Pressure-stabilized lithium caesides with caesium anions beyond the -1 state

Area of Science:

• High-pressure physics and chemistry
• Materials science
• Solid-state chemistry

Background:

• Main group elements typically exhibit fixed oxidation states in compounds.
• Group I alkali metals commonly form +1 cations.
• Recent findings suggest pressure can induce unusual reactivity in cesium's 5p electrons.

Purpose of the Study:

• To investigate the formation of novel alkali metal compounds under extreme pressure.
• To explore the possibility of anionic cesium species.
• To predict the structural and electronic properties of predicted Li-Cs intermetallics.

Main Methods:

• High-throughput computational screening.
• Density functional theory (DFT) calculations.
• Phase diagram prediction under pressure.

Main Results:

• Stable intermetallic compounds Li extsubscript{n}Cs (n=1-5) predicted to form above 100 GPa.
• Discovery of unique structural motifs like capped cuboids and dimerized icosahedra.
• Cesium adopts a significantly anionic state (formal charge < -1) in these compounds.

Conclusions:

• Pressure enables the formation of unprecedented anionic cesium compounds with light alkali metals.
• These Li-Cs intermetallics display novel structural characteristics.
• The anionic state of cesium influences potential superconductivity in metastable LiCs phases.