Band-gap energy estimation from diffuse reflectance measurements on sol–gel and commercial TiO2: a comparative study

• Published in: Journal of sol-gel science and technology 2012-01, Vol.61 (1), p.1-7
• Main Authors: LOPEZ, Rosendo, GOMEZ, Ricardo
• Format: Article
• Language: English
• Subjects: Absorption spectra; Ceramics; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Comparative studies; Composites; Energy gap; Exact sciences and technology; General and physical chemistry; Glass; Graphical representations; Inorganic Chemistry; Materials Science; Mathematical analysis; Nanocomposites; Nanostructure; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Reflectance; Reflectivity; Representations; Semiconductors; Sol-gel processes; Titanium dioxide
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-011-2582-9

A comparison of the band gap energy estimated from UV–vis reflectance spectra of TiO 2 powders prepared by sol–gel route versus commercial TiO 2 powders, nanopowder, bulkpowder and P25 is reported. The experimental results obtained from the optical absorption spectra were reported for all the TiO 2 samples. Graphic representations were used to calculate E g : absorbance versus λ; F(R) versus E; (F(R) hν ) n versus E, with n = ½ for an indirect allowed transition and n = 2 for a direct allowed transition. From the results, it could be seen that E g strongly varied according to the equation used for the graphic representation. Differences in E g up to 0.5 eV for the same semiconductor depending on the transition chosen were observed. Accurate E g estimation in the four semiconductors studied was obtained by using the general equation α ( hν ) ≈ B ( hν − E g ) n (where α ~ F(R)) and indirect allowed transition.