Unlocking the thermoelectric potential of the Ca 14 AlSb 11 structure type.

Yb 14 MnSb 11 and Yb 14 MgSb 11 are among the best p-type high-temperature (>1200 K) thermoelectric materials, yet other compounds of this Ca 14 AlSb 11 structure type have not matched their stability and efficiency. First-principles computations show that the features in the electronic structures that have been identified to lead to high thermoelectric performances are present in Yb 14 ZnSb 11 , which has been presumed to be a poor thermoelectric material. We show that the previously reported low power factor of Yb 14 ZnSb 11 is not intrinsic and is due to the presence of a Yb 9 Zn 4+ x Sb 9 impurity uniquely present in the Zn system. Phase-pure Yb 14 ZnSb 11 synthesized through a route avoiding the impurity formation reveals its exceptional high-temperature thermoelectric properties, reaching a peak zT of 1.2 at 1175 K. Beyond Yb 14 ZnSb 11 , the favorable band structure features for thermoelectric performance are universal among the Ca 14 AlSb 11 structure type, opening the possibility for high-performance thermoelectric materials.