SAXS- and ASAXS-investigation of TiO2-SiO2 gels

Overview & Synopsis

Gels in the system SiO2-TiO2 were prepared by hydrolytic polycondensation of the corresponding alkoxides by use of acetyl acetone as an additive in order to reduce the rate of hydrolysis of the Ti-alkoxide as well as by use of pre hydrolysis of the slower reacting Si-alkoxide and storage before mixing with the Ti-alkoxide. All investigated gels are characterized by very small particles varying in Guinier radius in the range between 0.8 nm and 1.0 nm. These particles aggregate to form fractal clusters with a fractal dimension of nearly 2.0. Anomalous SAXS at the Ti-K-edge gives information about the behaviour of the TiO2 in the process of gelation. The resonant part of the scattering curve of the samples characterized by a high content of acetyl acetone shows that the TiO2 component is equally distributed in the system and does not take part in the formation of fractal cluster.