Rapid Synthesis of Sb2Si2Te6 under High Pressure with a Modulated Microstructure.

Abstract

Over the past decades, thermoelectric materials have advanced significantly, yet materials such as Sb2Si2Te6, which are challenging to synthesize chemically, often require lengthy and complex preparation processes, hindering their development. In this work, we prepare polycrystalline Sb2Si2Te6 bulk from elemental precursors using a high-pressure synthesis (HPS) method. This method offers significant advantages in efficiency and preparation duration. The applied pressure promotes an isotropic microstructure and regulates the thermoelectric properties by controlling precipitate contents, grain size, and twinning. Although an increase in thermal conductivity, mostly due to the notable increase in electrical conductivity, leads to less favorable thermal conductivity near room temperature compared to samples prepared using conventional methods, a beneficial reversal occurs at high temperatures. The polycrystalline Sb2Si2Te6 sample synthesized at 2 GPa demonstrates a peak ZT value of 1.1 at 773 K, outperforming most pristine Sb2Si2Te6 materials. This work demonstrates an efficient strategy for optimizing Sb2Si2Te6 performance and offers a new synthesis pathway for other challenging thermoelectric materials.