The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

• Published in: Geophysical research letters Vol. 44; no. 16; pp. 8254 - 8259
• Main Authors: Suehiro, Sho, Ohta, Kenji, Hirose, Kei, Morard, Guillaume, Ohishi, Yasuo
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.08.2017
• Subjects: Alloying effects; Alloying elements; Alloys; Close packed lattices; Conductivity; Cores; Electrical resistivity; Ferrous alloys; Geochemistry; high pressure; impurity resistivity; Iron; Mars; Mars's and Earth's core; Planetary cores; Planetary evolution; Planets; Sulfur; Terrestrial planets; Thermal evolution
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2017GL074021

Cosmochemical and geochemical studies suggest sulfur (S) as a light alloying element in the iron‐rich cores of telluric planets, but there is no report of sulfur's alloying effect on the electrical and thermal transport properties of iron (Fe); a subject that is closely related to the dynamo action and thermal evolution of planetary cores. We measured the electrical resistivity of hexagonal‐closed‐packed (hcp) structured Fe alloy containing 3 wt. % silicon (Si) and 3 wt. % S up to 110 GPa at 300 K. Combined with the reported resistivities of hcp Fe and hcp Fe‐Si alloy, we determined the impurity resistivity of S in a hcp Fe matrix at high pressures. The obtained impurity resistivity of S is found to be smaller than that of Si. Therefore, S is a weaker influence on the conductivity of Fe alloy, even if S is a major light element in the planetary cores. Key Points Electrical resistivity of hcp Fe‐Si‐S alloy was measured up to 110 GPa Using previous study on pure Fe and Fe‐Si alloys, impurity resistivity of S in hcp iron was determined Thermal conductivity profiles of the Mars's and Earth's cores including S were proposed