Stability and Phase Transition of Metastable Black Arsenic under High Pressure.

Black arsenic (bAs) is a metastable phase of arsenic that has attracted increasing interest owing to its layered structure, tunable band gap, high carrier mobility, and large on/off ratio. Here, we systematically investigated the high-pressure behaviors of bAs up to ∼14 GPa. A phase transition from bAs to gray arsenic (gAs) occurred at critical pressure of 3.48 GPa, and the bAs and gAs coexisted between 3.48 and 5.37 GPa before bAs completely converted to gAs above 5.37 GPa. The structure was reversible for bAs after pressure was released from about 1-3 GPa, indicating the stability of bAs at pressures less than the critical pressure. At pressures above 5.37 GPa, bAs transformed to gAs and remained gAs after pressure was released. Molecular dynamics (MD) simulation was performed to explain the phase transition mechanism. This work provides insights into the phase stability and phase transition of metastable bAs under high pressure.