A recent study suggests that superionic hydrogen — an exotic form of hydrogen that flows like a liquid and conducts electricity under extreme conditions — could be abundant in Earth’s inner core, even though it doesn’t exist anywhere else on the planet’s surface. Researchers modeled three types of superionic hydrogen, including two superionic iron-hydrogen alloys (with hydrogen flowing through different crystalline iron lattices: hexagonal close-packed, HCP, and body-centered cubic, BCC).
The modeling indicated that the HCP phase is more likely to dominate in the inner core due to greater thermodynamic stability under typical conditions. However, at extremely high temperatures (above 6,400 Kelvin) and hydrogen content (exceeding 20% at 3.6 million atmospheres of pressure), the BCC phase could become more stable. The study also revealed a radial concentration gradient: the hydrogen composition «drops sharply» when moving from the outer core toward the center of the inner core. This suggests that hydrogen is continuously redistributed between the inner and outer core, contributing to chemical buoyancy — a potential energy source driving the geodynamo. The mechanism may also apply to the distribution of other light elements, influencing the core’s composition, dynamics, and evolution.
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