H. Weis, D. Holland-Moritz, F. Kargl, F. Yang, T. Unruh, T. C. Hansen, J. Bednarčik, A. Meyer

We studied structure and dynamics in liquid Ge and ${\text{Si}}_{20}{\text{Ge}}_{80}$. Quasielastic neutron scattering (QNS) was employed to accurately determine the Ge self-diffusion coefficient. Static structure factors were measured using neutron and x-ray diffraction. Containerless processing via electromagnetic levitation (EML) enabled to obtain structure factors over a broad temperature range from the metastable regime of the undercooled melt to several hundred Kelvin above the melting point. Moreover, isotopic substitution and combination with x-ray diffraction allowed to determine the partial structure factors ${S}_{\mathrm{NN}}\left(q\right),{S}_{\mathrm{NC}}\left(q\right),{S}_{\mathrm{GeGe}}\left(q\right)$, and ${S}_{\mathrm{GeSi}}\left(q\right)$ for liquid ${\text{Si}}_{20}{\text{Ge}}_{80}$. The topological structures of liquid Ge and ${\text{Si}}_{20}{\text{Ge}}_{80}$ are very similar. In addition, the Ge self-diffusion coefficients in liquid Ge and ${\text{Si}}_{20}{\text{Ge}}_{80}$ are equal within error limits.