Fabrication of Er3+-doped LaOCl nanostructures with upconversion and near-infrared luminescence performances

Abstract

LaOCl:Er3+ nanofibers and nanobelts were prepared by electrospinning combined with a double-crucible chlorination technique using NH4Cl powders as chlorinating agent. X-ray powder diffraction analysis indicated that LaOCl:Er3+ nanostructures were tetragonal with space group P4/nmm. Scanning electron microscope analysis and histograms revealed that diameter of LaOCl:Er3+ nanofibers and the width of nanobelts respectively were 161.15 ± 18.11 nm and 6.11 ± 0.19 μm under the 95 % confidence level, and the thickness of nanobelts was 116 nm. Up-conversion (UC) emission spectra analysis manifested that LaOCl:Er3+ nanostructures exhibited strong green and red UC emission centering at 525, 548 and 671 nm, respectively attributed to 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4Il5/2 energy levels transitions of Er3+ ions under the excitation of a 980-nm diode laser. It was found that the relative intensities of green and red emissions vary obviously with the changing of concentration of Er3+ ions, and the optimum molar percentage of Er3+/(La3++Er3+) ions was 5 % in the LaOCl:Er3+ nanostructures. The LaOCl:x %Er3+ nanobelts have higher UC emission (both red and green) intensity than the counterpart nanofibers. Moreover, the near-infrared characteristic emissions of LaOCl:Er3+ nanostructures were achieved under the excitation of a 532-nm laser. Commission Internationale de L’Eclairage analysis demonstrated that color-tuned luminescence can be obtained by changing doping concentration of Er3+ ions, which could be applied in the fields of optical telecommunication and optoelectronic devices. The UC luminescent mechanism of LaOCl:Er3+ nanostructures were also proposed.