Quantum Beam Science Center, Japan Atomic Energy Agency, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
Department of Physics, Chuo University, 21-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
Nat Commun. 2014 Sep 26;5:5063. doi: 10.1038/ncomms6063.
Hydrogen composition and occupation state provide basic information for understanding various properties of the metal-hydrogen system, ranging from microscopic properties such as hydrogen diffusion to macroscopic properties such as phase stability. Here the deuterization process of face-centred cubic Fe to form solid-solution face-centred cubic FeDx is investigated using in situ neutron diffraction at high temperature and pressure. In a completely deuterized specimen at 988 K and 6.3 GPa, deuterium atoms occupy octahedral and tetrahedral interstitial sites with an occupancy of 0.532(9) and 0.056(5), respectively, giving a deuterium composition x of 0.64(1). During deuterization, the metal lattice expands approximately linearly with deuterium composition at a rate of 2.21 Å(3) per deuterium atom. The minor occupation of the tetrahedral site is thermally driven by the intersite movement of deuterium atoms along the ‹111› direction in the face-centred cubic metal lattice.
氢的组成和占据状态为理解金属-氢体系的各种性质提供了基础信息，这些性质的范围从氢扩散等微观性质到相稳定性等宏观性质。在这里，我们使用高温高压下的原位中子衍射研究了面心立方结构 Fe 氘化为形成固溶体面心立方结构 FeDx 的过程。在完全氘化的样品中，在 988 K 和 6.3 GPa 下，氘原子占据八面体和四面体间隙位，占据度分别为 0.532(9)和 0.056(5)，给出氘的组成 x 为 0.64(1)。在氘化过程中，金属晶格随着氘的组成线性膨胀，每个氘原子的膨胀率约为 2.21 Å(3)。四面体位置的少量占据是由氘原子沿面心立方金属晶格的〈111〉方向在晶间的迁移所导致的热驱动。
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