Quenchable Amorphous Diamond: A Novel High-Pressure Route to Tetrahedral Amorphous Carbon

Abstract

This study presents a groundbreaking theoretical prediction: the high-pressure transformation of amorphous graphite into a high-fraction sp³-bonded amorphous diamond phase. Employing ab initio molecular dynamics simulations, it is demonstrated that under extreme pressures, amorphous graphite undergoes an irreversible transition to an amorphous diamond phase. Thermodynamic analysis confirms the first-order nature of this sp²-to-sp³ transformation, with the transition predicted to occur at ≈33 GPa under experimental conditions. This transformation offers a novel pathway toward the synthesis of amorphous carbon with a high fraction of sp³ bonding, a long-standing challenge in materials science. This work expands understanding of carbon's high-pressure behavior and provides a compelling theoretical foundation for future experimental investigations aimed at synthesizing and characterizing this novel material.