Liquidus determination of the Fe-S and (Fe, Ni)-S systems at 14 and 24 GPa: Implications for the Mercurian core

Mercury has fascinated researchers for decades due to its sizable metallic core and weak magnetic field. The behavior of Fe-S and (Fe, Ni)-S systems provides constraints on core conditions and regimes of solidification to predict magnetic field strength. In this study, we investigate the melting behavior of the (Fe, Ni)-S system, a candidate composition to model the Mercurian core. We observe that the Fe-S liquidus has an inflection point at similar to 10 wt.% S at 14 GPa and similar to 11.5 wt.% S at 24 GPa, while (Fe, Ni)-S does not. At 24 GPa, Ni may lower the melting point of the Fe-S system by as much as 300 degrees C, indicating that solidification models and adiabatic calculations must account for the presence of Ni.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the melting behavior of the (Fe, Ni)-S system as a candidate composition to model the Mercurian core. Results show that Ni can lower the melting point of the Fe-S system by up to 300 degrees C at 24 GPa, highlighting the importance of accounting for the presence of Ni in solidification models and adiabatic calculations.