THE STRUCTURE OF IRON IN EARTH’S INNER CORE

DOI: 10.1126/science.1194662
Journal: Scicence
Year of Publication: 2010
Volume: 330
Issue: 6002
Authors: Yasufumi Umena, Keisuke Kawakami, Jian-Ren She, and Nobuo Kamiya

Abstruct

Earth’s solid inner core is mainly composed of iron (Fe). Because the relevant ultrahigh pressure and temperature conditions are difficult to produce experimentally, the preferred crystal structure of Fe at the inner core remains uncertain. Static compression experiments showed that the hexagonal close-packed (hcp) structure of Fe is stable up to 377 gigapascals and 5700 kelvin, corresponding to inner core conditions. The observed weak temperature dependence of the c/a axial ratio suggests that hcp Fe is elastically anisotropic at core temperatures. Preferred orientation of the hcp phase may explain previously observed inner core seismic anisotropy.

Keyword:
Iron, Temperature, Anisotropy