Influence of the Acidity of the Titania Sol on the Structural and Chemical Properties of Sol-Gel Derived TiO2-SiO2 (30/70) Films
Series of TiO2-SiO2 films with a silica content of 70 mol% were prepared on glass slides by dip-coating method. The mixed sols were prepared via prehydrolyzing of the titania sol in different acidity. The surface chemistry was analyzed by XPS and the topography by AFM. Dissolution of silica was performed in TRIS buffer and the stability of the coatings was tested in simulated body fluid (SBF). The coatings remained crack-free after the TRIS and SBF tests. The formed nanostructure was practically same in all surfaces. The dissolution of silica was slightly increased with the increased acidity of the titania sol. Furthermore, the binding energies (BEs) of the Si(2p) and Ti(2p3/2) peaks obtained from XPS were both shifted upward with increased acidity of the sol. The sol-gel titania-silica materials made with prehydrolyzed titania formed heterogeneous structure where the TiO2 and SiO2 particles were partly interconnected and covered with soluble silica.
Marcelo Prado and Cecília Zavaglia
V. Ääritalo et al., "Influence of the Acidity of the Titania Sol on the Structural and Chemical Properties of Sol-Gel Derived TiO2-SiO2 (30/70) Films", Key Engineering Materials, Vols. 396-398, pp. 725-728, 2009