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Title: Synthesis and Stability of Lanthanum Superhydrides

Abstract

Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.

Authors:
ORCiD logo [1];  [1];  [2];  [1];  [1];  [3];  [1];  [4]
  1. Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA
  2. Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Permanent address: HP&SRPD, Bhabha Atomic Research Center, Mumbai-85 India
  3. HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne IL 60439 USA
  4. Institute of Materials Science and Department of Civil and Environmental Engineering, The George Washington University, Washington DC 20052 USA
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1418052
Resource Type:
Journal Article
Resource Relation:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 57; Journal Issue: 3
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Geballe, Zachary M., Liu, Hanyu, Mishra, Ajay K., Ahart, Muhtar, Somayazulu, Maddury, Meng, Yue, Baldini, Maria, and Hemley, Russell J. Synthesis and Stability of Lanthanum Superhydrides. United States: N. p., 2017. Web. doi:10.1002/anie.201709970.
Geballe, Zachary M., Liu, Hanyu, Mishra, Ajay K., Ahart, Muhtar, Somayazulu, Maddury, Meng, Yue, Baldini, Maria, & Hemley, Russell J. Synthesis and Stability of Lanthanum Superhydrides. United States. doi:10.1002/anie.201709970.
Geballe, Zachary M., Liu, Hanyu, Mishra, Ajay K., Ahart, Muhtar, Somayazulu, Maddury, Meng, Yue, Baldini, Maria, and Hemley, Russell J. Fri . "Synthesis and Stability of Lanthanum Superhydrides". United States. doi:10.1002/anie.201709970.
@article{osti_1418052,
title = {Synthesis and Stability of Lanthanum Superhydrides},
author = {Geballe, Zachary M. and Liu, Hanyu and Mishra, Ajay K. and Ahart, Muhtar and Somayazulu, Maddury and Meng, Yue and Baldini, Maria and Hemley, Russell J.},
abstractNote = {Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.},
doi = {10.1002/anie.201709970},
journal = {Angewandte Chemie (International Edition)},
number = 3,
volume = 57,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2017},
month = {Fri Dec 15 00:00:00 EST 2017}
}