Spinel-type Al4C3 attainable above 7 GPa and more high-pressure phases of Al4C3
Mitchell Falgoust1, Peter Kroll1
1Department of Chemistry and Biochemistry, The University of Texas at Arlington 700 Planetarium Place Arlington Texas 76019 USA pkroll@uta.edu.
Chemical Science
|December 15, 2025
Summary
Aluminum carbide (Al4C3) is predicted to form a stable anti-spinel structure (Al4C3-II) under high pressure. This phase exhibits excellent mechanical properties, including high bulk modulus and Vickers hardness, suggesting potential applications.
Area of Science:
- Materials Science
- High-Pressure Physics
- Computational Chemistry
Background:
- Aluminum carbide (Al4C3) is a compound with potential industrial applications.
- Understanding its phase diagram under pressure is crucial for exploring new material properties.
Purpose of the Study:
- To predict the high-pressure structural phases of aluminum carbide (Al4C3).
- To investigate the mechanical properties of predicted Al4C3 phases.
- To guide experimental research in the Al-C system.
Main Methods:
- Density Functional Theory (DFT) calculations.
- Predictive modeling of crystal structures under varying pressures.
- Analysis of thermodynamic stability and mechanical properties.
Main Results:
- Al4C3 is predicted to adopt a cubic, anti-spinel-type structure (Al4C3-II) between 7 and 33 GPa, with peak stability at 26 GPa.
- Al4C3-II exhibits a bulk modulus of 160 GPa and a Vickers hardness of approximately 30 GPa at ambient pressure.
- Three additional post-spinel phases, including an anti-Th3P4-type structure at 140 GPa, were identified.
Conclusions:
- The trigonal ground state of Al4C3 is expected to undergo multiple phase transitions under pressure.
- The predicted Al4C3-II phase is mechanically robust and accessible experimentally.
- Experimental investigation of the Al-C system at high pressures is encouraged.
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