Nh. March et Di. Pushkarov, MASS-TRANSPORT BY CROWDIONS - A SIMPLE-MODEL APPROPRIATE TO BODY-CENTERED-CUBIC NA AND K, Journal of physics and chemistry of solids, 57(1), 1996, pp. 139-140
The relevance of self-interstitials to low-temperature diffusion in bo
dy-centred-cubic Na and K metals is briefly reviewed. Previous studies
have been based largely on numerical computations, with an assumed in
ter-ionic force field. Therefore, a simple model is proposed here in w
hich the formation and motion energies of crowdions, E(f) and E(m) res
pectively, are related to a characteristic energy Ms(2) where M is the
atomic mass and s an appropriate sound velocity, and to N, the number
of atoms involved in the crowdion motion. This model leads to the con
clusion that E(f) much greater than E(m). Isotope effects in Na metal
find a natural explanation in such a crowdion model.