Iron, a primary component of the Earth’s core, exhibits unique behaviours under extreme temperatures and pressures. Recent research has examined its melting temperature and phase stability under conditions mirroring those at the Earth’s core. Findings from advanced experiments involving ultrafast X-ray absorption spectroscopy have highlighted significant revelations about the structural and thermal properties of iron. These discoveries hold potential to refine the understanding of the Earth’s internal structure and geodynamics, providing valuable data about the processes shaping the planet’s evolution.

Advanced Study of Iron Using X-ray Spectroscopy

According to a study published in Physical Review Letters, researchers from the European Synchrotron Radiation Facility (ESRF) in Grenoble and other institutes globally investigated the microscopic behaviour of iron under high-pressure and high-temperature conditions. The experiments were conducted at the ESRF’s High-Power Laser Facility, combining high-power lasers with ultrafast X-ray absorption spectroscopy to explore the phase diagram of iron.

Sofia Balugani, the lead researcher, noted in a statement to Phys.org that the study aimed to determine iron’s melting curve and structural changes at pressures reaching 240 GPa. These conditions are comparable to those near the Earth’s inner core boundary, offering insights into how the liquid outer core transitions to the solid inner core.

Key Findings and Implications for Geodynamics

Iron’s phase was identified as hexagonal close-packed (hcp) at 240 GPa and 5,345 K, just before melting. This finding, as highlighted by Balugani, contradicts earlier theoretical predictions favouring a body-centred cubic (bcc) structure. The study also provided a new methodology for determining bulk temperatures of metals under extreme conditions using X-ray absorption spectroscopy.

The research has opened pathways for studying iron alloys at even higher pressures and temperatures, potentially enhancing knowledge of Earth’s core dynamics and contributing to nuclear fusion studies. Further exploration of iron alloys is anticipated to shed light on telluric exoplanets and the broader implications of planetary geodynamics.