The influence of annealing treatments on the properties of Ag:TiO2 nanocomposite films prepared by magnetron sputtering

The present paper reports on the preparation and characterization of DC reactive magnetron sputtered Ag:TiO2 nanocomposite coatings, with a silver content of about 8 at.% (average estimation). The as-deposited samples were subjected to annealing, in a protective atmosphere, at temperatures ranging from 200 to 800 °C. Morphology, structure, hardness and friction behaviour were characterised after each heat treatment. The cross-sections of the films were studied by transmission electron microscopy (TEM). X-ray diffraction (XRD) was used to determine the thin-film structure and crystallinity as a function of annealing temperature. XRD analysis confirmed the presence of silver in all the samples and the crystallization of the TiO2 matrix for the samples annealed at temperatures above 300 °C. These structural changes were also followed by significant morphological variations, which resulted in the change of the mechanical properties of the films (hardness and Youngʹs modulus) as well as of their tribological behaviour.