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Quasicrystals at extreme conditions: The role of pressure in stabilizing icosahedral Al63Cu24Fe13at high temperature
- Source :
- American Mineralogist. 100:2412-2418
- Publication Year :
- 2015
- Publisher :
- Mineralogical Society of America, 2015.
-
Abstract
- Icosahedrite, the first natural quasicrystal with composition Al 63 Cu 24 Fe 13 , was discovered in several grains of the Khatyrka meteorite, a CV3 carbonaceous chondrite. The presence of icosahedrite associated with high-pressure phases like ahrensite and stishovite indicates formation at high pressures and temperatures due to an impact-induced shock. Previous experimental studies on the stability of synthetic icosahedral AlCuFe have either been limited to ambient pressure, for which they indicate incongruent melting at ~1123 K, or limited to room-temperature, for which they indicate structural stability up to about 35 GPa. These data are insufficient to experimentally constrain the formation and stability of icosahedrite under the conditions of high pressure and temperature that formed the Khatyrka meteorite. Here we present the results of room-temperature, high-pressure diamond-anvil cells measurements of the compressional behavior of synthetic icosahedrite up to ~50 GPa. High P - T experiments were 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 and crystallization of possible coexisting phases. The results demonstrate that the quasiperiodic order of icosahedrite is retained over the P - T range explored. We find that pressure acts to stabilize the icosahedral symmetry at temperatures much higher than previously reported. Direct solidification of AlCuFe quasicrystals from an unusual Al-Cu-rich melt is possible but it is limited to a narrow temperature range. Alternatively, quasicrystals may form after crystallization through solid-solid reactions of Al-rich phases. In either case, our results show that quasicrystals can preserve their structure even after hypervelocity impacts spanning a broad range of pressures and temperatures.
- Subjects :
- Icosahedrite
Materials science
Incongruent melting
Icosahedral symmetry
Quasicrystal
Atmospheric temperature range
engineering.material
law.invention
Khatyrka meteorite
Crystallography
Geophysics
solar nebula
Geochemistry and Petrology
law
Chemical physics
icosahedrite
redox
CV3 chondrite
quasicrystals
geochemistry and petrology
geophysics
engineering
Crystallization
Stishovite
Ambient pressure
Subjects
Details
- ISSN :
- 0003004X
- Volume :
- 100
- Database :
- OpenAIRE
- Journal :
- American Mineralogist
- Accession number :
- edsair.doi.dedup.....216dd45fbfd3f5ac1c740757c3b1b70c