Double-icosahedral Li clusters in a new binary compound Ba(19)Li(44): a reinvestigation of the Ba-Li phase diagram

Area of Science:

• Materials Science
• Inorganic Chemistry
• Solid-State Chemistry

Background:

• The barium-lithium (Ba-Li) binary system is crucial for understanding intermetallic compound formation.
• Previous studies have explored various compositions within the Ba-Li system.
• Further investigation is needed for compositions rich in lithium.

Purpose of the Study:

• To reinvestigate the Ba-Li system for compositions containing less than 80 at. % Li.
• To identify and structurally characterize new compounds within this composition range.
• To understand the structural features of lithium-rich barium compounds.

Main Methods:

• Reinvestigation of the Ba-Li system using compositional analysis.
• Single-crystal X-ray diffraction for structural determination.
• Characterization of phase stability and crystallographic parameters.

Main Results:

• A new compound, barium tetratetracontadidecide (Ba(19)Li(44)), was identified.
• Ba(19)Li(44) is stable up to 126°C.
• The compound crystallizes in a novel tetragonal structure (space group I42d) with complex polytetrahedral clusters, related to the chalcopyrite structure.

Conclusions:

• The discovery of Ba(19)Li(44) expands the known phase diagram of the Ba-Li system.
• The structural complexity, featuring icosahedron-based clusters, is characteristic of lithium-rich intermetallic phases.
• This finding contributes to the understanding of structure-property relationships in complex metal-rich compounds.