Melting and resistivity of iron at Earth core conditions using pulsed Joule heating

The melting temperature and electrical resistivity of iron at high pressure are essential for understanding Earth's core. Here we use a new high-pressure method - microsecond pulsed Joule heating in diamond anvil cells - to identify melting and measure resistivity of solid and liquid iron. More than 300 reproducible melting measurements indicate a surprisingly shallow melting curve, reaching 6 K/GPa and 4160 ± 80 K at 200 GPa. Extrapolating in pressure and iron alloy composition, and combining with our 76 [Formula: see text] cm measurement of liquid iron's resistivity, we infer a relatively cold core-mantle boundary (3430 K) with a low adiabatic outer core heat flow (9.8 TW). This suggests thermal convection alone could have powered the geodynamo prior to inner core formation and that today's lowermost mantle is fully solid.

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Publication Details

Journal
Science
Published
2026-11-08
DOI
https://doi.org/10.1126/science.aeh5267
Primary Topic
High-pressure geophysics and materials
Type
article
Field-Weighted Citation Impact
0.00

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article

Melting and resistivity of iron at Earth core conditions using pulsed Joule heating

Michael J. Walter, Francesca Miozzi, Vitali B. Prakapenka, Stella Chariton et al.
Science
High-pressure geophysics and materials
article

Melting and resistivity of iron at Earth core conditions using pulsed Joule heating

Michael J. Walter, Francesca Miozzi, Vitali B. Prakapenka, Stella Chariton, Nathan Sime, Ryan V. Tappero, Vasilije V. Dobrosavljevic, Peter E. van Keken, Jing Yang, Yue Meng, Peter Driscoll, Suzy Vitale, Zachary M. Geballe, Wenjun Liu
article en

Abstract

The melting temperature and electrical resistivity of iron at high pressure are essential for understanding Earth's core. Here we use a new high-pressure method - microsecond pulsed Joule heating in diamond anvil cells - to identify melting and measure resistivity of solid and liquid iron. More than 300 reproducible melting measurements indicate a surprisingly shallow melting curve, reaching 6 K/GPa and 4160 ± 80 K at 200 GPa. Extrapolating in pressure and iron alloy composition, and combining with our 76 [Formula: see text] cm measurement of liquid iron's resistivity, we infer a relatively cold core-mantle boundary (3430 K) with a low adiabatic outer core heat flow (9.8 TW). This suggests thermal convection alone could have powered the geodynamo prior to inner core formation and that today's lowermost mantle is fully solid.

Science
Argonne National Laboratory (US), Carnegie Institution for Science (US), Brookhaven National Laboratory (US), University of Pavia (IT), ETH Zurich (CH), University of Chicago (US), Earth and Planets Laboratory (US), National Synchrotron Light Source II (US), Advanced Photon Source (US)
National Science Foundation, Carnegie Institution for Science
High-pressure geophysics and materials
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