Nucleation control and growth mechanism of pure α-Bi2O3 nanowires

Pure α-Bi2O3 nanowires, with diameters 200-500 nm and lengths of 10-20 μm, were successfully synthesized by a catalysts-driven vapor transport method. X-ray diffraction studies show that the α-Bi2O3 nanowires are single phase contains no secondary phase. Transmission electron microscopy studies combined with a selected area electron diffraction pattern recorded on the nanowires show monoclinic structure with preferential growth direction of [0 1 0]. The growth mechanism of α-Bi2O3 nanowires was interpreted with a two-step growth model by accounting the formation of facets via Au-catalyzed and the growth of α-Bi2O3 nanowires via Bi-catalyzed process. Photoluminescence spectra reveal intense visible luminescence of the α-Bi2O3 nanowires due to different inter-band transitions between defects (oxygen vacancy, VO), impurity and different valence states of bismuth ions (Bi2+ and Bi3+). The formation mechanism is suggested that Au nanoparticles play a vital role in the growth of pure α-Bi2O3 nanowires.