Enhanced self-activated far-red photoluminescence from Sr3LiSbO6 phosphors by Gd3+ doping for plant growth

Sr 3 LiSbO 6 phosphors were prepared by high temperature solid state reaction method. The crystal phase, morphology and optical properties were characterized by X-ray powder diffraction spectroscopy, scanning electronic microscope, absorption and photoluminescence (PL) spectra. The XRD Rietveld refinement was performed to obtain the detailed crystal structure of Sr 3 LiSbO 6 . The electronic structure was analyzed by density functional theory (DFT) calculation. Sr 3 LiSbO 6 possessed indirect band structure and the band-gap were determined to be 3.17 eV. Self-activated far-red emissions at 630–800 nm were detected under the excitation at 340 nm, which was proposed to originate from the transition between interstitial oxygen defective state to six hybrid 4d 10 5s 0 states of Sb 5+ according to the results of PL spectra of samples annealed at different atmospheres. The PL intensity can be significantly enhanced by 2.9 times after doping 2 mol% Gd 3+ ions in Sr 3 LiSbO 6 . The internal quantum efficiency of Sr 3 LiSbO 6 :2 mol%Gd 3+ was determined to be 25.2%. The influence of the Gd 3+ doping on the self-activated PL lifetimes of Sr 3 LiSbO 6 and the thermal quenching property of Sr 3 LiSbO 6 :2 mol%Gd 3+ was studied.