Lattice Dynamics Study of Elemental Bismuth under High Pressure

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We report a combined experimental and theoretical study of the lattice dynamics of different high-pressure phases of bismuth and their pressure dependence. The stability and the lattice dynamics of the different phases were calculated at room and high pressures. Raman-scattering experiments were performed up to 9 GPa, and the Raman spectrum of the Bi-III phase with a guest–host structure was measured for the first time. The assignment of the Raman modes of the Bi-II phase and the pressure dependence of the Bi-I, Bi-II, and Bi-III phases were obtained using density-functional theory (DFT) calculations. From the DFT calculations, we have determined the vibrational modes due to the motion of the guest atoms along the c direction.