Controllable fabrication and broadband near-infrared luminescence of various Ni2+-activated ZnAl2O4nanostructures by a single-nozzle electrospinning technique

Abstract

By finely tuning the electrospun parameters (feeding rate of solution, working voltage and distance, etc.) and concentration of inorganic salts, various ZnAl₂O₄ nanostructures (nanoparticles, nanonecklaces, nanofibers, nanotubes and hollow micromelts) were controllably synthesized by a single-nozzle electrospinning technique. The formation mechanisms of different ZnAl₂O₄ nanostructures, including ‘oriented attachment’ mechanism, ‘gas-push’ mechanism, etc., were proposed to elucidate the morphology of the nanostructures and microstructure evolvement process. The morphology and microstructure of calcined electrospun nanostructures were considered to be mainly dependent on two factors, i.e. concentration of inorganic salts and size of as-prepared electrospun nanofibers. Using Ni²⁺ ions as activators, broadband near infrared (NIR) emission covering 1000–1400 nm peaking at about 1176 nm was detected in Ni²⁺-doped ZnAl₂O₄ nanostructures. The broadband NIR emission at around 1.3 μm optical communication window with a long lifetime of ∼640 μs makes Ni²⁺-doped ZnAl₂O₄ nanostructures as a promising candidate for micro/nano-broadband optical amplifiers, fibers, etc.