Synthesis and upconversion luminescence properties of YF3:Yb3+/Er3+ hollow nanofibers derived from Y2O3:Yb3+/Er3+ hollow nanofibers

Abstract

YF3:Yb3+/Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Yb3+/Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Yb(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction, scanning electron microscope, transmission electron microscope, and fluorescence spectrometer. YF3:Yb3+/Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with mean diameter of 174 ± 22 nm, and YF3:Yb3+/Er3+ hollow nanofibers are composed of nanoparticles with size in the range of 30–60 nm. Upconversion emission spectrum analysis manifested that YF3:Yb3+/Er3+ hollow nanofibers emitted strong green and weak red upconversion emissions centering at 523, 545, and 654 nm, respectively. The green and red emissions were, respectively, originated from 2H11/2/4S3/2 → 4I15/2 and 4F9/2 → 4Il5/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Yb3+/Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers. YF3:Yb3+/Er3+ hollow nanofibers with orthorhombic structure were synthesized by fluorination of the electrospun Y2O3:Yb3+/Er3+ hollow nanofibers via a double-crucible method using NH4HF2 as fluorinating agent. The mean diameter of YF3:Yb3+/Er3+ hollow nanofibers was 174 ± 22 nm. The fluorination method we proposed here has been proved to be an important method, as it can not only retain the morphology of Y2O3:Yb3+/Er3+ hollow nanofibers, but also can fabricate YF3:Yb3+/Er3+ hollow nanofibers with pure orthorhombic phase at low temperature. YF3:Yb3+/Er3+ hollow nanofibers showed excellent upconversion luminescent properties. A possible formation mechanism of YF3:Yb3+/Er3+ hollow nanofibers was also proposed.