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Title: Quasicrystals at extreme conditions: The role of pressure in stabilizing icosahedral Al 63Cu 24Fe 13 at high temperature

Icosahedrite, the first natural quasicrystal with composition Al 63Cu 24Fe 13, was discovered in several grains of the Khatyrka meteorite, a unique CV3 carbonaceous chondrite. The presence in the meteorite fragments of icosahedrite strictly associated with high-pressure phases like ahrensite and stishovite indicates a formation conditions at high pressures and temperatures, likely during an impact-induced shock occurred in contact with the reducing solar nebula gas. In contrast, previous experimental studies on the stability of synthetic icosahedral AlCuFe, which were limited to ambient pressure, indicated incongruent melting at ~1123 K, while high-pressure experiments carried out at room temperature showed structural stability up to about 35 GPa. These data are insufficient to experimentally constrain the formation and stability of icosahedrite under extreme conditions. Here we present the results of in situ high pressure experiments using diamond anvil cells of the compressional behavior of synthetic icosahedrite up to ~50 GPa at room temperature. Simultaneous high P-T experiments have been also carried out using both laser-heated diamond anvil cells combined with in situ synchrotron X-ray diffraction (at ~42 GPa) and multi-anvil apparatus (at 21 GPa) to investigate the structural evolution of icosahedral Al 63Cu 24Fe 13 and crystallization of possible coexisting phases. The resultsmore » demonstrate that the quasiperiodic symmetry of icosahedrite is retained over the entire experimental pressure range explored. In addition, we show that pressure acts to stabilize the icosahedral symmetry at temperatures much higher than previously reported. Based on our experimental study, direct crystallization of Al-Cu-Fe quasicrystals from an unusual Al-Cu-rich melt would be possible but limited to a narrow temperature range beyond which crystalline phases would form, like those observed in the Khatyrka meteorite. Here, an alternative mechanism would consist in late formation of the quasicrystal after crystallization and solid-solid reaction of Al-rich phases. In both cases, linking our results with observations in nature, quasicrystals are expected to preserve their structure even after hypervelocity impacts that involve simultaneous high pressures and temperatures, thus proving their cosmic stability.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [7] ;  [6]
  1. Carnegie Institution of Washington, Washington, D.C. (United States); Ehime Univ., Matsuyama (Japan); Tokyo Institute of Technology, Tokyo (Japan)
  2. Univ. di Firenze, Florence (Italy)
  3. Carnegie Inst. of Washington, Argonne, IL (United States)
  4. The Univ. of Chicago, Chicago, IL (United States)
  5. Carnegie Institution of Washington, Washington, D.C. (United States); Center for High Pressure Science and Technology Advanced Research, Shanghai (People's Republic of China)
  6. Carnegie Institution of Washington, Washington, D.C. (United States)
  7. Princeton Univ., Princeton, NJ (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
American Mineralogist
Additional Journal Information:
Journal Volume: 100; Journal Issue: 11-12; Journal ID: ISSN 0003-004X
Mineralogical Society of America
Research Org:
Carnegie Institution of Washington, Washington, D.C. (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
36 MATERIALS SCIENCE; icosahedrite; quasicrystals; CV3 chondrite; redox; Khatyrka meteorite; solar nebula
OSTI Identifier: