Self-diffusion in Germanium-rich liquid Germanium-Nickel investigated by quasielastic neutron scattering

Abstract

We report atomic dynamics in liquid Ge98Ni2 measured using quasielastic neutron scattering. Isotopic substitution enabled to separately determine Ge and Ni self-diffusion with high accuracy. The Ge self-diffusion coefficient in liquid Ge98Ni2 is equal within error bars to that in pure liquid Ge. However, the Ni self-diffusion coefficient lies at least 30% below the Ge self-diffusion coefficient. This behaviour differs from previously reported atomic dynamics in Ge-rich GeAu, GeSi, GeIn and GeCe melts, where no separation of the self-diffusion coefficients between the minor component and Ge is observed. The change of the atomic dynamics already at an addition of 2 at% Ni points to electronic and chemical origins in Ge98Ni2. Moreover, the slower self-diffusion of the minor component compared to Ge might be associated with two different local structural environments, as observed in Ge-Ni alloys at higher Ni concentration.