Isotope effect in chromium self-diffusion

Abstract

The diffusion of $^{51}\mathrm{Cr}$ in chromium has been measured between 1100 and 1820\ifmmode^\circ\else\textdegree\fi{}C, and the data fit the Arrhenius relation $D=970\mathrm{exp}(\ensuremath{-}\frac{104000}{RT})$ ${\mathrm{cm}}^{2}$${\mathrm{sec}}^{\ensuremath{-}1}$. Isotope-effect measurements, using isotopes $^{48}\mathrm{Cr}$ and $^{51}\mathrm{Cr}$, have been made over the temperature range 1440-1810\ifmmode^\circ\else\textdegree\fi{}C. The isotope effect decreases as the temperature increases in a manner similar to that found for sodium and iron in the same homologous temperature range. The large activation energy for diffusion and the low values of the isotope effect could be predominantly the result of a divacancy mechanism of diffusion over the measured temperature range.