Determination of self-diffusion coefficients by quasielastic neutron scattering measurements of levitated Ni droplets

Conventional techniques to measure diffusion coefficients in liquid metals and alloys are hampered by buoyancy-driven convective fluid flow and chemical reactions of the liquids with container material. To overcome these obstacles we combined containerless processing via electromagnetic levitation with quasielastic neutron scattering. This combination allowed us to study the atomic self-motion in liquid nickel within a broad temperature range from $200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ above to more than $200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ below the melting point, in the metastable regime of an undercooled melt. Other than in liquid Sn the temperature dependence of the Ni self-diffusion coefficient is well described with an Arrhenius law.