Journal of the American Ceramic Society, Vol.93, No.9, 2897-2902, 2010
Sol-Gel Processing of Bi2Ti2O7 and Bi2Ti4O11 Films with Photocatalytic Activity
A new sol-gel synthesis based on chloride compounds as precursors has been used to prepare bismuth titanate (BT) films. The films have been deposited by dip-coating and fired at different temperatures in air; they remain amorphous up to 500 degrees C, and crystallize into the pyrochloric cubic phase Bi2Ti2O7 between 600 degrees and 700 degrees C while at higher temperatures of firing the stable Bi2Ti4O11 monoclinic phase is formed. The films have been characterized by X-ray diffraction analysis at gracing incidence, X-ray photoelectron spectroscopy, ellipsometric spectroscopy, UV-visible absorption, and atomic force microscopy. The photocatalytic properties of the films have been evaluated by exposing a methyl orange solution containing the BT films to UV light. The test has shown that the Bi2Ti2O7 films have a higher activity in comparison with reference anatase titania films.