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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 Cl2 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 K3Cl, K2Cl, K3Cl2, K4Cl3, K5Cl4, K3Cl5, KCl3 and KCl7. Of particular interest are 2D-metallic homologs Kn+1Cln, the presence of positively charged Cl atoms in KCl7, and the predicted stability of KCl3 already at nearly ambient pressures at zero Kelvin. We have synthesized cubic Pm3¯n -KCl3 at 40–70 GPa and trigonal P3¯cl -KCl3 at 20–40 GPa in a laser-heated diamond anvil cell (DAC) at temperature exceeding 2000 K from KCl and Cl2. These phases were identified using in situ synchrotron X-ray diffraction and Raman spectroscopy. Lastly, upon unloading to 10 GPa, P3¯cl -KCl3 transforms to a yet unknown structure before final decomposition to KCl and Cl2 at near-ambient conditions.
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:
OSTI Identifier:
1259765
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 Laboratory (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