Shock synthesis of quasicrystals with implications for their origin in asteroid collisions
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 CuAl5 , (Mg0.75 Fe2+ 0.25)2 SiO4 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 Al68-73 Fe11-16 Cu10-12 Cr1-4 Ni1-2 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.
Asimow, P. D.,
Hollister, L. S.,
Steinhardt, P. J.
Shock synthesis of quasicrystals with implications for their origin in asteroid collisions.
Proceedings of the National Academy of Sciences of the United States of America, 113(26),