Earth's Core: A Superionic State Discovered

Scientists have unveiled a groundbreaking discovery about Earth's inner core, revealing it exists in a superionic state. This new understanding, reported by sciencedaily on December 10, 2025, challenges previous models of our planet's deepest layer. The research indicates carbon atoms flow freely within a solid iron lattice.

In this unusual superionic state, carbon atoms exhibit liquid-like mobility, diffusing rapidly through a rigid iron framework. This unique behavior makes the inner core unexpectedly soft, a characteristic that has long puzzled geophysicists, as noted by SciTechDaily on February 9, 2022.

This discovery provides a strong explanation for decades of perplexing seismic observations, which indicated the inner core was softer than a conventional solid. Prof. Youjun Zhang of Sichuan University stated that their experimental findings show a remarkably low shear velocity in iron-carbon alloys under core conditions.

The investigation was led by Prof. Youjun Zhang and Dr. Yuqian Huang of Sichuan University, alongside Prof. Yu He from the Institute of Geochemistry, Chinese Academy of Sciences. Their work, published in National Science Review, demonstrated this superionic phase under extreme pressure and heat.

The findings fundamentally reshape current models of Earth's interior, moving away from a static, rigid view of the inner core towards a more dynamic one, Prof. Zhang explained to ScienceDaily. This dynamic model has significant implications for understanding the planet's geological processes.

Beyond Earth, this breakthrough could also apply to other rocky planets and exoplanets, offering new insights into their internal structures and evolution. Understanding this hidden state of matter brings scientists closer to unlocking secrets of Earth-like planetary interiors, as highlighted by ScienceDaily.

• Historical Context of the Inner Core: For many years, the Earth's inner core was believed to be a solid sphere of iron and nickel, despite seismic data suggesting an unexpected softness. This paradox, where the solid center appeared both firm and pliable, has been a long-standing question in earth science, as reported by sciencedaily on December 10, 2025.

• Methodology and Experimental Evidence: The research team recreated the extreme conditions of the inner core, including pressures over 3.3 million atmospheres and temperatures comparable to the Sun's surface. They used dynamic shock compression platforms and advanced molecular dynamics simulations to observe the superionic transition in iron-carbon alloys, according to Science China Press.

• The Nature of the Superionic State: In this newly identified superionic state, iron atoms maintain a solid, ordered lattice, while lighter elements like carbon (and potentially hydrogen and oxygen) diffuse freely within it, behaving like a liquid. This hybrid state dramatically reduces the alloy's rigidity, as explained by Prof. Zhang in ScienceDaily.

• Impact on Earth's Magnetic Field: The fluid-like motion of these light elements within the inner core represents a previously overlooked energy source for the geodynamo, the mechanism generating Earth's magnetic field. Dr. Huang stated that this atomic diffusion may help power Earth's magnetic engine, according to sciencedaily.

• Explaining Seismic Anomalies: The superionic model effectively explains the inner core's puzzling seismic properties, including its low shear wave velocity and seismic anisotropy. The movement of light elements within the core can account for directional variations in seismic wave speeds, as detailed in the National Science Review study.

• Implications for Planetary Science: The discovery of a superionic phase in Earth's core has profound implications for understanding the magnetic and thermal evolution of other rocky planets and exoplanets. This new perspective could help scientists model the interiors of distant worlds more accurately, as highlighted by ScienceDaily.

• Future Research and Dynamic Core: Prof. Zhang emphasized a shift from a static to a dynamic model of the inner core. Future research will likely explore how this dynamic core influences Earth's cooling over time and how the magnetic field fluctuates, potentially even changing with the geomagnetic field, as suggested by Prof. He to Newsweek in February 2022.

• Earlier Computational Work: While the recent findings provide experimental evidence, computational models had hinted at such a state as early as February 2022. Researchers from the Chinese Academy of Sciences, including Prof. Yu He, used quantum mechanics theory to simulate conditions and predict the superionic state in iron alloys with hydrogen, oxygen, and carbon, as reported by scitechdaily.