Published online by Cambridge University Press: 21 February 2011
Thin films of crystalline titania with different grain sizes and porositieswere prepared by dip-coating on Si (100) substrates starting from a sol-gelprocess. Three synthesis procedures were developed and compared, usingacetylacetone (acac, with HCI) and acetic acid (HOAc) as modifying agents ordirectly using hydrochloric acid as catalyst. The structural evolution ofthe films was characterized by Glazing Angle X-ray Diffraction (XRD),Spectroscopic Ellipsometry and Atomic Force Microscopy (AFM). Anatase phasewas observed on all of the films calcined at 440° C. The grain sizes andcrystallinity generally increased with calcination temperature. Thin filmsobtained from acac- and HOAc-modified titanium sols had fine grains (50–80nm) and less porosity (<10%) after calcination at 1000° C. Thin filmsderived from the sol catalyzed directly with acid had the largest grains(90–130 nm), higher crystallinity and greater porosity (17%).