Influence of Nb on mechanical and optical properties of Nb-doped-TiO2 thin films prepared by sol-gel method.

Reference Presenter Authors
(Institution)
Abstract
06-077 Gustavo Henrique Magalhães Gomes Gomes, G.H.(Universidade Federal de Minas Gerais); Jesus, M.A.(Universidade Federal de Minas Gerais); Ferlauto, A.S.(Universidade Federal de Minas Gerais); Viana, M.M.(Universidade Federal de Minas Gerais); Mohallem, N.D.(Universidade Federal de Minas Gerais); TiO2 is a semiconductor that can be used in many applications, such as photocatalysis, energy devices, water disinfection and antimicrobial surfaces. TiO2 can be prepared as bulk, nanoparticles or thin films and its band-gap depends on the particle size and crystalline phase. As thin film, it is very important to understand how the structure and morphology affects the optical and mechanical properties, such as transmittance, band-gap, dielectric function, hardness and Young’s module. In this work, pure TiO2 and 0.5, 1.0 and 3.0% Nb-doped-TiO2 thin films were deposited on glass substrate using the sol-gel route and the dip-coating process. The thin films were produced varying the calcination temperature (200, 300, 400 and 500 °C). UV-Vis diffuse reflectance spectra were used to obtain information about optical band-gap; ellipsometry analysis was used to obtain the Psi & Delta spectra of the samples; Cauchy model was used to characterize the optical properties of the substrate and Tauc-Lorentz model to evaluate thickness, roughness, band-gap and dielectric function of the films. AFM were used to obtain information about the mechanical properties of the thin film. Dielectric functions of thin films showed that Nb-doped-TiO2 is denser than TiO2 with higher real and complex dielectric functions and no significant changes in the band-gap was observed. AFM analysis showed changes in the morphology and texture of the thin films, also the evaluation of the difference of mechanical properties between doped and undoped TiO2 thin films. 
I would like to thank UFMG-Microscopy Center for the structural support and CNPq, CAPES and FAPEMIG for financial support.
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