EXAFS and XANES Studies of Silica-Titania Sol-Gel Films

A series of SiO₂-TiO₂ sol-gel films with and without heat treatment were analyzed by EXAFS and XANES spectroscopies. Both techniques indicate that essentially all Ti⁴⁺ ions remain four-fold coordinated, with a Ti–O bond distance between 1.82–1.85 Å. In the glassy films produced by heat treatment at 900° C, a gradual phase separation may occur at the nanoscale, as the TiO₂ concentration of the films increases.