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

Abstract

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 α-Bi2O3 and tetragonal β-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.

Luminescence centers in α-Bi2O3 ceramics

“…According to the literature [9], photoluminescence of δ-Bi 2 O 3 films exhibits maxima at 2.63, 2.44, and 2.01 eV. It is interesting that our results were qualitatively similar also to the investigation of luminescent nanostructures of Bi 2 O 3 [10]. Various nanostructures of Bi 2 O 3 13-42-nm in diameter and tens of µm in length were formed in a two-phase system with monoclinic α-Bi 2 O 3 and tetragonal β-Bi 2 O 3 .…”

“…Various nanostructures of Bi 2 O 3 13-42-nm in diameter and tens of µm in length were formed in a two-phase system with monoclinic α-Bi 2 O 3 and tetragonal β-Bi 2 O 3 . Their photoluminescence spectra were a broad band with the principal maximum at 2.07-2.10 eV depending on the structure type and with a local maximum near 2.34 eV [10]. This indicates that the spectral luminescent properties are similar regardless of the Bi 2 O 3 crystal structure for various modifications.…”

Laser irradiation-induced α to δ phase transformation in Bi2O3 ceramics and nanowires

“…In particular, a dominant band peaked near 2.41 eV, with well resolved shoulders at 2.82 eV and 2.21 eV, can be clearly appreciated in spectra from the irradiated nanowires. Emission in the (3.1-2.2) eV spectral range has usually been attributed to Bi 3þ intraionic transitions or charge transfer transitions between oxygen ligands and Bi 3þ ions 14,27,28 in aBi 2 O 3 , while luminescence bands in the (2.10-1.87) eV range were commonly assigned to Bi 2þ intraionic transitions. 14,29 Furthermore, laser irradiation gives rise-in PL spectra of ceramics and nanowires-to an intense band centered at 1.67 eV, not observed in samples with the a-Bi 2 O 3 structure.…”

A note on the characterization of bismuth black by Raman microspectroscopy

“…Nonetheless, Raman spectroscopy has been employed in recent studies of bismuth nanoparticles, [10 -12] clusters [13] and thin films [14] where the fundamental Raman modes, [15] E g and A 1g , were monitored to study changes in structural properties such as particle size and crystallinity. Raman spectroscopy also has been used to characterize bismuth oxide powders and single-crystals, [16 -18] and, more recently, bismuth oxide nanostructures [19,20] and thin films. [14] However, all these previous studies employed visible excitation wavelengths, ranging from 488 to 647 nm.…”