Debye‐Waller Factor for a Vacancy‐Trapped Mössbauer Impurity in Metallic Solid Solutions

Abstract

AbstractThe effect of vacancy trapping of 57Fe atoms present as a dilute impurity in solid solution of aluminium, on the Debye‐Waller factor is evaluated theoretically in the harmonic approximation in the high temperature limit with the help of the double‐time Green function technique. The change in the recoil‐free fraction for the impurity atoms in the presence of nearby vacancies is estimated by using the force constants obtained from the usual Debye relation. A significant change in the Debye‐Waller factor is found with the rise in temperature indicating the effect of temperature on the amount of trapping of point defects by the impurity atoms. The contributions due to the substitutional impurity alone and that in presence of a vacancy adjacent to it are evaluated for a simple cubic crystal with nearest‐neighbour central‐force interactions and are discussed for the zero phonon process.