Quench-ring assisted flame synthesis of SiO2-TiO2 nanostructured composite.

A flame aerosol reactor (FLAR) was used to synthesize SiO2-based nanocomposite materials of SiO2-TiO2 in different precursor molar ratios and quench ring positions. Processing conditions were determined that resulted in formation of different crystal phases at different precursor concentration molar ratios. The results showed that the addition of SiO2 inhibited TiO2 phase transformation from anatase to rutile. The different morphology of SiO2-TiO2 nanocomposite was primarily the result of changing the quench ring position. Quenching can stop the growth kinetics, and this was obtained by locating the quench ring at different positions in the particle formation process. At a lower position, a binary mixture of SiO2-TiO2 was obtained in a core-shell structure. The difference in residence time for sintering and coalescence yielded different morphologies of SiO2-TiO2 nanocomposites. The results from FTIR confirmed Si-O-Ti bonding for all samples. The samples of SiO2-TiO2 exhibited better suspension in liquid than pure TiO2 as confirmed by zeta potential measurements.