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Title: Stability of numerous novel potassium chlorides at high pressure

K-Cl is a simple system displaying all four main types of bonding, as it contains (i) metallic potassium, (ii) elemental chlorine made of covalently bonded Cl 2 molecules held together by van der Waals forces, and (iii) an archetypal ionic compound KCl. The charge balance rule, assigning classical charges of “+1” to K and “–1” to Cl, predicts that no compounds other than KCl are possible. However, our quantum-mechanical variable-composition evolutionary simulations predict an extremely complex phase diagram, with new thermodynamically stable compounds K 3Cl, K 2Cl, K 3Cl 2, K 4Cl 3, K 5Cl 4, K 3Cl 5, KCl 3 and KCl 7. Of particular interest are 2D-metallic homologs K n+1Cl n, the presence of positively charged Cl atoms in KCl 7, and the predicted stability of KCl 3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic Pm3¯n -KCl 3 at 40–70 GPa and trigonal P3¯cl -KCl 3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl 2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Lastly, upon unloading to 10 GPa, P3¯cl -KCl 3 transforms to a yet unknownmore » structure before final decomposition to KCl and Cl 2 at near-ambient conditions.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. China Agricultural Univ., Beijing (China); State Univ. of New York, Stony Brook, NY (United States)
  2. State Univ. of New York, Stony Brook, NY (United States); Skolkovo Institute of Science and Technology, Moscow (Russia); Moscow Institute of Physics and Technology, Moscow Region (Russia)
  3. Carnegie Institution of Washington, Washington, D.C. (United States); V.S. Sobolev Institute of Geology and Mineralogoy, Novosibirsk (Russia)
  4. Carnegie Institution of Washington, Washington, D.C. (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Carnegie Institution of Washington, Washington, D.C. (United States); Institute of Solid State Physics, Hefei (China); Univ. of Science and Technology of China, Hefei (China)
  6. State Univ. of New York, Stony Brook, NY (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-691558
Journal ID: ISSN 2045-2322
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; chemical physics; structure of solids and liquids
OSTI Identifier:
1259765