Abstract

The eight-membered titanium containing siloxane rings (TiX₂)₂O₄(SiBu^t₂)₂ (X = Cl 1, Br 2 or I 3) are efficient single-source precursors to homogeneous titania–silica material. The ceramic conversions which occur pyrolytically at about 550 °C give a mixture of TiO₂–SiO₂ materials. Differential thermal and thermogravimetric analysis, X-ray diffraction, vibrational spectroscopy as well as scanning electron microscopy were used to characterise the materials. It was found that the nature of the halogen atoms play a crucial role in the thermal transformation. Thus, after thermal treatment, silica mixed with anatase is obtained from 1 and 3, whereas silica mixed with rutile is obtained from the brominated precursor 2. The thermal evolution of 1 studied by using Raman and infrared spectroscopies confirms the inhibiting effect of SiO₂ on the anatase–rutile phase transformation. The molecular route to oxide materials described could represent an alternative to the sol–gel process and may offer certain advantages.