XPS AND XAES STUDY OF TIO2-SIO2 MIXED-OXIDE SYSTEM

An XPS and XAES (X-ray exited Auger electron spectroscopy) investigation was carried out to elucidate the structure of TiO2-SiO2 mixed oxide systems in the broad range of the component concentrations (3 wt % less-than-or-equal-to TiO2 greater-than-or-equal-to 97 wt %). It is found that a homogeneous TiO2-SiO2 solid solution exists at low TiO2 concentrations (TiO2 less-than-or-equal-to 10 wt %). At least two phases (silica-rich content and titania-rich content) coexist in the intermediate TiO2 concentration range. At low SiO2 concentrations (TiO2 greater-than-or-equal-to 85%), silicon forms titanium silicate coating TiO2 particles. Simple calculation of the Si Auger parameter allows prediction of the contraction of the Si-O distance, as compared to the Ti-O distance, upon substitution of Ti to Si.