Pressure-induced hydrogen bonding: structure of D2S phase I'

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Hydrogen sulfide exhibits complex phase behavior under varying pressure conditions.
• Understanding these phases is crucial for predicting material properties and chemical interactions.

Purpose of the Study:

• To elucidate the complete crystal structure of the high-pressure cubic phase I' of hydrogen sulfide.
• To investigate the molecular dynamics and bonding characteristics within this phase.

Main Methods:

• Neutron diffraction was employed to collect structural data.
• Analysis focused on molecular orientation and atomic distribution.

Main Results:

• The crystal structure of phase I' was fully determined.
• Molecules in phase I' exhibit partial rotational disorder around <111> axes.
• A greater nonuniformity in deuterium distribution was observed compared to phase II.
• Structural changes indicate the initiation of pressure-induced hydrogen bonding.

Conclusions:

• The high-pressure cubic phase I' of hydrogen sulfide has a distinct structure with significant molecular disorder.
• The transition to phase I' is marked by the onset of substantial pressure-induced hydrogen bonding.