Behavior of Water and Oxygen Molecules on the Surface of Tin Dioxide Films

Polycrystalline films of compositions SnO₂, SnO_1.93F_0.07, 0.93SnO₂ · 0.07Sb₂O₃, and 0.97SnO₂ · 0.03CuO, which are of interest for use in gas-sensitive sensors, are prepared by the hydropyrolytic method from metal chlorides on a 22-XC ceramic substrate. The films prepared are studied using mass spectrometry, differential thermal analysis (DTA), and thermogravimetric analysis (TGA) at different temperatures. The results of mass spectrometric investigations demonstrate that, except for water (18 amu), no compounds in the mass range 10–70 amu are desorbed from all the films. The differential thermal and thermogravimetric analyses have revealed that desorption of water molecules from the film surface occurs in the temperature range 50–125°C and the oxidation processes associated with the oxygen chemisorption proceed beginning from a temperature of 125°C.