THE EFFECT OF FE ATOMS ON THE ADSORPTION OF A W ATOM ON W(100) SURFACE

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 to 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 an energy barrier of 0.99 eV 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. This effect results in a more efficient adsorption and desorption 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. (C) 2008 American Institute of Physics.