The Reactive Surface Sites and the H[sub 2]S Sensing Potential for the SnO[sub 2] Produced by a Mechanochemical Milling

powder was milled with and powder respectively in a ball mill at room temperature and in an air atmosphere. Pure was obtained by removal of the or KCl by-product by washing the powder. An initial composition of and was milled to produce the doped phase with Cr on the surface. Heat-treatment results in the formation of a tetragonal phase. The infrared spectra for the different powders and from thick films of these materials are reported. An important finding is that during milling in the presence of water, OH groups are formed at the surface in great numbers. After heat-treatment at 400°C or higher, the OH bonds of adjacent grains are probably transformed into Sn-O-Sn bridges. Washing the material with pure ethanol, instead of water, can result in the reduction of intensity for the band at 1450 cm −1 due to the presence of the bridge bonding Sn-O-Sn. On exposure to and CO gas, the film prepared from anhydrous powder, has higher sensitivity than the film, prepared from hydrated powder. It is shown that the produced by mechanochemical synthesis can be successfully applied to a gas sensor.