Controlled synthesis and tunable photoluminescence properties of LaOBr:Eu³⁺ nanostructures

Eu³⁺ doped lanthanum oxybromide (LaOBr) nanostructures including nanofibers, nanoribbons, and hollow nanofibers were fabricated for the first time via calcining the electrospun PVP/[La(NO₃)₃+Eu(NO₃)₃+NH₄Br] composites. X-ray diffraction analysis results showed that LaOBr:Eu³⁺ nanostructures were tetragonal in structure with space group of P4/nmm. The morphologies and sizes of the LaOBr:Eu³⁺ nanostructures were studied by scanning electron microscope and transmission electron microscope. The mean diameter of the nanofibers and hollow nanofibers, and the width of nanoribbons are 118.02 ± 14.21, 115.84 ± 13.37 nm, and 1.56 ± 0.25 μm, respectively. Under the excitation of 289 nm ultraviolet light, LaOBr:Eu³⁺ nanostructures exhibit the red emissions of predominant peak at 618 nm, which is ascribed to the ⁵D₀ → ⁷F₂ transition of the Eu³⁺ ions. It is found that the optimum doping concentration of the Eu³⁺ ions in the LaOBr:Eu³⁺ nanofibers is 5 %. Interestingly, we found that the luminescence intensity of nanofibers is obviously greater than that of the hollow nanofibers and nanoribbons for LaOBr:Eu³⁺ under the same measuring conditions. Moreover, the color emissions of LaOBr:Eu³⁺ nanostructures can be tuned by adjusting the concentration of Eu³⁺ and the morphologies of nanomaterials. The obtained LaOBr:Eu³⁺ nanostructures may be promising nanomaterials for applications in the fields of light display systems and optoelectronic devices.