Optical properties of sol–gel derived Sr2SiO4:Dy3+ – Photo and thermally stimulated luminescence

Abstract

Trivalent dysprosium-doped strontium silicate (Sr2SiO4) phosphors were prepared by sol–gel synthesis using tetra ethyl orthosilicate (TEOS) as precursor. The synthesis temperature could be brought down to 600°C 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 4F9/2→6H13/2 transition at 577nm (yellow), strong 4F9/2→6H15/2 transition at 482nm (blue) and weak 4F9/2→6H11/2 transition at 677nm (red), when excited by 250nm (Charge transfer band, CTB) or 352nm (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 Dy3+ ions was evaluated based on which, the quenching mechanism was verified to be a multipole–multipole interaction. The thermally stimulated luminescence studies of Sr2SiO4:Dy3+ sample showed main TSL glow peak at 413K. 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.