Calculation of the formation entropy and diffusivity constants for the vacancy in Mg

Abstract

By assuming a pair interatomic potential which reproduces some Mg properties, we calculate the formation entropy for a vacancy in an hep lattice. A value of that entropy between 1.5 and 2k is obtained at variance with previous experimental findings which favor a very small value. By a quasistatic computer-simulation approach the migration energies for the yacancy on different lattice directions are also calculated; two different potentials are used for this calculation. Subsequently migration entropies and diffusivities are evaluated. A good agreement with reported experimental values is obtained. Diffusion in hep structures is space anisotropic, and the relative influence on this anisotropy of the migration energy with respect to the entropy is discussed.