Using a first-principles method, an investigation was made of the dissolution and diffusion properties of oxygen in tungsten. Single O atoms preferred to occupy the tetrahedral interstitial site (TIS). Two interstitial O atoms were attractive and tend to be paired up at two neighbouring TIS with a distance of 0.228nm and a large binding energy of 1.60 eV, which indicates a strong tendency of O clustering in W. O was preferred to diffuse between the most nearest neighbouring TIS with a diffusion barrier of 0.17 eV. By the estimation of pre-exponential factor according to an empirical theory, the diffusion coefficient as a function of temperature was determined, which was 1.50 x 10−9 m2/s at a typical temperature of 500K. The results provide a good reference to understand the behavior of O in intrinsic W.

First-Principles Investigation on Dissolution and Diffusion of Oxygen in Tungsten . A.Alkhamees, Y.L.Liu, H.B.Zhou, S.Jin, Y.Zhang, G.H.Lu: Journal of Nuclear Materials, 2009, 393[3], 508-12