Determination of the effective dielectric function of silver powders produced by inert gas evaporation

Silver powder samples were prepared by evaporation of silver in an inert gas atmosphere. They were investigated by dc-conductivity-, reflectance- and photoacoustic (PAS) measurements. Model spectra based on the Bergman ansatz for the effective dielectric function ε_eff, the effective thermal and electrical conductivities λ_eff, and σ_eff, were fitted to the experiments. Good agreement has been found assuming a spongily packed, only weakly percolating topology and an increased damping of the free carriers in the small particles (classical size effect).