Diffusion of lead in cadmium

Abstract

The anisotropic diffusion coefficients of $^{210}\mathrm{Pb}$ in single crystals of cadmium have been measured by the tracersectioning method. The results of the measurements are ${D}_{\ensuremath{\parallel}}=(0.060\ifmmode\pm\else\textpm\fi{}0.024)\mathrm{exp}[\ensuremath{-}\frac{(16.46\ifmmode\pm\else\textpm\fi{}0.44 \frac{\mathrm{kcal}}{\mathrm{mole}})}{\mathrm{RT}}]$, ${D}_{\ensuremath{\perp}}=(0.071\ifmmode\pm\else\textpm\fi{}0.02)\mathrm{exp}[\ensuremath{-}\frac{(15.71\ifmmode\pm\else\textpm\fi{}0.19 \frac{\mathrm{kcal}}{\mathrm{mole}})}{\mathrm{RT}}]$, all in ${\mathrm{cm}}^{2}$/sec. This study of the diffusion of a quadrivalent impurity in cadmium supplements an earlier investigation of the diffusion of mono-, di-, and trivalent atoms in the same matrix. The activation energies obtained in this study can be interpreted with LeClaire's screening model. Fair agreement between the experimental results and theoretical calculations are obtained. It indicates that the valence effect is indeed playing a dominant role in diffusion.