Absolute values of the diffusivities of 6Li in isotopically enriched 6Li melts and of 7Li in natural liquid Li were measured, by using the pulsed field gradient nuclear magnetic resonance technique, at temperatures of between 454 and 580K. The sample sizes and geometries did not require any corrections for systematic errors. It was found that the diffusivities of 6Li and 7Li in 6Li/7Li isotopic alloys decreased significantly with increasing 7Li concentration. This result was thought to be of general significance for self-diffusion in liquid metals, and was clear evidence for the collective nature of self-diffusion in liquid metals. The melting-point ratio (1.25) of the self-diffusivities of 6Li and 7Li (table 94) was significantly greater than the square root (1.08) of the inverse mass ratio. This result was incompatible with classical theories, but agreed with quantum mechanical calculations.

A.Feinauer, G.Majer, A.Seeger: Journal of Physics - Condensed Matter, 1994, 6[26], L355-60

Table 94

Diffusivities of Isotopes in Liquid Li at 454K