Partially Diffusive Helium-Silica Compound in the Deep Interiors of Giant Planets

Abstract

Helium is the second most abundant element in the universe, and together with silica, they are major components of giant planets. Exploring the reactivity and state of helium and silica under high pressure is of fundamental importance for developing and understanding of the evolution and internal structure of giant planets. Here, using first-principles calculations and crystal structure predictions, we identify four stable phases of a helium-silica compound with seven/eight-coordinated silicon atoms at pressure range of 600-4000 GPa, corresponding to the interior condition of the outer planets in the solar system. The density of HeSiO2 agrees with current structure models of the planets. This helium-silica compound exhibits a superionic-like helium diffusive state at the high pressure and high temperature conditions along the isentropes of Saturn, a metallic fluid state in Jupiter, and a solid state in the deep interiors of Uranus and Neptune. The reaction of helium and silica may lead to the erosion of the rocky core of giant planets and form a diluted core region. These results highlight the reactivity of helium under high pressure to form new compounds, and also provides evidence to help build more sophisticated interior models of giant planets.

20 pages, 5 figures

References in corpus (18)

• Ab initio Random Structure Searching
• High-pressure phases of silane
• A stable compound of helium and sodium at high pressure
• Shock Compression of Deuterium and the Interiors of Jupiter and Saturn
• New indication for a dichotomy in the interior structure of Uranus and Neptune from the application of modified shape and rotation data
• New models of Jupiter in the context of Juno and Galileo
• A novel superhard tungsten nitride predicted by machine-learning accelerated crystal structure searching
• Uranus and Neptune: Origin, Evolution and Internal Structure
• The Formation of Jupiter's Diluted Core by a Giant Impact
• Jupiter internal structure: the effect of different equations of state
• The Challenge of Forming a Fuzzy Core in Jupiter
• Interior Models of Saturn: Including the Uncertainties in Shape and Rotation
• Planetary Ices and the Linear Mixing Approximation
• Superionic silica-water and silica-hydrogen compounds under high pressure
• cij: A Python code for quasiharmonic thermoelasticity
• Ultrahigh-Pressure Magnesium Hydrosilicates as Reservoirs of Water in Early Earth
• Dimensionalities and multiplicities determination of crystal nets
• The Interiors of Jupiter and Saturn