Lattice dynamics of Sb2Te3at high pressures

Abstract

We report an experimental and theoretical lattice dynamics study of antimony telluride (Sb 2 Te 3 ) up to 26 GPa together with a theoretical study of its structural stability under pressure. Raman-active modes of the low-pressure rhombohedral (R-3m) phase were observed up to 7.7 GPa. Changes of the frequencies and linewidths were observed around 3.5 GPa where an electronic topological transition was previously found. Raman mode changes evidence phase transitions at 7.7, 14.5, and 25 GPa. The frequencies and pressure coefficients of the new phases above 7.7 and 14.5 GPa agree with those calculated for the monoclinic C2/m and C2/c structures recently observed at high pressures in Bi 2 Te 3 , and also for the C2/m phase in the case of Bi 2 Se 3 and Sb 2 Te 3 . Above 25 GPa no Raman-active modes are observed in Sb 2 Te 3 similarly to the case of Bi 2 Te 3 and Bi 2 Se 3 . Therefore, it is possible that the structure of Sb 2 Te 3 above 25 GPa is the same disordered bcc phase already found in Bi 2 Te 3 by x-ray diffraction studies. Upon pressure release, Sb 2 Te 3 reverts back to the original rhombohedral phase after considerable hysteresis. Raman-and IR-mode symmetries, frequencies and pressure coefficients in the different phases are reported and discussed.

Structural, vibrational, and electrical study of compressed BiTeBr

“…This feature was interpreted as indicative of the occurrence of an ETT near 4 GPa, similar to that observed in several topological insulators (Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 ) [51][52][53]. Our measurements of the full width at half maximum of this Raman mode in BiTeBr (see Fig.…”

“…Finally, we must mention that in a previous work [15] it was reported that the E 2 (TO) mode, usually the most intense one in BiTeBr and BiTeI [52], showed a strong decrease in linewidth between room pressure and 4 GPa. This feature was interpreted as indicative of the occurrence of an ETT near 4 GPa, similar to that observed in several topological insulators (Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 ) [51][52][53].…”

High-Pressure Crystal Structure, Lattice Vibrations, and Band Structure of BiSbO4

“…The effect of including the SO coupling in the calculation of phonon frequencies at Γ is negligible (small differences of 1-3 cm -1 ). 35 …”

Pressure-induced electronic topological transition in Sb2S3

“…These compounds are extensively studied 3D topological insulators at ambient pressure. [16][17][18][19][20] Upon pressurizing them, they exhibit novel phenomena such as structural phase transitions, 21-23 electronic topological transitions (ETT) or Lifshitz transition, [21][22][23][24][25] insulator to metal transitions 26 and superconductivity [26][27] . The topological insulators Bi 2 Te 3 and Sb 2 Te 3 undergo series of pressure induced structural phase transitions from Rhombohedral (R m) to sevenfold monoclinic (S.G: C2/m, Z=4) followed by eightfold monoclinic (C2/c, Z=4) and finally to disordered body-centered cubic structure (space group Im-3m, Z=2), respectively.…”

“…[22][23][24][25][26] An ETT is an isostructural second order phase transition, no volume discontinuity and no change in Wyckoff positions are anticipated during this transition. 41 An ETT causes anomalous signature in mechanical, electrical and thermodynamic properties and it also affects vibrational properties.…”