High-Pressure Polymorph of Iron
- 31 July 1964
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 145 (3631) , 483-486
- https://doi.org/10.1126/science.145.3631.483
Abstract
An x-ray diffraction study of iron under pressure has shown that alpha-iron (body-centered cubic) transforms to hexagonal-close-packing (designated epsilon-iron) at 130 kb, room temperature. The volume change for the transformation is -0.20 ± 0.03 cm 3 /mole. The slope for the gamma-epsilon phase boundary has been calculated to be 2 ± 1°C/kb. The molar volume of iron decreases from 7.10 cm 3 /mole (density = 7.85 g/cm 3 ) at room pressure to 6.10 ± 0.08 cm 3 /mole (density = 9.1 ± 0.1 g/cm 3 ) at 200 kb and room temperature. The extrapolation of the gamma-epsilon phase boundary, consistent with shock wave data, suggests that it may have an influence on the properties of the earth's core.Keywords
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