EPP

In the last decades, global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core. Plenty of seismic studies have confirmed the anisotropy presents hemispherical variations in inner core. Here we report the effect of light elements on the anisotropy of hcp iron under inner core conditions based on ab initio molecular dynamics calculations. We found that light elements have significant effects on the density, sound velocities, and the anisotropy of hcp-Fe-X (X = C, O, Si, and S) binary alloy. For these binary alloys, the anisotropy depends on combined effects of temperature and the type of light element. Furthermore, there is a certain increase of the anisotropy strength with the increasing temperature. Alloying iron with some light elements such as C or O actually does not improve but reduces the strength of anisotropy of pure iron at high temperatures. Oppositely, light element S can significantly enhance the elastic anisotropy strength of hcp-Fe.