Pressure-induced phase transition of Bi2Te3 into the bcc structure

TL;DR

This study investigates the pressure-induced phase transition of Bi2Te3 to a bcc structure using synchrotron x-ray diffraction, revealing a high-pressure bcc phase and its structural model as a solid solution.

Contribution

First detailed characterization of Bi2Te3's high-pressure bcc phase and its structural modeling as a Bi-Te solid solution based on diffraction data.

Findings

High-pressure bcc phase appears above 14.5 GPa.

The bcc phase is recoverable upon decompression.

Structural model as a Bi-Te solid solution fits experimental data.

Abstract

The pressure-induced phase transition of bismuth telluride, Bi2Te3, has been studied by synchrotron x-ray diffraction measurements at room temperature using a diamond-anvil cell (DAC) with loading pressures up to 29.8 GPa. We found a high-pressure body-centered cubic (bcc) phase in Bi2Te3 at 25.2 GPa, which is denoted as phase IV, and this phase apperars above 14.5 GPa. Upon releasing the pressure from 29.8 GPa, the diffraction pattern changes with pressure hysteresis. The original rhombohedral phase is recovered at 2.43 GPa. The bcc structure can explain the phase IV peaks. We assumed that the structural model of phase IV is analogous to a substitutional binary alloy; the Bi and Te atoms are distributed in the bcc-lattice sites with space group Im-3m. The results of Rietveld analysis based on this model agree well with both the experimental data and calculated results. Therefore, the structure of phase IV in Bi2Te3 can be explained by a solid solution with a bcc lattice in the Bi-Te (60 atomic% tellurium) binary system.