Accelerated Exploration of Empty Material Compositional Space: Mg-Fe-B Ternary Metal Borides

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Discovery

Background:

• Borides possess diverse structures and properties, offering potential for new material discovery through elemental substitution.
• Exploring uncharted compositional spaces, like the Mg-Fe-B system, presents significant prediction and synthesis challenges.

Purpose of the Study:

• To develop and apply a workflow combining high-throughput crystal structure prediction and automated diffraction pattern matching.
• To explore the ternary Mg-Fe-B compositional space and discover novel boride compounds.

Main Methods:

• Utilized a workflow integrating crystal structure prediction and powder X-ray diffraction (PXRD) pattern matching.
• Classified 275 ternary boride prototypes and predicted stable/metastable phases in the Mg-Fe-B system.
• Analyzed structural properties of newly discovered compounds, including Mg2Fe7B7 and MgFe3B2.

Main Results:

• Predicted 23 stable and 158 metastable ternary phases within 50 and 200 meV/atom above the convex hull, respectively.
• Identified Mg2Fe7B7 and MgFe3B2, matching previously unsolved experimental PXRD patterns.
• Discovered channeled structures in Mg2Fe7B7 with potential for fast Mg superionic transport and excellent electrochemical performance.

Conclusions:

• The discovered borides, particularly Mg2Fe7B7, are promising candidates for post-Li-ion battery electrode materials and fast ionic conductors.
• The developed workflow efficiently explores material compositional spaces, paving the way for discovering novel ternary metal borides.
• This study expands the understanding of ternary metal borides and their potential applications.