Synthesis and Luminescence Properties of YNbO4:A (A = Eu3+ and/or Tb3+) Nanocrystalline Phosphors via a Sol–Gel Process

Rare-earth (Eu3+ and/or Tb3+) ions doped YNbO4 phosphors were prepared though a Pechini-type sol–gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy, photoluminescence, and cathodoluminescence spectra were utilized to characterize the synthesized phosphors. XRD reveal that the samples begin to crystallize at 800 °C and pure YNbO4 phase can be obtained at 1000 °C. FE-SEM images indicate that the YNbO4:A (A = Eu3+ and/or Tb3+) samples consist of fine and spherical grains of around 40–80 nm. Under the ultraviolet light (around 255 nm) and low-voltage electron beams, the prepared YNbO4:A (A = Eu3+ and/or Tb3+) phosphors show the characteristic blue broadband emission (from 300 to 500 nm with a maximum around 403 nm) of the YNbO4 host lattice, the characteristic red emission of Eu3+ (5DJ → 7FJ′, J, J′ = 0,1,2,3 transitions) and the characteristic green emission of Tb3+ (5D4 → 7F6,5,4,3 transitions). There exists an energy transfer from th...