Discovery of a hexagonal ultradense hydrous phase in (Fe,Al)OOH
- Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
- Carnegie Inst. of Science, Washington, DC (United States). Geophysical Lab., High Pressure Collaborative Access Team
- Center for High Pressure Science and Technology Advanced Research, Shanghai (China); Carnegie Inst. of Science, Washington, DC (United States). Geophysical Lab.
A deep lower-mantle (DLM) water reservoir depends on availability of hydrous minerals which can store and transport water into the DLM without dehydration. Recent discoveries found hydrous phases AlOOH (Z= 2) with a CaCl2-type structure and FeOOH (Z= 4) with a cubic pyrite-type structure stable under the high-pressure–temperature (P-T) conditions of the DLM. Our experiments at 107–136 GPa and 2,400 K have further demonstrated that (Fe,Al)OOH is stabilized in a hexagonal lattice. By combining powder X-ray-diffraction techniques with multigrain indexation, we are able to determine this hexagonal hydrous phase witha= 10.5803(6) Å andc= 2.5897(3) Å at 110 GPa. Hexagonal (Fe,Al)OOH can transform to the cubic pyrite structure at lowTwith the same density. Furthermore, the hexagonal phase can be formed when δ-AlOOH incorporates FeOOH produced by reaction between water and Fe, which may store a substantial quantity of water in the DLM.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- National Natural Science Foundation of China (NSFC); Foundation of President of China Academy of Engineering Physics; National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
- Grant/Contract Number:
- 41574080; U1530402; 201402032; EAR-1345112; EAR-1447438; NA0001974; FG02-99ER45775; AC02-06CH11357
- OSTI ID:
- 1430340
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, Issue 12; ISSN 0027-8424
- Publisher:
- National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
First‐Principles Study of FeO 2 H x Solid and Melt System at High Pressures: Implications for Ultralow‐Velocity Zones
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journal | May 2019 |
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