The critical role of boron doping in the thermoelectric and mechanical properties of nanostructured α-MgAgSb

The α-MgAgSb compound has attracted intensive attention as a promising candidate for the replacement of the traditional BiSbTe alloy for energy harvesting. Previous investigations have focused on how to enhance the thermoelectric performance while little interest has been placed on the aspect of mechanical properties. Herein, we highlighted the critical role of boron doping on the Sb site in the thermoelectric and mechanical properties of nanostructured α-MgAgSb, which significantly increased the mechanical properties without the deterioration of thermoelectric performance. The ineffectiveness of boron doping to enhance thermoelectric performance lied in the introduced perturbation to the valence band, resulting in a lower carrier mobility and power factor in comparison with that of doping on the Mg site. Due to the significant solution strengthening by boron doping, the corresponding Vickers microhardness values have been largely increased, which can be comparable to those of the mechanically robust p-type filled skutterudite. Our results not only highlight the promising prospect of α-MgAgSb-based materials for power generation but also provide a new and facile way to strengthen thermoelectric materials.