The influence of doping sites on achieving higher thermoelectric performance for nanostructured α-MgAgSb

P-type nanostructured α-MgAgSb holds a great promise for low temperature waste heat energy harvesting. In this work, we first investigate the effect of doping site on the carrier transport behavior of nanostructured α-MgAgSb. Ca doping on Mg site is rationally chosen to optimize carrier concentration and thus enhance power factor. It is demonstrated that Ca doping on the Mg site leads to higher mobility and power factor in comparison with doping on Sb site, originated from the less introduced perturbation to valence band upon doping. As the result of doping-site effect, a peak ZT of ~1.3 at ~550 K and average ZT of ~1.1 between 300 K and 550 K are achieved by Ca doping on the Mg site. Our current work on only points out that doping on the site that has less influence on the charge-conducting band should be a critical doping principle in thermoelectric materials field, but also highlights the promising prospect of nanostructured α-MgAgSb for low temperature power generation.