The effect of Fe atoms on the adsorption of a W atom on W(100) surface

TL;DR

This study uses first-principles calculations to show how Fe atoms on W(100) surfaces influence W atom adsorption, facilitating desorption and diffusion, and explaining activated tungsten sintering.

Contribution

It reveals the atomic-level mechanism by which Fe atoms enhance W atom desorption and diffusion on W(100), advancing understanding of tungsten sintering processes.

Findings

W atoms adsorb on Fe monolayer before replacing Fe atoms

Presence of Fe lowers W adsorption energy by 2.4 eV

Fe atoms facilitate W atom diffusion and desorption

Abstract

We report a first-principles calculation that models the effect of iron (Fe) atoms on the adsorption of a tungsten (W) atom on W(100) surfaces. The adsorption of a W atom on a clean W(100) surface is compared with that of a W atom on a W(100) surface covered with a monolayer of Fe atoms. The total energy of the system is computed as the function of the height of the W adatom. Our result shows that the W atom first adsorbs on top of the Fe monolayer. Then the W atom can replace one of the Fe atoms through a path with a moderate energy barrier and reduce its energy further. This intermediate site makes the adsorption (and desorption) of W atoms a two-step process in the presence of Fe atoms and lowers the overall adsorption energy by nearly 2.4 eV. The Fe atoms also provide a surface for W atoms to adsorb facilitating the diffusion of W atoms. The combination of these two effects result in a much more efficient desorption and diffusion of W atoms in the presence of Fe atoms. Our result provides a fundamental mechanism that can explain the activated sintering of tungsten by Fe atoms.