Optical properties and Judd–Ofelt analysis of Sm3+ ions in Sm2O2S: Reddish-orange emission and thermal stability

Abstract The thermal decomposition of hydrated samarium sulfate in CO and air atmosphere produced samarium oxysulfide (Sm2O2S) and oxysulfate (Sm2O2SO4), respectively, which were characterized by FTIR, Raman spectroscopy, X-ray diffraction and scanning electron microscopy. An efficient reddish-orange emission was displayed by the Sm2O2S under excitation at 466 nm (6H5/2 → 4I13/2), arising from the 4G5/2 → 6H5/2 (572 nm), 4G5/2 → 6H7/2 (604 nm), and 4G5/2 → 6H9/2 (653 nm) intraconfigurational transitions of the Sm3+ ion. The experimental intensity parameters (Ω2, Ω4, and Ω6) and quantum efficiency ( η ) were calculated by applying Judd–Ofelt approach to the 4f-4f intraconfigurational transitions of the Sm3+ ion. The thermal stability of the samarium oxysulfide/oxysulfate was investigated systematically by TG/DTG analyses, suggesting the formation of trigonal Sm2O2S at 1100 K and monochlinic crystalline phase for Sm2O2SO4 at 1300 K temperature. Based on these spectroscopic results, it is suggested that the as prepared Sm2O2S can be promising reddish-orange-emitting phosphor for UV based White light-emitting diodes.