In terms of first-principles investigation of H-tungsten (W) interaction,we reveal a generic optimal electron density mechanism for H on W(110) surface and at a vacancy in W.Both the surface and vacancy internal surfa...In terms of first-principles investigation of H-tungsten (W) interaction,we reveal a generic optimal electron density mechanism for H on W(110) surface and at a vacancy in W.Both the surface and vacancy internal surface can provide a quantitative optimal electron density of~0.10electron/(A)3 for H binding to make H stability.We believe that such a mechanism is also applicable to other surfaces such as W( 100) surface because of the (100) surface also providing an optimal electron density for H binding,and further likely actions on other metals.展开更多
The diffusion behaviours of hydrogen （H）, deuterium （D）, and tritium （T） from W（110） surface into bulk and in bulk W are investigated using first-principles calculations combined with simplified models. The di...The diffusion behaviours of hydrogen （H）, deuterium （D）, and tritium （T） from W（110） surface into bulk and in bulk W are investigated using first-principles calculations combined with simplified models. The diffusion energy barrier is shown to be 1.87 eV from W（110） surface to the subsurface, along with a much reduced barrier of 0.06 eV for the reverse diffusion process. After H enters into the bulk, its diffusion energy barrier with quantum correction is 0.19 eV. In terms of the diffusion theory presented by Wert and Zener, the diffusion pre-exponential factor of H is calculated to be 1.57×10-7 m2.s-1, and it is quantitatively in agreement with the experimental value of 4.1×10-7 m2.s-1. Subsequently, according to mass dependence （√1/m） of H isotope effect, the diffusion pre-exponential factors of D and T are estimated to be 1.11×10-7 m2.s-1 and 0.91×10-7 m2.s-1, respectively.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 51101135the National Fusion Project of China for ITER under Grant No 2009GB106003.
文摘In terms of first-principles investigation of H-tungsten (W) interaction,we reveal a generic optimal electron density mechanism for H on W(110) surface and at a vacancy in W.Both the surface and vacancy internal surface can provide a quantitative optimal electron density of~0.10electron/(A)3 for H binding to make H stability.We believe that such a mechanism is also applicable to other surfaces such as W( 100) surface because of the (100) surface also providing an optimal electron density for H binding,and further likely actions on other metals.
基金Project supported by the National Natural Science Foundation of China(Grant No.51101135)
文摘The diffusion behaviours of hydrogen （H）, deuterium （D）, and tritium （T） from W（110） surface into bulk and in bulk W are investigated using first-principles calculations combined with simplified models. The diffusion energy barrier is shown to be 1.87 eV from W（110） surface to the subsurface, along with a much reduced barrier of 0.06 eV for the reverse diffusion process. After H enters into the bulk, its diffusion energy barrier with quantum correction is 0.19 eV. In terms of the diffusion theory presented by Wert and Zener, the diffusion pre-exponential factor of H is calculated to be 1.57×10-7 m2.s-1, and it is quantitatively in agreement with the experimental value of 4.1×10-7 m2.s-1. Subsequently, according to mass dependence （√1/m） of H isotope effect, the diffusion pre-exponential factors of D and T are estimated to be 1.11×10-7 m2.s-1 and 0.91×10-7 m2.s-1, respectively.
