Upconversion luminescence of Ba(MoO_4)_h(WO_4)_(1-h):Yb~(3+)/Er~(3+) nanocrystals synthesized through hydrothermal method

摘要

A series of Yb~(3+)/Er~(3+) co-doped Ba(MoO_4)_h(WO_4)_(1-h), upconversion nanocrystals (UCNCs) were prepared via hydrothermal method. The effects of different concentration ratios of Yb~(3+)/Er~(3+) and Mo_4O~(2-)/WO_4~(2-) on the upconversion luminescence were investigated, and the optimum doping concentrations of Yb~(3+) and Er~(3+) in the Ba(MoO_4)_(0.5)(WO_4)_(0.5) host were found to be 3 mol% and 1 mol%, respectively. Structure of Ba(MoO_4)_(0.5)(WO_4)_(0.5):0.03Yb~(3+)/0.01Er~(3+) was identified as the tetragonal in the X-ray diffraction (XRD) results and the particle size observed in the scanning electron microscope (SEM) was about 40 nm. Under excitation of 980 nm semiconductor laser, three emission bands centered at 528, 550 and 660 nm, originating from ~2H_(11/2)→ ~4I_(15/2), ~4S_(3/2) → ~4I_(15/2) and ~4F_(9/2) → ~4I_(15/2) transitions of Er~(3+) ion, respectively, were observed for Ba(MoO_4)_(0.5)(WO_4)_(0.5):0.03Yb~(3+)/0.01Er~(3+). The pump power dependence research suggested that these bands arise due to two-photon absorption. The variation of CIE coordinate at different excitation powers was observed.