Mössbauer-effect studies of the lattice dynamics of granular tin

Abstract

The atomic mean-square displacement (MSD) of granular tin was studied by the M\"ossbauer effect. Tin grains with a 45-\AA{} average size embedded in an oxide matrix were produced by evaporating the metal in the presence of ${\mathrm{O}}_{2}$. The lattice parameters and grain-size distribution were measured by electron microscopy. From the temperature variation of the MSD of the granular material, it was found that the $〈{\ensuremath{\omega}}^{\ensuremath{-}2}〉$ moment of the phonon spectrum increases by (8\ifmmode\pm\else\textpm\fi{}3)% with respect to the bulk. These results, combined with data of the hyperfine constants and electron microscopy suggest a quasi-isolated grain whose vibration frequency and electronic structure are barely altered and whose interaction with the surrounding oxide is negligible.