Interdiffusion of ⁶Li and ⁷Li in Isotopically Nearly Pure Lithium Metal Melts

A capillary-reservoir technique has been used to investigate the interdiffusion of 6 Li and 7 Li in nearly pure (ca. 94%) 6 Li, as well as in nearly pure 7 Li. At the melting point the ratio of these diffusion coefficients is about 1.30. Extrapolation to tracer concentrations gives good qualitative agreement with the ratio of the viscosities of 7 Li and 6 Li. The interdiffusion coefficient ratio of the melts decreases with rising temperature, also in agreement with viscosity results. Quantum effects are likely to be responsible for the strong dependence on isotope mass.