Hydrogen at the mass ppm level causes hydrogen embrittlement in metallic materials, but experimentally elucidating the hydrogen trapping sites is extremely difficult. We exploit the fact that positive muons can act as light isotopes of hydrogen to study the trapping state of hydrogen in matter. Zero-field muon spin relaxation experiments and density functional theory (DFT) calculations of the hydrogen trapping energy are carried out for AlMn. The DFT calculations reveal four possible trapping sites for hydrogen in AlMn, at which the hydrogen trapping energies are 0.168 (site 1), 0.312 (site 2), 0.364 (site 3), and 0.495 (site 4) in units of eV/atom. The variations in the deduced dipole field width (Δ) with temperature indicate noticeable changes at 94, 193, and 236 K. Considering the site densities, the observed Δ change temperatures are interpreted as muon trapping at sites 1, 3, and 4.

中文翻译：

---

结合 μ 子自旋弛豫和 DFT 模拟 Al6Mn 中的氢捕获

质量 ppm 级的氢会导致金属材料发生氢脆，但通过实验阐明氢捕获位点极其困难。我们利用正μ子可以充当氢的轻同位素这一事实来研究氢在物质中的捕获状态。对AlMn进行了零场μ子自旋弛豫实验和氢捕获能的密度泛函理论（DFT）计算。DFT 计算揭示了 AlMn 中四个可能的氢捕获位点，其中氢捕获能分别为 0.168（位点 1）、0.312（位点 2）、0.364（位点 3）和 0.495（位点 4），单位为 eV/atom 。推导的偶极子场宽度 (Δ) 随温度的变化表明在 94、193 和 236 K 处有明显变化。考虑到位点密度，观察到的 Δ 变化温度被解释为位点 1、3 和 4 处的 μ 子捕获。