Gas-Sensing Potential of Nanocrystalline SNO2 Produced by Different Chemical Reactions and Milling Conditions

摘要

In this work, the mechanochemical processing of undoped nanocrystalline SnO2 powders and the subsequent preparation of thick films were studied. SnCl2 powder was milled with Ca(OH)2 and K2CO3 powder respectively in a ball-mill at room temperature and in an air atmosphere. Heat treatment of milled mixtures at 400 deg. C resulted in the formation of a tetragonal phase. The Fourier-transform infrared spectra (FTIR) and X-ray diffraction patterns (XRD) for the different powders are reported. A significant feature is that during milling in the presence of water a high number of OH groups are formed at the surface. After heat-treatment the OH bonds of adjacent SnO2 grains are probably transformed into Sn-O-Sn bridges. On exposure to H2S gas, the SnO2 film, prepared from anhydrous powder, has higher sensitivity than the SnO2 film, prepared from hydrated powder. It was found that with appropriate selection of milling conditions and chemical reaction, the obtained powder might be successfully applied to a H2S gas sensor.