Synthesis of bismuth oxide nanostructures by an oxidative metal vapour phase deposition technique

The large-area arrays of one-dimensional (1D) nanowires and nanoflowers of bismuth oxide (Bi2O3) were synthesized by the oxidative metal vapour phase deposition technique with controlled flow of oxygen and constant working pressures. Surface morphology analysis showed that the as-synthesized product at 10 Torr consisted of 1D nanowires with diameters about 13-42 nm and lengths up to several tens of micrometres. The other working pressure of 30 Torr accounted for the formation of nanoflowers with a petal-like structure. Elemental analysis confirms the presence of only the elements Bi and O. The crystalline nature of the 1D nanostructure is revealed by high resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) studies. X-ray diffraction (XRD) analysis indicates the formation of a two-phase system with monoclinic alpha-Bi2O3 and tetragonal beta-Bi2O3. Raman signals of the synthesized nanostructures are identified and assigned to various phonon vibration modes of Bi and Bi2O3. The photoluminescence (PL) spectrum shows a visible broadband emission in the wavelength range, 500-800 nm.