Structural transitions of BiI _3 under pressure

摘要

High pressure studies of BiI _3 at 0 K are performed using first-principles pseudopotential calculations within the framework of density functional theory. The calculations indicate that BiI _3 undergoes a structural transition from rhombohedral R-3 phase to monoclinic P2 _(1/c) phase at 7 GPa which is accompanied by a 5.8% volume collapse. In addition, we find that P2 _(1/c) phase prevails about 60 GPa range and transforms to cubic Fm-3m phase at 68 GPa, and finally takes the orthorhombic Pnma phase at high pressures up to 133 GPa. The structural and electronic properties of four competitive structures are also calculated. The analysis of density of states reveals that BiI _3 has semiconductor-metal transition at about 61 GPa, which also demonstrates the metallic nature of both Fm-3m and Pnma phases.