Abstract

The room-temperature luminescence spectra and emission decay curves of undoped and Eu3+-doped TbAl3(BO3)4 crystals, grown using the flux growth technique, are presented and discussed. The experimental results show that excitation of the Tb3+ levels gives rise to 5D0 emission from the Eu3+ ion, and therefore non-radiative energy transfer is operative involving the two ions. Analysis of the experimental data indicates that the excitation of the Tb3+ donor ion gives rise to diffusion limited migration of the energy in the 5D4 level of the Tb3+ subset of cations, followed by the energy transfer process populating the 5D0 level of Eu3+. Upon increasing the concentration of the Eu3+ acceptor, the mainly green emission intensity and the decay time of the 5D4 level decrease, while the red emission of 5D0 becomes dominant. The experimental data are interpreted on the basis of the trigonal huntite-type structure of the double borate crystals under investigation.