Phase Diagram of Iron by in Situ X-ray Diffraction: Implications for Earth's Core
- 1 December 1995
- journal article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 270 (5241) , 1473-1475
- https://doi.org/10.1126/science.270.5241.1473
Abstract
The phase diagram of iron has been studied to 130 gigapascals (1 gigapascal = 104 atmospheres) and 3500 kelvin by a combined laser-heated diamond-anvil cell and x-ray diffraction technique that provides direct identification of the solid phases. Iron in the hexagonal close-packed (hcp) phase (ε-Fe) is stable from 50 to at least 110 gigapascals at high temperatures. The wide stability field of ε-Fe indicates that this polymorph should currently be considered the most relevant solid phase for Earth's core. The triple point between the γ, ε, and liquid phases is located at 2500 ± 200 kelvin and 50 ± 10 gigapascals. There is evidence for a phase with a double hcp structure below 40 gigapascals and for another transition above 110 gigapascals and 3000 kelvin.Keywords
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