Threshold-controlled structural metamorphosis in black phosphorus under extreme conditions

This study integrates molecular dynamics simulations with shock compression experiments to elucidate the hierarchical phase transition mechanisms of black phosphorus under extreme pressure conditions. By establishing a phase transformation pathway model (orthorhombic → rhombohedral → simple cubic phase), we quantitatively determined the phase transition thresholds at 38.7 GPa under both ambient and elevated temperatures, and achieved controllable preparation of simple cubic phase black phosphorus through shock loading. The material porosity mediated pressure attenuation effect was found to critically influence the phase transition initiation pressure, while microsecond-scale pressure release characteristics enabled metastable phase retention by suppressing reverse transition kinetics. Atomic-scale analysis demonstrates that three-dimensional hydrostatic pressure drives anisotropic bonding reconstruction, characterized by 78.6 % preferential compression along the b-axis and continuous bond-angle distortion from 103° to 90°, which collectively induce electron cloud rearrangement and symmetry breaking transition from layered to cubic configurations. The developed simulation-experiment dual-validation methodology provides new perspectives for high-pressure phase transition research, with the revealed phase nucleation reverse transition competition mechanism offering critical guidance for metastable material design.