Structural evolution and superionic state of MnOOH under high-pressure and high-temperature
Yuelong Ding1, Haoyu Wang1, Wenwen Cui1
1Jiangsu Key Laboratory of Extreme Multi-Field Materials Physics, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
The Journal of Chemical Physics
|October 22, 2025
Summary
Scientists discovered a new hydrous mineral, Pbca-MnOOH, stable deep within Earth. This manganese oxyhydroxide may transport water in the mantle, offering insights into deep-Earth processes.
Area of Science:
- Geochemistry
- Mineral Physics
- Computational Materials Science
Background:
- Hydrous minerals are crucial for understanding deep Earth water storage.
- Previous studies have explored various water-bearing phases under extreme conditions.
Purpose of the Study:
- To identify and characterize novel hydrous mineral phases stable at deep Earth pressures.
- To investigate the structural, electronic, and transport properties of these phases.
Main Methods:
- Crystal structure prediction algorithms.
- First-principles calculations (density functional theory).
- Ab initio molecular dynamics simulations.
Main Results:
- A new Pbca-MnOOH phase was identified, stable between 34-75 GPa.
- The structure features a 3D framework of MnO6 octahedra with mixed covalent and ionic bonding.
- Simulations show this phase becomes superionic under high-pressure, high-temperature conditions.
Conclusions:
- The Pbca-MnOOH phase is a potential candidate for deep-Earth water transport.
- This discovery enhances our understanding of manganese oxyhydroxide behavior under mantle conditions.
- Provides critical data on pressure-induced structural and transport properties of hydrous minerals.
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