Luminescent performance of Ca2SnO4:Tb3+ phosphors with Li+ co-doping

Long afterglow phosphors Ca2SnO4:Tb3+, Li+ with a green light were successfully synthesized by solid-state reaction, and their phase composition and luminescent property also studied using X-ray powder diffraction (XRD), photoluminescence (PL) and afterglow decay measurement. The results show that adding a small amount of Li+ ions does not have a significant effect on the crystal structure of Ca2SnO4:Tb3+, and that Ca2SnO4:Tb3+, Li+ samples are single phase of solid solutions. Their luminescent properties are strongly dependent on Li+ doping modes. The distortion of host lattice and change of the local crystal field symmetry around Tb3+ enhanced their emission intensity, while the formation of oxygen vacancy and the suitable depth traps improved their afterglow performance; but the association of interstitial Li+ (Li-i) with Ca2+ vacancy (V ''(ca)), and excessive Li+ ions would worsen their phosphorescence. Their afterglow mechanism was proposed.