New strategy to achieve La2O2CN2:Eu3+ novel luminescent one-dimensional nanostructures
Abstract
La2O3:Eu3+ nanofibers and nanobelts were fabricated by calcination of the respective electrospun PVP/[La(NO3)3 + Eu(NO3)3] composite nanofibers and nanobelts. For the first time, La2O2CN2:Eu3+ nanofibers and nanobelts were successfully prepared via cyanamidation of La2O3:Eu3+ respective nanostructures employing NH3 gas and graphite at high temperature. X-Ray powder diffraction (XRD) analysis indicates that La2O2CN2:Eu3+ nanostructures are tetragonal in structure with space group I4/mmm. Scanning electron microscope (SEM) analysis reveals that the thickness and width of the La2O2CN2:Eu3+ nanobelts are, respectively, ca. 192 nm and 1.67 ± 0.18 μm, and the diameters of La2O2CN2:Eu3+ nanofibers are 173.61 ± 21.61 nm under the 95% confidence level. Photoluminescence (PL) analysis manifests that the La2O2CN2:Eu3+ with different morphologies emits the predominant emission peaks at 614 nm and 622 nm originated from the energy levels transition 5D0 → 7F2 of Eu3+ ions under the excitation of 284 nm ultraviolet light. It is found that the optimum doping molar concentration of Eu3+ ions for La2O2CN2:Eu3+ nanostructures is 3%. La2O2CN2:Eu3+ nanofibers exhibit stronger PL intensity than the nanobelts under the same doping concentration. CIE analysis demonstrates that color-tuned luminescence can be obtained by changing the concentration of doping activator ions and morphologies, which could be applied in the fields of optical telecommunication and optoelectronic devices. The possible formation mechanisms of La2O2CN2:Eu3+ nanofibers and nanobelts are also proposed. More importantly, the new strategy and construct technique are of universal significance to fabricate other rare earth oxycyanamide nanostructures with various morphologies.