Color-Tunable Luminescence of YNbO4:Ln3+ (Ln3+ = Dy3+ and/or Eu3+) Nanocrystalline Phosphors Prepared by a Sol-Gel Process

A series of YNbO4:Ln(3+) (Ln(3+) = Dy3+ and/or Eu3+) phosphors have been synthesized by a Pechini-type sol-gel method. X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy were utilized to characterize the prepared phosphors. The pure phase of YNbO4 was obtained after annealing at 1000 degrees C. The morphologies of the YNbO4:Ln(3+) (Ln(3+) = Dy3+ and/or Eu3+) phosphors are approximately spherical grains with a diameter of around 40-60 nm. The luminescence properties of the YNbO4:Ln(3+) (Ln(3+) = Dy3+ and/or Eu3+) phosphors were investigated by photo- and cathodoluminescence methods. Under the excitation of UV light and a low-voltage electron beam, the YNbO4:Ln(3+) (Ln(3+) = Dy3+ and/or Eu3+) phosphors obtained show characteristic blue wide-band emission from the NbO4 group, whitish light emission from Dy3+, and red emission from Eu3+. Energy is transferred from the YNbO4 host lattice to the Dy3+ and Eu3+ ions. Single-phase white-light-emision was observed in YNbO4:Dy3+ phosphors under the excitation of UV light and a low-voltage electron beam. The color rendering index of the YNbO4:Dy3+ phosphor can be further improved by co-doping YNbO4:Dy3+ with the Eu3+ ion. The emission color of the YNbO4:Dy3+,Eu3+ phosphors can be simply tuned by changing the relative ratio of the Dy3+/Eu3+ ions. The prepared YNbO4:Dy3+ and YNbO4:Dy3+,Eu3+ phosphors have potential applications in UV white-light-emitting diodes and other optoelectronics display devices.