Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...

JUNE 26 MONDAY MORNING
RIVA-TF-MoM-OR.2 STRAIN ANALYSIS OF PHOTOCATALYTIC TiO 2 THIN
FILMS ON POLYMER SUBSTRATES. C.J. Tavares 1 , S.M. Marques 1 , V. Teixeira 1 , J.O. Carneiro
1 , A.J. Fernandes 2 , E. Alves 3 , A.R. Ramos 3 . 1 Departamento de Física, Universidade do Minho,
4800-058 Guimarães, Portugal. 2 Departamento de Física, Universidade de Aveiro, 3810-193 Aveiro,
Portugal.
3 Instituto Tecnológico e Nuclear, EN 10, 2686-953 Sacavém, Portugal.
ctavares@fisica.uminho.pt
Titanium dioxide (titania) is a well known photocatalyst used in the semiconductor industry due its
efficiency in dissociating pollutant organic compounds. Enhancing the photocatalytic efficiency of
this material has become a major concern for the authors, bearing in mind industrial applications for
general purpose plastics. On an industrial environment, handling of these films often may cause degradation
of the coating, hence the vital importance of also enhancing the mechanical properties. TiO 2
thin films have been deposited by unbalanced reactive magnetron sputtering from a high purity Ti
target in an Ar/O 2 atmosphere, at room temperature, on polymer sheets. X-ray diffraction experiments
revealed for a wide range of deposition parameters that the as-deposited titania thin films are
amorphous. The photocatalytic behaviour of the titania coatings was determined by combined ultraviolet
irradiation and absorption measurements. The observed photo-decomposition of the aqueous
solution (organic pollutant) was measured in the UV/Vis spectrum by the decrease of the maximum
absorbance with irradiation time. Analysis of the absorption data allowed us to obtain the decrease in
concentration as a function of time to be observed. In order to assess the mechanical behaviour of the
as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile
testing machine. As the system is stretched, cracks transverse to the loading direction developed in
the film. The number of cracks increased as the applied strain increased, and the relation between the
measured crack density and the applied strain has been used to characterize the film strength and relate
it with the film photocatalytic efficiency.
21