论文标题
缺陷α-Al2O3表面上的氢渗透：DFT计算
Hydrogen permeation on defected α-Al2O3 surfaces: DFT calculations
论文作者
论文摘要
实现受控融合能量的关键挑战之一是triftium自给自足。氢渗透屏障（HPB）的应用被认为是自给自足的必要条件。 α-Al2O3目前是HPB的候选材料。然而，对于α-Al2O3的一个关键问题是，其渗透率降低因子（PRF）将在离子或中子辐照后大幅下降。目前，关于相关机制知之甚少。为了阐明这个问题，通过密度函数理论研究了氢在缺陷α-AL2O3表面上的动力学和能量变化。对于完美的α-AL2O3表面，结果表明，从最外面层到地下层的氢迁移的障碍是最高的，这使得该迁移步骤成为限制速率限制过程。相比之下，表面点缺陷大大降低了此最大障碍。因此，氢可以通过表面缺陷优先渗入材料内部。这些发现可以帮助解释辐射下PRF的显着降低的可能机制。
One of the key challenges to realize controlled fusion energy is tritium self-sufficiency. The application of hydrogen permeation barrier (HPB) is considered to be necessary for tritium self-sufficiency. α-Al2O3 is currently a candidate material for HPB. However, a crucial issue for α-Al2O3 is that its permeability reduction factor (PRF) will dramatically drop after ion or neutron irradiations. At present, little is known about the relevant mechanism. In order to shed light on this issue, the kinetics and energetic changes of hydrogen on defected α-Al2O3 surfaces in comparison with perfect α-Al2O3 surfaces were studied by density functional theory. For perfect α-Al2O3 surfaces, the results show that the barrier for hydrogen migration from the outermost layer into the subsurface layer is the highest, making this migration step to be a rate limiting process. In contrast, surface point defects dramatically reduce this maximum barrier. Consequently, hydrogen can preferentially permeate into the interior of the material through surface defects. The findings can help explain the possible mechanism of significant decrease of PRF under radiation.
