Dissociative diffusion ofFe57inβ-Sn as observed by Mössbauer effect

Abstract

The M\"ossbauer effect of $^{57}\mathrm{Fe}$ atoms in $\ensuremath{\beta}$-Sn was measured over the temperature range 90-462\ifmmode^\circ\else\textdegree\fi{}K with a polycrystalline source specimen. The spectra were decomposed into two major pairs of doublet lines and a minor line. The results were interpreted in terms of a dissociative diffusion mechanism. The lines were assigned to interstitial, substitutional, and clustered $^{57}\mathrm{Fe}$ atoms. The diffusional broadening gave the diffusion coefficient of interstitial Fe atoms along the $c$ axis as ${D}_{i}=1.8(\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\mathrm{exp}[\ensuremath{-}\frac{0.47(\ifmmode\pm\else\textpm\fi{}0.07)}{\mathrm{kT}}]$. The effective solute diffusivity comparable with a tracer diffusion coefficient turned out to be ${D}_{I}=4.8(\ifmmode\pm\else\textpm\fi{}3.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\mathrm{exp}[\ensuremath{-}\frac{0.53(\ifmmode\pm\else\textpm\fi{}0.08)}{\mathrm{kT}}]$.