Center for High Pressure Science and Technology Advanced Research, 1690 Cailun Rd., Bldg. 6, Pudong, Shanghai 201203, People's Republic of China.
School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom.
J Chem Phys. 2018 Apr 14;148(14):144310. doi: 10.1063/1.5026535.
In situ high-pressure high-temperature X-ray powder diffraction studies of the cobalt-hydrogen system reveal the direct synthesis of both the binary cobalt hydride (CoH) and a novel cobalt dihydride (CoH). We observe the formation of fcc CoH at pressures of 4 GPa, which persists to pressures of 45 GPa. At this pressure, we see the emergence with time of a further expanded fcc lattice, which we identify as CoH, where the hydrogen atoms occupy the tetrahedral vacancies. We have explored alternative synthesis routes of CoH and can lower the synthesis pressure to 35 GPa by the application of high temperature. CoH is stable to at least 55 GPa and decomposes into CoH below 10 GPa, releasing molecular hydrogen before further decomposing completely into its constituent elements below 3 GPa. As a first-row transition metal, cobalt has a relatively lower mass than other hydride-forming transition metals, and as a result, CoH has a high hydrogen content of 3.3 wt. % and a volumetric hydrogen density of 214 g/l.
原位高压高温 X 射线粉末衍射研究钴-氢体系揭示了二元钴氢化物 (CoH) 和一种新型钴二氢化物 (CoH) 的直接合成。我们观察到在 4 GPa 的压力下形成 fcc CoH，其在 45 GPa 的压力下仍然存在。在这个压力下，我们随着时间的推移观察到进一步扩展的 fcc 晶格的出现，我们将其鉴定为 CoH，其中氢原子占据四面体空位。我们已经探索了 CoH 的替代合成途径，并通过施加高温将合成压力降低到 35 GPa。CoH 在至少 55 GPa 下稳定，在 10 GPa 以下分解为 CoH，在 3 GPa 以下完全分解为其组成元素之前释放出分子氢。作为第一过渡金属，钴的质量相对低于其他形成氢化物的过渡金属，因此，CoH 的氢含量高达 3.3wt.%，体积氢密度为 214 g/L。
