Luminescent behavior of Tb3+ transitions in green Ba6Ca3Al2Si6O24:Ce3+/ Tb3+/Na+ phosphors

Ba6Ca3Al2Si6O24:Ce3+/Tb3+/Na+ phosphors were prepared via a solid-state reaction at 1150 degrees C in air. In addition to appropriate peak positions, X-ray diffraction analysis also revealed that single-phase phosphors contained a trigonal crystal system with R (3) over bar H symmetry. The particle morphology of the Ba6Ca3Al2Si6O24:Ce3+/Tb3+ phosphors co-doped with Na+ ions was observed by scanning electron microscopy. Multiphonon relaxation and cross relaxation between two adjacent Tb3+ ions in the Ba6Ca3Al2Si6O24 host structure were exploited with examining the excitation and emission photoluminescence spectra of the Ba6-3q/2TbqCa3Al2Si6O24 and Ba6-(q+r)TbqNarCa3Al2Si6O24 phosphors. Co-doping of the Ba6Ca3Al2Si6O24:Tb3+ lattice with Na+ and Ce3+ led to enhanced green emission. The mechanism for the energy transfer from Ce3+ to Tb3+ in the intense green Ba5.85-3q/2Ce0.1TbqCa3Al2Si6O24 and Ba5.8-2qCe0.1TbqNa0.1+qCa3Al2Si6O24 phosphors was determined. Moreover, the desired Commission Internationale de l'Eclairage coordinates of the phosphors were monitored from blue to green regions. Thermal quenching was observed with an increase in temperature from 298 to 448 K, and the activation energy of the Tb3+ transition was calculated. The estimated relative quantum efficiency and internal quantum efficiency were obtained for the Ba5.4Ce0.1Tb0.2Na0.3Ca3Al2Si6O24 phosphors.