PROCESSING AND CHARACTERIZATION OF POROUS TIO2 COATINGS

Titania coatings were prepared by spin coating anhydrous titanium etho xide solutions onto Si substrates. During deposition, Ti ethoxide in t he solution layer reacted with atmospheric moisture to form precipitat ed particles. The resulting microstructures were composed of a network of particles and particle clusters. The induction time for precipitat ion, the particle diameter, and the size and packing of particle clust ers were influenced by the Ti concentration in the sol and the spinnin g rate used for deposition. Individual particle sizes ranged from appr oximately 150 to 250 nm. Smaller particles and more compact particle c lusters were characteristic of coatings prepared from solutions with l ower Ti concentrations and those prepared using faster spinning rates. As-deposited coatings were amorphous and crystallized into the anatas e phase at approximately 400-degrees-C. Transformation to the rutile p hase began at approximately 850-degrees-C, and the transformation rate was influenced by the microstructure.