Al2O3-TiO2 thin films on glass substrate by sol-gel technique

In the present research, self-cleaning Al2O3-TiO2 thin films were successfully prepared on glass substrate using a sol-gel technique for photocatalytic applications. We investigated the phase structure, microstructure, adhesion and optical properties of the coatings by using XRD, SEM, scratch tester and UV/Vis spectrophotometer. Four different solutions were prepared by changing AIM molar ratios such as 0, 0.07, 0.18 and 0.73. Glass substrates were coated by solutions of Ti-alkoxide, Al-chloride, glacial acetic acid and isopropanol. The obtained gel films were dried at 300 degrees C for 10min and subsequently heat-treated at 500 degrees C for 5 min in air. The oxide thin films were annealed at 600 degrees C for 60 min in air. TiO2, Ti3O5, TiO, Ti2O, alpha-Al2O3 and AM phases were determined in the coatings. The microstructural observations demonstrated that Al2O3 content improved surface morphology of the films and the thickness of film and surface defects increased in accordance with number of dipping. It was found that the critical load values of the films with 0, 0.07, 0.18 and 0.73 AIM molar ratios were found to be 11, 15, 22 and 28mN, respectively. For the optical property, the absorption band of synthesized powders shifted from the UV region to the visible region according to the increase of the amount of Al dopant. The oxide films were found to be active for photocatalytic decomposition of methylene blue. (c) 2006 Elsevier Inc. All rights reserved.