Synthesis and luminescence properties of YF3:Eu3+ hollow nanofibers via the combination of electrospinning with fluorination technique

Y2O3:Eu3+ hollow nanofibers were prepared by calcination of the electrospun PVP/[Y(NO3)(3) + Eu(NO3)(3)] composite nanofibers, and then YF3:Eu3+ hollow nanofibers were successfully synthesized by fluorination of the as-prepared Y2O3:Eu3+ hollow nanofibers via a double-crucible method using NH4HF2 as fluorinating agent for the first time. X-ray diffraction (XRD) analysis showed that YF3:Eu3+ hollow nanofibers were pure orthorhombic structure with space group Pnma. Transmission electron microscope (TEM) and scanning electron microscope (SEM) observations indicated that as-obtained YF3:Eu3+ nanofibers were hollow-centered structure with the mean diameter of 197 +/- 34 nm. Under the excitation of 394 nm ultraviolet light, YF3:Eu3+ hollow nanofibers exhibited red emissions of predominant peaks at 587 nm and 593 nm originating from D-5(0) -> F-7(1) transition of the Eu3+ ions, which suggested Eu3+ ion in YF3 crystal is at a site of C-2 symmetry. Moreover, the emitting colors of YF3:Eu3+ hollow nanofibers are located in the red region in CIE chromaticity coordinates diagram. The luminescent intensity of YF3:Eu3+ hollow nanofibers was increased remarkably with the increasing doping concentration of Eu3+ ions and reached a maximum at 9 mol% of Eu3+. The possible formation mechanism of YF3:Eu3+ hollow nanofibers was also discussed. This preparation technique could be applied to prepare other rare earth fluoride hollow nanofibers. (c) 2012 Elsevier B.V. All rights reserved.