On a new nitrogen sX hydrate from ice XVII

Area of Science:

• Materials Science
• Chemistry
• Crystallography

Background:

• A novel gas hydrate structure, designated sX, has been identified.
• Structure sX is unique as the only known gas hydrate possessing chiral channels.
• It forms from hydrogen-water or carbon dioxide-water mixtures above 0.300 GPa.

Purpose of the Study:

• To investigate the refillability of the sX gas hydrate structure with nitrogen.
• To analyze the decomposition behavior of the sX structure under specific conditions.
• To determine the guest:host ratio for nitrogen within the sX structure.

Main Methods:

• Neutron diffraction data analysis.
• Density-functional theory calculations.
• Investigation of hydrate decomposition pathways.

Main Results:

• The sX gas hydrate structure is refillable with nitrogen, with a guest:host ratio of 2.6(3).
• Decomposition studies revealed transitions into exotic hydrates sH and sIII.
• These transitions occurred before the formation of the stable nitrogen hydrate sII.

Conclusions:

• The sX structure demonstrates potential as a storage material for gases beyond hydrogen, including nitrogen.
• Understanding its decomposition pathways provides insights into hydrate phase transitions.
• The unique chiral nature of sX contributes to its distinct gas storage and phase behavior.