XPS STUDIES ON THE SURFACE THERMAL MODIFICATIONS OF TIN OXIDES

The authors have studied surface decompositions induced by high-temperature treatments (up to 825 K) at the surface of SnO2 oxide and SnO oxide, the latter being chosen for the purposes of comparison. XPS spectroscopy was used to monitor such modifications. They find that Sn0 forms at the surface when SnO2 and SnO are annealed to 825 K, and non-stoichiometric tin oxide species become apparent in the sub-surface region of the former. Insurgence of Sn metal at the surface of thermally treated tin oxides could be related to the results of recent work by J.W. Erickson and S. Semancik, who reported a significant increase of surface electrical conductivity in SnO2 annealed to 800 K, and higher temperatures.