title: The formation of H bubbles at small-angle tilt grain boundaries in W films.
abstract: The accumulation of H at the small-angle tilt grain boundary (GB) in the W(001) surface is investigated, on the basis of the first-principles calculations. By exploring the solution and diffusion behaviors of H at the GB, we find that the small-angle GB can capture the H atoms nearby, serving as a nucleation site of H bubbles. With the increasing number of trapped H atoms, the GB expands gradually, and the GBs can be unripped with an areal density of H up to 5.0 × 1015H atoms per cm2, leading to the formation of H bubbles. Moreover, H2molecules are observed, when the areal density of H atoms in GB is over 6.6 × 1015atoms per cm2. According to our calculations, we propose a possible formation mechanism of H bubbles observed in the experiment, which is valuable for improving the service performance of W as a plasma-facing material in nuclear fusion reactors.
authors.affiliation: Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. hyhe@ustc.edu.cn.
authors.forename: Zhihai
authors.initials: Z
authors.lastname: He
authors.affiliation: Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. hyhe@ustc.edu.cn.
authors.forename: H Y
authors.initials: HY
authors.lastname: He
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: R
authors.initials: R
authors.lastname: Ding
authors.affiliation: Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. hyhe@ustc.edu.cn and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: B C
authors.initials: BC
authors.lastname: Pan
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
authors.forename: J L
authors.initials: JL
authors.lastname: Chen