Cost effective synthesis of p-type Zn-doped MgAgSb by planetary ball-milling with enhanced thermoelectric properties

Abstract

As promising candidates for the progress of low-temperature thermoelectric devices, MgAgSb-based thermoelectric materials have drawn a great deal of attention. However, due to complicated phase changes, high content of impurities and high volatilization of Mg, it is difficult to synthesize pure phase MgAgSb-based thermoelectric materials via conventional methods. Here, MgAgSb alloy was successfully synthesized by a combination of common planetary ball milling and spark plasma sintering. Furthermore, the introduction of Zn improved the purity of alloys, leading to optimization of the electrical transport properties. As a result, the power factor was improved from 1087 μW m⁻¹ K⁻² for MgAg_0.9Sb_0.95 to 1394 μW m⁻¹ K⁻² for Mg_0.97Zn_0.03Ag_0.9Sb_0.95 at 473 K, and the ZT reached ∼0.7 at 473 K. These results suggest that MgAgSb-based thermoelectric materials have a good thermoelectric application potential and this study can be used as guidance for the synthesis and performance improvement of other thermoelectric materials. Our synthesis route sets forth a new avenue for accelerating commercial applications of MgAgSb-based thermoelectric power generation or refrigeration.