Hydrogen isotope in erbium oxide: Adsorption, penetration, diffusion, and vacancy trapping
Hydrogen isotope in erbium oxide: Adsorption, penetration, diffusion, and vacancy trapping
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DOI：
10.1016/j.fusengdes.2015.01.002
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发表时间：
2015-03
影响因子：
1.7
通讯作者：
W. Mao;T. Chikada;A. Suzuki;T. Terai;H. Matsuzaki
中科院分区：
文献类型：
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作者：
W. Mao;T. Chikada;A. Suzuki;T. Terai;H. Matsuzaki
在这项研究中，我们报告的结果使用第一性原理密度泛函理论计算的相互作用的四个关键方面：H吸附在Er 2 O3表面，表面到亚表面渗透的H到Er 2 O3，体扩散的H在Er 2 O3，和捕获的H在空位。我们确定了表面稳定的吸附位置，发现H更喜欢转移电子到表面，并与最近的相邻四个氧原子形成共价键。对于低的H表面覆盖率（0.89 × 1014 H/cm ~ 2），立方Er_2 O_3表面需要至少1.60 eV的穿透能。此外，发现由Er 2 O3单元沿着有利方向限定的平面之间的H扩散势垒<1 1 1>非常小-为0.16 eV -而跨平面扩散所需的更高势垒为0.41 eV和1.64 eV，略高于在873 K下实验观察到的0.20 eV的扩散能垒。此外，我们预测，间隙H被捕获时，它接近一个空缺的空位缺陷表现为电子陷阱，因为H-空位缺陷被发现比本征缺陷更稳定。
In this study, we report results using first-principles density functional theory calculations for four critical aspects of the interaction: H adsorption on Er2O3surface, surface-to-subsurface penetration of H into Er2O3, bulk diffusion of H in Er2O3, and trapping of H at vacancies. We identify surface stable adsorption positions and find that H prefers to transfer electrons to the surfaces and form covalent bonds with the nearest neighboring four oxygen atoms. For low surface coverage of H as in our case (0.89 × 1014H/cm2), a penetration energy of at least 1.60 eV is required for cubic Er2O3surfaces. Further, the H diffusion barrier between the planes defined by Er2O3units along the favorable <1 1 1> direction is found to be very small – 0.16 eV – whereas higher barriers of 0.41 eV and 1.64 eV are required for diffusion across the planes, somewhat higher than the diffusion energy barrier of 0.20 eV observed experimentally at 873 K. In addition, we predict that interstitial H is exothermically trapped when it approaches a vacancy with the vacancy defect behaving as an electron trap since the H-vacancy defect is found to be more stable than the intrinsic defect.