Comparison of the Isotope Effect for Diffusion of Sodium and Silver in Lithium

Abstract

Separate measurements were made at 150 °C of the simultaneous diffusion of sodium isotopes (${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$) and silver isotopes (${}_{}{}^{105}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{110m}{}_{}{}^{}\mathrm{Ag}$) in lithium. The strength of the isotope effect $f\Delta K$ for sodium is 0.19 ± 0.01 and for silver 0.26 ± 0.01. These values do not correlate well with recent calculations of $\Delta K$ determined for impurity diffusion on the basis of the dynamical theory of diffusion. Measurement of the diffusion of silver in lithium is 45% greater than earlier data, and a possible explanation for this discrepancy is given.