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

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