Self-diffusion of 3d transition metals in liquid silicon alloys

Abstract

Self-diffusion coefficients of titanium and cobalt in a silicon melt with 10 at.% metal content were measured in a temperature range between 180 K above and below the liquidus temperature, respectively, with quasielastic neutron scattering. The chemical reactive melts were processed container-less by electromagnetic levitation. Whereas, in crystalline silicon self diffusion coefficients of Ti and Co impurities differ by more than 3 orders of magnitude close to the melting point, in the liquid state values of self-diffusion coefficients of Ti and Co, are equal within error bars and are of the order of 10-8 m2/s. This is in line with a liquid-like, collective transport mechanism that is dominated by the mobility of the surrounding Si atoms.