High-pressure phase transitions, amorphization, and crystallization behaviors in Bi₂Se₃

The phase transition, amorphization, and crystallization behaviors of the topological insulator bismuth selenide (Bi₂Se₃) were discovered by performing in situ high-pressure angle-dispersive x-ray diffraction experiments during an increasing, decreasing, and recycling pressure process. In the compression process, Bi₂Se₃ transforms from the original rhombohedral structure (phase I(A)) to a monoclinic structure (phase II) at about 10.4 GPa, and further to a body-centered tetragonal structure (phase III) at about 24.5 GPa. When releasing pressure to ambient conditions after the complete transformation from phase II to III, Bi ₂Se₃ becomes an amorphous solid (AM). In the relaxation process from this amorphous state, Bi₂Se₃ starts crystallizing into an orthorhombic structure (phase I(B)) about five hours after releasing the pressure to ambient. A review of the pressure-induced phase transition behaviors of A_2B3-type materials composed from the V and VI group elements is presented.