Structural and functional properties of nanocomposite Au-WO3 coatings

In this study several Au-WO3 nanocomposite coatings were deposited by reactive magnetron co-sputtering and characterized with respect to their chemical composition, structure, microstructure and mechanical and optical properties. The nanocomposites consist of a dual phase system of Au nanoparticles dispersed homogeneously in an amorphous WO3 matrix, with compositions ranging between 0 and 11 at.% Au. To enhance the surface plasmon resonance effect in the coatings, the growth of Au nanoparticles was stimulated by applying a thermal annealing treatment at different temperatures up to 500 °C. The annealing treatments promoted the crystalization of the WO3 matrix. The hardness of the coatings remained close to 4.5 GPa, irrespectively of the Au content and annealing temperature. As a result of the microstructural changes in both the nanoparticles and matrix, surface plasmon resonance effect was successfully enhanced and different colourations were obtained in the coatings.