Realizing Enhanced Thermoelectric Performance in Zintl-Phase SrCuSb by Reducing the Thermal Conductivity

Abstract

Zintl-phase compounds have been extensively studied in recent years due to their phonon-glass and electron-crystal structure. As a ZrBeSi-type Zintl-phase compound, SrCuSb exhibits both high electrical transport properties and thermal conductivity because of the fully occupied anionic framework. In this work, the thermoelectric properties of SrCuSb were refined by Sr self-doping. The increased Sr content not only suppressed the secondary phase SrCu2Sb2 but also lowered the carrier contribution to the thermal conductivity. A zT value of ∼0.36 was achieved for Sr1.05CuSb at 700 K. To further decrease the thermal conductivity, Ba was introduced to the alloy at the Sr site. Benefiting from the point defect scattering, the lattice thermal conductivity was reduced to ∼0.7 W K–1 m–1 at 760 K for the Sr0.75Ba0.3CuSb sample. Finally, a peak zT of ∼0.5 was obtained for Sr0.75Ba0.3CuSb at 773 K.