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Title: Synthesis of sodium polyhydrides at high pressures

Archetypal ionic NaH is the only known compound of sodium and hydrogen. Application of high pressure is known to promote states with higher atomic coordination, but extensive searches for polyhydrides with unusual stoichiometry have had only limited success in spite of several theoretical predictions. Here we report the first observation of the formation of polyhydrides of Na (NaH3 and NaH7) above 40 GPa and 2,000 K. Moreover, we combine synchrotron X-ray diffraction and Raman spectroscopy in a laser-heated diamond anvil cell and theoretical random structure searching, which both agree on the stable structures and compositions. Our results support the formation of multicenter bonding in a material with unusual stoichiometry. These results are applicable to the design of new energetic solids and high-temperature superconductors based on hydrogen-rich materials.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.
  2. Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.; Center for High Pressure Science and Technology Advanced Research, Shanghai (China)
  3. Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Univ. College London, Bloomsbury (United Kingdom). Dept. of Physics and Astronomy; Univ. of Cambridge (United Kingdom). Dept. of Materials Science and Metallurgy
  5. Univ. of Cambridge (United Kingdom). Cavendish Lab.
  6. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources
  7. Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.; Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Solid State Physics
Publication Date:
OSTI Identifier:
1321433
Report Number(s):
LLNL-JRNL--697920
Journal ID: ISSN 2041-1723
Grant/Contract Number:
AC52-07NA27344; FG02-02ER45955; FG02-99ER45775; SC0001057; AC02-06CH11357; FG02-94ER14466
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 08 HYDROGEN; 58 GEOSCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY chemical sciences; inorganic chemistry; materials science