New aluminium hydroxide at multimegabar pressures: Implications for water reservoirs in deep planetary interiors
New aluminium hydroxide at multimegabar pressures: Implications for water reservoirs in deep planetary interiors
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DOI：
10.1016/j.icarus.2019.113539
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发表时间：
2020-03
期刊：
影响因子：
3.2
通讯作者：
M. Nishi;Y. Kuwayama;J. Tsuchiya
中科院分区：
文献类型：
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作者：
M. Nishi;Y. Kuwayama;J. Tsuchiya
氢是宇宙中最丰富的元素，在行星的结构、动力学和演化中发挥着重要作用。在地球中，氢通过大洋板块的俯冲作用以含水矿物的形式被输送到地幔深部。然而，与对地球内部深处含水相行为的广泛研究相反，对较大行星（如冰巨星和超级地球）中的含水相行为知之甚少。基于激光加热金刚石对顶砧原位X射线衍射实验和第一性原理计算，我们发现δ-AlOOH在~190 GPa下转变为具有正交对称性的新相ε-AlOOH。我们还发现，FeOOH和AlOOH形成固溶体与黄铁矿型结构在~150 GPa。这些发现澄清了一些含水相在地球核幔边界的压力之外仍然保持稳定。因此，氢可能储存在这些氢氧化物或它们潜在的高压形式中，在陆地超级地球的内部深处，以及一些冰巨人的岩石核心。
Hydrogen is the most abundant element in the universe and has played an important role in the structure, dynamics, and evolution of the planets. In the Earth, hydrogen is transported into deep mantle regions in the form of hydrous minerals via the subduction of oceanic plates. However, in contrast to the extensive studies on the behaviours of hydrous phases in the deep interior of the Earth, little is known about those in larger planets, such as ice giants and super-Earths. Based on in-situ X-ray diffraction experiments in a laser-heated diamond anvil cell as well as first principles calculations, we found that δ-AlOOH transforms into a new phase with orthorhombic symmetry, named ε-AlOOH, at ~190 GPa. We also found that FeOOH and AlOOH form solid solutions with a pyrite-type structure at ~150 GPa. These findings clarified that some hydrous phases remain stable beyond pressures found in the Earth's core-mantle boundary. Hydrogen may thus be stored in these hydroxides or their potential high-pressure forms in the deep interiors of terrestrial super-Earths, and the rocky cores of some ice giants.