Enhanced Weighted Mobility Induced High Thermoelectric Performance in Argyrodite Ag₈SnSe₆

The argyrodite family has emerged as a promising thermoelectric candidate due to its highly diffusive Ag ions and inherent low thermal conductivity. To address issues that commonly arise with hot pressing (HP) sintering, this study proposes to use the zone melting (ZM) method to synthesize high-density polycrystalline bulk Ag₈SnSe₆ samples. The thermoelectric properties of samples synthesized by the ZM and HP methods were thoroughly evaluated over a temperature range of 300 to 700 K. Due to the weaker scattering of electrons, the ZM-synthesized samples exhibited an ∼60% increase in weighted mobility, compared to those produced by the HP method. Despite the slight increase in thermal conductivity, the specimen synthesized by the ZM method achieves a higher peak zT value of 1.05 at 700 K. The average zT value also improves to 0.71 across the temperature range of 300 to 700 K. This work demonstrates the effectiveness of the ZM method in enhancing the thermoelectric performance of Ag₈SnSe₆, with great potential applicability to other argyrodite compounds.