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Published June 28, 2016 | Published + Supplemental Material
Journal Article Open

Shock synthesis of quasicrystals with implications for their origin in asteroid collisions

Abstract

We designed a plate impact shock recovery experiment to simulate the starting materials and shock conditions associated with the only known natural quasicrystals, in the Khatyrka meteorite. At the boundaries among CuAl_5, (Mg_(0.75)Fe^(2+)_(0.25))_2SiO_4 olivine, and the stainless steel chamber walls, the recovered specimen contains numerous micron-scale grains of a quasicrystalline phase displaying face-centered icosahedral symmetry and low phason strain. The compositional range of the icosahedral phase is Al_(68–73)Fe_(11–16)Cu_(10–12)Cr_(1–4)Ni_(1–2) and extends toward higher Al/(Cu+Fe) and Fe/Cu ratios than those reported for natural icosahedrite or for any previously known synthetic quasicrystal in the Al-Cu-Fe system. The shock-induced synthesis demonstrated in this experiment reinforces the evidence that natural quasicrystals formed during a shock event but leaves open the question of whether this synthesis pathway is attributable to the expanded thermodynamic stability range of the quasicrystalline phase at high pressure, to a favorable kinetic pathway that exists under shock conditions, or to both thermodynamic and kinetic factors.

Additional Information

© 2016 National Academy of Sciences. Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved May 6, 2016 (received for review January 7, 2016) P.D.A. is supported by US National Science Foundation (NSF) Award EAR-1426526. L.B. is funded with the "60%2013" research funds from the University of Firenze, Italy. C.L. and P.J.S. are supported, in part, by NSF-MRSEC Program Grants DMR-0820341 through New York University and DMR-0819860 through the Princeton Center for Complex Materials. SEM, EDS, EBSD, and EPMA analyses were carried out at the Caltech GPS Division Analytical Facility, which is supported, in part, by NSF Grants EAR-0318518 and DMR-0080065. Author contributions: P.D.A. and P.J.S. designed research; P.D.A., C.L., L.B., C.M., and O.T. performed research; P.D.A., C.L., L.B., C.M., O.T., and L.S.H. analyzed data; and P.D.A., L.B., and P.J.S. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. Data deposition: Crystallographic data on quasicrystals is available from the authors upon request. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1600321113/-/DCSupplemental.

Attached Files

Published - PNAS-2016-Asimow-7077-81.pdf

Supplemental Material - pnas.201600321SI.pdf

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August 22, 2023
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