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

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 D-5(0) 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 D-5(4) level of the Tb3+ subset of cations, followed by the energy transfer process populating the D-5(0) level of Eu3+. Upon increasing the concentration of the Eu3+ acceptor, the mainly green emission intensity and the decay time of the D-5(4) level decrease, whilst the red emission of D-5(0) becomes dominant. The experimental data are interpreted on the basis of the trigonal huntite-type structure of the double borate crystals under investigation.