EGU21-817
https://doi.org/10.5194/egusphere-egu21-817
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Solid to superionic transition in iron oxide-hydroxide

Qingyang Hu1, Mingqiang Hou1,2, and Yu He1,3
Qingyang Hu et al.
  • 1Center for High Pressure Science and Technology Advanced Research, Beijing Headquarter, Beijing, China (qingyang.hu@hpstar.ac.cn)
  • 2Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, USA
  • 3Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China

At planetary interior conditions, water ice has been proved to enter a superionic phase recently since it was predicted about 30-year ago. Hydrogen in superionic water become liquid-like, and move freely within solid oxygen lattice. Under extreme pressure and temperature conditions of Earth’s deep mantle, the solid-superionic transition can also occur readily in the pyrite-type FeO2Hx, a candidate mineral in the lower mantle and probably also in other hydrous minerals. We find that when the pressure increases beyond 73 GPa at room temperature, symmetric hydroxyl bonds are softened and the H+ (or proton) become diffusive within the vicinity of its crystallographic site. Increasing temperature under pressure, the diffusivity of hydrogen is extended beyond individual unit cell to cover the entire solid, and the electrical conductivity soars, indicating a transition to the superionic state which is characterized by freely-moving proton and solid FeO2 lattice. The superionic hydrogen will dramatically change the geophysical picture of electrical conductivity and magnetism, as well as geochemical processes of hydrogen isotopic mixing and redox equilibria at local regions of Earth’s deep interiors.

How to cite: Hu, Q., Hou, M., and He, Y.: Solid to superionic transition in iron oxide-hydroxide, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-817, https://doi.org/10.5194/egusphere-egu21-817, 2021.