Local order and dynamic properties in liquid Au-Ge eutectic alloys byab initiomolecular dynamics

We report the results of first-principles molecular dynamics simulations for liquid and undercooled eutectic Au₇₂Ge₂₈ alloys at various temperatures. In comparison with the parent Au₈₁Si₁₉ liquid, we find a much less pronounced chemical short-range order in Au₇₂Ge₂₈, mainly due to the increasing influence of Ge-Ge nearest neighbor packing. In addition, a structural analysis using three-dimensional pair-analysis techniques evidences an icosahedral short-range order and its evolution with temperature, closer to that of pure Au than to that of Au₈₁Si₁₉. We use such differences to understand the dynamic properties of both systems and to discuss disparities in other properties of Au₇₂Ge₂₈ and Au₈₁Si₁₉ alloys.