⁶Li and⁷Li diffusion coefficients in solid lithium measured by the NMR pulsed field gradient technique

Abstract

The authors report measurements of the 6Li and 7Li diffusion coefficient DNMR in both natural Li and enriched 6Li by the NMR pulsed magnetic field gradient techniques. Between 350 K and the melting point (454 K) DNMR obeys an Arrhenius law with an average activation energy of 0.561+or-0.002 eV. The isotope effect can be explained in terms of classical statistics (mass dependence of the attempt frequency). By combining their DNMR data with the uncorrelated self-diffusion coefficient DSD determined by NMR spin-lattice relaxation measurements they obtain the effective correlation factor which decreases with rising temperature.