Host-Sensitized and Tunable Luminescence of GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) Nanocrystalline Phosphors with Abundant Color.

Abstract

Up to now, GdNbO4 has always been regarded as an essentially inert material in the visible region with excitation of UV light and electron beams. Nevertheless, here we demonstrate a new recreating blue emission of GdNbO4 nanocrystalline phosphors with a quantum efficiency of 41.6% and host sensitized luminescence in GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) nanocrystalline phosphors with abundant color in response to UV light and electron beams. The GdNbO4 and GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) nanocrystalline phosphors were synthesized by a Pechini-type sol-gel process. With excitation of UV light and low-voltage electron beams, the obtained GdNbO4 nanocrystalline phosphor presents a strong blue luminescence from 280 to 650 nm centered around 440 nm, and the GdNbO4:Ln3+ nanocrystalline phosphors show both host emission and respective emission lines derived from the characterize f-f transitions of the doping Eu3+, Tb3+, and Tm3+ ions. The luminescence color of GdNbO4:Ln3+ nanocrystalline phosphors can be tuned from blue to green, red, blue-green, orange, pinkish, white, etc. by varying the doping species, concentration, and relative ratio of the codoping rare earth ions in GdNbO4 host lattice. A single-phase white-light-emission has been realized in Eu3+/Tb3+/Tm3+ triply doped GdNbO4 nanocrystalline phosphors. The luminescence properties and mechanisms of GdNbO4 and GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) are updated.