Structural and vibrational study of Bi2Se3 under high pressure

Abstract

The structural and vibrational properties of bismuth selenide (Bi 2Se 3) have been studied by means of x-ray diffraction and Raman scattering measurements up to 20 and 30 GPa, respectively. The measurements have been complemented with ab initio total-energy and lattice dynamics calculations. Our experimental results evidence a phase transition from the low-pressure rhombohedral (R-3m) phase (¿-Bi 2Se 3) with sixfold coordination for Bi to a monoclinic C2/m structure (ß-Bi 2Se 3) with sevenfold coordination for Bi above 10 GPa. The equation of state and the pressure dependence of the lattice parameters and volume of ¿ and ß phases of Bi 2Se 3 are reported. Furthermore, the presence of a pressure-induced electronic topological phase transition in ¿-Bi 2Se 3 is discussed. Raman measurements evidence that Bi 2Se 3 undergoes two additional phase transitions around 20 and 28 GPa, likely toward a monoclinic C2/c and a disordered body-centered cubic structure with 8-fold and 9- or 10-fold coordination, respectively. These two high-pressure structures are the same as those recently found at high pressures in Bi 2Te 3 and Sb 2Te 3. On pressure release, Bi 2Se 3 reverts to the original rhombohedral phase after considerable hysteresis. Symmetries, frequencies, and pressure coefficients of the Raman and infrared modes in the different phases are reported and discussed. © 2011 American Physical Society.