Earth's Inner Core Contains Gradient of Super‑Ionic Hydrogen, Study Finds

New quantum‑mechanical simulations published in the Proceedings of the National Academy of Sciences reveal that hydrogen exists in a super‑ionic state within Earth’s inner core. The research shows hydrogen is not uniformly distributed but forms a concentration gradient, with the highest proportion (about 16 % of atoms) at the boundary between the solid inner core and the liquid outer core, decreasing to roughly 9 % toward the centre.

The super‑ionic hydrogen flows like a liquid through solid iron under the extreme pressures (over 3 million atmospheres) and temperatures (around 5 200 °C) found 3 200 miles beneath the surface. This behavior may influence the planet’s magnetic field and helps explain anomalous seismic wave properties observed in the core. The study models hydrogen in three phases—solid, liquid, and super‑ionic—and constructs a phase diagram that supports the prevailing hexagonal close‑packed (hcp) iron structure for the inner core. The authors note that other light elements could also be present, but hydrogen appears to play a significant role in the core’s composition and dynamics.