The synthesis and luminescent properties of Dy/Re (Re = Tb or Eu) co-doped Gd2(WO4)3 phosphor with tunable color via energy transfer

Abstract

The new systems of the (Gd0.95-xDy0.05Tbx)2(WO4)3 (x = 0–0.1) and (Gd0.95-yDy0.05Euy)2(WO4)3 (y = 0–0.2) phosphors have been successfully obtained using the hydrothermal method at 900 °C in this work. The crystal structure, morphology, PL/PLE spectra, fluorescence and decay analysis have been studied in detail via the combined techniques of XRD, FE-SEM, PLE/PL spectra and decay kinetic. The phase-pure of the (Gd0.95-xDy0.05Tbx)2(WO4)3 and (Gd0.95-yDy0.05Euy)2(WO4)3 with good dispersions have been formed at the lower sintering temperature of 900 °C. Under 273 nm and 270 nm excitation (the 6P7/2→8S7/2 transitions of Gd3+), the Gd2(WO4)3:Dy3+/Tb3+ and Gd2(WO4)3:Dy3+/Eu3+ phosphors exhibit both Dy3+ (yellow, at 574 nm) and Tb3+ (green, at 547 nm) as well as Dy3+ (yellow, at 574 nm) and Eu3+ (red, at 616 nm) emissions, respectively. The presences of WO42-, Gd3+ and Dy3+ excitation bands on the PLE spectra by monitoring the Tb3+ and Eu3+ emissions directly provide an evidence of energy transfer of WO42-→Tb3+, Gd3+→Tb3+ and Dy3+→Tb3+, as well as WO42-→Eu3+, Gd3+→Eu3+ and Dy3+→Eu3+, respectively. The quenching concentrations of both two systems are determined to be 7 at% (x = 0.07 for Tb3+) and 10 at% (y = 0.10 for Eu3+), and the quenching mechanisms of both two systems are mainly due to the Tb3+-Tb3+ and Eu3+-Eu3+ energy transfers, respectively. The color-tunable emission can be achieved though adjusting the relative content ratios of Dy3+/Tb3+ or Dy3+/Eu3+, which has been verified by the CIE chromaticity coordinates analysis. The energy transfer efficiencies of Dy3+→Tb3+ and Dy3+→Eu3+ have been calculated, and the energy transfer mechanisms have been analyzed in detail. The (Gd0.95-xDy0.05Tbx)2(WO4)3 and (Gd0.95-yDy0.05Euy)2(WO4)3 phosphors with color-tunable emission may have a potential application for w-LEDs.