Rapid Synthesis of Sb₂Si₂Te₆ under High Pressure with a Modulated Microstructure

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.