A first-principles study of self-diffusion and dilute solute diffusion of Au in FCC Ag

Abstract

Diffusion is of great interest to the materials science and engineering community, and computational techniques to calculate diffusion coefficients in a variety of systems provide useful data to the community. Here, the quasi-harmonic Debye model is combined with the PBEsol exchange correlation functional to create an efficient and reliable method for calculating self- and dilute solute diffusion properties in a Ag FCC host lattice. The nudged elastic band method is used for accurately calculating the properties of the transition state as an atom moves into an adjacent vacant lattice site. Comprehensive thermodynamic properties and all factors entering into vacancy mediated diffusion are calculated explicitly as a function of temperature for self-diffusion in a Ag lattice and for the solute diffusion of Au in a Ag host lattice. The calculated results for both systems are compared to known experimental data. For self-diffusion in Ag, the agreement with vacancy concentration, self-diffusion coefficients, and thermodynamic properties validate the methodology for use with solute diffusion in a host Ag lattice. The computational technique is combined with the 5-frequency model for dilute solute diffusion for robust calculation of dilute solute diffusion properties. Au diffusion in Ag is shown to be uncorrelated, and slower than self-diffusion in Ag.