Year: 2025
Type: preprint
Abstract: The properties and stability of hydrous phases are key to unraveling the mysteries of the water cycle in Earth's interior. Under the deep lower mantle conditions, hydrous phases transition into a superionic state. However, the influence of the superionic effect on their stability and dehydration processes remains poorly understood. Using ab initio calculations and deep-learning potential molecular dynamics simulations, we discovered a doubly superionic transition in delta-AlOOH, characterized by the highly diffusive behavior of ionic hydrogen and aluminum within the oxygen sub-lattice. These highly diffusive elements contribute significant external entropy into the system, resulting in exceptional thermostability. Free energy calculations indicate that dehydration is energetically and kinetically unfavorable when water exists in a superionic state under core-mantle boundary (CMB) conditions. Consequently, water can accumulate in the deep lower mantle over Earth's history. This deep water reservoir plays a crucial role in the global deep water and hydrogen cycles.
Source: arXiv (Cornell University)
Authors: He, Yu, Zhang, Wei, Hu, Qingyang, Sun, Shichuan, Hu, Jiaqi, Liu, Daohong, Zhou, Li, Dai, Lidong, Kim, Duck Young, Liu, Yun, Li, Heping, Mao, Ho-kwang
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6979271302
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