Structural Changes in Thermoelectric SnSe at High Pressures

TL;DR

This study investigates how the crystal structure of thermoelectric SnSe changes under high pressure, revealing a phase transition that could inform the development of more stable thermoelectric materials.

Contribution

It provides the first detailed analysis of SnSe's structural evolution under high pressure, identifying a phase transition at 10.5 GPa and linking it to high-temperature phases.

Findings

SnSe undergoes a continuous structural transition at 10.5 GPa

High-pressure phase resembles high-temperature phase

Structural insights suggest potential for strained thin films

Abstract

The crystal structure of the thermoelectric material tin selenide has been investigated with angle-dispersive synchrotron x-ray powder diffraction under hydrostatic pressure up to 27 GPa. With increasing pressure, a continuous evolution of the crystal structure from the GeS type to the higher-symmetry TlI type was observed, with a critical pressure of 10.5(3) GPa. The orthorhombic high-pressure modification, beta'-SnSe, is closely related to the pseudo-tetragonal high-temperature modification at ambient pressure. The similarity between the changes of the crystal structure at elevated temperatures and at high pressures suggests the possibility that strained thin films of SnSe may provide a route to overcoming the problem of the limited thermal stability of beta-SnSe at high temperatures.