Effects of 60Co γ-radiation on the structural, morphological, optical, tribological and mechanical properties of SnO2 sprayed thin films

Tin oxide (SnO2) thin films have been used, in the last decades, in a variety of devices and applications exposed to high-energy radiation that affects their physical properties. In this manuscript, the influence of 60Co & gamma;-radiation (with doses of 30, 45, 60, 75 and 90 kGy) on the characteristics of SnO2 thin films is studied thoroughly. The produced films were deposited on ordinary glass, preheated at 450 degrees C, using the spray pyrolysis method. The effects of the different doses of gamma-ray on the properties of SnO2 thin films were characterized by X-ray diffraction, scanning electron microscopy, UV-vis spectroscopy and mechanical tests. The experimental results show that irradiation led to considerable modifications in the structural, morphological, optical, tribological and mechanical characteristics of the studied films. These changes occurred regularly when radiation doses were below 60 kGy and randomly when doses were above that value. XRD results reveal that by increasing the irradiation dose up to 60 kGy, crystallite size increased from 46.22 to 56.39 nm. However, dislocation density and microstrain showed an opposite trend to crystallite size with absorbed doses. This behavior can be explained by the crystallite rearrangement due to the increase of the temperature under the effect of irradiation. The & gamma;-irradiation led to a decrease in the optical gap energy from 4.0 to 3.9 eV as the & gamma;-dose increased from 0 to 60 kGy because of the modification of the structural defect. The & gamma;-irradiation affected significantly the mechanical properties of the deposited SnO2 thin films. It was observed that the parameters of hardness, wear resistance and substrate adhesion decreased while the friction coefficient increased (from 0.07 to 0.09) with increasing the & gamma;-radiation dose. In addition, the surface of SnO2 thin films became smoother with the increase of the irradiation dose. However, the surface was not damaged with the change of the film morphology. Despite the different changes undergone by SnO2 films when irradiated with gamma rays, they are still efficiently employed in a variety of applications.