Luminescence investigations of Ce3+ doped CaS nanophosphors

Ce3+ doped CaS nanophosphors were synthesized using the chemical co-precipitation method. The samples were characterized using X-ray diffraction, transmission electron microscopy, electron dispersive X-ray spectroscopy, UV–vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The PL emission peaks of both the 2D(5d) → 2F5/2 (4f) and 2D(5d) → 2F7/2(4f) transitions of the Ce3+ ion were blue-shifted from the normal PL emission of bulk CaS:Ce at 517 nm, suggesting that the particle sizes of CaS:Ce phosphors synthesized in this study were in the nanometer scale. The effect of different dopant concentrations on the PL emission intensity was also investigated. The maximum PL emission intensity was observed when CaS was doped with 0.04 mol% of the Ce3+. Compared with commercial phosphors (CaS:Ce), the decay lifetime of the present samples was found to be longer in the order of a few milliseconds probably due to increased radiative relaxation processes.