ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 59, (2) 96 - 102 (2015)

Plško Alfonz 1, Faturíková Katarina 2, Pagáčová Jana 3, Liška Marek 4
1 Alexander Dubček University of Trenčín, Študentská 2, Trenčín SK-911 50, Slovakia
2 Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravská cesta 9, Bratislava SK-845 36, Slovakia
3 Faculty of Industrial Technologies, Alexander Dubček University of Trenčín,I. Krasku 491/34, Púchov SK-020 01, Slovakia
4 Vitrum Laugaricio - Joint Glass Center of the Institute of Inorganic Chemistry, Slovak Academy of Sciences

Keywords: Sol-gel, Films, Physisorption of water, Impedance spectroscopy

The influence of film composition and surface roughness on process of physisorption of water on SiO2-TiO2-Al2O3 films prepared by sol-gel method was studied by impedance spectroscopy. The composition of prepared films, expressed by SiO2:TiO2:Al2O3 ratio, was in the range of following molar ratio: 0:0.95:0.05; 0.32:0.63:0.05; 0.475:0.475:0.05; 0.63:0.32:0.05; 0.95:0:0.05. Complex impedance spectra of thin film sensor for various relative humidities were measured in the range of 0.13 - 97.7 % and the frequency range was 1 kHz to 1 MHz. Measured dependences of complex impedance on frequency were processed by complex nonlinear least squares method. Serial connection with different counts of -(R/C)-, -(R/CPE)- and -R- equivalent circuits was used to analyse obtained spectra. The equivalent circuits were associated with physisorption of water, space charge polarization regions, and bulk or surface conductivity of the films. The dependencies presence of the relaxation processes on the value of relative humidity is used to analyse the process of water physisorption and determine composition influence, too.

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