Ozawa T, Sugisawa Y, Komatsu Y, Shimizu R, Hitosugi T, Sekiba D, Yamauchi K, Hamada I, Fukutani K
Institute of Industrial Science, The University of Tokyo, Meguro, Tokyo, Japan.
Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Nat Commun. 2024 Nov 14;15(1):9558. doi: 10.1038/s41467-024-53838-6.
Hydrogen, the smallest and lightest element, readily permeates a variety of materials and modulates their physical properties. Identification of the hydrogen lattice location and its amount in crystals is key to understanding and controlling the hydrogen-induced properties. Combining nuclear reaction analysis (NRA) with the ion channeling technique, we experimentally determined the locations of H and D in epitaxial nanofilms of titanium hydrides from the analysis of the two-dimensional angular mappings of NRA yields. Here we show that 11 at% of H are located at the octahedral site with the remaining H atoms in the tetrahedral site. Density functional theory calculations revealed that the structures with the partial octahedral site occupation are stabilized by the Fermi level shift and Jahn-Teller effect induced by hydrogen. In contrast, D was found to solely occupy the tetrahedral site owing to the mass effect on the zero-point vibrational energy. These findings suggest that site occupation of hydrogen can be controlled by changing the isotope mixture ratio, which leads to promising manifestation of novel hydrogen-related phenomena.
氢是最小且最轻的元素，它能轻易渗透多种材料并调节其物理性质。确定氢在晶体中的晶格位置及其含量是理解和控制氢诱导性质的关键。我们将核反应分析（NRA）与离子沟道技术相结合，通过对NRA产额的二维角度映射分析，实验确定了氢化钛外延纳米薄膜中H和D的位置。在此我们表明，11 at%的H位于八面体位置，其余H原子位于四面体位置。密度泛函理论计算表明，部分八面体位置占据的结构通过氢诱导的费米能级移动和 Jahn - Teller 效应得以稳定。相比之下，由于质量对零点振动能的影响，发现D仅占据四面体位置。这些发现表明，通过改变同位素混合比可以控制氢的位置占据，这为新型氢相关现象的出现带来了希望。
