Melting curve of superionic ammonia at planetary interior conditions

article Melting curve of superionic ammonia at planetary interior conditions published yes J.-A. Hernandez author Mandy Bethkenhagen author 201939f4-803f-11ed-ab7e-d8da4bd1517f0000-0002-1838-2129 S. Ninet author M. French author A. Benuzzi-Mounaix author F. Datchi author M. Guarguaglini author F. Lefevre author F. Occelli author R. Redmer author T. Vinci author A. Ravasio author BiCh department Under high pressures and temperatures, molecular systems with substantial polarization charges, such as ammonia and water, are predicted to form superionic phases and dense fluid states with dissociating molecules and high electrical conductivity. This behaviour potentially plays a role in explaining the origin of the multipolar magnetic fields of Uranus and Neptune, whose mantles are thought to result from a mixture of H2O, NH3 and CH4 ices. Determining the stability domain, melting curve and electrical conductivity of these superionic phases is therefore crucial for modelling planetary interiors and dynamos. Here we report the melting curve of superionic ammonia up to 300 GPa from laser-driven shock compression of pre-compressed samples and atomistic calculations. We show that ammonia melts at lower temperatures than water above 100 GPa and that fluid ammonia’s electrical conductivity exceeds that of water at conditions predicted by hot, super-adiabatic models for Uranus and Neptune, and enhances the conductivity in their fluid water-rich dynamo layers. Springer Nature2023 eng Nature Physics 1745-2473 1745-2481 00099692120000110.1038/s41567-023-02074-8 191280-1285 https://doi.org/10.1038/s41567-023-02130-3 Hernandez J-A, Bethkenhagen M, Ninet S, French M, Benuzzi-Mounaix A, Datchi F, Guarguaglini M, Lefevre F, Occelli F, Redmer R, Vinci T, Ravasio A. 2023. Melting curve of superionic ammonia at planetary interior conditions. Nature Physics. 19, 1280–1285. Hernandez, J.-A., Mandy Bethkenhagen, S. Ninet, M. French, A. Benuzzi-Mounaix, F. Datchi, M. Guarguaglini, et al. “Melting Curve of Superionic Ammonia at Planetary Interior Conditions.” Nature Physics. Springer Nature, 2023. <a href="https://doi.org/10.1038/s41567-023-02074-8">https://doi.org/10.1038/s41567-023-02074-8</a>. J.-A. Hernandez et al., “Melting curve of superionic ammonia at planetary interior conditions,” Nature Physics, vol. 19. Springer Nature, pp. 1280–1285, 2023. Hernandez J-A, Bethkenhagen M, Ninet S, et al. Melting curve of superionic ammonia at planetary interior conditions. Nature Physics. 2023;19:1280-1285. doi:<a href="https://doi.org/10.1038/s41567-023-02074-8">10.1038/s41567-023-02074-8</a> J.-A. Hernandez, M. Bethkenhagen, S. Ninet, M. French, A. Benuzzi-Mounaix, F. Datchi, M. Guarguaglini, F. Lefevre, F. Occelli, R. Redmer, T. Vinci, A. Ravasio, Nature Physics 19 (2023) 1280–1285. Hernandez, J.-A., Bethkenhagen, M., Ninet, S., French, M., Benuzzi-Mounaix, A., Datchi, F., … Ravasio, A. (2023). Melting curve of superionic ammonia at planetary interior conditions. Nature Physics. Springer Nature. <a href="https://doi.org/10.1038/s41567-023-02074-8">https://doi.org/10.1038/s41567-023-02074-8</a> Hernandez, J. A., et al. “Melting Curve of Superionic Ammonia at Planetary Interior Conditions.” Nature Physics, vol. 19, Springer Nature, 2023, pp. 1280–85, doi:<a href="https://doi.org/10.1038/s41567-023-02074-8">10.1038/s41567-023-02074-8</a>. 131182023-06-04T22:01:02Z2024-08-20T05:59:32Z