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High-Pressure Neutron Diffraction Study on ε-FeOOH: The Spin-Reorientation Transition and Hydrogen-Bond
Osamu Ikeda1, Hajime Yamamoto2, Asami Sano-Furukawa3
1Department of Earth Science, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Journal of the American Chemical Society
|January 24, 2025
Summary
High pressure induces magnetic and structural changes in iron oxyhydroxide (ε-FeOOH). A spin reorientation occurs at 8 GPa, and crystal symmetry changes above 17 GPa, impacting hydrogen bonds and magnetic anisotropy.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Iron oxyhydroxide (ε-FeOOH) exhibits complex compression behavior.
- Understanding pressure-induced changes in magnetic properties and bonding is crucial.
Purpose of the Study:
- Investigate the spin-reorientation transition and hydrogen-bond symmetrization in ε-FeOOH and ε-FeOOD under high pressure.
- Determine the correlation between magnetic transitions and hydrogen-bond behavior.
Main Methods:
- In situ powder neutron diffraction experiments.
- Compression of ε-FeOOH and ε-FeOOD up to pressures exceeding 20 GPa.
Main Results:
- A magnetic spin-flop transition was observed at 8 GPa in both ε-FeOOH and ε-FeOOD.
- Fe-spins reoriented from the c-direction to the b-direction above 8 GPa.
- Crystal symmetry transitioned from P21nm to Pnnm at 17.90 GPa in ε-FeOOH, with H-bond symmetrization, while ε-FeOOD remained asymmetric.
Conclusions:
- Pressure significantly affects the magnetic and structural properties of ε-FeOOH.
- The observed spin reorientation and H-bond symmetrization are interconnected.
- This study offers insights into pressure effects on magnetic transitions in hydrogen-bonded compounds.
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