Stability and diffusion properties of self-interstitial atoms in tungsten: a first-principles investigation

Employing a first-principles method based on the density function theory, we systematically investigate the structures, stability and diffusion of self-interstitial atoms (SIAs) in tungsten (W). TheaEuro111aEuro parts per thousand dumbbell is shown to be the most stable SIA defect configuration with the formation energy of similar to 9.43 eV. The on-site rotation modes can be described by a quite soft floating mechanism and a down-hill drift diffusion process from aEuro110aEuro parts per thousand dumbbell to aEuro111aEuro parts per thousand dumbbell and from aEuro001aEuro parts per thousand dumbbell to aEuroA(1)10aEuro parts per thousand dumbbell, respectively. Among different SIA configurations jumping to near neighboring site, the aEuro111aEuro parts per thousand dumbbell is more preferable to migrate directly to first-nearest-neighboring site with a much lower energy barrier of 0.004 eV. These results provide a useful reference for W as a candidate plasma facing material in fusion Tokamak.