Effect of Tb3+ concentration in the visible emission of terbium-doped gadolinium oxysulfide microspheres

Abstract Experimental data obtained from optical characterization of Gd 2 O 2 S:Tb 3+ microspheres were compared with a rate-equation model in order to understand and simulate the emission intensity and color tonality as a function of Tb 3+ concentration. The microparticles were prepared by hydrothermal synthesis and characterized by TEM and XRD to confirm spherical microparticles with a hexagonal lattice. Furthermore, fluorescent spectroscopy and rate equation model revealed that the direct energy transfer between Gd 3+ →Tb 3+ ions and the migration of the excitation energy between Tb 3+ play an important role in the luminescence intensity, while the color tonality is mainly governed by the non-radiative relaxation processes between Tb 3+ at low concentrations. Finally, our results suggest that the rate equation model provides an efficient alternative to estimate theoretically the maximum doping concentration in oxysulfides before they present quenching of luminescence.