Synthesis of FeH₅: A layered structure with atomic hydrogen slabs

Area of Science:

• Materials Science
• High-Pressure Physics
• Solid-State Chemistry

Background:

• High pressure drives the formation of polyhydrides with high hydrogen content.
• These materials feature intricate hydrogenic sublattices.

Purpose of the Study:

• To synthesize and characterize iron pentahydride (FeH5).
• To investigate the structural and electronic properties of FeH5 under high pressure.

Main Methods:

• Direct reaction between iron and H2 gas.
• Utilized a laser-heated diamond anvil cell at pressures exceeding 130 gigapascals.

Main Results:

• Successfully synthesized iron pentahydride (FeH5).
• FeH5 exhibits a novel structure composed solely of atomic hydrogen, with intercalated quasicubic FeH3 units and atomic hydrogen layers.
• Valence electron density distribution indicates Fe-H bonding, metallic character, and no H-H bonding.

Conclusions:

• The discovery of FeH5 provides insights into hydrogen-metal interactions under extreme conditions.
• Suggests a potential low-pressure route for synthesizing materials resembling bulk dense atomic hydrogen.