Zohreh Nafari Qaleh

By Reza Sabet Dariani and Zohreh Nafari Qaleh

TiO2 nanowires (NWs) have been fabricated by thermal evaporation method, using the vapor–liquid–solid (VLS) growth method and Au thin layer as a catalyst which were coated on titanium/quartz substrate. Optical and microstructure properties of TiO2 NWs have been reviewed under different argon carrier gas flows. The gas flow was varied from 60 to 170 sccm. The X-ray diffraction patterns showed that TiO2 NWs formed in rutile phase and their preferred orientation was in (110). The field emission scanning electron microscope figures indicated that with increasing gas flow, nanowires became thinner and longer. The absorbance curve of TiO2 nanowires has been drawn by using spectrophotometer and their band gap was measured. Our results showed that the band gap has been enhanced in comparison with bulk one due to the quantum confinement. Also, the band gap enhanced from 3.35 to 3.45 eV by increasing the argon flow, since the wires became thinner and longer. The Williamson–Hall mechanism was applied as the vital tools for characterization of crystallite size and microstrain. Also, microstructure properties have been studied by X-ray diffraction analysis such as; dislocation density and texture coefficient. The crystallinity of TiO2 NWs has been made better by enhancing Ar flow due to increasing of VLS growth method.

Part of the book: Nanoparticles Technology