Textural properties of nanocrystalline tin oxide obtained by spray pyrolysis

This work analyses the textural evolution, characterised by N₂ adsorption and Hg porosimetry, of tin oxide (SnO₂) obtained by spray pyrolysis (300–900 °C) and subjected to thermal treatments at 600 and 800 °C. The so-obtained materials have also been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS); resistance measurements were made on annealed pellets of these materials. After the thermal treatment, samples obtained at lower pyrolysis temperatures (300–500 °C) undergo a complete collapse of their original structure: the initial hollow spheres transform into polyhedral crystals of the same order of magnitude. On the other hand, those obtained at higher temperatures (700–900 °C) maintain the original morphology, although the initial smooth surface becomes wrinkled due to the increase of the crystals size as a consequence of the sintering process.