Simulations Suggest Earth's Inner Core Exists in Superionic State

The Earth's innermost region, the inner core, is theorized by advanced computational modeling to host matter in a superionic state, a condition defined by the confluence of immense pressure and extreme thermal energy. This hypothesized state bears a structural analogy to the superionic ice believed to exist within the cores of ice giant planets such as Uranus and Neptune. Structurally, the inner core is an iron sphere, possessing a radius of approximately 2,500 kilometers and incorporating nickel alongside trace quantities of lighter elements like oxygen, sulfur, or carbon.

Researchers affiliated with the Chinese Academy of Sciences (CAS) employed sophisticated computer simulations rooted in quantum mechanics theory to construct a model of the conditions prevailing at the Earth's center. These extensive simulations indicated that iron alloys, when combined with light elements such as hydrogen, oxygen, and carbon, undergo a phase transition into a superionic state under the specific pressures and temperatures characteristic of the inner core. Within this novel structure, the lighter elemental components are envisioned to migrate freely, akin to a liquid, while remaining embedded within a fixed, ordered lattice framework composed of solid iron atoms.

This finding represents a significant refinement to the standard model of the planet's deepest layer, moving beyond simple solid or liquid descriptions. Geophysicist Yu He, who headed the research team at CAS, characterized this emergent finding as "quite abnormal" when discussing the results of their modeling efforts. Scientists in the field propose that this superionic structural arrangement provides a compelling explanation for the lower shear-wave velocity that seismologists consistently observe through seismic wave analysis, which accounts for the inner core's measured relative mechanical softness.

Furthermore, this refined model offers a potential mechanism to clarify the observed structural modifications within the inner core over vast geological timescales, and critically, how the convection currents that sustain Earth's protective magnetic field are generated and maintained. The ability of this model to integrate disparate geophysical data points lends it considerable scientific weight. While initial investigations into similar material states involved subjecting samples to high pressure and temperature using techniques like laser-driven diamond anvil cells, the current robust support for the superionic hypothesis stems predominantly from ab initio molecular dynamics simulations.

Direct, empirical validation of material behavior under the precise extreme conditions found at the planet's center remains an insurmountable challenge for current experimental technology, positioning the superionic state as the leading scientific hypothesis as of the latter half of 2025. The CAS team's work, published in a peer-reviewed journal, utilized high-performance computing clusters to execute these complex quantum mechanical calculations over extended simulation times, providing statistical confidence in the predicted phase transition. The research specifically focused on the melting point depression caused by the light elements, a key factor in stabilizing the superionic phase at inner core pressures exceeding 330 gigapascals.