New models shed light on how an exotic phase of hydrogen in Earth's core may behave
While Earth's core consists mostly of iron, its density implies that lighter elements are also mixed in. Because hydrogen is abundant in the universe and can mix with iron under certain conditions, scientists suspect it makes up part of the lighter-element composition. Data from earthquakes suggest the inner part of the core also changes with depth, but scientists aren't sure exactly how this…
A new study published in the Proceedings of the National Academy of Sciences sheds light on the behavior of an exotic phase of hydrogen within Earth's core. While the core is primarily composed of iron, scientists suspect that hydrogen, a common element in the universe, may be mixed with it under certain conditions. Data from earthquakes suggests that the inner part of the core changes with depth, but the exact mechanism remains unclear.
The new research indicates that hydrogen likely exists in a gradient within the inner and outer core, resulting from thermodynamic equilibrium. Hydrogen can dissolve into iron under extreme conditions, such as the high-temperature, high-pressure environment found in Earth's core. In the inner core, hydrogen may transform into a superionic state, allowing it to move through a solid iron crystal structure almost like a liquid.
This superionic state does not behave like a conventional solid and can influence the thermodynamic properties of various phases. The study authors employed quantum-mechanical simulations to calculate the free energies of iron-hydrogen mixtures and model solid, superionic, and liquid states at pressures and temperatures found in the inner core.
Their models suggest that hydrogen is more concentrated near the boundary between Earth's inner and outer core and decreases as it approaches the planet's center.
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