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Title: High-pressure phase transitions of α-quartz under nonhydrostatic dynamic conditions: A reconnaissance study at PETRA III

Hypervelocity collisions of solid bodies occur frequently in the solar system and affect rocks by shock waves and dynamic loading. A range of shock metamorphic effects and high-pressure polymorphs in rock-forming minerals are known from meteorites and terrestrial impact craters. In this paper, we investigate the formation of high-pressure polymorphs of α-quartz under dynamic and nonhydrostatic conditions and compare these disequilibrium states with those predicted by phase diagrams derived from static experiments under equilibrium conditions. We create highly dynamic conditions utilizing a mDAC and study the phase transformations in α-quartz in situ by synchrotron powder X-ray diffraction. Phase transitions of α-quartz are studied at pressures up to 66.1 and different loading rates. At compression rates between 0.14 and 1.96 GPa s -1, experiments reveal that α-quartz is amorphized and partially converted to stishovite between 20.7 GPa and 28.0 GPa. Therefore, coesite is not formed as would be expected from equilibrium conditions. With the increasing compression rate, a slight increase in the transition pressure occurs. The experiments show that dynamic compression causes an instantaneous formation of structures consisting only of SiO 6 octahedra rather than the rearrangement of the SiO 4 tetrahedra to form a coesite. Although shock compression rates aremore » orders of magnitude faster, a similar mechanism could operate in impact events.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [2] ;  [5] ;  [6] ;  [7]
  1. Albert Ludwigs Univ. of Freiburg (Germany). Inst. of Geo and Environmental Sciences and Dept. of Geology and Crystallography
  2. Friedrich Schiller Univ., Jena (Germany). Inst. of Geosciences and Dept. of Mineralogy
  3. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
  4. Albert Ludwigs Univ. of Freiburg (Germany). Inst. of Geo and Environmental Sciences and Dept. of Crystallography
  5. Stony Brook Univ., NY (United States). Mineral Physics Inst.; Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  6. UniLaSalle, Beauvais (France). Dept. of Geosciences
  7. Albert Ludwigs Univ. of Freiburg (Germany). Inst. of Geo and Environmental Sciences and Dept. of Geology
Publication Date:
Report Number(s):
BNL-203468-2018-JAAM
Journal ID: ISSN 1086-9379
Grant/Contract Number:
SC0012704; 830/14‐1; LA830/17‐1
Type:
Accepted Manuscript
Journal Name:
Meteoritics and Planetary Science
Additional Journal Information:
Journal Volume: 52; Journal Issue: 7; Journal ID: ISSN 1086-9379
Publisher:
Wiley
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); German Research Foundation (DFG)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 36 MATERIALS SCIENCE; 79 ASTRONOMY AND ASTROPHYSICS
OSTI Identifier:
1433951