Concentration dependence of luminescence properties of GdNbO4:Er3+/Yb3+ synthesized through hydrothermal route

To investigate the concentration dependence of the optical, up-conversion, and photoluminescence properties of phosphors based on GdNbO4 co-doped with Er3+ and Yb3+ an approach through hydro-thermal synthesis route including subsequent heating in air was adopted. A single phase of monoclinic fergusonite-type Gd1.00-(x+y)ErxYbyNbO4 solid solution (x = 0-0.50, y = 0-0.30) was directly formed as nanocrystals by the substitutional incorporation of 0-50 mol% Er3+ and 0-30 mol% Yb3+ under hydrothermal condition at 240 degrees C for 5 h. The nanocrystalline GdNbO4:Er3+/Yb3+ whose crystallite sizes are around 18-38 nm showed the up-converted emission in the green spectral region, 515-565 nm under excitation at wavelengths of 980 nm in addition to the photoluminescence under excitation both at 259 nm and at 377 nm. At the concentration of 20 mol% Er3+ (x = 0.20), the up-converted emission intensity of the Gd1.00-(x+y)ErxYbyNbO4 solid solution became the highest by the incorporation of 20 mol% Yb3+ (y = 0.20). Although the emission intensity of samples changed depending on their concentrations, x and y, the nanocrystalline GdNbO4 co-doped with 5 mol% Er3+ and 20 mol% Yb3+ presented the strongest up-converted emission. (C) 2017 Elsevier B.V. All rights reserved.