Raman study of black phosphorus up to 13 GPa

Raman scattering experiments of a single crystal of black phosphorus have been carried out at room temperature in a wide pressure range from 0.55 to 13 GPa in order to study a band overlapped metallization at 1.5 GPa and the structural phase transitions. Five Raman-active modes in the orthorhombic (A11) phase were detected as a function of pressure. The softening of the B-1g and B-3g(1) modes was observed around 2 GPa. Above 4.7 GPa, these modes showed a sudden decrease in the intensity and two new broad bands appeared at 388 and 308 cm(-1), corresponding to a transition to the rhombohedral (A7) phase. The broad bands which were assigned to the A(1g) and E-g modes of the A7 phase, exhibited remarkable softening with pressure. The A7 phase coexisted with the A11 phase up to 7 GPa. The transition to the simple cubic phase was also observed at 10.5 GPa with vanishment of the A(1g)mode. (C) 1997 Published by Elsevier Science Ltd.