Preparation and structural characterization of nanocrystalline SnO2 powders

Nanocrystalline SnO2 powders have been prepared by solid–liquid reaction and solid-state thermal oxidizing techniques. The microstructures and phase compositions of the product were characterized by thermogravimetry analysis, X-ray diffraction, and the Raman spectrum. It is shown that at least two phases, SnO2 and SnOx, coexist at 450 °C. However, only the tetragonal rutile structure SnO2 phase is detected after the Sn powders were annealed at 550 °C. The Raman peaks of the nanocrystalline SnO2 powders reveal remarkable red shift and broadening, which could be attributed to the phonon confinement effect, oxygen vacancies, and the stress effect.