Enhancement of thermopower and thermoelectric performance through resonant distortion of electronic density of states of β-Zn4Sb3 doped with Sm

Abstract

Thermoelectric properties of Sm-doped compounds β-(Zn1−xSmx)4Sb3 (x = 0, 0.001, 0.002, and 0.003) (at 300-615 K) were investigated. The results indicate that Sm doping causes the resonant distortion of density of states of β-Zn4Sb3, as manifested by almost 2-fold increase in effective mass md* of β-Zn4Sb3, which results in ∼40 μV/K increase of the thermopower for all the doped samples. Besides, thermal conductivity decreases substantially by Sm doping. As a result, figure of merit ZT of β-(Zn0.008Sm0.002)4Sb3 is ∼53% larger than that of the un-doped one and reaches 1.1 at 615 K, suggesting that Sm doping is an effective approach to improve ZT of β-Zn4Sb3.