Sm_26.25Ge_22.75O₅: Oxidic Sm₃₀Ge₄O₅ Superclusters Embedded in a Zintl Polyanionic Framework

Area of Science:

• Solid State Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• Rare-earth germanides and oxides are classes of materials with diverse properties.
• Understanding the role of oxygen in stabilizing complex structures is crucial for materials design.

Purpose of the Study:

• To synthesize and characterize a novel heteroanionic rare-earth germanide oxide.
• To investigate the structural role and electronic effects of oxygen incorporation.

Main Methods:

• Arc melting for synthesis.
• Single-crystal X-ray diffraction for crystal structure determination.
• Density Functional Theory (DFT) calculations for chemical bonding and electronic structure analysis.

Main Results:

• A new compound, Sm26.25Ge22.75O5, was successfully synthesized and its crystal structure elucidated.
• The structure features [Sm6O] octahedra and [Sm8Ge] prisms forming superclusters with polyanionic Ge chains.
• Chemical bonding analysis and DFT calculations confirmed oxygen's critical role in stabilizing the structure and lowering the formation enthalpy.
• Both the suboxide and a hypothetical oxygen-free intermetallic compound exhibit metallic conductivity.

Conclusions:

• The heteroanionic rare-earth germanide oxide Sm26.25Ge22.75O5 represents a new structural type.
• Oxygen plays a vital role in stabilizing this complex germanide oxide structure.
• The compound exhibits metallic conductivity, suggesting potential applications in electronic materials.