Synthesis and luminescence properties of Yb3+-Er3+ co-doped LaOCl nanostructures

LaOCl:Yb3+, Er3+ nanofibers and hollow nanofibers were prepared by electrospinning combined with a double-crucible chlorination technique using NH4Cl as chlorinating agent. X-ray powder diffraction analysis indicated that LaOCl:Yb3+, Er3+ nanostructures were tetragonal with space group P4/nmm. Scanning electron microscope analysis and histograms revealed that diameters of LaOCl:Yb3+, Er3+ nanofibers and hollow nanofibers, respectively, were 117.87 +/- A 15.48 and 141.09 +/- A 17.10 nm under the 95 % confidence level. Up-conversion (UC) emission spectra analysis manifested that LaOCl:Yb3+, Er3+ nanostructures exhibited strong green and red UC emission centering at 526, 548, and 671 nm, respectively, attributed to H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(l5/2) 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 addition of Yb3+ ions, and the optimized molar ratio of Yb3+ to Er3+ was 10:1 in the as-prepared nanofibers. Moreover, the near-infrared characteristic emissions of LaOCl:Yb3+, Er3+ nanostructures were achieved under the excitation of a 532-nm laser. CIE analysis demonstrated that color-tuned luminescence can be obtained by changing doping concentration of Yb3+ (and/or Er3+) ions and morphologies of nanomaterials, which could be applied in the fields of optical telecommunication and optoelectronic devices. The UC luminescent mechanism and the formation mechanisms of LaOCl:Yb3+, Er3+ nanofibers and hollow nanofibers were also proposed.