Microstructure and electrical conductivity of Au–MgF2 nanoparticle cermet films

Au–MgF2 nanoparticle cermet films with Au volume fraction of 6–50% were prepared by radio-frequency magnetron co-sputtering and analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and temperature-varying four-wire technique. Microstructure analysis shows that the films are composed of mainly amorphous MgF2 matrix with embedded fcc Au nanoparticles with a mean size of 9.8–21.4 nm. The electrical properties of the films from 54 to 300 K were measured. The results show that the electrical percolation threshold occurs between Au 40 vol.% and 50%, and around the percolation threshold the electrical conductivity of the films changes by four orders.