Photoluminescent properties of near-infrared excited blue emission in Yb, Tm co-doped LaGaO3 phosphors

LaGaO3:Tm3+, Yb3+ powder with different Yb3+ contents (0-~0.15 mol) was synthesized by a conventional solid-state reaction. The structure, morphology and chemical analysis of the as-prepared phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques, respectively. The photoluminescence properties of the as-prepared powder samples were studied. The spectrum consisted of 1G4→3H6, weak 1G4→3F4, and intense 3H4→3H6 transition bands within the f12 configuration of Tm3+, together with the 2F5/2→2F7/2 transition of Yb3+. Up-converted emission of LaGaO3:Tm3+, Yb3+ powders was observed under laser diode excitation of 975 nm. Obvious differences in up-converted emission spectra among the as-obtained products were observed, and possible reasons were discussed. The corresponding up-conversion mechanism was also proposed.