AN ATOMIC-SCALE STUDY OF THE ROLE OF TITANIUM IN TIO2-SIO2 SOL-GEL MATERIALS

Neutron diffraction data is used to reveal details of the effect of ad ding titania to a silica-based sol-gel, including a first direct obser vation of the Ti-O correlation, At low Ti contents the data are consis tent with the 4-fold oxygen coordination derived from NMR. Even at the se concentrations the silica network is shown to have been affected si gnificantly, with bond-length distributions being narrowed, and with a high level of network-OH indicating a qualitative change in the mesos copic structure associated with interfacial surfaces, Data on a phase separated sample supports the conclusion that the network-OH is associ ated with the phase separation process.