Computationally Directed Discovery of MoBi₂.

Area of Science:

• Materials Science
• Solid State Chemistry
• High-Pressure Physics

Background:

• Bismuth (Bi), the heaviest stable element, imparts unique properties like magnetism and superconductivity when incorporated into materials.
• Understanding bismuth's reactivity is key to developing novel materials with emergent properties.
• High pressure serves as a powerful tool to induce reactions between elements not reactive under ambient conditions.

Purpose of the Study:

• To explore the Mo-Bi system under high pressure, seeking novel binary intermetallic structures.
• To investigate the role of pressure in driving reactivity and forming new Mo-Bi compounds.
• To demonstrate the synergy of computational and experimental approaches in high-pressure materials discovery.

Main Methods:

• Computational materials discovery using the ab initio random structure searching (AIRSS) method to identify potential Mo-Bi structures.
• High-pressure in situ powder X-ray diffraction (XRD) experiments using diamond anvil cells (DACs).
• Electronic structure and phonon dispersion calculations to analyze material properties.

Main Results:

• Identification of multiple synthetic targets in the Mo-Bi system within the 0-50 GPa pressure range.
• Experimental confirmation of the predicted CuAl₂-type MoBi₂ structure at 35.8(5) GPa.
• Discovery of a correlation between valence electron count and bonding in high-pressure transition metal-Bi structures.
• Identification of two dynamically stable ambient pressure polymorphs for MoBi₂.

Conclusions:

• The Mo-Bi system exhibits rich high-pressure chemistry, leading to the formation of previously unknown intermetallic compounds.
• The combined computational-experimental approach is highly effective for discovering new materials under extreme conditions.
• This study provides insights into the factors governing structure formation in high-pressure transition metal-bismuth systems.