Determinations of the high-pressure crystal structures of Sb₂Te₃

Abstract

Using the angle-dispersive synchrotron x-ray powder diffraction technique in a diamond anvil cell, the high-pressure behaviors of antimony telluride (Sb(2)Te(3)) are explored up to 52.7 GPa at room temperature. Three high-pressure phases have been observed, at about 8.0 GPa, 13.2 GPa and above 21.6 GPa, respectively. Furthermore, the crystalline structures of these high-pressure phases are determined as monoclinic sevenfold C2/m phase, eightfold C2/c phase and disordered body-centered cubic structure (space group Im - 3m) respectively. The phase-transition sequences and pressures observed are well explained by first-principles calculations. The pressure dependence of the volume of all high-pressure phases is described by a third-order Birch-Murnaghan equation of state. All the high-pressure phases are metallic and the metallic character for β-, γ- and δ-Sb(2)Te(3) increases in turn based on the results of the electronic density of states calculated for each high-pressure phase.

Sb2Se3 under pressure

“…Within the Im -3 m phase, the Sb and Se atoms are randomly distributed on the bcc lattice sites, forming a Sb-Se substitutional alloy. A similar phase transition has been observed for the Bi 2 Te 3 67 and Sb 2 Te 3 1920 compounds above ~15 GPa and ~22 GPa, respectively.…”

“…Regarding the former, recent high-pressure studies of the Bi 2 Te 3 678910111213, Bi 2 Se 3 1415161718, and Sb 2 Te 3 91920212223 compounds have revealed several interesting effects. In particular, a pressure-induced electronic topological transition has been observed for all of these materials in the R -3 m phase10111822.…”

“…As an example, their thermoelectric properties are enhanced by application of external pressure1, a feature attributed to an electronic topological transition. More recent and detailed high-pressure investigations on Bi 2 Te 3 678910111213, Bi 2 Se 3 1415161718, and Sb 2 Te 3 91920212223 have revealed a plethora of phase transitions. In particular, novel structures with higher cationic coordinations67141518192021, insulator-to-metal transitions916, and even superconductivity8121323 have been observed upon increasing pressure.…”

“…The key findings of this work can be summarized as follows:

A novel binary alloy between Sb and Se atoms was observed. In particular, the ambient-pressure Pnma phase of Sb 2 Se 3 persists up to ~51 GPa; beyond that pressure, Sb 2 Se 3 begins to transform into a disordered cubic bcc phase (SG Im -3 m , Z = 2), similar to the Bi 2 Te 3 67 and Sb 2 Te 3 1920 compounds. The transition, which is reversible, is not fully completed up to the highest pressure reached here, i.e.

…”

High-Pressure Studies of Bi2S3

“…5,12,44 In particular, the heaviest member of this series, i.e., Bi 2 Te 3 undergoes three structural transitions up to 52 GPa. 5,10,11 In particular, the starting R3̅ m phase transforms into a monoclinic structure (C2/m, Z = 4) with 7-fold cationic coordination above 8 GPa.…”