Equilibrium concentration of hydrogen at tungsten surface

Abstract In this work, numerical calculations have been employed to investigate the adsorption equilibrium state of hydrogen (H) atoms on tungsten (W) surface. The surface energy and relevant surface atomic density of different W surfaces are obtained through the empirical-potential model. The calculations show that the higher surface atomic densities correspond to the more stable surfaces, of which the most stable surface is the W (110) surface. The H adsorption energies are systematically analyzed by density functional theory. The equilibrium concentration dependence for adsorption upon H coverage, a temperature range from 300 K to 1100 K, and a pressure range from 10−6 Pa to 106 Pa is examined by employing a Monte Carlo model. Our results suggest that most of H atoms desorb from 700 K to 1100 K when the pressure region varies from 10−6 Pa to 102 Pa. The monolayer-adsorbed H density is estimated from ∼1.39 × 1018 m−2 to ∼1.40 × 1019 m−2 at the equilibrium state.