New pressure-induced monoclinic {\beta}-Sb2Te3 phase with sevenfold symmetry

TL;DR

This study reports the synthesis of nanometric Sb2Te3 and its pressure-induced phase transition from rhombohedral to a monoclinic {eta}-phase with sevenfold symmetry, characterized by XRD and Raman spectroscopy.

Contribution

It provides the first detailed analysis of the structural stability and phase transformation of nanometric Sb2Te3 under pressure using synchrotron XRD and Raman spectroscopy.

Findings

Phase transition occurs between 9.8 and 13.2 GPa.

The monoclinic {eta}-Sb2Te3 phase has sevenfold symmetry.

Bulk modulus of nano-Sb2Te3 is slightly lower than bulk Sb2Te3.

Abstract

A nanometric Sb2Te3 rhombohedral phase was produced from Sb and Te by mechanical alloying for 3 hours and its structural stability was studied by synchrotron X-ray diffraction (XRD) and Raman spectroscopy (RS) measurements as a function of pressure. A phase transformation from the ambient pressure rhombohedral phase into a {\beta}-Sb2Te3 monoclinic structure between 9.8 and 13.2 GPa is observed by XRD. This phase transformation is confirmed by the Raman spectroscopy measurements. The pressure dependence of the volume fited to a Birch-Murnaghan equation of state gives a bulk modulus B0 = 40.6 +- 1.5 GPa and B'0 = 5.1 +- 0.6. The bulk modulus of the nano-Sb2Te3 seems to be slightly smaller than that for its bulk counterpart (44.8 GPa).