Controlled synthesis and optical properties of Ce3+/Tb3+ co-doped BaGdF5 nanocrystals

Based on a hydrothermal method, the Ce3+/Tb3+ co-doped BaGdF5 nanocrystals were synthesized by controlling the introduction concentration of Ba2+ and Gd3+. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) images, photoluminescence (PL) excitation, and emission spectra, as well as the photoluminescence dynamic decay curves. With the increase of the Ba2+ concentration in the synthesis procedure, the positions of diffraction peaks of XRD patterns move toward lower degree, and the case of the samples synthesized with the increase of the Gd3+ concentration is contrary, which consists well with each other. The FE-SEM images suggest that the BaGdF5 nanocrystals are in spherical morphology, and the average diameters decrease with the increase of Ba2+ or Gd3+ concentration. For the 4f-5d transition of Ce3+ is sensitive to the environment of local lattice, the PL excitation and emission spectra of the samples are different. The 4f-4f transition of Tb3+ also presents different optical properties in different host lattices. The variations of the optical properties of Ce3+ and Tb3+ as well as the lifetime of the D-5(4) -> F-7(5) emission of Tb3+ are also consistent well with each other in the two series of samples.