Properties And Preparation Of Nanostructured SnO₂

SnO₂ is a kind of wide-band semiconductor material, the band gap of which is 3.67 eV at room temperature. It has good chemical stability and optical anisotropy. SnO₂ nanomaterials has advantages such as small particles and high specific surface area, thus it can be used in air sensitivitied apparatus, Li ion batteries, transparent conductive glasses and solar batteries. In this thesis, The SnO₂ nanoparticles have been prepared by sol-gel method, and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The properties are measured by UV-Vis-NIR spectroscopy, photoluminescence (PL) spectroscopy and surface photovoltage spectroscopy (SPS).1. From the result of XRD, SEM and TEM, it has been found that the particle size of SnO₂ is about 50 nm, and the phase structure is pure rutile.2. The band gap energies of SnO₂ nanoparticles are calculated to be about 3.91-3.98 eV from the diffuse reflectance spectrum (DRS). The Urbach energies are found to be increasing from 0.219 to 0.46 eV with the decrease of annealing temperature.3. From the PL spectra, it can be clearly seen that two intense emission bands centered at 413 nm and 434 nm in SnO₂ nanocrystalline with the excitation wavelength of 320 nm. Some certain localized levels may exist within the forbidden gap as the corresponding emission energies are smaller than the optical band gap.4. The SPS of SnO₂ nanocrystallines exhibits a strong photoelectric response around 340 nm.