Luminescence properties of Y2WO6:Yb3+/Er3+ with enhanced red emission via upconversion

The Er3+/Yb3+ co-doped Y2WO6 phosphors were prepared via high temperature solid method for the first time. The structure was investigated with X-ray diffraction (XRD). The crystal morphology was observed through scanning electron microscopy (SEM). Under the excitation of 980 nm diode laser, visible up-conversion (UC) emissions were observed in green and red regions. The luminescence study reveals strong S-4(3/2) to I-4(15/2) transition at 545 nm and strong F-4(9/2) to I-4(15/2) transition at 657 nm. The relative intensities ratios of red (510-580 nm) to green (640-690 nm) emissions (R-R/G) reduce when the samples co-doped with Yb3+ ions. The dependence of emission intensity on the pump power indicate that visible UC emissions are governed by two photons, meanwhile three photons process is also involved. For more details, the discussion is made in the energy level diagrams. (C) 2017 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.