Optical properties of sol-gel derived Sr_2SiO_4: Dy~(3+) - Photo and thermally stimulated luminescence

摘要

Trivalent dysprosium-doped strontium silicate (Sr_2SiO_4) phosphors were prepared by sol-gel synthesis using tetra ethyl orthosilicate (TEOS) as precursor. The synthesis temperature could be brought down to 600 ℃ for formation of a single phase sample. The material was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), photoluminescence (PL), and thermally stimulated luminescence (TSL). The luminescence study revealed strong ~4F_(9/2)→ ~6H_(13/2) transition at 577 nm (yellow), strong ~4F_(9/2)→ ~6H_(15/2) transition at 482 nm (blue) and weak ~4F_(9/2)→ ~6H_(11/2) transition at 677 nm (red), when excited by 250 nm (Charge transfer band, CTB) or 352 nm (f-f band). The concentration of the dopant ion and the temperature of annealing were optimized for maximum PL intensity. The critical energy-transfer distance for the Dy~(3+) ions was evaluated based on which, the quenching mechanism was verified to be a multipole-multipole interaction. The thermally stimulated luminescence studies of Sr_2SiO_4:Dy~(3+) sample showed main TSL glow peak at 413 K. The trap parameters namely activation energy (E), order of kinetics (b), and frequency factor (s) for this peak were determined using glow curve shape method.