Faceting characterization of tin dioxide nanocrystals deposited by spray pyrolysis from stannic chloride water solution

Tin dioxide (SnO2) thin films grown by spray pyrolysis on Si substrates were studied. The evolution of the crystallographic orientation of these films (35-300 nm) with variation of the pyrolysis temperature (350-535 °C) is reported. Samples were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and High Resolution Transmission Electron Microscopy (HRTEM). Via digital image processing of the HRTEM micrographs, some crystallographic models of SnO2 nanocrystals deposited at different pyrolysis temperatures are proposed. These models were tested by computer image simulation and compared with the experimental images. It was found that, in addition to the most stable plane (110), the external facets of SnO2 nanocrystals can be formed by crystallographic planes with other structural and electronic configuration: planes (111), (200), (101), (011), (-1-12), and (210).