2024/10/23 by Kyla de Villa, de Villa, Kyla, Felipe González‐Cataldo +3 · 2 citations
Chemistry · Environmental Science · Physics and Astronomy · #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Inorganic Fluorides and Related Compounds #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Materials Science (cond-mat.mtrl-sci) #Methane Hydrates and Related Phenomena #Quantum, superfluid, helium dynamics
paper · pdf · doi:10.48550/arxiv.2410.17499
openalex publication_date 2024/10/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The ice giant planets Uranus and Neptune are assumed to contain large amounts of planetary ices such as water, methane, and ammonia. The properties of mixtures of such ices at the extreme pressures and temperatures of planetary interiors are not yet well understood. Ab initio computer simulations predicted that a number of ices exhibit a hydrogen superionic state and a doubly superionic state [DOI: 10.1038/s41467-023-42958-0]. Since the latter state has not yet been generated with experiments, we outline here two possible pathways for reaching and detecting such a state with dynamic compression experiments. We suggest X-ray diffraction as the principal tool for detecting when the material becomes doubly superionic and the sublattice of one of the heavy nuclei melts. That would require a temperature of ∼3500 K and pressures greater than ∼200 GPa for H3NO4, which we use as an example material here. Such conditions can be reached with experiments that employ an initial shock that is followed by a ramp compression wave. Alternatively, one may use triple-shock compression because a single shock does not yield sufficiently high densities.