RE-Doped Ternary Sulfides ALnS2 (A = Rb, K, Na; Ln = La, Gd, Lu, Y) - a New Phosphor Family

Monday, October 12, 2015: 10:00
Phoenix West (Hyatt Regency)
V. Jary (Institute of Physics, Czech Academy of Sciences), L. Havlak, J. Barta (Czech Technical University in Prague.), E. Mihokova, M. Buryi, M. Rejman (Institute of Physics, Czech Academy of Sciences), and M. Nikl (Institute of Physics, Czech Academy of Sciences)
We have recently started to investigate structural, scintillation, luminescence and paramagnetic (in case of Eu2+ doping) properties of the unexplored family of rare earth (RE)-doped ternary sulfides of general formula ALnS2 (A = Rb, K, Na; Ln = La, Gd, Lu, Y), which show prospective application potential in the field of X-ray and solid state white LED phosphors. The X-ray diffraction (XRD) detected only a single crystalline phase of rhombohedral lattice system, except NaLaS2 which has cubic structure. Time-resolved luminescence spectroscopy, XRD and electron paramagnetic resonance were employed to understand the nature of Eu2+ emission centre in these sulfidic hosts and find correlation between structural and optical properties of these materials. Eu2+ and Ce3+ emission features are investigated in a broad temperature and concentration ranges and phenomenological modeling and delayed recombination decay measurements are used to understand better the Eu2+ excited state dynamics. Optical properties of ALnS2 doped by another RE ions are presented as well. Motivating figure 1 shows clear energy shift of the Eu2+ emission spectra maxima with different chemical compositions, peaking from 498 nm (RbLuS2) to 779 nm (NaGdS2).

Figure 1. RT Radioluminescence spectra of Eu2+-doped ALnS2.